1/* elfos.h -- operating system specific defines to be used when
2 targeting GCC for some generic ELF system
3 Copyright (C) 1991-2025 Free Software Foundation, Inc.
4 Based on svr4.h contributed by Ron Guilmette (rfg@netcom.com).
5
6This file is part of GCC.
7
8GCC is free software; you can redistribute it and/or modify
9it under the terms of the GNU General Public License as published by
10the Free Software Foundation; either version 3, or (at your option)
11any later version.
12
13GCC is distributed in the hope that it will be useful,
14but WITHOUT ANY WARRANTY; without even the implied warranty of
15MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16GNU General Public License for more details.
17
18Under Section 7 of GPL version 3, you are granted additional
19permissions described in the GCC Runtime Library Exception, version
203.1, as published by the Free Software Foundation.
21
22You should have received a copy of the GNU General Public License and
23a copy of the GCC Runtime Library Exception along with this program;
24see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
25<http://www.gnu.org/licenses/>. */
26
27#define TARGET_OBJFMT_CPP_BUILTINS() \
28 do \
29 { \
30 builtin_define ("__ELF__"); \
31 } \
32 while (0)
33
34/* Define a symbol indicating that we are using elfos.h.
35 Some CPU specific configuration files use this. */
36#define USING_ELFOS_H
37
38/* The prefix to add to user-visible assembler symbols.
39
40 For ELF systems the convention is *not* to prepend a leading
41 underscore onto user-level symbol names. */
42
43#undef USER_LABEL_PREFIX
44#define USER_LABEL_PREFIX ""
45
46/* The biggest alignment supported by ELF in bits. 32-bit ELF
47 supports section alignment up to (0x80000000 * 8), while
48 64-bit ELF supports (0x8000000000000000 * 8). If this macro
49 is not defined, the default is the largest alignment supported
50 by 32-bit ELF and representable on a 32-bit host. Use this
51 macro to limit the alignment which can be specified using
52 the `__attribute__ ((aligned (N)))' construct. */
53#ifndef MAX_OFILE_ALIGNMENT
54#define MAX_OFILE_ALIGNMENT (((unsigned int) 1 << 28) * 8)
55#endif
56
57/* Use periods rather than dollar signs in special g++ assembler names. */
58
59#define NO_DOLLAR_IN_LABEL
60
61/* Writing `int' for a bit-field forces int alignment for the structure. */
62
63#ifndef PCC_BITFIELD_TYPE_MATTERS
64#define PCC_BITFIELD_TYPE_MATTERS 1
65#endif
66
67/* All ELF targets can support DWARF-2. */
68
69#define DWARF2_DEBUGGING_INFO 1
70
71/* All ELF targets can support CTF. */
72
73#define CTF_DEBUGGING_INFO 1
74
75/* All ELF targets can support BTF. */
76
77#define BTF_DEBUGGING_INFO 1
78
79/* The GNU tools operate better with dwarf2, and it is required by some
80 psABI's. Since we don't have any native tools to be compatible with,
81 default to dwarf2. */
82
83#ifndef PREFERRED_DEBUGGING_TYPE
84#define PREFERRED_DEBUGGING_TYPE DWARF2_DEBUG
85#endif
86
87/* All SVR4 targets use the ELF object file format. */
88#define OBJECT_FORMAT_ELF
89
90
91/* Output #ident as a .ident. */
92
93#undef TARGET_ASM_OUTPUT_IDENT
94#define TARGET_ASM_OUTPUT_IDENT default_asm_output_ident_directive
95
96#undef SET_ASM_OP
97#define SET_ASM_OP "\t.set\t"
98
99/* Most svr4 assemblers want a .file directive at the beginning of
100 their input file. */
101#define TARGET_ASM_FILE_START_FILE_DIRECTIVE true
102
103/* This is how to allocate empty space in some section. The .zero
104 pseudo-op is used for this on most svr4 assemblers. */
105
106#define SKIP_ASM_OP "\t.zero\t"
107
108#undef ASM_OUTPUT_SKIP
109#define ASM_OUTPUT_SKIP(FILE, SIZE) \
110 fprintf ((FILE), "%s" HOST_WIDE_INT_PRINT_UNSIGNED "\n",\
111 SKIP_ASM_OP, (SIZE))
112
113/* This is how to store into the string LABEL
114 the symbol_ref name of an internal numbered label where
115 PREFIX is the class of label and NUM is the number within the class.
116 This is suitable for output with `assemble_name'.
117
118 For most svr4 systems, the convention is that any symbol which begins
119 with a period is not put into the linker symbol table by the assembler. */
120
121#undef ASM_GENERATE_INTERNAL_LABEL
122#define ASM_GENERATE_INTERNAL_LABEL(LABEL, PREFIX, NUM) \
123 do \
124 { \
125 char *__p; \
126 (LABEL)[0] = '*'; \
127 (LABEL)[1] = '.'; \
128 __p = stpcpy (&(LABEL)[2], PREFIX); \
129 sprint_ul (__p, (unsigned long) (NUM)); \
130 } \
131 while (0)
132
133/* Output the label which precedes a jumptable. Note that for all svr4
134 systems where we actually generate jumptables (which is to say every
135 svr4 target except i386, where we use casesi instead) we put the jump-
136 tables into the .rodata section and since other stuff could have been
137 put into the .rodata section prior to any given jumptable, we have to
138 make sure that the location counter for the .rodata section gets pro-
139 perly re-aligned prior to the actual beginning of the jump table. */
140
141#undef ALIGN_ASM_OP
142#define ALIGN_ASM_OP "\t.align\t"
143
144#ifndef ASM_OUTPUT_BEFORE_CASE_LABEL
145#define ASM_OUTPUT_BEFORE_CASE_LABEL(FILE, PREFIX, NUM, TABLE) \
146 ASM_OUTPUT_ALIGN ((FILE), 2)
147#endif
148
149#undef ASM_OUTPUT_CASE_LABEL
150#define ASM_OUTPUT_CASE_LABEL(FILE, PREFIX, NUM, JUMPTABLE) \
151 do \
152 { \
153 ASM_OUTPUT_BEFORE_CASE_LABEL (FILE, PREFIX, NUM, JUMPTABLE); \
154 (*targetm.asm_out.internal_label) (FILE, PREFIX, NUM); \
155 } \
156 while (0)
157
158/* The standard SVR4 assembler seems to require that certain builtin
159 library routines (e.g. .udiv) be explicitly declared as .globl
160 in each assembly file where they are referenced. */
161
162#define ASM_OUTPUT_EXTERNAL_LIBCALL(FILE, FUN) \
163 (*targetm.asm_out.globalize_label) (FILE, XSTR (FUN, 0))
164
165/* This says how to output assembler code to declare an
166 uninitialized external linkage data object. Under SVR4,
167 the linker seems to want the alignment of data objects
168 to depend on their types. We do exactly that here. */
169
170#define COMMON_ASM_OP "\t.comm\t"
171
172#undef ASM_OUTPUT_ALIGNED_COMMON
173#define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN) \
174 do \
175 { \
176 fprintf ((FILE), "%s", COMMON_ASM_OP); \
177 assemble_name ((FILE), (NAME)); \
178 fprintf ((FILE), "," HOST_WIDE_INT_PRINT_UNSIGNED ",%u\n", \
179 (SIZE), (ALIGN) / BITS_PER_UNIT); \
180 } \
181 while (0)
182
183/* This says how to output assembler code to declare an
184 uninitialized internal linkage data object. Under SVR4,
185 the linker seems to want the alignment of data objects
186 to depend on their types. We do exactly that here. */
187
188#define LOCAL_ASM_OP "\t.local\t"
189
190#undef ASM_OUTPUT_ALIGNED_LOCAL
191#define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGN) \
192 do \
193 { \
194 fprintf ((FILE), "%s", LOCAL_ASM_OP); \
195 assemble_name ((FILE), (NAME)); \
196 fprintf ((FILE), "\n"); \
197 ASM_OUTPUT_ALIGNED_COMMON (FILE, NAME, SIZE, ALIGN); \
198 } \
199 while (0)
200
201/* This is the pseudo-op used to generate a contiguous sequence of byte
202 values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
203 AUTOMATICALLY APPENDED. This is the same for most svr4 assemblers. */
204
205#undef ASCII_DATA_ASM_OP
206#define ASCII_DATA_ASM_OP "\t.ascii\t"
207
208/* Support a read-only data section. */
209#define READONLY_DATA_SECTION_ASM_OP "\t.section\t.rodata"
210
211/* On svr4, we *do* have support for the .init and .fini sections, and we
212 can put stuff in there to be executed before and after `main'. We let
213 crtstuff.c and other files know this by defining the following symbols.
214 The definitions say how to change sections to the .init and .fini
215 sections. This is the same for all known svr4 assemblers. */
216
217#define INIT_SECTION_ASM_OP "\t.section\t.init"
218#define FINI_SECTION_ASM_OP "\t.section\t.fini"
219
220/* Output assembly directive to move to the beginning of current section. */
221#ifdef HAVE_GAS_SUBSECTION_ORDERING
222# define ASM_SECTION_START_OP "\t.subsection\t-1"
223# define ASM_OUTPUT_SECTION_START(FILE) \
224 fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
225#endif
226
227#define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
228
229/* Switch into a generic section. */
230#define TARGET_ASM_NAMED_SECTION default_elf_asm_named_section
231
232#undef TARGET_ASM_SELECT_RTX_SECTION
233#define TARGET_ASM_SELECT_RTX_SECTION default_elf_select_rtx_section
234#undef TARGET_ASM_SELECT_SECTION
235#define TARGET_ASM_SELECT_SECTION default_elf_select_section
236#undef TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
237#define TARGET_HAVE_SWITCHABLE_BSS_SECTIONS true
238
239/* Define the strings used for the special svr4 .type and .size directives.
240 These strings generally do not vary from one system running svr4 to
241 another, but if a given system (e.g. m88k running svr) needs to use
242 different pseudo-op names for these, they may be overridden in the
243 file which includes this one. */
244
245#define TYPE_ASM_OP "\t.type\t"
246#define SIZE_ASM_OP "\t.size\t"
247
248/* This is how we tell the assembler that a symbol is weak. */
249
250#define ASM_WEAKEN_LABEL(FILE, NAME) \
251 do \
252 { \
253 fputs ("\t.weak\t", (FILE)); \
254 assemble_name ((FILE), (NAME)); \
255 fputc ('\n', (FILE)); \
256 } \
257 while (0)
258
259#define ASM_OUTPUT_SYMVER_DIRECTIVE(FILE, NAME, NAME2) \
260 do \
261 { \
262 fputs ("\t.symver\t", (FILE)); \
263 assemble_name ((FILE), (NAME)); \
264 fputs (", ", (FILE)); \
265 assemble_name ((FILE), (NAME2)); \
266 fputc ('\n', (FILE)); \
267 } \
268 while (0)
269
270/* The following macro defines the format used to output the second
271 operand of the .type assembler directive. Different svr4 assemblers
272 expect various different forms for this operand. The one given here
273 is just a default. You may need to override it in your machine-
274 specific tm.h file (depending upon the particulars of your assembler). */
275
276#define TYPE_OPERAND_FMT "@%s"
277
278/* Write the extra assembler code needed to declare a function's result.
279 Most svr4 assemblers don't require any special declaration of the
280 result value, but there are exceptions. */
281
282#ifndef ASM_DECLARE_RESULT
283#define ASM_DECLARE_RESULT(FILE, RESULT)
284#endif
285
286/* These macros generate the special .type and .size directives which
287 are used to set the corresponding fields of the linker symbol table
288 entries in an ELF object file under SVR4. These macros also output
289 the starting labels for the relevant functions/objects. */
290
291/* Write the extra assembler code needed to declare a function properly.
292 Some svr4 assemblers need to also have something extra said about the
293 function's return value. We allow for that here. */
294
295#ifndef ASM_DECLARE_FUNCTION_NAME
296#define ASM_DECLARE_FUNCTION_NAME(FILE, NAME, DECL) \
297 do \
298 { \
299 ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "function"); \
300 ASM_DECLARE_RESULT (FILE, DECL_RESULT (DECL)); \
301 ASM_OUTPUT_FUNCTION_LABEL (FILE, NAME, DECL); \
302 } \
303 while (0)
304#endif
305
306/* Write the extra assembler code needed to declare the name of a
307 cold function partition properly. Some svr4 assemblers need to also
308 have something extra said about the function's return value. We
309 allow for that here. */
310
311#ifndef ASM_DECLARE_COLD_FUNCTION_NAME
312#define ASM_DECLARE_COLD_FUNCTION_NAME(FILE, NAME, DECL) \
313 do \
314 { \
315 ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "function"); \
316 ASM_DECLARE_RESULT (FILE, DECL_RESULT (DECL)); \
317 ASM_OUTPUT_FUNCTION_LABEL (FILE, NAME, DECL); \
318 } \
319 while (0)
320#endif
321
322/* Write the extra assembler code needed to declare an object properly. */
323
324#ifdef HAVE_GAS_GNU_UNIQUE_OBJECT
325#define USE_GNU_UNIQUE_OBJECT flag_gnu_unique
326#else
327#define USE_GNU_UNIQUE_OBJECT 0
328#endif
329
330#define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL) \
331 do \
332 { \
333 HOST_WIDE_INT size; \
334 \
335 /* For template static data member instantiations or \
336 inline fn local statics and their guard variables, use \
337 gnu_unique_object so that they will be combined even under \
338 RTLD_LOCAL. Don't use gnu_unique_object for typeinfo, \
339 vtables and other read-only artificial decls. */ \
340 if (USE_GNU_UNIQUE_OBJECT && DECL_ONE_ONLY (DECL) \
341 && (!DECL_ARTIFICIAL (DECL) || !TREE_READONLY (DECL))) \
342 ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "gnu_unique_object"); \
343 else \
344 ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object"); \
345 \
346 size_directive_output = 0; \
347 if (!flag_inhibit_size_directive \
348 && (DECL) && DECL_SIZE (DECL)) \
349 { \
350 size_directive_output = 1; \
351 size = tree_to_uhwi (DECL_SIZE_UNIT (DECL)); \
352 ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, size); \
353 } \
354 \
355 ASM_OUTPUT_LABEL (FILE, NAME); \
356 } \
357 while (0)
358
359/* Output the size directive for a decl in rest_of_decl_compilation
360 in the case where we did not do so before the initializer.
361 Once we find the error_mark_node, we know that the value of
362 size_directive_output was set
363 by ASM_DECLARE_OBJECT_NAME when it was run for the same decl. */
364
365#undef ASM_FINISH_DECLARE_OBJECT
366#define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)\
367 do \
368 { \
369 const char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0); \
370 HOST_WIDE_INT size; \
371 \
372 if (!flag_inhibit_size_directive \
373 && DECL_SIZE (DECL) \
374 && ! AT_END && TOP_LEVEL \
375 && DECL_INITIAL (DECL) == error_mark_node \
376 && !size_directive_output) \
377 { \
378 size_directive_output = 1; \
379 size = tree_to_uhwi (DECL_SIZE_UNIT (DECL)); \
380 ASM_OUTPUT_SIZE_DIRECTIVE (FILE, name, size); \
381 } \
382 } \
383 while (0)
384
385/* This is how to declare the size of a function. */
386#ifndef ASM_DECLARE_FUNCTION_SIZE
387#define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL) \
388 do \
389 { \
390 if (!flag_inhibit_size_directive) \
391 ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME); \
392 } \
393 while (0)
394#endif
395
396/* This is how to declare the size of a cold function partition. */
397#ifndef ASM_DECLARE_COLD_FUNCTION_SIZE
398#define ASM_DECLARE_COLD_FUNCTION_SIZE(FILE, FNAME, DECL) \
399 do \
400 { \
401 if (!flag_inhibit_size_directive) \
402 ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME); \
403 } \
404 while (0)
405#endif
406
407/* A table of bytes codes used by the ASM_OUTPUT_ASCII and
408 ASM_OUTPUT_LIMITED_STRING macros. Each byte in the table
409 corresponds to a particular byte value [0..255]. For any
410 given byte value, if the value in the corresponding table
411 position is zero, the given character can be output directly.
412 If the table value is 1, the byte must be output as a \ooo
413 octal escape. If the tables value is anything else, then the
414 byte value should be output as a \ followed by the value
415 in the table. Note that we can use standard UN*X escape
416 sequences for many control characters, but we don't use
417 \a to represent BEL because some svr4 assemblers (e.g. on
418 the i386) don't know about that. Also, we don't use \v
419 since some versions of gas, such as 2.2 did not accept it. */
420
421#define ELF_ASCII_ESCAPES \
422"\1\1\1\1\1\1\1\1btn\1fr\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\
423\0\0\"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
424\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\\\0\0\0\
425\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1\
426\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\
427\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\
428\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\
429\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1"
430
431/* Some svr4 assemblers have a limit on the number of characters which
432 can appear in the operand of a .string directive. If your assembler
433 has such a limitation, you should define STRING_LIMIT to reflect that
434 limit. Note that at least some svr4 assemblers have a limit on the
435 actual number of bytes in the double-quoted string, and that they
436 count each character in an escape sequence as one byte. Thus, an
437 escape sequence like \377 would count as four bytes.
438
439 If your target assembler doesn't support the .string directive, you
440 should define this to zero.
441*/
442
443#define ELF_STRING_LIMIT ((unsigned) 256)
444
445#define STRING_ASM_OP "\t.string\t"
446
447#ifdef HAVE_GAS_BASE64
448#define BASE64_ASM_OP "\t.base64\t"
449#endif
450
451/* The routine used to output NUL terminated strings. We use a special
452 version of this for most svr4 targets because doing so makes the
453 generated assembly code more compact (and thus faster to assemble)
454 as well as more readable, especially for targets like the i386
455 (where the only alternative is to output character sequences as
456 comma separated lists of numbers). */
457
458#define ASM_OUTPUT_LIMITED_STRING(FILE, STR) \
459 default_elf_asm_output_limited_string ((FILE), (STR))
460
461/* The routine used to output sequences of byte values. We use a special
462 version of this for most svr4 targets because doing so makes the
463 generated assembly code more compact (and thus faster to assemble)
464 as well as more readable. Note that if we find subparts of the
465 character sequence which end with NUL (and which are shorter than
466 STRING_LIMIT) we output those using ASM_OUTPUT_LIMITED_STRING. */
467
468#undef ASM_OUTPUT_ASCII
469#define ASM_OUTPUT_ASCII(FILE, STR, LENGTH) \
470 default_elf_asm_output_ascii ((FILE), (STR), (LENGTH))
471
472/* Allow the use of the -frecord-gcc-switches switch via the
473 elf_record_gcc_switches function defined in varasm.cc. */
474#undef TARGET_ASM_RECORD_GCC_SWITCHES
475#define TARGET_ASM_RECORD_GCC_SWITCHES elf_record_gcc_switches
476
477/* A C statement (sans semicolon) to output to the stdio stream STREAM
478 any text necessary for declaring the name of an external symbol
479 named NAME which is referenced in this compilation but not defined.
480 It is needed to properly support non-default visibility. */
481
482#ifndef ASM_OUTPUT_EXTERNAL
483#define ASM_OUTPUT_EXTERNAL(FILE, DECL, NAME) \
484 default_elf_asm_output_external (FILE, DECL, NAME)
485#endif
486
487#undef TARGET_LIBC_HAS_FUNCTION
488#define TARGET_LIBC_HAS_FUNCTION no_c99_libc_has_function
489

source code of gcc/config/elfos.h