1	/* Target hook definitions.
2	Copyright (C) 2001-2025 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 last parameter
1922	is true if the access is defined in a packed struct. */
1923	DEFHOOK
1924	(support_vector_misalignment,
1925	"This hook should return true if the target supports misaligned vector\n\
1926	store/load of a specific factor denoted in the @var{misalignment}\n\
1927	parameter. The vector store/load should be of machine mode @var{mode} and\n\
1928	the elements in the vectors should be of type @var{type}. @var{is_packed}\n\
1929	parameter is true if the memory access is defined in a packed struct.",
1930	bool,
1931	(machine_mode mode, const_tree type, int misalignment, bool is_packed),
1932	default_builtin_support_vector_misalignment)
1933
1934	/* Returns the preferred mode for SIMD operations for the specified
1935	scalar mode. */
1936	DEFHOOK
1937	(preferred_simd_mode,
1938	"This hook should return the preferred mode for vectorizing scalar\n\
1939	mode @var{mode}. The default is\n\
1940	equal to @code{word_mode}, because the vectorizer can do some\n\
1941	transformations even in absence of specialized @acronym{SIMD} hardware.",
1942	machine_mode,
1943	(scalar_mode mode),
1944	default_preferred_simd_mode)
1945
1946	/* Returns the preferred mode for splitting SIMD reductions to. */
1947	DEFHOOK
1948	(split_reduction,
1949	"This hook should return the preferred mode to split the final reduction\n\
1950	step on @var{mode} to. The reduction is then carried out reducing upper\n\
1951	against lower halves of vectors recursively until the specified mode is\n\
1952	reached. The default is @var{mode} which means no splitting.",
1953	machine_mode,
1954	(machine_mode),
1955	default_split_reduction)
1956
1957	/* Returns a mask of vector sizes to iterate over when auto-vectorizing
1958	after processing the preferred one derived from preferred_simd_mode. */
1959	DEFHOOK
1960	(autovectorize_vector_modes,
1961	"If using the mode returned by @code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE}\n\
1962	is not the only approach worth considering, this hook should add one mode to\n\
1963	@var{modes} for each useful alternative approach. These modes are then\n\
1964	passed to @code{TARGET_VECTORIZE_RELATED_MODE} to obtain the vector mode\n\
1965	for a given element mode.\n\
1966	\n\
1967	The modes returned in @var{modes} should use the smallest element mode\n\
1968	possible for the vectorization approach that they represent, preferring\n\
1969	integer modes over floating-poing modes in the event of a tie. The first\n\
1970	mode should be the @code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE} for its\n\
1971	element mode.\n\
1972	\n\
1973	If @var{all} is true, add suitable vector modes even when they are generally\n\
1974	not expected to be worthwhile.\n\
1975	\n\
1976	The hook returns a bitmask of flags that control how the modes in\n\
1977	@var{modes} are used. The flags are:\n\
1978	@table @code\n\
1979	@item VECT_COMPARE_COSTS\n\
1980	Tells the loop vectorizer to try all the provided modes and pick the one\n\
1981	with the lowest cost. By default the vectorizer will choose the first\n\
1982	mode that works.\n\
1983	@end table\n\
1984	\n\
1985	The hook does not need to do anything if the vector returned by\n\
1986	@code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE} is the only one relevant\n\
1987	for autovectorization. The default implementation adds no modes and\n\
1988	returns 0.",
1989	unsigned int,
1990	(vector_modes *modes, bool all),
1991	default_autovectorize_vector_modes)
1992
1993	DEFHOOK
1994	(related_mode,
1995	"If a piece of code is using vector mode @var{vector_mode} and also wants\n\
1996	to operate on elements of mode @var{element_mode}, return the vector mode\n\
1997	it should use for those elements. If @var{nunits} is nonzero, ensure that\n\
1998	the mode has exactly @var{nunits} elements, otherwise pick whichever vector\n\
1999	size pairs the most naturally with @var{vector_mode}. Return an empty\n\
2000	@code{opt_machine_mode} if there is no supported vector mode with the\n\
2001	required properties.\n\
2002	\n\
2003	There is no prescribed way of handling the case in which @var{nunits}\n\
2004	is zero. One common choice is to pick a vector mode with the same size\n\
2005	as @var{vector_mode}; this is the natural choice if the target has a\n\
2006	fixed vector size. Another option is to choose a vector mode with the\n\
2007	same number of elements as @var{vector_mode}; this is the natural choice\n\
2008	if the target has a fixed number of elements. Alternatively, the hook\n\
2009	might choose a middle ground, such as trying to keep the number of\n\
2010	elements as similar as possible while applying maximum and minimum\n\
2011	vector sizes.\n\
2012	\n\
2013	The default implementation uses @code{mode_for_vector} to find the\n\
2014	requested mode, returning a mode with the same size as @var{vector_mode}\n\
2015	when @var{nunits} is zero. This is the correct behavior for most targets.",
2016	opt_machine_mode,
2017	(machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits),
2018	default_vectorize_related_mode)
2019
2020	/* Function to get a target mode for a vector mask. */
2021	DEFHOOK
2022	(get_mask_mode,
2023	"Return the mode to use for a vector mask that holds one boolean\n\
2024	result for each element of vector mode @var{mode}. The returned mask mode\n\
2025	can be a vector of integers (class @code{MODE_VECTOR_INT}), a vector of\n\
2026	booleans (class @code{MODE_VECTOR_BOOL}) or a scalar integer (class\n\
2027	@code{MODE_INT}). Return an empty @code{opt_machine_mode} if no such\n\
2028	mask mode exists.\n\
2029	\n\
2030	The default implementation returns a @code{MODE_VECTOR_INT} with the\n\
2031	same size and number of elements as @var{mode}, if such a mode exists.",
2032	opt_machine_mode,
2033	(machine_mode mode),
2034	default_get_mask_mode)
2035
2036	/* Function to say whether a conditional operation is expensive when
2037	compared to non-masked operations. */
2038	DEFHOOK
2039	(conditional_operation_is_expensive,
2040	"This hook returns true if masked operation @var{ifn} (really of\n\
2041	type @code{internal_fn}) should be considered more expensive to use than\n\
2042	implementing the same operation without masking. GCC can then try to use\n\
2043	unconditional operations instead with extra selects.",
2044	bool,
2045	(unsigned ifn),
2046	default_conditional_operation_is_expensive)
2047
2048	/* Function to say whether a masked operation is expensive when the
2049	mask is all zeros. */
2050	DEFHOOK
2051	(empty_mask_is_expensive,
2052	"This hook returns true if masked internal function @var{ifn} (really of\n\
2053	type @code{internal_fn}) should be considered expensive when the mask is\n\
2054	all zeros. GCC can then try to branch around the instruction instead.",
2055	bool,
2056	(unsigned ifn),
2057	default_empty_mask_is_expensive)
2058
2059	/* Target builtin that implements vector gather operation. */
2060	DEFHOOK
2061	(builtin_gather,
2062	"Target builtin that implements vector gather operation. @var{mem_vectype}\n\
2063	is the vector type of the load and @var{index_type} is scalar type of\n\
2064	the index, scaled by @var{scale}.\n\
2065	The default is @code{NULL_TREE} which means to not vectorize gather\n\
2066	loads.",
2067	tree,
2068	(const_tree mem_vectype, const_tree index_type, int scale),
2069	NULL)
2070
2071	/* Target builtin that implements vector scatter operation. */
2072	DEFHOOK
2073	(builtin_scatter,
2074	"Target builtin that implements vector scatter operation. @var{vectype}\n\
2075	is the vector type of the store and @var{index_type} is scalar type of\n\
2076	the index, scaled by @var{scale}.\n\
2077	The default is @code{NULL_TREE} which means to not vectorize scatter\n\
2078	stores.",
2079	tree,
2080	(const_tree vectype, const_tree index_type, int scale),
2081	NULL)
2082
2083	/* Target function to initialize the cost model for a loop or block. */
2084	DEFHOOK
2085	(create_costs,
2086	"This hook should initialize target-specific data structures in preparation\n\
2087	for modeling the costs of vectorizing a loop or basic block. The default\n\
2088	allocates three unsigned integers for accumulating costs for the prologue,\n\
2089	body, and epilogue of the loop or basic block. If @var{loop_info} is\n\
2090	non-NULL, it identifies the loop being vectorized; otherwise a single block\n\
2091	is being vectorized. If @var{costing_for_scalar} is true, it indicates the\n\
2092	current cost model is for the scalar version of a loop or block; otherwise\n\
2093	it is for the vector version.",
2094	class vector_costs *,
2095	(vec_info *vinfo, bool costing_for_scalar),
2096	default_vectorize_create_costs)
2097
2098	HOOK_VECTOR_END (vectorize)
2099
2100	#undef HOOK_PREFIX
2101	#define HOOK_PREFIX "TARGET_"
2102
2103	DEFHOOK
2104	(preferred_else_value,
2105	"This hook returns the target's preferred final argument for a call\n\
2106	to conditional internal function @var{ifn} (really of type\n\
2107	@code{internal_fn}). @var{type} specifies the return type of the\n\
2108	function and @var{ops} are the operands to the conditional operation,\n\
2109	of which there are @var{nops}.\n\
2110	\n\
2111	For example, if @var{ifn} is @code{IFN_COND_ADD}, the hook returns\n\
2112	a value of type @var{type} that should be used when @samp{@var{ops}[0]}\n\
2113	and @samp{@var{ops}[1]} are conditionally added together.\n\
2114	\n\
2115	This hook is only relevant if the target supports conditional patterns\n\
2116	like @code{cond_add@var{m}}. The default implementation returns a zero\n\
2117	constant of type @var{type}.",
2118	tree,
2119	(unsigned ifn, tree type, unsigned nops, tree *ops),
2120	default_preferred_else_value)
2121
2122	DEFHOOK
2123	(record_offload_symbol,
2124	"Used when offloaded functions are seen in the compilation unit and no named\n\
2125	sections are available. It is called once for each symbol that must be\n\
2126	recorded in the offload function and variable table.",
2127	void, (tree),
2128	hook_void_tree)
2129
2130	DEFHOOKPOD
2131	(absolute_biggest_alignment,
2132	"If defined, this target hook specifies the absolute biggest alignment\n\
2133	that a type or variable can have on this machine, otherwise,\n\
2134	@code{BIGGEST_ALIGNMENT} is used.",
2135	HOST_WIDE_INT, BIGGEST_ALIGNMENT)
2136
2137	/* Allow target specific overriding of option settings after options have
2138	been changed by an attribute or pragma or when it is reset at the
2139	end of the code affected by an attribute or pragma. */
2140	DEFHOOK
2141	(override_options_after_change,
2142	"This target function is similar to the hook @code{TARGET_OPTION_OVERRIDE}\n\
2143	but is called when the optimize level is changed via an attribute or\n\
2144	pragma or when it is reset at the end of the code affected by the\n\
2145	attribute or pragma. It is not called at the beginning of compilation\n\
2146	when @code{TARGET_OPTION_OVERRIDE} is called so if you want to perform these\n\
2147	actions then, you should have @code{TARGET_OPTION_OVERRIDE} call\n\
2148	@code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}.",
2149	void, (void),
2150	hook_void_void)
2151
2152	DEFHOOK
2153	(offload_options,
2154	"Used when writing out the list of options into an LTO file. It should\n\
2155	translate any relevant target-specific options (such as the ABI in use)\n\
2156	into one of the @option{-foffload} options that exist as a common interface\n\
2157	to express such options. It should return a string containing these options,\n\
2158	separated by spaces, which the caller will free.\n",
2159	char *, (void), hook_charptr_void_null)
2160
2161	DEFHOOK_UNDOC
2162	(eh_return_filter_mode,
2163	"Return machine mode for filter value.",
2164	scalar_int_mode, (void),
2165	default_eh_return_filter_mode)
2166
2167	/* Return machine mode for libgcc expanded cmp instructions. */
2168	DEFHOOK
2169	(libgcc_cmp_return_mode,
2170	"This target hook should return the mode to be used for the return value\n\
2171	of compare instructions expanded to libgcc calls. If not defined\n\
2172	@code{word_mode} is returned which is the right choice for a majority of\n\
2173	targets.",
2174	scalar_int_mode, (void),
2175	default_libgcc_cmp_return_mode)
2176
2177	/* Return machine mode for libgcc expanded shift instructions. */
2178	DEFHOOK
2179	(libgcc_shift_count_mode,
2180	"This target hook should return the mode to be used for the shift count operand\n\
2181	of shift instructions expanded to libgcc calls. If not defined\n\
2182	@code{word_mode} is returned which is the right choice for a majority of\n\
2183	targets.",
2184	scalar_int_mode, (void),
2185	default_libgcc_shift_count_mode)
2186
2187	/* Return machine mode to be used for _Unwind_Word type. */
2188	DEFHOOK
2189	(unwind_word_mode,
2190	"Return machine mode to be used for @code{_Unwind_Word} type.\n\
2191	The default is to use @code{word_mode}.",
2192	scalar_int_mode, (void),
2193	default_unwind_word_mode)
2194
2195	/* Given two decls, merge their attributes and return the result. */
2196	DEFHOOK
2197	(merge_decl_attributes,
2198	"Define this target hook if the merging of decl attributes needs special\n\
2199	handling. If defined, the result is a list of the combined\n\
2200	@code{DECL_ATTRIBUTES} of @var{olddecl} and @var{newdecl}.\n\
2201	@var{newdecl} is a duplicate declaration of @var{olddecl}. Examples of\n\
2202	when this is needed are when one attribute overrides another, or when an\n\
2203	attribute is nullified by a subsequent definition. This function may\n\
2204	call @code{merge_attributes} to handle machine-independent merging.\n\
2205	\n\
2206	@findex TARGET_DLLIMPORT_DECL_ATTRIBUTES\n\
2207	If the only target-specific handling you require is @samp{dllimport}\n\
2208	for Microsoft Windows targets, you should define the macro\n\
2209	@code{TARGET_DLLIMPORT_DECL_ATTRIBUTES} to @code{1}. The compiler\n\
2210	will then define a function called\n\
2211	@code{merge_dllimport_decl_attributes} which can then be defined as\n\
2212	the expansion of @code{TARGET_MERGE_DECL_ATTRIBUTES}. You can also\n\
2213	add @code{handle_dll_attribute} in the attribute table for your port\n\
2214	to perform initial processing of the @samp{dllimport} and\n\
2215	@samp{dllexport} attributes. This is done in @file{i386/cygwin.h} and\n\
2216	@file{i386/i386.cc}, for example.",
2217	tree, (tree olddecl, tree newdecl),
2218	merge_decl_attributes)
2219
2220	/* Given two types, merge their attributes and return the result. */
2221	DEFHOOK
2222	(merge_type_attributes,
2223	"Define this target hook if the merging of type attributes needs special\n\
2224	handling. If defined, the result is a list of the combined\n\
2225	@code{TYPE_ATTRIBUTES} of @var{type1} and @var{type2}. It is assumed\n\
2226	that @code{comptypes} has already been called and returned 1. This\n\
2227	function may call @code{merge_attributes} to handle machine-independent\n\
2228	merging.",
2229	tree, (tree type1, tree type2),
2230	merge_type_attributes)
2231
2232	/* Table of machine attributes and functions to handle them.
2233	Ignored if empty. */
2234	DEFHOOKPOD
2235	(attribute_table,
2236	"If defined, this target hook provides an array of\n\
2237	@samp{scoped_attribute_spec}s (defined in @file{attribs.h}) that specify the\n\
2238	machine-specific attributes for this target. The information includes some\n\
2239	of the restrictions on the entities to which these attributes are applied\n\
2240	and the arguments that the attributes take.\n\
2241	\n\
2242	In C and C++, these attributes are associated with two syntaxes:\n\
2243	the traditional GNU @code{__attribute__} syntax and the standard\n\
2244	@samp{[[]]} syntax. Attributes that support the GNU syntax must be\n\
2245	placed in the @code{gnu} namespace. Such attributes can then also be\n\
2246	written @samp{[[gnu::@dots{}]]}. Attributes that use only the standard\n\
2247	syntax should be placed in whichever namespace the attribute specification\n\
2248	requires. For example, a target might choose to support vendor-specific\n\
2249	@samp{[[]]} attributes that the vendor places in their own namespace.\n\
2250	\n\
2251	Targets that only define attributes in the @code{gnu} namespace\n\
2252	can uase the following shorthand to define the table:\n\
2253	\n\
2254	@smallexample\n\
2255	TARGET_GNU_ATTRIBUTES (@var{cpu_attribute_table}, @{\n\
2256	@{ \"@var{attribute1}\", @dots{} @},\n\
2257	@{ \"@var{attribute2}\", @dots{} @},\n\
2258	@dots{},\n\
2259	@{ \"@var{attributen}\", @dots{} @},\n\
2260	@});\n\
2261	@end smallexample",
2262	array_slice<const struct scoped_attribute_specs *const>,)
2263
2264	/* Return true iff attribute NAME expects a plain identifier as its first
2265	argument. */
2266	DEFHOOK
2267	(attribute_takes_identifier_p,
2268	"If defined, this target hook is a function which returns true if the\n\
2269	machine-specific attribute named @var{name} expects an identifier\n\
2270	given as its first argument to be passed on as a plain identifier, not\n\
2271	subjected to name lookup. If this is not defined, the default is\n\
2272	false for all machine-specific attributes.",
2273	bool, (const_tree name),
2274	hook_bool_const_tree_false)
2275
2276	/* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
2277	one if they are compatible and two if they are nearly compatible
2278	(which causes a warning to be generated). */
2279	DEFHOOK
2280	(comp_type_attributes,
2281	"If defined, this target hook is a function which returns zero if the attributes on\n\
2282	@var{type1} and @var{type2} are incompatible, one if they are compatible,\n\
2283	and two if they are nearly compatible (which causes a warning to be\n\
2284	generated). If this is not defined, machine-specific attributes are\n\
2285	supposed always to be compatible.",
2286	int, (const_tree type1, const_tree type2),
2287	hook_int_const_tree_const_tree_1)
2288
2289	/* Assign default attributes to the newly defined TYPE. */
2290	DEFHOOK
2291	(set_default_type_attributes,
2292	"If defined, this target hook is a function which assigns default attributes to\n\
2293	the newly defined @var{type}.",
2294	void, (tree type),
2295	hook_void_tree)
2296
2297	/* Insert attributes on the newly created DECL. */
2298	DEFHOOK
2299	(insert_attributes,
2300	"Define this target hook if you want to be able to add attributes to a decl\n\
2301	when it is being created. This is normally useful for back ends which\n\
2302	wish to implement a pragma by using the attributes which correspond to\n\
2303	the pragma's effect. The @var{node} argument is the decl which is being\n\
2304	created. The @var{attr_ptr} argument is a pointer to the attribute list\n\
2305	for this decl. The list itself should not be modified, since it may be\n\
2306	shared with other decls, but attributes may be chained on the head of\n\
2307	the list and @code{*@var{attr_ptr}} modified to point to the new\n\
2308	attributes, or a copy of the list may be made if further changes are\n\
2309	needed.",
2310	void, (tree node, tree *attr_ptr),
2311	hook_void_tree_treeptr)
2312
2313	/* Perform additional target-specific processing of generic attributes. */
2314	DEFHOOK
2315	(handle_generic_attribute,
2316	"Define this target hook if you want to be able to perform additional\n\
2317	target-specific processing of an attribute which is handled generically\n\
2318	by a front end. The arguments are the same as those which are passed to\n\
2319	attribute handlers. So far this only affects the @var{noinit} and\n\
2320	@var{section} attribute.",
2321	tree, (tree *node, tree name, tree args, int flags, bool *no_add_attrs),
2322	hook_tree_treeptr_tree_tree_int_boolptr_null)
2323
2324	/* Return true if FNDECL (which has at least one machine attribute)
2325	can be inlined despite its machine attributes, false otherwise. */
2326	DEFHOOK
2327	(function_attribute_inlinable_p,
2328	"@cindex inlining\n\
2329	This target hook returns @code{false} if the target-specific attributes on\n\
2330	@var{fndecl} always block it getting inlined, @code{true} otherwise. By\n\
2331	default, if a function has a target specific attribute attached to it, it\n\
2332	will not be inlined.",
2333	bool, (const_tree fndecl),
2334	hook_bool_const_tree_false)
2335
2336	/* Return true if bitfields in RECORD_TYPE should follow the
2337	Microsoft Visual C++ bitfield layout rules. */
2338	DEFHOOK
2339	(ms_bitfield_layout_p,
2340	"This target hook returns @code{true} if bit-fields in the given\n\
2341	@var{record_type} are to be laid out following the rules of Microsoft\n\
2342	Visual C/C++, namely: (i) a bit-field won't share the same storage\n\
2343	unit with the previous bit-field if their underlying types have\n\
2344	different sizes, and the bit-field will be aligned to the highest\n\
2345	alignment of the underlying types of itself and of the previous\n\
2346	bit-field; (ii) a zero-sized bit-field will affect the alignment of\n\
2347	the whole enclosing structure, even if it is unnamed; except that\n\
2348	(iii) a zero-sized bit-field will be disregarded unless it follows\n\
2349	another bit-field of nonzero size. If this hook returns @code{true},\n\
2350	other macros that control bit-field layout are ignored.\n\
2351	\n\
2352	When a bit-field is inserted into a packed record, the whole size\n\
2353	of the underlying type is used by one or more same-size adjacent\n\
2354	bit-fields (that is, if its long:3, 32 bits is used in the record,\n\
2355	and any additional adjacent long bit-fields are packed into the same\n\
2356	chunk of 32 bits. However, if the size changes, a new field of that\n\
2357	size is allocated). In an unpacked record, this is the same as using\n\
2358	alignment, but not equivalent when packing.\n\
2359	\n\
2360	If both MS bit-fields and @samp{__attribute__((packed))} are used,\n\
2361	the latter will take precedence. If @samp{__attribute__((packed))} is\n\
2362	used on a single field when MS bit-fields are in use, it will take\n\
2363	precedence for that field, but the alignment of the rest of the structure\n\
2364	may affect its placement.",
2365	bool, (const_tree record_type),
2366	hook_bool_const_tree_false)
2367
2368	/* For now this is only an interface to WORDS_BIG_ENDIAN for
2369	target-independent code like the front ends, need performance testing
2370	before switching completely to the target hook. */
2371	DEFHOOK_UNDOC
2372	(words_big_endian,
2373	"",
2374	bool, (void),
2375	targhook_words_big_endian)
2376
2377	/* Likewise for FLOAT_WORDS_BIG_ENDIAN. */
2378	DEFHOOK_UNDOC
2379	(float_words_big_endian,
2380	"",
2381	bool, (void),
2382	targhook_float_words_big_endian)
2383
2384	DEFHOOK
2385	(float_exceptions_rounding_supported_p,
2386	"Returns true if the target supports IEEE 754 floating-point exceptions\n\
2387	and rounding modes, false otherwise. This is intended to relate to the\n\
2388	@code{float} and @code{double} types, but not necessarily @code{long double}.\n\
2389	By default, returns true if the @code{adddf3} instruction pattern is\n\
2390	available and false otherwise, on the assumption that hardware floating\n\
2391	point supports exceptions and rounding modes but software floating point\n\
2392	does not.",
2393	bool, (void),
2394	default_float_exceptions_rounding_supported_p)
2395
2396	/* True if the target supports decimal floating point. */
2397	DEFHOOK
2398	(decimal_float_supported_p,
2399	"Returns true if the target supports decimal floating point.",
2400	bool, (void),
2401	default_decimal_float_supported_p)
2402
2403	/* True if the target supports fixed-point. */
2404	DEFHOOK
2405	(fixed_point_supported_p,
2406	"Returns true if the target supports fixed-point arithmetic.",
2407	bool, (void),
2408	default_fixed_point_supported_p)
2409
2410	/* Return true if anonymous bitfields affect structure alignment. */
2411	DEFHOOK
2412	(align_anon_bitfield,
2413	"When @code{PCC_BITFIELD_TYPE_MATTERS} is true this hook will determine\n\
2414	whether unnamed bitfields affect the alignment of the containing\n\
2415	structure. The hook should return true if the structure should inherit\n\
2416	the alignment requirements of an unnamed bitfield's type.",
2417	bool, (void),
2418	hook_bool_void_false)
2419
2420	/* Return true if volatile bitfields should use the narrowest type possible.
2421	Return false if they should use the container type. */
2422	DEFHOOK
2423	(narrow_volatile_bitfield,
2424	"This target hook should return @code{true} if accesses to volatile bitfields\n\
2425	should use the narrowest mode possible. It should return @code{false} if\n\
2426	these accesses should use the bitfield container type.\n\
2427	\n\
2428	The default is @code{false}.",
2429	bool, (void),
2430	hook_bool_void_false)
2431
2432	/* Set up target-specific built-in functions. */
2433	DEFHOOK
2434	(init_builtins,
2435	"Define this hook if you have any machine-specific built-in functions\n\
2436	that need to be defined. It should be a function that performs the\n\
2437	necessary setup.\n\
2438	\n\
2439	Machine specific built-in functions can be useful to expand special machine\n\
2440	instructions that would otherwise not normally be generated because\n\
2441	they have no equivalent in the source language (for example, SIMD vector\n\
2442	instructions or prefetch instructions).\n\
2443	\n\
2444	To create a built-in function, call the function\n\
2445	@code{lang_hooks.builtin_function}\n\
2446	which is defined by the language front end. You can use any type nodes set\n\
2447	up by @code{build_common_tree_nodes};\n\
2448	only language front ends that use those two functions will call\n\
2449	@samp{TARGET_INIT_BUILTINS}.",
2450	void, (void),
2451	hook_void_void)
2452
2453	/* Initialize (if INITIALIZE_P is true) and return the target-specific
2454	built-in function decl for CODE.
2455	Return NULL if that is not possible. Return error_mark_node if CODE
2456	is outside of the range of valid target builtin function codes. */
2457	DEFHOOK
2458	(builtin_decl,
2459	"Define this hook if you have any machine-specific built-in functions\n\
2460	that need to be defined. It should be a function that returns the\n\
2461	builtin function declaration for the builtin function code @var{code}.\n\
2462	If there is no such builtin and it cannot be initialized at this time\n\
2463	if @var{initialize_p} is true the function should return @code{NULL_TREE}.\n\
2464	If @var{code} is out of range the function should return\n\
2465	@code{error_mark_node}.",
2466	tree, (unsigned code, bool initialize_p), NULL)
2467
2468	/* Expand a target-specific builtin. */
2469	DEFHOOK
2470	(expand_builtin,
2471	"\n\
2472	Expand a call to a machine specific built-in function that was set up by\n\
2473	@samp{TARGET_INIT_BUILTINS}. @var{exp} is the expression for the\n\
2474	function call; the result should go to @var{target} if that is\n\
2475	convenient, and have mode @var{mode} if that is convenient.\n\
2476	@var{subtarget} may be used as the target for computing one of\n\
2477	@var{exp}'s operands. @var{ignore} is nonzero if the value is to be\n\
2478	ignored. This function should return the result of the call to the\n\
2479	built-in function.",
2480	rtx,
2481	(tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore),
2482	default_expand_builtin)
2483
2484	/* Select a replacement for a target-specific builtin. This is done
2485	*before* regular type checking, and so allows the target to
2486	implement a crude form of function overloading. The result is a
2487	complete expression that implements the operation. PARAMS really
2488	has type VEC(tree,gc)*, but we don't want to include tree.h here. */
2489	DEFHOOK
2490	(resolve_overloaded_builtin,
2491	"Select a replacement for a machine specific built-in function that\n\
2492	was set up by @samp{TARGET_INIT_BUILTINS}. This is done\n\
2493	@emph{before} regular type checking, and so allows the target to\n\
2494	implement a crude form of function overloading. @var{fndecl} is the\n\
2495	declaration of the built-in function. @var{arglist} is the list of\n\
2496	arguments passed to the built-in function. The result is a\n\
2497	complete expression that implements the operation, usually\n\
2498	another @code{CALL_EXPR}.\n\
2499	@var{arglist} really has type @samp{VEC(tree,gc)*}\n\
2500	@var{complain} is a boolean indicating whether invalid operations\n\
2501	should emit errors. This is set to @code{false} when the C++ templating\n\
2502	context expects that errors should not be emitted (i.e. SFINAE).",
2503	tree, (location_t loc, tree fndecl, void *arglist, bool complain), NULL)
2504
2505	DEFHOOK
2506	(check_builtin_call,
2507	"Perform semantic checking on a call to a machine-specific built-in\n\
2508	function after its arguments have been constrained to the function\n\
2509	signature. Return true if the call is valid, otherwise report an error\n\
2510	and return false.\n\
2511	\n\
2512	This hook is called after @code{TARGET_RESOLVE_OVERLOADED_BUILTIN}.\n\
2513	The call was originally to built-in function @var{orig_fndecl},\n\
2514	but after the optional @code{TARGET_RESOLVE_OVERLOADED_BUILTIN}\n\
2515	step is now to built-in function @var{fndecl}. @var{loc} is the\n\
2516	location of the call and @var{args} is an array of function arguments,\n\
2517	of which there are @var{nargs}. @var{arg_loc} specifies the location\n\
2518	of each argument. @var{complain} is a boolean indicating whether invalid\n\
2519	arguments should emitm errors. This is set to @code{false} when the C++\n\
2520	templating context expects that errors should not be emitted (i.e. SFINAE).",
2521	bool, (location_t loc, vec<location_t> arg_loc, tree fndecl,
2522	tree orig_fndecl, unsigned int nargs, tree *args, bool complain),
2523	NULL)
2524
2525	/* Fold a target-specific builtin to a tree valid for both GIMPLE
2526	and GENERIC. */
2527	DEFHOOK
2528	(fold_builtin,
2529	"Fold a call to a machine specific built-in function that was set up by\n\
2530	@samp{TARGET_INIT_BUILTINS}. @var{fndecl} is the declaration of the\n\
2531	built-in function. @var{n_args} is the number of arguments passed to\n\
2532	the function; the arguments themselves are pointed to by @var{argp}.\n\
2533	The result is another tree, valid for both GIMPLE and GENERIC,\n\
2534	containing a simplified expression for the call's result. If\n\
2535	@var{ignore} is true the value will be ignored.",
2536	tree, (tree fndecl, int n_args, tree *argp, bool ignore),
2537	hook_tree_tree_int_treep_bool_null)
2538
2539	/* Fold a target-specific builtin to a valid GIMPLE tree. */
2540	DEFHOOK
2541	(gimple_fold_builtin,
2542	"Fold a call to a machine specific built-in function that was set up\n\
2543	by @samp{TARGET_INIT_BUILTINS}. @var{gsi} points to the gimple\n\
2544	statement holding the function call. Returns true if any change\n\
2545	was made to the GIMPLE stream.",
2546	bool, (gimple_stmt_iterator *gsi),
2547	hook_bool_gsiptr_false)
2548
2549	/* Target hook is used to compare the target attributes in two functions to
2550	determine which function's features get higher priority. This is used
2551	during function multi-versioning to figure out the order in which two
2552	versions must be dispatched. A function version with a higher priority
2553	is checked for dispatching earlier. DECL1 and DECL2 are
2554	the two function decls that will be compared. It returns positive value
2555	if DECL1 is higher priority, negative value if DECL2 is higher priority
2556	and 0 if they are the same. */
2557	DEFHOOK
2558	(compare_version_priority,
2559	"This hook is used to compare the target attributes in two functions to\n\
2560	determine which function's features get higher priority. This is used\n\
2561	during function multi-versioning to figure out the order in which two\n\
2562	versions must be dispatched. A function version with a higher priority\n\
2563	is checked for dispatching earlier. @var{decl1} and @var{decl2} are\n\
2564	the two function decls that will be compared.",
2565	int, (tree decl1, tree decl2), NULL)
2566
2567	/* Target hook is used to generate the dispatcher logic to invoke the right
2568	function version at run-time for a given set of function versions.
2569	ARG points to the callgraph node of the dispatcher function whose body
2570	must be generated. */
2571	DEFHOOK
2572	(generate_version_dispatcher_body,
2573	"This hook is used to generate the dispatcher logic to invoke the right\n\
2574	function version at run-time for a given set of function versions.\n\
2575	@var{arg} points to the callgraph node of the dispatcher function whose\n\
2576	body must be generated.",
2577	tree, (void *arg), NULL)
2578
2579	/* Target hook is used to get the dispatcher function for a set of function
2580	versions. The dispatcher function is called to invoke the right function
2581	version at run-time. DECL is one version from a set of semantically
2582	identical versions. */
2583	DEFHOOK
2584	(get_function_versions_dispatcher,
2585	"This hook is used to get the dispatcher function for a set of function\n\
2586	versions. The dispatcher function is called to invoke the right function\n\
2587	version at run-time. @var{decl} is one version from a set of semantically\n\
2588	identical versions.",
2589	tree, (void *decl), NULL)
2590
2591	/* Returns a code for a target-specific builtin that implements
2592	reciprocal of a target-specific function, or NULL_TREE if not available. */
2593	DEFHOOK
2594	(builtin_reciprocal,
2595	"This hook should return the DECL of a function that implements the\n\
2596	reciprocal of the machine-specific builtin function @var{fndecl}, or\n\
2597	@code{NULL_TREE} if such a function is not available.",
2598	tree, (tree fndecl),
2599	default_builtin_reciprocal)
2600
2601	/* For a vendor-specific TYPE, return a pointer to a statically-allocated
2602	string containing the C++ mangling for TYPE. In all other cases, return
2603	NULL. */
2604	DEFHOOK
2605	(mangle_type,
2606	"If your target defines any fundamental types, or any types your target\n\
2607	uses should be mangled differently from the default, define this hook\n\
2608	to return the appropriate encoding for these types as part of a C++\n\
2609	mangled name. The @var{type} argument is the tree structure representing\n\
2610	the type to be mangled. The hook may be applied to trees which are\n\
2611	not target-specific fundamental types; it should return @code{NULL}\n\
2612	for all such types, as well as arguments it does not recognize. If the\n\
2613	return value is not @code{NULL}, it must point to a statically-allocated\n\
2614	string constant.\n\
2615	\n\
2616	Target-specific fundamental types might be new fundamental types or\n\
2617	qualified versions of ordinary fundamental types. Encode new\n\
2618	fundamental types as @samp{@w{u @var{n} @var{name}}}, where @var{name}\n\
2619	is the name used for the type in source code, and @var{n} is the\n\
2620	length of @var{name} in decimal. Encode qualified versions of\n\
2621	ordinary types as @samp{@w{U @var{n} @var{name} @var{code}}}, where\n\
2622	@var{name} is the name used for the type qualifier in source code,\n\
2623	@var{n} is the length of @var{name} as above, and @var{code} is the\n\
2624	code used to represent the unqualified version of this type. (See\n\
2625	@code{write_builtin_type} in @file{cp/mangle.cc} for the list of\n\
2626	codes.) In both cases the spaces are for clarity; do not include any\n\
2627	spaces in your string.\n\
2628	\n\
2629	This hook is applied to types prior to typedef resolution. If the mangled\n\
2630	name for a particular type depends only on that type's main variant, you\n\
2631	can perform typedef resolution yourself using @code{TYPE_MAIN_VARIANT}\n\
2632	before mangling.\n\
2633	\n\
2634	The default version of this hook always returns @code{NULL}, which is\n\
2635	appropriate for a target that does not define any new fundamental\n\
2636	types.",
2637	const char *, (const_tree type),
2638	hook_constcharptr_const_tree_null)
2639
2640	/* Temporarily add conditional target specific types for the purpose of
2641	emitting C++ fundamental type tinfos. */
2642	DEFHOOK
2643	(emit_support_tinfos,
2644	"If your target defines any fundamental types which depend on ISA flags,\n\
2645	they might need C++ tinfo symbols in libsupc++/libstdc++ regardless of\n\
2646	ISA flags the library is compiled with.\n\
2647	This hook allows creating tinfo symbols even for those cases, by temporarily\n\
2648	creating each corresponding fundamental type trees, calling the\n\
2649	@var{callback} function on it and setting the type back to @code{nullptr}.",
2650	void, (emit_support_tinfos_callback callback),
2651	default_emit_support_tinfos)
2652
2653	/* Make any adjustments to libfunc names needed for this target. */
2654	DEFHOOK
2655	(init_libfuncs,
2656	"This hook should declare additional library routines or rename\n\
2657	existing ones, using the functions @code{set_optab_libfunc} and\n\
2658	@code{init_one_libfunc} defined in @file{optabs.cc}.\n\
2659	@code{init_optabs} calls this macro after initializing all the normal\n\
2660	library routines.\n\
2661	\n\
2662	The default is to do nothing. Most ports don't need to define this hook.",
2663	void, (void),
2664	hook_void_void)
2665
2666	/* Add a __gnu_ prefix to library functions rather than just __. */
2667	DEFHOOKPOD
2668	(libfunc_gnu_prefix,
2669	"If false (the default), internal library routines start with two\n\
2670	underscores. If set to true, these routines start with @code{__gnu_}\n\
2671	instead. E.g., @code{__muldi3} changes to @code{__gnu_muldi3}. This\n\
2672	currently only affects functions defined in @file{libgcc2.c}. If this\n\
2673	is set to true, the @file{tm.h} file must also\n\
2674	@code{#define LIBGCC2_GNU_PREFIX}.",
2675	bool, false)
2676
2677	/* Given a decl, a section name, and whether the decl initializer
2678	has relocs, choose attributes for the section. */
2679	/* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION. */
2680	DEFHOOK
2681	(section_type_flags,
2682	"Choose a set of section attributes for use by @code{TARGET_ASM_NAMED_SECTION}\n\
2683	based on a variable or function decl, a section name, and whether or not the\n\
2684	declaration's initializer may contain runtime relocations. @var{decl} may be\n\
2685	null, in which case read-write data should be assumed.\n\
2686	\n\
2687	The default version of this function handles choosing code vs data,\n\
2688	read-only vs read-write data, and @code{flag_pic}. You should only\n\
2689	need to override this if your target has special flags that might be\n\
2690	set via @code{__attribute__}.",
2691	unsigned int, (tree decl, const char *name, int reloc),
2692	default_section_type_flags)
2693
2694	DEFHOOK
2695	(libc_has_function,
2696	"This hook determines whether a function from a class of functions\n\
2697	@var{fn_class} is present in the target C library. If @var{type} is NULL,\n\
2698	the caller asks for support for all standard (float, double, long double)\n\
2699	types. If @var{type} is non-NULL, the caller asks for support for a\n\
2700	specific type.",
2701	bool, (enum function_class fn_class, tree type),
2702	default_libc_has_function)
2703
2704	DEFHOOK
2705	(libc_has_fast_function,
2706	"This hook determines whether a function from a class of functions\n\
2707	@code{(enum function_class)}@var{fcode} has a fast implementation.",
2708	bool, (int fcode),
2709	default_libc_has_fast_function)
2710
2711	DEFHOOK
2712	(fortify_source_default_level,
2713	"This hook determines what value _FORTIFY_SOURCE will be set to when using\n\
2714	the command-line option -fhardened.",
2715	unsigned, (void),
2716	default_fortify_source_default_level)
2717
2718	DEFHOOK
2719	(libm_function_max_error,
2720	"This hook determines expected maximum errors for math functions measured\n\
2721	in ulps (units of the last place). 0 means 0.5ulps precision (correctly\n\
2722	rounded). ~0U means unknown errors. The @code{combined_fn} @var{cfn}\n\
2723	argument should identify just which math built-in function it is rather than\n\
2724	its variant, @var{mode} the variant in terms of floating-point machine mode.\n\
2725	The hook should also take into account @code{flag_rounding_math} whether it\n\
2726	is maximum error just in default rounding mode, or in all possible rounding\n\
2727	modes. @var{boundary_p} is @code{true} for maximum errors on intrinsic math\n\
2728	boundaries of functions rather than errors inside of the usual result ranges\n\
2729	of the functions. E.g.@ the sin/cos function finite result is in between\n\
2730	-1.0 and 1.0 inclusive, with @var{boundary_p} true the function returns how\n\
2731	many ulps below or above those boundaries result could be.",
2732	unsigned, (unsigned cfn, machine_mode mode, bool boundary_p),
2733	default_libm_function_max_error)
2734
2735	/* True if new jumps cannot be created, to replace existing ones or
2736	not, at the current point in the compilation. */
2737	DEFHOOK
2738	(cannot_modify_jumps_p,
2739	"This target hook returns @code{true} past the point in which new jump\n\
2740	instructions could be created. On machines that require a register for\n\
2741	every jump such as the SHmedia ISA of SH5, this point would typically be\n\
2742	reload, so this target hook should be defined to a function such as:\n\
2743	\n\
2744	@smallexample\n\
2745	static bool\n\
2746	cannot_modify_jumps_past_reload_p ()\n\
2747	@{\n\
2748	return (reload_completed || reload_in_progress);\n\
2749	@}\n\
2750	@end smallexample",
2751	bool, (void),
2752	hook_bool_void_false)
2753
2754	/* True if FOLLOWER may be modified to follow FOLLOWEE. */
2755	DEFHOOK
2756	(can_follow_jump,
2757	"FOLLOWER and FOLLOWEE are JUMP_INSN instructions;\n\
2758	return true if FOLLOWER may be modified to follow FOLLOWEE;\n\
2759	false, if it can't.\n\
2760	For example, on some targets, certain kinds of branches can't be made to\n\
2761	follow through a hot/cold partitioning.",
2762	bool, (const rtx_insn *follower, const rtx_insn *followee),
2763	hook_bool_const_rtx_insn_const_rtx_insn_true)
2764
2765	/* Return true if the target supports conditional execution. */
2766	DEFHOOK
2767	(have_conditional_execution,
2768	"This target hook returns true if the target supports conditional execution.\n\
2769	This target hook is required only when the target has several different\n\
2770	modes and they have different conditional execution capability, such as ARM.",
2771	bool, (void),
2772	default_have_conditional_execution)
2773
2774	DEFHOOK
2775	(gen_ccmp_first,
2776	"This function prepares to emit a comparison insn for the first compare in a\n\
2777	sequence of conditional comparisions. It returns an appropriate comparison\n\
2778	with @code{CC} for passing to @code{gen_ccmp_next} or @code{cbranch_optab}.\n\
2779	The insns to prepare the compare are saved in @var{prep_seq} and the compare\n\
2780	insns are saved in @var{gen_seq}. They will be emitted when all the\n\
2781	compares in the conditional comparision are generated without error.\n\
2782	@var{code} is the @code{rtx_code} of the compare for @var{op0} and @var{op1}.",
2783	rtx, (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx_code code, tree op0, tree op1),
2784	NULL)
2785
2786	DEFHOOK
2787	(gen_ccmp_next,
2788	"This function prepares to emit a conditional comparison within a sequence\n\
2789	of conditional comparisons. It returns an appropriate comparison with\n\
2790	@code{CC} for passing to @code{gen_ccmp_next} or @code{cbranch_optab}.\n\
2791	The insns to prepare the compare are saved in @var{prep_seq} and the compare\n\
2792	insns are saved in @var{gen_seq}. They will be emitted when all the\n\
2793	compares in the conditional comparision are generated without error. The\n\
2794	@var{prev} expression is the result of a prior call to @code{gen_ccmp_first}\n\
2795	or @code{gen_ccmp_next}. It may return @code{NULL} if the combination of\n\
2796	@var{prev} and this comparison is not supported, otherwise the result must\n\
2797	be appropriate for passing to @code{gen_ccmp_next} or @code{cbranch_optab}.\n\
2798	@var{code} is the @code{rtx_code} of the compare for @var{op0} and @var{op1}.\n\
2799	@var{bit_code} is @code{AND} or @code{IOR}, which is the op on the compares.",
2800	rtx, (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, rtx_code cmp_code, tree op0, tree op1, rtx_code bit_code),
2801	NULL)
2802
2803	/* Return true if the target supports conditional compare. */
2804	DEFHOOK
2805	(have_ccmp,
2806	"This target hook returns true if the target supports conditional compare.\n\
2807	This target hook is required only when the ccmp support is conditionally\n\
2808	enabled, such as in response to command-line flags. The default implementation\n\
2809	returns true iff @code{TARGET_GEN_CCMP_FIRST} is defined.",
2810	bool, (void),
2811	default_have_ccmp)
2812
2813	/* Return a new value for loop unroll size. */
2814	DEFHOOK
2815	(loop_unroll_adjust,
2816	"This target hook returns a new value for the number of times @var{loop}\n\
2817	should be unrolled. The parameter @var{nunroll} is the number of times\n\
2818	the loop is to be unrolled. The parameter @var{loop} is a pointer to\n\
2819	the loop, which is going to be checked for unrolling. This target hook\n\
2820	is required only when the target has special constraints like maximum\n\
2821	number of memory accesses.",
2822	unsigned, (unsigned nunroll, class loop *loop),
2823	NULL)
2824
2825	/* True if X is a legitimate MODE-mode immediate operand. */
2826	DEFHOOK
2827	(legitimate_constant_p,
2828	"This hook returns true if @var{x} is a legitimate constant for a\n\
2829	@var{mode}-mode immediate operand on the target machine. You can assume that\n\
2830	@var{x} satisfies @code{CONSTANT_P}, so you need not check this.\n\
2831	\n\
2832	The default definition returns true.",
2833	bool, (machine_mode mode, rtx x),
2834	hook_bool_mode_rtx_true)
2835
2836	/* True if X is a TLS operand whose value should be pre-computed. */
2837	DEFHOOK
2838	(precompute_tls_p,
2839	"This hook returns true if @var{x} is a TLS operand on the target\n\
2840	machine that should be pre-computed when used as the argument in a call.\n\
2841	You can assume that @var{x} satisfies @code{CONSTANT_P}, so you need not \n\
2842	check this.\n\
2843	\n\
2844	The default definition returns false.",
2845	bool, (machine_mode mode, rtx x),
2846	hook_bool_mode_rtx_false)
2847
2848	/* True if the constant X cannot be placed in the constant pool. */
2849	DEFHOOK
2850	(cannot_force_const_mem,
2851	"This hook should return true if @var{x} is of a form that cannot (or\n\
2852	should not) be spilled to the constant pool. @var{mode} is the mode\n\
2853	of @var{x}.\n\
2854	\n\
2855	The default version of this hook returns false.\n\
2856	\n\
2857	The primary reason to define this hook is to prevent reload from\n\
2858	deciding that a non-legitimate constant would be better reloaded\n\
2859	from the constant pool instead of spilling and reloading a register\n\
2860	holding the constant. This restriction is often true of addresses\n\
2861	of TLS symbols for various targets.",
2862	bool, (machine_mode mode, rtx x),
2863	hook_bool_mode_rtx_false)
2864
2865	DEFHOOK_UNDOC
2866	(cannot_copy_insn_p,
2867	"True if the insn @var{x} cannot be duplicated.",
2868	bool, (rtx_insn *), NULL)
2869
2870	/* True if X is considered to be commutative. */
2871	DEFHOOK
2872	(commutative_p,
2873	"This target hook returns @code{true} if @var{x} is considered to be commutative.\n\
2874	Usually, this is just COMMUTATIVE_P (@var{x}), but the HP PA doesn't consider\n\
2875	PLUS to be commutative inside a MEM@. @var{outer_code} is the rtx code\n\
2876	of the enclosing rtl, if known, otherwise it is UNKNOWN.",
2877	bool, (const_rtx x, int outer_code),
2878	hook_bool_const_rtx_commutative_p)
2879
2880	/* True if ADDR is an address-expression whose effect depends
2881	on the mode of the memory reference it is used in. */
2882	DEFHOOK
2883	(mode_dependent_address_p,
2884	"This hook returns @code{true} if memory address @var{addr} in address\n\
2885	space @var{addrspace} can have\n\
2886	different meanings depending on the machine mode of the memory\n\
2887	reference it is used for or if the address is valid for some modes\n\
2888	but not others.\n\
2889	\n\
2890	Autoincrement and autodecrement addresses typically have mode-dependent\n\
2891	effects because the amount of the increment or decrement is the size\n\
2892	of the operand being addressed. Some machines have other mode-dependent\n\
2893	addresses. Many RISC machines have no mode-dependent addresses.\n\
2894	\n\
2895	You may assume that @var{addr} is a valid address for the machine.\n\
2896	\n\
2897	The default version of this hook returns @code{false}.",
2898	bool, (const_rtx addr, addr_space_t addrspace),
2899	default_mode_dependent_address_p)
2900
2901	/* Given an invalid address X for a given machine mode, try machine-specific
2902	ways to make it legitimate. Return X or an invalid address on failure. */
2903	DEFHOOK
2904	(legitimize_address,
2905	"This hook is given an invalid memory address @var{x} for an\n\
2906	operand of mode @var{mode} and should try to return a valid memory\n\
2907	address.\n\
2908	\n\
2909	@findex break_out_memory_refs\n\
2910	@var{x} will always be the result of a call to @code{break_out_memory_refs},\n\
2911	and @var{oldx} will be the operand that was given to that function to produce\n\
2912	@var{x}.\n\
2913	\n\
2914	The code of the hook should not alter the substructure of\n\
2915	@var{x}. If it transforms @var{x} into a more legitimate form, it\n\
2916	should return the new @var{x}.\n\
2917	\n\
2918	It is not necessary for this hook to come up with a legitimate address,\n\
2919	with the exception of native TLS addresses (@pxref{Emulated TLS}).\n\
2920	The compiler has standard ways of doing so in all cases. In fact, if\n\
2921	the target supports only emulated TLS, it\n\
2922	is safe to omit this hook or make it return @var{x} if it cannot find\n\
2923	a valid way to legitimize the address. But often a machine-dependent\n\
2924	strategy can generate better code.",
2925	rtx, (rtx x, rtx oldx, machine_mode mode),
2926	default_legitimize_address)
2927
2928	/* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS. */
2929	DEFHOOK
2930	(delegitimize_address,
2931	"This hook is used to undo the possibly obfuscating effects of the\n\
2932	@code{LEGITIMIZE_ADDRESS} and @code{LEGITIMIZE_RELOAD_ADDRESS} target\n\
2933	macros. Some backend implementations of these macros wrap symbol\n\
2934	references inside an @code{UNSPEC} rtx to represent PIC or similar\n\
2935	addressing modes. This target hook allows GCC's optimizers to understand\n\
2936	the semantics of these opaque @code{UNSPEC}s by converting them back\n\
2937	into their original form.",
2938	rtx, (rtx x),
2939	delegitimize_mem_from_attrs)
2940
2941	/* Given an RTX, return true if it is not ok to emit it into debug info
2942	section. */
2943	DEFHOOK
2944	(const_not_ok_for_debug_p,
2945	"This hook should return true if @var{x} should not be emitted into\n\
2946	debug sections.",
2947	bool, (rtx x),
2948	default_const_not_ok_for_debug_p)
2949
2950	/* Given an address RTX, say whether it is valid. */
2951	DEFHOOK
2952	(legitimate_address_p,
2953	"A function that returns whether @var{x} (an RTX) is a legitimate memory\n\
2954	address on the target machine for a memory operand of mode @var{mode}.\n\
2955	If @var{ch} is not @code{ERROR_MARK}, it can be called from middle-end to\n\
2956	determine if it is valid to use @var{x} as a memory operand for RTX insn\n\
2957	which is generated for the given code_helper @var{ch}. For example,\n\
2958	assuming the given @var{ch} is IFN_LEN_LOAD, on some target its underlying\n\
2959	hardware instructions support fewer addressing modes than what are for the\n\
2960	normal vector load and store, then with this @var{ch} target can know the\n\
2961	actual use context and return more exact result.\n\
2962	\n\
2963	Legitimate addresses are defined in two variants: a strict variant and a\n\
2964	non-strict one. The @var{strict} parameter chooses which variant is\n\
2965	desired by the caller.\n\
2966	\n\
2967	The strict variant is used in the reload pass. It must be defined so\n\
2968	that any pseudo-register that has not been allocated a hard register is\n\
2969	considered a memory reference. This is because in contexts where some\n\
2970	kind of register is required, a pseudo-register with no hard register\n\
2971	must be rejected. For non-hard registers, the strict variant should look\n\
2972	up the @code{reg_renumber} array; it should then proceed using the hard\n\
2973	register number in the array, or treat the pseudo as a memory reference\n\
2974	if the array holds @code{-1}.\n\
2975	\n\
2976	The non-strict variant is used in other passes. It must be defined to\n\
2977	accept all pseudo-registers in every context where some kind of\n\
2978	register is required.\n\
2979	\n\
2980	Normally, constant addresses which are the sum of a @code{symbol_ref}\n\
2981	and an integer are stored inside a @code{const} RTX to mark them as\n\
2982	constant. Therefore, there is no need to recognize such sums\n\
2983	specifically as legitimate addresses. Normally you would simply\n\
2984	recognize any @code{const} as legitimate.\n\
2985	\n\
2986	Usually @code{PRINT_OPERAND_ADDRESS} is not prepared to handle constant\n\
2987	sums that are not marked with @code{const}. It assumes that a naked\n\
2988	@code{plus} indicates indexing. If so, then you @emph{must} reject such\n\
2989	naked constant sums as illegitimate addresses, so that none of them will\n\
2990	be given to @code{PRINT_OPERAND_ADDRESS}.\n\
2991	\n\
2992	@cindex @code{TARGET_ENCODE_SECTION_INFO} and address validation\n\
2993	On some machines, whether a symbolic address is legitimate depends on\n\
2994	the section that the address refers to. On these machines, define the\n\
2995	target hook @code{TARGET_ENCODE_SECTION_INFO} to store the information\n\
2996	into the @code{symbol_ref}, and then check for it here. When you see a\n\
2997	@code{const}, you will have to look inside it to find the\n\
2998	@code{symbol_ref} in order to determine the section. @xref{Assembler\n\
2999	Format}.\n\
3000	\n\
3001	@cindex @code{GO_IF_LEGITIMATE_ADDRESS}\n\
3002	Some ports are still using a deprecated legacy substitute for\n\
3003	this hook, the @code{GO_IF_LEGITIMATE_ADDRESS} macro. This macro\n\
3004	has this syntax:\n\
3005	\n\
3006	@example\n\
3007	#define GO_IF_LEGITIMATE_ADDRESS (@var{mode}, @var{x}, @var{label})\n\
3008	@end example\n\
3009	\n\
3010	@noindent\n\
3011	and should @code{goto @var{label}} if the address @var{x} is a valid\n\
3012	address on the target machine for a memory operand of mode @var{mode}.\n\
3013	\n\
3014	@findex REG_OK_STRICT\n\
3015	Compiler source files that want to use the strict variant of this\n\
3016	macro define the macro @code{REG_OK_STRICT}. You should use an\n\
3017	@code{#ifdef REG_OK_STRICT} conditional to define the strict variant in\n\
3018	that case and the non-strict variant otherwise.\n\
3019	\n\
3020	Using the hook is usually simpler because it limits the number of\n\
3021	files that are recompiled when changes are made.",
3022	bool, (machine_mode mode, rtx x, bool strict, code_helper ch),
3023	default_legitimate_address_p)
3024
3025	/* True if the given constant can be put into an object_block. */
3026	DEFHOOK
3027	(use_blocks_for_constant_p,
3028	"This hook should return true if pool entries for constant @var{x} can\n\
3029	be placed in an @code{object_block} structure. @var{mode} is the mode\n\
3030	of @var{x}.\n\
3031	\n\
3032	The default version returns false for all constants.",
3033	bool, (machine_mode mode, const_rtx x),
3034	hook_bool_mode_const_rtx_false)
3035
3036	/* True if the given decl can be put into an object_block. */
3037	DEFHOOK
3038	(use_blocks_for_decl_p,
3039	"This hook should return true if pool entries for @var{decl} should\n\
3040	be placed in an @code{object_block} structure.\n\
3041	\n\
3042	The default version returns true for all decls.",
3043	bool, (const_tree decl),
3044	hook_bool_const_tree_true)
3045
3046	/* The minimum and maximum byte offsets for anchored addresses. */
3047	DEFHOOKPOD
3048	(min_anchor_offset,
3049	"The minimum offset that should be applied to a section anchor.\n\
3050	On most targets, it should be the smallest offset that can be\n\
3051	applied to a base register while still giving a legitimate address\n\
3052	for every mode. The default value is 0.",
3053	HOST_WIDE_INT, 0)
3054
3055	DEFHOOKPOD
3056	(max_anchor_offset,
3057	"Like @code{TARGET_MIN_ANCHOR_OFFSET}, but the maximum (inclusive)\n\
3058	offset that should be applied to section anchors. The default\n\
3059	value is 0.",
3060	HOST_WIDE_INT, 0)
3061
3062	/* True if section anchors can be used to access the given symbol. */
3063	DEFHOOK
3064	(use_anchors_for_symbol_p,
3065	"Return true if GCC should attempt to use anchors to access @code{SYMBOL_REF}\n\
3066	@var{x}. You can assume @samp{SYMBOL_REF_HAS_BLOCK_INFO_P (@var{x})} and\n\
3067	@samp{!SYMBOL_REF_ANCHOR_P (@var{x})}.\n\
3068	\n\
3069	The default version is correct for most targets, but you might need to\n\
3070	intercept this hook to handle things like target-specific attributes\n\
3071	or target-specific sections.",
3072	bool, (const_rtx x),
3073	default_use_anchors_for_symbol_p)
3074
3075	/* True if target supports indirect functions. */
3076	DEFHOOK
3077	(has_ifunc_p,
3078	"It returns true if the target supports GNU indirect functions.\n\
3079	The support includes the assembler, linker and dynamic linker.\n\
3080	The default value of this hook is based on target's libc.",
3081	bool, (void),
3082	default_has_ifunc_p)
3083
3084	/* True if it is OK to reference indirect function resolvers locally. */
3085	DEFHOOK
3086	(ifunc_ref_local_ok,
3087	"Return true if it is OK to reference indirect function resolvers\n\
3088	locally. The default is to return false.",
3089	bool, (void),
3090	hook_bool_void_false)
3091
3092	/* True if it is OK to do sibling call optimization for the specified
3093	call expression EXP. DECL will be the called function, or NULL if
3094	this is an indirect call. */
3095	DEFHOOK
3096	(function_ok_for_sibcall,
3097	"True if it is OK to do sibling call optimization for the specified\n\
3098	call expression @var{exp}. @var{decl} will be the called function,\n\
3099	or @code{NULL} if this is an indirect call.\n\
3100	\n\
3101	It is not uncommon for limitations of calling conventions to prevent\n\
3102	tail calls to functions outside the current unit of translation, or\n\
3103	during PIC compilation. The hook is used to enforce these restrictions,\n\
3104	as the @code{sibcall} md pattern cannot fail, or fall over to a\n\
3105	``normal'' call. The criteria for successful sibling call optimization\n\
3106	may vary greatly between different architectures.",
3107	bool, (tree decl, tree exp),
3108	hook_bool_tree_tree_false)
3109
3110	/* Establish appropriate back-end context for processing the function
3111	FNDECL. The argument might be NULL to indicate processing at top
3112	level, outside of any function scope. */
3113	DEFHOOK
3114	(set_current_function,
3115	"The compiler invokes this hook whenever it changes its current function\n\
3116	context (@code{cfun}). You can define this function if\n\
3117	the back end needs to perform any initialization or reset actions on a\n\
3118	per-function basis. For example, it may be used to implement function\n\
3119	attributes that affect register usage or code generation patterns.\n\
3120	The argument @var{decl} is the declaration for the new function context,\n\
3121	and may be null to indicate that the compiler has left a function context\n\
3122	and is returning to processing at the top level.\n\
3123	The default hook function does nothing.\n\
3124	\n\
3125	GCC sets @code{cfun} to a dummy function context during initialization of\n\
3126	some parts of the back end. The hook function is not invoked in this\n\
3127	situation; you need not worry about the hook being invoked recursively,\n\
3128	or when the back end is in a partially-initialized state.\n\
3129	@code{cfun} might be @code{NULL} to indicate processing at top level,\n\
3130	outside of any function scope.",
3131	void, (tree decl), hook_void_tree)
3132
3133	/* True if EXP should be placed in a "small data" section. */
3134	DEFHOOK
3135	(in_small_data_p,
3136	"Returns true if @var{exp} should be placed into a ``small data'' section.\n\
3137	The default version of this hook always returns false.",
3138	bool, (const_tree exp),
3139	hook_bool_const_tree_false)
3140
3141	/* True if EXP names an object for which name resolution must resolve
3142	to the current executable or shared library. */
3143	DEFHOOK
3144	(binds_local_p,
3145	"Returns true if @var{exp} names an object for which name resolution\n\
3146	rules must resolve to the current ``module'' (dynamic shared library\n\
3147	or executable image).\n\
3148	\n\
3149	The default version of this hook implements the name resolution rules\n\
3150	for ELF, which has a looser model of global name binding than other\n\
3151	currently supported object file formats.",
3152	bool, (const_tree exp),
3153	default_binds_local_p)
3154
3155	/* Check if profiling code is before or after prologue. */
3156	DEFHOOK
3157	(profile_before_prologue,
3158	"It returns true if target wants profile code emitted before prologue.\n\n\
3159	The default version of this hook use the target macro\n\
3160	@code{PROFILE_BEFORE_PROLOGUE}.",
3161	bool, (void),
3162	default_profile_before_prologue)
3163
3164	/* Return true if a leaf function should stay leaf even with profiling
3165	enabled. */
3166	DEFHOOK
3167	(keep_leaf_when_profiled,
3168	"This target hook returns true if the target wants the leaf flag for\n\
3169	the current function to stay true even if it calls mcount. This might\n\
3170	make sense for targets using the leaf flag only to determine whether a\n\
3171	stack frame needs to be generated or not and for which the call to\n\
3172	mcount is generated before the function prologue.",
3173	bool, (void),
3174	default_keep_leaf_when_profiled)
3175
3176	/* Modify and return the identifier of a DECL's external name,
3177	originally identified by ID, as required by the target,
3178	(eg, append @nn to windows32 stdcall function names).
3179	The default is to return ID without modification. */
3180	DEFHOOK
3181	(mangle_decl_assembler_name,
3182	"Define this hook if you need to postprocess the assembler name generated\n\
3183	by target-independent code. The @var{id} provided to this hook will be\n\
3184	the computed name (e.g., the macro @code{DECL_NAME} of the @var{decl} in C,\n\
3185	or the mangled name of the @var{decl} in C++). The return value of the\n\
3186	hook is an @code{IDENTIFIER_NODE} for the appropriate mangled name on\n\
3187	your target system. The default implementation of this hook just\n\
3188	returns the @var{id} provided.",
3189	tree, (tree decl, tree id),
3190	default_mangle_decl_assembler_name)
3191
3192	/* Do something target-specific to record properties of the DECL into
3193	the associated SYMBOL_REF. */
3194	DEFHOOK
3195	(encode_section_info,
3196	"Define this hook if references to a symbol or a constant must be\n\
3197	treated differently depending on something about the variable or\n\
3198	function named by the symbol (such as what section it is in).\n\
3199	\n\
3200	The hook is executed immediately after rtl has been created for\n\
3201	@var{decl}, which may be a variable or function declaration or\n\
3202	an entry in the constant pool. In either case, @var{rtl} is the\n\
3203	rtl in question. Do @emph{not} use @code{DECL_RTL (@var{decl})}\n\
3204	in this hook; that field may not have been initialized yet.\n\
3205	\n\
3206	In the case of a constant, it is safe to assume that the rtl is\n\
3207	a @code{mem} whose address is a @code{symbol_ref}. Most decls\n\
3208	will also have this form, but that is not guaranteed. Global\n\
3209	register variables, for instance, will have a @code{reg} for their\n\
3210	rtl. (Normally the right thing to do with such unusual rtl is\n\
3211	leave it alone.)\n\
3212	\n\
3213	The @var{new_decl_p} argument will be true if this is the first time\n\
3214	that @code{TARGET_ENCODE_SECTION_INFO} has been invoked on this decl. It will\n\
3215	be false for subsequent invocations, which will happen for duplicate\n\
3216	declarations. Whether or not anything must be done for the duplicate\n\
3217	declaration depends on whether the hook examines @code{DECL_ATTRIBUTES}.\n\
3218	@var{new_decl_p} is always true when the hook is called for a constant.\n\
3219	\n\
3220	@cindex @code{SYMBOL_REF_FLAG}, in @code{TARGET_ENCODE_SECTION_INFO}\n\
3221	The usual thing for this hook to do is to record flags in the\n\
3222	@code{symbol_ref}, using @code{SYMBOL_REF_FLAG} or @code{SYMBOL_REF_FLAGS}.\n\
3223	Historically, the name string was modified if it was necessary to\n\
3224	encode more than one bit of information, but this practice is now\n\
3225	discouraged; use @code{SYMBOL_REF_FLAGS}.\n\
3226	\n\
3227	The default definition of this hook, @code{default_encode_section_info}\n\
3228	in @file{varasm.cc}, sets a number of commonly-useful bits in\n\
3229	@code{SYMBOL_REF_FLAGS}. Check whether the default does what you need\n\
3230	before overriding it.",
3231	void, (tree decl, rtx rtl, int new_decl_p),
3232	default_encode_section_info)
3233
3234	/* Undo the effects of encode_section_info on the symbol string. */
3235	DEFHOOK
3236	(strip_name_encoding,
3237	"Decode @var{name} and return the real name part, sans\n\
3238	the characters that @code{TARGET_ENCODE_SECTION_INFO}\n\
3239	may have added.",
3240	const char *, (const char *name),
3241	default_strip_name_encoding)
3242
3243	/* If shift optabs for MODE are known to always truncate the shift count,
3244	return the mask that they apply. Return 0 otherwise. */
3245	DEFHOOK
3246	(shift_truncation_mask,
3247	"This function describes how the standard shift patterns for @var{mode}\n\
3248	deal with shifts by negative amounts or by more than the width of the mode.\n\
3249	@xref{shift patterns}.\n\
3250	\n\
3251	On many machines, the shift patterns will apply a mask @var{m} to the\n\
3252	shift count, meaning that a fixed-width shift of @var{x} by @var{y} is\n\
3253	equivalent to an arbitrary-width shift of @var{x} by @var{y & m}. If\n\
3254	this is true for mode @var{mode}, the function should return @var{m},\n\
3255	otherwise it should return 0. A return value of 0 indicates that no\n\
3256	particular behavior is guaranteed.\n\
3257	\n\
3258	Note that, unlike @code{SHIFT_COUNT_TRUNCATED}, this function does\n\
3259	@emph{not} apply to general shift rtxes; it applies only to instructions\n\
3260	that are generated by the named shift patterns.\n\
3261	\n\
3262	The default implementation of this function returns\n\
3263	@code{GET_MODE_BITSIZE (@var{mode}) - 1} if @code{SHIFT_COUNT_TRUNCATED}\n\
3264	and 0 otherwise. This definition is always safe, but if\n\
3265	@code{SHIFT_COUNT_TRUNCATED} is false, and some shift patterns\n\
3266	nevertheless truncate the shift count, you may get better code\n\
3267	by overriding it.",
3268	unsigned HOST_WIDE_INT, (machine_mode mode),
3269	default_shift_truncation_mask)
3270
3271	/* Return the number of divisions in the given MODE that should be present,
3272	so that it is profitable to turn the division into a multiplication by
3273	the reciprocal. */
3274	DEFHOOK
3275	(min_divisions_for_recip_mul,
3276	"When @option{-ffast-math} is in effect, GCC tries to optimize\n\
3277	divisions by the same divisor, by turning them into multiplications by\n\
3278	the reciprocal. This target hook specifies the minimum number of divisions\n\
3279	that should be there for GCC to perform the optimization for a variable\n\
3280	of mode @var{mode}. The default implementation returns 3 if the machine\n\
3281	has an instruction for the division, and 2 if it does not.",
3282	unsigned int, (machine_mode mode),
3283	default_min_divisions_for_recip_mul)
3284
3285	DEFHOOK
3286	(truly_noop_truncation,
3287	"This hook returns true if it is safe to ``convert'' a value of\n\
3288	@var{inprec} bits to one of @var{outprec} bits (where @var{outprec} is\n\
3289	smaller than @var{inprec}) by merely operating on it as if it had only\n\
3290	@var{outprec} bits. The default returns true unconditionally, which\n\
3291	is correct for most machines. When @code{TARGET_TRULY_NOOP_TRUNCATION}\n\
3292	returns false, the machine description should provide a @code{trunc}\n\
3293	optab to specify the RTL that performs the required truncation.\n\
3294	\n\
3295	If @code{TARGET_MODES_TIEABLE_P} returns false for a pair of modes,\n\
3296	suboptimal code can result if this hook returns true for the corresponding\n\
3297	mode sizes. Making this hook return false in such cases may improve things.",
3298	bool, (poly_uint64 outprec, poly_uint64 inprec),
3299	hook_bool_puint64_puint64_true)
3300
3301	/* If the representation of integral MODE is such that values are
3302	always sign-extended to a wider mode MODE_REP then return
3303	SIGN_EXTEND. Return UNKNOWN otherwise. */
3304	/* Note that the return type ought to be RTX_CODE, but that's not
3305	necessarily defined at this point. */
3306	DEFHOOK
3307	(mode_rep_extended,
3308	"The representation of an integral mode can be such that the values\n\
3309	are always extended to a wider integral mode. Return\n\
3310	@code{SIGN_EXTEND} if values of @var{mode} are represented in\n\
3311	sign-extended form to @var{rep_mode}. Return @code{UNKNOWN}\n\
3312	otherwise. (Currently, none of the targets use zero-extended\n\
3313	representation this way so unlike @code{LOAD_EXTEND_OP},\n\
3314	@code{TARGET_MODE_REP_EXTENDED} is expected to return either\n\
3315	@code{SIGN_EXTEND} or @code{UNKNOWN}. Also no target extends\n\
3316	@var{mode} to @var{rep_mode} so that @var{rep_mode} is not the next\n\
3317	widest integral mode and currently we take advantage of this fact.)\n\
3318	\n\
3319	Similarly to @code{LOAD_EXTEND_OP} you may return a non-@code{UNKNOWN}\n\
3320	value even if the extension is not performed on certain hard registers\n\
3321	as long as for the @code{REGNO_REG_CLASS} of these hard registers\n\
3322	@code{TARGET_CAN_CHANGE_MODE_CLASS} returns false.\n\
3323	\n\
3324	Note that @code{TARGET_MODE_REP_EXTENDED} and @code{LOAD_EXTEND_OP}\n\
3325	describe two related properties. If you define\n\
3326	@code{TARGET_MODE_REP_EXTENDED (mode, word_mode)} you probably also want\n\
3327	to define @code{LOAD_EXTEND_OP (mode)} to return the same type of\n\
3328	extension.\n\
3329	\n\
3330	In order to enforce the representation of @code{mode},\n\
3331	@code{TARGET_TRULY_NOOP_TRUNCATION} should return false when truncating to\n\
3332	@code{mode}.",
3333	int, (scalar_int_mode mode, scalar_int_mode rep_mode),
3334	default_mode_rep_extended)
3335
3336	DEFHOOK
3337	(setjmp_preserves_nonvolatile_regs_p,
3338	"On some targets, it is assumed that the compiler will spill all pseudos\n\
3339	that are live across a call to @code{setjmp}, while other targets treat\n\
3340	@code{setjmp} calls as normal function calls.\n\
3341	\n\
3342	This hook returns false if @code{setjmp} calls do not preserve all\n\
3343	non-volatile registers so that gcc that must spill all pseudos that are\n\
3344	live across @code{setjmp} calls. Define this to return true if the\n\
3345	target does not need to spill all pseudos live across @code{setjmp} calls.\n\
3346	The default implementation conservatively assumes all pseudos must be\n\
3347	spilled across @code{setjmp} calls.",
3348	bool, (void),
3349	hook_bool_void_false)
3350
3351	/* True if MODE is valid for a pointer in __attribute__((mode("MODE"))). */
3352	DEFHOOK
3353	(valid_pointer_mode,
3354	"Define this to return nonzero if the port can handle pointers\n\
3355	with machine mode @var{mode}. The default version of this\n\
3356	hook returns true for both @code{ptr_mode} and @code{Pmode}.",
3357	bool, (scalar_int_mode mode),
3358	default_valid_pointer_mode)
3359
3360	/* Disambiguate with errno. */
3361	DEFHOOK
3362	(ref_may_alias_errno,
3363	"Define this to return nonzero if the memory reference @var{ref}\n\
3364	may alias with the system C library errno location. The default\n\
3365	version of this hook assumes the system C library errno location\n\
3366	is either a declaration of type int or accessed by dereferencing\n\
3367	a pointer to int.",
3368	bool, (ao_ref *ref),
3369	default_ref_may_alias_errno)
3370
3371	DEFHOOK
3372	(mode_can_transfer_bits,
3373	"Define this to return false if the mode @var{mode} cannot be used\n\
3374	for memory copying of @code{GET_MODE_SIZE (mode)} units. This might be\n\
3375	because a register class allowed for @var{mode} has registers that do\n\
3376	not transparently transfer every bit pattern or because the load or\n\
3377	store patterns available for @var{mode} have this issue.\n\
3378	\n\
3379	The default is to assume modes with the same precision as size are fine\n\
3380	to be used.",
3381	bool, (machine_mode mode),
3382	NULL)
3383
3384	DEFHOOK
3385	(redzone_clobber,
3386	"Define this to return some RTL for the @code{redzone} @code{asm} clobber\n\
3387	if target has a red zone and wants to support the @code{redzone} clobber\n\
3388	or return NULL if the clobber should be ignored.\n\
3389	\n\
3390	The default is to ignore the @code{redzone} clobber.",
3391	rtx, (),
3392	NULL)
3393
3394	/* Support for named address spaces. */
3395	#undef HOOK_PREFIX
3396	#define HOOK_PREFIX "TARGET_ADDR_SPACE_"
3397	HOOK_VECTOR (TARGET_ADDR_SPACE_HOOKS, addr_space)
3398
3399	/* MODE to use for a pointer into another address space. */
3400	DEFHOOK
3401	(pointer_mode,
3402	"Define this to return the machine mode to use for pointers to\n\
3403	@var{address_space} if the target supports named address spaces.\n\
3404	The default version of this hook returns @code{ptr_mode}.",
3405	scalar_int_mode, (addr_space_t address_space),
3406	default_addr_space_pointer_mode)
3407
3408	/* MODE to use for an address in another address space. */
3409	DEFHOOK
3410	(address_mode,
3411	"Define this to return the machine mode to use for addresses in\n\
3412	@var{address_space} if the target supports named address spaces.\n\
3413	The default version of this hook returns @code{Pmode}.",
3414	scalar_int_mode, (addr_space_t address_space),
3415	default_addr_space_address_mode)
3416
3417	/* True if MODE is valid for a pointer in __attribute__((mode("MODE")))
3418	in another address space. */
3419	DEFHOOK
3420	(valid_pointer_mode,
3421	"Define this to return nonzero if the port can handle pointers\n\
3422	with machine mode @var{mode} to address space @var{as}. This target\n\
3423	hook is the same as the @code{TARGET_VALID_POINTER_MODE} target hook,\n\
3424	except that it includes explicit named address space support. The default\n\
3425	version of this hook returns true for the modes returned by either the\n\
3426	@code{TARGET_ADDR_SPACE_POINTER_MODE} or @code{TARGET_ADDR_SPACE_ADDRESS_MODE}\n\
3427	target hooks for the given address space.",
3428	bool, (scalar_int_mode mode, addr_space_t as),
3429	default_addr_space_valid_pointer_mode)
3430
3431	/* True if an address is a valid memory address to a given named address
3432	space for a given mode. */
3433	DEFHOOK
3434	(legitimate_address_p,
3435	"Define this to return true if @var{exp} is a valid address for mode\n\
3436	@var{mode} in the named address space @var{as} with the use context\n\
3437	@var{ch}. The @var{strict} parameter says whether strict addressing\n\
3438	is in effect after reload has finished. The @var{ch} indicates what\n\
3439	context @var{exp} will be used for. This target hook is the same as the\n\
3440	@code{TARGET_LEGITIMATE_ADDRESS_P} target hook, except that it includes\n\
3441	explicit named address space support.",
3442	bool, (machine_mode mode, rtx exp, bool strict, addr_space_t as, code_helper ch),
3443	default_addr_space_legitimate_address_p)
3444
3445	/* Return an updated address to convert an invalid pointer to a named
3446	address space to a valid one. If NULL_RTX is returned use machine
3447	independent methods to make the address valid. */
3448	DEFHOOK
3449	(legitimize_address,
3450	"Define this to modify an invalid address @var{x} to be a valid address\n\
3451	with mode @var{mode} in the named address space @var{as}. This target\n\
3452	hook is the same as the @code{TARGET_LEGITIMIZE_ADDRESS} target hook,\n\
3453	except that it includes explicit named address space support.",
3454	rtx, (rtx x, rtx oldx, machine_mode mode, addr_space_t as),
3455	default_addr_space_legitimize_address)
3456
3457	/* True if one named address space is a subset of another named address. */
3458	DEFHOOK
3459	(subset_p,
3460	"Define this to return whether the @var{subset} named address space is\n\
3461	contained within the @var{superset} named address space. Pointers to\n\
3462	a named address space that is a subset of another named address space\n\
3463	will be converted automatically without a cast if used together in\n\
3464	arithmetic operations. Pointers to a superset address space can be\n\
3465	converted to pointers to a subset address space via explicit casts.",
3466	bool, (addr_space_t subset, addr_space_t superset),
3467	default_addr_space_subset_p)
3468
3469	/* True if 0 is a valid address in the address space, or false if
3470	0 is a NULL in the address space. */
3471	DEFHOOK
3472	(zero_address_valid,
3473	"Define this to modify the default handling of address 0 for the\n\
3474	address space. Return true if 0 should be considered a valid address.",
3475	bool, (addr_space_t as),
3476	default_addr_space_zero_address_valid)
3477
3478	/* Function to convert an rtl expression from one address space to another. */
3479	DEFHOOK
3480	(convert,
3481	"Define this to convert the pointer expression represented by the RTL\n\
3482	@var{op} with type @var{from_type} that points to a named address\n\
3483	space to a new pointer expression with type @var{to_type} that points\n\
3484	to a different named address space. When this hook it called, it is\n\
3485	guaranteed that one of the two address spaces is a subset of the other,\n\
3486	as determined by the @code{TARGET_ADDR_SPACE_SUBSET_P} target hook.",
3487	rtx, (rtx op, tree from_type, tree to_type),
3488	default_addr_space_convert)
3489
3490	/* Function to encode an address space into dwarf. */
3491	DEFHOOK
3492	(debug,
3493	"Define this to define how the address space is encoded in dwarf.\n\
3494	The result is the value to be used with @code{DW_AT_address_class}.",
3495	int, (addr_space_t as),
3496	default_addr_space_debug)
3497
3498	/* Function to emit custom diagnostic if an address space is used. */
3499	DEFHOOK
3500	(diagnose_usage,
3501	"Define this hook if the availability of an address space depends on\n\
3502	command line options and some diagnostics should be printed when the\n\
3503	address space is used. This hook is called during parsing and allows\n\
3504	to emit a better diagnostic compared to the case where the address space\n\
3505	was not registered with @code{c_register_addr_space}. @var{as} is\n\
3506	the address space as registered with @code{c_register_addr_space}.\n\
3507	@var{loc} is the location of the address space qualifier token.\n\
3508	The default implementation does nothing.",
3509	void, (addr_space_t as, location_t loc),
3510	default_addr_space_diagnose_usage)
3511
3512	HOOK_VECTOR_END (addr_space)
3513
3514	#undef HOOK_PREFIX
3515	#define HOOK_PREFIX "TARGET_"
3516
3517	DEFHOOK
3518	(lower_local_decl_alignment,
3519	"Define this hook to lower alignment of local, parm or result\n\
3520	decl @samp{(@var{decl})}.",
3521	void, (tree decl),
3522	hook_void_tree)
3523
3524	DEFHOOK
3525	(static_rtx_alignment,
3526	"This hook returns the preferred alignment in bits for a\n\
3527	statically-allocated rtx, such as a constant pool entry. @var{mode}\n\
3528	is the mode of the rtx. The default implementation returns\n\
3529	@samp{GET_MODE_ALIGNMENT (@var{mode})}.",
3530	HOST_WIDE_INT, (machine_mode mode),
3531	default_static_rtx_alignment)
3532
3533	DEFHOOK
3534	(constant_alignment,
3535	"This hook returns the alignment in bits of a constant that is being\n\
3536	placed in memory. @var{constant} is the constant and @var{basic_align}\n\
3537	is the alignment that the object would ordinarily have.\n\
3538	\n\
3539	The default definition just returns @var{basic_align}.\n\
3540	\n\
3541	The typical use of this hook is to increase alignment for string\n\
3542	constants to be word aligned so that @code{strcpy} calls that copy\n\
3543	constants can be done inline. The function\n\
3544	@code{constant_alignment_word_strings} provides such a definition.",
3545	HOST_WIDE_INT, (const_tree constant, HOST_WIDE_INT basic_align),
3546	default_constant_alignment)
3547
3548	DEFHOOK
3549	(translate_mode_attribute,
3550	"Define this hook if during mode attribute processing, the port should\n\
3551	translate machine_mode @var{mode} to another mode. For example, rs6000's\n\
3552	@code{KFmode}, when it is the same as @code{TFmode}.\n\
3553	\n\
3554	The default version of the hook returns that mode that was passed in.",
3555	machine_mode, (machine_mode mode),
3556	default_translate_mode_attribute)
3557
3558	/* True if MODE is valid for the target. By "valid", we mean able to
3559	be manipulated in non-trivial ways. In particular, this means all
3560	the arithmetic is supported. */
3561	DEFHOOK
3562	(scalar_mode_supported_p,
3563	"Define this to return nonzero if the port is prepared to handle\n\
3564	insns involving scalar mode @var{mode}. For a scalar mode to be\n\
3565	considered supported, all the basic arithmetic and comparisons\n\
3566	must work.\n\
3567	\n\
3568	The default version of this hook returns true for any mode\n\
3569	required to handle the basic C types (as defined by the port).\n\
3570	Included here are the double-word arithmetic supported by the\n\
3571	code in @file{optabs.cc}.",
3572	bool, (scalar_mode mode),
3573	default_scalar_mode_supported_p)
3574
3575	/* Similarly for vector modes. "Supported" here is less strict. At
3576	least some operations are supported; need to check optabs or builtins
3577	for further details. */
3578	DEFHOOK
3579	(vector_mode_supported_p,
3580	"Define this to return nonzero if the current target is prepared to handle\n\
3581	insns involving vector mode @var{mode}. At the very least, it\n\
3582	must have move patterns for this mode.",
3583	bool, (machine_mode mode),
3584	hook_bool_mode_false)
3585
3586	DEFHOOK
3587	(vector_mode_supported_any_target_p,
3588	"Define this to return nonzero if the port is prepared to handle\n\
3589	insns involving vector mode @var{mode} in any target configuration.\n\
3590	Returning @var{true} means that the mode can be used as the @samp{TYPE_MODE}\n\
3591	for vector types.\n\
3592	\n\
3593	The default version of this hook returns true. The final mode assigned to\n\
3594	@samp{TYPE_MODE} will also be checked against\n\
3595	@code{TARGET_VECTOR_MODE_SUPPORTED_P} to take target configuration into\n\
3596	account.",
3597	bool, (machine_mode mode),
3598	hook_bool_mode_true)
3599
3600	DEFHOOK
3601	(compatible_vector_types_p,
3602	"Return true if there is no target-specific reason for treating\n\
3603	vector types @var{type1} and @var{type2} as distinct types. The caller\n\
3604	has already checked for target-independent reasons, meaning that the\n\
3605	types are known to have the same mode, to have the same number of elements,\n\
3606	and to have what the caller considers to be compatible element types.\n\
3607	\n\
3608	The main reason for defining this hook is to reject pairs of types\n\
3609	that are handled differently by the target's calling convention.\n\
3610	For example, when a new @var{N}-bit vector architecture is added\n\
3611	to a target, the target may want to handle normal @var{N}-bit\n\
3612	@code{VECTOR_TYPE} arguments and return values in the same way as\n\
3613	before, to maintain backwards compatibility. However, it may also\n\
3614	provide new, architecture-specific @code{VECTOR_TYPE}s that are passed\n\
3615	and returned in a more efficient way. It is then important to maintain\n\
3616	a distinction between the ``normal'' @code{VECTOR_TYPE}s and the new\n\
3617	architecture-specific ones.\n\
3618	\n\
3619	The default implementation returns true, which is correct for most targets.",
3620	bool, (const_tree type1, const_tree type2),
3621	hook_bool_const_tree_const_tree_true)
3622
3623	DEFHOOK
3624	(vector_alignment,
3625	"This hook can be used to define the alignment for a vector of type\n\
3626	@var{type}, in order to comply with a platform ABI. The default is to\n\
3627	require natural alignment for vector types. The alignment returned by\n\
3628	this hook must be a power-of-two multiple of the default alignment of\n\
3629	the vector element type.",
3630	HOST_WIDE_INT, (const_tree type),
3631	default_vector_alignment)
3632
3633	DEFHOOK
3634	(array_mode,
3635	"Return the mode that GCC should use for an array that has\n\
3636	@var{nelems} elements, with each element having mode @var{mode}.\n\
3637	Return no mode if the target has no special requirements. In the\n\
3638	latter case, GCC looks for an integer mode of the appropriate size\n\
3639	if available and uses BLKmode otherwise. Usually the search for the\n\
3640	integer mode is limited to @code{MAX_FIXED_MODE_SIZE}, but the\n\
3641	@code{TARGET_ARRAY_MODE_SUPPORTED_P} hook allows a larger mode to be\n\
3642	used in specific cases.\n\
3643	\n\
3644	The main use of this hook is to specify that an array of vectors should\n\
3645	also have a vector mode. The default implementation returns no mode.",
3646	opt_machine_mode, (machine_mode mode, unsigned HOST_WIDE_INT nelems),
3647	hook_optmode_mode_uhwi_none)
3648
3649	/* True if we should try to use a scalar mode to represent an array,
3650	overriding the usual MAX_FIXED_MODE limit. */
3651	DEFHOOK
3652	(array_mode_supported_p,
3653	"Return true if GCC should try to use a scalar mode to store an array\n\
3654	of @var{nelems} elements, given that each element has mode @var{mode}.\n\
3655	Returning true here overrides the usual @code{MAX_FIXED_MODE} limit\n\
3656	and allows GCC to use any defined integer mode.\n\
3657	\n\
3658	One use of this hook is to support vector load and store operations\n\
3659	that operate on several homogeneous vectors. For example, ARM NEON\n\
3660	has operations like:\n\
3661	\n\
3662	@smallexample\n\
3663	int8x8x3_t vld3_s8 (const int8_t *)\n\
3664	@end smallexample\n\
3665	\n\
3666	where the return type is defined as:\n\
3667	\n\
3668	@smallexample\n\
3669	typedef struct int8x8x3_t\n\
3670	@{\n\
3671	int8x8_t val[3];\n\
3672	@} int8x8x3_t;\n\
3673	@end smallexample\n\
3674	\n\
3675	If this hook allows @code{val} to have a scalar mode, then\n\
3676	@code{int8x8x3_t} can have the same mode. GCC can then store\n\
3677	@code{int8x8x3_t}s in registers rather than forcing them onto the stack.",
3678	bool, (machine_mode mode, unsigned HOST_WIDE_INT nelems),
3679	hook_bool_mode_uhwi_false)
3680
3681	DEFHOOK
3682	(libgcc_floating_mode_supported_p,
3683	"Define this to return nonzero if libgcc provides support for the \n\
3684	floating-point mode @var{mode}, which is known to pass \n\
3685	@code{TARGET_SCALAR_MODE_SUPPORTED_P}. The default version of this \n\
3686	hook returns true for all of @code{SFmode}, @code{DFmode}, \n\
3687	@code{XFmode} and @code{TFmode}, if such modes exist.",
3688	bool, (scalar_float_mode mode),
3689	default_libgcc_floating_mode_supported_p)
3690
3691	DEFHOOK
3692	(floatn_mode,
3693	"Define this to return the machine mode to use for the type \n\
3694	@code{_Float@var{n}}, if @var{extended} is false, or the type \n\
3695	@code{_Float@var{n}x}, if @var{extended} is true. If such a type is not\n\
3696	supported, return @code{opt_scalar_float_mode ()}. The default version of\n\
3697	this hook returns @code{SFmode} for @code{_Float32}, @code{DFmode} for\n\
3698	@code{_Float64} and @code{_Float32x} and @code{TFmode} for \n\
3699	@code{_Float128}, if those modes exist and satisfy the requirements for \n\
3700	those types and pass @code{TARGET_SCALAR_MODE_SUPPORTED_P} and \n\
3701	@code{TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P}; for @code{_Float64x}, it \n\
3702	returns the first of @code{XFmode} and @code{TFmode} that exists and \n\
3703	satisfies the same requirements; for other types, it returns \n\
3704	@code{opt_scalar_float_mode ()}. The hook is only called for values\n\
3705	of @var{n} and @var{extended} that are valid according to\n\
3706	ISO/IEC TS 18661-3:2015; that is, @var{n} is one of 32, 64, 128, or,\n\
3707	if @var{extended} is false, 16 or greater than 128 and a multiple of 32.",
3708	opt_scalar_float_mode, (int n, bool extended),
3709	default_floatn_mode)
3710
3711	DEFHOOK
3712	(floatn_builtin_p,
3713	"Define this to return true if the @code{_Float@var{n}} and\n\
3714	@code{_Float@var{n}x} built-in functions should implicitly enable the\n\
3715	built-in function without the @code{__builtin_} prefix in addition to the\n\
3716	normal built-in function with the @code{__builtin_} prefix. The default is\n\
3717	to only enable built-in functions without the @code{__builtin_} prefix for\n\
3718	the GNU C langauge. In strict ANSI/ISO mode, the built-in function without\n\
3719	the @code{__builtin_} prefix is not enabled. The argument @code{FUNC} is the\n\
3720	@code{enum built_in_function} id of the function to be enabled.",
3721	bool, (int func),
3722	default_floatn_builtin_p)
3723
3724	/* Compute cost of moving data from a register of class FROM to one of
3725	TO, using MODE. */
3726	DEFHOOK
3727	(register_move_cost,
3728	"This target hook should return the cost of moving data of mode @var{mode}\n\
3729	from a register in class @var{from} to one in class @var{to}. The classes\n\
3730	are expressed using the enumeration values such as @code{GENERAL_REGS}.\n\
3731	A value of 2 is the default; other values are interpreted relative to\n\
3732	that.\n\
3733	\n\
3734	It is not required that the cost always equal 2 when @var{from} is the\n\
3735	same as @var{to}; on some machines it is expensive to move between\n\
3736	registers if they are not general registers.\n\
3737	\n\
3738	If reload sees an insn consisting of a single @code{set} between two\n\
3739	hard registers, and if @code{TARGET_REGISTER_MOVE_COST} applied to their\n\
3740	classes returns a value of 2, reload does not check to ensure that the\n\
3741	constraints of the insn are met. Setting a cost of other than 2 will\n\
3742	allow reload to verify that the constraints are met. You should do this\n\
3743	if the @samp{mov@var{m}} pattern's constraints do not allow such copying.\n\
3744	\n\
3745	The default version of this function returns 2.",
3746	int, (machine_mode mode, reg_class_t from, reg_class_t to),
3747	default_register_move_cost)
3748
3749	/* Compute cost of moving registers to/from memory. */
3750	/* ??? Documenting the argument types for this hook requires a GFDL
3751	license grant. Also, the documentation uses a different name for RCLASS. */
3752	DEFHOOK
3753	(memory_move_cost,
3754	"This target hook should return the cost of moving data of mode @var{mode}\n\
3755	between a register of class @var{rclass} and memory; @var{in} is @code{false}\n\
3756	if the value is to be written to memory, @code{true} if it is to be read in.\n\
3757	This cost is relative to those in @code{TARGET_REGISTER_MOVE_COST}.\n\
3758	If moving between registers and memory is more expensive than between two\n\
3759	registers, you should add this target hook to express the relative cost.\n\
3760	\n\
3761	If you do not add this target hook, GCC uses a default cost of 4 plus\n\
3762	the cost of copying via a secondary reload register, if one is\n\
3763	needed. If your machine requires a secondary reload register to copy\n\
3764	between memory and a register of @var{rclass} but the reload mechanism is\n\
3765	more complex than copying via an intermediate, use this target hook to\n\
3766	reflect the actual cost of the move.\n\
3767	\n\
3768	GCC defines the function @code{memory_move_secondary_cost} if\n\
3769	secondary reloads are needed. It computes the costs due to copying via\n\
3770	a secondary register. If your machine copies from memory using a\n\
3771	secondary register in the conventional way but the default base value of\n\
3772	4 is not correct for your machine, use this target hook to add some other\n\
3773	value to the result of that function. The arguments to that function\n\
3774	are the same as to this target hook.",
3775	int, (machine_mode mode, reg_class_t rclass, bool in),
3776	default_memory_move_cost)
3777
3778	DEFHOOK
3779	(callee_save_cost,
3780	"Return the one-off cost of saving or restoring callee-saved registers\n\
3781	(also known as call-preserved registers or non-volatile registers).\n\
3782	The parameters are as follows:\n\
3783	\n\
3784	@itemize\n\
3785	@item\n\
3786	@var{cost_type} is @samp{spill_cost_type::SAVE} for saving a register\n\
3787	and @samp{spill_cost_type::RESTORE} for restoring a register.\n\
3788	\n\
3789	@item\n\
3790	@var{hard_regno} and @var{mode} represent the whole register that\n\
3791	the register allocator is considering using; of these,\n\
3792	@var{nregs} registers are fully or partially callee-saved.\n\
3793	\n\
3794	@item\n\
3795	@var{mem_cost} is the normal cost for storing (for saves)\n\
3796	or loading (for restores) the @var{nregs} registers.\n\
3797	\n\
3798	@item\n\
3799	@var{allocated_callee_regs} is the set of callee-saved registers\n\
3800	that are already in use.\n\
3801	\n\
3802	@item\n\
3803	@var{existing_spills_p} is true if the register allocator has\n\
3804	already decided to spill registers to memory.\n\
3805	@end itemize\n\
3806	\n\
3807	If @var{existing_spills_p} is false, the cost of a save should account\n\
3808	for frame allocations in a way that is consistent with\n\
3809	@code{TARGET_FRAME_ALLOCATION_COST}'s handling of allocations for spills.\n\
3810	Similarly, the cost of a restore should then account for frame deallocations\n\
3811	in a way that is consistent with @code{TARGET_FRAME_ALLOCATION_COST}'s\n\
3812	handling of deallocations.\n\
3813	\n\
3814	Note that this hook should not attempt to apply a frequency scale\n\
3815	to the cost: it is the caller's responsibility to do that where\n\
3816	appropriate.\n\
3817	\n\
3818	The default implementation returns @var{mem_cost}, plus the allocation\n\
3819	or deallocation cost returned by @code{TARGET_FRAME_ALLOCATION_COST},\n\
3820	where appropriate.",
3821	int, (spill_cost_type cost_type, unsigned int hard_regno,
3822	machine_mode mode, unsigned int nregs, int mem_cost,
3823	const HARD_REG_SET &allocated_callee_regs, bool existing_spills_p),
3824	default_callee_save_cost)
3825
3826	DEFHOOK
3827	(frame_allocation_cost,
3828	"Return the cost of allocating or deallocating a frame for the sake of\n\
3829	a spill; @var{cost_type} chooses between allocation and deallocation.\n\
3830	The term ``spill'' here includes both forcing a pseudo register to memory\n\
3831	and using caller-saved registers for pseudo registers that are live across\n\
3832	a call.\n\
3833	\n\
3834	This hook is only called if the register allocator has not so far\n\
3835	decided to spill. The allocator may have decided to use callee-saved\n\
3836	registers; if so, @var{allocated_callee_regs} is the set of callee-saved\n\
3837	registers that the allocator has used. There might also be other reasons\n\
3838	why a stack frame is already needed; for example, @samp{get_frame_size ()}\n\
3839	might be nonzero, or the target might already require a frame for\n\
3840	target-specific reasons.\n\
3841	\n\
3842	When the register allocator uses this hook to cost spills, it also uses\n\
3843	@code{TARGET_CALLEE_SAVE_COST} to cost new callee-saved registers, passing\n\
3844	@samp{false} as the @var{existing_spills_p} argument. The intention is to\n\
3845	allow the target to apply an apples-for-apples comparison between the\n\
3846	cost of using callee-saved registers and using spills in cases where the\n\
3847	allocator has not yet committed to using both strategies.\n\
3848	\n\
3849	The default implementation returns 0.",
3850	int, (frame_cost_type cost_type, const HARD_REG_SET &allocated_callee_regs),
3851	default_frame_allocation_cost)
3852
3853	DEFHOOK
3854	(use_by_pieces_infrastructure_p,
3855	"GCC will attempt several strategies when asked to copy between\n\
3856	two areas of memory, or to set, clear or store to memory, for example\n\
3857	when copying a @code{struct}. The @code{by_pieces} infrastructure\n\
3858	implements such memory operations as a sequence of load, store or move\n\
3859	insns. Alternate strategies are to expand the\n\
3860	@code{cpymem} or @code{setmem} optabs, to emit a library call, or to emit\n\
3861	unit-by-unit, loop-based operations.\n\
3862	\n\
3863	This target hook should return true if, for a memory operation with a\n\
3864	given @var{size} and @var{alignment}, using the @code{by_pieces}\n\
3865	infrastructure is expected to result in better code generation.\n\
3866	Both @var{size} and @var{alignment} are measured in terms of storage\n\
3867	units.\n\
3868	\n\
3869	The parameter @var{op} is one of: @code{CLEAR_BY_PIECES},\n\
3870	@code{MOVE_BY_PIECES}, @code{SET_BY_PIECES}, @code{STORE_BY_PIECES} or\n\
3871	@code{COMPARE_BY_PIECES}. These describe the type of memory operation\n\
3872	under consideration.\n\
3873	\n\
3874	The parameter @var{speed_p} is true if the code is currently being\n\
3875	optimized for speed rather than size.\n\
3876	\n\
3877	Returning true for higher values of @var{size} can improve code generation\n\
3878	for speed if the target does not provide an implementation of the\n\
3879	@code{cpymem} or @code{setmem} standard names, if the @code{cpymem} or\n\
3880	@code{setmem} implementation would be more expensive than a sequence of\n\
3881	insns, or if the overhead of a library call would dominate that of\n\
3882	the body of the memory operation.\n\
3883	\n\
3884	Returning true for higher values of @code{size} may also cause an increase\n\
3885	in code size, for example where the number of insns emitted to perform a\n\
3886	move would be greater than that of a library call.",
3887	bool, (unsigned HOST_WIDE_INT size, unsigned int alignment,
3888	enum by_pieces_operation op, bool speed_p),
3889	default_use_by_pieces_infrastructure_p)
3890
3891	DEFHOOK
3892	(overlap_op_by_pieces_p,
3893	"This target hook should return true if when the @code{by_pieces}\n\
3894	infrastructure is used, an offset adjusted unaligned memory operation\n\
3895	in the smallest integer mode for the last piece operation of a memory\n\
3896	region can be generated to avoid doing more than one smaller operations.",
3897	bool, (void),
3898	hook_bool_void_false)
3899
3900	DEFHOOK
3901	(compare_by_pieces_branch_ratio,
3902	"When expanding a block comparison in MODE, gcc can try to reduce the\n\
3903	number of branches at the expense of more memory operations. This hook\n\
3904	allows the target to override the default choice. It should return the\n\
3905	factor by which branches should be reduced over the plain expansion with\n\
3906	one comparison per @var{mode}-sized piece. A port can also prevent a\n\
3907	particular mode from being used for block comparisons by returning a\n\
3908	negative number from this hook.",
3909	int, (machine_mode mode),
3910	default_compare_by_pieces_branch_ratio)
3911
3912	DEFHOOK
3913	(slow_unaligned_access,
3914	"This hook returns true if memory accesses described by the\n\
3915	@var{mode} and @var{alignment} parameters have a cost many times greater\n\
3916	than aligned accesses, for example if they are emulated in a trap handler.\n\
3917	This hook is invoked only for unaligned accesses, i.e.@: when\n\
3918	@code{@var{alignment} < GET_MODE_ALIGNMENT (@var{mode})}.\n\
3919	\n\
3920	When this hook returns true, the compiler will act as if\n\
3921	@code{STRICT_ALIGNMENT} were true when generating code for block\n\
3922	moves. This can cause significantly more instructions to be produced.\n\
3923	Therefore, do not make this hook return true if unaligned accesses only\n\
3924	add a cycle or two to the time for a memory access.\n\
3925	\n\
3926	The hook must return true whenever @code{STRICT_ALIGNMENT} is true.\n\
3927	The default implementation returns @code{STRICT_ALIGNMENT}.",
3928	bool, (machine_mode mode, unsigned int align),
3929	default_slow_unaligned_access)
3930
3931	DEFHOOK
3932	(optab_supported_p,
3933	"Return true if the optimizers should use optab @var{op} with\n\
3934	modes @var{mode1} and @var{mode2} for optimization type @var{opt_type}.\n\
3935	The optab is known to have an associated @file{.md} instruction\n\
3936	whose C condition is true. @var{mode2} is only meaningful for conversion\n\
3937	optabs; for direct optabs it is a copy of @var{mode1}.\n\
3938	\n\
3939	For example, when called with @var{op} equal to @code{rint_optab} and\n\
3940	@var{mode1} equal to @code{DFmode}, the hook should say whether the\n\
3941	optimizers should use optab @code{rintdf2}.\n\
3942	\n\
3943	The default hook returns true for all inputs.",
3944	bool, (int op, machine_mode mode1, machine_mode mode2,
3945	optimization_type opt_type),
3946	default_optab_supported_p)
3947
3948	/* True for MODE if the target expects that registers in this mode will
3949	be allocated to registers in a small register class. The compiler is
3950	allowed to use registers explicitly used in the rtl as spill registers
3951	but it should prevent extending the lifetime of these registers. */
3952	DEFHOOK
3953	(small_register_classes_for_mode_p,
3954	"Define this to return nonzero for machine modes for which the port has\n\
3955	small register classes. If this target hook returns nonzero for a given\n\
3956	@var{mode}, the compiler will try to minimize the lifetime of registers\n\
3957	in @var{mode}. The hook may be called with @code{VOIDmode} as argument.\n\
3958	In this case, the hook is expected to return nonzero if it returns nonzero\n\
3959	for any mode.\n\
3960	\n\
3961	On some machines, it is risky to let hard registers live across arbitrary\n\
3962	insns. Typically, these machines have instructions that require values\n\
3963	to be in specific registers (like an accumulator), and reload will fail\n\
3964	if the required hard register is used for another purpose across such an\n\
3965	insn.\n\
3966	\n\
3967	Passes before reload do not know which hard registers will be used\n\
3968	in an instruction, but the machine modes of the registers set or used in\n\
3969	the instruction are already known. And for some machines, register\n\
3970	classes are small for, say, integer registers but not for floating point\n\
3971	registers. For example, the AMD x86-64 architecture requires specific\n\
3972	registers for the legacy x86 integer instructions, but there are many\n\
3973	SSE registers for floating point operations. On such targets, a good\n\
3974	strategy may be to return nonzero from this hook for @code{INTEGRAL_MODE_P}\n\
3975	machine modes but zero for the SSE register classes.\n\
3976	\n\
3977	The default version of this hook returns false for any mode. It is always\n\
3978	safe to redefine this hook to return with a nonzero value. But if you\n\
3979	unnecessarily define it, you will reduce the amount of optimizations\n\
3980	that can be performed in some cases. If you do not define this hook\n\
3981	to return a nonzero value when it is required, the compiler will run out\n\
3982	of spill registers and print a fatal error message.",
3983	bool, (machine_mode mode),
3984	hook_bool_mode_false)
3985
3986	/* Register number for a flags register. Only needs to be defined if the
3987	target is constrainted to use post-reload comparison elimination. */
3988	DEFHOOKPOD
3989	(flags_regnum,
3990	"If the target has a dedicated flags register, and it needs to use the\n\
3991	post-reload comparison elimination pass, or the delay slot filler pass,\n\
3992	then this value should be set appropriately.",
3993	unsigned int, INVALID_REGNUM)
3994
3995	/* Compute a (partial) cost for rtx X. Return true if the complete
3996	cost has been computed, and false if subexpressions should be
3997	scanned. In either case, *TOTAL contains the cost result. */
3998	/* Note that OUTER_CODE ought to be RTX_CODE, but that's
3999	not necessarily defined at this point. */
4000	DEFHOOK
4001	(rtx_costs,
4002	"This target hook describes the relative costs of RTL expressions.\n\
4003	\n\
4004	The cost may depend on the precise form of the expression, which is\n\
4005	available for examination in @var{x}, and the fact that @var{x} appears\n\
4006	as operand @var{opno} of an expression with rtx code @var{outer_code}.\n\
4007	That is, the hook can assume that there is some rtx @var{y} such\n\
4008	that @samp{GET_CODE (@var{y}) == @var{outer_code}} and such that\n\
4009	either (a) @samp{XEXP (@var{y}, @var{opno}) == @var{x}} or\n\
4010	(b) @samp{XVEC (@var{y}, @var{opno})} contains @var{x}.\n\
4011	\n\
4012	@var{mode} is @var{x}'s machine mode, or for cases like @code{const_int} that\n\
4013	do not have a mode, the mode in which @var{x} is used.\n\
4014	\n\
4015	In implementing this hook, you can use the construct\n\
4016	@code{COSTS_N_INSNS (@var{n})} to specify a cost equal to @var{n} fast\n\
4017	instructions.\n\
4018	\n\
4019	On entry to the hook, @code{*@var{total}} contains a default estimate\n\
4020	for the cost of the expression. The hook should modify this value as\n\
4021	necessary. Traditionally, the default costs are @code{COSTS_N_INSNS (5)}\n\
4022	for multiplications, @code{COSTS_N_INSNS (7)} for division and modulus\n\
4023	operations, and @code{COSTS_N_INSNS (1)} for all other operations.\n\
4024	\n\
4025	When optimizing for code size, i.e.@: when @code{speed} is\n\
4026	false, this target hook should be used to estimate the relative\n\
4027	size cost of an expression, again relative to @code{COSTS_N_INSNS}.\n\
4028	\n\
4029	The hook returns true when all subexpressions of @var{x} have been\n\
4030	processed, and false when @code{rtx_cost} should recurse.",
4031	bool, (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed),
4032	hook_bool_rtx_mode_int_int_intp_bool_false)
4033
4034	/* Compute the cost of X, used as an address. Never called with
4035	invalid addresses. */
4036	DEFHOOK
4037	(address_cost,
4038	"This hook computes the cost of an addressing mode that contains\n\
4039	@var{address}. If not defined, the cost is computed from\n\
4040	the @var{address} expression and the @code{TARGET_RTX_COST} hook.\n\
4041	\n\
4042	For most CISC machines, the default cost is a good approximation of the\n\
4043	true cost of the addressing mode. However, on RISC machines, all\n\
4044	instructions normally have the same length and execution time. Hence\n\
4045	all addresses will have equal costs.\n\
4046	\n\
4047	In cases where more than one form of an address is known, the form with\n\
4048	the lowest cost will be used. If multiple forms have the same, lowest,\n\
4049	cost, the one that is the most complex will be used.\n\
4050	\n\
4051	For example, suppose an address that is equal to the sum of a register\n\
4052	and a constant is used twice in the same basic block. When this macro\n\
4053	is not defined, the address will be computed in a register and memory\n\
4054	references will be indirect through that register. On machines where\n\
4055	the cost of the addressing mode containing the sum is no higher than\n\
4056	that of a simple indirect reference, this will produce an additional\n\
4057	instruction and possibly require an additional register. Proper\n\
4058	specification of this macro eliminates this overhead for such machines.\n\
4059	\n\
4060	This hook is never called with an invalid address.\n\
4061	\n\
4062	On machines where an address involving more than one register is as\n\
4063	cheap as an address computation involving only one register, defining\n\
4064	@code{TARGET_ADDRESS_COST} to reflect this can cause two registers to\n\
4065	be live over a region of code where only one would have been if\n\
4066	@code{TARGET_ADDRESS_COST} were not defined in that manner. This effect\n\
4067	should be considered in the definition of this macro. Equivalent costs\n\
4068	should probably only be given to addresses with different numbers of\n\
4069	registers on machines with lots of registers.",
4070	int, (rtx address, machine_mode mode, addr_space_t as, bool speed),
4071	default_address_cost)
4072
4073	/* Compute a cost for INSN. */
4074	DEFHOOK
4075	(insn_cost,
4076	"This target hook describes the relative costs of RTL instructions.\n\
4077	\n\
4078	In implementing this hook, you can use the construct\n\
4079	@code{COSTS_N_INSNS (@var{n})} to specify a cost equal to @var{n} fast\n\
4080	instructions.\n\
4081	\n\
4082	When optimizing for code size, i.e.@: when @code{speed} is\n\
4083	false, this target hook should be used to estimate the relative\n\
4084	size cost of an expression, again relative to @code{COSTS_N_INSNS}.",
4085	int, (rtx_insn *insn, bool speed), NULL)
4086
4087	/* Give a cost, in RTX Costs units, for an edge. Like BRANCH_COST, but with
4088	well defined units. */
4089	DEFHOOK
4090	(max_noce_ifcvt_seq_cost,
4091	"This hook returns a value in the same units as @code{TARGET_RTX_COSTS},\n\
4092	giving the maximum acceptable cost for a sequence generated by the RTL\n\
4093	if-conversion pass when conditional execution is not available.\n\
4094	The RTL if-conversion pass attempts to convert conditional operations\n\
4095	that would require a branch to a series of unconditional operations and\n\
4096	@code{mov@var{mode}cc} insns. This hook returns the maximum cost of the\n\
4097	unconditional instructions and the @code{mov@var{mode}cc} insns.\n\
4098	RTL if-conversion is cancelled if the cost of the converted sequence\n\
4099	is greater than the value returned by this hook.\n\
4100	\n\
4101	@code{e} is the edge between the basic block containing the conditional\n\
4102	branch to the basic block which would be executed if the condition\n\
4103	were true.\n\
4104	\n\
4105	The default implementation of this hook uses the\n\
4106	@code{max-rtl-if-conversion-[un]predictable} parameters if they are set,\n\
4107	and uses a multiple of @code{BRANCH_COST} otherwise.",
4108	unsigned int, (edge e),
4109	default_max_noce_ifcvt_seq_cost)
4110
4111	/* Return true if the given instruction sequence is a good candidate
4112	as a replacement for the if-convertible sequence. */
4113	DEFHOOK
4114	(noce_conversion_profitable_p,
4115	"This hook returns true if the instruction sequence @code{seq} is a good\n\
4116	candidate as a replacement for the if-convertible sequence described in\n\
4117	@code{if_info}.",
4118	bool, (rtx_insn *seq, struct noce_if_info *if_info),
4119	default_noce_conversion_profitable_p)
4120
4121	/* Return true if new_addr should be preferred over the existing address used by
4122	memref in insn. */
4123	DEFHOOK
4124	(new_address_profitable_p,
4125	"Return @code{true} if it is profitable to replace the address in\n\
4126	@var{memref} with @var{new_addr}. This allows targets to prevent the\n\
4127	scheduler from undoing address optimizations. The instruction containing the\n\
4128	memref is @var{insn}. The default implementation returns @code{true}.",
4129	bool, (rtx memref, rtx_insn * insn, rtx new_addr),
4130	default_new_address_profitable_p)
4131
4132	DEFHOOK
4133	(estimated_poly_value,
4134	"Return an estimate of the runtime value of @var{val}, for use in\n\
4135	things like cost calculations or profiling frequencies. @var{kind} is used\n\
4136	to ask for the minimum, maximum, and likely estimates of the value through\n\
4137	the @code{POLY_VALUE_MIN}, @code{POLY_VALUE_MAX} and\n\
4138	@code{POLY_VALUE_LIKELY} values. The default\n\
4139	implementation returns the lowest possible value of @var{val}.",
4140	HOST_WIDE_INT, (poly_int64 val, poly_value_estimate_kind kind),
4141	default_estimated_poly_value)
4142
4143	/* Permit speculative instructions in delay slots during delayed-branch
4144	scheduling. */
4145	DEFHOOK
4146	(no_speculation_in_delay_slots_p,
4147	"This predicate controls the use of the eager delay slot filler to disallow\n\
4148	speculatively executed instructions being placed in delay slots. Targets\n\
4149	such as certain MIPS architectures possess both branches with and without\n\
4150	delay slots. As the eager delay slot filler can decrease performance,\n\
4151	disabling it is beneficial when ordinary branches are available. Use of\n\
4152	delay slot branches filled using the basic filler is often still desirable\n\
4153	as the delay slot can hide a pipeline bubble.",
4154	bool, (void),
4155	hook_bool_void_false)
4156
4157	/* Return where to allocate pseudo for a given hard register initial value. */
4158	DEFHOOK
4159	(allocate_initial_value,
4160	"\n\
4161	When the initial value of a hard register has been copied in a pseudo\n\
4162	register, it is often not necessary to actually allocate another register\n\
4163	to this pseudo register, because the original hard register or a stack slot\n\
4164	it has been saved into can be used. @code{TARGET_ALLOCATE_INITIAL_VALUE}\n\
4165	is called at the start of register allocation once for each hard register\n\
4166	that had its initial value copied by using\n\
4167	@code{get_func_hard_reg_initial_val} or @code{get_hard_reg_initial_val}.\n\
4168	Possible values are @code{NULL_RTX}, if you don't want\n\
4169	to do any special allocation, a @code{REG} rtx---that would typically be\n\
4170	the hard register itself, if it is known not to be clobbered---or a\n\
4171	@code{MEM}.\n\
4172	If you are returning a @code{MEM}, this is only a hint for the allocator;\n\
4173	it might decide to use another register anyways.\n\
4174	You may use @code{current_function_is_leaf} or \n\
4175	@code{REG_N_SETS} in the hook to determine if the hard\n\
4176	register in question will not be clobbered.\n\
4177	The default value of this hook is @code{NULL}, which disables any special\n\
4178	allocation.",
4179	rtx, (rtx hard_reg), NULL)
4180
4181	/* Return nonzero if evaluating UNSPEC X might cause a trap.
4182	FLAGS has the same meaning as in rtlanal.cc: may_trap_p_1. */
4183	DEFHOOK
4184	(unspec_may_trap_p,
4185	"This target hook returns nonzero if @var{x}, an @code{unspec} might cause\n\
4186	a trap. Targets can use this hook to enhance precision of analysis for\n\
4187	@code{unspec} operations. You may call @code{may_trap_p_1} to analyze inner\n\
4188	elements of @var{x} in which case @var{flags} should be passed along.",
4189	int, (const_rtx x, unsigned flags),
4190	default_unspec_may_trap_p)
4191
4192	/* Given a register, this hook should return a parallel of registers
4193	to represent where to find the register pieces. Define this hook
4194	if the register and its mode are represented in Dwarf in
4195	non-contiguous locations, or if the register should be
4196	represented in more than one register in Dwarf. Otherwise, this
4197	hook should return NULL_RTX. */
4198	DEFHOOK
4199	(dwarf_register_span,
4200	"Given a register, this hook should return a parallel of registers to\n\
4201	represent where to find the register pieces. Define this hook if the\n\
4202	register and its mode are represented in Dwarf in non-contiguous\n\
4203	locations, or if the register should be represented in more than one\n\
4204	register in Dwarf. Otherwise, this hook should return @code{NULL_RTX}.\n\
4205	If not defined, the default is to return @code{NULL_RTX}.",
4206	rtx, (rtx reg),
4207	hook_rtx_rtx_null)
4208
4209	/* Given a register return the mode of the corresponding DWARF frame
4210	register. */
4211	DEFHOOK
4212	(dwarf_frame_reg_mode,
4213	"Given a register, this hook should return the mode which the\n\
4214	corresponding Dwarf frame register should have. This is normally\n\
4215	used to return a smaller mode than the raw mode to prevent call\n\
4216	clobbered parts of a register altering the frame register size",
4217	machine_mode, (int regno),
4218	default_dwarf_frame_reg_mode)
4219
4220	/* Print out architecture-specific CFI directives to the assembly file. */
4221	DEFHOOK
4222	(output_cfi_directive,
4223	"This hook handles architecture-specific CFI directives and prints\n\
4224	them out to the assembly file @var{f}.\n\
4225	Return true if a architecture-specific directive was found, false\n\
4226	otherwise.",
4227	bool, (FILE * f, dw_cfi_ref cfi),
4228	hook_bool_FILEptr_dwcfiptr_false)
4229
4230	DEFHOOK
4231	(dw_cfi_oprnd1_desc,
4232	"This hook informs the caller what the architecture-specific directives\n\
4233	takes as a first operand.\n\
4234	Return true if a architecture-specific directive was found and\n\
4235	@var{oprnd_type} is set, false otherwise and @var{oprnd_type} is not\n\
4236	modified.",
4237	bool, (dwarf_call_frame_info cfi_opc, dw_cfi_oprnd_type & oprnd_type),
4238	hook_bool_dwcfi_dwcfioprndtyperef_false)
4239
4240	/* If expand_builtin_init_dwarf_reg_sizes needs to fill in table
4241	entries not corresponding directly to registers below
4242	FIRST_PSEUDO_REGISTER, this hook should generate the necessary
4243	code, given the address of the table. */
4244	DEFHOOK
4245	(init_dwarf_reg_sizes_extra,
4246	"If some registers are represented in Dwarf-2 unwind information in\n\
4247	multiple pieces, define this hook to fill in information about the\n\
4248	sizes of those pieces in the table used by the unwinder at runtime.\n\
4249	It will be called by @code{expand_builtin_init_dwarf_reg_sizes} after\n\
4250	filling in a single size corresponding to each hard register;\n\
4251	@var{address} is the address of the table.",
4252	void, (tree address),
4253	hook_void_tree)
4254
4255	/* Fetch the fixed register(s) which hold condition codes, for
4256	targets where it makes sense to look for duplicate assignments to
4257	the condition codes. This should return true if there is such a
4258	register, false otherwise. The arguments should be set to the
4259	fixed register numbers. Up to two condition code registers are
4260	supported. If there is only one for this target, the int pointed
4261	at by the second argument should be set to -1. */
4262	DEFHOOK
4263	(fixed_condition_code_regs,
4264	"On targets which use a hard\n\
4265	register rather than a pseudo-register to hold condition codes, the\n\
4266	regular CSE passes are often not able to identify cases in which the\n\
4267	hard register is set to a common value. Use this hook to enable a\n\
4268	small pass which optimizes such cases. This hook should return true\n\
4269	to enable this pass, and it should set the integers to which its\n\
4270	arguments point to the hard register numbers used for condition codes.\n\
4271	When there is only one such register, as is true on most systems, the\n\
4272	integer pointed to by @var{p2} should be set to\n\
4273	@code{INVALID_REGNUM}.\n\
4274	\n\
4275	The default version of this hook returns false.",
4276	bool, (unsigned int *p1, unsigned int *p2),
4277	hook_bool_uintp_uintp_false)
4278
4279	/* If two condition code modes are compatible, return a condition
4280	code mode which is compatible with both, such that a comparison
4281	done in the returned mode will work for both of the original
4282	modes. If the condition code modes are not compatible, return
4283	VOIDmode. */
4284	DEFHOOK
4285	(cc_modes_compatible,
4286	"On targets which use multiple condition code modes in class\n\
4287	@code{MODE_CC}, it is sometimes the case that a comparison can be\n\
4288	validly done in more than one mode. On such a system, define this\n\
4289	target hook to take two mode arguments and to return a mode in which\n\
4290	both comparisons may be validly done. If there is no such mode,\n\
4291	return @code{VOIDmode}.\n\
4292	\n\
4293	The default version of this hook checks whether the modes are the\n\
4294	same. If they are, it returns that mode. If they are different, it\n\
4295	returns @code{VOIDmode}.",
4296	machine_mode, (machine_mode m1, machine_mode m2),
4297	default_cc_modes_compatible)
4298
4299	DEFHOOK
4300	(use_late_prologue_epilogue,
4301	"Return true if the current function's prologue and epilogue should\n\
4302	be emitted late in the pass pipeline, instead of at the usual point.\n\
4303	\n\
4304	Normally, the prologue and epilogue sequences are introduced soon after\n\
4305	register allocation is complete. The advantage of this approach is that\n\
4306	it allows the prologue and epilogue instructions to be optimized and\n\
4307	scheduled with other code in the function. However, some targets\n\
4308	require the prologue and epilogue to be the first and last sequences\n\
4309	executed by the function, with no variation allowed. This hook should\n\
4310	return true on such targets.\n\
4311	\n\
4312	The default implementation returns false, which is correct for most\n\
4313	targets. The hook should only return true if there is a specific\n\
4314	target limitation that cannot be described in RTL. For example,\n\
4315	the hook might return true if the prologue and epilogue need to switch\n\
4316	between instruction sets.",
4317	bool, (),
4318	hook_bool_void_false)
4319
4320	DEFHOOK
4321	(emit_epilogue_for_sibcall,
4322	"If defined, this hook emits an epilogue sequence for sibling (tail)\n\
4323	call instruction @var{call}. Another way of providing epilogues\n\
4324	for sibling calls is to define the @code{sibcall_epilogue} instruction\n\
4325	pattern; the main advantage of this hook over the pattern is that it\n\
4326	has access to the call instruction.",
4327	void, (rtx_call_insn *call), NULL)
4328
4329	/* Do machine-dependent code transformations. Called just before
4330	delayed-branch scheduling. */
4331	DEFHOOK
4332	(machine_dependent_reorg,
4333	"If non-null, this hook performs a target-specific pass over the\n\
4334	instruction stream. The compiler will run it at all optimization levels,\n\
4335	just before the point at which it normally does delayed-branch scheduling.\n\
4336	\n\
4337	The exact purpose of the hook varies from target to target. Some use\n\
4338	it to do transformations that are necessary for correctness, such as\n\
4339	laying out in-function constant pools or avoiding hardware hazards.\n\
4340	Others use it as an opportunity to do some machine-dependent optimizations.\n\
4341	\n\
4342	You need not implement the hook if it has nothing to do. The default\n\
4343	definition is null.",
4344	void, (void), NULL)
4345
4346	/* Create the __builtin_va_list type. */
4347	DEFHOOK
4348	(build_builtin_va_list,
4349	"This hook returns a type node for @code{va_list} for the target.\n\
4350	The default version of the hook returns @code{void*}.",
4351	tree, (void),
4352	std_build_builtin_va_list)
4353
4354	/* Enumerate the va list variants. */
4355	DEFHOOK
4356	(enum_va_list_p,
4357	"This target hook is used in function @code{c_common_nodes_and_builtins}\n\
4358	to iterate through the target specific builtin types for va_list. The\n\
4359	variable @var{idx} is used as iterator. @var{pname} has to be a pointer\n\
4360	to a @code{const char *} and @var{ptree} a pointer to a @code{tree} typed\n\
4361	variable.\n\
4362	The arguments @var{pname} and @var{ptree} are used to store the result of\n\
4363	this macro and are set to the name of the va_list builtin type and its\n\
4364	internal type.\n\
4365	If the return value of this macro is zero, then there is no more element.\n\
4366	Otherwise the @var{IDX} should be increased for the next call of this\n\
4367	macro to iterate through all types.",
4368	int, (int idx, const char **pname, tree *ptree),
4369	NULL)
4370
4371	/* Get the cfun/fndecl calling abi __builtin_va_list type. */
4372	DEFHOOK
4373	(fn_abi_va_list,
4374	"This hook returns the va_list type of the calling convention specified by\n\
4375	@var{fndecl}.\n\
4376	The default version of this hook returns @code{va_list_type_node}.",
4377	tree, (tree fndecl),
4378	std_fn_abi_va_list)
4379
4380	/* Get the __builtin_va_list type dependent on input type. */
4381	DEFHOOK
4382	(canonical_va_list_type,
4383	"This hook returns the va_list type of the calling convention specified by the\n\
4384	type of @var{type}. If @var{type} is not a valid va_list type, it returns\n\
4385	@code{NULL_TREE}.",
4386	tree, (tree type),
4387	std_canonical_va_list_type)
4388
4389	/* ??? Documenting this hook requires a GFDL license grant. */
4390	DEFHOOK_UNDOC
4391	(expand_builtin_va_start,
4392	"Expand the @code{__builtin_va_start} builtin.",
4393	void, (tree valist, rtx nextarg), NULL)
4394
4395	/* Gimplifies a VA_ARG_EXPR. */
4396	DEFHOOK
4397	(gimplify_va_arg_expr,
4398	"This hook performs target-specific gimplification of\n\
4399	@code{VA_ARG_EXPR}. The first two parameters correspond to the\n\
4400	arguments to @code{va_arg}; the latter two are as in\n\
4401	@code{gimplify.cc:gimplify_expr}.",
4402	tree, (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p),
4403	std_gimplify_va_arg_expr)
4404
4405	/* Validity-checking routines for PCH files, target-specific.
4406	get_pch_validity returns a pointer to the data to be stored,
4407	and stores the size in its argument. pch_valid_p gets the same
4408	information back and returns NULL if the PCH is valid,
4409	or an error message if not. */
4410	DEFHOOK
4411	(get_pch_validity,
4412	"This hook returns a pointer to the data needed by\n\
4413	@code{TARGET_PCH_VALID_P} and sets\n\
4414	@samp{*@var{sz}} to the size of the data in bytes.",
4415	void *, (size_t *sz),
4416	default_get_pch_validity)
4417
4418	DEFHOOK
4419	(pch_valid_p,
4420	"This hook checks whether the options used to create a PCH file are\n\
4421	compatible with the current settings. It returns @code{NULL}\n\
4422	if so and a suitable error message if not. Error messages will\n\
4423	be presented to the user and must be localized using @samp{_(@var{msg})}.\n\
4424	\n\
4425	@var{data} is the data that was returned by @code{TARGET_GET_PCH_VALIDITY}\n\
4426	when the PCH file was created and @var{sz} is the size of that data in bytes.\n\
4427	It's safe to assume that the data was created by the same version of the\n\
4428	compiler, so no format checking is needed.\n\
4429	\n\
4430	The default definition of @code{default_pch_valid_p} should be\n\
4431	suitable for most targets.",
4432	const char *, (const void *data, size_t sz),
4433	default_pch_valid_p)
4434
4435	DEFHOOK
4436	(prepare_pch_save,
4437	"Called before writing out a PCH file. If the target has some\n\
4438	garbage-collected data that needs to be in a particular state on PCH loads,\n\
4439	it can use this hook to enforce that state. Very few targets need\n\
4440	to do anything here.",
4441	void, (void),
4442	hook_void_void)
4443
4444	/* If nonnull, this function checks whether a PCH file with the
4445	given set of target flags can be used. It returns NULL if so,
4446	otherwise it returns an error message. */
4447	DEFHOOK
4448	(check_pch_target_flags,
4449	"If this hook is nonnull, the default implementation of\n\
4450	@code{TARGET_PCH_VALID_P} will use it to check for compatible values\n\
4451	of @code{target_flags}. @var{pch_flags} specifies the value that\n\
4452	@code{target_flags} had when the PCH file was created. The return\n\
4453	value is the same as for @code{TARGET_PCH_VALID_P}.",
4454	const char *, (int pch_flags), NULL)
4455
4456	/* True if the compiler should give an enum type only as many
4457	bytes as it takes to represent the range of possible values of
4458	that type. */
4459	DEFHOOK
4460	(default_short_enums,
4461	"This target hook should return true if the compiler should give an\n\
4462	@code{enum} type only as many bytes as it takes to represent the range\n\
4463	of possible values of that type. It should return false if all\n\
4464	@code{enum} types should be allocated like @code{int}.\n\
4465	\n\
4466	The default is to return false.",
4467	bool, (void),
4468	hook_bool_void_false)
4469
4470	/* This target hook returns an rtx that is used to store the address
4471	of the current frame into the built-in setjmp buffer. */
4472	DEFHOOK
4473	(builtin_setjmp_frame_value,
4474	"This target hook should return an rtx that is used to store\n\
4475	the address of the current frame into the built in @code{setjmp} buffer.\n\
4476	The default value, @code{virtual_stack_vars_rtx}, is correct for most\n\
4477	machines. One reason you may need to define this target hook is if\n\
4478	@code{hard_frame_pointer_rtx} is the appropriate value on your machine.",
4479	rtx, (void),
4480	default_builtin_setjmp_frame_value)
4481
4482	/* This target hook should manipulate the outputs, inputs, constraints,
4483	and clobbers the port wishes for pre-processing the asm. */
4484	DEFHOOK
4485	(md_asm_adjust,
4486	"This target hook may add @dfn{clobbers} to @var{clobbers} and\n\
4487	@var{clobbered_regs} for any hard regs the port wishes to automatically\n\
4488	clobber for an asm. It can also add hard registers that are used by the\n\
4489	asm to @var{uses}. The @var{outputs} and @var{inputs} may be inspected\n\
4490	to avoid clobbering a register that is already used by the asm. @var{loc}\n\
4491	is the source location of the asm.\n\
4492	\n\
4493	It may modify the @var{outputs}, @var{inputs}, @var{input_modes}, and\n\
4494	@var{constraints} as necessary for other pre-processing. In this case the\n\
4495	return value is a sequence of insns to emit after the asm. Note that\n\
4496	changes to @var{inputs} must be accompanied by the corresponding changes\n\
4497	to @var{input_modes}.",
4498	rtx_insn *,
4499	(vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes,
4500	vec<const char *>& constraints, vec<rtx>& usess, vec<rtx>& clobbers,
4501	HARD_REG_SET& clobbered_regs, location_t loc),
4502	NULL)
4503
4504	/* This target hook allows the backend to specify a calling convention
4505	in the debug information. This function actually returns an
4506	enum dwarf_calling_convention, but because of forward declarations
4507	and not wanting to include dwarf2.h everywhere target.h is included
4508	the function is being declared as an int. */
4509	DEFHOOK
4510	(dwarf_calling_convention,
4511	"Define this to enable the dwarf attribute @code{DW_AT_calling_convention} to\n\
4512	be emitted for each function. Instead of an integer return the enum\n\
4513	value for the @code{DW_CC_} tag.",
4514	int, (const_tree function),
4515	hook_int_const_tree_0)
4516
4517	/* This target hook allows the backend to emit frame-related insns that
4518	contain UNSPECs or UNSPEC_VOLATILEs. The call frame debugging info
4519	engine will invoke it on insns of the form
4520	(set (reg) (unspec [...] UNSPEC_INDEX))
4521	and
4522	(set (reg) (unspec_volatile [...] UNSPECV_INDEX))
4523	to let the backend emit the call frame instructions. */
4524	DEFHOOK
4525	(dwarf_handle_frame_unspec,
4526	"This target hook allows the backend to emit frame-related insns that\n\
4527	contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging\n\
4528	info engine will invoke it on insns of the form\n\
4529	@smallexample\n\
4530	(set (reg) (unspec [@dots{}] UNSPEC_INDEX))\n\
4531	@end smallexample\n\
4532	and\n\
4533	@smallexample\n\
4534	(set (reg) (unspec_volatile [@dots{}] UNSPECV_INDEX)).\n\
4535	@end smallexample\n\
4536	to let the backend emit the call frame instructions. @var{label} is\n\
4537	the CFI label attached to the insn, @var{pattern} is the pattern of\n\
4538	the insn and @var{index} is @code{UNSPEC_INDEX} or @code{UNSPECV_INDEX}.",
4539	void, (const char *label, rtx pattern, int index), NULL)
4540
4541	DEFHOOK
4542	(dwarf_poly_indeterminate_value,
4543	"Express the value of @code{poly_int} indeterminate @var{i} as a DWARF\n\
4544	expression, with @var{i} counting from 1. Return the number of a DWARF\n\
4545	register @var{R} and set @samp{*@var{factor}} and @samp{*@var{offset}} such\n\
4546	that the value of the indeterminate is:\n\
4547	@smallexample\n\
4548	value_of(@var{R}) / @var{factor} - @var{offset}\n\
4549	@end smallexample\n\
4550	\n\
4551	A target only needs to define this hook if it sets\n\
4552	@samp{NUM_POLY_INT_COEFFS} to a value greater than 1.",
4553	unsigned int, (unsigned int i, unsigned int *factor, int *offset),
4554	default_dwarf_poly_indeterminate_value)
4555
4556	/* ??? Documenting this hook requires a GFDL license grant. */
4557	DEFHOOK_UNDOC
4558	(stdarg_optimize_hook,
4559	"Perform architecture specific checking of statements gimplified\
4560	from @code{VA_ARG_EXPR}. @var{stmt} is the statement. Returns true if\
4561	the statement doesn't need to be checked for @code{va_list} references.",
4562	bool, (struct stdarg_info *ai, const gimple *stmt), NULL)
4563
4564	/* This target hook allows the operating system to override the DECL
4565	that represents the external variable that contains the stack
4566	protection guard variable. The type of this DECL is ptr_type_node. */
4567	DEFHOOK
4568	(stack_protect_guard,
4569	"This hook returns a @code{DECL} node for the external variable to use\n\
4570	for the stack protection guard. This variable is initialized by the\n\
4571	runtime to some random value and is used to initialize the guard value\n\
4572	that is placed at the top of the local stack frame. The type of this\n\
4573	variable must be @code{ptr_type_node}.\n\
4574	\n\
4575	The default version of this hook creates a variable called\n\
4576	@samp{__stack_chk_guard}, which is normally defined in @file{libgcc2.c}.",
4577	tree, (void),
4578	default_stack_protect_guard)
4579
4580	/* This target hook allows the operating system to override the CALL_EXPR
4581	that is invoked when a check vs the guard variable fails. */
4582	DEFHOOK
4583	(stack_protect_fail,
4584	"This hook returns a @code{CALL_EXPR} that alerts the runtime that the\n\
4585	stack protect guard variable has been modified. This expression should\n\
4586	involve a call to a @code{noreturn} function.\n\
4587	\n\
4588	The default version of this hook invokes a function called\n\
4589	@samp{__stack_chk_fail}, taking no arguments. This function is\n\
4590	normally defined in @file{libgcc2.c}.",
4591	tree, (void),
4592	default_external_stack_protect_fail)
4593
4594	/* This target hook allows the operating system to disable the default stack
4595	protector runtime support. */
4596	DEFHOOK
4597	(stack_protect_runtime_enabled_p,
4598	"Returns true if the target wants GCC's default stack protect runtime support,\n\
4599	otherwise return false. The default implementation always returns true.",
4600	bool, (void),
4601	hook_bool_void_true)
4602
4603	DEFHOOK
4604	(have_strub_support_for,
4605	"Returns true if the target supports stack scrubbing for the given function\n\
4606	or type, otherwise return false. The default implementation always returns\n\
4607	true.",
4608	bool, (tree),
4609	hook_bool_tree_true)
4610
4611	DEFHOOK
4612	(have_speculation_safe_value,
4613	"This hook is used to determine the level of target support for\n\
4614	@code{__builtin_speculation_safe_value}. If called with an argument\n\
4615	of false, it returns true if the target has been modified to support\n\
4616	this builtin. If called with an argument of true, it returns true\n\
4617	if the target requires active mitigation execution might be speculative.\n\
4618	\n\
4619	The default implementation returns false if the target does not define\n\
4620	a pattern named @code{speculation_barrier}. Else it returns true\n\
4621	for the first case and whether the pattern is enabled for the current\n\
4622	compilation for the second case.\n\
4623	\n\
4624	For targets that have no processors that can execute instructions\n\
4625	speculatively an alternative implemenation of this hook is available:\n\
4626	simply redefine this hook to @code{speculation_safe_value_not_needed}\n\
4627	along with your other target hooks.",
4628	bool, (bool active), default_have_speculation_safe_value)
4629
4630	DEFHOOK
4631	(speculation_safe_value,
4632	"This target hook can be used to generate a target-specific code\n\
4633	sequence that implements the @code{__builtin_speculation_safe_value}\n\
4634	built-in function. The function must always return @var{val} in\n\
4635	@var{result} in mode @var{mode} when the cpu is not executing\n\
4636	speculatively, but must never return that when speculating until it\n\
4637	is known that the speculation will not be unwound. The hook supports\n\
4638	two primary mechanisms for implementing the requirements. The first\n\
4639	is to emit a speculation barrier which forces the processor to wait\n\
4640	until all prior speculative operations have been resolved; the second\n\
4641	is to use a target-specific mechanism that can track the speculation\n\
4642	state and to return @var{failval} if it can determine that\n\
4643	speculation must be unwound at a later time.\n\
4644	\n\
4645	The default implementation simply copies @var{val} to @var{result} and\n\
4646	emits a @code{speculation_barrier} instruction if that is defined.",
4647	rtx, (machine_mode mode, rtx result, rtx val, rtx failval),
4648	default_speculation_safe_value)
4649
4650	DEFHOOK
4651	(predict_doloop_p,
4652	"Return true if we can predict it is possible to use a low-overhead loop\n\
4653	for a particular loop. The parameter @var{loop} is a pointer to the loop.\n\
4654	This target hook is required only when the target supports low-overhead\n\
4655	loops, and will help ivopts to make some decisions.\n\
4656	The default version of this hook returns false.",
4657	bool, (class loop *loop),
4658	default_predict_doloop_p)
4659
4660	DEFHOOKPOD
4661	(have_count_reg_decr_p,
4662	"Return true if the target supports hardware count register for decrement\n\
4663	and branch.\n\
4664	The default value is false.",
4665	bool, false)
4666
4667	DEFHOOKPOD
4668	(doloop_cost_for_generic,
4669	"One IV candidate dedicated for doloop is introduced in IVOPTs, we can\n\
4670	calculate the computation cost of adopting it to any generic IV use by\n\
4671	function get_computation_cost as before. But for targets which have\n\
4672	hardware count register support for decrement and branch, it may have to\n\
4673	move IV value from hardware count register to general purpose register\n\
4674	while doloop IV candidate is used for generic IV uses. It probably takes\n\
4675	expensive penalty. This hook allows target owners to define the cost for\n\
4676	this especially for generic IV uses.\n\
4677	The default value is zero.",
4678	int64_t, 0)
4679
4680	DEFHOOKPOD
4681	(doloop_cost_for_address,
4682	"One IV candidate dedicated for doloop is introduced in IVOPTs, we can\n\
4683	calculate the computation cost of adopting it to any address IV use by\n\
4684	function get_computation_cost as before. But for targets which have\n\
4685	hardware count register support for decrement and branch, it may have to\n\
4686	move IV value from hardware count register to general purpose register\n\
4687	while doloop IV candidate is used for address IV uses. It probably takes\n\
4688	expensive penalty. This hook allows target owners to define the cost for\n\
4689	this escpecially for address IV uses.\n\
4690	The default value is zero.",
4691	int64_t, 0)
4692
4693	DEFHOOK
4694	(can_use_doloop_p,
4695	"Return true if it is possible to use low-overhead loops (@code{doloop_end}\n\
4696	and @code{doloop_begin}) for a particular loop. @var{iterations} gives the\n\
4697	exact number of iterations, or 0 if not known. @var{iterations_max} gives\n\
4698	the maximum number of iterations, or 0 if not known. @var{loop_depth} is\n\
4699	the nesting depth of the loop, with 1 for innermost loops, 2 for loops that\n\
4700	contain innermost loops, and so on. @var{entered_at_top} is true if the\n\
4701	loop is only entered from the top.\n\
4702	\n\
4703	This hook is only used if @code{doloop_end} is available. The default\n\
4704	implementation returns true. You can use @code{can_use_doloop_if_innermost}\n\
4705	if the loop must be the innermost, and if there are no other restrictions.",
4706	bool, (const widest_int &iterations, const widest_int &iterations_max,
4707	unsigned int loop_depth, bool entered_at_top),
4708	hook_bool_wint_wint_uint_bool_true)
4709
4710	/* Returns NULL if target supports the insn within a doloop block,
4711	otherwise it returns an error message. */
4712	DEFHOOK
4713	(invalid_within_doloop,
4714	"\n\
4715	Take an instruction in @var{insn} and return NULL if it is valid within a\n\
4716	low-overhead loop, otherwise return a string explaining why doloop\n\
4717	could not be applied.\n\
4718	\n\
4719	Many targets use special registers for low-overhead looping. For any\n\
4720	instruction that clobbers these this function should return a string indicating\n\
4721	the reason why the doloop could not be applied.\n\
4722	By default, the RTL loop optimizer does not use a present doloop pattern for\n\
4723	loops containing function calls or branch on table instructions.",
4724	const char *, (const rtx_insn *insn),
4725	default_invalid_within_doloop)
4726
4727	/* Returns the machine mode which the target prefers for doloop IV. */
4728	DEFHOOK
4729	(preferred_doloop_mode,
4730	"This hook takes a @var{mode} for a doloop IV, where @code{mode} is the\n\
4731	original mode for the operation. If the target prefers an alternate\n\
4732	@code{mode} for the operation, then this hook should return that mode;\n\
4733	otherwise the original @code{mode} should be returned. For example, on a\n\
4734	64-bit target, @code{DImode} might be preferred over @code{SImode}. Both the\n\
4735	original and the returned modes should be @code{MODE_INT}.",
4736	machine_mode,
4737	(machine_mode mode),
4738	default_preferred_doloop_mode)
4739
4740	/* Returns true for a legitimate combined insn. */
4741	DEFHOOK
4742	(legitimate_combined_insn,
4743	"Take an instruction in @var{insn} and return @code{false} if the instruction\n\
4744	is not appropriate as a combination of two or more instructions. The\n\
4745	default is to accept all instructions.",
4746	bool, (rtx_insn *insn),
4747	hook_bool_rtx_insn_true)
4748
4749	DEFHOOK
4750	(valid_dllimport_attribute_p,
4751	"@var{decl} is a variable or function with @code{__attribute__((dllimport))}\n\
4752	specified. Use this hook if the target needs to add extra validation\n\
4753	checks to @code{handle_dll_attribute}.",
4754	bool, (const_tree decl),
4755	hook_bool_const_tree_true)
4756
4757	/* If non-zero, align constant anchors in CSE to a multiple of this
4758	value. */
4759	DEFHOOKPOD
4760	(const_anchor,
4761	"On some architectures it can take multiple instructions to synthesize\n\
4762	a constant. If there is another constant already in a register that\n\
4763	is close enough in value then it is preferable that the new constant\n\
4764	is computed from this register using immediate addition or\n\
4765	subtraction. We accomplish this through CSE. Besides the value of\n\
4766	the constant we also add a lower and an upper constant anchor to the\n\
4767	available expressions. These are then queried when encountering new\n\
4768	constants. The anchors are computed by rounding the constant up and\n\
4769	down to a multiple of the value of @code{TARGET_CONST_ANCHOR}.\n\
4770	@code{TARGET_CONST_ANCHOR} should be the maximum positive value\n\
4771	accepted by immediate-add plus one. We currently assume that the\n\
4772	value of @code{TARGET_CONST_ANCHOR} is a power of 2. For example, on\n\
4773	MIPS, where add-immediate takes a 16-bit signed value,\n\
4774	@code{TARGET_CONST_ANCHOR} is set to @samp{0x8000}. The default value\n\
4775	is zero, which disables this optimization.",
4776	unsigned HOST_WIDE_INT, 0)
4777
4778	/* Defines, which target-dependent bits (upper 16) are used by port */
4779	DEFHOOK
4780	(memmodel_check,
4781	"Validate target specific memory model mask bits. When NULL no target specific\n\
4782	memory model bits are allowed.",
4783	unsigned HOST_WIDE_INT, (unsigned HOST_WIDE_INT val), NULL)
4784
4785	/* Defines an offset bitwise ored into shifted address to get corresponding
4786	Address Sanitizer shadow address, or -1 if Address Sanitizer is not
4787	supported by the target. */
4788	DEFHOOK
4789	(asan_shadow_offset,
4790	"Return the offset bitwise ored into shifted address to get corresponding\n\
4791	Address Sanitizer shadow memory address. NULL if Address Sanitizer is not\n\
4792	supported by the target. May return 0 if Address Sanitizer is not supported\n\
4793	or using dynamic shadow offset by a subtarget.",
4794	unsigned HOST_WIDE_INT, (void),
4795	NULL)
4796
4797	DEFHOOK
4798	(asan_dynamic_shadow_offset_p,
4799	"Return true if asan should use dynamic shadow offset.",
4800	bool, (void),
4801	hook_bool_void_false)
4802
4803	/* Functions relating to calls - argument passing, returns, etc. */
4804	/* Members of struct call have no special macro prefix. */
4805	HOOK_VECTOR (TARGET_CALLS, calls)
4806
4807	DEFHOOK
4808	(promote_function_mode,
4809	"Like @code{PROMOTE_MODE}, but it is applied to outgoing function arguments or\n\
4810	function return values. The target hook should return the new mode\n\
4811	and possibly change @code{*@var{punsignedp}} if the promotion should\n\
4812	change signedness. This function is called only for scalar @emph{or\n\
4813	pointer} types.\n\
4814	\n\
4815	@var{for_return} allows to distinguish the promotion of arguments and\n\
4816	return values. If it is @code{1}, a return value is being promoted and\n\
4817	@code{TARGET_FUNCTION_VALUE} must perform the same promotions done here.\n\
4818	If it is @code{2}, the returned mode should be that of the register in\n\
4819	which an incoming parameter is copied, or the outgoing result is computed;\n\
4820	then the hook should return the same mode as @code{promote_mode}, though\n\
4821	the signedness may be different.\n\
4822	\n\
4823	@var{type} can be NULL when promoting function arguments of libcalls.\n\
4824	\n\
4825	The default is to not promote arguments and return values. You can\n\
4826	also define the hook to @code{default_promote_function_mode_always_promote}\n\
4827	if you would like to apply the same rules given by @code{PROMOTE_MODE}.",
4828	machine_mode, (const_tree type, machine_mode mode, int *punsignedp,
4829	const_tree funtype, int for_return),
4830	default_promote_function_mode)
4831
4832	DEFHOOK
4833	(promote_prototypes,
4834	"This target hook returns @code{true} if an argument declared in a\n\
4835	prototype as an integral type smaller than @code{int} should actually be\n\
4836	passed as an @code{int}. In addition to avoiding errors in certain\n\
4837	cases of mismatch, it also makes for better code on certain machines.\n\
4838	The default is to not promote prototypes.",
4839	bool, (const_tree fntype),
4840	hook_bool_const_tree_false)
4841
4842	DEFHOOK
4843	(struct_value_rtx,
4844	"This target hook should return the location of the structure value\n\
4845	address (normally a @code{mem} or @code{reg}), or 0 if the address is\n\
4846	passed as an ``invisible'' first argument. Note that @var{fndecl} may\n\
4847	be @code{NULL}, for libcalls. You do not need to define this target\n\
4848	hook if the address is always passed as an ``invisible'' first\n\
4849	argument.\n\
4850	\n\
4851	On some architectures the place where the structure value address\n\
4852	is found by the called function is not the same place that the\n\
4853	caller put it. This can be due to register windows, or it could\n\
4854	be because the function prologue moves it to a different place.\n\
4855	@var{incoming} is @code{1} or @code{2} when the location is needed in\n\
4856	the context of the called function, and @code{0} in the context of\n\
4857	the caller.\n\
4858	\n\
4859	If @var{incoming} is nonzero and the address is to be found on the\n\
4860	stack, return a @code{mem} which refers to the frame pointer. If\n\
4861	@var{incoming} is @code{2}, the result is being used to fetch the\n\
4862	structure value address at the beginning of a function. If you need\n\
4863	to emit adjusting code, you should do it at this point.",
4864	rtx, (tree fndecl, int incoming),
4865	hook_rtx_tree_int_null)
4866
4867	DEFHOOKPOD
4868	(omit_struct_return_reg,
4869	"Normally, when a function returns a structure by memory, the address\n\
4870	is passed as an invisible pointer argument, but the compiler also\n\
4871	arranges to return the address from the function like it would a normal\n\
4872	pointer return value. Define this to true if that behavior is\n\
4873	undesirable on your target.",
4874	bool, false)
4875
4876	DEFHOOK
4877	(return_in_memory,
4878	"This target hook should return a nonzero value to say to return the\n\
4879	function value in memory, just as large structures are always returned.\n\
4880	Here @var{type} will be the data type of the value, and @var{fntype}\n\
4881	will be the type of the function doing the returning, or @code{NULL} for\n\
4882	libcalls.\n\
4883	\n\
4884	Note that values of mode @code{BLKmode} must be explicitly handled\n\
4885	by this function. Also, the option @option{-fpcc-struct-return}\n\
4886	takes effect regardless of this macro. On most systems, it is\n\
4887	possible to leave the hook undefined; this causes a default\n\
4888	definition to be used, whose value is the constant 1 for @code{BLKmode}\n\
4889	values, and 0 otherwise.\n\
4890	\n\
4891	Do not use this hook to indicate that structures and unions should always\n\
4892	be returned in memory. You should instead use @code{DEFAULT_PCC_STRUCT_RETURN}\n\
4893	to indicate this.",
4894	bool, (const_tree type, const_tree fntype),
4895	default_return_in_memory)
4896
4897	DEFHOOK
4898	(return_in_msb,
4899	"This hook should return true if values of type @var{type} are returned\n\
4900	at the most significant end of a register (in other words, if they are\n\
4901	padded at the least significant end). You can assume that @var{type}\n\
4902	is returned in a register; the caller is required to check this.\n\
4903	\n\
4904	Note that the register provided by @code{TARGET_FUNCTION_VALUE} must\n\
4905	be able to hold the complete return value. For example, if a 1-, 2-\n\
4906	or 3-byte structure is returned at the most significant end of a\n\
4907	4-byte register, @code{TARGET_FUNCTION_VALUE} should provide an\n\
4908	@code{SImode} rtx.",
4909	bool, (const_tree type),
4910	hook_bool_const_tree_false)
4911
4912	/* Return true if a parameter must be passed by reference. TYPE may
4913	be null if this is a libcall. CA may be null if this query is
4914	from __builtin_va_arg. */
4915	DEFHOOK
4916	(pass_by_reference,
4917	"This target hook should return @code{true} if argument @var{arg} at the\n\
4918	position indicated by @var{cum} should be passed by reference. This\n\
4919	predicate is queried after target independent reasons for being\n\
4920	passed by reference, such as @code{TREE_ADDRESSABLE (@var{arg}.type)}.\n\
4921	\n\
4922	If the hook returns true, a copy of that argument is made in memory and a\n\
4923	pointer to the argument is passed instead of the argument itself.\n\
4924	The pointer is passed in whatever way is appropriate for passing a pointer\n\
4925	to that type.",
4926	bool,
4927	(cumulative_args_t cum, const function_arg_info &arg),
4928	hook_bool_CUMULATIVE_ARGS_arg_info_false)
4929
4930	DEFHOOK
4931	(expand_builtin_saveregs,
4932	"If defined, this hook produces the machine-specific code for a call to\n\
4933	@code{__builtin_saveregs}. This code will be moved to the very\n\
4934	beginning of the function, before any parameter access are made. The\n\
4935	return value of this function should be an RTX that contains the value\n\
4936	to use as the return of @code{__builtin_saveregs}.",
4937	rtx, (void),
4938	default_expand_builtin_saveregs)
4939
4940	/* Returns pretend_argument_size. */
4941	DEFHOOK
4942	(setup_incoming_varargs,
4943	"This target hook offers an alternative to using\n\
4944	@code{__builtin_saveregs} and defining the hook\n\
4945	@code{TARGET_EXPAND_BUILTIN_SAVEREGS}. Use it to store the anonymous\n\
4946	register arguments into the stack so that all the arguments appear to\n\
4947	have been passed consecutively on the stack. Once this is done, you can\n\
4948	use the standard implementation of varargs that works for machines that\n\
4949	pass all their arguments on the stack.\n\
4950	\n\
4951	The argument @var{args_so_far} points to the @code{CUMULATIVE_ARGS} data\n\
4952	structure, containing the values that are obtained after processing the\n\
4953	named arguments. The argument @var{arg} describes the last of these named\n\
4954	arguments. The argument @var{arg} should not be used if the function type\n\
4955	satisfies @code{TYPE_NO_NAMED_ARGS_STDARG_P}, since in that case there are\n\
4956	no named arguments and all arguments are accessed with @code{va_arg}.\n\
4957	\n\
4958	The target hook should do two things: first, push onto the stack all the\n\
4959	argument registers @emph{not} used for the named arguments, and second,\n\
4960	store the size of the data thus pushed into the @code{int}-valued\n\
4961	variable pointed to by @var{pretend_args_size}. The value that you\n\
4962	store here will serve as additional offset for setting up the stack\n\
4963	frame.\n\
4964	\n\
4965	Because you must generate code to push the anonymous arguments at\n\
4966	compile time without knowing their data types,\n\
4967	@code{TARGET_SETUP_INCOMING_VARARGS} is only useful on machines that\n\
4968	have just a single category of argument register and use it uniformly\n\
4969	for all data types.\n\
4970	\n\
4971	If the argument @var{second_time} is nonzero, it means that the\n\
4972	arguments of the function are being analyzed for the second time. This\n\
4973	happens for an inline function, which is not actually compiled until the\n\
4974	end of the source file. The hook @code{TARGET_SETUP_INCOMING_VARARGS} should\n\
4975	not generate any instructions in this case.",
4976	void, (cumulative_args_t args_so_far, const function_arg_info &arg,
4977	int *pretend_args_size, int second_time),
4978	default_setup_incoming_varargs)
4979
4980	DEFHOOK
4981	(start_call_args,
4982	"This target hook is invoked while generating RTL for a function call,\n\
4983	after the argument values have been computed, and after stack arguments\n\
4984	have been initialized, but before register arguments have been moved into\n\
4985	their ABI-defined hard register locations. It precedes calls to the related\n\
4986	hooks @code{TARGET_CALL_ARGS} and @code{TARGET_END_CALL_ARGS}.\n\
4987	The significance of this position in the call expansion is that:\n\
4988	\n\
4989	@itemize @bullet\n\
4990	@item\n\
4991	No argument registers are live.\n\
4992	@item\n\
4993	Although a call sequence can in general involve subcalls (such as using\n\
4994	@code{memcpy} to copy large arguments), no such subcall will occur between\n\
4995	the call to this hook and the generation of the main call instruction.\n\
4996	@end itemize\n\
4997	\n\
4998	The single argument @var{complete_args} is the state of the target\n\
4999	function's cumulative argument information after the final call to\n\
5000	@code{TARGET_FUNCTION_ARG}.\n\
5001	\n\
5002	The hook can be used for things like switching processor mode, in cases\n\
5003	where different calls need different processor modes. Most ports do not\n\
5004	need to implement anything for this hook.",
5005	void, (cumulative_args_t complete_args),
5006	hook_void_CUMULATIVE_ARGS)
5007
5008	DEFHOOK
5009	(call_args,
5010	"While generating RTL for a function call, this target hook is invoked once\n\
5011	for each argument passed to the function, either a register returned by\n\
5012	@code{TARGET_FUNCTION_ARG} or a memory location. It is called just\n\
5013	before the point where argument registers are stored.\n\
5014	\n\
5015	@var{complete_args} is the state of the target function's cumulative\n\
5016	argument information after the final call to @code{TARGET_FUNCTION_ARG}.\n\
5017	@var{loc} is the location of the argument. @var{type} is the type of\n\
5018	the function being called, or @code{NULL_TREE} for libcalls.\n\
5019	\n\
5020	For functions without arguments, the hook is called once with @code{pc_rtx}\n\
5021	passed instead of an argument register.\n\
5022	\n\
5023	This functionality can be used to perform special setup of call argument\n\
5024	registers, if a target needs it. Most ports do not need to implement\n\
5025	anything for this hook.",
5026	void, (cumulative_args_t complete_args, rtx loc, tree type),
5027	hook_void_CUMULATIVE_ARGS_rtx_tree)
5028
5029	DEFHOOK
5030	(end_call_args,
5031	"This target hook is invoked while generating RTL for a function call,\n\
5032	just after the point where the return reg is copied into a pseudo. It\n\
5033	signals that all the call argument and return registers for the just\n\
5034	emitted call are now no longer in use. @var{complete_args} is the\n\
5035	state of the target function's cumulative argument information after\n\
5036	the final call to @code{TARGET_FUNCTION_ARG}.\n\
5037	\n\
5038	Most ports do not need to implement anything for this hook.",
5039	void, (cumulative_args_t complete_args),
5040	hook_void_CUMULATIVE_ARGS)
5041
5042	DEFHOOK
5043	(call_offset_return_label,
5044	"While generating call-site debug info for a CALL insn, or a SEQUENCE\n\
5045	insn starting with a CALL, this target hook is invoked to compute the\n\
5046	offset to be added to the debug label emitted after the call to obtain\n\
5047	the return address that should be recorded as the return PC.",
5048	int, (rtx_insn *call_insn),
5049	hook_int_rtx_insn_0)
5050
5051	DEFHOOK
5052	(push_argument,
5053	"This target hook returns @code{true} if push instructions will be\n\
5054	used to pass outgoing arguments. When the push instruction usage is\n\
5055	optional, @var{npush} is nonzero to indicate the number of bytes to\n\
5056	push. Otherwise, @var{npush} is zero. If the target machine does not\n\
5057	have a push instruction or push instruction should be avoided,\n\
5058	@code{false} should be returned. That directs GCC to use an alternate\n\
5059	strategy: to allocate the entire argument block and then store the\n\
5060	arguments into it. If this target hook may return @code{true},\n\
5061	@code{PUSH_ROUNDING} must be defined.",
5062	bool, (unsigned int npush),
5063	default_push_argument)
5064
5065	DEFHOOK
5066	(strict_argument_naming,
5067	"Define this hook to return @code{true} if the location where a function\n\
5068	argument is passed depends on whether or not it is a named argument.\n\
5069	\n\
5070	This hook controls how the @var{named} argument to @code{TARGET_FUNCTION_ARG}\n\
5071	is set for varargs and stdarg functions. If this hook returns\n\
5072	@code{true}, the @var{named} argument is always true for named\n\
5073	arguments, and false for unnamed arguments. If it returns @code{false},\n\
5074	but @code{TARGET_PRETEND_OUTGOING_VARARGS_NAMED} returns @code{true},\n\
5075	then all arguments are treated as named. Otherwise, all named arguments\n\
5076	except the last are treated as named.\n\
5077	\n\
5078	You need not define this hook if it always returns @code{false}.",
5079	bool, (cumulative_args_t ca),
5080	hook_bool_CUMULATIVE_ARGS_false)
5081
5082	/* Returns true if we should use
5083	targetm.calls.setup_incoming_varargs() and/or
5084	targetm.calls.strict_argument_naming(). */
5085	DEFHOOK
5086	(pretend_outgoing_varargs_named,
5087	"If you need to conditionally change ABIs so that one works with\n\
5088	@code{TARGET_SETUP_INCOMING_VARARGS}, but the other works like neither\n\
5089	@code{TARGET_SETUP_INCOMING_VARARGS} nor @code{TARGET_STRICT_ARGUMENT_NAMING} was\n\
5090	defined, then define this hook to return @code{true} if\n\
5091	@code{TARGET_SETUP_INCOMING_VARARGS} is used, @code{false} otherwise.\n\
5092	Otherwise, you should not define this hook.",
5093	bool, (cumulative_args_t ca),
5094	default_pretend_outgoing_varargs_named)
5095
5096	/* Given a complex type T, return true if a parameter of type T
5097	should be passed as two scalars. */
5098	DEFHOOK
5099	(split_complex_arg,
5100	"This hook should return true if parameter of type @var{type} are passed\n\
5101	as two scalar parameters. By default, GCC will attempt to pack complex\n\
5102	arguments into the target's word size. Some ABIs require complex arguments\n\
5103	to be split and treated as their individual components. For example, on\n\
5104	AIX64, complex floats should be passed in a pair of floating point\n\
5105	registers, even though a complex float would fit in one 64-bit floating\n\
5106	point register.\n\
5107	\n\
5108	The default value of this hook is @code{NULL}, which is treated as always\n\
5109	false.",
5110	bool, (const_tree type), NULL)
5111
5112	/* Return true if type T, mode MODE, may not be passed in registers,
5113	but must be passed on the stack. */
5114	/* ??? This predicate should be applied strictly after pass-by-reference.
5115	Need audit to verify that this is the case. */
5116	DEFHOOK
5117	(must_pass_in_stack,
5118	"This target hook should return @code{true} if we should not pass @var{arg}\n\
5119	solely in registers. The file @file{expr.h} defines a\n\
5120	definition that is usually appropriate, refer to @file{expr.h} for additional\n\
5121	documentation.",
5122	bool, (const function_arg_info &arg),
5123	must_pass_in_stack_var_size_or_pad)
5124
5125	/* Return true if type TYPE, mode MODE, which is passed by reference,
5126	should have the object copy generated by the callee rather than
5127	the caller. It is never called for TYPE requiring constructors. */
5128	DEFHOOK
5129	(callee_copies,
5130	"The function argument described by the parameters to this hook is\n\
5131	known to be passed by reference. The hook should return true if the\n\
5132	function argument should be copied by the callee instead of copied\n\
5133	by the caller.\n\
5134	\n\
5135	For any argument for which the hook returns true, if it can be\n\
5136	determined that the argument is not modified, then a copy need\n\
5137	not be generated.\n\
5138	\n\
5139	The default version of this hook always returns false.",
5140	bool,
5141	(cumulative_args_t cum, const function_arg_info &arg),
5142	hook_bool_CUMULATIVE_ARGS_arg_info_false)
5143
5144	/* Return zero for arguments passed entirely on the stack or entirely
5145	in registers. If passed in both, return the number of bytes passed
5146	in registers; the balance is therefore passed on the stack. */
5147	DEFHOOK
5148	(arg_partial_bytes,
5149	"This target hook returns the number of bytes at the beginning of an\n\
5150	argument that must be put in registers. The value must be zero for\n\
5151	arguments that are passed entirely in registers or that are entirely\n\
5152	pushed on the stack.\n\
5153	\n\
5154	On some machines, certain arguments must be passed partially in\n\
5155	registers and partially in memory. On these machines, typically the\n\
5156	first few words of arguments are passed in registers, and the rest\n\
5157	on the stack. If a multi-word argument (a @code{double} or a\n\
5158	structure) crosses that boundary, its first few words must be passed\n\
5159	in registers and the rest must be pushed. This macro tells the\n\
5160	compiler when this occurs, and how many bytes should go in registers.\n\
5161	\n\
5162	@code{TARGET_FUNCTION_ARG} for these arguments should return the first\n\
5163	register to be used by the caller for this argument; likewise\n\
5164	@code{TARGET_FUNCTION_INCOMING_ARG}, for the called function.",
5165	int, (cumulative_args_t cum, const function_arg_info &arg),
5166	hook_int_CUMULATIVE_ARGS_arg_info_0)
5167
5168	/* Update the state in CA to advance past an argument in the
5169	argument list. The values MODE, TYPE, and NAMED describe that
5170	argument. */
5171	DEFHOOK
5172	(function_arg_advance,
5173	"This hook updates the summarizer variable pointed to by @var{ca} to\n\
5174	advance past argument @var{arg} in the argument list. Once this is done,\n\
5175	the variable @var{cum} is suitable for analyzing the @emph{following}\n\
5176	argument with @code{TARGET_FUNCTION_ARG}, etc.\n\
5177	\n\
5178	This hook need not do anything if the argument in question was passed\n\
5179	on the stack. The compiler knows how to track the amount of stack space\n\
5180	used for arguments without any special help.",
5181	void,
5182	(cumulative_args_t ca, const function_arg_info &arg),
5183	default_function_arg_advance)
5184
5185	DEFHOOK
5186	(function_arg_offset,
5187	"This hook returns the number of bytes to add to the offset of an\n\
5188	argument of type @var{type} and mode @var{mode} when passed in memory.\n\
5189	This is needed for the SPU, which passes @code{char} and @code{short}\n\
5190	arguments in the preferred slot that is in the middle of the quad word\n\
5191	instead of starting at the top. The default implementation returns 0.",
5192	HOST_WIDE_INT, (machine_mode mode, const_tree type),
5193	default_function_arg_offset)
5194
5195	DEFHOOK
5196	(function_arg_padding,
5197	"This hook determines whether, and in which direction, to pad out\n\
5198	an argument of mode @var{mode} and type @var{type}. It returns\n\
5199	@code{PAD_UPWARD} to insert padding above the argument, @code{PAD_DOWNWARD}\n\
5200	to insert padding below the argument, or @code{PAD_NONE} to inhibit padding.\n\
5201	\n\
5202	The @emph{amount} of padding is not controlled by this hook, but by\n\
5203	@code{TARGET_FUNCTION_ARG_ROUND_BOUNDARY}. It is always just enough\n\
5204	to reach the next multiple of that boundary.\n\
5205	\n\
5206	This hook has a default definition that is right for most systems.\n\
5207	For little-endian machines, the default is to pad upward. For\n\
5208	big-endian machines, the default is to pad downward for an argument of\n\
5209	constant size shorter than an @code{int}, and upward otherwise.",
5210	pad_direction, (machine_mode mode, const_tree type),
5211	default_function_arg_padding)
5212
5213	/* Return zero if the argument described by the state of CA should
5214	be placed on a stack, or a hard register in which to store the
5215	argument. The values MODE, TYPE, and NAMED describe that
5216	argument. */
5217	DEFHOOK
5218	(function_arg,
5219	"Return an RTX indicating whether function argument @var{arg} is passed\n\
5220	in a register and if so, which register. Argument @var{ca} summarizes all\n\
5221	the previous arguments.\n\
5222	\n\
5223	The return value is usually either a @code{reg} RTX for the hard\n\
5224	register in which to pass the argument, or zero to pass the argument\n\
5225	on the stack.\n\
5226	\n\
5227	The value of the expression can also be a @code{parallel} RTX@. This is\n\
5228	used when an argument is passed in multiple locations. The mode of the\n\
5229	@code{parallel} should be the mode of the entire argument. The\n\
5230	@code{parallel} holds any number of @code{expr_list} pairs; each one\n\
5231	describes where part of the argument is passed. In each\n\
5232	@code{expr_list} the first operand must be a @code{reg} RTX for the hard\n\
5233	register in which to pass this part of the argument, and the mode of the\n\
5234	register RTX indicates how large this part of the argument is. The\n\
5235	second operand of the @code{expr_list} is a @code{const_int} which gives\n\
5236	the offset in bytes into the entire argument of where this part starts.\n\
5237	As a special exception the first @code{expr_list} in the @code{parallel}\n\
5238	RTX may have a first operand of zero. This indicates that the entire\n\
5239	argument is also stored on the stack.\n\
5240	\n\
5241	The last time this hook is called, it is called with @code{MODE ==\n\
5242	VOIDmode}, and its result is passed to the @code{call} or @code{call_value}\n\
5243	pattern as operands 2 and 3 respectively.\n\
5244	\n\
5245	@cindex @file{stdarg.h} and register arguments\n\
5246	The usual way to make the ISO library @file{stdarg.h} work on a\n\
5247	machine where some arguments are usually passed in registers, is to\n\
5248	cause nameless arguments to be passed on the stack instead. This is\n\
5249	done by making @code{TARGET_FUNCTION_ARG} return 0 whenever\n\
5250	@var{named} is @code{false}.\n\
5251	\n\
5252	@cindex @code{TARGET_MUST_PASS_IN_STACK}, and @code{TARGET_FUNCTION_ARG}\n\
5253	@cindex @code{REG_PARM_STACK_SPACE}, and @code{TARGET_FUNCTION_ARG}\n\
5254	You may use the hook @code{targetm.calls.must_pass_in_stack}\n\
5255	in the definition of this macro to determine if this argument is of a\n\
5256	type that must be passed in the stack. If @code{REG_PARM_STACK_SPACE}\n\
5257	is not defined and @code{TARGET_FUNCTION_ARG} returns nonzero for such an\n\
5258	argument, the compiler will abort. If @code{REG_PARM_STACK_SPACE} is\n\
5259	defined, the argument will be computed in the stack and then loaded into\n\
5260	a register.",
5261	rtx, (cumulative_args_t ca, const function_arg_info &arg),
5262	default_function_arg)
5263
5264	DEFHOOK
5265	(function_incoming_arg,
5266	"Define this hook if the caller and callee on the target have different\n\
5267	views of where arguments are passed. Also define this hook if there are\n\
5268	functions that are never directly called, but are invoked by the hardware\n\
5269	and which have nonstandard calling conventions.\n\
5270	\n\
5271	In this case @code{TARGET_FUNCTION_ARG} computes the register in\n\
5272	which the caller passes the value, and\n\
5273	@code{TARGET_FUNCTION_INCOMING_ARG} should be defined in a similar\n\
5274	fashion to tell the function being called where the arguments will\n\
5275	arrive.\n\
5276	\n\
5277	@code{TARGET_FUNCTION_INCOMING_ARG} can also return arbitrary address\n\
5278	computation using hard register, which can be forced into a register,\n\
5279	so that it can be used to pass special arguments.\n\
5280	\n\
5281	If @code{TARGET_FUNCTION_INCOMING_ARG} is not defined,\n\
5282	@code{TARGET_FUNCTION_ARG} serves both purposes.",
5283	rtx, (cumulative_args_t ca, const function_arg_info &arg),
5284	default_function_incoming_arg)
5285
5286	DEFHOOK
5287	(function_arg_boundary,
5288	"This hook returns the alignment boundary, in bits, of an argument\n\
5289	with the specified mode and type. The default hook returns\n\
5290	@code{PARM_BOUNDARY} for all arguments.",
5291	unsigned int, (machine_mode mode, const_tree type),
5292	default_function_arg_boundary)
5293
5294	DEFHOOK
5295	(function_arg_round_boundary,
5296	"Normally, the size of an argument is rounded up to @code{PARM_BOUNDARY},\n\
5297	which is the default value for this hook. You can define this hook to\n\
5298	return a different value if an argument size must be rounded to a larger\n\
5299	value.",
5300	unsigned int, (machine_mode mode, const_tree type),
5301	default_function_arg_round_boundary)
5302
5303	/* Return the diagnostic message string if function without a prototype
5304	is not allowed for this 'val' argument; NULL otherwise. */
5305	DEFHOOK
5306	(invalid_arg_for_unprototyped_fn,
5307	"If defined, this macro returns the diagnostic message when it is\n\
5308	illegal to pass argument @var{val} to function @var{funcdecl}\n\
5309	with prototype @var{typelist}.",
5310	const char *, (const_tree typelist, const_tree funcdecl, const_tree val),
5311	hook_invalid_arg_for_unprototyped_fn)
5312
5313	/* Return an rtx for the return value location of the function
5314	specified by FN_DECL_OR_TYPE with a return type of RET_TYPE. */
5315	DEFHOOK
5316	(function_value,
5317	"\n\
5318	Define this to return an RTX representing the place where a function\n\
5319	returns or receives a value of data type @var{ret_type}, a tree node\n\
5320	representing a data type. @var{fn_decl_or_type} is a tree node\n\
5321	representing @code{FUNCTION_DECL} or @code{FUNCTION_TYPE} of a\n\
5322	function being called. If @var{outgoing} is false, the hook should\n\
5323	compute the register in which the caller will see the return value.\n\
5324	Otherwise, the hook should return an RTX representing the place where\n\
5325	a function returns a value.\n\
5326	\n\
5327	On many machines, only @code{TYPE_MODE (@var{ret_type})} is relevant.\n\
5328	(Actually, on most machines, scalar values are returned in the same\n\
5329	place regardless of mode.) The value of the expression is usually a\n\
5330	@code{reg} RTX for the hard register where the return value is stored.\n\
5331	The value can also be a @code{parallel} RTX, if the return value is in\n\
5332	multiple places. See @code{TARGET_FUNCTION_ARG} for an explanation of the\n\
5333	@code{parallel} form. Note that the callee will populate every\n\
5334	location specified in the @code{parallel}, but if the first element of\n\
5335	the @code{parallel} contains the whole return value, callers will use\n\
5336	that element as the canonical location and ignore the others. The m68k\n\
5337	port uses this type of @code{parallel} to return pointers in both\n\
5338	@samp{%a0} (the canonical location) and @samp{%d0}.\n\
5339	\n\
5340	If the precise function being called is known, @var{func} is a tree\n\
5341	node (@code{FUNCTION_DECL}) for it; otherwise, @var{func} is a null\n\
5342	pointer. This makes it possible to use a different value-returning\n\
5343	convention for specific functions when all their calls are\n\
5344	known.\n\
5345	\n\
5346	Some target machines have ``register windows'' so that the register in\n\
5347	which a function returns its value is not the same as the one in which\n\
5348	the caller sees the value. For such machines, you should return\n\
5349	different RTX depending on @var{outgoing}.\n\
5350	\n\
5351	@code{TARGET_FUNCTION_VALUE} is not used for return values with\n\
5352	aggregate data types, because these are returned in another way. See\n\
5353	@code{TARGET_STRUCT_VALUE_RTX} and related macros, below.",
5354	rtx, (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing),
5355	default_function_value)
5356
5357	/* Return the rtx for the result of a libcall of mode MODE,
5358	calling the function FN_NAME. */
5359	DEFHOOK
5360	(libcall_value,
5361	"Define this hook if the back-end needs to know the name of the libcall\n\
5362	function in order to determine where the result should be returned.\n\
5363	\n\
5364	The mode of the result is given by @var{mode} and the name of the called\n\
5365	library function is given by @var{fun}. The hook should return an RTX\n\
5366	representing the place where the library function result will be returned.\n\
5367	\n\
5368	If this hook is not defined, then LIBCALL_VALUE will be used.",
5369	rtx, (machine_mode mode, const_rtx fun),
5370	default_libcall_value)
5371
5372	/* Return true if REGNO is a possible register number for
5373	a function value as seen by the caller. */
5374	DEFHOOK
5375	(function_value_regno_p,
5376	"A target hook that return @code{true} if @var{regno} is the number of a hard\n\
5377	register in which the values of called function may come back.\n\
5378	\n\
5379	A register whose use for returning values is limited to serving as the\n\
5380	second of a pair (for a value of type @code{double}, say) need not be\n\
5381	recognized by this target hook.\n\
5382	\n\
5383	If the machine has register windows, so that the caller and the called\n\
5384	function use different registers for the return value, this target hook\n\
5385	should recognize only the caller's register numbers.\n\
5386	\n\
5387	If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.",
5388	bool, (const unsigned int regno),
5389	default_function_value_regno_p)
5390
5391	DEFHOOK
5392	(fntype_abi,
5393	"Return the ABI used by a function with type @var{type}; see the\n\
5394	definition of @code{predefined_function_abi} for details of the ABI\n\
5395	descriptor. Targets only need to define this hook if they support\n\
5396	interoperability between several ABIs in the same translation unit.",
5397	const predefined_function_abi &, (const_tree type),
5398	NULL)
5399
5400	DEFHOOK
5401	(insn_callee_abi,
5402	"This hook returns a description of the ABI used by the target of\n\
5403	call instruction @var{insn}; see the definition of\n\
5404	@code{predefined_function_abi} for details of the ABI descriptor.\n\
5405	Only the global function @code{insn_callee_abi} should call this hook\n\
5406	directly.\n\
5407	\n\
5408	Targets only need to define this hook if they support\n\
5409	interoperability between several ABIs in the same translation unit.",
5410	const predefined_function_abi &, (const rtx_insn *insn),
5411	NULL)
5412
5413	/* ??? Documenting this hook requires a GFDL license grant. */
5414	DEFHOOK_UNDOC
5415	(internal_arg_pointer,
5416	"Return an rtx for the argument pointer incoming to the\
5417	current function.",
5418	rtx, (void),
5419	default_internal_arg_pointer)
5420
5421	/* Update the current function stack boundary if needed. */
5422	DEFHOOK
5423	(update_stack_boundary,
5424	"Define this macro to update the current function stack boundary if\n\
5425	necessary.",
5426	void, (void), NULL)
5427
5428	/* Handle stack alignment and return an rtx for Dynamic Realign
5429	Argument Pointer if necessary. */
5430	DEFHOOK
5431	(get_drap_rtx,
5432	"This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a\n\
5433	different argument pointer register is needed to access the function's\n\
5434	argument list due to stack realignment. Return @code{NULL} if no DRAP\n\
5435	is needed.",
5436	rtx, (void), NULL)
5437
5438	/* Generate instruction sequence to zero call used registers. */
5439	DEFHOOK
5440	(zero_call_used_regs,
5441	"This target hook emits instructions to zero the subset of @var{selected_regs}\n\
5442	that could conceivably contain values that are useful to an attacker.\n\
5443	Return the set of registers that were actually cleared.\n\
5444	\n\
5445	For most targets, the returned set of registers is a subset of\n\
5446	@var{selected_regs}, however, for some of the targets (for example MIPS),\n\
5447	clearing some registers that are in the @var{selected_regs} requires\n\
5448	clearing other call used registers that are not in the @var{selected_regs},\n\
5449	under such situation, the returned set of registers must be a subset of all\n\
5450	call used registers.\n\
5451	\n\
5452	The default implementation uses normal move instructions to zero\n\
5453	all the registers in @var{selected_regs}. Define this hook if the\n\
5454	target has more efficient ways of zeroing certain registers,\n\
5455	or if you believe that certain registers would never contain\n\
5456	values that are useful to an attacker.",
5457	HARD_REG_SET, (HARD_REG_SET selected_regs),
5458	default_zero_call_used_regs)
5459
5460	/* Return true if all function parameters should be spilled to the
5461	stack. */
5462	DEFHOOK
5463	(allocate_stack_slots_for_args,
5464	"When optimization is disabled, this hook indicates whether or not\n\
5465	arguments should be allocated to stack slots. Normally, GCC allocates\n\
5466	stacks slots for arguments when not optimizing in order to make\n\
5467	debugging easier. However, when a function is declared with\n\
5468	@code{__attribute__((naked))}, there is no stack frame, and the compiler\n\
5469	cannot safely move arguments from the registers in which they are passed\n\
5470	to the stack. Therefore, this hook should return true in general, but\n\
5471	false for naked functions. The default implementation always returns true.",
5472	bool, (void),
5473	hook_bool_void_true)
5474
5475	/* Return an rtx for the static chain for FNDECL_OR_TYPE. If INCOMING_P
5476	is true, then it should be for the callee; otherwise for the caller. */
5477	DEFHOOK
5478	(static_chain,
5479	"This hook replaces the use of @code{STATIC_CHAIN_REGNUM} et al for\n\
5480	targets that may use different static chain locations for different\n\
5481	nested functions. This may be required if the target has function\n\
5482	attributes that affect the calling conventions of the function and\n\
5483	those calling conventions use different static chain locations.\n\
5484	\n\
5485	The default version of this hook uses @code{STATIC_CHAIN_REGNUM} et al.\n\
5486	\n\
5487	If the static chain is passed in memory, this hook should be used to\n\
5488	provide rtx giving @code{mem} expressions that denote where they are stored.\n\
5489	Often the @code{mem} expression as seen by the caller will be at an offset\n\
5490	from the stack pointer and the @code{mem} expression as seen by the callee\n\
5491	will be at an offset from the frame pointer.\n\
5492	@findex stack_pointer_rtx\n\
5493	@findex frame_pointer_rtx\n\
5494	@findex arg_pointer_rtx\n\
5495	The variables @code{stack_pointer_rtx}, @code{frame_pointer_rtx}, and\n\
5496	@code{arg_pointer_rtx} will have been initialized and should be used\n\
5497	to refer to those items.",
5498	rtx, (const_tree fndecl_or_type, bool incoming_p),
5499	default_static_chain)
5500
5501	/* Fill in the trampoline at MEM with a call to FNDECL and a
5502	static chain value of CHAIN. */
5503	DEFHOOK
5504	(trampoline_init,
5505	"This hook is called to initialize a trampoline.\n\
5506	@var{m_tramp} is an RTX for the memory block for the trampoline; @var{fndecl}\n\
5507	is the @code{FUNCTION_DECL} for the nested function; @var{static_chain} is an\n\
5508	RTX for the static chain value that should be passed to the function\n\
5509	when it is called.\n\
5510	\n\
5511	If the target defines @code{TARGET_ASM_TRAMPOLINE_TEMPLATE}, then the\n\
5512	first thing this hook should do is emit a block move into @var{m_tramp}\n\
5513	from the memory block returned by @code{assemble_trampoline_template}.\n\
5514	Note that the block move need only cover the constant parts of the\n\
5515	trampoline. If the target isolates the variable parts of the trampoline\n\
5516	to the end, not all @code{TRAMPOLINE_SIZE} bytes need be copied.\n\
5517	\n\
5518	If the target requires any other actions, such as flushing caches\n\
5519	(possibly calling function maybe_emit_call_builtin___clear_cache) or\n\
5520	enabling stack execution, these actions should be performed after\n\
5521	initializing the trampoline proper.",
5522	void, (rtx m_tramp, tree fndecl, rtx static_chain),
5523	default_trampoline_init)
5524
5525	/* Emit a call to a function to clear the instruction cache. */
5526	DEFHOOK
5527	(emit_call_builtin___clear_cache,
5528	"On targets that do not define a @code{clear_cache} insn expander,\n\
5529	but that define the @code{CLEAR_CACHE_INSN} macro,\n\
5530	maybe_emit_call_builtin___clear_cache relies on this target hook\n\
5531	to clear an address range in the instruction cache.\n\
5532	\n\
5533	The default implementation calls the @code{__clear_cache} builtin,\n\
5534	taking the assembler name from the builtin declaration. Overriding\n\
5535	definitions may call alternate functions, with alternate calling\n\
5536	conventions, or emit alternate RTX to perform the job.",
5537	void, (rtx begin, rtx end),
5538	default_emit_call_builtin___clear_cache)
5539
5540	/* Adjust the address of the trampoline in a target-specific way. */
5541	DEFHOOK
5542	(trampoline_adjust_address,
5543	"This hook should perform any machine-specific adjustment in\n\
5544	the address of the trampoline. Its argument contains the address of the\n\
5545	memory block that was passed to @code{TARGET_TRAMPOLINE_INIT}. In case\n\
5546	the address to be used for a function call should be different from the\n\
5547	address at which the template was stored, the different address should\n\
5548	be returned; otherwise @var{addr} should be returned unchanged.\n\
5549	If this hook is not defined, @var{addr} will be used for function calls.",
5550	rtx, (rtx addr), NULL)
5551
5552	DEFHOOKPOD
5553	(custom_function_descriptors,
5554	"If the target can use GCC's generic descriptor mechanism for nested\n\
5555	functions, define this hook to a power of 2 representing an unused bit\n\
5556	in function pointers which can be used to differentiate descriptors at\n\
5557	run time. This value gives the number of bytes by which descriptor\n\
5558	pointers are misaligned compared to function pointers. For example, on\n\
5559	targets that require functions to be aligned to a 4-byte boundary, a\n\
5560	value of either 1 or 2 is appropriate unless the architecture already\n\
5561	reserves the bit for another purpose, such as on ARM.\n\
5562	\n\
5563	Define this hook to 0 if the target implements ABI support for\n\
5564	function descriptors in its standard calling sequence, like for example\n\
5565	HPPA or IA-64.\n\
5566	\n\
5567	Using descriptors for nested functions\n\
5568	eliminates the need for trampolines that reside on the stack and require\n\
5569	it to be made executable.",
5570	int, -1)
5571
5572	/* Return the number of bytes of its own arguments that a function
5573	pops on returning, or 0 if the function pops no arguments and the
5574	caller must therefore pop them all after the function returns. */
5575	/* ??? tm.texi has no types for the parameters. */
5576	DEFHOOK
5577	(return_pops_args,
5578	"This target hook returns the number of bytes of its own arguments that\n\
5579	a function pops on returning, or 0 if the function pops no arguments\n\
5580	and the caller must therefore pop them all after the function returns.\n\
5581	\n\
5582	@var{fundecl} is a C variable whose value is a tree node that describes\n\
5583	the function in question. Normally it is a node of type\n\
5584	@code{FUNCTION_DECL} that describes the declaration of the function.\n\
5585	From this you can obtain the @code{DECL_ATTRIBUTES} of the function.\n\
5586	\n\
5587	@var{funtype} is a C variable whose value is a tree node that\n\
5588	describes the function in question. Normally it is a node of type\n\
5589	@code{FUNCTION_TYPE} that describes the data type of the function.\n\
5590	From this it is possible to obtain the data types of the value and\n\
5591	arguments (if known).\n\
5592	\n\
5593	When a call to a library function is being considered, @var{fundecl}\n\
5594	will contain an identifier node for the library function. Thus, if\n\
5595	you need to distinguish among various library functions, you can do so\n\
5596	by their names. Note that ``library function'' in this context means\n\
5597	a function used to perform arithmetic, whose name is known specially\n\
5598	in the compiler and was not mentioned in the C code being compiled.\n\
5599	\n\
5600	@var{size} is the number of bytes of arguments passed on the\n\
5601	stack. If a variable number of bytes is passed, it is zero, and\n\
5602	argument popping will always be the responsibility of the calling function.\n\
5603	\n\
5604	On the VAX, all functions always pop their arguments, so the definition\n\
5605	of this macro is @var{size}. On the 68000, using the standard\n\
5606	calling convention, no functions pop their arguments, so the value of\n\
5607	the macro is always 0 in this case. But an alternative calling\n\
5608	convention is available in which functions that take a fixed number of\n\
5609	arguments pop them but other functions (such as @code{printf}) pop\n\
5610	nothing (the caller pops all). When this convention is in use,\n\
5611	@var{funtype} is examined to determine whether a function takes a fixed\n\
5612	number of arguments.",
5613	poly_int64, (tree fundecl, tree funtype, poly_int64 size),
5614	default_return_pops_args)
5615
5616	/* Return a mode wide enough to copy any function value that might be
5617	returned. */
5618	DEFHOOK
5619	(get_raw_result_mode,
5620	"This target hook returns the mode to be used when accessing raw return\n\
5621	registers in @code{__builtin_return}. Define this macro if the value\n\
5622	in @var{reg_raw_mode} is not correct. Use @code{VOIDmode} if a register\n\
5623	should be ignored for @code{__builtin_return} purposes.",
5624	fixed_size_mode, (int regno),
5625	default_get_reg_raw_mode)
5626
5627	/* Return a mode wide enough to copy any argument value that might be
5628	passed. */
5629	DEFHOOK
5630	(get_raw_arg_mode,
5631	"This target hook returns the mode to be used when accessing raw argument\n\
5632	registers in @code{__builtin_apply_args}. Define this macro if the value\n\
5633	in @var{reg_raw_mode} is not correct. Use @code{VOIDmode} if a register\n\
5634	should be ignored for @code{__builtin_apply_args} purposes.",
5635	fixed_size_mode, (int regno),
5636	default_get_reg_raw_mode)
5637
5638	/* Return true if a type is an empty record. */
5639	DEFHOOK
5640	(empty_record_p,
5641	"This target hook returns true if the type is an empty record. The default\n\
5642	is to return @code{false}.",
5643	bool, (const_tree type),
5644	hook_bool_const_tree_false)
5645
5646	/* Warn about the change in empty class parameter passing ABI. */
5647	DEFHOOK
5648	(warn_parameter_passing_abi,
5649	"This target hook warns about the change in empty class parameter passing\n\
5650	ABI.",
5651	void, (cumulative_args_t ca, tree type),
5652	hook_void_CUMULATIVE_ARGS_tree)
5653
5654	HOOK_VECTOR_END (calls)
5655
5656	DEFHOOK
5657	(use_pseudo_pic_reg,
5658	"This hook should return 1 in case pseudo register should be created\n\
5659	for pic_offset_table_rtx during function expand.",
5660	bool, (void),
5661	hook_bool_void_false)
5662
5663	DEFHOOK
5664	(init_pic_reg,
5665	"Perform a target dependent initialization of pic_offset_table_rtx.\n\
5666	This hook is called at the start of register allocation.",
5667	void, (void),
5668	hook_void_void)
5669
5670	/* Return the diagnostic message string if conversion from FROMTYPE
5671	to TOTYPE is not allowed, NULL otherwise. */
5672	DEFHOOK
5673	(invalid_conversion,
5674	"If defined, this macro returns the diagnostic message when it is\n\
5675	invalid to convert from @var{fromtype} to @var{totype}, or @code{NULL}\n\
5676	if validity should be determined by the front end.",
5677	const char *, (const_tree fromtype, const_tree totype),
5678	hook_constcharptr_const_tree_const_tree_null)
5679
5680	/* Return the diagnostic message string if the unary operation OP is
5681	not permitted on TYPE, NULL otherwise. */
5682	DEFHOOK
5683	(invalid_unary_op,
5684	"If defined, this macro returns the diagnostic message when it is\n\
5685	invalid to apply operation @var{op} (where unary plus is denoted by\n\
5686	@code{CONVERT_EXPR}) to an operand of type @var{type}, or @code{NULL}\n\
5687	if validity should be determined by the front end.",
5688	const char *, (int op, const_tree type),
5689	hook_constcharptr_int_const_tree_null)
5690
5691	/* Return the diagnostic message string if the binary operation OP
5692	is not permitted on TYPE1 and TYPE2, NULL otherwise. */
5693	DEFHOOK
5694	(invalid_binary_op,
5695	"If defined, this macro returns the diagnostic message when it is\n\
5696	invalid to apply operation @var{op} to operands of types @var{type1}\n\
5697	and @var{type2}, or @code{NULL} if validity should be determined by\n\
5698	the front end.",
5699	const char *, (int op, const_tree type1, const_tree type2),
5700	hook_constcharptr_int_const_tree_const_tree_null)
5701
5702	/* If values of TYPE are promoted to some other type when used in
5703	expressions (analogous to the integer promotions), return that type,
5704	or NULL_TREE otherwise. */
5705	DEFHOOK
5706	(promoted_type,
5707	"If defined, this target hook returns the type to which values of\n\
5708	@var{type} should be promoted when they appear in expressions,\n\
5709	analogous to the integer promotions, or @code{NULL_TREE} to use the\n\
5710	front end's normal promotion rules. This hook is useful when there are\n\
5711	target-specific types with special promotion rules.\n\
5712	This is currently used only by the C and C++ front ends.",
5713	tree, (const_tree type),
5714	hook_tree_const_tree_null)
5715
5716	/* Convert EXPR to TYPE, if target-specific types with special conversion
5717	rules are involved. Return the converted expression, or NULL to apply
5718	the standard conversion rules. */
5719	DEFHOOK
5720	(convert_to_type,
5721	"If defined, this hook returns the result of converting @var{expr} to\n\
5722	@var{type}. It should return the converted expression,\n\
5723	or @code{NULL_TREE} to apply the front end's normal conversion rules.\n\
5724	This hook is useful when there are target-specific types with special\n\
5725	conversion rules.\n\
5726	This is currently used only by the C and C++ front ends.",
5727	tree, (tree type, tree expr),
5728	hook_tree_tree_tree_null)
5729
5730	DEFHOOK
5731	(verify_type_context,
5732	"If defined, this hook returns false if there is a target-specific reason\n\
5733	why type @var{type} cannot be used in the source language context described\n\
5734	by @var{context}. When @var{silent_p} is false, the hook also reports an\n\
5735	error against @var{loc} for invalid uses of @var{type}.\n\
5736	\n\
5737	Calls to this hook should be made through the global function\n\
5738	@code{verify_type_context}, which makes the @var{silent_p} parameter\n\
5739	default to false and also handles @code{error_mark_node}.\n\
5740	\n\
5741	The default implementation always returns true.",
5742	bool, (location_t loc, type_context_kind context, const_tree type,
5743	bool silent_p),
5744	NULL)
5745
5746	DEFHOOK
5747	(can_change_mode_class,
5748	"This hook returns true if it is possible to bitcast values held in\n\
5749	registers of class @var{rclass} from mode @var{from} to mode @var{to}\n\
5750	and if doing so preserves the low-order bits that are common to both modes.\n\
5751	The result is only meaningful if @var{rclass} has registers that can hold\n\
5752	both @code{from} and @code{to}. The default implementation returns true.\n\
5753	\n\
5754	As an example of when such bitcasting is invalid, loading 32-bit integer or\n\
5755	floating-point objects into floating-point registers on Alpha extends them\n\
5756	to 64 bits. Therefore loading a 64-bit object and then storing it as a\n\
5757	32-bit object does not store the low-order 32 bits, as would be the case\n\
5758	for a normal register. Therefore, @file{alpha.h} defines\n\
5759	@code{TARGET_CAN_CHANGE_MODE_CLASS} to return:\n\
5760	\n\
5761	@smallexample\n\
5762	(GET_MODE_SIZE (from) == GET_MODE_SIZE (to)\n\
5763	|| !reg_classes_intersect_p (FLOAT_REGS, rclass))\n\
5764	@end smallexample\n\
5765	\n\
5766	Even if storing from a register in mode @var{to} would be valid,\n\
5767	if both @var{from} and @code{raw_reg_mode} for @var{rclass} are wider\n\
5768	than @code{word_mode}, then we must prevent @var{to} narrowing the\n\
5769	mode. This happens when the middle-end assumes that it can load\n\
5770	or store pieces of an @var{N}-word pseudo, and that the pseudo will\n\
5771	eventually be allocated to @var{N} @code{word_mode} hard registers.\n\
5772	Failure to prevent this kind of mode change will result in the\n\
5773	entire @code{raw_reg_mode} being modified instead of the partial\n\
5774	value that the middle-end intended.",
5775	bool, (machine_mode from, machine_mode to, reg_class_t rclass),
5776	hook_bool_mode_mode_reg_class_t_true)
5777
5778	/* Change pseudo allocno class calculated by IRA. */
5779	DEFHOOK
5780	(ira_change_pseudo_allocno_class,
5781	"A target hook which can change allocno class for given pseudo from\n\
5782	allocno and best class calculated by IRA.\n\
5783	\n\
5784	The default version of this target hook always returns given class.",
5785	reg_class_t, (int, reg_class_t, reg_class_t),
5786	default_ira_change_pseudo_allocno_class)
5787
5788	/* Return true if we use LRA instead of reload. */
5789	DEFHOOK
5790	(lra_p,
5791	"A target hook which returns true if we use LRA instead of reload pass.\n\
5792	\n\
5793	The default version of this target hook returns true. New ports\n\
5794	should use LRA, and existing ports are encouraged to convert.",
5795	bool, (void),
5796	default_lra_p)
5797
5798	/* Return register priority of given hard regno for the current target. */
5799	DEFHOOK
5800	(register_priority,
5801	"A target hook which returns the register priority number to which the\n\
5802	register @var{hard_regno} belongs to. The bigger the number, the\n\
5803	more preferable the hard register usage (when all other conditions are\n\
5804	the same). This hook can be used to prefer some hard register over\n\
5805	others in LRA. For example, some x86-64 register usage needs\n\
5806	additional prefix which makes instructions longer. The hook can\n\
5807	return lower priority number for such registers make them less favorable\n\
5808	and as result making the generated code smaller.\n\
5809	\n\
5810	The default version of this target hook returns always zero.",
5811	int, (int),
5812	default_register_priority)
5813
5814	/* Return true if we need register usage leveling. */
5815	DEFHOOK
5816	(register_usage_leveling_p,
5817	"A target hook which returns true if we need register usage leveling.\n\
5818	That means if a few hard registers are equally good for the\n\
5819	assignment, we choose the least used hard register. The register\n\
5820	usage leveling may be profitable for some targets. Don't use the\n\
5821	usage leveling for targets with conditional execution or targets\n\
5822	with big register files as it hurts if-conversion and cross-jumping\n\
5823	optimizations.\n\
5824	\n\
5825	The default version of this target hook returns always false.",
5826	bool, (void),
5827	default_register_usage_leveling_p)
5828
5829	/* Return true if maximal address displacement can be different. */
5830	DEFHOOK
5831	(different_addr_displacement_p,
5832	"A target hook which returns true if an address with the same structure\n\
5833	can have different maximal legitimate displacement. For example, the\n\
5834	displacement can depend on memory mode or on operand combinations in\n\
5835	the insn.\n\
5836	\n\
5837	The default version of this target hook returns always false.",
5838	bool, (void),
5839	default_different_addr_displacement_p)
5840
5841	/* Determine class for spilling pseudos of given mode into registers
5842	instead of memory. */
5843	DEFHOOK
5844	(spill_class,
5845	"This hook defines a class of registers which could be used for spilling\n\
5846	pseudos of the given mode and class, or @code{NO_REGS} if only memory\n\
5847	should be used. Not defining this hook is equivalent to returning\n\
5848	@code{NO_REGS} for all inputs.",
5849	reg_class_t, (reg_class_t, machine_mode),
5850	NULL)
5851
5852	/* Determine an additional allocno class. */
5853	DEFHOOK
5854	(additional_allocno_class_p,
5855	"This hook should return @code{true} if given class of registers should\n\
5856	be an allocno class in any way. Usually RA uses only one register\n\
5857	class from all classes containing the same register set. In some\n\
5858	complicated cases, you need to have two or more such classes as\n\
5859	allocno ones for RA correct work. Not defining this hook is\n\
5860	equivalent to returning @code{false} for all inputs.",
5861	bool, (reg_class_t),
5862	hook_bool_reg_class_t_false)
5863
5864	DEFHOOK
5865	(cstore_mode,
5866	"This hook defines the machine mode to use for the boolean result of\n\
5867	conditional store patterns. The ICODE argument is the instruction code\n\
5868	for the cstore being performed. Not definiting this hook is the same\n\
5869	as accepting the mode encoded into operand 0 of the cstore expander\n\
5870	patterns.",
5871	scalar_int_mode, (enum insn_code icode),
5872	default_cstore_mode)
5873
5874	/* This target hook allows the backend to compute the register pressure
5875	classes to use. */
5876	DEFHOOK
5877	(compute_pressure_classes,
5878	"A target hook which lets a backend compute the set of pressure classes to\n\
5879	be used by those optimization passes which take register pressure into\n\
5880	account, as opposed to letting IRA compute them. It returns the number of\n\
5881	register classes stored in the array @var{pressure_classes}.",
5882	int, (enum reg_class *pressure_classes), NULL)
5883
5884	/* True if a structure, union or array with MODE containing FIELD should
5885	be accessed using BLKmode. */
5886	DEFHOOK
5887	(member_type_forces_blk,
5888	"Return true if a structure, union or array containing @var{field} should\n\
5889	be accessed using @code{BLKMODE}.\n\
5890	\n\
5891	If @var{field} is the only field in the structure, @var{mode} is its\n\
5892	mode, otherwise @var{mode} is VOIDmode. @var{mode} is provided in the\n\
5893	case where structures of one field would require the structure's mode to\n\
5894	retain the field's mode.\n\
5895	\n\
5896	Normally, this is not needed.",
5897	bool, (const_tree field, machine_mode mode),
5898	default_member_type_forces_blk)
5899
5900	/* See tree-ssa-math-opts.cc:divmod_candidate_p for conditions
5901	that gate the divod transform. */
5902	DEFHOOK
5903	(expand_divmod_libfunc,
5904	"Define this hook for enabling divmod transform if the port does not have\n\
5905	hardware divmod insn but defines target-specific divmod libfuncs.",
5906	void, (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem),
5907	NULL)
5908
5909	/* Return the class for a secondary reload, and fill in extra information. */
5910	DEFHOOK
5911	(secondary_reload,
5912	"Many machines have some registers that cannot be copied directly to or\n\
5913	from memory or even from other types of registers. An example is the\n\
5914	@samp{MQ} register, which on most machines, can only be copied to or\n\
5915	from general registers, but not memory. Below, we shall be using the\n\
5916	term 'intermediate register' when a move operation cannot be performed\n\
5917	directly, but has to be done by copying the source into the intermediate\n\
5918	register first, and then copying the intermediate register to the\n\
5919	destination. An intermediate register always has the same mode as\n\
5920	source and destination. Since it holds the actual value being copied,\n\
5921	reload might apply optimizations to re-use an intermediate register\n\
5922	and eliding the copy from the source when it can determine that the\n\
5923	intermediate register still holds the required value.\n\
5924	\n\
5925	Another kind of secondary reload is required on some machines which\n\
5926	allow copying all registers to and from memory, but require a scratch\n\
5927	register for stores to some memory locations (e.g., those with symbolic\n\
5928	address on the RT, and those with certain symbolic address on the SPARC\n\
5929	when compiling PIC)@. Scratch registers need not have the same mode\n\
5930	as the value being copied, and usually hold a different value than\n\
5931	that being copied. Special patterns in the md file are needed to\n\
5932	describe how the copy is performed with the help of the scratch register;\n\
5933	these patterns also describe the number, register class(es) and mode(s)\n\
5934	of the scratch register(s).\n\
5935	\n\
5936	In some cases, both an intermediate and a scratch register are required.\n\
5937	\n\
5938	For input reloads, this target hook is called with nonzero @var{in_p},\n\
5939	and @var{x} is an rtx that needs to be copied to a register of class\n\
5940	@var{reload_class} in @var{reload_mode}. For output reloads, this target\n\
5941	hook is called with zero @var{in_p}, and a register of class @var{reload_class}\n\
5942	needs to be copied to rtx @var{x} in @var{reload_mode}.\n\
5943	\n\
5944	If copying a register of @var{reload_class} from/to @var{x} requires\n\
5945	an intermediate register, the hook @code{secondary_reload} should\n\
5946	return the register class required for this intermediate register.\n\
5947	If no intermediate register is required, it should return NO_REGS.\n\
5948	If more than one intermediate register is required, describe the one\n\
5949	that is closest in the copy chain to the reload register.\n\
5950	\n\
5951	If scratch registers are needed, you also have to describe how to\n\
5952	perform the copy from/to the reload register to/from this\n\
5953	closest intermediate register. Or if no intermediate register is\n\
5954	required, but still a scratch register is needed, describe the\n\
5955	copy from/to the reload register to/from the reload operand @var{x}.\n\
5956	\n\
5957	You do this by setting @code{sri->icode} to the instruction code of a pattern\n\
5958	in the md file which performs the move. Operands 0 and 1 are the output\n\
5959	and input of this copy, respectively. Operands from operand 2 onward are\n\
5960	for scratch operands. These scratch operands must have a mode, and a\n\
5961	single-register-class\n\
5962	@c [later: or memory]\n\
5963	output constraint.\n\
5964	\n\
5965	When an intermediate register is used, the @code{secondary_reload}\n\
5966	hook will be called again to determine how to copy the intermediate\n\
5967	register to/from the reload operand @var{x}, so your hook must also\n\
5968	have code to handle the register class of the intermediate operand.\n\
5969	\n\
5970	@c [For later: maybe we'll allow multi-alternative reload patterns -\n\
5971	@c the port maintainer could name a mov<mode> pattern that has clobbers -\n\
5972	@c and match the constraints of input and output to determine the required\n\
5973	@c alternative. A restriction would be that constraints used to match\n\
5974	@c against reloads registers would have to be written as register class\n\
5975	@c constraints, or we need a new target macro / hook that tells us if an\n\
5976	@c arbitrary constraint can match an unknown register of a given class.\n\
5977	@c Such a macro / hook would also be useful in other places.]\n\
5978	\n\
5979	\n\
5980	@var{x} might be a pseudo-register or a @code{subreg} of a\n\
5981	pseudo-register, which could either be in a hard register or in memory.\n\
5982	Use @code{true_regnum} to find out; it will return @minus{}1 if the pseudo is\n\
5983	in memory and the hard register number if it is in a register.\n\
5984	\n\
5985	Scratch operands in memory (constraint @code{\"=m\"} / @code{\"=&m\"}) are\n\
5986	currently not supported. For the time being, you will have to continue\n\
5987	to use @code{TARGET_SECONDARY_MEMORY_NEEDED} for that purpose.\n\
5988	\n\
5989	@code{copy_cost} also uses this target hook to find out how values are\n\
5990	copied. If you want it to include some extra cost for the need to allocate\n\
5991	(a) scratch register(s), set @code{sri->extra_cost} to the additional cost.\n\
5992	Or if two dependent moves are supposed to have a lower cost than the sum\n\
5993	of the individual moves due to expected fortuitous scheduling and/or special\n\
5994	forwarding logic, you can set @code{sri->extra_cost} to a negative amount.",
5995	reg_class_t,
5996	(bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode,
5997	secondary_reload_info *sri),
5998	default_secondary_reload)
5999
6000	DEFHOOK
6001	(secondary_memory_needed,
6002	"Certain machines have the property that some registers cannot be copied\n\
6003	to some other registers without using memory. Define this hook on\n\
6004	those machines to return true if objects of mode @var{m} in registers\n\
6005	of @var{class1} can only be copied to registers of class @var{class2} by\n\
6006	storing a register of @var{class1} into memory and loading that memory\n\
6007	location into a register of @var{class2}. The default definition returns\n\
6008	false for all inputs.",
6009	bool, (machine_mode mode, reg_class_t class1, reg_class_t class2),
6010	hook_bool_mode_reg_class_t_reg_class_t_false)
6011
6012	DEFHOOK
6013	(secondary_memory_needed_mode,
6014	"If @code{TARGET_SECONDARY_MEMORY_NEEDED} tells the compiler to use memory\n\
6015	when moving between two particular registers of mode @var{mode},\n\
6016	this hook specifies the mode that the memory should have.\n\
6017	\n\
6018	The default depends on @code{TARGET_LRA_P}. Without LRA, the default\n\
6019	is to use a word-sized mode for integral modes that are smaller than a\n\
6020	a word. This is right thing to do on most machines because it ensures\n\
6021	that all bits of the register are copied and prevents accesses to the\n\
6022	registers in a narrower mode, which some machines prohibit for\n\
6023	floating-point registers.\n\
6024	\n\
6025	However, this default behavior is not correct on some machines, such as\n\
6026	the DEC Alpha, that store short integers in floating-point registers\n\
6027	differently than in integer registers. On those machines, the default\n\
6028	widening will not work correctly and you must define this hook to\n\
6029	suppress that widening in some cases. See the file @file{alpha.cc} for\n\
6030	details.\n\
6031	\n\
6032	With LRA, the default is to use @var{mode} unmodified.",
6033	machine_mode, (machine_mode mode),
6034	default_secondary_memory_needed_mode)
6035
6036	/* Given an rtx X being reloaded into a reg required to be in class CLASS,
6037	return the class of reg to actually use. */
6038	DEFHOOK
6039	(preferred_reload_class,
6040	"A target hook that places additional restrictions on the register class\n\
6041	to use when it is necessary to copy value @var{x} into a register in class\n\
6042	@var{rclass}. The value is a register class; perhaps @var{rclass}, or perhaps\n\
6043	another, smaller class.\n\
6044	\n\
6045	The default version of this hook always returns value of @code{rclass} argument.\n\
6046	\n\
6047	Sometimes returning a more restrictive class makes better code. For\n\
6048	example, on the 68000, when @var{x} is an integer constant that is in range\n\
6049	for a @samp{moveq} instruction, the value of this macro is always\n\
6050	@code{DATA_REGS} as long as @var{rclass} includes the data registers.\n\
6051	Requiring a data register guarantees that a @samp{moveq} will be used.\n\
6052	\n\
6053	One case where @code{TARGET_PREFERRED_RELOAD_CLASS} must not return\n\
6054	@var{rclass} is if @var{x} is a legitimate constant which cannot be\n\
6055	loaded into some register class. By returning @code{NO_REGS} you can\n\
6056	force @var{x} into a memory location. For example, rs6000 can load\n\
6057	immediate values into general-purpose registers, but does not have an\n\
6058	instruction for loading an immediate value into a floating-point\n\
6059	register, so @code{TARGET_PREFERRED_RELOAD_CLASS} returns @code{NO_REGS} when\n\
6060	@var{x} is a floating-point constant. If the constant can't be loaded\n\
6061	into any kind of register, code generation will be better if\n\
6062	@code{TARGET_LEGITIMATE_CONSTANT_P} makes the constant illegitimate instead\n\
6063	of using @code{TARGET_PREFERRED_RELOAD_CLASS}.\n\
6064	\n\
6065	If an insn has pseudos in it after register allocation, reload will go\n\
6066	through the alternatives and call repeatedly @code{TARGET_PREFERRED_RELOAD_CLASS}\n\
6067	to find the best one. Returning @code{NO_REGS}, in this case, makes\n\
6068	reload add a @code{!} in front of the constraint: the x86 back-end uses\n\
6069	this feature to discourage usage of 387 registers when math is done in\n\
6070	the SSE registers (and vice versa).",
6071	reg_class_t,
6072	(rtx x, reg_class_t rclass),
6073	default_preferred_reload_class)
6074
6075	/* Like TARGET_PREFERRED_RELOAD_CLASS, but for output reloads instead of
6076	input reloads. */
6077	DEFHOOK
6078	(preferred_output_reload_class,
6079	"Like @code{TARGET_PREFERRED_RELOAD_CLASS}, but for output reloads instead of\n\
6080	input reloads.\n\
6081	\n\
6082	The default version of this hook always returns value of @code{rclass}\n\
6083	argument.\n\
6084	\n\
6085	You can also use @code{TARGET_PREFERRED_OUTPUT_RELOAD_CLASS} to discourage\n\
6086	reload from using some alternatives, like @code{TARGET_PREFERRED_RELOAD_CLASS}.",
6087	reg_class_t,
6088	(rtx x, reg_class_t rclass),
6089	default_preferred_output_reload_class)
6090
6091	DEFHOOK
6092	(select_early_remat_modes,
6093	"On some targets, certain modes cannot be held in registers around a\n\
6094	standard ABI call and are relatively expensive to spill to the stack.\n\
6095	The early rematerialization pass can help in such cases by aggressively\n\
6096	recomputing values after calls, so that they don't need to be spilled.\n\
6097	\n\
6098	This hook returns the set of such modes by setting the associated bits\n\
6099	in @var{modes}. The default implementation selects no modes, which has\n\
6100	the effect of disabling the early rematerialization pass.",
6101	void, (sbitmap modes),
6102	default_select_early_remat_modes)
6103
6104	DEFHOOK
6105	(class_likely_spilled_p,
6106	"A target hook which returns @code{true} if pseudos that have been assigned\n\
6107	to registers of class @var{rclass} would likely be spilled because\n\
6108	registers of @var{rclass} are needed for spill registers.\n\
6109	\n\
6110	The default version of this target hook returns @code{true} if @var{rclass}\n\
6111	has exactly one register and @code{false} otherwise. On most machines, this\n\
6112	default should be used. For generally register-starved machines, such as\n\
6113	i386, or machines with right register constraints, such as SH, this hook\n\
6114	can be used to avoid excessive spilling.\n\
6115	\n\
6116	This hook is also used by some of the global intra-procedural code\n\
6117	transformations to throtle code motion, to avoid increasing register\n\
6118	pressure.",
6119	bool, (reg_class_t rclass),
6120	default_class_likely_spilled_p)
6121
6122	/* Return the maximum number of consecutive registers
6123	needed to represent mode MODE in a register of class RCLASS. */
6124	DEFHOOK
6125	(class_max_nregs,
6126	"A target hook returns the maximum number of consecutive registers\n\
6127	of class @var{rclass} needed to hold a value of mode @var{mode}.\n\
6128	\n\
6129	This is closely related to the macro @code{TARGET_HARD_REGNO_NREGS}.\n\
6130	In fact, the value returned by @code{TARGET_CLASS_MAX_NREGS (@var{rclass},\n\
6131	@var{mode})} target hook should be the maximum value of\n\
6132	@code{TARGET_HARD_REGNO_NREGS (@var{regno}, @var{mode})} for all @var{regno}\n\
6133	values in the class @var{rclass}.\n\
6134	\n\
6135	This target hook helps control the handling of multiple-word values\n\
6136	in the reload pass.\n\
6137	\n\
6138	The default version of this target hook returns the size of @var{mode}\n\
6139	in words.",
6140	unsigned char, (reg_class_t rclass, machine_mode mode),
6141	default_class_max_nregs)
6142
6143	DEFHOOK
6144	(preferred_rename_class,
6145	"A target hook that places additional preference on the register\n\
6146	class to use when it is necessary to rename a register in class\n\
6147	@var{rclass} to another class, or perhaps @var{NO_REGS}, if no\n\
6148	preferred register class is found or hook @code{preferred_rename_class}\n\
6149	is not implemented.\n\
6150	Sometimes returning a more restrictive class makes better code. For\n\
6151	example, on ARM, thumb-2 instructions using @code{LO_REGS} may be\n\
6152	smaller than instructions using @code{GENERIC_REGS}. By returning\n\
6153	@code{LO_REGS} from @code{preferred_rename_class}, code size can\n\
6154	be reduced.",
6155	reg_class_t, (reg_class_t rclass),
6156	default_preferred_rename_class)
6157
6158	/* This target hook allows the backend to avoid unsafe substitution
6159	during register allocation. */
6160	DEFHOOK
6161	(cannot_substitute_mem_equiv_p,
6162	"A target hook which returns @code{true} if @var{subst} can't\n\
6163	substitute safely pseudos with equivalent memory values during\n\
6164	register allocation.\n\
6165	The default version of this target hook returns @code{false}.\n\
6166	On most machines, this default should be used. For generally\n\
6167	machines with non orthogonal register usage for addressing, such\n\
6168	as SH, this hook can be used to avoid excessive spilling.",
6169	bool, (rtx subst),
6170	hook_bool_rtx_false)
6171
6172	/* This target hook allows the backend to legitimize base plus
6173	displacement addressing. */
6174	DEFHOOK
6175	(legitimize_address_displacement,
6176	"This hook tries to split address offset @var{orig_offset} into\n\
6177	two parts: one that should be added to the base address to create\n\
6178	a local anchor point, and an additional offset that can be applied\n\
6179	to the anchor to address a value of mode @var{mode}. The idea is that\n\
6180	the local anchor could be shared by other accesses to nearby locations.\n\
6181	\n\
6182	The hook returns true if it succeeds, storing the offset of the\n\
6183	anchor from the base in @var{offset1} and the offset of the final address\n\
6184	from the anchor in @var{offset2}. The default implementation returns false.",
6185	bool, (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode),
6186	default_legitimize_address_displacement)
6187
6188	/* This target hook allows the backend to perform additional
6189	processing while initializing for variable expansion. */
6190	DEFHOOK
6191	(expand_to_rtl_hook,
6192	"This hook is called just before expansion into rtl, allowing the target\n\
6193	to perform additional initializations or analysis before the expansion.\n\
6194	For example, the rs6000 port uses it to allocate a scratch stack slot\n\
6195	for use in copying SDmode values between memory and floating point\n\
6196	registers whenever the function being expanded has any SDmode\n\
6197	usage.",
6198	void, (void),
6199	hook_void_void)
6200
6201	/* This target hook allows the backend to perform additional
6202	instantiations on rtx that are not actually in insns yet,
6203	but will be later. */
6204	DEFHOOK
6205	(instantiate_decls,
6206	"This hook allows the backend to perform additional instantiations on rtl\n\
6207	that are not actually in any insns yet, but will be later.",
6208	void, (void),
6209	hook_void_void)
6210
6211	DEFHOOK
6212	(hard_regno_nregs,
6213	"This hook returns the number of consecutive hard registers, starting\n\
6214	at register number @var{regno}, required to hold a value of mode\n\
6215	@var{mode}. This hook must never return zero, even if a register\n\
6216	cannot hold the requested mode - indicate that with\n\
6217	@code{TARGET_HARD_REGNO_MODE_OK} and/or\n\
6218	@code{TARGET_CAN_CHANGE_MODE_CLASS} instead.\n\
6219	\n\
6220	The default definition returns the number of words in @var{mode}.",
6221	unsigned int, (unsigned int regno, machine_mode mode),
6222	default_hard_regno_nregs)
6223
6224	DEFHOOK
6225	(hard_regno_mode_ok,
6226	"This hook returns true if it is permissible to store a value\n\
6227	of mode @var{mode} in hard register number @var{regno} (or in several\n\
6228	registers starting with that one). The default definition returns true\n\
6229	unconditionally.\n\
6230	\n\
6231	You need not include code to check for the numbers of fixed registers,\n\
6232	because the allocation mechanism considers them to be always occupied.\n\
6233	\n\
6234	@cindex register pairs\n\
6235	On some machines, double-precision values must be kept in even/odd\n\
6236	register pairs. You can implement that by defining this hook to reject\n\
6237	odd register numbers for such modes.\n\
6238	\n\
6239	The minimum requirement for a mode to be OK in a register is that the\n\
6240	@samp{mov@var{mode}} instruction pattern support moves between the\n\
6241	register and other hard register in the same class and that moving a\n\
6242	value into the register and back out not alter it.\n\
6243	\n\
6244	Since the same instruction used to move @code{word_mode} will work for\n\
6245	all narrower integer modes, it is not necessary on any machine for\n\
6246	this hook to distinguish between these modes, provided you define\n\
6247	patterns @samp{movhi}, etc., to take advantage of this. This is\n\
6248	useful because of the interaction between @code{TARGET_HARD_REGNO_MODE_OK}\n\
6249	and @code{TARGET_MODES_TIEABLE_P}; it is very desirable for all integer\n\
6250	modes to be tieable.\n\
6251	\n\
6252	Many machines have special registers for floating point arithmetic.\n\
6253	Often people assume that floating point machine modes are allowed only\n\
6254	in floating point registers. This is not true. Any registers that\n\
6255	can hold integers can safely @emph{hold} a floating point machine\n\
6256	mode, whether or not floating arithmetic can be done on it in those\n\
6257	registers. Integer move instructions can be used to move the values.\n\
6258	\n\
6259	On some machines, though, the converse is true: fixed-point machine\n\
6260	modes may not go in floating registers. This is true if the floating\n\
6261	registers normalize any value stored in them, because storing a\n\
6262	non-floating value there would garble it. In this case,\n\
6263	@code{TARGET_HARD_REGNO_MODE_OK} should reject fixed-point machine modes in\n\
6264	floating registers. But if the floating registers do not automatically\n\
6265	normalize, if you can store any bit pattern in one and retrieve it\n\
6266	unchanged without a trap, then any machine mode may go in a floating\n\
6267	register, so you can define this hook to say so.\n\
6268	\n\
6269	The primary significance of special floating registers is rather that\n\
6270	they are the registers acceptable in floating point arithmetic\n\
6271	instructions. However, this is of no concern to\n\
6272	@code{TARGET_HARD_REGNO_MODE_OK}. You handle it by writing the proper\n\
6273	constraints for those instructions.\n\
6274	\n\
6275	On some machines, the floating registers are especially slow to access,\n\
6276	so that it is better to store a value in a stack frame than in such a\n\
6277	register if floating point arithmetic is not being done. As long as the\n\
6278	floating registers are not in class @code{GENERAL_REGS}, they will not\n\
6279	be used unless some pattern's constraint asks for one.",
6280	bool, (unsigned int regno, machine_mode mode),
6281	hook_bool_uint_mode_true)
6282
6283	DEFHOOK
6284	(modes_tieable_p,
6285	"This hook returns true if a value of mode @var{mode1} is accessible\n\
6286	in mode @var{mode2} without copying.\n\
6287	\n\
6288	If @code{TARGET_HARD_REGNO_MODE_OK (@var{r}, @var{mode1})} and\n\
6289	@code{TARGET_HARD_REGNO_MODE_OK (@var{r}, @var{mode2})} are always\n\
6290	the same for any @var{r}, then\n\
6291	@code{TARGET_MODES_TIEABLE_P (@var{mode1}, @var{mode2})}\n\
6292	should be true. If they differ for any @var{r}, you should define\n\
6293	this hook to return false unless some other mechanism ensures the\n\
6294	accessibility of the value in a narrower mode.\n\
6295	\n\
6296	You should define this hook to return true in as many cases as\n\
6297	possible since doing so will allow GCC to perform better register\n\
6298	allocation. The default definition returns true unconditionally.",
6299	bool, (machine_mode mode1, machine_mode mode2),
6300	hook_bool_mode_mode_true)
6301
6302	/* Return true if is OK to use a hard register REGNO as scratch register
6303	in peephole2. */
6304	DEFHOOK
6305	(hard_regno_scratch_ok,
6306	"This target hook should return @code{true} if it is OK to use a hard register\n\
6307	@var{regno} as scratch reg in peephole2.\n\
6308	\n\
6309	One common use of this macro is to prevent using of a register that\n\
6310	is not saved by a prologue in an interrupt handler.\n\
6311	\n\
6312	The default version of this hook always returns @code{true}.",
6313	bool, (unsigned int regno),
6314	default_hard_regno_scratch_ok)
6315
6316	DEFHOOK
6317	(hard_regno_call_part_clobbered,
6318	"ABIs usually specify that calls must preserve the full contents\n\
6319	of a particular register, or that calls can alter any part of a\n\
6320	particular register. This information is captured by the target macro\n\
6321	@code{CALL_REALLY_USED_REGISTERS}. However, some ABIs specify that calls\n\
6322	must preserve certain bits of a particular register but can alter others.\n\
6323	This hook should return true if this applies to at least one of the\n\
6324	registers in @samp{(reg:@var{mode} @var{regno})}, and if as a result the\n\
6325	call would alter part of the @var{mode} value. For example, if a call\n\
6326	preserves the low 32 bits of a 64-bit hard register @var{regno} but can\n\
6327	clobber the upper 32 bits, this hook should return true for a 64-bit mode\n\
6328	but false for a 32-bit mode.\n\
6329	\n\
6330	The value of @var{abi_id} comes from the @code{predefined_function_abi}\n\
6331	structure that describes the ABI of the call; see the definition of the\n\
6332	structure for more details. If (as is usual) the target uses the same ABI\n\
6333	for all functions in a translation unit, @var{abi_id} is always 0.\n\
6334	\n\
6335	The default implementation returns false, which is correct\n\
6336	for targets that don't have partly call-clobbered registers.",
6337	bool, (unsigned int abi_id, unsigned int regno, machine_mode mode),
6338	hook_bool_uint_uint_mode_false)
6339
6340	DEFHOOK
6341	(get_multilib_abi_name,
6342	"This hook returns name of multilib ABI name.",
6343	const char *, (void),
6344	hook_constcharptr_void_null)
6345
6346	/* Return the smallest number of different values for which it is best to
6347	use a jump-table instead of a tree of conditional branches. */
6348	DEFHOOK
6349	(case_values_threshold,
6350	"This function return the smallest number of different values for which it\n\
6351	is best to use a jump-table instead of a tree of conditional branches.\n\
6352	The default is four for machines with a @code{casesi} instruction and\n\
6353	five otherwise. This is best for most machines.",
6354	unsigned int, (void),
6355	default_case_values_threshold)
6356
6357	DEFHOOK
6358	(starting_frame_offset,
6359	"This hook returns the offset from the frame pointer to the first local\n\
6360	variable slot to be allocated. If @code{FRAME_GROWS_DOWNWARD}, it is the\n\
6361	offset to @emph{end} of the first slot allocated, otherwise it is the\n\
6362	offset to @emph{beginning} of the first slot allocated. The default\n\
6363	implementation returns 0.",
6364	HOST_WIDE_INT, (void),
6365	hook_hwi_void_0)
6366
6367	/* Optional callback to advise the target to compute the frame layout. */
6368	DEFHOOK
6369	(compute_frame_layout,
6370	"This target hook is called once each time the frame layout needs to be\n\
6371	recalculated. The calculations can be cached by the target and can then\n\
6372	be used by @code{INITIAL_ELIMINATION_OFFSET} instead of re-computing the\n\
6373	layout on every invocation of that hook. This is particularly useful\n\
6374	for targets that have an expensive frame layout function. Implementing\n\
6375	this callback is optional.",
6376	void, (void),
6377	hook_void_void)
6378
6379	/* Return true if a function must have and use a frame pointer. */
6380	DEFHOOK
6381	(frame_pointer_required,
6382	"This target hook should return @code{true} if a function must have and use\n\
6383	a frame pointer. This target hook is called in the reload pass. If its return\n\
6384	value is @code{true} the function will have a frame pointer.\n\
6385	\n\
6386	This target hook can in principle examine the current function and decide\n\
6387	according to the facts, but on most machines the constant @code{false} or the\n\
6388	constant @code{true} suffices. Use @code{false} when the machine allows code\n\
6389	to be generated with no frame pointer, and doing so saves some time or space.\n\
6390	Use @code{true} when there is no possible advantage to avoiding a frame\n\
6391	pointer.\n\
6392	\n\
6393	In certain cases, the compiler does not know how to produce valid code\n\
6394	without a frame pointer. The compiler recognizes those cases and\n\
6395	automatically gives the function a frame pointer regardless of what\n\
6396	@code{targetm.frame_pointer_required} returns. You don't need to worry about\n\
6397	them.\n\
6398	\n\
6399	In a function that does not require a frame pointer, the frame pointer\n\
6400	register can be allocated for ordinary usage, unless you mark it as a\n\
6401	fixed register. See @code{FIXED_REGISTERS} for more information.\n\
6402	\n\
6403	Default return value is @code{false}.",
6404	bool, (void),
6405	hook_bool_void_false)
6406
6407	/* Returns true if the compiler is allowed to try to replace register number
6408	from-reg with register number to-reg. */
6409	DEFHOOK
6410	(can_eliminate,
6411	"This target hook should return @code{true} if the compiler is allowed to\n\
6412	try to replace register number @var{from_reg} with register number\n\
6413	@var{to_reg}. This target hook will usually be @code{true}, since most of the\n\
6414	cases preventing register elimination are things that the compiler already\n\
6415	knows about.\n\
6416	\n\
6417	Default return value is @code{true}.",
6418	bool, (const int from_reg, const int to_reg),
6419	hook_bool_const_int_const_int_true)
6420
6421	/* Modify any or all of fixed_regs, call_used_regs, global_regs,
6422	reg_names, and reg_class_contents to account of the vagaries of the
6423	target. */
6424	DEFHOOK
6425	(conditional_register_usage,
6426	"This hook may conditionally modify five variables\n\
6427	@code{fixed_regs}, @code{call_used_regs}, @code{global_regs},\n\
6428	@code{reg_names}, and @code{reg_class_contents}, to take into account\n\
6429	any dependence of these register sets on target flags. The first three\n\
6430	of these are of type @code{char []} (interpreted as boolean vectors).\n\
6431	@code{global_regs} is a @code{const char *[]}, and\n\
6432	@code{reg_class_contents} is a @code{HARD_REG_SET}. Before the macro is\n\
6433	called, @code{fixed_regs}, @code{call_used_regs},\n\
6434	@code{reg_class_contents}, and @code{reg_names} have been initialized\n\
6435	from @code{FIXED_REGISTERS}, @code{CALL_USED_REGISTERS},\n\
6436	@code{REG_CLASS_CONTENTS}, and @code{REGISTER_NAMES}, respectively.\n\
6437	@code{global_regs} has been cleared, and any @option{-ffixed-@var{reg}},\n\
6438	@option{-fcall-used-@var{reg}} and @option{-fcall-saved-@var{reg}}\n\
6439	command options have been applied.\n\
6440	\n\
6441	@cindex disabling certain registers\n\
6442	@cindex controlling register usage\n\
6443	If the usage of an entire class of registers depends on the target\n\
6444	flags, you may indicate this to GCC by using this macro to modify\n\
6445	@code{fixed_regs} and @code{call_used_regs} to 1 for each of the\n\
6446	registers in the classes which should not be used by GCC@. Also make\n\
6447	@code{define_register_constraint}s return @code{NO_REGS} for constraints\n\
6448	that shouldn't be used.\n\
6449	\n\
6450	(However, if this class is not included in @code{GENERAL_REGS} and all\n\
6451	of the insn patterns whose constraints permit this class are\n\
6452	controlled by target switches, then GCC will automatically avoid using\n\
6453	these registers when the target switches are opposed to them.)",
6454	void, (void),
6455	hook_void_void)
6456
6457	DEFHOOK
6458	(stack_clash_protection_alloca_probe_range,
6459	"Some targets have an ABI defined interval for which no probing needs to be done.\n\
6460	When a probe does need to be done this same interval is used as the probe distance\n\
6461	up when doing stack clash protection for alloca.\n\
6462	On such targets this value can be set to override the default probing up interval.\n\
6463	Define this variable to return nonzero if such a probe range is required or zero otherwise.\n\
6464	Defining this hook also requires your functions which make use of alloca to have at least 8 byes\n\
6465	of outgoing arguments. If this is not the case the stack will be corrupted.\n\
6466	You need not define this macro if it would always have the value zero.",
6467	HOST_WIDE_INT, (void),
6468	default_stack_clash_protection_alloca_probe_range)
6469
6470
6471	/* Functions specific to the C family of frontends. */
6472	#undef HOOK_PREFIX
6473	#define HOOK_PREFIX "TARGET_C_"
6474	HOOK_VECTOR (TARGET_C, c)
6475
6476	/* ??? Documenting this hook requires a GFDL license grant. */
6477	DEFHOOK_UNDOC
6478	(mode_for_suffix,
6479	"Return machine mode for non-standard constant literal suffix @var{c},\
6480	or VOIDmode if non-standard suffixes are unsupported.",
6481	machine_mode, (char c),
6482	default_mode_for_suffix)
6483
6484	DEFHOOK
6485	(excess_precision,
6486	"Return a value, with the same meaning as the C99 macro\n\
6487	@code{FLT_EVAL_METHOD} that describes which excess precision should be\n\
6488	applied. @var{type} is either @code{EXCESS_PRECISION_TYPE_IMPLICIT},\n\
6489	@code{EXCESS_PRECISION_TYPE_FAST},\n\
6490	@code{EXCESS_PRECISION_TYPE_STANDARD}, or\n\
6491	@code{EXCESS_PRECISION_TYPE_FLOAT16}. For\n\
6492	@code{EXCESS_PRECISION_TYPE_IMPLICIT}, the target should return which\n\
6493	precision and range operations will be implictly evaluated in regardless\n\
6494	of the excess precision explicitly added. For\n\
6495	@code{EXCESS_PRECISION_TYPE_STANDARD}, \n\
6496	@code{EXCESS_PRECISION_TYPE_FLOAT16}, and\n\
6497	@code{EXCESS_PRECISION_TYPE_FAST}, the target should return the\n\
6498	explicit excess precision that should be added depending on the\n\
6499	value set for @option{-fexcess-precision=@r{[}standard@r{|}fast@r{|}16@r{]}}.\n\
6500	Note that unpredictable explicit excess precision does not make sense,\n\
6501	so a target should never return @code{FLT_EVAL_METHOD_UNPREDICTABLE}\n\
6502	when @var{type} is @code{EXCESS_PRECISION_TYPE_STANDARD},\n\
6503	@code{EXCESS_PRECISION_TYPE_FLOAT16} or\n\
6504	@code{EXCESS_PRECISION_TYPE_FAST}.",
6505	enum flt_eval_method, (enum excess_precision_type type),
6506	default_excess_precision)
6507
6508	/* Return true if _BitInt(N) is supported and fill details about it into
6509	*INFO. */
6510	DEFHOOK
6511	(bitint_type_info,
6512	"This target hook returns true if @code{_BitInt(@var{N})} is supported and\n\
6513	provides details on it. @code{_BitInt(@var{N})} is to be represented as\n\
6514	series of @code{info->abi_limb_mode}\n\
6515	@code{CEIL (@var{N}, GET_MODE_PRECISION (info->abi_limb_mode))} limbs,\n\
6516	ordered from least significant to most significant if\n\
6517	@code{!info->big_endian}, otherwise from most significant to least\n\
6518	significant. If @code{info->extended} is false, the bits above or equal to\n\
6519	@var{N} are undefined when stored in a register or memory, otherwise they\n\
6520	are zero or sign extended depending on if it is\n\
6521	@code{unsigned _BitInt(@var{N})} or one of @code{_BitInt(@var{N})} or\n\
6522	@code{signed _BitInt(@var{N})}. Alignment of the type is\n\
6523	@code{GET_MODE_ALIGNMENT (info->limb_mode)}.",
6524	bool, (int n, struct bitint_info *info),
6525	default_bitint_type_info)
6526
6527	DEFHOOK
6528	(mode_for_floating_type,
6529	"Return machine mode for a C floating point type which is indicated by\n\
6530	a given @code{enum tree_index} @var{ti}, @var{ti} should be\n\
6531	@code{TI_FLOAT_TYPE}, @code{TI_DOUBLE_TYPE} or @code{TI_LONG_DOUBLE_TYPE}.\n\
6532	The default implementation returns @code{SFmode} for @code{TI_FLOAT_TYPE},\n\
6533	and @code{DFmode} for @code{TI_DOUBLE_TYPE} or @code{TI_LONG_DOUBLE_TYPE}.",
6534	machine_mode, (enum tree_index ti), default_mode_for_floating_type)
6535
6536	HOOK_VECTOR_END (c)
6537
6538	/* Functions specific to the C++ frontend. */
6539	#undef HOOK_PREFIX
6540	#define HOOK_PREFIX "TARGET_CXX_"
6541	HOOK_VECTOR (TARGET_CXX, cxx)
6542
6543	/* Return the integer type used for guard variables. */
6544	DEFHOOK
6545	(guard_type,
6546	"Define this hook to override the integer type used for guard variables.\n\
6547	These are used to implement one-time construction of static objects. The\n\
6548	default is long_long_integer_type_node.",
6549	tree, (void),
6550	default_cxx_guard_type)
6551
6552	/* Return true if only the low bit of the guard should be tested. */
6553	DEFHOOK
6554	(guard_mask_bit,
6555	"This hook determines how guard variables are used. It should return\n\
6556	@code{false} (the default) if the first byte should be used. A return value of\n\
6557	@code{true} indicates that only the least significant bit should be used.",
6558	bool, (void),
6559	hook_bool_void_false)
6560
6561	/* Returns the size of the array cookie for an array of type. */
6562	DEFHOOK
6563	(get_cookie_size,
6564	"This hook returns the size of the cookie to use when allocating an array\n\
6565	whose elements have the indicated @var{type}. Assumes that it is already\n\
6566	known that a cookie is needed. The default is\n\
6567	@code{max(sizeof (size_t), alignof(type))}, as defined in section 2.7 of the\n\
6568	IA64/Generic C++ ABI@.",
6569	tree, (tree type),
6570	default_cxx_get_cookie_size)
6571
6572	/* Returns true if the element size should be stored in the array cookie. */
6573	DEFHOOK
6574	(cookie_has_size,
6575	"This hook should return @code{true} if the element size should be stored in\n\
6576	array cookies. The default is to return @code{false}.",
6577	bool, (void),
6578	hook_bool_void_false)
6579
6580	/* Allows backends to perform additional processing when
6581	deciding if a class should be exported or imported. */
6582	DEFHOOK
6583	(import_export_class,
6584	"If defined by a backend this hook allows the decision made to export\n\
6585	class @var{type} to be overruled. Upon entry @var{import_export}\n\
6586	will contain 1 if the class is going to be exported, @minus{}1 if it is going\n\
6587	to be imported and 0 otherwise. This function should return the\n\
6588	modified value and perform any other actions necessary to support the\n\
6589	backend's targeted operating system.",
6590	int, (tree type, int import_export), NULL)
6591
6592	/* Returns true if constructors and destructors return "this". */
6593	DEFHOOK
6594	(cdtor_returns_this,
6595	"This hook should return @code{true} if constructors and destructors return\n\
6596	the address of the object created/destroyed. The default is to return\n\
6597	@code{false}.",
6598	bool, (void),
6599	hook_bool_void_false)
6600
6601	/* Returns true if the key method for a class can be an inline
6602	function, so long as it is not declared inline in the class
6603	itself. Returning true is the behavior required by the Itanium C++ ABI. */
6604	DEFHOOK
6605	(key_method_may_be_inline,
6606	"This hook returns true if the key method for a class (i.e., the method\n\
6607	which, if defined in the current translation unit, causes the virtual\n\
6608	table to be emitted) may be an inline function. Under the standard\n\
6609	Itanium C++ ABI the key method may be an inline function so long as\n\
6610	the function is not declared inline in the class definition. Under\n\
6611	some variants of the ABI, an inline function can never be the key\n\
6612	method. The default is to return @code{true}.",
6613	bool, (void),
6614	hook_bool_void_true)
6615
6616	DEFHOOK
6617	(determine_class_data_visibility,
6618	"@var{decl} is a virtual table, virtual table table, typeinfo object,\n\
6619	or other similar implicit class data object that will be emitted with\n\
6620	external linkage in this translation unit. No ELF visibility has been\n\
6621	explicitly specified. If the target needs to specify a visibility\n\
6622	other than that of the containing class, use this hook to set\n\
6623	@code{DECL_VISIBILITY} and @code{DECL_VISIBILITY_SPECIFIED}.",
6624	void, (tree decl),
6625	hook_void_tree)
6626
6627	/* Returns true (the default) if virtual tables and other
6628	similar implicit class data objects are always COMDAT if they
6629	have external linkage. If this hook returns false, then
6630	class data for classes whose virtual table will be emitted in
6631	only one translation unit will not be COMDAT. */
6632	DEFHOOK
6633	(class_data_always_comdat,
6634	"This hook returns true (the default) if virtual tables and other\n\
6635	similar implicit class data objects are always COMDAT if they have\n\
6636	external linkage. If this hook returns false, then class data for\n\
6637	classes whose virtual table will be emitted in only one translation\n\
6638	unit will not be COMDAT.",
6639	bool, (void),
6640	hook_bool_void_true)
6641
6642	/* Returns true (the default) if the RTTI for the basic types,
6643	which is always defined in the C++ runtime, should be COMDAT;
6644	false if it should not be COMDAT. */
6645	DEFHOOK
6646	(library_rtti_comdat,
6647	"This hook returns true (the default) if the RTTI information for\n\
6648	the basic types which is defined in the C++ runtime should always\n\
6649	be COMDAT, false if it should not be COMDAT.",
6650	bool, (void),
6651	hook_bool_void_true)
6652
6653	/* Returns true if __aeabi_atexit should be used to register static
6654	destructors. */
6655	DEFHOOK
6656	(use_aeabi_atexit,
6657	"This hook returns true if @code{__aeabi_atexit} (as defined by the ARM EABI)\n\
6658	should be used to register static destructors when @option{-fuse-cxa-atexit}\n\
6659	is in effect. The default is to return false to use @code{__cxa_atexit}.",
6660	bool, (void),
6661	hook_bool_void_false)
6662
6663	/* Returns true if target may use atexit in the same manner as
6664	__cxa_atexit to register static destructors. */
6665	DEFHOOK
6666	(use_atexit_for_cxa_atexit,
6667	"This hook returns true if the target @code{atexit} function can be used\n\
6668	in the same manner as @code{__cxa_atexit} to register C++ static\n\
6669	destructors. This requires that @code{atexit}-registered functions in\n\
6670	shared libraries are run in the correct order when the libraries are\n\
6671	unloaded. The default is to return false.",
6672	bool, (void),
6673	hook_bool_void_false)
6674
6675	/* Returns modified FUNCTION_TYPE for cdtor callabi. */
6676	DEFHOOK
6677	(adjust_cdtor_callabi_fntype,
6678	"This hook returns a possibly modified @code{FUNCTION_TYPE} for arguments\n\
6679	to @code{__cxa_atexit}, @code{__cxa_thread_atexit} or @code{__cxa_throw}\n\
6680	function pointers. ABIs like mingw32 require special attributes to be added\n\
6681	to function types pointed to by arguments of these functions.\n\
6682	The default is to return the passed argument unmodified.",
6683	tree, (tree fntype),
6684	default_cxx_adjust_cdtor_callabi_fntype)
6685
6686	DEFHOOK
6687	(adjust_class_at_definition,
6688	"@var{type} is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just\n\
6689	been defined. Use this hook to make adjustments to the class (eg, tweak\n\
6690	visibility or perform any other required target modifications).",
6691	void, (tree type),
6692	hook_void_tree)
6693
6694	DEFHOOK
6695	(decl_mangling_context,
6696	"Return target-specific mangling context of @var{decl} or @code{NULL_TREE}.",
6697	tree, (const_tree decl),
6698	hook_tree_const_tree_null)
6699
6700	HOOK_VECTOR_END (cxx)
6701
6702	/* Functions and data for emulated TLS support. */
6703	#undef HOOK_PREFIX
6704	#define HOOK_PREFIX "TARGET_EMUTLS_"
6705	HOOK_VECTOR (TARGET_EMUTLS, emutls)
6706
6707	/* Name of the address and common functions. */
6708	DEFHOOKPOD
6709	(get_address,
6710	"Contains the name of the helper function that uses a TLS control\n\
6711	object to locate a TLS instance. The default causes libgcc's\n\
6712	emulated TLS helper function to be used.",
6713	const char *, "__builtin___emutls_get_address")
6714
6715	DEFHOOKPOD
6716	(register_common,
6717	"Contains the name of the helper function that should be used at\n\
6718	program startup to register TLS objects that are implicitly\n\
6719	initialized to zero. If this is @code{NULL}, all TLS objects will\n\
6720	have explicit initializers. The default causes libgcc's emulated TLS\n\
6721	registration function to be used.",
6722	const char *, "__builtin___emutls_register_common")
6723
6724	/* Prefixes for proxy variable and template. */
6725	DEFHOOKPOD
6726	(var_section,
6727	"Contains the name of the section in which TLS control variables should\n\
6728	be placed. The default of @code{NULL} allows these to be placed in\n\
6729	any section.",
6730	const char *, NULL)
6731
6732	DEFHOOKPOD
6733	(tmpl_section,
6734	"Contains the name of the section in which TLS initializers should be\n\
6735	placed. The default of @code{NULL} allows these to be placed in any\n\
6736	section.",
6737	const char *, NULL)
6738
6739	/* Prefixes for proxy variable and template. */
6740	DEFHOOKPOD
6741	(var_prefix,
6742	"Contains the prefix to be prepended to TLS control variable names.\n\
6743	The default of @code{NULL} uses a target-specific prefix.",
6744	const char *, NULL)
6745
6746	DEFHOOKPOD
6747	(tmpl_prefix,
6748	"Contains the prefix to be prepended to TLS initializer objects. The\n\
6749	default of @code{NULL} uses a target-specific prefix.",
6750	const char *, NULL)
6751
6752	/* Function to generate field definitions of the proxy variable. */
6753	DEFHOOK
6754	(var_fields,
6755	"Specifies a function that generates the FIELD_DECLs for a TLS control\n\
6756	object type. @var{type} is the RECORD_TYPE the fields are for and\n\
6757	@var{name} should be filled with the structure tag, if the default of\n\
6758	@code{__emutls_object} is unsuitable. The default creates a type suitable\n\
6759	for libgcc's emulated TLS function.",
6760	tree, (tree type, tree *name),
6761	default_emutls_var_fields)
6762
6763	/* Function to initialize a proxy variable. */
6764	DEFHOOK
6765	(var_init,
6766	"Specifies a function that generates the CONSTRUCTOR to initialize a\n\
6767	TLS control object. @var{var} is the TLS control object, @var{decl}\n\
6768	is the TLS object and @var{tmpl_addr} is the address of the\n\
6769	initializer. The default initializes libgcc's emulated TLS control object.",
6770	tree, (tree var, tree decl, tree tmpl_addr),
6771	default_emutls_var_init)
6772
6773	/* Whether we are allowed to alter the usual alignment of the
6774	proxy variable. */
6775	DEFHOOKPOD
6776	(var_align_fixed,
6777	"Specifies whether the alignment of TLS control variable objects is\n\
6778	fixed and should not be increased as some backends may do to optimize\n\
6779	single objects. The default is false.",
6780	bool, false)
6781
6782	/* Whether we can emit debug information for TLS vars. */
6783	DEFHOOKPOD
6784	(debug_form_tls_address,
6785	"Specifies whether a DWARF @code{DW_OP_form_tls_address} location descriptor\n\
6786	may be used to describe emulated TLS control objects.",
6787	bool, false)
6788
6789	HOOK_VECTOR_END (emutls)
6790
6791	#undef HOOK_PREFIX
6792	#define HOOK_PREFIX "TARGET_OPTION_"
6793	HOOK_VECTOR (TARGET_OPTION_HOOKS, target_option_hooks)
6794
6795	/* Function to validate the attribute((target(...))) strings. If
6796	the option is validated, the hook should also fill in
6797	DECL_FUNCTION_SPECIFIC_TARGET in the function decl node. */
6798	DEFHOOK
6799	(valid_attribute_p,
6800	"This hook is called to parse @code{attribute(target(\"...\"))}, which\n\
6801	allows setting target-specific options on individual functions.\n\
6802	These function-specific options may differ\n\
6803	from the options specified on the command line. The hook should return\n\
6804	@code{true} if the options are valid.\n\
6805	\n\
6806	The hook should set the @code{DECL_FUNCTION_SPECIFIC_TARGET} field in\n\
6807	the function declaration to hold a pointer to a target-specific\n\
6808	@code{struct cl_target_option} structure.",
6809	bool, (tree fndecl, tree name, tree args, int flags),
6810	default_target_option_valid_attribute_p)
6811
6812	/* Function to validate the attribute((target_version(...))) strings. If
6813	the option is validated, the hook should also fill in
6814	DECL_FUNCTION_SPECIFIC_TARGET in the function decl node. */
6815	DEFHOOK
6816	(valid_version_attribute_p,
6817	"This hook is called to parse @code{attribute(target_version(\"...\"))},\n\
6818	which allows setting target-specific options on individual function versions.\n\
6819	These function-specific options may differ\n\
6820	from the options specified on the command line. The hook should return\n\
6821	@code{true} if the options are valid.\n\
6822	\n\
6823	The hook should set the @code{DECL_FUNCTION_SPECIFIC_TARGET} field in\n\
6824	the function declaration to hold a pointer to a target-specific\n\
6825	@code{struct cl_target_option} structure.",
6826	bool, (tree fndecl, tree name, tree args, int flags),
6827	default_target_option_valid_version_attribute_p)
6828
6829	/* Function to save any extra target state in the target options structure. */
6830	DEFHOOK
6831	(save,
6832	"This hook is called to save any additional target-specific information\n\
6833	in the @code{struct cl_target_option} structure for function-specific\n\
6834	options from the @code{struct gcc_options} structure.\n\
6835	@xref{Option file format}.",
6836	void, (struct cl_target_option *ptr, struct gcc_options *opts,
6837	struct gcc_options *opts_set), NULL)
6838
6839	/* Function to restore any extra target state from the target options
6840	structure. */
6841	DEFHOOK
6842	(restore,
6843	"This hook is called to restore any additional target-specific\n\
6844	information in the @code{struct cl_target_option} structure for\n\
6845	function-specific options to the @code{struct gcc_options} structure.",
6846	void, (struct gcc_options *opts, struct gcc_options *opts_set,
6847	struct cl_target_option *ptr), NULL)
6848
6849	/* Function to update target-specific option information after being
6850	streamed in. */
6851	DEFHOOK
6852	(post_stream_in,
6853	"This hook is called to update target-specific information in the\n\
6854	@code{struct cl_target_option} structure after it is streamed in from\n\
6855	LTO bytecode.",
6856	void, (struct cl_target_option *ptr), NULL)
6857
6858	/* Function to print any extra target state from the target options
6859	structure. */
6860	DEFHOOK
6861	(print,
6862	"This hook is called to print any additional target-specific\n\
6863	information in the @code{struct cl_target_option} structure for\n\
6864	function-specific options.",
6865	void, (FILE *file, int indent, struct cl_target_option *ptr), NULL)
6866
6867	/* Function to parse arguments to be validated for #pragma target, and to
6868	change the state if the options are valid. If the first argument is
6869	NULL, the second argument specifies the default options to use. Return
6870	true if the options are valid, and set the current state. */
6871	DEFHOOK
6872	(pragma_parse,
6873	"This target hook parses the options for @code{#pragma GCC target}, which\n\
6874	sets the target-specific options for functions that occur later in the\n\
6875	input stream. The options accepted should be the same as those handled by the\n\
6876	@code{TARGET_OPTION_VALID_ATTRIBUTE_P} hook.",
6877	bool, (tree args, tree pop_target),
6878	default_target_option_pragma_parse)
6879
6880	/* Do option overrides for the target. */
6881	DEFHOOK
6882	(override,
6883	"Sometimes certain combinations of command options do not make sense on\n\
6884	a particular target machine. You can override the hook\n\
6885	@code{TARGET_OPTION_OVERRIDE} to take account of this. This hooks is called\n\
6886	once just after all the command options have been parsed.\n\
6887	\n\
6888	Don't use this hook to turn on various extra optimizations for\n\
6889	@option{-O}. That is what @code{TARGET_OPTION_OPTIMIZATION} is for.\n\
6890	\n\
6891	If you need to do something whenever the optimization level is\n\
6892	changed via the optimize attribute or pragma, see\n\
6893	@code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}",
6894	void, (void),
6895	hook_void_void)
6896
6897	/* This function returns true if DECL1 and DECL2 are versions of the same
6898	function. DECL1 and DECL2 are function versions if and only if they
6899	have the same function signature and different target specific attributes,
6900	that is, they are compiled for different target machines. */
6901	DEFHOOK
6902	(function_versions,
6903	"This target hook returns @code{true} if @var{DECL1} and @var{DECL2} are\n\
6904	versions of the same function. @var{DECL1} and @var{DECL2} are function\n\
6905	versions if and only if they have the same function signature and\n\
6906	different target specific attributes, that is, they are compiled for\n\
6907	different target machines.",
6908	bool, (tree decl1, tree decl2),
6909	hook_bool_tree_tree_false)
6910
6911	/* Function to determine if one function can inline another function. */
6912	#undef HOOK_PREFIX
6913	#define HOOK_PREFIX "TARGET_"
6914	DEFHOOK
6915	(can_inline_p,
6916	"This target hook returns @code{false} if the @var{caller} function\n\
6917	cannot inline @var{callee}, based on target specific information. By\n\
6918	default, inlining is not allowed if the callee function has function\n\
6919	specific target options and the caller does not use the same options.",
6920	bool, (tree caller, tree callee),
6921	default_target_can_inline_p)
6922
6923	DEFHOOK
6924	(update_ipa_fn_target_info,
6925	"Allow target to analyze all gimple statements for the given function to\n\
6926	record and update some target specific information for inlining. A typical\n\
6927	example is that a caller with one isa feature disabled is normally not\n\
6928	allowed to inline a callee with that same isa feature enabled even which is\n\
6929	attributed by always_inline, but with the conservative analysis on all\n\
6930	statements of the callee if we are able to guarantee the callee does not\n\
6931	exploit any instructions from the mismatch isa feature, it would be safe to\n\
6932	allow the caller to inline the callee.\n\
6933	@var{info} is one @code{unsigned int} value to record information in which\n\
6934	one set bit indicates one corresponding feature is detected in the analysis,\n\
6935	@var{stmt} is the statement being analyzed. Return true if target still\n\
6936	need to analyze the subsequent statements, otherwise return false to stop\n\
6937	subsequent analysis.\n\
6938	The default version of this hook returns false.",
6939	bool, (unsigned int& info, const gimple* stmt),
6940	default_update_ipa_fn_target_info)
6941
6942	DEFHOOK
6943	(need_ipa_fn_target_info,
6944	"Allow target to check early whether it is necessary to analyze all gimple\n\
6945	statements in the given function to update target specific information for\n\
6946	inlining. See hook @code{update_ipa_fn_target_info} for usage example of\n\
6947	target specific information. This hook is expected to be invoked ahead of\n\
6948	the iterating with hook @code{update_ipa_fn_target_info}.\n\
6949	@var{decl} is the function being analyzed, @var{info} is the same as what\n\
6950	in hook @code{update_ipa_fn_target_info}, target can do one time update\n\
6951	into @var{info} without iterating for some case. Return true if target\n\
6952	decides to analyze all gimple statements to collect information, otherwise\n\
6953	return false.\n\
6954	The default version of this hook returns false.",
6955	bool, (const_tree decl, unsigned int& info),
6956	default_need_ipa_fn_target_info)
6957
6958	DEFHOOK
6959	(relayout_function,
6960	"This target hook fixes function @var{fndecl} after attributes are processed.\n\
6961	Default does nothing. On ARM, the default function's alignment is updated\n\
6962	with the attribute target.",
6963	void, (tree fndecl),
6964	hook_void_tree)
6965
6966	HOOK_VECTOR_END (target_option)
6967
6968	/* For targets that need to mark extra registers as live on entry to
6969	the function, they should define this target hook and set their
6970	bits in the bitmap passed in. */
6971	DEFHOOK
6972	(extra_live_on_entry,
6973	"Add any hard registers to @var{regs} that are live on entry to the\n\
6974	function. This hook only needs to be defined to provide registers that\n\
6975	cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved\n\
6976	registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,\n\
6977	TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,\n\
6978	FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.",
6979	void, (bitmap regs),
6980	hook_void_bitmap)
6981
6982	/* Targets should define this target hook to mark that non-callee clobbers are
6983	present in CALL_INSN_FUNCTION_USAGE for all the calls that bind to a local
6984	definition. */
6985	DEFHOOKPOD
6986	(call_fusage_contains_non_callee_clobbers,
6987	"Set to true if each call that binds to a local definition explicitly\n\
6988	clobbers or sets all non-fixed registers modified by performing the call.\n\
6989	That is, by the call pattern itself, or by code that might be inserted by the\n\
6990	linker (e.g.@: stubs, veneers, branch islands), but not including those\n\
6991	modifiable by the callee. The affected registers may be mentioned explicitly\n\
6992	in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.\n\
6993	The default version of this hook is set to false. The purpose of this hook\n\
6994	is to enable the fipa-ra optimization.",
6995	bool,
6996	false)
6997
6998	/* Fill in additional registers set up by prologue into a regset. */
6999	DEFHOOK
7000	(set_up_by_prologue,
7001	"This hook should add additional registers that are computed by the prologue\n\
7002	to the hard regset for shrink-wrapping optimization purposes.",
7003	void, (struct hard_reg_set_container *),
7004	NULL)
7005
7006	/* For targets that have attributes that can affect whether a
7007	function's return statements need checking. For instance a 'naked'
7008	function attribute. */
7009	DEFHOOK
7010	(warn_func_return,
7011	"True if a function's return statements should be checked for matching\n\
7012	the function's return type. This includes checking for falling off the end\n\
7013	of a non-void function. Return false if no such check should be made.",
7014	bool, (tree),
7015	hook_bool_tree_true)
7016
7017	#undef HOOK_PREFIX
7018	#define HOOK_PREFIX "TARGET_SHRINK_WRAP_"
7019	HOOK_VECTOR (TARGET_SHRINK_WRAP_HOOKS, shrink_wrap)
7020
7021	DEFHOOK
7022	(get_separate_components,
7023	"This hook should return an @code{sbitmap} with the bits set for those\n\
7024	components that can be separately shrink-wrapped in the current function.\n\
7025	Return @code{NULL} if the current function should not get any separate\n\
7026	shrink-wrapping.\n\
7027	Don't define this hook if it would always return @code{NULL}.\n\
7028	If it is defined, the other hooks in this group have to be defined as well.",
7029	sbitmap, (void),
7030	NULL)
7031
7032	DEFHOOK
7033	(components_for_bb,
7034	"This hook should return an @code{sbitmap} with the bits set for those\n\
7035	components where either the prologue component has to be executed before\n\
7036	the @code{basic_block}, or the epilogue component after it, or both.",
7037	sbitmap, (basic_block),
7038	NULL)
7039
7040	DEFHOOK
7041	(disqualify_components,
7042	"This hook should clear the bits in the @var{components} bitmap for those\n\
7043	components in @var{edge_components} that the target cannot handle on edge\n\
7044	@var{e}, where @var{is_prologue} says if this is for a prologue or an\n\
7045	epilogue instead.",
7046	void, (sbitmap components, edge e, sbitmap edge_components, bool is_prologue),
7047	NULL)
7048
7049	DEFHOOK
7050	(emit_prologue_components,
7051	"Emit prologue insns for the components indicated by the parameter.",
7052	void, (sbitmap),
7053	NULL)
7054
7055	DEFHOOK
7056	(emit_epilogue_components,
7057	"Emit epilogue insns for the components indicated by the parameter.",
7058	void, (sbitmap),
7059	NULL)
7060
7061	DEFHOOK
7062	(set_handled_components,
7063	"Mark the components in the parameter as handled, so that the\n\
7064	@code{prologue} and @code{epilogue} named patterns know to ignore those\n\
7065	components. The target code should not hang on to the @code{sbitmap}, it\n\
7066	will be deleted after this call.",
7067	void, (sbitmap),
7068	NULL)
7069
7070	HOOK_VECTOR_END (shrink_wrap)
7071	#undef HOOK_PREFIX
7072	#define HOOK_PREFIX "TARGET_"
7073
7074	DEFHOOK
7075	(avoid_store_forwarding_p,
7076	"Given a list of stores and a load instruction that reads from the location\n\
7077	of the stores, this hook decides if it's profitable to emit additional code\n\
7078	to avoid a potential store forwarding stall. The additional instructions\n\
7079	needed, the sequence cost and additional relevant information is given in\n\
7080	the arguments so that the target can make an informed decision.",
7081	bool, (vec<store_fwd_info>, rtx, int, bool),
7082	default_avoid_store_forwarding_p)
7083
7084	/* Determine the type of unwind info to emit for debugging. */
7085	DEFHOOK
7086	(debug_unwind_info,
7087	"This hook defines the mechanism that will be used for describing frame\n\
7088	unwind information to the debugger. Normally the hook will return\n\
7089	@code{UI_DWARF2} if DWARF 2 debug information is enabled, and\n\
7090	return @code{UI_NONE} otherwise.\n\
7091	\n\
7092	A target may return @code{UI_DWARF2} even when DWARF 2 debug information\n\
7093	is disabled in order to always output DWARF 2 frame information.\n\
7094	\n\
7095	A target may return @code{UI_TARGET} if it has ABI specified unwind tables.\n\
7096	This will suppress generation of the normal debug frame unwind information.",
7097	enum unwind_info_type, (void),
7098	default_debug_unwind_info)
7099
7100	DEFHOOK
7101	(reset_location_view,
7102	"This hook, if defined, enables -ginternal-reset-location-views, and\n\
7103	uses its result to override cases in which the estimated min insn\n\
7104	length might be nonzero even when a PC advance (i.e., a view reset)\n\
7105	cannot be taken for granted.\n\
7106	\n\
7107	If the hook is defined, it must return a positive value to indicate\n\
7108	the insn definitely advances the PC, and so the view number can be\n\
7109	safely assumed to be reset; a negative value to mean the insn\n\
7110	definitely does not advance the PC, and os the view number must not\n\
7111	be reset; or zero to decide based on the estimated insn length.\n\
7112	\n\
7113	If insn length is to be regarded as reliable, set the hook to\n\
7114	@code{hook_int_rtx_insn_0}.",
7115	int, (rtx_insn *), NULL)
7116
7117	/* The code parameter should be of type enum rtx_code but this is not
7118	defined at this time. */
7119	DEFHOOK
7120	(canonicalize_comparison,
7121	"On some machines not all possible comparisons are defined, but you can\n\
7122	convert an invalid comparison into a valid one. For example, the Alpha\n\
7123	does not have a @code{GT} comparison, but you can use an @code{LT}\n\
7124	comparison instead and swap the order of the operands.\n\
7125	\n\
7126	On such machines, implement this hook to do any required conversions.\n\
7127	@var{code} is the initial comparison code and @var{op0} and @var{op1}\n\
7128	are the left and right operands of the comparison, respectively. If\n\
7129	@var{op0_preserve_value} is @code{true} the implementation is not\n\
7130	allowed to change the value of @var{op0} since the value might be used\n\
7131	in RTXs which aren't comparisons. E.g. the implementation is not\n\
7132	allowed to swap operands in that case.\n\
7133	\n\
7134	GCC will not assume that the comparison resulting from this macro is\n\
7135	valid but will see if the resulting insn matches a pattern in the\n\
7136	@file{md} file.\n\
7137	\n\
7138	You need not to implement this hook if it would never change the\n\
7139	comparison code or operands.",
7140	void, (int *code, rtx *op0, rtx *op1, bool op0_preserve_value),
7141	default_canonicalize_comparison)
7142
7143	DEFHOOK
7144	(min_arithmetic_precision,
7145	"On some RISC architectures with 64-bit registers, the processor also\n\
7146	maintains 32-bit condition codes that make it possible to do real 32-bit\n\
7147	arithmetic, although the operations are performed on the full registers.\n\
7148	\n\
7149	On such architectures, defining this hook to 32 tells the compiler to try\n\
7150	using 32-bit arithmetical operations setting the condition codes instead\n\
7151	of doing full 64-bit arithmetic.\n\
7152	\n\
7153	More generally, define this hook on RISC architectures if you want the\n\
7154	compiler to try using arithmetical operations setting the condition codes\n\
7155	with a precision lower than the word precision.\n\
7156	\n\
7157	You need not define this hook if @code{WORD_REGISTER_OPERATIONS} is not\n\
7158	defined to 1.",
7159	unsigned int, (void), default_min_arithmetic_precision)
7160
7161	DEFHOOKPOD
7162	(atomic_test_and_set_trueval,
7163	"This value should be set if the result written by\n\
7164	@code{atomic_test_and_set} is not exactly 1, i.e.@: the\n\
7165	@code{bool} @code{true}.",
7166	unsigned char, 1)
7167
7168	/* Return an unsigned int representing the alignment (in bits) of the atomic
7169	type which maps to machine MODE. This allows alignment to be overridden
7170	as needed. */
7171	DEFHOOK
7172	(atomic_align_for_mode,
7173	"If defined, this function returns an appropriate alignment in bits for an\n\
7174	atomic object of machine_mode @var{mode}. If 0 is returned then the\n\
7175	default alignment for the specified mode is used.",
7176	unsigned int, (machine_mode mode),
7177	hook_uint_mode_0)
7178
7179	DEFHOOK
7180	(atomic_assign_expand_fenv,
7181	"ISO C11 requires atomic compound assignments that may raise floating-point\n\
7182	exceptions to raise exceptions corresponding to the arithmetic operation\n\
7183	whose result was successfully stored in a compare-and-exchange sequence.\n\
7184	This requires code equivalent to calls to @code{feholdexcept},\n\
7185	@code{feclearexcept} and @code{feupdateenv} to be generated at\n\
7186	appropriate points in the compare-and-exchange sequence. This hook should\n\
7187	set @code{*@var{hold}} to an expression equivalent to the call to\n\
7188	@code{feholdexcept}, @code{*@var{clear}} to an expression equivalent to\n\
7189	the call to @code{feclearexcept} and @code{*@var{update}} to an expression\n\
7190	equivalent to the call to @code{feupdateenv}. The three expressions are\n\
7191	@code{NULL_TREE} on entry to the hook and may be left as @code{NULL_TREE}\n\
7192	if no code is required in a particular place. The default implementation\n\
7193	leaves all three expressions as @code{NULL_TREE}. The\n\
7194	@code{__atomic_feraiseexcept} function from @code{libatomic} may be of use\n\
7195	as part of the code generated in @code{*@var{update}}.",
7196	void, (tree *hold, tree *clear, tree *update),
7197	default_atomic_assign_expand_fenv)
7198
7199	/* Leave the boolean fields at the end. */
7200
7201	/* True if we can create zeroed data by switching to a BSS section
7202	and then using ASM_OUTPUT_SKIP to allocate the space. */
7203	DEFHOOKPOD
7204	(have_switchable_bss_sections,
7205	"This flag is true if we can create zeroed data by switching to a BSS\n\
7206	section and then using @code{ASM_OUTPUT_SKIP} to allocate the space.\n\
7207	This is true on most ELF targets.",
7208	bool, false)
7209
7210	/* True if "native" constructors and destructors are supported,
7211	false if we're using collect2 for the job. */
7212	DEFHOOKPOD
7213	(have_ctors_dtors,
7214	"This value is true if the target supports some ``native'' method of\n\
7215	collecting constructors and destructors to be run at startup and exit.\n\
7216	It is false if we must use @command{collect2}.",
7217	bool, false)
7218
7219	/* True if the target wants DTORs to be run from cxa_atexit. */
7220	DEFHOOKPOD
7221	(dtors_from_cxa_atexit,
7222	"This value is true if the target wants destructors to be queued to be\n\
7223	run from __cxa_atexit. If this is the case then, for each priority level,\n\
7224	a new constructor will be entered that registers the destructors for that\n\
7225	level with __cxa_atexit (and there will be no destructors emitted).\n\
7226	It is false the method implied by @code{have_ctors_dtors} is used.",
7227	bool, false)
7228
7229	/* True if thread-local storage is supported. */
7230	DEFHOOKPOD
7231	(have_tls,
7232	"Contains the value true if the target supports thread-local storage.\n\
7233	The default value is false.",
7234	bool, false)
7235
7236	/* True if a small readonly data section is supported. */
7237	DEFHOOKPOD
7238	(have_srodata_section,
7239	"Contains the value true if the target places read-only\n\
7240	``small data'' into a separate section. The default value is false.",
7241	bool, false)
7242
7243	/* True if EH frame info sections should be zero-terminated. */
7244	DEFHOOKPOD
7245	(terminate_dw2_eh_frame_info,
7246	"Contains the value true if the target should add a zero word onto the\n\
7247	end of a Dwarf-2 frame info section when used for exception handling.\n\
7248	Default value is false if @code{EH_FRAME_SECTION_NAME} is defined, and\n\
7249	true otherwise.",
7250	bool, true)
7251
7252	/* True if #NO_APP should be emitted at the beginning of assembly output. */
7253	DEFHOOKPOD
7254	(asm_file_start_app_off,
7255	"If this flag is true, the text of the macro @code{ASM_APP_OFF} will be\n\
7256	printed as the very first line in the assembly file, unless\n\
7257	@option{-fverbose-asm} is in effect. (If that macro has been defined\n\
7258	to the empty string, this variable has no effect.) With the normal\n\
7259	definition of @code{ASM_APP_OFF}, the effect is to notify the GNU\n\
7260	assembler that it need not bother stripping comments or extra\n\
7261	whitespace from its input. This allows it to work a bit faster.\n\
7262	\n\
7263	The default is false. You should not set it to true unless you have\n\
7264	verified that your port does not generate any extra whitespace or\n\
7265	comments that will cause GAS to issue errors in NO_APP mode.",
7266	bool, false)
7267
7268	/* True if output_file_directive should be called for main_input_filename
7269	at the beginning of assembly output. */
7270	DEFHOOKPOD
7271	(asm_file_start_file_directive,
7272	"If this flag is true, @code{output_file_directive} will be called\n\
7273	for the primary source file, immediately after printing\n\
7274	@code{ASM_APP_OFF} (if that is enabled). Most ELF assemblers expect\n\
7275	this to be done. The default is false.",
7276	bool, false)
7277
7278	/* Returns true if we should generate exception tables for use with the
7279	ARM EABI. The effects the encoding of function exception specifications. */
7280	DEFHOOKPOD
7281	(arm_eabi_unwinder,
7282	"This flag should be set to @code{true} on targets that use an ARM EABI\n\
7283	based unwinding library, and @code{false} on other targets. This effects\n\
7284	the format of unwinding tables, and how the unwinder in entered after\n\
7285	running a cleanup. The default is @code{false}.",
7286	bool, false)
7287
7288	DEFHOOKPOD
7289	(want_debug_pub_sections,
7290	"True if the @code{.debug_pubtypes} and @code{.debug_pubnames} sections\n\
7291	should be emitted. These sections are not used on most platforms, and\n\
7292	in particular GDB does not use them.",
7293	bool, false)
7294
7295	DEFHOOKPOD
7296	(delay_sched2,
7297	"True if sched2 is not to be run at its normal place.\n\
7298	This usually means it will be run as part of machine-specific reorg.",
7299	bool, false)
7300
7301	DEFHOOKPOD
7302	(delay_vartrack,
7303	"True if vartrack is not to be run at its normal place.\n\
7304	This usually means it will be run as part of machine-specific reorg.",
7305	bool, false)
7306
7307	DEFHOOKPOD
7308	(no_register_allocation,
7309	"True if register allocation and the passes\n\
7310	following it should not be run. Usually true only for virtual assembler\n\
7311	targets.",
7312	bool, false)
7313
7314	/* Leave the boolean fields at the end. */
7315
7316	/* Functions related to mode switching. */
7317	#undef HOOK_PREFIX
7318	#define HOOK_PREFIX "TARGET_MODE_"
7319	HOOK_VECTOR (TARGET_TOGGLE_, mode_switching)
7320
7321	DEFHOOK
7322	(emit,
7323	"Generate one or more insns to set @var{entity} to @var{mode}.\n\
7324	@var{hard_reg_live} is the set of hard registers live at the point where\n\
7325	the insn(s) are to be inserted. @var{prev_moxde} indicates the mode\n\
7326	to switch from, or is the number of modes if the previous mode is not\n\
7327	known. Sets of a lower numbered entity will be emitted before\n\
7328	sets of a higher numbered entity to a mode of the same or lower priority.",
7329	void, (int entity, int mode, int prev_mode, HARD_REG_SET regs_live), NULL)
7330
7331	DEFHOOK
7332	(needed,
7333	"@var{entity} is an integer specifying a mode-switched entity.\n\
7334	If @code{OPTIMIZE_MODE_SWITCHING} is defined, you must define this hook\n\
7335	to return the mode that @var{entity} must be switched into prior to the\n\
7336	execution of @var{insn}, or the number of modes if @var{insn} has no\n\
7337	such requirement. @var{regs_live} contains the set of hard registers\n\
7338	that are live before @var{insn}.",
7339	int, (int entity, rtx_insn *insn, HARD_REG_SET regs_live), NULL)
7340
7341	DEFHOOK
7342	(after,
7343	"@var{entity} is an integer specifying a mode-switched entity.\n\
7344	If this hook is defined, it is evaluated for every @var{insn} during mode\n\
7345	switching. It returns the mode that @var{entity} is in after @var{insn}\n\
7346	has been executed. @var{mode} is the mode that @var{entity} was in\n\
7347	before @var{insn} was executed, taking account of @var{TARGET_MODE_NEEDED}.\n\
7348	@var{regs_live} is the set of hard registers that are live after @var{insn}\n\
7349	has been executed.\n\
7350	\n\
7351	@var{mode} is equal to the number of modes defined for @var{entity}\n\
7352	if the mode before @var{insn} is unknown. The hook should likewise return\n\
7353	the number of modes if it does not know what mode @var{entity} has after\n\
7354	@var{insn}.\n\
7355	\n\
7356	Not defining the hook is equivalent to returning @var{mode}.",
7357	int, (int entity, int mode, rtx_insn *insn, HARD_REG_SET regs_live), NULL)
7358
7359	DEFHOOK
7360	(confluence,
7361	"By default, the mode-switching pass assumes that a given entity's modes\n\
7362	are mutually exclusive. This means that the pass can only tell\n\
7363	@code{TARGET_MODE_EMIT} about an entity's previous mode if all\n\
7364	incoming paths of execution leave the entity in the same state.\n\
7365	\n\
7366	However, some entities might have overlapping, non-exclusive modes,\n\
7367	so that it is sometimes possible to represent ``mode @var{mode1} or mode\n\
7368	@var{mode2}'' with something more specific than ``mode not known''.\n\
7369	If this is true for at least one entity, you should define this hook\n\
7370	and make it return a mode that includes @var{mode1} and @var{mode2}\n\
7371	as possibilities. (The mode can include other possibilities too.)\n\
7372	The hook should return the number of modes if no suitable mode exists\n\
7373	for the given arguments.",
7374	int, (int entity, int mode1, int mode2), NULL)
7375
7376	DEFHOOK
7377	(backprop,
7378	"If defined, the mode-switching pass uses this hook to back-propagate mode\n\
7379	requirements through blocks that have no mode requirements of their own.\n\
7380	Specifically, @var{mode1} is the mode that @var{entity} has on exit\n\
7381	from a block B1 (say) and @var{mode2} is the mode that the next block\n\
7382	requires @var{entity} to have. B1 does not have any mode requirements\n\
7383	of its own.\n\
7384	\n\
7385	The hook should return the mode that it prefers or requires @var{entity}\n\
7386	to have in B1, or the number of modes if there is no such requirement.\n\
7387	If the hook returns a required mode for more than one of B1's outgoing\n\
7388	edges, those modes are combined as for @code{TARGET_MODE_CONFLUENCE}.\n\
7389	\n\
7390	For example, suppose there is a ``one-shot'' entity that,\n\
7391	for a given execution of a function, either stays off or makes exactly\n\
7392	one transition from off to on. It is safe to make the transition at any\n\
7393	time, but it is better not to do so unnecessarily. This hook allows the\n\
7394	function to manage such an entity without having to track its state at\n\
7395	runtime. Specifically. the entity would have two modes, 0 for off and\n\
7396	1 for on, with 2 representing ``don't know''. The system is forbidden from\n\
7397	transitioning from 2 to 1, since 2 represents the possibility that the\n\
7398	entity is already on (and the aim is to avoid having to emit code to\n\
7399	check for that case). This hook would therefore return 1 when @var{mode1}\n\
7400	is 2 and @var{mode2} is 1, which would force the entity to be on in the\n\
7401	source block. Applying this inductively would remove all transitions\n\
7402	in which the previous state is unknown.",
7403	int, (int entity, int mode1, int mode2), NULL)
7404
7405	DEFHOOK
7406	(entry,
7407	"If this hook is defined, it is evaluated for every @var{entity} that\n\
7408	needs mode switching. It should return the mode that @var{entity} is\n\
7409	guaranteed to be in on entry to the function, or the number of modes\n\
7410	if there is no such guarantee.\n\
7411	If @code{TARGET_MODE_ENTRY} is defined then @code{TARGET_MODE_EXIT}\n\
7412	must be defined.",
7413	int, (int entity), NULL)
7414
7415	DEFHOOK
7416	(exit,
7417	"If this hook is defined, it is evaluated for every @var{entity} that\n\
7418	needs mode switching. It should return the mode that @var{entity} must\n\
7419	be in on return from the function, or the number of modes if there is no\n\
7420	such requirement.\n\
7421	If @code{TARGET_MODE_EXIT} is defined then @code{TARGET_MODE_ENTRY}\n\
7422	must be defined.",
7423	int, (int entity), NULL)
7424
7425	DEFHOOK
7426	(eh_handler,
7427	"If this hook is defined, it should return the mode that @var{entity} is\n\
7428	guaranteed to be in on entry to an exception handler, or the number of modes\n\
7429	if there is no such guarantee.",
7430	int, (int entity), NULL)
7431
7432	DEFHOOK
7433	(priority,
7434	"This hook specifies the order in which modes for @var{entity}\n\
7435	are processed. 0 is the highest priority,\n\
7436	@code{NUM_MODES_FOR_MODE_SWITCHING[@var{entity}] - 1} the lowest.\n\
7437	The hook returns an integer designating a mode\n\
7438	for @var{entity}. For any fixed @var{entity}, @code{mode_priority}\n\
7439	(@var{entity}, @var{n}) shall be a bijection in 0 @dots{}\n\
7440	@code{num_modes_for_mode_switching[@var{entity}] - 1}.",
7441	int, (int entity, int n), NULL)
7442
7443	HOOK_VECTOR_END (mode_switching)
7444
7445	#undef HOOK_PREFIX
7446	#define HOOK_PREFIX "TARGET_MEMTAG_"
7447	HOOK_VECTOR (TARGET_MEMTAG_, memtag)
7448
7449	DEFHOOK
7450	(can_tag_addresses,
7451	"True if the backend architecture naturally supports ignoring some region\n\
7452	of pointers. This feature means that @option{-fsanitize=hwaddress} can\n\
7453	work.\n\
7454	\n\
7455	At preset, this feature does not support address spaces. It also requires\n\
7456	@code{Pmode} to be the same as @code{ptr_mode}.",
7457	bool, (), default_memtag_can_tag_addresses)
7458
7459	DEFHOOK
7460	(tag_size,
7461	"Return the size of a tag (in bits) for this platform.\n\
7462	\n\
7463	The default returns 8.",
7464	uint8_t, (), default_memtag_tag_size)
7465
7466	DEFHOOK
7467	(granule_size,
7468	"Return the size in real memory that each byte in shadow memory refers to.\n\
7469	I.e. if a variable is @var{X} bytes long in memory, then this hook should\n\
7470	return the value @var{Y} such that the tag in shadow memory spans\n\
7471	@var{X}/@var{Y} bytes.\n\
7472	\n\
7473	Most variables will need to be aligned to this amount since two variables\n\
7474	that are neighbors in memory and share a tag granule would need to share\n\
7475	the same tag.\n\
7476	\n\
7477	The default returns 16.",
7478	uint8_t, (), default_memtag_granule_size)
7479
7480	DEFHOOK
7481	(insert_random_tag,
7482	"Return an RTX representing the value of @var{untagged} but with a\n\
7483	(possibly) random tag in it.\n\
7484	Put that value into @var{target} if it is convenient to do so.\n\
7485	This function is used to generate a tagged base for the current stack frame.",
7486	rtx, (rtx untagged, rtx target), default_memtag_insert_random_tag)
7487
7488	DEFHOOK
7489	(add_tag,
7490	"Return an RTX that represents the result of adding @var{addr_offset} to\n\
7491	the address in pointer @var{base} and @var{tag_offset} to the tag in pointer\n\
7492	@var{base}.\n\
7493	The resulting RTX must either be a valid memory address or be able to get\n\
7494	put into an operand with @code{force_operand}.\n\
7495	\n\
7496	Unlike other memtag hooks, this must return an expression and not emit any\n\
7497	RTL.",
7498	rtx, (rtx base, poly_int64 addr_offset, uint8_t tag_offset),
7499	default_memtag_add_tag)
7500
7501	DEFHOOK
7502	(set_tag,
7503	"Return an RTX representing @var{untagged_base} but with the tag @var{tag}.\n\
7504	Try and store this in @var{target} if convenient.\n\
7505	@var{untagged_base} is required to have a zero tag when this hook is called.\n\
7506	The default of this hook is to set the top byte of @var{untagged_base} to\n\
7507	@var{tag}.",
7508	rtx, (rtx untagged_base, rtx tag, rtx target), default_memtag_set_tag)
7509
7510	DEFHOOK
7511	(extract_tag,
7512	"Return an RTX representing the tag stored in @var{tagged_pointer}.\n\
7513	Store the result in @var{target} if it is convenient.\n\
7514	The default represents the top byte of the original pointer.",
7515	rtx, (rtx tagged_pointer, rtx target), default_memtag_extract_tag)
7516
7517	DEFHOOK
7518	(untagged_pointer,
7519	"Return an RTX representing @var{tagged_pointer} with its tag set to zero.\n\
7520	Store the result in @var{target} if convenient.\n\
7521	The default clears the top byte of the original pointer.",
7522	rtx, (rtx tagged_pointer, rtx target), default_memtag_untagged_pointer)
7523
7524	HOOK_VECTOR_END (memtag)
7525	#undef HOOK_PREFIX
7526	#define HOOK_PREFIX "TARGET_"
7527
7528	#define DEF_TARGET_INSN(NAME, PROTO) \
7529	DEFHOOK_UNDOC (have_##NAME, "", bool, (void), false)
7530	#include "target-insns.def"
7531	#undef DEF_TARGET_INSN
7532
7533	#define DEF_TARGET_INSN(NAME, PROTO) \
7534	DEFHOOK_UNDOC (gen_##NAME, "", rtx_insn *, PROTO, NULL)
7535	#include "target-insns.def"
7536	#undef DEF_TARGET_INSN
7537
7538	#define DEF_TARGET_INSN(NAME, PROTO) \
7539	DEFHOOKPOD (code_for_##NAME, "*", enum insn_code, CODE_FOR_nothing)
7540	#include "target-insns.def"
7541	#undef DEF_TARGET_INSN
7542
7543	DEFHOOK
7544	(run_target_selftests,
7545	"If selftests are enabled, run any selftests for this target.",
7546	void, (void),
7547	NULL)
7548
7549	/* This value represents whether the shadow call stack is implemented on
7550	the target platform. */
7551	DEFHOOKPOD
7552	(have_shadow_call_stack,
7553	"This value is true if the target platform supports\n\
7554	@option{-fsanitize=shadow-call-stack}. The default value is false.",
7555	bool, false)
7556
7557	/* This value represents whether libatomic is available on
7558	the target platform. */
7559	DEFHOOKPOD
7560	(have_libatomic,
7561	"This value is true if the target platform supports\n\
7562	libatomic. The default value is false.",
7563	bool, false)
7564
7565	/* This value represents whether libatomic is available on
7566	the target platform. */
7567	DEFHOOKPOD
7568	(documentation_name,
7569	"If non-NULL, this value is a string used for locating target-specific\
7570	documentation for this target.\n\
7571	The default value is NULL.",
7572	const char *, NULL)
7573
7574	/* Close the 'struct gcc_target' definition. */
7575	HOOK_VECTOR_END (C90_EMPTY_HACK)
7576
7577