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1 | \input texinfo @c -*-Texinfo-*- | |
2 | @c Copyright (C) 1991-2018 Free Software Foundation, Inc. | |
3 | @c UPDATE!! On future updates-- | |
4 | @c (1) check for new machine-dep cmdline options in | |
5 | @c md_parse_option definitions in config/tc-*.c | |
6 | @c (2) for platform-specific directives, examine md_pseudo_op | |
7 | @c in config/tc-*.c | |
8 | @c (3) for object-format specific directives, examine obj_pseudo_op | |
9 | @c in config/obj-*.c | |
10 | @c (4) portable directives in potable[] in read.c | |
11 | @c %**start of header | |
12 | @setfilename as.info | |
13 | @c ---config--- | |
14 | @macro gcctabopt{body} | |
15 | @code{\body\} | |
16 | @end macro | |
17 | @c defaults, config file may override: | |
18 | @set have-stabs | |
19 | @c --- | |
20 | @c man begin NAME | |
21 | @c --- | |
22 | @include asconfig.texi | |
23 | @include bfdver.texi | |
24 | @c --- | |
25 | @c man end | |
26 | @c --- | |
27 | @c common OR combinations of conditions | |
28 | @ifset COFF | |
29 | @set COFF-ELF | |
30 | @end ifset | |
31 | @ifset ELF | |
32 | @set COFF-ELF | |
33 | @end ifset | |
34 | @ifset AOUT | |
35 | @set aout | |
36 | @end ifset | |
37 | @ifset ARM/Thumb | |
38 | @set ARM | |
39 | @end ifset | |
40 | @ifset Blackfin | |
41 | @set Blackfin | |
42 | @end ifset | |
43 | @ifset H8/300 | |
44 | @set H8 | |
45 | @end ifset | |
46 | @ifset SH | |
47 | @set H8 | |
48 | @end ifset | |
49 | @ifset HPPA | |
50 | @set abnormal-separator | |
51 | @end ifset | |
52 | @c ------------ | |
53 | @ifset GENERIC | |
54 | @settitle Using @value{AS} | |
55 | @end ifset | |
56 | @ifclear GENERIC | |
57 | @settitle Using @value{AS} (@value{TARGET}) | |
58 | @end ifclear | |
59 | @setchapternewpage odd | |
60 | @c %**end of header | |
61 | ||
62 | @c @smallbook | |
63 | @c @set SMALL | |
64 | @c WARE! Some of the machine-dependent sections contain tables of machine | |
65 | @c instructions. Except in multi-column format, these tables look silly. | |
66 | @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so | |
67 | @c the multi-col format is faked within @example sections. | |
68 | @c | |
69 | @c Again unfortunately, the natural size that fits on a page, for these tables, | |
70 | @c is different depending on whether or not smallbook is turned on. | |
71 | @c This matters, because of order: text flow switches columns at each page | |
72 | @c break. | |
73 | @c | |
74 | @c The format faked in this source works reasonably well for smallbook, | |
75 | @c not well for the default large-page format. This manual expects that if you | |
76 | @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the | |
77 | @c tables in question. You can turn on one without the other at your | |
78 | @c discretion, of course. | |
79 | @ifinfo | |
80 | @set SMALL | |
81 | @c the insn tables look just as silly in info files regardless of smallbook, | |
82 | @c might as well show 'em anyways. | |
83 | @end ifinfo | |
84 | ||
85 | @ifnottex | |
86 | @dircategory Software development | |
87 | @direntry | |
88 | * As: (as). The GNU assembler. | |
89 | * Gas: (as). The GNU assembler. | |
90 | @end direntry | |
91 | @end ifnottex | |
92 | ||
93 | @finalout | |
94 | @syncodeindex ky cp | |
95 | ||
96 | @copying | |
97 | This file documents the GNU Assembler "@value{AS}". | |
98 | ||
99 | @c man begin COPYRIGHT | |
100 | Copyright @copyright{} 1991-2018 Free Software Foundation, Inc. | |
101 | ||
102 | Permission is granted to copy, distribute and/or modify this document | |
103 | under the terms of the GNU Free Documentation License, Version 1.3 | |
104 | or any later version published by the Free Software Foundation; | |
105 | with no Invariant Sections, with no Front-Cover Texts, and with no | |
106 | Back-Cover Texts. A copy of the license is included in the | |
107 | section entitled ``GNU Free Documentation License''. | |
108 | ||
109 | @c man end | |
110 | @end copying | |
111 | ||
112 | @titlepage | |
113 | @title Using @value{AS} | |
114 | @subtitle The @sc{gnu} Assembler | |
115 | @ifclear GENERIC | |
116 | @subtitle for the @value{TARGET} family | |
117 | @end ifclear | |
118 | @ifset VERSION_PACKAGE | |
119 | @sp 1 | |
120 | @subtitle @value{VERSION_PACKAGE} | |
121 | @end ifset | |
122 | @sp 1 | |
123 | @subtitle Version @value{VERSION} | |
124 | @sp 1 | |
125 | @sp 13 | |
126 | The Free Software Foundation Inc.@: thanks The Nice Computer | |
127 | Company of Australia for loaning Dean Elsner to write the | |
128 | first (Vax) version of @command{as} for Project @sc{gnu}. | |
129 | The proprietors, management and staff of TNCCA thank FSF for | |
130 | distracting the boss while they got some work | |
131 | done. | |
132 | @sp 3 | |
133 | @author Dean Elsner, Jay Fenlason & friends | |
134 | @page | |
135 | @tex | |
136 | {\parskip=0pt | |
137 | \hfill {\it Using {\tt @value{AS}}}\par | |
138 | \hfill Edited by Cygnus Support\par | |
139 | } | |
140 | %"boxit" macro for figures: | |
141 | %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3) | |
142 | \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt | |
143 | \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil | |
144 | #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline | |
145 | \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box | |
146 | @end tex | |
147 | ||
148 | @vskip 0pt plus 1filll | |
149 | Copyright @copyright{} 1991-2018 Free Software Foundation, Inc. | |
150 | ||
151 | Permission is granted to copy, distribute and/or modify this document | |
152 | under the terms of the GNU Free Documentation License, Version 1.3 | |
153 | or any later version published by the Free Software Foundation; | |
154 | with no Invariant Sections, with no Front-Cover Texts, and with no | |
155 | Back-Cover Texts. A copy of the license is included in the | |
156 | section entitled ``GNU Free Documentation License''. | |
157 | ||
158 | @end titlepage | |
159 | @contents | |
160 | ||
161 | @ifnottex | |
162 | @node Top | |
163 | @top Using @value{AS} | |
164 | ||
165 | This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} | |
166 | @ifset VERSION_PACKAGE | |
167 | @value{VERSION_PACKAGE} | |
168 | @end ifset | |
169 | version @value{VERSION}. | |
170 | @ifclear GENERIC | |
171 | This version of the file describes @command{@value{AS}} configured to generate | |
172 | code for @value{TARGET} architectures. | |
173 | @end ifclear | |
174 | ||
175 | This document is distributed under the terms of the GNU Free | |
176 | Documentation License. A copy of the license is included in the | |
177 | section entitled ``GNU Free Documentation License''. | |
178 | ||
179 | @menu | |
180 | * Overview:: Overview | |
181 | * Invoking:: Command-Line Options | |
182 | * Syntax:: Syntax | |
183 | * Sections:: Sections and Relocation | |
184 | * Symbols:: Symbols | |
185 | * Expressions:: Expressions | |
186 | * Pseudo Ops:: Assembler Directives | |
187 | @ifset ELF | |
188 | * Object Attributes:: Object Attributes | |
189 | @end ifset | |
190 | * Machine Dependencies:: Machine Dependent Features | |
191 | * Reporting Bugs:: Reporting Bugs | |
192 | * Acknowledgements:: Who Did What | |
193 | * GNU Free Documentation License:: GNU Free Documentation License | |
194 | * AS Index:: AS Index | |
195 | @end menu | |
196 | @end ifnottex | |
197 | ||
198 | @node Overview | |
199 | @chapter Overview | |
200 | @iftex | |
201 | This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}. | |
202 | @ifclear GENERIC | |
203 | This version of the manual describes @command{@value{AS}} configured to generate | |
204 | code for @value{TARGET} architectures. | |
205 | @end ifclear | |
206 | @end iftex | |
207 | ||
208 | @cindex invocation summary | |
209 | @cindex option summary | |
210 | @cindex summary of options | |
211 | Here is a brief summary of how to invoke @command{@value{AS}}. For details, | |
212 | see @ref{Invoking,,Command-Line Options}. | |
213 | ||
214 | @c man title AS the portable GNU assembler. | |
215 | ||
216 | @ignore | |
217 | @c man begin SEEALSO | |
218 | gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}. | |
219 | @c man end | |
220 | @end ignore | |
221 | ||
222 | @c We don't use deffn and friends for the following because they seem | |
223 | @c to be limited to one line for the header. | |
224 | @smallexample | |
225 | @c man begin SYNOPSIS | |
226 | @value{AS} [@b{-a}[@b{cdghlns}][=@var{file}]] [@b{--alternate}] [@b{-D}] | |
227 | [@b{--compress-debug-sections}] [@b{--nocompress-debug-sections}] | |
228 | [@b{--debug-prefix-map} @var{old}=@var{new}] | |
229 | [@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}] | |
230 | [@b{--gstabs+}] [@b{--gdwarf-2}] [@b{--gdwarf-sections}] | |
231 | [@b{--help}] [@b{-I} @var{dir}] [@b{-J}] | |
232 | [@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}] | |
233 | [@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}] | |
234 | [@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}] | |
235 | [@b{--no-pad-sections}] | |
236 | [@b{-o} @var{objfile}] [@b{-R}] | |
237 | [@b{--hash-size}=@var{NUM}] [@b{--reduce-memory-overheads}] | |
238 | [@b{--statistics}] | |
239 | [@b{-v}] [@b{-version}] [@b{--version}] | |
240 | [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}] [@b{-w}] [@b{-x}] | |
241 | [@b{-Z}] [@b{@@@var{FILE}}] | |
242 | [@b{--sectname-subst}] [@b{--size-check=[error|warning]}] | |
243 | [@b{--elf-stt-common=[no|yes]}] | |
244 | [@b{--generate-missing-build-notes=[no|yes]}] | |
245 | [@b{--target-help}] [@var{target-options}] | |
246 | [@b{--}|@var{files} @dots{}] | |
247 | @c | |
248 | @c man end | |
249 | @c Target dependent options are listed below. Keep the list sorted. | |
250 | @c Add an empty line for separation. | |
251 | @c man begin TARGET | |
252 | @ifset AARCH64 | |
253 | ||
254 | @emph{Target AArch64 options:} | |
255 | [@b{-EB}|@b{-EL}] | |
256 | [@b{-mabi}=@var{ABI}] | |
257 | @end ifset | |
258 | @ifset ALPHA | |
259 | ||
260 | @emph{Target Alpha options:} | |
261 | [@b{-m@var{cpu}}] | |
262 | [@b{-mdebug} | @b{-no-mdebug}] | |
263 | [@b{-replace} | @b{-noreplace}] | |
264 | [@b{-relax}] [@b{-g}] [@b{-G@var{size}}] | |
265 | [@b{-F}] [@b{-32addr}] | |
266 | @end ifset | |
267 | @ifset ARC | |
268 | ||
269 | @emph{Target ARC options:} | |
270 | [@b{-mcpu=@var{cpu}}] | |
271 | [@b{-mA6}|@b{-mARC600}|@b{-mARC601}|@b{-mA7}|@b{-mARC700}|@b{-mEM}|@b{-mHS}] | |
272 | [@b{-mcode-density}] | |
273 | [@b{-mrelax}] | |
274 | [@b{-EB}|@b{-EL}] | |
275 | @end ifset | |
276 | @ifset ARM | |
277 | ||
278 | @emph{Target ARM options:} | |
279 | @c Don't document the deprecated options | |
280 | [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]] | |
281 | [@b{-march}=@var{architecture}[+@var{extension}@dots{}]] | |
282 | [@b{-mfpu}=@var{floating-point-format}] | |
283 | [@b{-mfloat-abi}=@var{abi}] | |
284 | [@b{-meabi}=@var{ver}] | |
285 | [@b{-mthumb}] | |
286 | [@b{-EB}|@b{-EL}] | |
287 | [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}| | |
288 | @b{-mapcs-reentrant}] | |
289 | [@b{-mthumb-interwork}] [@b{-k}] | |
290 | @end ifset | |
291 | @ifset Blackfin | |
292 | ||
293 | @emph{Target Blackfin options:} | |
294 | [@b{-mcpu}=@var{processor}[-@var{sirevision}]] | |
295 | [@b{-mfdpic}] | |
296 | [@b{-mno-fdpic}] | |
297 | [@b{-mnopic}] | |
298 | @end ifset | |
299 | @ifset CRIS | |
300 | ||
301 | @emph{Target CRIS options:} | |
302 | [@b{--underscore} | @b{--no-underscore}] | |
303 | [@b{--pic}] [@b{-N}] | |
304 | [@b{--emulation=criself} | @b{--emulation=crisaout}] | |
305 | [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}] | |
306 | @c Deprecated -- deliberately not documented. | |
307 | @c [@b{-h}] [@b{-H}] | |
308 | @end ifset | |
309 | @ifset D10V | |
310 | ||
311 | @emph{Target D10V options:} | |
312 | [@b{-O}] | |
313 | @end ifset | |
314 | @ifset D30V | |
315 | ||
316 | @emph{Target D30V options:} | |
317 | [@b{-O}|@b{-n}|@b{-N}] | |
318 | @end ifset | |
319 | @ifset EPIPHANY | |
320 | ||
321 | @emph{Target EPIPHANY options:} | |
322 | [@b{-mepiphany}|@b{-mepiphany16}] | |
323 | @end ifset | |
324 | @ifset H8 | |
325 | ||
326 | @emph{Target H8/300 options:} | |
327 | [-h-tick-hex] | |
328 | @end ifset | |
329 | @ifset HPPA | |
330 | @c HPPA has no machine-dependent assembler options (yet). | |
331 | @end ifset | |
332 | @ifset I80386 | |
333 | ||
334 | @emph{Target i386 options:} | |
335 | [@b{--32}|@b{--x32}|@b{--64}] [@b{-n}] | |
336 | [@b{-march}=@var{CPU}[+@var{EXTENSION}@dots{}]] [@b{-mtune}=@var{CPU}] | |
337 | @end ifset | |
338 | @ifset IA64 | |
339 | ||
340 | @emph{Target IA-64 options:} | |
341 | [@b{-mconstant-gp}|@b{-mauto-pic}] | |
342 | [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}] | |
343 | [@b{-mle}|@b{mbe}] | |
344 | [@b{-mtune=itanium1}|@b{-mtune=itanium2}] | |
345 | [@b{-munwind-check=warning}|@b{-munwind-check=error}] | |
346 | [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}] | |
347 | [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}] | |
348 | @end ifset | |
349 | @ifset IP2K | |
350 | ||
351 | @emph{Target IP2K options:} | |
352 | [@b{-mip2022}|@b{-mip2022ext}] | |
353 | @end ifset | |
354 | @ifset M32C | |
355 | ||
356 | @emph{Target M32C options:} | |
357 | [@b{-m32c}|@b{-m16c}] [-relax] [-h-tick-hex] | |
358 | @end ifset | |
359 | @ifset M32R | |
360 | ||
361 | @emph{Target M32R options:} | |
362 | [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}| | |
363 | @b{--W[n]p}] | |
364 | @end ifset | |
365 | @ifset M680X0 | |
366 | ||
367 | @emph{Target M680X0 options:} | |
368 | [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}] | |
369 | @end ifset | |
370 | @ifset M68HC11 | |
371 | ||
372 | @emph{Target M68HC11 options:} | |
373 | [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}|@b{-mm9s12x}|@b{-mm9s12xg}] | |
374 | [@b{-mshort}|@b{-mlong}] | |
375 | [@b{-mshort-double}|@b{-mlong-double}] | |
376 | [@b{--force-long-branches}] [@b{--short-branches}] | |
377 | [@b{--strict-direct-mode}] [@b{--print-insn-syntax}] | |
378 | [@b{--print-opcodes}] [@b{--generate-example}] | |
379 | @end ifset | |
380 | @ifset MCORE | |
381 | ||
382 | @emph{Target MCORE options:} | |
383 | [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}] | |
384 | [@b{-mcpu=[210|340]}] | |
385 | @end ifset | |
386 | @ifset METAG | |
387 | ||
388 | @emph{Target Meta options:} | |
389 | [@b{-mcpu=@var{cpu}}] [@b{-mfpu=@var{cpu}}] [@b{-mdsp=@var{cpu}}] | |
390 | @end ifset | |
391 | @ifset MICROBLAZE | |
392 | @emph{Target MICROBLAZE options:} | |
393 | @c MicroBlaze has no machine-dependent assembler options. | |
394 | @end ifset | |
395 | @ifset MIPS | |
396 | ||
397 | @emph{Target MIPS options:} | |
398 | [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]] | |
399 | [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}] | |
400 | [@b{-non_shared}] [@b{-xgot} [@b{-mvxworks-pic}] | |
401 | [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}] | |
402 | [@b{-mfp64}] [@b{-mgp64}] [@b{-mfpxx}] | |
403 | [@b{-modd-spreg}] [@b{-mno-odd-spreg}] | |
404 | [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}] | |
405 | [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}] | |
406 | [@b{-mips32r3}] [@b{-mips32r5}] [@b{-mips32r6}] [@b{-mips64}] [@b{-mips64r2}] | |
407 | [@b{-mips64r3}] [@b{-mips64r5}] [@b{-mips64r6}] | |
408 | [@b{-construct-floats}] [@b{-no-construct-floats}] | |
409 | [@b{-mignore-branch-isa}] [@b{-mno-ignore-branch-isa}] | |
410 | [@b{-mnan=@var{encoding}}] | |
411 | [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}] | |
412 | [@b{-mips16}] [@b{-no-mips16}] | |
413 | [@b{-mmips16e2}] [@b{-mno-mips16e2}] | |
414 | [@b{-mmicromips}] [@b{-mno-micromips}] | |
415 | [@b{-msmartmips}] [@b{-mno-smartmips}] | |
416 | [@b{-mips3d}] [@b{-no-mips3d}] | |
417 | [@b{-mdmx}] [@b{-no-mdmx}] | |
418 | [@b{-mdsp}] [@b{-mno-dsp}] | |
419 | [@b{-mdspr2}] [@b{-mno-dspr2}] | |
420 | [@b{-mdspr3}] [@b{-mno-dspr3}] | |
421 | [@b{-mmsa}] [@b{-mno-msa}] | |
422 | [@b{-mxpa}] [@b{-mno-xpa}] | |
423 | [@b{-mmt}] [@b{-mno-mt}] | |
424 | [@b{-mmcu}] [@b{-mno-mcu}] | |
425 | [@b{-mcrc}] [@b{-mno-crc}] | |
426 | [@b{-mginv}] [@b{-mno-ginv}] | |
427 | [@b{-minsn32}] [@b{-mno-insn32}] | |
428 | [@b{-mfix7000}] [@b{-mno-fix7000}] | |
429 | [@b{-mfix-rm7000}] [@b{-mno-fix-rm7000}] | |
430 | [@b{-mfix-vr4120}] [@b{-mno-fix-vr4120}] | |
431 | [@b{-mfix-vr4130}] [@b{-mno-fix-vr4130}] | |
432 | [@b{-mdebug}] [@b{-no-mdebug}] | |
433 | [@b{-mpdr}] [@b{-mno-pdr}] | |
434 | @end ifset | |
435 | @ifset MMIX | |
436 | ||
437 | @emph{Target MMIX options:} | |
438 | [@b{--fixed-special-register-names}] [@b{--globalize-symbols}] | |
439 | [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}] | |
440 | [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}] | |
441 | [@b{--linker-allocated-gregs}] | |
442 | @end ifset | |
443 | @ifset NIOSII | |
444 | ||
445 | @emph{Target Nios II options:} | |
446 | [@b{-relax-all}] [@b{-relax-section}] [@b{-no-relax}] | |
447 | [@b{-EB}] [@b{-EL}] | |
448 | @end ifset | |
449 | @ifset NDS32 | |
450 | ||
451 | @emph{Target NDS32 options:} | |
452 | [@b{-EL}] [@b{-EB}] [@b{-O}] [@b{-Os}] [@b{-mcpu=@var{cpu}}] | |
453 | [@b{-misa=@var{isa}}] [@b{-mabi=@var{abi}}] [@b{-mall-ext}] | |
454 | [@b{-m[no-]16-bit}] [@b{-m[no-]perf-ext}] [@b{-m[no-]perf2-ext}] | |
455 | [@b{-m[no-]string-ext}] [@b{-m[no-]dsp-ext}] [@b{-m[no-]mac}] [@b{-m[no-]div}] | |
456 | [@b{-m[no-]audio-isa-ext}] [@b{-m[no-]fpu-sp-ext}] [@b{-m[no-]fpu-dp-ext}] | |
457 | [@b{-m[no-]fpu-fma}] [@b{-mfpu-freg=@var{FREG}}] [@b{-mreduced-regs}] | |
458 | [@b{-mfull-regs}] [@b{-m[no-]dx-regs}] [@b{-mpic}] [@b{-mno-relax}] | |
459 | [@b{-mb2bb}] | |
460 | @end ifset | |
461 | @ifset PDP11 | |
462 | ||
463 | @emph{Target PDP11 options:} | |
464 | [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}] | |
465 | [@b{-m}@var{extension}|@b{-mno-}@var{extension}] | |
466 | [@b{-m}@var{cpu}] [@b{-m}@var{machine}] | |
467 | @end ifset | |
468 | @ifset PJ | |
469 | ||
470 | @emph{Target picoJava options:} | |
471 | [@b{-mb}|@b{-me}] | |
472 | @end ifset | |
473 | @ifset PPC | |
474 | ||
475 | @emph{Target PowerPC options:} | |
476 | [@b{-a32}|@b{-a64}] | |
477 | [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|@b{-m403}|@b{-m405}| | |
478 | @b{-m440}|@b{-m464}|@b{-m476}|@b{-m7400}|@b{-m7410}|@b{-m7450}|@b{-m7455}|@b{-m750cl}|@b{-mppc64}| | |
479 | @b{-m620}|@b{-me500}|@b{-e500x2}|@b{-me500mc}|@b{-me500mc64}|@b{-me5500}|@b{-me6500}|@b{-mppc64bridge}| | |
480 | @b{-mbooke}|@b{-mpower4}|@b{-mpwr4}|@b{-mpower5}|@b{-mpwr5}|@b{-mpwr5x}|@b{-mpower6}|@b{-mpwr6}| | |
481 | @b{-mpower7}|@b{-mpwr7}|@b{-mpower8}|@b{-mpwr8}|@b{-mpower9}|@b{-mpwr9}@b{-ma2}| | |
482 | @b{-mcell}|@b{-mspe}|@b{-mspe2}|@b{-mtitan}|@b{-me300}|@b{-mcom}] | |
483 | [@b{-many}] [@b{-maltivec}|@b{-mvsx}|@b{-mhtm}|@b{-mvle}] | |
484 | [@b{-mregnames}|@b{-mno-regnames}] | |
485 | [@b{-mrelocatable}|@b{-mrelocatable-lib}|@b{-K PIC}] [@b{-memb}] | |
486 | [@b{-mlittle}|@b{-mlittle-endian}|@b{-le}|@b{-mbig}|@b{-mbig-endian}|@b{-be}] | |
487 | [@b{-msolaris}|@b{-mno-solaris}] | |
488 | [@b{-nops=@var{count}}] | |
489 | @end ifset | |
490 | @ifset PRU | |
491 | ||
492 | @emph{Target PRU options:} | |
493 | [@b{-link-relax}] | |
494 | [@b{-mnolink-relax}] | |
495 | [@b{-mno-warn-regname-label}] | |
496 | @end ifset | |
497 | @ifset RISCV | |
498 | ||
499 | @emph{Target RISC-V options:} | |
500 | [@b{-fpic}|@b{-fPIC}|@b{-fno-pic}] | |
501 | [@b{-march}=@var{ISA}] | |
502 | [@b{-mabi}=@var{ABI}] | |
503 | @end ifset | |
504 | @ifset RL78 | |
505 | ||
506 | @emph{Target RL78 options:} | |
507 | [@b{-mg10}] | |
508 | [@b{-m32bit-doubles}|@b{-m64bit-doubles}] | |
509 | @end ifset | |
510 | @ifset RX | |
511 | ||
512 | @emph{Target RX options:} | |
513 | [@b{-mlittle-endian}|@b{-mbig-endian}] | |
514 | [@b{-m32bit-doubles}|@b{-m64bit-doubles}] | |
515 | [@b{-muse-conventional-section-names}] | |
516 | [@b{-msmall-data-limit}] | |
517 | [@b{-mpid}] | |
518 | [@b{-mrelax}] | |
519 | [@b{-mint-register=@var{number}}] | |
520 | [@b{-mgcc-abi}|@b{-mrx-abi}] | |
521 | @end ifset | |
522 | @ifset S390 | |
523 | ||
524 | @emph{Target s390 options:} | |
525 | [@b{-m31}|@b{-m64}] [@b{-mesa}|@b{-mzarch}] [@b{-march}=@var{CPU}] | |
526 | [@b{-mregnames}|@b{-mno-regnames}] | |
527 | [@b{-mwarn-areg-zero}] | |
528 | @end ifset | |
529 | @ifset SCORE | |
530 | ||
531 | @emph{Target SCORE options:} | |
532 | [@b{-EB}][@b{-EL}][@b{-FIXDD}][@b{-NWARN}] | |
533 | [@b{-SCORE5}][@b{-SCORE5U}][@b{-SCORE7}][@b{-SCORE3}] | |
534 | [@b{-march=score7}][@b{-march=score3}] | |
535 | [@b{-USE_R1}][@b{-KPIC}][@b{-O0}][@b{-G} @var{num}][@b{-V}] | |
536 | @end ifset | |
537 | @ifset SPARC | |
538 | ||
539 | @emph{Target SPARC options:} | |
540 | @c The order here is important. See c-sparc.texi. | |
541 | [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Aleon}|@b{-Asparclet}|@b{-Asparclite} | |
542 | @b{-Av8plus}|@b{-Av8plusa}|@b{-Av8plusb}|@b{-Av8plusc}|@b{-Av8plusd} | |
543 | @b{-Av8plusv}|@b{-Av8plusm}|@b{-Av9}|@b{-Av9a}|@b{-Av9b}|@b{-Av9c} | |
544 | @b{-Av9d}|@b{-Av9e}|@b{-Av9v}|@b{-Av9m}|@b{-Asparc}|@b{-Asparcvis} | |
545 | @b{-Asparcvis2}|@b{-Asparcfmaf}|@b{-Asparcima}|@b{-Asparcvis3} | |
546 | @b{-Asparcvisr}|@b{-Asparc5}] | |
547 | [@b{-xarch=v8plus}|@b{-xarch=v8plusa}]|@b{-xarch=v8plusb}|@b{-xarch=v8plusc} | |
548 | @b{-xarch=v8plusd}|@b{-xarch=v8plusv}|@b{-xarch=v8plusm}|@b{-xarch=v9} | |
549 | @b{-xarch=v9a}|@b{-xarch=v9b}|@b{-xarch=v9c}|@b{-xarch=v9d}|@b{-xarch=v9e} | |
550 | @b{-xarch=v9v}|@b{-xarch=v9m}|@b{-xarch=sparc}|@b{-xarch=sparcvis} | |
551 | @b{-xarch=sparcvis2}|@b{-xarch=sparcfmaf}|@b{-xarch=sparcima} | |
552 | @b{-xarch=sparcvis3}|@b{-xarch=sparcvisr}|@b{-xarch=sparc5} | |
553 | @b{-bump}] | |
554 | [@b{-32}|@b{-64}] | |
555 | [@b{--enforce-aligned-data}][@b{--dcti-couples-detect}] | |
556 | @end ifset | |
557 | @ifset TIC54X | |
558 | ||
559 | @emph{Target TIC54X options:} | |
560 | [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}] | |
561 | [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}] | |
562 | @end ifset | |
563 | @ifset TIC6X | |
564 | ||
565 | @emph{Target TIC6X options:} | |
566 | [@b{-march=@var{arch}}] [@b{-mbig-endian}|@b{-mlittle-endian}] | |
567 | [@b{-mdsbt}|@b{-mno-dsbt}] [@b{-mpid=no}|@b{-mpid=near}|@b{-mpid=far}] | |
568 | [@b{-mpic}|@b{-mno-pic}] | |
569 | @end ifset | |
570 | @ifset TILEGX | |
571 | ||
572 | @emph{Target TILE-Gx options:} | |
573 | [@b{-m32}|@b{-m64}][@b{-EB}][@b{-EL}] | |
574 | @end ifset | |
575 | @ifset TILEPRO | |
576 | @c TILEPro has no machine-dependent assembler options | |
577 | @end ifset | |
578 | @ifset VISIUM | |
579 | ||
580 | @emph{Target Visium options:} | |
581 | [@b{-mtune=@var{arch}}] | |
582 | @end ifset | |
583 | @ifset XTENSA | |
584 | ||
585 | @emph{Target Xtensa options:} | |
586 | [@b{--[no-]text-section-literals}] [@b{--[no-]auto-litpools}] | |
587 | [@b{--[no-]absolute-literals}] | |
588 | [@b{--[no-]target-align}] [@b{--[no-]longcalls}] | |
589 | [@b{--[no-]transform}] | |
590 | [@b{--rename-section} @var{oldname}=@var{newname}] | |
591 | [@b{--[no-]trampolines}] | |
592 | @end ifset | |
593 | @ifset Z80 | |
594 | ||
595 | @emph{Target Z80 options:} | |
596 | [@b{-z80}] [@b{-r800}] | |
597 | [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}] | |
598 | [@b{ -ignore-unportable-instructions}] [@b{-Wnup}] | |
599 | [@b{ -warn-undocumented-instructions}] [@b{-Wud}] | |
600 | [@b{ -warn-unportable-instructions}] [@b{-Wup}] | |
601 | [@b{ -forbid-undocumented-instructions}] [@b{-Fud}] | |
602 | [@b{ -forbid-unportable-instructions}] [@b{-Fup}] | |
603 | @end ifset | |
604 | @ifset Z8000 | |
605 | ||
606 | @c Z8000 has no machine-dependent assembler options | |
607 | @end ifset | |
608 | ||
609 | @c man end | |
610 | @end smallexample | |
611 | ||
612 | @c man begin OPTIONS | |
613 | ||
614 | @table @gcctabopt | |
615 | @include at-file.texi | |
616 | ||
617 | @item -a[cdghlmns] | |
618 | Turn on listings, in any of a variety of ways: | |
619 | ||
620 | @table @gcctabopt | |
621 | @item -ac | |
622 | omit false conditionals | |
623 | ||
624 | @item -ad | |
625 | omit debugging directives | |
626 | ||
627 | @item -ag | |
628 | include general information, like @value{AS} version and options passed | |
629 | ||
630 | @item -ah | |
631 | include high-level source | |
632 | ||
633 | @item -al | |
634 | include assembly | |
635 | ||
636 | @item -am | |
637 | include macro expansions | |
638 | ||
639 | @item -an | |
640 | omit forms processing | |
641 | ||
642 | @item -as | |
643 | include symbols | |
644 | ||
645 | @item =file | |
646 | set the name of the listing file | |
647 | @end table | |
648 | ||
649 | You may combine these options; for example, use @samp{-aln} for assembly | |
650 | listing without forms processing. The @samp{=file} option, if used, must be | |
651 | the last one. By itself, @samp{-a} defaults to @samp{-ahls}. | |
652 | ||
653 | @item --alternate | |
654 | Begin in alternate macro mode. | |
655 | @ifclear man | |
656 | @xref{Altmacro,,@code{.altmacro}}. | |
657 | @end ifclear | |
658 | ||
659 | @item --compress-debug-sections | |
660 | Compress DWARF debug sections using zlib with SHF_COMPRESSED from the | |
661 | ELF ABI. The resulting object file may not be compatible with older | |
662 | linkers and object file utilities. Note if compression would make a | |
663 | given section @emph{larger} then it is not compressed. | |
664 | ||
665 | @ifset ELF | |
666 | @cindex @samp{--compress-debug-sections=} option | |
667 | @item --compress-debug-sections=none | |
668 | @itemx --compress-debug-sections=zlib | |
669 | @itemx --compress-debug-sections=zlib-gnu | |
670 | @itemx --compress-debug-sections=zlib-gabi | |
671 | These options control how DWARF debug sections are compressed. | |
672 | @option{--compress-debug-sections=none} is equivalent to | |
673 | @option{--nocompress-debug-sections}. | |
674 | @option{--compress-debug-sections=zlib} and | |
675 | @option{--compress-debug-sections=zlib-gabi} are equivalent to | |
676 | @option{--compress-debug-sections}. | |
677 | @option{--compress-debug-sections=zlib-gnu} compresses DWARF debug | |
678 | sections using zlib. The debug sections are renamed to begin with | |
679 | @samp{.zdebug}. Note if compression would make a given section | |
680 | @emph{larger} then it is not compressed nor renamed. | |
681 | ||
682 | @end ifset | |
683 | ||
684 | @item --nocompress-debug-sections | |
685 | Do not compress DWARF debug sections. This is usually the default for all | |
686 | targets except the x86/x86_64, but a configure time option can be used to | |
687 | override this. | |
688 | ||
689 | @item -D | |
690 | Ignored. This option is accepted for script compatibility with calls to | |
691 | other assemblers. | |
692 | ||
693 | @item --debug-prefix-map @var{old}=@var{new} | |
694 | When assembling files in directory @file{@var{old}}, record debugging | |
695 | information describing them as in @file{@var{new}} instead. | |
696 | ||
697 | @item --defsym @var{sym}=@var{value} | |
698 | Define the symbol @var{sym} to be @var{value} before assembling the input file. | |
699 | @var{value} must be an integer constant. As in C, a leading @samp{0x} | |
700 | indicates a hexadecimal value, and a leading @samp{0} indicates an octal | |
701 | value. The value of the symbol can be overridden inside a source file via the | |
702 | use of a @code{.set} pseudo-op. | |
703 | ||
704 | @item -f | |
705 | ``fast''---skip whitespace and comment preprocessing (assume source is | |
706 | compiler output). | |
707 | ||
708 | @item -g | |
709 | @itemx --gen-debug | |
710 | Generate debugging information for each assembler source line using whichever | |
711 | debug format is preferred by the target. This currently means either STABS, | |
712 | ECOFF or DWARF2. | |
713 | ||
714 | @item --gstabs | |
715 | Generate stabs debugging information for each assembler line. This | |
716 | may help debugging assembler code, if the debugger can handle it. | |
717 | ||
718 | @item --gstabs+ | |
719 | Generate stabs debugging information for each assembler line, with GNU | |
720 | extensions that probably only gdb can handle, and that could make other | |
721 | debuggers crash or refuse to read your program. This | |
722 | may help debugging assembler code. Currently the only GNU extension is | |
723 | the location of the current working directory at assembling time. | |
724 | ||
725 | @item --gdwarf-2 | |
726 | Generate DWARF2 debugging information for each assembler line. This | |
727 | may help debugging assembler code, if the debugger can handle it. Note---this | |
728 | option is only supported by some targets, not all of them. | |
729 | ||
730 | @item --gdwarf-sections | |
731 | Instead of creating a .debug_line section, create a series of | |
732 | .debug_line.@var{foo} sections where @var{foo} is the name of the | |
733 | corresponding code section. For example a code section called @var{.text.func} | |
734 | will have its dwarf line number information placed into a section called | |
735 | @var{.debug_line.text.func}. If the code section is just called @var{.text} | |
736 | then debug line section will still be called just @var{.debug_line} without any | |
737 | suffix. | |
738 | ||
739 | @ifset ELF | |
740 | @item --size-check=error | |
741 | @itemx --size-check=warning | |
742 | Issue an error or warning for invalid ELF .size directive. | |
743 | ||
744 | @item --elf-stt-common=no | |
745 | @itemx --elf-stt-common=yes | |
746 | These options control whether the ELF assembler should generate common | |
747 | symbols with the @code{STT_COMMON} type. The default can be controlled | |
748 | by a configure option @option{--enable-elf-stt-common}. | |
749 | ||
750 | @item --generate-missing-build-notes=yes | |
751 | @itemx --generate-missing-build-notes=no | |
752 | These options control whether the ELF assembler should generate GNU Build | |
753 | attribute notes if none are present in the input sources. | |
754 | The default can be controlled by the @option{--enable-generate-build-notes} | |
755 | configure option. | |
756 | ||
757 | @end ifset | |
758 | ||
759 | @item --help | |
760 | Print a summary of the command line options and exit. | |
761 | ||
762 | @item --target-help | |
763 | Print a summary of all target specific options and exit. | |
764 | ||
765 | @item -I @var{dir} | |
766 | Add directory @var{dir} to the search list for @code{.include} directives. | |
767 | ||
768 | @item -J | |
769 | Don't warn about signed overflow. | |
770 | ||
771 | @item -K | |
772 | @ifclear DIFF-TBL-KLUGE | |
773 | This option is accepted but has no effect on the @value{TARGET} family. | |
774 | @end ifclear | |
775 | @ifset DIFF-TBL-KLUGE | |
776 | Issue warnings when difference tables altered for long displacements. | |
777 | @end ifset | |
778 | ||
779 | @item -L | |
780 | @itemx --keep-locals | |
781 | Keep (in the symbol table) local symbols. These symbols start with | |
782 | system-specific local label prefixes, typically @samp{.L} for ELF systems | |
783 | or @samp{L} for traditional a.out systems. | |
784 | @ifclear man | |
785 | @xref{Symbol Names}. | |
786 | @end ifclear | |
787 | ||
788 | @item --listing-lhs-width=@var{number} | |
789 | Set the maximum width, in words, of the output data column for an assembler | |
790 | listing to @var{number}. | |
791 | ||
792 | @item --listing-lhs-width2=@var{number} | |
793 | Set the maximum width, in words, of the output data column for continuation | |
794 | lines in an assembler listing to @var{number}. | |
795 | ||
796 | @item --listing-rhs-width=@var{number} | |
797 | Set the maximum width of an input source line, as displayed in a listing, to | |
798 | @var{number} bytes. | |
799 | ||
800 | @item --listing-cont-lines=@var{number} | |
801 | Set the maximum number of lines printed in a listing for a single line of input | |
802 | to @var{number} + 1. | |
803 | ||
804 | @item --no-pad-sections | |
805 | Stop the assembler for padding the ends of output sections to the alignment | |
806 | of that section. The default is to pad the sections, but this can waste space | |
807 | which might be needed on targets which have tight memory constraints. | |
808 | ||
809 | @item -o @var{objfile} | |
810 | Name the object-file output from @command{@value{AS}} @var{objfile}. | |
811 | ||
812 | @item -R | |
813 | Fold the data section into the text section. | |
814 | ||
815 | @item --hash-size=@var{number} | |
816 | Set the default size of GAS's hash tables to a prime number close to | |
817 | @var{number}. Increasing this value can reduce the length of time it takes the | |
818 | assembler to perform its tasks, at the expense of increasing the assembler's | |
819 | memory requirements. Similarly reducing this value can reduce the memory | |
820 | requirements at the expense of speed. | |
821 | ||
822 | @item --reduce-memory-overheads | |
823 | This option reduces GAS's memory requirements, at the expense of making the | |
824 | assembly processes slower. Currently this switch is a synonym for | |
825 | @samp{--hash-size=4051}, but in the future it may have other effects as well. | |
826 | ||
827 | @ifset ELF | |
828 | @item --sectname-subst | |
829 | Honor substitution sequences in section names. | |
830 | @ifclear man | |
831 | @xref{Section Name Substitutions,,@code{.section @var{name}}}. | |
832 | @end ifclear | |
833 | @end ifset | |
834 | ||
835 | @item --statistics | |
836 | Print the maximum space (in bytes) and total time (in seconds) used by | |
837 | assembly. | |
838 | ||
839 | @item --strip-local-absolute | |
840 | Remove local absolute symbols from the outgoing symbol table. | |
841 | ||
842 | @item -v | |
843 | @itemx -version | |
844 | Print the @command{as} version. | |
845 | ||
846 | @item --version | |
847 | Print the @command{as} version and exit. | |
848 | ||
849 | @item -W | |
850 | @itemx --no-warn | |
851 | Suppress warning messages. | |
852 | ||
853 | @item --fatal-warnings | |
854 | Treat warnings as errors. | |
855 | ||
856 | @item --warn | |
857 | Don't suppress warning messages or treat them as errors. | |
858 | ||
859 | @item -w | |
860 | Ignored. | |
861 | ||
862 | @item -x | |
863 | Ignored. | |
864 | ||
865 | @item -Z | |
866 | Generate an object file even after errors. | |
867 | ||
868 | @item -- | @var{files} @dots{} | |
869 | Standard input, or source files to assemble. | |
870 | ||
871 | @end table | |
872 | @c man end | |
873 | ||
874 | @ifset AARCH64 | |
875 | ||
876 | @ifclear man | |
877 | @xref{AArch64 Options}, for the options available when @value{AS} is configured | |
878 | for the 64-bit mode of the ARM Architecture (AArch64). | |
879 | @end ifclear | |
880 | ||
881 | @ifset man | |
882 | @c man begin OPTIONS | |
883 | The following options are available when @value{AS} is configured for the | |
884 | 64-bit mode of the ARM Architecture (AArch64). | |
885 | @c man end | |
886 | @c man begin INCLUDE | |
887 | @include c-aarch64.texi | |
888 | @c ended inside the included file | |
889 | @end ifset | |
890 | ||
891 | @end ifset | |
892 | ||
893 | @ifset ALPHA | |
894 | ||
895 | @ifclear man | |
896 | @xref{Alpha Options}, for the options available when @value{AS} is configured | |
897 | for an Alpha processor. | |
898 | @end ifclear | |
899 | ||
900 | @ifset man | |
901 | @c man begin OPTIONS | |
902 | The following options are available when @value{AS} is configured for an Alpha | |
903 | processor. | |
904 | @c man end | |
905 | @c man begin INCLUDE | |
906 | @include c-alpha.texi | |
907 | @c ended inside the included file | |
908 | @end ifset | |
909 | ||
910 | @end ifset | |
911 | ||
912 | @c man begin OPTIONS | |
913 | @ifset ARC | |
914 | The following options are available when @value{AS} is configured for an ARC | |
915 | processor. | |
916 | ||
917 | @table @gcctabopt | |
918 | @item -mcpu=@var{cpu} | |
919 | This option selects the core processor variant. | |
920 | @item -EB | -EL | |
921 | Select either big-endian (-EB) or little-endian (-EL) output. | |
922 | @item -mcode-density | |
923 | Enable Code Density extenssion instructions. | |
924 | @end table | |
925 | @end ifset | |
926 | ||
927 | @ifset ARM | |
928 | The following options are available when @value{AS} is configured for the ARM | |
929 | processor family. | |
930 | ||
931 | @table @gcctabopt | |
932 | @item -mcpu=@var{processor}[+@var{extension}@dots{}] | |
933 | Specify which ARM processor variant is the target. | |
934 | @item -march=@var{architecture}[+@var{extension}@dots{}] | |
935 | Specify which ARM architecture variant is used by the target. | |
936 | @item -mfpu=@var{floating-point-format} | |
937 | Select which Floating Point architecture is the target. | |
938 | @item -mfloat-abi=@var{abi} | |
939 | Select which floating point ABI is in use. | |
940 | @item -mthumb | |
941 | Enable Thumb only instruction decoding. | |
942 | @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | |
943 | Select which procedure calling convention is in use. | |
944 | @item -EB | -EL | |
945 | Select either big-endian (-EB) or little-endian (-EL) output. | |
946 | @item -mthumb-interwork | |
947 | Specify that the code has been generated with interworking between Thumb and | |
948 | ARM code in mind. | |
949 | @item -mccs | |
950 | Turns on CodeComposer Studio assembly syntax compatibility mode. | |
951 | @item -k | |
952 | Specify that PIC code has been generated. | |
953 | @end table | |
954 | @end ifset | |
955 | @c man end | |
956 | ||
957 | @ifset Blackfin | |
958 | ||
959 | @ifclear man | |
960 | @xref{Blackfin Options}, for the options available when @value{AS} is | |
961 | configured for the Blackfin processor family. | |
962 | @end ifclear | |
963 | ||
964 | @ifset man | |
965 | @c man begin OPTIONS | |
966 | The following options are available when @value{AS} is configured for | |
967 | the Blackfin processor family. | |
968 | @c man end | |
969 | @c man begin INCLUDE | |
970 | @include c-bfin.texi | |
971 | @c ended inside the included file | |
972 | @end ifset | |
973 | ||
974 | @end ifset | |
975 | ||
976 | @c man begin OPTIONS | |
977 | @ifset CRIS | |
978 | See the info pages for documentation of the CRIS-specific options. | |
979 | @end ifset | |
980 | ||
981 | @ifset D10V | |
982 | The following options are available when @value{AS} is configured for | |
983 | a D10V processor. | |
984 | @table @gcctabopt | |
985 | @cindex D10V optimization | |
986 | @cindex optimization, D10V | |
987 | @item -O | |
988 | Optimize output by parallelizing instructions. | |
989 | @end table | |
990 | @end ifset | |
991 | ||
992 | @ifset D30V | |
993 | The following options are available when @value{AS} is configured for a D30V | |
994 | processor. | |
995 | @table @gcctabopt | |
996 | @cindex D30V optimization | |
997 | @cindex optimization, D30V | |
998 | @item -O | |
999 | Optimize output by parallelizing instructions. | |
1000 | ||
1001 | @cindex D30V nops | |
1002 | @item -n | |
1003 | Warn when nops are generated. | |
1004 | ||
1005 | @cindex D30V nops after 32-bit multiply | |
1006 | @item -N | |
1007 | Warn when a nop after a 32-bit multiply instruction is generated. | |
1008 | @end table | |
1009 | @end ifset | |
1010 | @c man end | |
1011 | ||
1012 | @ifset EPIPHANY | |
1013 | The following options are available when @value{AS} is configured for the | |
1014 | Adapteva EPIPHANY series. | |
1015 | ||
1016 | @ifclear man | |
1017 | @xref{Epiphany Options}, for the options available when @value{AS} is | |
1018 | configured for an Epiphany processor. | |
1019 | @end ifclear | |
1020 | ||
1021 | @ifset man | |
1022 | @c man begin OPTIONS | |
1023 | The following options are available when @value{AS} is configured for | |
1024 | an Epiphany processor. | |
1025 | @c man end | |
1026 | @c man begin INCLUDE | |
1027 | @include c-epiphany.texi | |
1028 | @c ended inside the included file | |
1029 | @end ifset | |
1030 | ||
1031 | @end ifset | |
1032 | ||
1033 | @ifset H8300 | |
1034 | ||
1035 | @ifclear man | |
1036 | @xref{H8/300 Options}, for the options available when @value{AS} is configured | |
1037 | for an H8/300 processor. | |
1038 | @end ifclear | |
1039 | ||
1040 | @ifset man | |
1041 | @c man begin OPTIONS | |
1042 | The following options are available when @value{AS} is configured for an H8/300 | |
1043 | processor. | |
1044 | @c man end | |
1045 | @c man begin INCLUDE | |
1046 | @include c-h8300.texi | |
1047 | @c ended inside the included file | |
1048 | @end ifset | |
1049 | ||
1050 | @end ifset | |
1051 | ||
1052 | @ifset I80386 | |
1053 | ||
1054 | @ifclear man | |
1055 | @xref{i386-Options}, for the options available when @value{AS} is | |
1056 | configured for an i386 processor. | |
1057 | @end ifclear | |
1058 | ||
1059 | @ifset man | |
1060 | @c man begin OPTIONS | |
1061 | The following options are available when @value{AS} is configured for | |
1062 | an i386 processor. | |
1063 | @c man end | |
1064 | @c man begin INCLUDE | |
1065 | @include c-i386.texi | |
1066 | @c ended inside the included file | |
1067 | @end ifset | |
1068 | ||
1069 | @end ifset | |
1070 | ||
1071 | @c man begin OPTIONS | |
1072 | @ifset IP2K | |
1073 | The following options are available when @value{AS} is configured for the | |
1074 | Ubicom IP2K series. | |
1075 | ||
1076 | @table @gcctabopt | |
1077 | ||
1078 | @item -mip2022ext | |
1079 | Specifies that the extended IP2022 instructions are allowed. | |
1080 | ||
1081 | @item -mip2022 | |
1082 | Restores the default behaviour, which restricts the permitted instructions to | |
1083 | just the basic IP2022 ones. | |
1084 | ||
1085 | @end table | |
1086 | @end ifset | |
1087 | ||
1088 | @ifset M32C | |
1089 | The following options are available when @value{AS} is configured for the | |
1090 | Renesas M32C and M16C processors. | |
1091 | ||
1092 | @table @gcctabopt | |
1093 | ||
1094 | @item -m32c | |
1095 | Assemble M32C instructions. | |
1096 | ||
1097 | @item -m16c | |
1098 | Assemble M16C instructions (the default). | |
1099 | ||
1100 | @item -relax | |
1101 | Enable support for link-time relaxations. | |
1102 | ||
1103 | @item -h-tick-hex | |
1104 | Support H'00 style hex constants in addition to 0x00 style. | |
1105 | ||
1106 | @end table | |
1107 | @end ifset | |
1108 | ||
1109 | @ifset M32R | |
1110 | The following options are available when @value{AS} is configured for the | |
1111 | Renesas M32R (formerly Mitsubishi M32R) series. | |
1112 | ||
1113 | @table @gcctabopt | |
1114 | ||
1115 | @item --m32rx | |
1116 | Specify which processor in the M32R family is the target. The default | |
1117 | is normally the M32R, but this option changes it to the M32RX. | |
1118 | ||
1119 | @item --warn-explicit-parallel-conflicts or --Wp | |
1120 | Produce warning messages when questionable parallel constructs are | |
1121 | encountered. | |
1122 | ||
1123 | @item --no-warn-explicit-parallel-conflicts or --Wnp | |
1124 | Do not produce warning messages when questionable parallel constructs are | |
1125 | encountered. | |
1126 | ||
1127 | @end table | |
1128 | @end ifset | |
1129 | ||
1130 | @ifset M680X0 | |
1131 | The following options are available when @value{AS} is configured for the | |
1132 | Motorola 68000 series. | |
1133 | ||
1134 | @table @gcctabopt | |
1135 | ||
1136 | @item -l | |
1137 | Shorten references to undefined symbols, to one word instead of two. | |
1138 | ||
1139 | @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 | |
1140 | @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332 | |
1141 | @itemx | -m68333 | -m68340 | -mcpu32 | -m5200 | |
1142 | Specify what processor in the 68000 family is the target. The default | |
1143 | is normally the 68020, but this can be changed at configuration time. | |
1144 | ||
1145 | @item -m68881 | -m68882 | -mno-68881 | -mno-68882 | |
1146 | The target machine does (or does not) have a floating-point coprocessor. | |
1147 | The default is to assume a coprocessor for 68020, 68030, and cpu32. Although | |
1148 | the basic 68000 is not compatible with the 68881, a combination of the | |
1149 | two can be specified, since it's possible to do emulation of the | |
1150 | coprocessor instructions with the main processor. | |
1151 | ||
1152 | @item -m68851 | -mno-68851 | |
1153 | The target machine does (or does not) have a memory-management | |
1154 | unit coprocessor. The default is to assume an MMU for 68020 and up. | |
1155 | ||
1156 | @end table | |
1157 | @end ifset | |
1158 | ||
1159 | @ifset NIOSII | |
1160 | ||
1161 | @ifclear man | |
1162 | @xref{Nios II Options}, for the options available when @value{AS} is configured | |
1163 | for an Altera Nios II processor. | |
1164 | @end ifclear | |
1165 | ||
1166 | @ifset man | |
1167 | @c man begin OPTIONS | |
1168 | The following options are available when @value{AS} is configured for an | |
1169 | Altera Nios II processor. | |
1170 | @c man end | |
1171 | @c man begin INCLUDE | |
1172 | @include c-nios2.texi | |
1173 | @c ended inside the included file | |
1174 | @end ifset | |
1175 | @end ifset | |
1176 | ||
1177 | @ifset PDP11 | |
1178 | ||
1179 | For details about the PDP-11 machine dependent features options, | |
1180 | see @ref{PDP-11-Options}. | |
1181 | ||
1182 | @table @gcctabopt | |
1183 | @item -mpic | -mno-pic | |
1184 | Generate position-independent (or position-dependent) code. The | |
1185 | default is @option{-mpic}. | |
1186 | ||
1187 | @item -mall | |
1188 | @itemx -mall-extensions | |
1189 | Enable all instruction set extensions. This is the default. | |
1190 | ||
1191 | @item -mno-extensions | |
1192 | Disable all instruction set extensions. | |
1193 | ||
1194 | @item -m@var{extension} | -mno-@var{extension} | |
1195 | Enable (or disable) a particular instruction set extension. | |
1196 | ||
1197 | @item -m@var{cpu} | |
1198 | Enable the instruction set extensions supported by a particular CPU, and | |
1199 | disable all other extensions. | |
1200 | ||
1201 | @item -m@var{machine} | |
1202 | Enable the instruction set extensions supported by a particular machine | |
1203 | model, and disable all other extensions. | |
1204 | @end table | |
1205 | ||
1206 | @end ifset | |
1207 | ||
1208 | @ifset PJ | |
1209 | The following options are available when @value{AS} is configured for | |
1210 | a picoJava processor. | |
1211 | ||
1212 | @table @gcctabopt | |
1213 | ||
1214 | @cindex PJ endianness | |
1215 | @cindex endianness, PJ | |
1216 | @cindex big endian output, PJ | |
1217 | @item -mb | |
1218 | Generate ``big endian'' format output. | |
1219 | ||
1220 | @cindex little endian output, PJ | |
1221 | @item -ml | |
1222 | Generate ``little endian'' format output. | |
1223 | ||
1224 | @end table | |
1225 | @end ifset | |
1226 | ||
1227 | @ifset PRU | |
1228 | ||
1229 | @ifclear man | |
1230 | @xref{PRU Options}, for the options available when @value{AS} is configured | |
1231 | for a PRU processor. | |
1232 | @end ifclear | |
1233 | ||
1234 | @ifset man | |
1235 | @c man begin OPTIONS | |
1236 | The following options are available when @value{AS} is configured for a | |
1237 | PRU processor. | |
1238 | @c man end | |
1239 | @c man begin INCLUDE | |
1240 | @include c-pru.texi | |
1241 | @c ended inside the included file | |
1242 | @end ifset | |
1243 | @end ifset | |
1244 | ||
1245 | @ifset M68HC11 | |
1246 | The following options are available when @value{AS} is configured for the | |
1247 | Motorola 68HC11 or 68HC12 series. | |
1248 | ||
1249 | @table @gcctabopt | |
1250 | ||
1251 | @item -m68hc11 | -m68hc12 | -m68hcs12 | -mm9s12x | -mm9s12xg | |
1252 | Specify what processor is the target. The default is | |
1253 | defined by the configuration option when building the assembler. | |
1254 | ||
1255 | @item --xgate-ramoffset | |
1256 | Instruct the linker to offset RAM addresses from S12X address space into | |
1257 | XGATE address space. | |
1258 | ||
1259 | @item -mshort | |
1260 | Specify to use the 16-bit integer ABI. | |
1261 | ||
1262 | @item -mlong | |
1263 | Specify to use the 32-bit integer ABI. | |
1264 | ||
1265 | @item -mshort-double | |
1266 | Specify to use the 32-bit double ABI. | |
1267 | ||
1268 | @item -mlong-double | |
1269 | Specify to use the 64-bit double ABI. | |
1270 | ||
1271 | @item --force-long-branches | |
1272 | Relative branches are turned into absolute ones. This concerns | |
1273 | conditional branches, unconditional branches and branches to a | |
1274 | sub routine. | |
1275 | ||
1276 | @item -S | --short-branches | |
1277 | Do not turn relative branches into absolute ones | |
1278 | when the offset is out of range. | |
1279 | ||
1280 | @item --strict-direct-mode | |
1281 | Do not turn the direct addressing mode into extended addressing mode | |
1282 | when the instruction does not support direct addressing mode. | |
1283 | ||
1284 | @item --print-insn-syntax | |
1285 | Print the syntax of instruction in case of error. | |
1286 | ||
1287 | @item --print-opcodes | |
1288 | Print the list of instructions with syntax and then exit. | |
1289 | ||
1290 | @item --generate-example | |
1291 | Print an example of instruction for each possible instruction and then exit. | |
1292 | This option is only useful for testing @command{@value{AS}}. | |
1293 | ||
1294 | @end table | |
1295 | @end ifset | |
1296 | ||
1297 | @ifset SPARC | |
1298 | The following options are available when @command{@value{AS}} is configured | |
1299 | for the SPARC architecture: | |
1300 | ||
1301 | @table @gcctabopt | |
1302 | @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite | |
1303 | @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a | |
1304 | Explicitly select a variant of the SPARC architecture. | |
1305 | ||
1306 | @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment. | |
1307 | @samp{-Av9} and @samp{-Av9a} select a 64 bit environment. | |
1308 | ||
1309 | @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with | |
1310 | UltraSPARC extensions. | |
1311 | ||
1312 | @item -xarch=v8plus | -xarch=v8plusa | |
1313 | For compatibility with the Solaris v9 assembler. These options are | |
1314 | equivalent to -Av8plus and -Av8plusa, respectively. | |
1315 | ||
1316 | @item -bump | |
1317 | Warn when the assembler switches to another architecture. | |
1318 | @end table | |
1319 | @end ifset | |
1320 | ||
1321 | @ifset TIC54X | |
1322 | The following options are available when @value{AS} is configured for the 'c54x | |
1323 | architecture. | |
1324 | ||
1325 | @table @gcctabopt | |
1326 | @item -mfar-mode | |
1327 | Enable extended addressing mode. All addresses and relocations will assume | |
1328 | extended addressing (usually 23 bits). | |
1329 | @item -mcpu=@var{CPU_VERSION} | |
1330 | Sets the CPU version being compiled for. | |
1331 | @item -merrors-to-file @var{FILENAME} | |
1332 | Redirect error output to a file, for broken systems which don't support such | |
1333 | behaviour in the shell. | |
1334 | @end table | |
1335 | @end ifset | |
1336 | ||
1337 | @ifset MIPS | |
1338 | @c man begin OPTIONS | |
1339 | The following options are available when @value{AS} is configured for | |
1340 | a MIPS processor. | |
1341 | ||
1342 | @table @gcctabopt | |
1343 | @item -G @var{num} | |
1344 | This option sets the largest size of an object that can be referenced | |
1345 | implicitly with the @code{gp} register. It is only accepted for targets that | |
1346 | use ECOFF format, such as a DECstation running Ultrix. The default value is 8. | |
1347 | ||
1348 | @cindex MIPS endianness | |
1349 | @cindex endianness, MIPS | |
1350 | @cindex big endian output, MIPS | |
1351 | @item -EB | |
1352 | Generate ``big endian'' format output. | |
1353 | ||
1354 | @cindex little endian output, MIPS | |
1355 | @item -EL | |
1356 | Generate ``little endian'' format output. | |
1357 | ||
1358 | @cindex MIPS ISA | |
1359 | @item -mips1 | |
1360 | @itemx -mips2 | |
1361 | @itemx -mips3 | |
1362 | @itemx -mips4 | |
1363 | @itemx -mips5 | |
1364 | @itemx -mips32 | |
1365 | @itemx -mips32r2 | |
1366 | @itemx -mips32r3 | |
1367 | @itemx -mips32r5 | |
1368 | @itemx -mips32r6 | |
1369 | @itemx -mips64 | |
1370 | @itemx -mips64r2 | |
1371 | @itemx -mips64r3 | |
1372 | @itemx -mips64r5 | |
1373 | @itemx -mips64r6 | |
1374 | Generate code for a particular MIPS Instruction Set Architecture level. | |
1375 | @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an | |
1376 | alias for @samp{-march=r6000}, @samp{-mips3} is an alias for | |
1377 | @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}. | |
1378 | @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips32r3}, | |
1379 | @samp{-mips32r5}, @samp{-mips32r6}, @samp{-mips64}, @samp{-mips64r2}, | |
1380 | @samp{-mips64r3}, @samp{-mips64r5}, and @samp{-mips64r6} correspond to generic | |
1381 | MIPS V, MIPS32, MIPS32 Release 2, MIPS32 Release 3, MIPS32 Release 5, MIPS32 | |
1382 | Release 6, MIPS64, MIPS64 Release 2, MIPS64 Release 3, MIPS64 Release 5, and | |
1383 | MIPS64 Release 6 ISA processors, respectively. | |
1384 | ||
1385 | @item -march=@var{cpu} | |
1386 | Generate code for a particular MIPS CPU. | |
1387 | ||
1388 | @item -mtune=@var{cpu} | |
1389 | Schedule and tune for a particular MIPS CPU. | |
1390 | ||
1391 | @item -mfix7000 | |
1392 | @itemx -mno-fix7000 | |
1393 | Cause nops to be inserted if the read of the destination register | |
1394 | of an mfhi or mflo instruction occurs in the following two instructions. | |
1395 | ||
1396 | @item -mfix-rm7000 | |
1397 | @itemx -mno-fix-rm7000 | |
1398 | Cause nops to be inserted if a dmult or dmultu instruction is | |
1399 | followed by a load instruction. | |
1400 | ||
1401 | @item -mdebug | |
1402 | @itemx -no-mdebug | |
1403 | Cause stabs-style debugging output to go into an ECOFF-style .mdebug | |
1404 | section instead of the standard ELF .stabs sections. | |
1405 | ||
1406 | @item -mpdr | |
1407 | @itemx -mno-pdr | |
1408 | Control generation of @code{.pdr} sections. | |
1409 | ||
1410 | @item -mgp32 | |
1411 | @itemx -mfp32 | |
1412 | The register sizes are normally inferred from the ISA and ABI, but these | |
1413 | flags force a certain group of registers to be treated as 32 bits wide at | |
1414 | all times. @samp{-mgp32} controls the size of general-purpose registers | |
1415 | and @samp{-mfp32} controls the size of floating-point registers. | |
1416 | ||
1417 | @item -mgp64 | |
1418 | @itemx -mfp64 | |
1419 | The register sizes are normally inferred from the ISA and ABI, but these | |
1420 | flags force a certain group of registers to be treated as 64 bits wide at | |
1421 | all times. @samp{-mgp64} controls the size of general-purpose registers | |
1422 | and @samp{-mfp64} controls the size of floating-point registers. | |
1423 | ||
1424 | @item -mfpxx | |
1425 | The register sizes are normally inferred from the ISA and ABI, but using | |
1426 | this flag in combination with @samp{-mabi=32} enables an ABI variant | |
1427 | which will operate correctly with floating-point registers which are | |
1428 | 32 or 64 bits wide. | |
1429 | ||
1430 | @item -modd-spreg | |
1431 | @itemx -mno-odd-spreg | |
1432 | Enable use of floating-point operations on odd-numbered single-precision | |
1433 | registers when supported by the ISA. @samp{-mfpxx} implies | |
1434 | @samp{-mno-odd-spreg}, otherwise the default is @samp{-modd-spreg}. | |
1435 | ||
1436 | @item -mips16 | |
1437 | @itemx -no-mips16 | |
1438 | Generate code for the MIPS 16 processor. This is equivalent to putting | |
1439 | @code{.module mips16} at the start of the assembly file. @samp{-no-mips16} | |
1440 | turns off this option. | |
1441 | ||
1442 | @item -mmips16e2 | |
1443 | @itemx -mno-mips16e2 | |
1444 | Enable the use of MIPS16e2 instructions in MIPS16 mode. This is equivalent | |
1445 | to putting @code{.module mips16e2} at the start of the assembly file. | |
1446 | @samp{-mno-mips16e2} turns off this option. | |
1447 | ||
1448 | @item -mmicromips | |
1449 | @itemx -mno-micromips | |
1450 | Generate code for the microMIPS processor. This is equivalent to putting | |
1451 | @code{.module micromips} at the start of the assembly file. | |
1452 | @samp{-mno-micromips} turns off this option. This is equivalent to putting | |
1453 | @code{.module nomicromips} at the start of the assembly file. | |
1454 | ||
1455 | @item -msmartmips | |
1456 | @itemx -mno-smartmips | |
1457 | Enables the SmartMIPS extension to the MIPS32 instruction set. This is | |
1458 | equivalent to putting @code{.module smartmips} at the start of the assembly | |
1459 | file. @samp{-mno-smartmips} turns off this option. | |
1460 | ||
1461 | @item -mips3d | |
1462 | @itemx -no-mips3d | |
1463 | Generate code for the MIPS-3D Application Specific Extension. | |
1464 | This tells the assembler to accept MIPS-3D instructions. | |
1465 | @samp{-no-mips3d} turns off this option. | |
1466 | ||
1467 | @item -mdmx | |
1468 | @itemx -no-mdmx | |
1469 | Generate code for the MDMX Application Specific Extension. | |
1470 | This tells the assembler to accept MDMX instructions. | |
1471 | @samp{-no-mdmx} turns off this option. | |
1472 | ||
1473 | @item -mdsp | |
1474 | @itemx -mno-dsp | |
1475 | Generate code for the DSP Release 1 Application Specific Extension. | |
1476 | This tells the assembler to accept DSP Release 1 instructions. | |
1477 | @samp{-mno-dsp} turns off this option. | |
1478 | ||
1479 | @item -mdspr2 | |
1480 | @itemx -mno-dspr2 | |
1481 | Generate code for the DSP Release 2 Application Specific Extension. | |
1482 | This option implies @samp{-mdsp}. | |
1483 | This tells the assembler to accept DSP Release 2 instructions. | |
1484 | @samp{-mno-dspr2} turns off this option. | |
1485 | ||
1486 | @item -mdspr3 | |
1487 | @itemx -mno-dspr3 | |
1488 | Generate code for the DSP Release 3 Application Specific Extension. | |
1489 | This option implies @samp{-mdsp} and @samp{-mdspr2}. | |
1490 | This tells the assembler to accept DSP Release 3 instructions. | |
1491 | @samp{-mno-dspr3} turns off this option. | |
1492 | ||
1493 | @item -mmsa | |
1494 | @itemx -mno-msa | |
1495 | Generate code for the MIPS SIMD Architecture Extension. | |
1496 | This tells the assembler to accept MSA instructions. | |
1497 | @samp{-mno-msa} turns off this option. | |
1498 | ||
1499 | @item -mxpa | |
1500 | @itemx -mno-xpa | |
1501 | Generate code for the MIPS eXtended Physical Address (XPA) Extension. | |
1502 | This tells the assembler to accept XPA instructions. | |
1503 | @samp{-mno-xpa} turns off this option. | |
1504 | ||
1505 | @item -mmt | |
1506 | @itemx -mno-mt | |
1507 | Generate code for the MT Application Specific Extension. | |
1508 | This tells the assembler to accept MT instructions. | |
1509 | @samp{-mno-mt} turns off this option. | |
1510 | ||
1511 | @item -mmcu | |
1512 | @itemx -mno-mcu | |
1513 | Generate code for the MCU Application Specific Extension. | |
1514 | This tells the assembler to accept MCU instructions. | |
1515 | @samp{-mno-mcu} turns off this option. | |
1516 | ||
1517 | @item -mcrc | |
1518 | @itemx -mno-crc | |
1519 | Generate code for the MIPS cyclic redundancy check (CRC) Application | |
1520 | Specific Extension. This tells the assembler to accept CRC instructions. | |
1521 | @samp{-mno-crc} turns off this option. | |
1522 | ||
1523 | @item -mginv | |
1524 | @itemx -mno-ginv | |
1525 | Generate code for the Global INValidate (GINV) Application Specific | |
1526 | Extension. This tells the assembler to accept GINV instructions. | |
1527 | @samp{-mno-ginv} turns off this option. | |
1528 | ||
1529 | @item -minsn32 | |
1530 | @itemx -mno-insn32 | |
1531 | Only use 32-bit instruction encodings when generating code for the | |
1532 | microMIPS processor. This option inhibits the use of any 16-bit | |
1533 | instructions. This is equivalent to putting @code{.set insn32} at | |
1534 | the start of the assembly file. @samp{-mno-insn32} turns off this | |
1535 | option. This is equivalent to putting @code{.set noinsn32} at the | |
1536 | start of the assembly file. By default @samp{-mno-insn32} is | |
1537 | selected, allowing all instructions to be used. | |
1538 | ||
1539 | @item --construct-floats | |
1540 | @itemx --no-construct-floats | |
1541 | The @samp{--no-construct-floats} option disables the construction of | |
1542 | double width floating point constants by loading the two halves of the | |
1543 | value into the two single width floating point registers that make up | |
1544 | the double width register. By default @samp{--construct-floats} is | |
1545 | selected, allowing construction of these floating point constants. | |
1546 | ||
1547 | @item --relax-branch | |
1548 | @itemx --no-relax-branch | |
1549 | The @samp{--relax-branch} option enables the relaxation of out-of-range | |
1550 | branches. By default @samp{--no-relax-branch} is selected, causing any | |
1551 | out-of-range branches to produce an error. | |
1552 | ||
1553 | @item -mignore-branch-isa | |
1554 | @itemx -mno-ignore-branch-isa | |
1555 | Ignore branch checks for invalid transitions between ISA modes. The | |
1556 | semantics of branches does not provide for an ISA mode switch, so in | |
1557 | most cases the ISA mode a branch has been encoded for has to be the | |
1558 | same as the ISA mode of the branch's target label. Therefore GAS has | |
1559 | checks implemented that verify in branch assembly that the two ISA | |
1560 | modes match. @samp{-mignore-branch-isa} disables these checks. By | |
1561 | default @samp{-mno-ignore-branch-isa} is selected, causing any invalid | |
1562 | branch requiring a transition between ISA modes to produce an error. | |
1563 | ||
1564 | @item -mnan=@var{encoding} | |
1565 | Select between the IEEE 754-2008 (@option{-mnan=2008}) or the legacy | |
1566 | (@option{-mnan=legacy}) NaN encoding format. The latter is the default. | |
1567 | ||
1568 | @cindex emulation | |
1569 | @item --emulation=@var{name} | |
1570 | This option was formerly used to switch between ELF and ECOFF output | |
1571 | on targets like IRIX 5 that supported both. MIPS ECOFF support was | |
1572 | removed in GAS 2.24, so the option now serves little purpose. | |
1573 | It is retained for backwards compatibility. | |
1574 | ||
1575 | The available configuration names are: @samp{mipself}, @samp{mipslelf} and | |
1576 | @samp{mipsbelf}. Choosing @samp{mipself} now has no effect, since the output | |
1577 | is always ELF. @samp{mipslelf} and @samp{mipsbelf} select little- and | |
1578 | big-endian output respectively, but @samp{-EL} and @samp{-EB} are now the | |
1579 | preferred options instead. | |
1580 | ||
1581 | @item -nocpp | |
1582 | @command{@value{AS}} ignores this option. It is accepted for compatibility with | |
1583 | the native tools. | |
1584 | ||
1585 | @item --trap | |
1586 | @itemx --no-trap | |
1587 | @itemx --break | |
1588 | @itemx --no-break | |
1589 | Control how to deal with multiplication overflow and division by zero. | |
1590 | @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception | |
1591 | (and only work for Instruction Set Architecture level 2 and higher); | |
1592 | @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a | |
1593 | break exception. | |
1594 | ||
1595 | @item -n | |
1596 | When this option is used, @command{@value{AS}} will issue a warning every | |
1597 | time it generates a nop instruction from a macro. | |
1598 | @end table | |
1599 | @c man end | |
1600 | @end ifset | |
1601 | ||
1602 | @ifset MCORE | |
1603 | The following options are available when @value{AS} is configured for | |
1604 | an MCore processor. | |
1605 | ||
1606 | @table @gcctabopt | |
1607 | @item -jsri2bsr | |
1608 | @itemx -nojsri2bsr | |
1609 | Enable or disable the JSRI to BSR transformation. By default this is enabled. | |
1610 | The command line option @samp{-nojsri2bsr} can be used to disable it. | |
1611 | ||
1612 | @item -sifilter | |
1613 | @itemx -nosifilter | |
1614 | Enable or disable the silicon filter behaviour. By default this is disabled. | |
1615 | The default can be overridden by the @samp{-sifilter} command line option. | |
1616 | ||
1617 | @item -relax | |
1618 | Alter jump instructions for long displacements. | |
1619 | ||
1620 | @item -mcpu=[210|340] | |
1621 | Select the cpu type on the target hardware. This controls which instructions | |
1622 | can be assembled. | |
1623 | ||
1624 | @item -EB | |
1625 | Assemble for a big endian target. | |
1626 | ||
1627 | @item -EL | |
1628 | Assemble for a little endian target. | |
1629 | ||
1630 | @end table | |
1631 | @end ifset | |
1632 | @c man end | |
1633 | ||
1634 | @ifset METAG | |
1635 | ||
1636 | @ifclear man | |
1637 | @xref{Meta Options}, for the options available when @value{AS} is configured | |
1638 | for a Meta processor. | |
1639 | @end ifclear | |
1640 | ||
1641 | @ifset man | |
1642 | @c man begin OPTIONS | |
1643 | The following options are available when @value{AS} is configured for a | |
1644 | Meta processor. | |
1645 | @c man end | |
1646 | @c man begin INCLUDE | |
1647 | @include c-metag.texi | |
1648 | @c ended inside the included file | |
1649 | @end ifset | |
1650 | ||
1651 | @end ifset | |
1652 | ||
1653 | @c man begin OPTIONS | |
1654 | @ifset MMIX | |
1655 | See the info pages for documentation of the MMIX-specific options. | |
1656 | @end ifset | |
1657 | ||
1658 | @ifset NDS32 | |
1659 | ||
1660 | @ifclear man | |
1661 | @xref{NDS32 Options}, for the options available when @value{AS} is configured | |
1662 | for a NDS32 processor. | |
1663 | @end ifclear | |
1664 | @c ended inside the included file | |
1665 | @end ifset | |
1666 | ||
1667 | @ifset man | |
1668 | @c man begin OPTIONS | |
1669 | The following options are available when @value{AS} is configured for a | |
1670 | NDS32 processor. | |
1671 | @c man end | |
1672 | @c man begin INCLUDE | |
1673 | @include c-nds32.texi | |
1674 | @c ended inside the included file | |
1675 | @end ifset | |
1676 | ||
1677 | @c man end | |
1678 | @ifset PPC | |
1679 | ||
1680 | @ifclear man | |
1681 | @xref{PowerPC-Opts}, for the options available when @value{AS} is configured | |
1682 | for a PowerPC processor. | |
1683 | @end ifclear | |
1684 | ||
1685 | @ifset man | |
1686 | @c man begin OPTIONS | |
1687 | The following options are available when @value{AS} is configured for a | |
1688 | PowerPC processor. | |
1689 | @c man end | |
1690 | @c man begin INCLUDE | |
1691 | @include c-ppc.texi | |
1692 | @c ended inside the included file | |
1693 | @end ifset | |
1694 | ||
1695 | @end ifset | |
1696 | ||
1697 | @ifset RISCV | |
1698 | ||
1699 | @ifclear man | |
1700 | @xref{RISC-V-Options}, for the options available when @value{AS} is configured | |
1701 | for a RISC-V processor. | |
1702 | @end ifclear | |
1703 | ||
1704 | @ifset man | |
1705 | @c man begin OPTIONS | |
1706 | The following options are available when @value{AS} is configured for a | |
1707 | RISC-V processor. | |
1708 | @c man end | |
1709 | @c man begin INCLUDE | |
1710 | @include c-riscv.texi | |
1711 | @c ended inside the included file | |
1712 | @end ifset | |
1713 | ||
1714 | @end ifset | |
1715 | ||
1716 | @c man begin OPTIONS | |
1717 | @ifset RX | |
1718 | See the info pages for documentation of the RX-specific options. | |
1719 | @end ifset | |
1720 | ||
1721 | @ifset S390 | |
1722 | The following options are available when @value{AS} is configured for the s390 | |
1723 | processor family. | |
1724 | ||
1725 | @table @gcctabopt | |
1726 | @item -m31 | |
1727 | @itemx -m64 | |
1728 | Select the word size, either 31/32 bits or 64 bits. | |
1729 | @item -mesa | |
1730 | @item -mzarch | |
1731 | Select the architecture mode, either the Enterprise System | |
1732 | Architecture (esa) or the z/Architecture mode (zarch). | |
1733 | @item -march=@var{processor} | |
1734 | Specify which s390 processor variant is the target, @samp{g5} (or | |
1735 | @samp{arch3}), @samp{g6}, @samp{z900} (or @samp{arch5}), @samp{z990} (or | |
1736 | @samp{arch6}), @samp{z9-109}, @samp{z9-ec} (or @samp{arch7}), @samp{z10} (or | |
1737 | @samp{arch8}), @samp{z196} (or @samp{arch9}), @samp{zEC12} (or @samp{arch10}), | |
1738 | @samp{z13} (or @samp{arch11}), or @samp{z14} (or @samp{arch12}). | |
1739 | @item -mregnames | |
1740 | @itemx -mno-regnames | |
1741 | Allow or disallow symbolic names for registers. | |
1742 | @item -mwarn-areg-zero | |
1743 | Warn whenever the operand for a base or index register has been specified | |
1744 | but evaluates to zero. | |
1745 | @end table | |
1746 | @end ifset | |
1747 | @c man end | |
1748 | ||
1749 | @ifset TIC6X | |
1750 | ||
1751 | @ifclear man | |
1752 | @xref{TIC6X Options}, for the options available when @value{AS} is configured | |
1753 | for a TMS320C6000 processor. | |
1754 | @end ifclear | |
1755 | ||
1756 | @ifset man | |
1757 | @c man begin OPTIONS | |
1758 | The following options are available when @value{AS} is configured for a | |
1759 | TMS320C6000 processor. | |
1760 | @c man end | |
1761 | @c man begin INCLUDE | |
1762 | @include c-tic6x.texi | |
1763 | @c ended inside the included file | |
1764 | @end ifset | |
1765 | ||
1766 | @end ifset | |
1767 | ||
1768 | @ifset TILEGX | |
1769 | ||
1770 | @ifclear man | |
1771 | @xref{TILE-Gx Options}, for the options available when @value{AS} is configured | |
1772 | for a TILE-Gx processor. | |
1773 | @end ifclear | |
1774 | ||
1775 | @ifset man | |
1776 | @c man begin OPTIONS | |
1777 | The following options are available when @value{AS} is configured for a TILE-Gx | |
1778 | processor. | |
1779 | @c man end | |
1780 | @c man begin INCLUDE | |
1781 | @include c-tilegx.texi | |
1782 | @c ended inside the included file | |
1783 | @end ifset | |
1784 | ||
1785 | @end ifset | |
1786 | ||
1787 | @ifset VISIUM | |
1788 | ||
1789 | @ifclear man | |
1790 | @xref{Visium Options}, for the options available when @value{AS} is configured | |
1791 | for a Visium processor. | |
1792 | @end ifclear | |
1793 | ||
1794 | @ifset man | |
1795 | @c man begin OPTIONS | |
1796 | The following option is available when @value{AS} is configured for a Visium | |
1797 | processor. | |
1798 | @c man end | |
1799 | @c man begin INCLUDE | |
1800 | @include c-visium.texi | |
1801 | @c ended inside the included file | |
1802 | @end ifset | |
1803 | ||
1804 | @end ifset | |
1805 | ||
1806 | @ifset XTENSA | |
1807 | ||
1808 | @ifclear man | |
1809 | @xref{Xtensa Options}, for the options available when @value{AS} is configured | |
1810 | for an Xtensa processor. | |
1811 | @end ifclear | |
1812 | ||
1813 | @ifset man | |
1814 | @c man begin OPTIONS | |
1815 | The following options are available when @value{AS} is configured for an | |
1816 | Xtensa processor. | |
1817 | @c man end | |
1818 | @c man begin INCLUDE | |
1819 | @include c-xtensa.texi | |
1820 | @c ended inside the included file | |
1821 | @end ifset | |
1822 | ||
1823 | @end ifset | |
1824 | ||
1825 | @c man begin OPTIONS | |
1826 | ||
1827 | @ifset Z80 | |
1828 | The following options are available when @value{AS} is configured for | |
1829 | a Z80 family processor. | |
1830 | @table @gcctabopt | |
1831 | @item -z80 | |
1832 | Assemble for Z80 processor. | |
1833 | @item -r800 | |
1834 | Assemble for R800 processor. | |
1835 | @item -ignore-undocumented-instructions | |
1836 | @itemx -Wnud | |
1837 | Assemble undocumented Z80 instructions that also work on R800 without warning. | |
1838 | @item -ignore-unportable-instructions | |
1839 | @itemx -Wnup | |
1840 | Assemble all undocumented Z80 instructions without warning. | |
1841 | @item -warn-undocumented-instructions | |
1842 | @itemx -Wud | |
1843 | Issue a warning for undocumented Z80 instructions that also work on R800. | |
1844 | @item -warn-unportable-instructions | |
1845 | @itemx -Wup | |
1846 | Issue a warning for undocumented Z80 instructions that do not work on R800. | |
1847 | @item -forbid-undocumented-instructions | |
1848 | @itemx -Fud | |
1849 | Treat all undocumented instructions as errors. | |
1850 | @item -forbid-unportable-instructions | |
1851 | @itemx -Fup | |
1852 | Treat undocumented Z80 instructions that do not work on R800 as errors. | |
1853 | @end table | |
1854 | @end ifset | |
1855 | ||
1856 | @c man end | |
1857 | ||
1858 | @menu | |
1859 | * Manual:: Structure of this Manual | |
1860 | * GNU Assembler:: The GNU Assembler | |
1861 | * Object Formats:: Object File Formats | |
1862 | * Command Line:: Command Line | |
1863 | * Input Files:: Input Files | |
1864 | * Object:: Output (Object) File | |
1865 | * Errors:: Error and Warning Messages | |
1866 | @end menu | |
1867 | ||
1868 | @node Manual | |
1869 | @section Structure of this Manual | |
1870 | ||
1871 | @cindex manual, structure and purpose | |
1872 | This manual is intended to describe what you need to know to use | |
1873 | @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including | |
1874 | notation for symbols, constants, and expressions; the directives that | |
1875 | @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}. | |
1876 | ||
1877 | @ifclear GENERIC | |
1878 | We also cover special features in the @value{TARGET} | |
1879 | configuration of @command{@value{AS}}, including assembler directives. | |
1880 | @end ifclear | |
1881 | @ifset GENERIC | |
1882 | This manual also describes some of the machine-dependent features of | |
1883 | various flavors of the assembler. | |
1884 | @end ifset | |
1885 | ||
1886 | @cindex machine instructions (not covered) | |
1887 | On the other hand, this manual is @emph{not} intended as an introduction | |
1888 | to programming in assembly language---let alone programming in general! | |
1889 | In a similar vein, we make no attempt to introduce the machine | |
1890 | architecture; we do @emph{not} describe the instruction set, standard | |
1891 | mnemonics, registers or addressing modes that are standard to a | |
1892 | particular architecture. | |
1893 | @ifset GENERIC | |
1894 | You may want to consult the manufacturer's | |
1895 | machine architecture manual for this information. | |
1896 | @end ifset | |
1897 | @ifclear GENERIC | |
1898 | @ifset H8/300 | |
1899 | For information on the H8/300 machine instruction set, see @cite{H8/300 | |
1900 | Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series | |
1901 | Programming Manual} (Renesas). | |
1902 | @end ifset | |
1903 | @ifset SH | |
1904 | For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set, | |
1905 | see @cite{SH-Microcomputer User's Manual} (Renesas) or | |
1906 | @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and | |
1907 | @cite{SuperH (SH) 64-Bit RISC Series} (SuperH). | |
1908 | @end ifset | |
1909 | @ifset Z8000 | |
1910 | For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual} | |
1911 | @end ifset | |
1912 | @end ifclear | |
1913 | ||
1914 | @c I think this is premature---doc@cygnus.com, 17jan1991 | |
1915 | @ignore | |
1916 | Throughout this manual, we assume that you are running @dfn{GNU}, | |
1917 | the portable operating system from the @dfn{Free Software | |
1918 | Foundation, Inc.}. This restricts our attention to certain kinds of | |
1919 | computer (in particular, the kinds of computers that @sc{gnu} can run on); | |
1920 | once this assumption is granted examples and definitions need less | |
1921 | qualification. | |
1922 | ||
1923 | @command{@value{AS}} is part of a team of programs that turn a high-level | |
1924 | human-readable series of instructions into a low-level | |
1925 | computer-readable series of instructions. Different versions of | |
1926 | @command{@value{AS}} are used for different kinds of computer. | |
1927 | @end ignore | |
1928 | ||
1929 | @c There used to be a section "Terminology" here, which defined | |
1930 | @c "contents", "byte", "word", and "long". Defining "word" to any | |
1931 | @c particular size is confusing when the .word directive may generate 16 | |
1932 | @c bits on one machine and 32 bits on another; in general, for the user | |
1933 | @c version of this manual, none of these terms seem essential to define. | |
1934 | @c They were used very little even in the former draft of the manual; | |
1935 | @c this draft makes an effort to avoid them (except in names of | |
1936 | @c directives). | |
1937 | ||
1938 | @node GNU Assembler | |
1939 | @section The GNU Assembler | |
1940 | ||
1941 | @c man begin DESCRIPTION | |
1942 | ||
1943 | @sc{gnu} @command{as} is really a family of assemblers. | |
1944 | @ifclear GENERIC | |
1945 | This manual describes @command{@value{AS}}, a member of that family which is | |
1946 | configured for the @value{TARGET} architectures. | |
1947 | @end ifclear | |
1948 | If you use (or have used) the @sc{gnu} assembler on one architecture, you | |
1949 | should find a fairly similar environment when you use it on another | |
1950 | architecture. Each version has much in common with the others, | |
1951 | including object file formats, most assembler directives (often called | |
1952 | @dfn{pseudo-ops}) and assembler syntax.@refill | |
1953 | ||
1954 | @cindex purpose of @sc{gnu} assembler | |
1955 | @command{@value{AS}} is primarily intended to assemble the output of the | |
1956 | @sc{gnu} C compiler @code{@value{GCC}} for use by the linker | |
1957 | @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}} | |
1958 | assemble correctly everything that other assemblers for the same | |
1959 | machine would assemble. | |
1960 | @ifset VAX | |
1961 | Any exceptions are documented explicitly (@pxref{Machine Dependencies}). | |
1962 | @end ifset | |
1963 | @ifset M680X0 | |
1964 | @c This remark should appear in generic version of manual; assumption | |
1965 | @c here is that generic version sets M680x0. | |
1966 | This doesn't mean @command{@value{AS}} always uses the same syntax as another | |
1967 | assembler for the same architecture; for example, we know of several | |
1968 | incompatible versions of 680x0 assembly language syntax. | |
1969 | @end ifset | |
1970 | ||
1971 | @c man end | |
1972 | ||
1973 | Unlike older assemblers, @command{@value{AS}} is designed to assemble a source | |
1974 | program in one pass of the source file. This has a subtle impact on the | |
1975 | @kbd{.org} directive (@pxref{Org,,@code{.org}}). | |
1976 | ||
1977 | @node Object Formats | |
1978 | @section Object File Formats | |
1979 | ||
1980 | @cindex object file format | |
1981 | The @sc{gnu} assembler can be configured to produce several alternative | |
1982 | object file formats. For the most part, this does not affect how you | |
1983 | write assembly language programs; but directives for debugging symbols | |
1984 | are typically different in different file formats. @xref{Symbol | |
1985 | Attributes,,Symbol Attributes}. | |
1986 | @ifclear GENERIC | |
1987 | @ifclear MULTI-OBJ | |
1988 | For the @value{TARGET} target, @command{@value{AS}} is configured to produce | |
1989 | @value{OBJ-NAME} format object files. | |
1990 | @end ifclear | |
1991 | @c The following should exhaust all configs that set MULTI-OBJ, ideally | |
1992 | @ifset HPPA | |
1993 | On the @value{TARGET}, @command{@value{AS}} can be configured to produce either | |
1994 | SOM or ELF format object files. | |
1995 | @end ifset | |
1996 | @end ifclear | |
1997 | ||
1998 | @node Command Line | |
1999 | @section Command Line | |
2000 | ||
2001 | @cindex command line conventions | |
2002 | ||
2003 | After the program name @command{@value{AS}}, the command line may contain | |
2004 | options and file names. Options may appear in any order, and may be | |
2005 | before, after, or between file names. The order of file names is | |
2006 | significant. | |
2007 | ||
2008 | @cindex standard input, as input file | |
2009 | @kindex -- | |
2010 | @file{--} (two hyphens) by itself names the standard input file | |
2011 | explicitly, as one of the files for @command{@value{AS}} to assemble. | |
2012 | ||
2013 | @cindex options, command line | |
2014 | Except for @samp{--} any command line argument that begins with a | |
2015 | hyphen (@samp{-}) is an option. Each option changes the behavior of | |
2016 | @command{@value{AS}}. No option changes the way another option works. An | |
2017 | option is a @samp{-} followed by one or more letters; the case of | |
2018 | the letter is important. All options are optional. | |
2019 | ||
2020 | Some options expect exactly one file name to follow them. The file | |
2021 | name may either immediately follow the option's letter (compatible | |
2022 | with older assemblers) or it may be the next command argument (@sc{gnu} | |
2023 | standard). These two command lines are equivalent: | |
2024 | ||
2025 | @smallexample | |
2026 | @value{AS} -o my-object-file.o mumble.s | |
2027 | @value{AS} -omy-object-file.o mumble.s | |
2028 | @end smallexample | |
2029 | ||
2030 | @node Input Files | |
2031 | @section Input Files | |
2032 | ||
2033 | @cindex input | |
2034 | @cindex source program | |
2035 | @cindex files, input | |
2036 | We use the phrase @dfn{source program}, abbreviated @dfn{source}, to | |
2037 | describe the program input to one run of @command{@value{AS}}. The program may | |
2038 | be in one or more files; how the source is partitioned into files | |
2039 | doesn't change the meaning of the source. | |
2040 | ||
2041 | @c I added "con" prefix to "catenation" just to prove I can overcome my | |
2042 | @c APL training... doc@cygnus.com | |
2043 | The source program is a concatenation of the text in all the files, in the | |
2044 | order specified. | |
2045 | ||
2046 | @c man begin DESCRIPTION | |
2047 | Each time you run @command{@value{AS}} it assembles exactly one source | |
2048 | program. The source program is made up of one or more files. | |
2049 | (The standard input is also a file.) | |
2050 | ||
2051 | You give @command{@value{AS}} a command line that has zero or more input file | |
2052 | names. The input files are read (from left file name to right). A | |
2053 | command line argument (in any position) that has no special meaning | |
2054 | is taken to be an input file name. | |
2055 | ||
2056 | If you give @command{@value{AS}} no file names it attempts to read one input file | |
2057 | from the @command{@value{AS}} standard input, which is normally your terminal. You | |
2058 | may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program | |
2059 | to assemble. | |
2060 | ||
2061 | Use @samp{--} if you need to explicitly name the standard input file | |
2062 | in your command line. | |
2063 | ||
2064 | If the source is empty, @command{@value{AS}} produces a small, empty object | |
2065 | file. | |
2066 | ||
2067 | @c man end | |
2068 | ||
2069 | @subheading Filenames and Line-numbers | |
2070 | ||
2071 | @cindex input file linenumbers | |
2072 | @cindex line numbers, in input files | |
2073 | There are two ways of locating a line in the input file (or files) and | |
2074 | either may be used in reporting error messages. One way refers to a line | |
2075 | number in a physical file; the other refers to a line number in a | |
2076 | ``logical'' file. @xref{Errors, ,Error and Warning Messages}. | |
2077 | ||
2078 | @dfn{Physical files} are those files named in the command line given | |
2079 | to @command{@value{AS}}. | |
2080 | ||
2081 | @dfn{Logical files} are simply names declared explicitly by assembler | |
2082 | directives; they bear no relation to physical files. Logical file names help | |
2083 | error messages reflect the original source file, when @command{@value{AS}} source | |
2084 | is itself synthesized from other files. @command{@value{AS}} understands the | |
2085 | @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also | |
2086 | @ref{File,,@code{.file}}. | |
2087 | ||
2088 | @node Object | |
2089 | @section Output (Object) File | |
2090 | ||
2091 | @cindex object file | |
2092 | @cindex output file | |
2093 | @kindex a.out | |
2094 | @kindex .o | |
2095 | Every time you run @command{@value{AS}} it produces an output file, which is | |
2096 | your assembly language program translated into numbers. This file | |
2097 | is the object file. Its default name is @code{a.out}. | |
2098 | You can give it another name by using the @option{-o} option. Conventionally, | |
2099 | object file names end with @file{.o}. The default name is used for historical | |
2100 | reasons: older assemblers were capable of assembling self-contained programs | |
2101 | directly into a runnable program. (For some formats, this isn't currently | |
2102 | possible, but it can be done for the @code{a.out} format.) | |
2103 | ||
2104 | @cindex linker | |
2105 | @kindex ld | |
2106 | The object file is meant for input to the linker @code{@value{LD}}. It contains | |
2107 | assembled program code, information to help @code{@value{LD}} integrate | |
2108 | the assembled program into a runnable file, and (optionally) symbolic | |
2109 | information for the debugger. | |
2110 | ||
2111 | @c link above to some info file(s) like the description of a.out. | |
2112 | @c don't forget to describe @sc{gnu} info as well as Unix lossage. | |
2113 | ||
2114 | @node Errors | |
2115 | @section Error and Warning Messages | |
2116 | ||
2117 | @c man begin DESCRIPTION | |
2118 | ||
2119 | @cindex error messages | |
2120 | @cindex warning messages | |
2121 | @cindex messages from assembler | |
2122 | @command{@value{AS}} may write warnings and error messages to the standard error | |
2123 | file (usually your terminal). This should not happen when a compiler | |
2124 | runs @command{@value{AS}} automatically. Warnings report an assumption made so | |
2125 | that @command{@value{AS}} could keep assembling a flawed program; errors report a | |
2126 | grave problem that stops the assembly. | |
2127 | ||
2128 | @c man end | |
2129 | ||
2130 | @cindex format of warning messages | |
2131 | Warning messages have the format | |
2132 | ||
2133 | @smallexample | |
2134 | file_name:@b{NNN}:Warning Message Text | |
2135 | @end smallexample | |
2136 | ||
2137 | @noindent | |
2138 | @cindex file names and line numbers, in warnings/errors | |
2139 | (where @b{NNN} is a line number). If both a logical file name | |
2140 | (@pxref{File,,@code{.file}}) and a logical line number | |
2141 | @ifset GENERIC | |
2142 | (@pxref{Line,,@code{.line}}) | |
2143 | @end ifset | |
2144 | have been given then they will be used, otherwise the file name and line number | |
2145 | in the current assembler source file will be used. The message text is | |
2146 | intended to be self explanatory (in the grand Unix tradition). | |
2147 | ||
2148 | Note the file name must be set via the logical version of the @code{.file} | |
2149 | directive, not the DWARF2 version of the @code{.file} directive. For example: | |
2150 | ||
2151 | @smallexample | |
2152 | .file 2 "bar.c" | |
2153 | error_assembler_source | |
2154 | .file "foo.c" | |
2155 | .line 30 | |
2156 | error_c_source | |
2157 | @end smallexample | |
2158 | ||
2159 | produces this output: | |
2160 | ||
2161 | @smallexample | |
2162 | Assembler messages: | |
2163 | asm.s:2: Error: no such instruction: `error_assembler_source' | |
2164 | foo.c:31: Error: no such instruction: `error_c_source' | |
2165 | @end smallexample | |
2166 | ||
2167 | @cindex format of error messages | |
2168 | Error messages have the format | |
2169 | ||
2170 | @smallexample | |
2171 | file_name:@b{NNN}:FATAL:Error Message Text | |
2172 | @end smallexample | |
2173 | ||
2174 | The file name and line number are derived as for warning | |
2175 | messages. The actual message text may be rather less explanatory | |
2176 | because many of them aren't supposed to happen. | |
2177 | ||
2178 | @node Invoking | |
2179 | @chapter Command-Line Options | |
2180 | ||
2181 | @cindex options, all versions of assembler | |
2182 | This chapter describes command-line options available in @emph{all} | |
2183 | versions of the @sc{gnu} assembler; see @ref{Machine Dependencies}, | |
2184 | for options specific | |
2185 | @ifclear GENERIC | |
2186 | to the @value{TARGET} target. | |
2187 | @end ifclear | |
2188 | @ifset GENERIC | |
2189 | to particular machine architectures. | |
2190 | @end ifset | |
2191 | ||
2192 | @c man begin DESCRIPTION | |
2193 | ||
2194 | If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler, | |
2195 | you can use the @samp{-Wa} option to pass arguments through to the assembler. | |
2196 | The assembler arguments must be separated from each other (and the @samp{-Wa}) | |
2197 | by commas. For example: | |
2198 | ||
2199 | @smallexample | |
2200 | gcc -c -g -O -Wa,-alh,-L file.c | |
2201 | @end smallexample | |
2202 | ||
2203 | @noindent | |
2204 | This passes two options to the assembler: @samp{-alh} (emit a listing to | |
2205 | standard output with high-level and assembly source) and @samp{-L} (retain | |
2206 | local symbols in the symbol table). | |
2207 | ||
2208 | Usually you do not need to use this @samp{-Wa} mechanism, since many compiler | |
2209 | command-line options are automatically passed to the assembler by the compiler. | |
2210 | (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see | |
2211 | precisely what options it passes to each compilation pass, including the | |
2212 | assembler.) | |
2213 | ||
2214 | @c man end | |
2215 | ||
2216 | @menu | |
2217 | * a:: -a[cdghlns] enable listings | |
2218 | * alternate:: --alternate enable alternate macro syntax | |
2219 | * D:: -D for compatibility | |
2220 | * f:: -f to work faster | |
2221 | * I:: -I for .include search path | |
2222 | @ifclear DIFF-TBL-KLUGE | |
2223 | * K:: -K for compatibility | |
2224 | @end ifclear | |
2225 | @ifset DIFF-TBL-KLUGE | |
2226 | * K:: -K for difference tables | |
2227 | @end ifset | |
2228 | ||
2229 | * L:: -L to retain local symbols | |
2230 | * listing:: --listing-XXX to configure listing output | |
2231 | * M:: -M or --mri to assemble in MRI compatibility mode | |
2232 | * MD:: --MD for dependency tracking | |
2233 | * no-pad-sections:: --no-pad-sections to stop section padding | |
2234 | * o:: -o to name the object file | |
2235 | * R:: -R to join data and text sections | |
2236 | * statistics:: --statistics to see statistics about assembly | |
2237 | * traditional-format:: --traditional-format for compatible output | |
2238 | * v:: -v to announce version | |
2239 | * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings | |
2240 | * Z:: -Z to make object file even after errors | |
2241 | @end menu | |
2242 | ||
2243 | @node a | |
2244 | @section Enable Listings: @option{-a[cdghlns]} | |
2245 | ||
2246 | @kindex -a | |
2247 | @kindex -ac | |
2248 | @kindex -ad | |
2249 | @kindex -ag | |
2250 | @kindex -ah | |
2251 | @kindex -al | |
2252 | @kindex -an | |
2253 | @kindex -as | |
2254 | @cindex listings, enabling | |
2255 | @cindex assembly listings, enabling | |
2256 | ||
2257 | These options enable listing output from the assembler. By itself, | |
2258 | @samp{-a} requests high-level, assembly, and symbols listing. | |
2259 | You can use other letters to select specific options for the list: | |
2260 | @samp{-ah} requests a high-level language listing, | |
2261 | @samp{-al} requests an output-program assembly listing, and | |
2262 | @samp{-as} requests a symbol table listing. | |
2263 | High-level listings require that a compiler debugging option like | |
2264 | @samp{-g} be used, and that assembly listings (@samp{-al}) be requested | |
2265 | also. | |
2266 | ||
2267 | Use the @samp{-ag} option to print a first section with general assembly | |
2268 | information, like @value{AS} version, switches passed, or time stamp. | |
2269 | ||
2270 | Use the @samp{-ac} option to omit false conditionals from a listing. Any lines | |
2271 | which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any | |
2272 | other conditional), or a true @code{.if} followed by an @code{.else}, will be | |
2273 | omitted from the listing. | |
2274 | ||
2275 | Use the @samp{-ad} option to omit debugging directives from the | |
2276 | listing. | |
2277 | ||
2278 | Once you have specified one of these options, you can further control | |
2279 | listing output and its appearance using the directives @code{.list}, | |
2280 | @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and | |
2281 | @code{.sbttl}. | |
2282 | The @samp{-an} option turns off all forms processing. | |
2283 | If you do not request listing output with one of the @samp{-a} options, the | |
2284 | listing-control directives have no effect. | |
2285 | ||
2286 | The letters after @samp{-a} may be combined into one option, | |
2287 | @emph{e.g.}, @samp{-aln}. | |
2288 | ||
2289 | Note if the assembler source is coming from the standard input (e.g., | |
2290 | because it | |
2291 | is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch | |
2292 | is being used) then the listing will not contain any comments or preprocessor | |
2293 | directives. This is because the listing code buffers input source lines from | |
2294 | stdin only after they have been preprocessed by the assembler. This reduces | |
2295 | memory usage and makes the code more efficient. | |
2296 | ||
2297 | @node alternate | |
2298 | @section @option{--alternate} | |
2299 | ||
2300 | @kindex --alternate | |
2301 | Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}. | |
2302 | ||
2303 | @node D | |
2304 | @section @option{-D} | |
2305 | ||
2306 | @kindex -D | |
2307 | This option has no effect whatsoever, but it is accepted to make it more | |
2308 | likely that scripts written for other assemblers also work with | |
2309 | @command{@value{AS}}. | |
2310 | ||
2311 | @node f | |
2312 | @section Work Faster: @option{-f} | |
2313 | ||
2314 | @kindex -f | |
2315 | @cindex trusted compiler | |
2316 | @cindex faster processing (@option{-f}) | |
2317 | @samp{-f} should only be used when assembling programs written by a | |
2318 | (trusted) compiler. @samp{-f} stops the assembler from doing whitespace | |
2319 | and comment preprocessing on | |
2320 | the input file(s) before assembling them. @xref{Preprocessing, | |
2321 | ,Preprocessing}. | |
2322 | ||
2323 | @quotation | |
2324 | @emph{Warning:} if you use @samp{-f} when the files actually need to be | |
2325 | preprocessed (if they contain comments, for example), @command{@value{AS}} does | |
2326 | not work correctly. | |
2327 | @end quotation | |
2328 | ||
2329 | @node I | |
2330 | @section @code{.include} Search Path: @option{-I} @var{path} | |
2331 | ||
2332 | @kindex -I @var{path} | |
2333 | @cindex paths for @code{.include} | |
2334 | @cindex search path for @code{.include} | |
2335 | @cindex @code{include} directive search path | |
2336 | Use this option to add a @var{path} to the list of directories | |
2337 | @command{@value{AS}} searches for files specified in @code{.include} | |
2338 | directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as | |
2339 | many times as necessary to include a variety of paths. The current | |
2340 | working directory is always searched first; after that, @command{@value{AS}} | |
2341 | searches any @samp{-I} directories in the same order as they were | |
2342 | specified (left to right) on the command line. | |
2343 | ||
2344 | @node K | |
2345 | @section Difference Tables: @option{-K} | |
2346 | ||
2347 | @kindex -K | |
2348 | @ifclear DIFF-TBL-KLUGE | |
2349 | On the @value{TARGET} family, this option is allowed, but has no effect. It is | |
2350 | permitted for compatibility with the @sc{gnu} assembler on other platforms, | |
2351 | where it can be used to warn when the assembler alters the machine code | |
2352 | generated for @samp{.word} directives in difference tables. The @value{TARGET} | |
2353 | family does not have the addressing limitations that sometimes lead to this | |
2354 | alteration on other platforms. | |
2355 | @end ifclear | |
2356 | ||
2357 | @ifset DIFF-TBL-KLUGE | |
2358 | @cindex difference tables, warning | |
2359 | @cindex warning for altered difference tables | |
2360 | @command{@value{AS}} sometimes alters the code emitted for directives of the | |
2361 | form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}. | |
2362 | You can use the @samp{-K} option if you want a warning issued when this | |
2363 | is done. | |
2364 | @end ifset | |
2365 | ||
2366 | @node L | |
2367 | @section Include Local Symbols: @option{-L} | |
2368 | ||
2369 | @kindex -L | |
2370 | @cindex local symbols, retaining in output | |
2371 | Symbols beginning with system-specific local label prefixes, typically | |
2372 | @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are | |
2373 | called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see | |
2374 | such symbols when debugging, because they are intended for the use of | |
2375 | programs (like compilers) that compose assembler programs, not for your | |
2376 | notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard | |
2377 | such symbols, so you do not normally debug with them. | |
2378 | ||
2379 | This option tells @command{@value{AS}} to retain those local symbols | |
2380 | in the object file. Usually if you do this you also tell the linker | |
2381 | @code{@value{LD}} to preserve those symbols. | |
2382 | ||
2383 | @node listing | |
2384 | @section Configuring listing output: @option{--listing} | |
2385 | ||
2386 | The listing feature of the assembler can be enabled via the command line switch | |
2387 | @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a | |
2388 | hex dump of the corresponding locations in the output object file, and displays | |
2389 | them as a listing file. The format of this listing can be controlled by | |
2390 | directives inside the assembler source (i.e., @code{.list} (@pxref{List}), | |
2391 | @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}), | |
2392 | @code{.psize} (@pxref{Psize}), and | |
2393 | @code{.eject} (@pxref{Eject}) and also by the following switches: | |
2394 | ||
2395 | @table @gcctabopt | |
2396 | @item --listing-lhs-width=@samp{number} | |
2397 | @kindex --listing-lhs-width | |
2398 | @cindex Width of first line disassembly output | |
2399 | Sets the maximum width, in words, of the first line of the hex byte dump. This | |
2400 | dump appears on the left hand side of the listing output. | |
2401 | ||
2402 | @item --listing-lhs-width2=@samp{number} | |
2403 | @kindex --listing-lhs-width2 | |
2404 | @cindex Width of continuation lines of disassembly output | |
2405 | Sets the maximum width, in words, of any further lines of the hex byte dump for | |
2406 | a given input source line. If this value is not specified, it defaults to being | |
2407 | the same as the value specified for @samp{--listing-lhs-width}. If neither | |
2408 | switch is used the default is to one. | |
2409 | ||
2410 | @item --listing-rhs-width=@samp{number} | |
2411 | @kindex --listing-rhs-width | |
2412 | @cindex Width of source line output | |
2413 | Sets the maximum width, in characters, of the source line that is displayed | |
2414 | alongside the hex dump. The default value for this parameter is 100. The | |
2415 | source line is displayed on the right hand side of the listing output. | |
2416 | ||
2417 | @item --listing-cont-lines=@samp{number} | |
2418 | @kindex --listing-cont-lines | |
2419 | @cindex Maximum number of continuation lines | |
2420 | Sets the maximum number of continuation lines of hex dump that will be | |
2421 | displayed for a given single line of source input. The default value is 4. | |
2422 | @end table | |
2423 | ||
2424 | @node M | |
2425 | @section Assemble in MRI Compatibility Mode: @option{-M} | |
2426 | ||
2427 | @kindex -M | |
2428 | @cindex MRI compatibility mode | |
2429 | The @option{-M} or @option{--mri} option selects MRI compatibility mode. This | |
2430 | changes the syntax and pseudo-op handling of @command{@value{AS}} to make it | |
2431 | compatible with the @code{ASM68K} assembler from Microtec Research. | |
2432 | The exact nature of the | |
2433 | MRI syntax will not be documented here; see the MRI manuals for more | |
2434 | information. Note in particular that the handling of macros and macro | |
2435 | arguments is somewhat different. The purpose of this option is to permit | |
2436 | assembling existing MRI assembler code using @command{@value{AS}}. | |
2437 | ||
2438 | The MRI compatibility is not complete. Certain operations of the MRI assembler | |
2439 | depend upon its object file format, and can not be supported using other object | |
2440 | file formats. Supporting these would require enhancing each object file format | |
2441 | individually. These are: | |
2442 | ||
2443 | @itemize @bullet | |
2444 | @item global symbols in common section | |
2445 | ||
2446 | The m68k MRI assembler supports common sections which are merged by the linker. | |
2447 | Other object file formats do not support this. @command{@value{AS}} handles | |
2448 | common sections by treating them as a single common symbol. It permits local | |
2449 | symbols to be defined within a common section, but it can not support global | |
2450 | symbols, since it has no way to describe them. | |
2451 | ||
2452 | @item complex relocations | |
2453 | ||
2454 | The MRI assemblers support relocations against a negated section address, and | |
2455 | relocations which combine the start addresses of two or more sections. These | |
2456 | are not support by other object file formats. | |
2457 | ||
2458 | @item @code{END} pseudo-op specifying start address | |
2459 | ||
2460 | The MRI @code{END} pseudo-op permits the specification of a start address. | |
2461 | This is not supported by other object file formats. The start address may | |
2462 | instead be specified using the @option{-e} option to the linker, or in a linker | |
2463 | script. | |
2464 | ||
2465 | @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops | |
2466 | ||
2467 | The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module | |
2468 | name to the output file. This is not supported by other object file formats. | |
2469 | ||
2470 | @item @code{ORG} pseudo-op | |
2471 | ||
2472 | The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given | |
2473 | address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op, | |
2474 | which changes the location within the current section. Absolute sections are | |
2475 | not supported by other object file formats. The address of a section may be | |
2476 | assigned within a linker script. | |
2477 | @end itemize | |
2478 | ||
2479 | There are some other features of the MRI assembler which are not supported by | |
2480 | @command{@value{AS}}, typically either because they are difficult or because they | |
2481 | seem of little consequence. Some of these may be supported in future releases. | |
2482 | ||
2483 | @itemize @bullet | |
2484 | ||
2485 | @item EBCDIC strings | |
2486 | ||
2487 | EBCDIC strings are not supported. | |
2488 | ||
2489 | @item packed binary coded decimal | |
2490 | ||
2491 | Packed binary coded decimal is not supported. This means that the @code{DC.P} | |
2492 | and @code{DCB.P} pseudo-ops are not supported. | |
2493 | ||
2494 | @item @code{FEQU} pseudo-op | |
2495 | ||
2496 | The m68k @code{FEQU} pseudo-op is not supported. | |
2497 | ||
2498 | @item @code{NOOBJ} pseudo-op | |
2499 | ||
2500 | The m68k @code{NOOBJ} pseudo-op is not supported. | |
2501 | ||
2502 | @item @code{OPT} branch control options | |
2503 | ||
2504 | The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB}, | |
2505 | @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically | |
2506 | relaxes all branches, whether forward or backward, to an appropriate size, so | |
2507 | these options serve no purpose. | |
2508 | ||
2509 | @item @code{OPT} list control options | |
2510 | ||
2511 | The following m68k @code{OPT} list control options are ignored: @code{C}, | |
2512 | @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M}, | |
2513 | @code{MEX}, @code{MC}, @code{MD}, @code{X}. | |
2514 | ||
2515 | @item other @code{OPT} options | |
2516 | ||
2517 | The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O}, | |
2518 | @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}. | |
2519 | ||
2520 | @item @code{OPT} @code{D} option is default | |
2521 | ||
2522 | The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler. | |
2523 | @code{OPT NOD} may be used to turn it off. | |
2524 | ||
2525 | @item @code{XREF} pseudo-op. | |
2526 | ||
2527 | The m68k @code{XREF} pseudo-op is ignored. | |
2528 | ||
2529 | @end itemize | |
2530 | ||
2531 | @node MD | |
2532 | @section Dependency Tracking: @option{--MD} | |
2533 | ||
2534 | @kindex --MD | |
2535 | @cindex dependency tracking | |
2536 | @cindex make rules | |
2537 | ||
2538 | @command{@value{AS}} can generate a dependency file for the file it creates. This | |
2539 | file consists of a single rule suitable for @code{make} describing the | |
2540 | dependencies of the main source file. | |
2541 | ||
2542 | The rule is written to the file named in its argument. | |
2543 | ||
2544 | This feature is used in the automatic updating of makefiles. | |
2545 | ||
2546 | @node no-pad-sections | |
2547 | @section Output Section Padding | |
2548 | @kindex --no-pad-sections | |
2549 | @cindex output section padding | |
2550 | Normally the assembler will pad the end of each output section up to its | |
2551 | alignment boundary. But this can waste space, which can be significant on | |
2552 | memory constrained targets. So the @option{--no-pad-sections} option will | |
2553 | disable this behaviour. | |
2554 | ||
2555 | @node o | |
2556 | @section Name the Object File: @option{-o} | |
2557 | ||
2558 | @kindex -o | |
2559 | @cindex naming object file | |
2560 | @cindex object file name | |
2561 | There is always one object file output when you run @command{@value{AS}}. By | |
2562 | default it has the name @file{a.out}. | |
2563 | You use this option (which takes exactly one filename) to give the | |
2564 | object file a different name. | |
2565 | ||
2566 | Whatever the object file is called, @command{@value{AS}} overwrites any | |
2567 | existing file of the same name. | |
2568 | ||
2569 | @node R | |
2570 | @section Join Data and Text Sections: @option{-R} | |
2571 | ||
2572 | @kindex -R | |
2573 | @cindex data and text sections, joining | |
2574 | @cindex text and data sections, joining | |
2575 | @cindex joining text and data sections | |
2576 | @cindex merging text and data sections | |
2577 | @option{-R} tells @command{@value{AS}} to write the object file as if all | |
2578 | data-section data lives in the text section. This is only done at | |
2579 | the very last moment: your binary data are the same, but data | |
2580 | section parts are relocated differently. The data section part of | |
2581 | your object file is zero bytes long because all its bytes are | |
2582 | appended to the text section. (@xref{Sections,,Sections and Relocation}.) | |
2583 | ||
2584 | When you specify @option{-R} it would be possible to generate shorter | |
2585 | address displacements (because we do not have to cross between text and | |
2586 | data section). We refrain from doing this simply for compatibility with | |
2587 | older versions of @command{@value{AS}}. In future, @option{-R} may work this way. | |
2588 | ||
2589 | @ifset COFF-ELF | |
2590 | When @command{@value{AS}} is configured for COFF or ELF output, | |
2591 | this option is only useful if you use sections named @samp{.text} and | |
2592 | @samp{.data}. | |
2593 | @end ifset | |
2594 | ||
2595 | @ifset HPPA | |
2596 | @option{-R} is not supported for any of the HPPA targets. Using | |
2597 | @option{-R} generates a warning from @command{@value{AS}}. | |
2598 | @end ifset | |
2599 | ||
2600 | @node statistics | |
2601 | @section Display Assembly Statistics: @option{--statistics} | |
2602 | ||
2603 | @kindex --statistics | |
2604 | @cindex statistics, about assembly | |
2605 | @cindex time, total for assembly | |
2606 | @cindex space used, maximum for assembly | |
2607 | Use @samp{--statistics} to display two statistics about the resources used by | |
2608 | @command{@value{AS}}: the maximum amount of space allocated during the assembly | |
2609 | (in bytes), and the total execution time taken for the assembly (in @sc{cpu} | |
2610 | seconds). | |
2611 | ||
2612 | @node traditional-format | |
2613 | @section Compatible Output: @option{--traditional-format} | |
2614 | ||
2615 | @kindex --traditional-format | |
2616 | For some targets, the output of @command{@value{AS}} is different in some ways | |
2617 | from the output of some existing assembler. This switch requests | |
2618 | @command{@value{AS}} to use the traditional format instead. | |
2619 | ||
2620 | For example, it disables the exception frame optimizations which | |
2621 | @command{@value{AS}} normally does by default on @code{@value{GCC}} output. | |
2622 | ||
2623 | @node v | |
2624 | @section Announce Version: @option{-v} | |
2625 | ||
2626 | @kindex -v | |
2627 | @kindex -version | |
2628 | @cindex assembler version | |
2629 | @cindex version of assembler | |
2630 | You can find out what version of as is running by including the | |
2631 | option @samp{-v} (which you can also spell as @samp{-version}) on the | |
2632 | command line. | |
2633 | ||
2634 | @node W | |
2635 | @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings} | |
2636 | ||
2637 | @command{@value{AS}} should never give a warning or error message when | |
2638 | assembling compiler output. But programs written by people often | |
2639 | cause @command{@value{AS}} to give a warning that a particular assumption was | |
2640 | made. All such warnings are directed to the standard error file. | |
2641 | ||
2642 | @kindex -W | |
2643 | @kindex --no-warn | |
2644 | @cindex suppressing warnings | |
2645 | @cindex warnings, suppressing | |
2646 | If you use the @option{-W} and @option{--no-warn} options, no warnings are issued. | |
2647 | This only affects the warning messages: it does not change any particular of | |
2648 | how @command{@value{AS}} assembles your file. Errors, which stop the assembly, | |
2649 | are still reported. | |
2650 | ||
2651 | @kindex --fatal-warnings | |
2652 | @cindex errors, caused by warnings | |
2653 | @cindex warnings, causing error | |
2654 | If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers | |
2655 | files that generate warnings to be in error. | |
2656 | ||
2657 | @kindex --warn | |
2658 | @cindex warnings, switching on | |
2659 | You can switch these options off again by specifying @option{--warn}, which | |
2660 | causes warnings to be output as usual. | |
2661 | ||
2662 | @node Z | |
2663 | @section Generate Object File in Spite of Errors: @option{-Z} | |
2664 | @cindex object file, after errors | |
2665 | @cindex errors, continuing after | |
2666 | After an error message, @command{@value{AS}} normally produces no output. If for | |
2667 | some reason you are interested in object file output even after | |
2668 | @command{@value{AS}} gives an error message on your program, use the @samp{-Z} | |
2669 | option. If there are any errors, @command{@value{AS}} continues anyways, and | |
2670 | writes an object file after a final warning message of the form @samp{@var{n} | |
2671 | errors, @var{m} warnings, generating bad object file.} | |
2672 | ||
2673 | @node Syntax | |
2674 | @chapter Syntax | |
2675 | ||
2676 | @cindex machine-independent syntax | |
2677 | @cindex syntax, machine-independent | |
2678 | This chapter describes the machine-independent syntax allowed in a | |
2679 | source file. @command{@value{AS}} syntax is similar to what many other | |
2680 | assemblers use; it is inspired by the BSD 4.2 | |
2681 | @ifclear VAX | |
2682 | assembler. | |
2683 | @end ifclear | |
2684 | @ifset VAX | |
2685 | assembler, except that @command{@value{AS}} does not assemble Vax bit-fields. | |
2686 | @end ifset | |
2687 | ||
2688 | @menu | |
2689 | * Preprocessing:: Preprocessing | |
2690 | * Whitespace:: Whitespace | |
2691 | * Comments:: Comments | |
2692 | * Symbol Intro:: Symbols | |
2693 | * Statements:: Statements | |
2694 | * Constants:: Constants | |
2695 | @end menu | |
2696 | ||
2697 | @node Preprocessing | |
2698 | @section Preprocessing | |
2699 | ||
2700 | @cindex preprocessing | |
2701 | The @command{@value{AS}} internal preprocessor: | |
2702 | @itemize @bullet | |
2703 | @cindex whitespace, removed by preprocessor | |
2704 | @item | |
2705 | adjusts and removes extra whitespace. It leaves one space or tab before | |
2706 | the keywords on a line, and turns any other whitespace on the line into | |
2707 | a single space. | |
2708 | ||
2709 | @cindex comments, removed by preprocessor | |
2710 | @item | |
2711 | removes all comments, replacing them with a single space, or an | |
2712 | appropriate number of newlines. | |
2713 | ||
2714 | @cindex constants, converted by preprocessor | |
2715 | @item | |
2716 | converts character constants into the appropriate numeric values. | |
2717 | @end itemize | |
2718 | ||
2719 | It does not do macro processing, include file handling, or | |
2720 | anything else you may get from your C compiler's preprocessor. You can | |
2721 | do include file processing with the @code{.include} directive | |
2722 | (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver | |
2723 | to get other ``CPP'' style preprocessing by giving the input file a | |
2724 | @samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of | |
2725 | Output, gcc info, Using GNU CC}. | |
2726 | ||
2727 | Excess whitespace, comments, and character constants | |
2728 | cannot be used in the portions of the input text that are not | |
2729 | preprocessed. | |
2730 | ||
2731 | @cindex turning preprocessing on and off | |
2732 | @cindex preprocessing, turning on and off | |
2733 | @kindex #NO_APP | |
2734 | @kindex #APP | |
2735 | If the first line of an input file is @code{#NO_APP} or if you use the | |
2736 | @samp{-f} option, whitespace and comments are not removed from the input file. | |
2737 | Within an input file, you can ask for whitespace and comment removal in | |
2738 | specific portions of the by putting a line that says @code{#APP} before the | |
2739 | text that may contain whitespace or comments, and putting a line that says | |
2740 | @code{#NO_APP} after this text. This feature is mainly intend to support | |
2741 | @code{asm} statements in compilers whose output is otherwise free of comments | |
2742 | and whitespace. | |
2743 | ||
2744 | @node Whitespace | |
2745 | @section Whitespace | |
2746 | ||
2747 | @cindex whitespace | |
2748 | @dfn{Whitespace} is one or more blanks or tabs, in any order. | |
2749 | Whitespace is used to separate symbols, and to make programs neater for | |
2750 | people to read. Unless within character constants | |
2751 | (@pxref{Characters,,Character Constants}), any whitespace means the same | |
2752 | as exactly one space. | |
2753 | ||
2754 | @node Comments | |
2755 | @section Comments | |
2756 | ||
2757 | @cindex comments | |
2758 | There are two ways of rendering comments to @command{@value{AS}}. In both | |
2759 | cases the comment is equivalent to one space. | |
2760 | ||
2761 | Anything from @samp{/*} through the next @samp{*/} is a comment. | |
2762 | This means you may not nest these comments. | |
2763 | ||
2764 | @smallexample | |
2765 | /* | |
2766 | The only way to include a newline ('\n') in a comment | |
2767 | is to use this sort of comment. | |
2768 | */ | |
2769 | ||
2770 | /* This sort of comment does not nest. */ | |
2771 | @end smallexample | |
2772 | ||
2773 | @cindex line comment character | |
2774 | Anything from a @dfn{line comment} character up to the next newline is | |
2775 | considered a comment and is ignored. The line comment character is target | |
2776 | specific, and some targets multiple comment characters. Some targets also have | |
2777 | line comment characters that only work if they are the first character on a | |
2778 | line. Some targets use a sequence of two characters to introduce a line | |
2779 | comment. Some targets can also change their line comment characters depending | |
2780 | upon command line options that have been used. For more details see the | |
2781 | @emph{Syntax} section in the documentation for individual targets. | |
2782 | ||
2783 | If the line comment character is the hash sign (@samp{#}) then it still has the | |
2784 | special ability to enable and disable preprocessing (@pxref{Preprocessing}) and | |
2785 | to specify logical line numbers: | |
2786 | ||
2787 | @kindex # | |
2788 | @cindex lines starting with @code{#} | |
2789 | @cindex logical line numbers | |
2790 | To be compatible with past assemblers, lines that begin with @samp{#} have a | |
2791 | special interpretation. Following the @samp{#} should be an absolute | |
2792 | expression (@pxref{Expressions}): the logical line number of the @emph{next} | |
2793 | line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a | |
2794 | new logical file name. The rest of the line, if any, should be whitespace. | |
2795 | ||
2796 | If the first non-whitespace characters on the line are not numeric, | |
2797 | the line is ignored. (Just like a comment.) | |
2798 | ||
2799 | @smallexample | |
2800 | # This is an ordinary comment. | |
2801 | # 42-6 "new_file_name" # New logical file name | |
2802 | # This is logical line # 36. | |
2803 | @end smallexample | |
2804 | This feature is deprecated, and may disappear from future versions | |
2805 | of @command{@value{AS}}. | |
2806 | ||
2807 | @node Symbol Intro | |
2808 | @section Symbols | |
2809 | ||
2810 | @cindex characters used in symbols | |
2811 | @ifclear SPECIAL-SYMS | |
2812 | A @dfn{symbol} is one or more characters chosen from the set of all | |
2813 | letters (both upper and lower case), digits and the three characters | |
2814 | @samp{_.$}. | |
2815 | @end ifclear | |
2816 | @ifset SPECIAL-SYMS | |
2817 | @ifclear GENERIC | |
2818 | @ifset H8 | |
2819 | A @dfn{symbol} is one or more characters chosen from the set of all | |
2820 | letters (both upper and lower case), digits and the three characters | |
2821 | @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in | |
2822 | symbol names.) | |
2823 | @end ifset | |
2824 | @end ifclear | |
2825 | @end ifset | |
2826 | @ifset GENERIC | |
2827 | On most machines, you can also use @code{$} in symbol names; exceptions | |
2828 | are noted in @ref{Machine Dependencies}. | |
2829 | @end ifset | |
2830 | No symbol may begin with a digit. Case is significant. | |
2831 | There is no length limit; all characters are significant. Multibyte characters | |
2832 | are supported. Symbols are delimited by characters not in that set, or by the | |
2833 | beginning of a file (since the source program must end with a newline, the end | |
2834 | of a file is not a possible symbol delimiter). @xref{Symbols}. | |
2835 | ||
2836 | Symbol names may also be enclosed in double quote @code{"} characters. In such | |
2837 | cases any characters are allowed, except for the NUL character. If a double | |
2838 | quote character is to be included in the symbol name it must be preceeded by a | |
2839 | backslash @code{\} character. | |
2840 | @cindex length of symbols | |
2841 | ||
2842 | @node Statements | |
2843 | @section Statements | |
2844 | ||
2845 | @cindex statements, structure of | |
2846 | @cindex line separator character | |
2847 | @cindex statement separator character | |
2848 | ||
2849 | A @dfn{statement} ends at a newline character (@samp{\n}) or a | |
2850 | @dfn{line separator character}. The line separator character is target | |
2851 | specific and described in the @emph{Syntax} section of each | |
2852 | target's documentation. Not all targets support a line separator character. | |
2853 | The newline or line separator character is considered to be part of the | |
2854 | preceding statement. Newlines and separators within character constants are an | |
2855 | exception: they do not end statements. | |
2856 | ||
2857 | @cindex newline, required at file end | |
2858 | @cindex EOF, newline must precede | |
2859 | It is an error to end any statement with end-of-file: the last | |
2860 | character of any input file should be a newline.@refill | |
2861 | ||
2862 | An empty statement is allowed, and may include whitespace. It is ignored. | |
2863 | ||
2864 | @cindex instructions and directives | |
2865 | @cindex directives and instructions | |
2866 | @c "key symbol" is not used elsewhere in the document; seems pedantic to | |
2867 | @c @defn{} it in that case, as was done previously... doc@cygnus.com, | |
2868 | @c 13feb91. | |
2869 | A statement begins with zero or more labels, optionally followed by a | |
2870 | key symbol which determines what kind of statement it is. The key | |
2871 | symbol determines the syntax of the rest of the statement. If the | |
2872 | symbol begins with a dot @samp{.} then the statement is an assembler | |
2873 | directive: typically valid for any computer. If the symbol begins with | |
2874 | a letter the statement is an assembly language @dfn{instruction}: it | |
2875 | assembles into a machine language instruction. | |
2876 | @ifset GENERIC | |
2877 | Different versions of @command{@value{AS}} for different computers | |
2878 | recognize different instructions. In fact, the same symbol may | |
2879 | represent a different instruction in a different computer's assembly | |
2880 | language.@refill | |
2881 | @end ifset | |
2882 | ||
2883 | @cindex @code{:} (label) | |
2884 | @cindex label (@code{:}) | |
2885 | A label is a symbol immediately followed by a colon (@code{:}). | |
2886 | Whitespace before a label or after a colon is permitted, but you may not | |
2887 | have whitespace between a label's symbol and its colon. @xref{Labels}. | |
2888 | ||
2889 | @ifset HPPA | |
2890 | For HPPA targets, labels need not be immediately followed by a colon, but | |
2891 | the definition of a label must begin in column zero. This also implies that | |
2892 | only one label may be defined on each line. | |
2893 | @end ifset | |
2894 | ||
2895 | @smallexample | |
2896 | label: .directive followed by something | |
2897 | another_label: # This is an empty statement. | |
2898 | instruction operand_1, operand_2, @dots{} | |
2899 | @end smallexample | |
2900 | ||
2901 | @node Constants | |
2902 | @section Constants | |
2903 | ||
2904 | @cindex constants | |
2905 | A constant is a number, written so that its value is known by | |
2906 | inspection, without knowing any context. Like this: | |
2907 | @smallexample | |
2908 | @group | |
2909 | .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value. | |
2910 | .ascii "Ring the bell\7" # A string constant. | |
2911 | .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum. | |
2912 | .float 0f-314159265358979323846264338327\ | |
2913 | 95028841971.693993751E-40 # - pi, a flonum. | |
2914 | @end group | |
2915 | @end smallexample | |
2916 | ||
2917 | @menu | |
2918 | * Characters:: Character Constants | |
2919 | * Numbers:: Number Constants | |
2920 | @end menu | |
2921 | ||
2922 | @node Characters | |
2923 | @subsection Character Constants | |
2924 | ||
2925 | @cindex character constants | |
2926 | @cindex constants, character | |
2927 | There are two kinds of character constants. A @dfn{character} stands | |
2928 | for one character in one byte and its value may be used in | |
2929 | numeric expressions. String constants (properly called string | |
2930 | @emph{literals}) are potentially many bytes and their values may not be | |
2931 | used in arithmetic expressions. | |
2932 | ||
2933 | @menu | |
2934 | * Strings:: Strings | |
2935 | * Chars:: Characters | |
2936 | @end menu | |
2937 | ||
2938 | @node Strings | |
2939 | @subsubsection Strings | |
2940 | ||
2941 | @cindex string constants | |
2942 | @cindex constants, string | |
2943 | A @dfn{string} is written between double-quotes. It may contain | |
2944 | double-quotes or null characters. The way to get special characters | |
2945 | into a string is to @dfn{escape} these characters: precede them with | |
2946 | a backslash @samp{\} character. For example @samp{\\} represents | |
2947 | one backslash: the first @code{\} is an escape which tells | |
2948 | @command{@value{AS}} to interpret the second character literally as a backslash | |
2949 | (which prevents @command{@value{AS}} from recognizing the second @code{\} as an | |
2950 | escape character). The complete list of escapes follows. | |
2951 | ||
2952 | @cindex escape codes, character | |
2953 | @cindex character escape codes | |
2954 | @c NOTE: Cindex entries must not start with a backlash character. | |
2955 | @c NOTE: This confuses the pdf2texi script when it is creating the | |
2956 | @c NOTE: index based upon the first character and so it generates: | |
2957 | @c NOTE: \initial {\\} | |
2958 | @c NOTE: which then results in the error message: | |
2959 | @c NOTE: Argument of \\ has an extra }. | |
2960 | @c NOTE: So in the index entries below a space character has been | |
2961 | @c NOTE: prepended to avoid this problem. | |
2962 | @table @kbd | |
2963 | @c @item \a | |
2964 | @c Mnemonic for ACKnowledge; for ASCII this is octal code 007. | |
2965 | @c | |
2966 | @cindex @code{ \b} (backspace character) | |
2967 | @cindex backspace (@code{\b}) | |
2968 | @item \b | |
2969 | Mnemonic for backspace; for ASCII this is octal code 010. | |
2970 | ||
2971 | @c @item \e | |
2972 | @c Mnemonic for EOText; for ASCII this is octal code 004. | |
2973 | @c | |
2974 | @cindex @code{ \f} (formfeed character) | |
2975 | @cindex formfeed (@code{\f}) | |
2976 | @item backslash-f | |
2977 | Mnemonic for FormFeed; for ASCII this is octal code 014. | |
2978 | ||
2979 | @cindex @code{ \n} (newline character) | |
2980 | @cindex newline (@code{\n}) | |
2981 | @item \n | |
2982 | Mnemonic for newline; for ASCII this is octal code 012. | |
2983 | ||
2984 | @c @item \p | |
2985 | @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}. | |
2986 | @c | |
2987 | @cindex @code{ \r} (carriage return character) | |
2988 | @cindex carriage return (@code{backslash-r}) | |
2989 | @item \r | |
2990 | Mnemonic for carriage-Return; for ASCII this is octal code 015. | |
2991 | ||
2992 | @c @item \s | |
2993 | @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with | |
2994 | @c other assemblers. | |
2995 | @c | |
2996 | @cindex @code{ \t} (tab) | |
2997 | @cindex tab (@code{\t}) | |
2998 | @item \t | |
2999 | Mnemonic for horizontal Tab; for ASCII this is octal code 011. | |
3000 | ||
3001 | @c @item \v | |
3002 | @c Mnemonic for Vertical tab; for ASCII this is octal code 013. | |
3003 | @c @item \x @var{digit} @var{digit} @var{digit} | |
3004 | @c A hexadecimal character code. The numeric code is 3 hexadecimal digits. | |
3005 | @c | |
3006 | @cindex @code{ \@var{ddd}} (octal character code) | |
3007 | @cindex octal character code (@code{\@var{ddd}}) | |
3008 | @item \ @var{digit} @var{digit} @var{digit} | |
3009 | An octal character code. The numeric code is 3 octal digits. | |
3010 | For compatibility with other Unix systems, 8 and 9 are accepted as digits: | |
3011 | for example, @code{\008} has the value 010, and @code{\009} the value 011. | |
3012 | ||
3013 | @cindex @code{ \@var{xd...}} (hex character code) | |
3014 | @cindex hex character code (@code{\@var{xd...}}) | |
3015 | @item \@code{x} @var{hex-digits...} | |
3016 | A hex character code. All trailing hex digits are combined. Either upper or | |
3017 | lower case @code{x} works. | |
3018 | ||
3019 | @cindex @code{ \\} (@samp{\} character) | |
3020 | @cindex backslash (@code{\\}) | |
3021 | @item \\ | |
3022 | Represents one @samp{\} character. | |
3023 | ||
3024 | @c @item \' | |
3025 | @c Represents one @samp{'} (accent acute) character. | |
3026 | @c This is needed in single character literals | |
3027 | @c (@xref{Characters,,Character Constants}.) to represent | |
3028 | @c a @samp{'}. | |
3029 | @c | |
3030 | @cindex @code{ \"} (doublequote character) | |
3031 | @cindex doublequote (@code{\"}) | |
3032 | @item \" | |
3033 | Represents one @samp{"} character. Needed in strings to represent | |
3034 | this character, because an unescaped @samp{"} would end the string. | |
3035 | ||
3036 | @item \ @var{anything-else} | |
3037 | Any other character when escaped by @kbd{\} gives a warning, but | |
3038 | assembles as if the @samp{\} was not present. The idea is that if | |
3039 | you used an escape sequence you clearly didn't want the literal | |
3040 | interpretation of the following character. However @command{@value{AS}} has no | |
3041 | other interpretation, so @command{@value{AS}} knows it is giving you the wrong | |
3042 | code and warns you of the fact. | |
3043 | @end table | |
3044 | ||
3045 | Which characters are escapable, and what those escapes represent, | |
3046 | varies widely among assemblers. The current set is what we think | |
3047 | the BSD 4.2 assembler recognizes, and is a subset of what most C | |
3048 | compilers recognize. If you are in doubt, do not use an escape | |
3049 | sequence. | |
3050 | ||
3051 | @node Chars | |
3052 | @subsubsection Characters | |
3053 | ||
3054 | @cindex single character constant | |
3055 | @cindex character, single | |
3056 | @cindex constant, single character | |
3057 | A single character may be written as a single quote immediately followed by | |
3058 | that character. Some backslash escapes apply to characters, @code{\b}, | |
3059 | @code{\f}, @code{\n}, @code{\r}, @code{\t}, and @code{\"} with the same meaning | |
3060 | as for strings, plus @code{\'} for a single quote. So if you want to write the | |
3061 | character backslash, you must write @kbd{'\\} where the first @code{\} escapes | |
3062 | the second @code{\}. As you can see, the quote is an acute accent, not a grave | |
3063 | accent. A newline | |
3064 | @ifclear GENERIC | |
3065 | @ifclear abnormal-separator | |
3066 | (or semicolon @samp{;}) | |
3067 | @end ifclear | |
3068 | @ifset abnormal-separator | |
3069 | @ifset H8 | |
3070 | (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the | |
3071 | Renesas SH) | |
3072 | @end ifset | |
3073 | @end ifset | |
3074 | @end ifclear | |
3075 | immediately following an acute accent is taken as a literal character | |
3076 | and does not count as the end of a statement. The value of a character | |
3077 | constant in a numeric expression is the machine's byte-wide code for | |
3078 | that character. @command{@value{AS}} assumes your character code is ASCII: | |
3079 | @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill | |
3080 | ||
3081 | @node Numbers | |
3082 | @subsection Number Constants | |
3083 | ||
3084 | @cindex constants, number | |
3085 | @cindex number constants | |
3086 | @command{@value{AS}} distinguishes three kinds of numbers according to how they | |
3087 | are stored in the target machine. @emph{Integers} are numbers that | |
3088 | would fit into an @code{int} in the C language. @emph{Bignums} are | |
3089 | integers, but they are stored in more than 32 bits. @emph{Flonums} | |
3090 | are floating point numbers, described below. | |
3091 | ||
3092 | @menu | |
3093 | * Integers:: Integers | |
3094 | * Bignums:: Bignums | |
3095 | * Flonums:: Flonums | |
3096 | @ifclear GENERIC | |
3097 | @end ifclear | |
3098 | @end menu | |
3099 | ||
3100 | @node Integers | |
3101 | @subsubsection Integers | |
3102 | @cindex integers | |
3103 | @cindex constants, integer | |
3104 | ||
3105 | @cindex binary integers | |
3106 | @cindex integers, binary | |
3107 | A binary integer is @samp{0b} or @samp{0B} followed by zero or more of | |
3108 | the binary digits @samp{01}. | |
3109 | ||
3110 | @cindex octal integers | |
3111 | @cindex integers, octal | |
3112 | An octal integer is @samp{0} followed by zero or more of the octal | |
3113 | digits (@samp{01234567}). | |
3114 | ||
3115 | @cindex decimal integers | |
3116 | @cindex integers, decimal | |
3117 | A decimal integer starts with a non-zero digit followed by zero or | |
3118 | more digits (@samp{0123456789}). | |
3119 | ||
3120 | @cindex hexadecimal integers | |
3121 | @cindex integers, hexadecimal | |
3122 | A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or | |
3123 | more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}. | |
3124 | ||
3125 | Integers have the usual values. To denote a negative integer, use | |
3126 | the prefix operator @samp{-} discussed under expressions | |
3127 | (@pxref{Prefix Ops,,Prefix Operators}). | |
3128 | ||
3129 | @node Bignums | |
3130 | @subsubsection Bignums | |
3131 | ||
3132 | @cindex bignums | |
3133 | @cindex constants, bignum | |
3134 | A @dfn{bignum} has the same syntax and semantics as an integer | |
3135 | except that the number (or its negative) takes more than 32 bits to | |
3136 | represent in binary. The distinction is made because in some places | |
3137 | integers are permitted while bignums are not. | |
3138 | ||
3139 | @node Flonums | |
3140 | @subsubsection Flonums | |
3141 | @cindex flonums | |
3142 | @cindex floating point numbers | |
3143 | @cindex constants, floating point | |
3144 | ||
3145 | @cindex precision, floating point | |
3146 | A @dfn{flonum} represents a floating point number. The translation is | |
3147 | indirect: a decimal floating point number from the text is converted by | |
3148 | @command{@value{AS}} to a generic binary floating point number of more than | |
3149 | sufficient precision. This generic floating point number is converted | |
3150 | to a particular computer's floating point format (or formats) by a | |
3151 | portion of @command{@value{AS}} specialized to that computer. | |
3152 | ||
3153 | A flonum is written by writing (in order) | |
3154 | @itemize @bullet | |
3155 | @item | |
3156 | The digit @samp{0}. | |
3157 | @ifset HPPA | |
3158 | (@samp{0} is optional on the HPPA.) | |
3159 | @end ifset | |
3160 | ||
3161 | @item | |
3162 | A letter, to tell @command{@value{AS}} the rest of the number is a flonum. | |
3163 | @ifset GENERIC | |
3164 | @kbd{e} is recommended. Case is not important. | |
3165 | @ignore | |
3166 | @c FIXME: verify if flonum syntax really this vague for most cases | |
3167 | (Any otherwise illegal letter works here, but that might be changed. Vax BSD | |
3168 | 4.2 assembler seems to allow any of @samp{defghDEFGH}.) | |
3169 | @end ignore | |
3170 | ||
3171 | On the H8/300 and Renesas / SuperH SH architectures, the letter must be | |
3172 | one of the letters @samp{DFPRSX} (in upper or lower case). | |
3173 | ||
3174 | On the ARC, the letter must be one of the letters @samp{DFRS} | |
3175 | (in upper or lower case). | |
3176 | ||
3177 | On the HPPA architecture, the letter must be @samp{E} (upper case only). | |
3178 | @end ifset | |
3179 | @ifclear GENERIC | |
3180 | @ifset ARC | |
3181 | One of the letters @samp{DFRS} (in upper or lower case). | |
3182 | @end ifset | |
3183 | @ifset H8 | |
3184 | One of the letters @samp{DFPRSX} (in upper or lower case). | |
3185 | @end ifset | |
3186 | @ifset HPPA | |
3187 | The letter @samp{E} (upper case only). | |
3188 | @end ifset | |
3189 | @end ifclear | |
3190 | ||
3191 | @item | |
3192 | An optional sign: either @samp{+} or @samp{-}. | |
3193 | ||
3194 | @item | |
3195 | An optional @dfn{integer part}: zero or more decimal digits. | |
3196 | ||
3197 | @item | |
3198 | An optional @dfn{fractional part}: @samp{.} followed by zero | |
3199 | or more decimal digits. | |
3200 | ||
3201 | @item | |
3202 | An optional exponent, consisting of: | |
3203 | ||
3204 | @itemize @bullet | |
3205 | @item | |
3206 | An @samp{E} or @samp{e}. | |
3207 | @c I can't find a config where "EXP_CHARS" is other than 'eE', but in | |
3208 | @c principle this can perfectly well be different on different targets. | |
3209 | @item | |
3210 | Optional sign: either @samp{+} or @samp{-}. | |
3211 | @item | |
3212 | One or more decimal digits. | |
3213 | @end itemize | |
3214 | ||
3215 | @end itemize | |
3216 | ||
3217 | At least one of the integer part or the fractional part must be | |
3218 | present. The floating point number has the usual base-10 value. | |
3219 | ||
3220 | @command{@value{AS}} does all processing using integers. Flonums are computed | |
3221 | independently of any floating point hardware in the computer running | |
3222 | @command{@value{AS}}. | |
3223 | ||
3224 | @node Sections | |
3225 | @chapter Sections and Relocation | |
3226 | @cindex sections | |
3227 | @cindex relocation | |
3228 | ||
3229 | @menu | |
3230 | * Secs Background:: Background | |
3231 | * Ld Sections:: Linker Sections | |
3232 | * As Sections:: Assembler Internal Sections | |
3233 | * Sub-Sections:: Sub-Sections | |
3234 | * bss:: bss Section | |
3235 | @end menu | |
3236 | ||
3237 | @node Secs Background | |
3238 | @section Background | |
3239 | ||
3240 | Roughly, a section is a range of addresses, with no gaps; all data | |
3241 | ``in'' those addresses is treated the same for some particular purpose. | |
3242 | For example there may be a ``read only'' section. | |
3243 | ||
3244 | @cindex linker, and assembler | |
3245 | @cindex assembler, and linker | |
3246 | The linker @code{@value{LD}} reads many object files (partial programs) and | |
3247 | combines their contents to form a runnable program. When @command{@value{AS}} | |
3248 | emits an object file, the partial program is assumed to start at address 0. | |
3249 | @code{@value{LD}} assigns the final addresses for the partial program, so that | |
3250 | different partial programs do not overlap. This is actually an | |
3251 | oversimplification, but it suffices to explain how @command{@value{AS}} uses | |
3252 | sections. | |
3253 | ||
3254 | @code{@value{LD}} moves blocks of bytes of your program to their run-time | |
3255 | addresses. These blocks slide to their run-time addresses as rigid | |
3256 | units; their length does not change and neither does the order of bytes | |
3257 | within them. Such a rigid unit is called a @emph{section}. Assigning | |
3258 | run-time addresses to sections is called @dfn{relocation}. It includes | |
3259 | the task of adjusting mentions of object-file addresses so they refer to | |
3260 | the proper run-time addresses. | |
3261 | @ifset H8 | |
3262 | For the H8/300, and for the Renesas / SuperH SH, | |
3263 | @command{@value{AS}} pads sections if needed to | |
3264 | ensure they end on a word (sixteen bit) boundary. | |
3265 | @end ifset | |
3266 | ||
3267 | @cindex standard assembler sections | |
3268 | An object file written by @command{@value{AS}} has at least three sections, any | |
3269 | of which may be empty. These are named @dfn{text}, @dfn{data} and | |
3270 | @dfn{bss} sections. | |
3271 | ||
3272 | @ifset COFF-ELF | |
3273 | @ifset GENERIC | |
3274 | When it generates COFF or ELF output, | |
3275 | @end ifset | |
3276 | @command{@value{AS}} can also generate whatever other named sections you specify | |
3277 | using the @samp{.section} directive (@pxref{Section,,@code{.section}}). | |
3278 | If you do not use any directives that place output in the @samp{.text} | |
3279 | or @samp{.data} sections, these sections still exist, but are empty. | |
3280 | @end ifset | |
3281 | ||
3282 | @ifset HPPA | |
3283 | @ifset GENERIC | |
3284 | When @command{@value{AS}} generates SOM or ELF output for the HPPA, | |
3285 | @end ifset | |
3286 | @command{@value{AS}} can also generate whatever other named sections you | |
3287 | specify using the @samp{.space} and @samp{.subspace} directives. See | |
3288 | @cite{HP9000 Series 800 Assembly Language Reference Manual} | |
3289 | (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace} | |
3290 | assembler directives. | |
3291 | ||
3292 | @ifset SOM | |
3293 | Additionally, @command{@value{AS}} uses different names for the standard | |
3294 | text, data, and bss sections when generating SOM output. Program text | |
3295 | is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and | |
3296 | BSS into @samp{$BSS$}. | |
3297 | @end ifset | |
3298 | @end ifset | |
3299 | ||
3300 | Within the object file, the text section starts at address @code{0}, the | |
3301 | data section follows, and the bss section follows the data section. | |
3302 | ||
3303 | @ifset HPPA | |
3304 | When generating either SOM or ELF output files on the HPPA, the text | |
3305 | section starts at address @code{0}, the data section at address | |
3306 | @code{0x4000000}, and the bss section follows the data section. | |
3307 | @end ifset | |
3308 | ||
3309 | To let @code{@value{LD}} know which data changes when the sections are | |
3310 | relocated, and how to change that data, @command{@value{AS}} also writes to the | |
3311 | object file details of the relocation needed. To perform relocation | |
3312 | @code{@value{LD}} must know, each time an address in the object | |
3313 | file is mentioned: | |
3314 | @itemize @bullet | |
3315 | @item | |
3316 | Where in the object file is the beginning of this reference to | |
3317 | an address? | |
3318 | @item | |
3319 | How long (in bytes) is this reference? | |
3320 | @item | |
3321 | Which section does the address refer to? What is the numeric value of | |
3322 | @display | |
3323 | (@var{address}) @minus{} (@var{start-address of section})? | |
3324 | @end display | |
3325 | @item | |
3326 | Is the reference to an address ``Program-Counter relative''? | |
3327 | @end itemize | |
3328 | ||
3329 | @cindex addresses, format of | |
3330 | @cindex section-relative addressing | |
3331 | In fact, every address @command{@value{AS}} ever uses is expressed as | |
3332 | @display | |
3333 | (@var{section}) + (@var{offset into section}) | |
3334 | @end display | |
3335 | @noindent | |
3336 | Further, most expressions @command{@value{AS}} computes have this section-relative | |
3337 | nature. | |
3338 | @ifset SOM | |
3339 | (For some object formats, such as SOM for the HPPA, some expressions are | |
3340 | symbol-relative instead.) | |
3341 | @end ifset | |
3342 | ||
3343 | In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset | |
3344 | @var{N} into section @var{secname}.'' | |
3345 | ||
3346 | Apart from text, data and bss sections you need to know about the | |
3347 | @dfn{absolute} section. When @code{@value{LD}} mixes partial programs, | |
3348 | addresses in the absolute section remain unchanged. For example, address | |
3349 | @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by | |
3350 | @code{@value{LD}}. Although the linker never arranges two partial programs' | |
3351 | data sections with overlapping addresses after linking, @emph{by definition} | |
3352 | their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one | |
3353 | part of a program is always the same address when the program is running as | |
3354 | address @code{@{absolute@ 239@}} in any other part of the program. | |
3355 | ||
3356 | The idea of sections is extended to the @dfn{undefined} section. Any | |
3357 | address whose section is unknown at assembly time is by definition | |
3358 | rendered @{undefined @var{U}@}---where @var{U} is filled in later. | |
3359 | Since numbers are always defined, the only way to generate an undefined | |
3360 | address is to mention an undefined symbol. A reference to a named | |
3361 | common block would be such a symbol: its value is unknown at assembly | |
3362 | time so it has section @emph{undefined}. | |
3363 | ||
3364 | By analogy the word @emph{section} is used to describe groups of sections in | |
3365 | the linked program. @code{@value{LD}} puts all partial programs' text | |
3366 | sections in contiguous addresses in the linked program. It is | |
3367 | customary to refer to the @emph{text section} of a program, meaning all | |
3368 | the addresses of all partial programs' text sections. Likewise for | |
3369 | data and bss sections. | |
3370 | ||
3371 | Some sections are manipulated by @code{@value{LD}}; others are invented for | |
3372 | use of @command{@value{AS}} and have no meaning except during assembly. | |
3373 | ||
3374 | @node Ld Sections | |
3375 | @section Linker Sections | |
3376 | @code{@value{LD}} deals with just four kinds of sections, summarized below. | |
3377 | ||
3378 | @table @strong | |
3379 | ||
3380 | @ifset COFF-ELF | |
3381 | @cindex named sections | |
3382 | @cindex sections, named | |
3383 | @item named sections | |
3384 | @end ifset | |
3385 | @ifset aout | |
3386 | @cindex text section | |
3387 | @cindex data section | |
3388 | @itemx text section | |
3389 | @itemx data section | |
3390 | @end ifset | |
3391 | These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as | |
3392 | separate but equal sections. Anything you can say of one section is | |
3393 | true of another. | |
3394 | @c @ifset aout | |
3395 | When the program is running, however, it is | |
3396 | customary for the text section to be unalterable. The | |
3397 | text section is often shared among processes: it contains | |
3398 | instructions, constants and the like. The data section of a running | |
3399 | program is usually alterable: for example, C variables would be stored | |
3400 | in the data section. | |
3401 | @c @end ifset | |
3402 | ||
3403 | @cindex bss section | |
3404 | @item bss section | |
3405 | This section contains zeroed bytes when your program begins running. It | |
3406 | is used to hold uninitialized variables or common storage. The length of | |
3407 | each partial program's bss section is important, but because it starts | |
3408 | out containing zeroed bytes there is no need to store explicit zero | |
3409 | bytes in the object file. The bss section was invented to eliminate | |
3410 | those explicit zeros from object files. | |
3411 | ||
3412 | @cindex absolute section | |
3413 | @item absolute section | |
3414 | Address 0 of this section is always ``relocated'' to runtime address 0. | |
3415 | This is useful if you want to refer to an address that @code{@value{LD}} must | |
3416 | not change when relocating. In this sense we speak of absolute | |
3417 | addresses being ``unrelocatable'': they do not change during relocation. | |
3418 | ||
3419 | @cindex undefined section | |
3420 | @item undefined section | |
3421 | This ``section'' is a catch-all for address references to objects not in | |
3422 | the preceding sections. | |
3423 | @c FIXME: ref to some other doc on obj-file formats could go here. | |
3424 | @end table | |
3425 | ||
3426 | @cindex relocation example | |
3427 | An idealized example of three relocatable sections follows. | |
3428 | @ifset COFF-ELF | |
3429 | The example uses the traditional section names @samp{.text} and @samp{.data}. | |
3430 | @end ifset | |
3431 | Memory addresses are on the horizontal axis. | |
3432 | ||
3433 | @c TEXI2ROFF-KILL | |
3434 | @ifnottex | |
3435 | @c END TEXI2ROFF-KILL | |
3436 | @smallexample | |
3437 | +-----+----+--+ | |
3438 | partial program # 1: |ttttt|dddd|00| | |
3439 | +-----+----+--+ | |
3440 | ||
3441 | text data bss | |
3442 | seg. seg. seg. | |
3443 | ||
3444 | +---+---+---+ | |
3445 | partial program # 2: |TTT|DDD|000| | |
3446 | +---+---+---+ | |
3447 | ||
3448 | +--+---+-----+--+----+---+-----+~~ | |
3449 | linked program: | |TTT|ttttt| |dddd|DDD|00000| | |
3450 | +--+---+-----+--+----+---+-----+~~ | |
3451 | ||
3452 | addresses: 0 @dots{} | |
3453 | @end smallexample | |
3454 | @c TEXI2ROFF-KILL | |
3455 | @end ifnottex | |
3456 | @need 5000 | |
3457 | @tex | |
3458 | \bigskip | |
3459 | \line{\it Partial program \#1: \hfil} | |
3460 | \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} | |
3461 | \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil} | |
3462 | ||
3463 | \line{\it Partial program \#2: \hfil} | |
3464 | \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} | |
3465 | \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil} | |
3466 | ||
3467 | \line{\it linked program: \hfil} | |
3468 | \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil} | |
3469 | \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt | |
3470 | ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt | |
3471 | DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil} | |
3472 | ||
3473 | \line{\it addresses: \hfil} | |
3474 | \line{0\dots\hfil} | |
3475 | ||
3476 | @end tex | |
3477 | @c END TEXI2ROFF-KILL | |
3478 | ||
3479 | @node As Sections | |
3480 | @section Assembler Internal Sections | |
3481 | ||
3482 | @cindex internal assembler sections | |
3483 | @cindex sections in messages, internal | |
3484 | These sections are meant only for the internal use of @command{@value{AS}}. They | |
3485 | have no meaning at run-time. You do not really need to know about these | |
3486 | sections for most purposes; but they can be mentioned in @command{@value{AS}} | |
3487 | warning messages, so it might be helpful to have an idea of their | |
3488 | meanings to @command{@value{AS}}. These sections are used to permit the | |
3489 | value of every expression in your assembly language program to be a | |
3490 | section-relative address. | |
3491 | ||
3492 | @table @b | |
3493 | @cindex assembler internal logic error | |
3494 | @item ASSEMBLER-INTERNAL-LOGIC-ERROR! | |
3495 | An internal assembler logic error has been found. This means there is a | |
3496 | bug in the assembler. | |
3497 | ||
3498 | @cindex expr (internal section) | |
3499 | @item expr section | |
3500 | The assembler stores complex expression internally as combinations of | |
3501 | symbols. When it needs to represent an expression as a symbol, it puts | |
3502 | it in the expr section. | |
3503 | @c FIXME item debug | |
3504 | @c FIXME item transfer[t] vector preload | |
3505 | @c FIXME item transfer[t] vector postload | |
3506 | @c FIXME item register | |
3507 | @end table | |
3508 | ||
3509 | @node Sub-Sections | |
3510 | @section Sub-Sections | |
3511 | ||
3512 | @cindex numbered subsections | |
3513 | @cindex grouping data | |
3514 | @ifset aout | |
3515 | Assembled bytes | |
3516 | @ifset COFF-ELF | |
3517 | conventionally | |
3518 | @end ifset | |
3519 | fall into two sections: text and data. | |
3520 | @end ifset | |
3521 | You may have separate groups of | |
3522 | @ifset GENERIC | |
3523 | data in named sections | |
3524 | @end ifset | |
3525 | @ifclear GENERIC | |
3526 | @ifclear aout | |
3527 | data in named sections | |
3528 | @end ifclear | |
3529 | @ifset aout | |
3530 | text or data | |
3531 | @end ifset | |
3532 | @end ifclear | |
3533 | that you want to end up near to each other in the object file, even though they | |
3534 | are not contiguous in the assembler source. @command{@value{AS}} allows you to | |
3535 | use @dfn{subsections} for this purpose. Within each section, there can be | |
3536 | numbered subsections with values from 0 to 8192. Objects assembled into the | |
3537 | same subsection go into the object file together with other objects in the same | |
3538 | subsection. For example, a compiler might want to store constants in the text | |
3539 | section, but might not want to have them interspersed with the program being | |
3540 | assembled. In this case, the compiler could issue a @samp{.text 0} before each | |
3541 | section of code being output, and a @samp{.text 1} before each group of | |
3542 | constants being output. | |
3543 | ||
3544 | Subsections are optional. If you do not use subsections, everything | |
3545 | goes in subsection number zero. | |
3546 | ||
3547 | @ifset GENERIC | |
3548 | Each subsection is zero-padded up to a multiple of four bytes. | |
3549 | (Subsections may be padded a different amount on different flavors | |
3550 | of @command{@value{AS}}.) | |
3551 | @end ifset | |
3552 | @ifclear GENERIC | |
3553 | @ifset H8 | |
3554 | On the H8/300 platform, each subsection is zero-padded to a word | |
3555 | boundary (two bytes). | |
3556 | The same is true on the Renesas SH. | |
3557 | @end ifset | |
3558 | @end ifclear | |
3559 | ||
3560 | Subsections appear in your object file in numeric order, lowest numbered | |
3561 | to highest. (All this to be compatible with other people's assemblers.) | |
3562 | The object file contains no representation of subsections; @code{@value{LD}} and | |
3563 | other programs that manipulate object files see no trace of them. | |
3564 | They just see all your text subsections as a text section, and all your | |
3565 | data subsections as a data section. | |
3566 | ||
3567 | To specify which subsection you want subsequent statements assembled | |
3568 | into, use a numeric argument to specify it, in a @samp{.text | |
3569 | @var{expression}} or a @samp{.data @var{expression}} statement. | |
3570 | @ifset COFF | |
3571 | @ifset GENERIC | |
3572 | When generating COFF output, you | |
3573 | @end ifset | |
3574 | @ifclear GENERIC | |
3575 | You | |
3576 | @end ifclear | |
3577 | can also use an extra subsection | |
3578 | argument with arbitrary named sections: @samp{.section @var{name}, | |
3579 | @var{expression}}. | |
3580 | @end ifset | |
3581 | @ifset ELF | |
3582 | @ifset GENERIC | |
3583 | When generating ELF output, you | |
3584 | @end ifset | |
3585 | @ifclear GENERIC | |
3586 | You | |
3587 | @end ifclear | |
3588 | can also use the @code{.subsection} directive (@pxref{SubSection}) | |
3589 | to specify a subsection: @samp{.subsection @var{expression}}. | |
3590 | @end ifset | |
3591 | @var{Expression} should be an absolute expression | |
3592 | (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0} | |
3593 | is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly | |
3594 | begins in @code{text 0}. For instance: | |
3595 | @smallexample | |
3596 | .text 0 # The default subsection is text 0 anyway. | |
3597 | .ascii "This lives in the first text subsection. *" | |
3598 | .text 1 | |
3599 | .ascii "But this lives in the second text subsection." | |
3600 | .data 0 | |
3601 | .ascii "This lives in the data section," | |
3602 | .ascii "in the first data subsection." | |
3603 | .text 0 | |
3604 | .ascii "This lives in the first text section," | |
3605 | .ascii "immediately following the asterisk (*)." | |
3606 | @end smallexample | |
3607 | ||
3608 | Each section has a @dfn{location counter} incremented by one for every byte | |
3609 | assembled into that section. Because subsections are merely a convenience | |
3610 | restricted to @command{@value{AS}} there is no concept of a subsection location | |
3611 | counter. There is no way to directly manipulate a location counter---but the | |
3612 | @code{.align} directive changes it, and any label definition captures its | |
3613 | current value. The location counter of the section where statements are being | |
3614 | assembled is said to be the @dfn{active} location counter. | |
3615 | ||
3616 | @node bss | |
3617 | @section bss Section | |
3618 | ||
3619 | @cindex bss section | |
3620 | @cindex common variable storage | |
3621 | The bss section is used for local common variable storage. | |
3622 | You may allocate address space in the bss section, but you may | |
3623 | not dictate data to load into it before your program executes. When | |
3624 | your program starts running, all the contents of the bss | |
3625 | section are zeroed bytes. | |
3626 | ||
3627 | The @code{.lcomm} pseudo-op defines a symbol in the bss section; see | |
3628 | @ref{Lcomm,,@code{.lcomm}}. | |
3629 | ||
3630 | The @code{.comm} pseudo-op may be used to declare a common symbol, which is | |
3631 | another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}. | |
3632 | ||
3633 | @ifset GENERIC | |
3634 | When assembling for a target which supports multiple sections, such as ELF or | |
3635 | COFF, you may switch into the @code{.bss} section and define symbols as usual; | |
3636 | see @ref{Section,,@code{.section}}. You may only assemble zero values into the | |
3637 | section. Typically the section will only contain symbol definitions and | |
3638 | @code{.skip} directives (@pxref{Skip,,@code{.skip}}). | |
3639 | @end ifset | |
3640 | ||
3641 | @node Symbols | |
3642 | @chapter Symbols | |
3643 | ||
3644 | @cindex symbols | |
3645 | Symbols are a central concept: the programmer uses symbols to name | |
3646 | things, the linker uses symbols to link, and the debugger uses symbols | |
3647 | to debug. | |
3648 | ||
3649 | @quotation | |
3650 | @cindex debuggers, and symbol order | |
3651 | @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in | |
3652 | the same order they were declared. This may break some debuggers. | |
3653 | @end quotation | |
3654 | ||
3655 | @menu | |
3656 | * Labels:: Labels | |
3657 | * Setting Symbols:: Giving Symbols Other Values | |
3658 | * Symbol Names:: Symbol Names | |
3659 | * Dot:: The Special Dot Symbol | |
3660 | * Symbol Attributes:: Symbol Attributes | |
3661 | @end menu | |
3662 | ||
3663 | @node Labels | |
3664 | @section Labels | |
3665 | ||
3666 | @cindex labels | |
3667 | A @dfn{label} is written as a symbol immediately followed by a colon | |
3668 | @samp{:}. The symbol then represents the current value of the | |
3669 | active location counter, and is, for example, a suitable instruction | |
3670 | operand. You are warned if you use the same symbol to represent two | |
3671 | different locations: the first definition overrides any other | |
3672 | definitions. | |
3673 | ||
3674 | @ifset HPPA | |
3675 | On the HPPA, the usual form for a label need not be immediately followed by a | |
3676 | colon, but instead must start in column zero. Only one label may be defined on | |
3677 | a single line. To work around this, the HPPA version of @command{@value{AS}} also | |
3678 | provides a special directive @code{.label} for defining labels more flexibly. | |
3679 | @end ifset | |
3680 | ||
3681 | @node Setting Symbols | |
3682 | @section Giving Symbols Other Values | |
3683 | ||
3684 | @cindex assigning values to symbols | |
3685 | @cindex symbol values, assigning | |
3686 | A symbol can be given an arbitrary value by writing a symbol, followed | |
3687 | by an equals sign @samp{=}, followed by an expression | |
3688 | (@pxref{Expressions}). This is equivalent to using the @code{.set} | |
3689 | directive. @xref{Set,,@code{.set}}. In the same way, using a double | |
3690 | equals sign @samp{=}@samp{=} here represents an equivalent of the | |
3691 | @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}. | |
3692 | ||
3693 | @ifset Blackfin | |
3694 | Blackfin does not support symbol assignment with @samp{=}. | |
3695 | @end ifset | |
3696 | ||
3697 | @node Symbol Names | |
3698 | @section Symbol Names | |
3699 | ||
3700 | @cindex symbol names | |
3701 | @cindex names, symbol | |
3702 | @ifclear SPECIAL-SYMS | |
3703 | Symbol names begin with a letter or with one of @samp{._}. On most | |
3704 | machines, you can also use @code{$} in symbol names; exceptions are | |
3705 | noted in @ref{Machine Dependencies}. That character may be followed by any | |
3706 | string of digits, letters, dollar signs (unless otherwise noted for a | |
3707 | particular target machine), and underscores. | |
3708 | @end ifclear | |
3709 | @ifset SPECIAL-SYMS | |
3710 | @ifset H8 | |
3711 | Symbol names begin with a letter or with one of @samp{._}. On the | |
3712 | Renesas SH you can also use @code{$} in symbol names. That | |
3713 | character may be followed by any string of digits, letters, dollar signs (save | |
3714 | on the H8/300), and underscores. | |
3715 | @end ifset | |
3716 | @end ifset | |
3717 | ||
3718 | Case of letters is significant: @code{foo} is a different symbol name | |
3719 | than @code{Foo}. | |
3720 | ||
3721 | Symbol names do not start with a digit. An exception to this rule is made for | |
3722 | Local Labels. See below. | |
3723 | ||
3724 | Multibyte characters are supported. To generate a symbol name containing | |
3725 | multibyte characters enclose it within double quotes and use escape codes. cf | |
3726 | @xref{Strings}. Generating a multibyte symbol name from a label is not | |
3727 | currently supported. | |
3728 | ||
3729 | Each symbol has exactly one name. Each name in an assembly language program | |
3730 | refers to exactly one symbol. You may use that symbol name any number of times | |
3731 | in a program. | |
3732 | ||
3733 | @subheading Local Symbol Names | |
3734 | ||
3735 | @cindex local symbol names | |
3736 | @cindex symbol names, local | |
3737 | A local symbol is any symbol beginning with certain local label prefixes. | |
3738 | By default, the local label prefix is @samp{.L} for ELF systems or | |
3739 | @samp{L} for traditional a.out systems, but each target may have its own | |
3740 | set of local label prefixes. | |
3741 | @ifset HPPA | |
3742 | On the HPPA local symbols begin with @samp{L$}. | |
3743 | @end ifset | |
3744 | ||
3745 | Local symbols are defined and used within the assembler, but they are | |
3746 | normally not saved in object files. Thus, they are not visible when debugging. | |
3747 | You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols}) | |
3748 | to retain the local symbols in the object files. | |
3749 | ||
3750 | @subheading Local Labels | |
3751 | ||
3752 | @cindex local labels | |
3753 | @cindex temporary symbol names | |
3754 | @cindex symbol names, temporary | |
3755 | Local labels are different from local symbols. Local labels help compilers and | |
3756 | programmers use names temporarily. They create symbols which are guaranteed to | |
3757 | be unique over the entire scope of the input source code and which can be | |
3758 | referred to by a simple notation. To define a local label, write a label of | |
3759 | the form @samp{@b{N}:} (where @b{N} represents any non-negative integer). | |
3760 | To refer to the most recent previous definition of that label write | |
3761 | @samp{@b{N}b}, using the same number as when you defined the label. To refer | |
3762 | to the next definition of a local label, write @samp{@b{N}f}. The @samp{b} | |
3763 | stands for ``backwards'' and the @samp{f} stands for ``forwards''. | |
3764 | ||
3765 | There is no restriction on how you can use these labels, and you can reuse them | |
3766 | too. So that it is possible to repeatedly define the same local label (using | |
3767 | the same number @samp{@b{N}}), although you can only refer to the most recently | |
3768 | defined local label of that number (for a backwards reference) or the next | |
3769 | definition of a specific local label for a forward reference. It is also worth | |
3770 | noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are | |
3771 | implemented in a slightly more efficient manner than the others. | |
3772 | ||
3773 | Here is an example: | |
3774 | ||
3775 | @smallexample | |
3776 | 1: branch 1f | |
3777 | 2: branch 1b | |
3778 | 1: branch 2f | |
3779 | 2: branch 1b | |
3780 | @end smallexample | |
3781 | ||
3782 | Which is the equivalent of: | |
3783 | ||
3784 | @smallexample | |
3785 | label_1: branch label_3 | |
3786 | label_2: branch label_1 | |
3787 | label_3: branch label_4 | |
3788 | label_4: branch label_3 | |
3789 | @end smallexample | |
3790 | ||
3791 | Local label names are only a notational device. They are immediately | |
3792 | transformed into more conventional symbol names before the assembler uses them. | |
3793 | The symbol names are stored in the symbol table, appear in error messages, and | |
3794 | are optionally emitted to the object file. The names are constructed using | |
3795 | these parts: | |
3796 | ||
3797 | @table @code | |
3798 | @item @emph{local label prefix} | |
3799 | All local symbols begin with the system-specific local label prefix. | |
3800 | Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols | |
3801 | that start with the local label prefix. These labels are | |
3802 | used for symbols you are never intended to see. If you use the | |
3803 | @samp{-L} option then @command{@value{AS}} retains these symbols in the | |
3804 | object file. If you also instruct @code{@value{LD}} to retain these symbols, | |
3805 | you may use them in debugging. | |
3806 | ||
3807 | @item @var{number} | |
3808 | This is the number that was used in the local label definition. So if the | |
3809 | label is written @samp{55:} then the number is @samp{55}. | |
3810 | ||
3811 | @item @kbd{C-B} | |
3812 | This unusual character is included so you do not accidentally invent a symbol | |
3813 | of the same name. The character has ASCII value of @samp{\002} (control-B). | |
3814 | ||
3815 | @item @emph{ordinal number} | |
3816 | This is a serial number to keep the labels distinct. The first definition of | |
3817 | @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the | |
3818 | number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets | |
3819 | the number @samp{1} and its 15th definition gets @samp{15} as well. | |
3820 | @end table | |
3821 | ||
3822 | So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and | |
3823 | the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}. | |
3824 | ||
3825 | @subheading Dollar Local Labels | |
3826 | @cindex dollar local symbols | |
3827 | ||
3828 | On some targets @code{@value{AS}} also supports an even more local form of | |
3829 | local labels called dollar labels. These labels go out of scope (i.e., they | |
3830 | become undefined) as soon as a non-local label is defined. Thus they remain | |
3831 | valid for only a small region of the input source code. Normal local labels, | |
3832 | by contrast, remain in scope for the entire file, or until they are redefined | |
3833 | by another occurrence of the same local label. | |
3834 | ||
3835 | Dollar labels are defined in exactly the same way as ordinary local labels, | |
3836 | except that they have a dollar sign suffix to their numeric value, e.g., | |
3837 | @samp{@b{55$:}}. | |
3838 | ||
3839 | They can also be distinguished from ordinary local labels by their transformed | |
3840 | names which use ASCII character @samp{\001} (control-A) as the magic character | |
3841 | to distinguish them from ordinary labels. For example, the fifth definition of | |
3842 | @samp{6$} may be named @samp{.L6@kbd{C-A}5}. | |
3843 | ||
3844 | @node Dot | |
3845 | @section The Special Dot Symbol | |
3846 | ||
3847 | @cindex dot (symbol) | |
3848 | @cindex @code{.} (symbol) | |
3849 | @cindex current address | |
3850 | @cindex location counter | |
3851 | The special symbol @samp{.} refers to the current address that | |
3852 | @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin: | |
3853 | .long .} defines @code{melvin} to contain its own address. | |
3854 | Assigning a value to @code{.} is treated the same as a @code{.org} | |
3855 | directive. | |
3856 | @ifclear no-space-dir | |
3857 | Thus, the expression @samp{.=.+4} is the same as saying | |
3858 | @samp{.space 4}. | |
3859 | @end ifclear | |
3860 | ||
3861 | @node Symbol Attributes | |
3862 | @section Symbol Attributes | |
3863 | ||
3864 | @cindex symbol attributes | |
3865 | @cindex attributes, symbol | |
3866 | Every symbol has, as well as its name, the attributes ``Value'' and | |
3867 | ``Type''. Depending on output format, symbols can also have auxiliary | |
3868 | attributes. | |
3869 | @ifset INTERNALS | |
3870 | The detailed definitions are in @file{a.out.h}. | |
3871 | @end ifset | |
3872 | ||
3873 | If you use a symbol without defining it, @command{@value{AS}} assumes zero for | |
3874 | all these attributes, and probably won't warn you. This makes the | |
3875 | symbol an externally defined symbol, which is generally what you | |
3876 | would want. | |
3877 | ||
3878 | @menu | |
3879 | * Symbol Value:: Value | |
3880 | * Symbol Type:: Type | |
3881 | @ifset aout | |
3882 | * a.out Symbols:: Symbol Attributes: @code{a.out} | |
3883 | @end ifset | |
3884 | @ifset COFF | |
3885 | * COFF Symbols:: Symbol Attributes for COFF | |
3886 | @end ifset | |
3887 | @ifset SOM | |
3888 | * SOM Symbols:: Symbol Attributes for SOM | |
3889 | @end ifset | |
3890 | @end menu | |
3891 | ||
3892 | @node Symbol Value | |
3893 | @subsection Value | |
3894 | ||
3895 | @cindex value of a symbol | |
3896 | @cindex symbol value | |
3897 | The value of a symbol is (usually) 32 bits. For a symbol which labels a | |
3898 | location in the text, data, bss or absolute sections the value is the | |
3899 | number of addresses from the start of that section to the label. | |
3900 | Naturally for text, data and bss sections the value of a symbol changes | |
3901 | as @code{@value{LD}} changes section base addresses during linking. Absolute | |
3902 | symbols' values do not change during linking: that is why they are | |
3903 | called absolute. | |
3904 | ||
3905 | The value of an undefined symbol is treated in a special way. If it is | |
3906 | 0 then the symbol is not defined in this assembler source file, and | |
3907 | @code{@value{LD}} tries to determine its value from other files linked into the | |
3908 | same program. You make this kind of symbol simply by mentioning a symbol | |
3909 | name without defining it. A non-zero value represents a @code{.comm} | |
3910 | common declaration. The value is how much common storage to reserve, in | |
3911 | bytes (addresses). The symbol refers to the first address of the | |
3912 | allocated storage. | |
3913 | ||
3914 | @node Symbol Type | |
3915 | @subsection Type | |
3916 | ||
3917 | @cindex type of a symbol | |
3918 | @cindex symbol type | |
3919 | The type attribute of a symbol contains relocation (section) | |
3920 | information, any flag settings indicating that a symbol is external, and | |
3921 | (optionally), other information for linkers and debuggers. The exact | |
3922 | format depends on the object-code output format in use. | |
3923 | ||
3924 | @ifset aout | |
3925 | @node a.out Symbols | |
3926 | @subsection Symbol Attributes: @code{a.out} | |
3927 | ||
3928 | @cindex @code{a.out} symbol attributes | |
3929 | @cindex symbol attributes, @code{a.out} | |
3930 | ||
3931 | @menu | |
3932 | * Symbol Desc:: Descriptor | |
3933 | * Symbol Other:: Other | |
3934 | @end menu | |
3935 | ||
3936 | @node Symbol Desc | |
3937 | @subsubsection Descriptor | |
3938 | ||
3939 | @cindex descriptor, of @code{a.out} symbol | |
3940 | This is an arbitrary 16-bit value. You may establish a symbol's | |
3941 | descriptor value by using a @code{.desc} statement | |
3942 | (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to | |
3943 | @command{@value{AS}}. | |
3944 | ||
3945 | @node Symbol Other | |
3946 | @subsubsection Other | |
3947 | ||
3948 | @cindex other attribute, of @code{a.out} symbol | |
3949 | This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}. | |
3950 | @end ifset | |
3951 | ||
3952 | @ifset COFF | |
3953 | @node COFF Symbols | |
3954 | @subsection Symbol Attributes for COFF | |
3955 | ||
3956 | @cindex COFF symbol attributes | |
3957 | @cindex symbol attributes, COFF | |
3958 | ||
3959 | The COFF format supports a multitude of auxiliary symbol attributes; | |
3960 | like the primary symbol attributes, they are set between @code{.def} and | |
3961 | @code{.endef} directives. | |
3962 | ||
3963 | @subsubsection Primary Attributes | |
3964 | ||
3965 | @cindex primary attributes, COFF symbols | |
3966 | The symbol name is set with @code{.def}; the value and type, | |
3967 | respectively, with @code{.val} and @code{.type}. | |
3968 | ||
3969 | @subsubsection Auxiliary Attributes | |
3970 | ||
3971 | @cindex auxiliary attributes, COFF symbols | |
3972 | The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl}, | |
3973 | @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol | |
3974 | table information for COFF. | |
3975 | @end ifset | |
3976 | ||
3977 | @ifset SOM | |
3978 | @node SOM Symbols | |
3979 | @subsection Symbol Attributes for SOM | |
3980 | ||
3981 | @cindex SOM symbol attributes | |
3982 | @cindex symbol attributes, SOM | |
3983 | ||
3984 | The SOM format for the HPPA supports a multitude of symbol attributes set with | |
3985 | the @code{.EXPORT} and @code{.IMPORT} directives. | |
3986 | ||
3987 | The attributes are described in @cite{HP9000 Series 800 Assembly | |
3988 | Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and | |
3989 | @code{EXPORT} assembler directive documentation. | |
3990 | @end ifset | |
3991 | ||
3992 | @node Expressions | |
3993 | @chapter Expressions | |
3994 | ||
3995 | @cindex expressions | |
3996 | @cindex addresses | |
3997 | @cindex numeric values | |
3998 | An @dfn{expression} specifies an address or numeric value. | |
3999 | Whitespace may precede and/or follow an expression. | |
4000 | ||
4001 | The result of an expression must be an absolute number, or else an offset into | |
4002 | a particular section. If an expression is not absolute, and there is not | |
4003 | enough information when @command{@value{AS}} sees the expression to know its | |
4004 | section, a second pass over the source program might be necessary to interpret | |
4005 | the expression---but the second pass is currently not implemented. | |
4006 | @command{@value{AS}} aborts with an error message in this situation. | |
4007 | ||
4008 | @menu | |
4009 | * Empty Exprs:: Empty Expressions | |
4010 | * Integer Exprs:: Integer Expressions | |
4011 | @end menu | |
4012 | ||
4013 | @node Empty Exprs | |
4014 | @section Empty Expressions | |
4015 | ||
4016 | @cindex empty expressions | |
4017 | @cindex expressions, empty | |
4018 | An empty expression has no value: it is just whitespace or null. | |
4019 | Wherever an absolute expression is required, you may omit the | |
4020 | expression, and @command{@value{AS}} assumes a value of (absolute) 0. This | |
4021 | is compatible with other assemblers. | |
4022 | ||
4023 | @node Integer Exprs | |
4024 | @section Integer Expressions | |
4025 | ||
4026 | @cindex integer expressions | |
4027 | @cindex expressions, integer | |
4028 | An @dfn{integer expression} is one or more @emph{arguments} delimited | |
4029 | by @emph{operators}. | |
4030 | ||
4031 | @menu | |
4032 | * Arguments:: Arguments | |
4033 | * Operators:: Operators | |
4034 | * Prefix Ops:: Prefix Operators | |
4035 | * Infix Ops:: Infix Operators | |
4036 | @end menu | |
4037 | ||
4038 | @node Arguments | |
4039 | @subsection Arguments | |
4040 | ||
4041 | @cindex expression arguments | |
4042 | @cindex arguments in expressions | |
4043 | @cindex operands in expressions | |
4044 | @cindex arithmetic operands | |
4045 | @dfn{Arguments} are symbols, numbers or subexpressions. In other | |
4046 | contexts arguments are sometimes called ``arithmetic operands''. In | |
4047 | this manual, to avoid confusing them with the ``instruction operands'' of | |
4048 | the machine language, we use the term ``argument'' to refer to parts of | |
4049 | expressions only, reserving the word ``operand'' to refer only to machine | |
4050 | instruction operands. | |
4051 | ||
4052 | Symbols are evaluated to yield @{@var{section} @var{NNN}@} where | |
4053 | @var{section} is one of text, data, bss, absolute, | |
4054 | or undefined. @var{NNN} is a signed, 2's complement 32 bit | |
4055 | integer. | |
4056 | ||
4057 | Numbers are usually integers. | |
4058 | ||
4059 | A number can be a flonum or bignum. In this case, you are warned | |
4060 | that only the low order 32 bits are used, and @command{@value{AS}} pretends | |
4061 | these 32 bits are an integer. You may write integer-manipulating | |
4062 | instructions that act on exotic constants, compatible with other | |
4063 | assemblers. | |
4064 | ||
4065 | @cindex subexpressions | |
4066 | Subexpressions are a left parenthesis @samp{(} followed by an integer | |
4067 | expression, followed by a right parenthesis @samp{)}; or a prefix | |
4068 | operator followed by an argument. | |
4069 | ||
4070 | @node Operators | |
4071 | @subsection Operators | |
4072 | ||
4073 | @cindex operators, in expressions | |
4074 | @cindex arithmetic functions | |
4075 | @cindex functions, in expressions | |
4076 | @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix | |
4077 | operators are followed by an argument. Infix operators appear | |
4078 | between their arguments. Operators may be preceded and/or followed by | |
4079 | whitespace. | |
4080 | ||
4081 | @node Prefix Ops | |
4082 | @subsection Prefix Operator | |
4083 | ||
4084 | @cindex prefix operators | |
4085 | @command{@value{AS}} has the following @dfn{prefix operators}. They each take | |
4086 | one argument, which must be absolute. | |
4087 | ||
4088 | @c the tex/end tex stuff surrounding this small table is meant to make | |
4089 | @c it align, on the printed page, with the similar table in the next | |
4090 | @c section (which is inside an enumerate). | |
4091 | @tex | |
4092 | \global\advance\leftskip by \itemindent | |
4093 | @end tex | |
4094 | ||
4095 | @table @code | |
4096 | @item - | |
4097 | @dfn{Negation}. Two's complement negation. | |
4098 | @item ~ | |
4099 | @dfn{Complementation}. Bitwise not. | |
4100 | @end table | |
4101 | ||
4102 | @tex | |
4103 | \global\advance\leftskip by -\itemindent | |
4104 | @end tex | |
4105 | ||
4106 | @node Infix Ops | |
4107 | @subsection Infix Operators | |
4108 | ||
4109 | @cindex infix operators | |
4110 | @cindex operators, permitted arguments | |
4111 | @dfn{Infix operators} take two arguments, one on either side. Operators | |
4112 | have precedence, but operations with equal precedence are performed left | |
4113 | to right. Apart from @code{+} or @option{-}, both arguments must be | |
4114 | absolute, and the result is absolute. | |
4115 | ||
4116 | @enumerate | |
4117 | @cindex operator precedence | |
4118 | @cindex precedence of operators | |
4119 | ||
4120 | @item | |
4121 | Highest Precedence | |
4122 | ||
4123 | @table @code | |
4124 | @item * | |
4125 | @dfn{Multiplication}. | |
4126 | ||
4127 | @item / | |
4128 | @dfn{Division}. Truncation is the same as the C operator @samp{/} | |
4129 | ||
4130 | @item % | |
4131 | @dfn{Remainder}. | |
4132 | ||
4133 | @item << | |
4134 | @dfn{Shift Left}. Same as the C operator @samp{<<}. | |
4135 | ||
4136 | @item >> | |
4137 | @dfn{Shift Right}. Same as the C operator @samp{>>}. | |
4138 | @end table | |
4139 | ||
4140 | @item | |
4141 | Intermediate precedence | |
4142 | ||
4143 | @table @code | |
4144 | @item | | |
4145 | ||
4146 | @dfn{Bitwise Inclusive Or}. | |
4147 | ||
4148 | @item & | |
4149 | @dfn{Bitwise And}. | |
4150 | ||
4151 | @item ^ | |
4152 | @dfn{Bitwise Exclusive Or}. | |
4153 | ||
4154 | @item ! | |
4155 | @dfn{Bitwise Or Not}. | |
4156 | @end table | |
4157 | ||
4158 | @item | |
4159 | Low Precedence | |
4160 | ||
4161 | @table @code | |
4162 | @cindex addition, permitted arguments | |
4163 | @cindex plus, permitted arguments | |
4164 | @cindex arguments for addition | |
4165 | @item + | |
4166 | @dfn{Addition}. If either argument is absolute, the result has the section of | |
4167 | the other argument. You may not add together arguments from different | |
4168 | sections. | |
4169 | ||
4170 | @cindex subtraction, permitted arguments | |
4171 | @cindex minus, permitted arguments | |
4172 | @cindex arguments for subtraction | |
4173 | @item - | |
4174 | @dfn{Subtraction}. If the right argument is absolute, the | |
4175 | result has the section of the left argument. | |
4176 | If both arguments are in the same section, the result is absolute. | |
4177 | You may not subtract arguments from different sections. | |
4178 | @c FIXME is there still something useful to say about undefined - undefined ? | |
4179 | ||
4180 | @cindex comparison expressions | |
4181 | @cindex expressions, comparison | |
4182 | @item == | |
4183 | @dfn{Is Equal To} | |
4184 | @item <> | |
4185 | @itemx != | |
4186 | @dfn{Is Not Equal To} | |
4187 | @item < | |
4188 | @dfn{Is Less Than} | |
4189 | @item > | |
4190 | @dfn{Is Greater Than} | |
4191 | @item >= | |
4192 | @dfn{Is Greater Than Or Equal To} | |
4193 | @item <= | |
4194 | @dfn{Is Less Than Or Equal To} | |
4195 | ||
4196 | The comparison operators can be used as infix operators. A true results has a | |
4197 | value of -1 whereas a false result has a value of 0. Note, these operators | |
4198 | perform signed comparisons. | |
4199 | @end table | |
4200 | ||
4201 | @item Lowest Precedence | |
4202 | ||
4203 | @table @code | |
4204 | @item && | |
4205 | @dfn{Logical And}. | |
4206 | ||
4207 | @item || | |
4208 | @dfn{Logical Or}. | |
4209 | ||
4210 | These two logical operations can be used to combine the results of sub | |
4211 | expressions. Note, unlike the comparison operators a true result returns a | |
4212 | value of 1 but a false results does still return 0. Also note that the logical | |
4213 | or operator has a slightly lower precedence than logical and. | |
4214 | ||
4215 | @end table | |
4216 | @end enumerate | |
4217 | ||
4218 | In short, it's only meaningful to add or subtract the @emph{offsets} in an | |
4219 | address; you can only have a defined section in one of the two arguments. | |
4220 | ||
4221 | @node Pseudo Ops | |
4222 | @chapter Assembler Directives | |
4223 | ||
4224 | @cindex directives, machine independent | |
4225 | @cindex pseudo-ops, machine independent | |
4226 | @cindex machine independent directives | |
4227 | All assembler directives have names that begin with a period (@samp{.}). | |
4228 | The names are case insensitive for most targets, and usually written | |
4229 | in lower case. | |
4230 | ||
4231 | This chapter discusses directives that are available regardless of the | |
4232 | target machine configuration for the @sc{gnu} assembler. | |
4233 | @ifset GENERIC | |
4234 | Some machine configurations provide additional directives. | |
4235 | @xref{Machine Dependencies}. | |
4236 | @end ifset | |
4237 | @ifclear GENERIC | |
4238 | @ifset machine-directives | |
4239 | @xref{Machine Dependencies}, for additional directives. | |
4240 | @end ifset | |
4241 | @end ifclear | |
4242 | ||
4243 | @menu | |
4244 | * Abort:: @code{.abort} | |
4245 | @ifset COFF | |
4246 | * ABORT (COFF):: @code{.ABORT} | |
4247 | @end ifset | |
4248 | ||
4249 | * Align:: @code{.align @var{abs-expr} , @var{abs-expr}} | |
4250 | * Altmacro:: @code{.altmacro} | |
4251 | * Ascii:: @code{.ascii "@var{string}"}@dots{} | |
4252 | * Asciz:: @code{.asciz "@var{string}"}@dots{} | |
4253 | * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}} | |
4254 | * Bundle directives:: @code{.bundle_align_mode @var{abs-expr}}, etc | |
4255 | * Byte:: @code{.byte @var{expressions}} | |
4256 | * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc. | |
4257 | * Comm:: @code{.comm @var{symbol} , @var{length} } | |
4258 | * Data:: @code{.data @var{subsection}} | |
4259 | * Dc:: @code{.dc[@var{size}] @var{expressions}} | |
4260 | * Dcb:: @code{.dcb[@var{size}] @var{number} [,@var{fill}]} | |
4261 | * Ds:: @code{.ds[@var{size}] @var{number} [,@var{fill}]} | |
4262 | @ifset COFF | |
4263 | * Def:: @code{.def @var{name}} | |
4264 | @end ifset | |
4265 | @ifset aout | |
4266 | * Desc:: @code{.desc @var{symbol}, @var{abs-expression}} | |
4267 | @end ifset | |
4268 | @ifset COFF | |
4269 | * Dim:: @code{.dim} | |
4270 | @end ifset | |
4271 | ||
4272 | * Double:: @code{.double @var{flonums}} | |
4273 | * Eject:: @code{.eject} | |
4274 | * Else:: @code{.else} | |
4275 | * Elseif:: @code{.elseif} | |
4276 | * End:: @code{.end} | |
4277 | @ifset COFF | |
4278 | * Endef:: @code{.endef} | |
4279 | @end ifset | |
4280 | ||
4281 | * Endfunc:: @code{.endfunc} | |
4282 | * Endif:: @code{.endif} | |
4283 | * Equ:: @code{.equ @var{symbol}, @var{expression}} | |
4284 | * Equiv:: @code{.equiv @var{symbol}, @var{expression}} | |
4285 | * Eqv:: @code{.eqv @var{symbol}, @var{expression}} | |
4286 | * Err:: @code{.err} | |
4287 | * Error:: @code{.error @var{string}} | |
4288 | * Exitm:: @code{.exitm} | |
4289 | * Extern:: @code{.extern} | |
4290 | * Fail:: @code{.fail} | |
4291 | * File:: @code{.file} | |
4292 | * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}} | |
4293 | * Float:: @code{.float @var{flonums}} | |
4294 | * Func:: @code{.func} | |
4295 | * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}} | |
4296 | @ifset ELF | |
4297 | * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}} | |
4298 | * Hidden:: @code{.hidden @var{names}} | |
4299 | @end ifset | |
4300 | ||
4301 | * hword:: @code{.hword @var{expressions}} | |
4302 | * Ident:: @code{.ident} | |
4303 | * If:: @code{.if @var{absolute expression}} | |
4304 | * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]} | |
4305 | * Include:: @code{.include "@var{file}"} | |
4306 | * Int:: @code{.int @var{expressions}} | |
4307 | @ifset ELF | |
4308 | * Internal:: @code{.internal @var{names}} | |
4309 | @end ifset | |
4310 | ||
4311 | * Irp:: @code{.irp @var{symbol},@var{values}}@dots{} | |
4312 | * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{} | |
4313 | * Lcomm:: @code{.lcomm @var{symbol} , @var{length}} | |
4314 | * Lflags:: @code{.lflags} | |
4315 | @ifclear no-line-dir | |
4316 | * Line:: @code{.line @var{line-number}} | |
4317 | @end ifclear | |
4318 | ||
4319 | * Linkonce:: @code{.linkonce [@var{type}]} | |
4320 | * List:: @code{.list} | |
4321 | * Ln:: @code{.ln @var{line-number}} | |
4322 | * Loc:: @code{.loc @var{fileno} @var{lineno}} | |
4323 | * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}} | |
4324 | @ifset ELF | |
4325 | * Local:: @code{.local @var{names}} | |
4326 | @end ifset | |
4327 | ||
4328 | * Long:: @code{.long @var{expressions}} | |
4329 | @ignore | |
4330 | * Lsym:: @code{.lsym @var{symbol}, @var{expression}} | |
4331 | @end ignore | |
4332 | ||
4333 | * Macro:: @code{.macro @var{name} @var{args}}@dots{} | |
4334 | * MRI:: @code{.mri @var{val}} | |
4335 | * Noaltmacro:: @code{.noaltmacro} | |
4336 | * Nolist:: @code{.nolist} | |
4337 | * Nops:: @code{.nops @var{size}[, @var{control}]} | |
4338 | * Octa:: @code{.octa @var{bignums}} | |
4339 | * Offset:: @code{.offset @var{loc}} | |
4340 | * Org:: @code{.org @var{new-lc}, @var{fill}} | |
4341 | * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} | |
4342 | @ifset ELF | |
4343 | * PopSection:: @code{.popsection} | |
4344 | * Previous:: @code{.previous} | |
4345 | @end ifset | |
4346 | ||
4347 | * Print:: @code{.print @var{string}} | |
4348 | @ifset ELF | |
4349 | * Protected:: @code{.protected @var{names}} | |
4350 | @end ifset | |
4351 | ||
4352 | * Psize:: @code{.psize @var{lines}, @var{columns}} | |
4353 | * Purgem:: @code{.purgem @var{name}} | |
4354 | @ifset ELF | |
4355 | * PushSection:: @code{.pushsection @var{name}} | |
4356 | @end ifset | |
4357 | ||
4358 | * Quad:: @code{.quad @var{bignums}} | |
4359 | * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]} | |
4360 | * Rept:: @code{.rept @var{count}} | |
4361 | * Sbttl:: @code{.sbttl "@var{subheading}"} | |
4362 | @ifset COFF | |
4363 | * Scl:: @code{.scl @var{class}} | |
4364 | @end ifset | |
4365 | @ifset COFF-ELF | |
4366 | * Section:: @code{.section @var{name}[, @var{flags}]} | |
4367 | @end ifset | |
4368 | ||
4369 | * Set:: @code{.set @var{symbol}, @var{expression}} | |
4370 | * Short:: @code{.short @var{expressions}} | |
4371 | * Single:: @code{.single @var{flonums}} | |
4372 | @ifset COFF-ELF | |
4373 | * Size:: @code{.size [@var{name} , @var{expression}]} | |
4374 | @end ifset | |
4375 | @ifclear no-space-dir | |
4376 | * Skip:: @code{.skip @var{size} [,@var{fill}]} | |
4377 | @end ifclear | |
4378 | ||
4379 | * Sleb128:: @code{.sleb128 @var{expressions}} | |
4380 | @ifclear no-space-dir | |
4381 | * Space:: @code{.space @var{size} [,@var{fill}]} | |
4382 | @end ifclear | |
4383 | @ifset have-stabs | |
4384 | * Stab:: @code{.stabd, .stabn, .stabs} | |
4385 | @end ifset | |
4386 | ||
4387 | * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"} | |
4388 | * Struct:: @code{.struct @var{expression}} | |
4389 | @ifset ELF | |
4390 | * SubSection:: @code{.subsection} | |
4391 | * Symver:: @code{.symver @var{name},@var{name2@@nodename}} | |
4392 | @end ifset | |
4393 | ||
4394 | @ifset COFF | |
4395 | * Tag:: @code{.tag @var{structname}} | |
4396 | @end ifset | |
4397 | ||
4398 | * Text:: @code{.text @var{subsection}} | |
4399 | * Title:: @code{.title "@var{heading}"} | |
4400 | @ifset COFF-ELF | |
4401 | * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>} | |
4402 | @end ifset | |
4403 | ||
4404 | * Uleb128:: @code{.uleb128 @var{expressions}} | |
4405 | @ifset COFF | |
4406 | * Val:: @code{.val @var{addr}} | |
4407 | @end ifset | |
4408 | ||
4409 | @ifset ELF | |
4410 | * Version:: @code{.version "@var{string}"} | |
4411 | * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}} | |
4412 | * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}} | |
4413 | @end ifset | |
4414 | ||
4415 | * Warning:: @code{.warning @var{string}} | |
4416 | * Weak:: @code{.weak @var{names}} | |
4417 | * Weakref:: @code{.weakref @var{alias}, @var{symbol}} | |
4418 | * Word:: @code{.word @var{expressions}} | |
4419 | @ifclear no-space-dir | |
4420 | * Zero:: @code{.zero @var{size}} | |
4421 | @end ifclear | |
4422 | @ifset ELF | |
4423 | * 2byte:: @code{.2byte @var{expressions}} | |
4424 | * 4byte:: @code{.4byte @var{expressions}} | |
4425 | * 8byte:: @code{.8byte @var{bignums}} | |
4426 | @end ifset | |
4427 | * Deprecated:: Deprecated Directives | |
4428 | @end menu | |
4429 | ||
4430 | @node Abort | |
4431 | @section @code{.abort} | |
4432 | ||
4433 | @cindex @code{abort} directive | |
4434 | @cindex stopping the assembly | |
4435 | This directive stops the assembly immediately. It is for | |
4436 | compatibility with other assemblers. The original idea was that the | |
4437 | assembly language source would be piped into the assembler. If the sender | |
4438 | of the source quit, it could use this directive tells @command{@value{AS}} to | |
4439 | quit also. One day @code{.abort} will not be supported. | |
4440 | ||
4441 | @ifset COFF | |
4442 | @node ABORT (COFF) | |
4443 | @section @code{.ABORT} (COFF) | |
4444 | ||
4445 | @cindex @code{ABORT} directive | |
4446 | When producing COFF output, @command{@value{AS}} accepts this directive as a | |
4447 | synonym for @samp{.abort}. | |
4448 | ||
4449 | @end ifset | |
4450 | ||
4451 | @node Align | |
4452 | @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} | |
4453 | ||
4454 | @cindex padding the location counter | |
4455 | @cindex @code{align} directive | |
4456 | Pad the location counter (in the current subsection) to a particular storage | |
4457 | boundary. The first expression (which must be absolute) is the alignment | |
4458 | required, as described below. | |
4459 | ||
4460 | The second expression (also absolute) gives the fill value to be stored in the | |
4461 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
4462 | padding bytes are normally zero. However, on most systems, if the section is | |
4463 | marked as containing code and the fill value is omitted, the space is filled | |
4464 | with no-op instructions. | |
4465 | ||
4466 | The third expression is also absolute, and is also optional. If it is present, | |
4467 | it is the maximum number of bytes that should be skipped by this alignment | |
4468 | directive. If doing the alignment would require skipping more bytes than the | |
4469 | specified maximum, then the alignment is not done at all. You can omit the | |
4470 | fill value (the second argument) entirely by simply using two commas after the | |
4471 | required alignment; this can be useful if you want the alignment to be filled | |
4472 | with no-op instructions when appropriate. | |
4473 | ||
4474 | The way the required alignment is specified varies from system to system. | |
4475 | For the arc, hppa, i386 using ELF, iq2000, m68k, or1k, | |
4476 | s390, sparc, tic4x, tic80 and xtensa, the first expression is the | |
4477 | alignment request in bytes. For example @samp{.align 8} advances | |
4478 | the location counter until it is a multiple of 8. If the location counter | |
4479 | is already a multiple of 8, no change is needed. For the tic54x, the | |
4480 | first expression is the alignment request in words. | |
4481 | ||
4482 | For other systems, including ppc, i386 using a.out format, arm and | |
4483 | strongarm, it is the | |
4484 | number of low-order zero bits the location counter must have after | |
4485 | advancement. For example @samp{.align 3} advances the location | |
4486 | counter until it a multiple of 8. If the location counter is already a | |
4487 | multiple of 8, no change is needed. | |
4488 | ||
4489 | This inconsistency is due to the different behaviors of the various | |
4490 | native assemblers for these systems which GAS must emulate. | |
4491 | GAS also provides @code{.balign} and @code{.p2align} directives, | |
4492 | described later, which have a consistent behavior across all | |
4493 | architectures (but are specific to GAS). | |
4494 | ||
4495 | @node Altmacro | |
4496 | @section @code{.altmacro} | |
4497 | Enable alternate macro mode, enabling: | |
4498 | ||
4499 | @ftable @code | |
4500 | @item LOCAL @var{name} [ , @dots{} ] | |
4501 | One additional directive, @code{LOCAL}, is available. It is used to | |
4502 | generate a string replacement for each of the @var{name} arguments, and | |
4503 | replace any instances of @var{name} in each macro expansion. The | |
4504 | replacement string is unique in the assembly, and different for each | |
4505 | separate macro expansion. @code{LOCAL} allows you to write macros that | |
4506 | define symbols, without fear of conflict between separate macro expansions. | |
4507 | ||
4508 | @item String delimiters | |
4509 | You can write strings delimited in these other ways besides | |
4510 | @code{"@var{string}"}: | |
4511 | ||
4512 | @table @code | |
4513 | @item '@var{string}' | |
4514 | You can delimit strings with single-quote characters. | |
4515 | ||
4516 | @item <@var{string}> | |
4517 | You can delimit strings with matching angle brackets. | |
4518 | @end table | |
4519 | ||
4520 | @item single-character string escape | |
4521 | To include any single character literally in a string (even if the | |
4522 | character would otherwise have some special meaning), you can prefix the | |
4523 | character with @samp{!} (an exclamation mark). For example, you can | |
4524 | write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}. | |
4525 | ||
4526 | @item Expression results as strings | |
4527 | You can write @samp{%@var{expr}} to evaluate the expression @var{expr} | |
4528 | and use the result as a string. | |
4529 | @end ftable | |
4530 | ||
4531 | @node Ascii | |
4532 | @section @code{.ascii "@var{string}"}@dots{} | |
4533 | ||
4534 | @cindex @code{ascii} directive | |
4535 | @cindex string literals | |
4536 | @code{.ascii} expects zero or more string literals (@pxref{Strings}) | |
4537 | separated by commas. It assembles each string (with no automatic | |
4538 | trailing zero byte) into consecutive addresses. | |
4539 | ||
4540 | @node Asciz | |
4541 | @section @code{.asciz "@var{string}"}@dots{} | |
4542 | ||
4543 | @cindex @code{asciz} directive | |
4544 | @cindex zero-terminated strings | |
4545 | @cindex null-terminated strings | |
4546 | @code{.asciz} is just like @code{.ascii}, but each string is followed by | |
4547 | a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''. | |
4548 | ||
4549 | @node Balign | |
4550 | @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} | |
4551 | ||
4552 | @cindex padding the location counter given number of bytes | |
4553 | @cindex @code{balign} directive | |
4554 | Pad the location counter (in the current subsection) to a particular | |
4555 | storage boundary. The first expression (which must be absolute) is the | |
4556 | alignment request in bytes. For example @samp{.balign 8} advances | |
4557 | the location counter until it is a multiple of 8. If the location counter | |
4558 | is already a multiple of 8, no change is needed. | |
4559 | ||
4560 | The second expression (also absolute) gives the fill value to be stored in the | |
4561 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
4562 | padding bytes are normally zero. However, on most systems, if the section is | |
4563 | marked as containing code and the fill value is omitted, the space is filled | |
4564 | with no-op instructions. | |
4565 | ||
4566 | The third expression is also absolute, and is also optional. If it is present, | |
4567 | it is the maximum number of bytes that should be skipped by this alignment | |
4568 | directive. If doing the alignment would require skipping more bytes than the | |
4569 | specified maximum, then the alignment is not done at all. You can omit the | |
4570 | fill value (the second argument) entirely by simply using two commas after the | |
4571 | required alignment; this can be useful if you want the alignment to be filled | |
4572 | with no-op instructions when appropriate. | |
4573 | ||
4574 | @cindex @code{balignw} directive | |
4575 | @cindex @code{balignl} directive | |
4576 | The @code{.balignw} and @code{.balignl} directives are variants of the | |
4577 | @code{.balign} directive. The @code{.balignw} directive treats the fill | |
4578 | pattern as a two byte word value. The @code{.balignl} directives treats the | |
4579 | fill pattern as a four byte longword value. For example, @code{.balignw | |
4580 | 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be | |
4581 | filled in with the value 0x368d (the exact placement of the bytes depends upon | |
4582 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is | |
4583 | undefined. | |
4584 | ||
4585 | @node Bundle directives | |
4586 | @section Bundle directives | |
4587 | @subsection @code{.bundle_align_mode @var{abs-expr}} | |
4588 | @cindex @code{bundle_align_mode} directive | |
4589 | @cindex bundle | |
4590 | @cindex instruction bundle | |
4591 | @cindex aligned instruction bundle | |
4592 | @code{.bundle_align_mode} enables or disables @dfn{aligned instruction | |
4593 | bundle} mode. In this mode, sequences of adjacent instructions are grouped | |
4594 | into fixed-sized @dfn{bundles}. If the argument is zero, this mode is | |
4595 | disabled (which is the default state). If the argument it not zero, it | |
4596 | gives the size of an instruction bundle as a power of two (as for the | |
4597 | @code{.p2align} directive, @pxref{P2align}). | |
4598 | ||
4599 | For some targets, it's an ABI requirement that no instruction may span a | |
4600 | certain aligned boundary. A @dfn{bundle} is simply a sequence of | |
4601 | instructions that starts on an aligned boundary. For example, if | |
4602 | @var{abs-expr} is @code{5} then the bundle size is 32, so each aligned | |
4603 | chunk of 32 bytes is a bundle. When aligned instruction bundle mode is in | |
4604 | effect, no single instruction may span a boundary between bundles. If an | |
4605 | instruction would start too close to the end of a bundle for the length of | |
4606 | that particular instruction to fit within the bundle, then the space at the | |
4607 | end of that bundle is filled with no-op instructions so the instruction | |
4608 | starts in the next bundle. As a corollary, it's an error if any single | |
4609 | instruction's encoding is longer than the bundle size. | |
4610 | ||
4611 | @subsection @code{.bundle_lock} and @code{.bundle_unlock} | |
4612 | @cindex @code{bundle_lock} directive | |
4613 | @cindex @code{bundle_unlock} directive | |
4614 | The @code{.bundle_lock} and directive @code{.bundle_unlock} directives | |
4615 | allow explicit control over instruction bundle padding. These directives | |
4616 | are only valid when @code{.bundle_align_mode} has been used to enable | |
4617 | aligned instruction bundle mode. It's an error if they appear when | |
4618 | @code{.bundle_align_mode} has not been used at all, or when the last | |
4619 | directive was @w{@code{.bundle_align_mode 0}}. | |
4620 | ||
4621 | @cindex bundle-locked | |
4622 | For some targets, it's an ABI requirement that certain instructions may | |
4623 | appear only as part of specified permissible sequences of multiple | |
4624 | instructions, all within the same bundle. A pair of @code{.bundle_lock} | |
4625 | and @code{.bundle_unlock} directives define a @dfn{bundle-locked} | |
4626 | instruction sequence. For purposes of aligned instruction bundle mode, a | |
4627 | sequence starting with @code{.bundle_lock} and ending with | |
4628 | @code{.bundle_unlock} is treated as a single instruction. That is, the | |
4629 | entire sequence must fit into a single bundle and may not span a bundle | |
4630 | boundary. If necessary, no-op instructions will be inserted before the | |
4631 | first instruction of the sequence so that the whole sequence starts on an | |
4632 | aligned bundle boundary. It's an error if the sequence is longer than the | |
4633 | bundle size. | |
4634 | ||
4635 | For convenience when using @code{.bundle_lock} and @code{.bundle_unlock} | |
4636 | inside assembler macros (@pxref{Macro}), bundle-locked sequences may be | |
4637 | nested. That is, a second @code{.bundle_lock} directive before the next | |
4638 | @code{.bundle_unlock} directive has no effect except that it must be | |
4639 | matched by another closing @code{.bundle_unlock} so that there is the | |
4640 | same number of @code{.bundle_lock} and @code{.bundle_unlock} directives. | |
4641 | ||
4642 | @node Byte | |
4643 | @section @code{.byte @var{expressions}} | |
4644 | ||
4645 | @cindex @code{byte} directive | |
4646 | @cindex integers, one byte | |
4647 | @code{.byte} expects zero or more expressions, separated by commas. | |
4648 | Each expression is assembled into the next byte. | |
4649 | ||
4650 | @node CFI directives | |
4651 | @section CFI directives | |
4652 | @subsection @code{.cfi_sections @var{section_list}} | |
4653 | @cindex @code{cfi_sections} directive | |
4654 | @code{.cfi_sections} may be used to specify whether CFI directives | |
4655 | should emit @code{.eh_frame} section and/or @code{.debug_frame} section. | |
4656 | If @var{section_list} is @code{.eh_frame}, @code{.eh_frame} is emitted, | |
4657 | if @var{section_list} is @code{.debug_frame}, @code{.debug_frame} is emitted. | |
4658 | To emit both use @code{.eh_frame, .debug_frame}. The default if this | |
4659 | directive is not used is @code{.cfi_sections .eh_frame}. | |
4660 | ||
4661 | On targets that support compact unwinding tables these can be generated | |
4662 | by specifying @code{.eh_frame_entry} instead of @code{.eh_frame}. | |
4663 | ||
4664 | Some targets may support an additional name, such as @code{.c6xabi.exidx} | |
4665 | which is used by the @value{TIC6X} target. | |
4666 | ||
4667 | The @code{.cfi_sections} directive can be repeated, with the same or different | |
4668 | arguments, provided that CFI generation has not yet started. Once CFI | |
4669 | generation has started however the section list is fixed and any attempts to | |
4670 | redefine it will result in an error. | |
4671 | ||
4672 | @subsection @code{.cfi_startproc [simple]} | |
4673 | @cindex @code{cfi_startproc} directive | |
4674 | @code{.cfi_startproc} is used at the beginning of each function that | |
4675 | should have an entry in @code{.eh_frame}. It initializes some internal | |
4676 | data structures. Don't forget to close the function by | |
4677 | @code{.cfi_endproc}. | |
4678 | ||
4679 | Unless @code{.cfi_startproc} is used along with parameter @code{simple} | |
4680 | it also emits some architecture dependent initial CFI instructions. | |
4681 | ||
4682 | @subsection @code{.cfi_endproc} | |
4683 | @cindex @code{cfi_endproc} directive | |
4684 | @code{.cfi_endproc} is used at the end of a function where it closes its | |
4685 | unwind entry previously opened by | |
4686 | @code{.cfi_startproc}, and emits it to @code{.eh_frame}. | |
4687 | ||
4688 | @subsection @code{.cfi_personality @var{encoding} [, @var{exp}]} | |
4689 | @cindex @code{cfi_personality} directive | |
4690 | @code{.cfi_personality} defines personality routine and its encoding. | |
4691 | @var{encoding} must be a constant determining how the personality | |
4692 | should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second | |
4693 | argument is not present, otherwise second argument should be | |
4694 | a constant or a symbol name. When using indirect encodings, | |
4695 | the symbol provided should be the location where personality | |
4696 | can be loaded from, not the personality routine itself. | |
4697 | The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff}, | |
4698 | no personality routine. | |
4699 | ||
4700 | @subsection @code{.cfi_personality_id @var{id}} | |
4701 | @cindex @code{cfi_personality_id} directive | |
4702 | @code{cfi_personality_id} defines a personality routine by its index as | |
4703 | defined in a compact unwinding format. | |
4704 | Only valid when generating compact EH frames (i.e. | |
4705 | with @code{.cfi_sections eh_frame_entry}. | |
4706 | ||
4707 | @subsection @code{.cfi_fde_data [@var{opcode1} [, @dots{}]]} | |
4708 | @cindex @code{cfi_fde_data} directive | |
4709 | @code{cfi_fde_data} is used to describe the compact unwind opcodes to be | |
4710 | used for the current function. These are emitted inline in the | |
4711 | @code{.eh_frame_entry} section if small enough and there is no LSDA, or | |
4712 | in the @code{.gnu.extab} section otherwise. | |
4713 | Only valid when generating compact EH frames (i.e. | |
4714 | with @code{.cfi_sections eh_frame_entry}. | |
4715 | ||
4716 | @subsection @code{.cfi_lsda @var{encoding} [, @var{exp}]} | |
4717 | @code{.cfi_lsda} defines LSDA and its encoding. | |
4718 | @var{encoding} must be a constant determining how the LSDA | |
4719 | should be encoded. If it is 255 (@code{DW_EH_PE_omit}), the second | |
4720 | argument is not present, otherwise the second argument should be a constant | |
4721 | or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff}, | |
4722 | meaning that no LSDA is present. | |
4723 | ||
4724 | @subsection @code{.cfi_inline_lsda} [@var{align}] | |
4725 | @code{.cfi_inline_lsda} marks the start of a LSDA data section and | |
4726 | switches to the corresponding @code{.gnu.extab} section. | |
4727 | Must be preceded by a CFI block containing a @code{.cfi_lsda} directive. | |
4728 | Only valid when generating compact EH frames (i.e. | |
4729 | with @code{.cfi_sections eh_frame_entry}. | |
4730 | ||
4731 | The table header and unwinding opcodes will be generated at this point, | |
4732 | so that they are immediately followed by the LSDA data. The symbol | |
4733 | referenced by the @code{.cfi_lsda} directive should still be defined | |
4734 | in case a fallback FDE based encoding is used. The LSDA data is terminated | |
4735 | by a section directive. | |
4736 | ||
4737 | The optional @var{align} argument specifies the alignment required. | |
4738 | The alignment is specified as a power of two, as with the | |
4739 | @code{.p2align} directive. | |
4740 | ||
4741 | @subsection @code{.cfi_def_cfa @var{register}, @var{offset}} | |
4742 | @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take | |
4743 | address from @var{register} and add @var{offset} to it}. | |
4744 | ||
4745 | @subsection @code{.cfi_def_cfa_register @var{register}} | |
4746 | @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From | |
4747 | now on @var{register} will be used instead of the old one. Offset | |
4748 | remains the same. | |
4749 | ||
4750 | @subsection @code{.cfi_def_cfa_offset @var{offset}} | |
4751 | @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register | |
4752 | remains the same, but @var{offset} is new. Note that it is the | |
4753 | absolute offset that will be added to a defined register to compute | |
4754 | CFA address. | |
4755 | ||
4756 | @subsection @code{.cfi_adjust_cfa_offset @var{offset}} | |
4757 | Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative | |
4758 | value that is added/subtracted from the previous offset. | |
4759 | ||
4760 | @subsection @code{.cfi_offset @var{register}, @var{offset}} | |
4761 | Previous value of @var{register} is saved at offset @var{offset} from | |
4762 | CFA. | |
4763 | ||
4764 | @subsection @code{.cfi_val_offset @var{register}, @var{offset}} | |
4765 | Previous value of @var{register} is CFA + @var{offset}. | |
4766 | ||
4767 | @subsection @code{.cfi_rel_offset @var{register}, @var{offset}} | |
4768 | Previous value of @var{register} is saved at offset @var{offset} from | |
4769 | the current CFA register. This is transformed to @code{.cfi_offset} | |
4770 | using the known displacement of the CFA register from the CFA. | |
4771 | This is often easier to use, because the number will match the | |
4772 | code it's annotating. | |
4773 | ||
4774 | @subsection @code{.cfi_register @var{register1}, @var{register2}} | |
4775 | Previous value of @var{register1} is saved in register @var{register2}. | |
4776 | ||
4777 | @subsection @code{.cfi_restore @var{register}} | |
4778 | @code{.cfi_restore} says that the rule for @var{register} is now the | |
4779 | same as it was at the beginning of the function, after all initial | |
4780 | instruction added by @code{.cfi_startproc} were executed. | |
4781 | ||
4782 | @subsection @code{.cfi_undefined @var{register}} | |
4783 | From now on the previous value of @var{register} can't be restored anymore. | |
4784 | ||
4785 | @subsection @code{.cfi_same_value @var{register}} | |
4786 | Current value of @var{register} is the same like in the previous frame, | |
4787 | i.e. no restoration needed. | |
4788 | ||
4789 | @subsection @code{.cfi_remember_state} and @code{.cfi_restore_state} | |
4790 | @code{.cfi_remember_state} pushes the set of rules for every register onto an | |
4791 | implicit stack, while @code{.cfi_restore_state} pops them off the stack and | |
4792 | places them in the current row. This is useful for situations where you have | |
4793 | multiple @code{.cfi_*} directives that need to be undone due to the control | |
4794 | flow of the program. For example, we could have something like this (assuming | |
4795 | the CFA is the value of @code{rbp}): | |
4796 | ||
4797 | @smallexample | |
4798 | je label | |
4799 | popq %rbx | |
4800 | .cfi_restore %rbx | |
4801 | popq %r12 | |
4802 | .cfi_restore %r12 | |
4803 | popq %rbp | |
4804 | .cfi_restore %rbp | |
4805 | .cfi_def_cfa %rsp, 8 | |
4806 | ret | |
4807 | label: | |
4808 | /* Do something else */ | |
4809 | @end smallexample | |
4810 | ||
4811 | Here, we want the @code{.cfi} directives to affect only the rows corresponding | |
4812 | to the instructions before @code{label}. This means we'd have to add multiple | |
4813 | @code{.cfi} directives after @code{label} to recreate the original save | |
4814 | locations of the registers, as well as setting the CFA back to the value of | |
4815 | @code{rbp}. This would be clumsy, and result in a larger binary size. Instead, | |
4816 | we can write: | |
4817 | ||
4818 | @smallexample | |
4819 | je label | |
4820 | popq %rbx | |
4821 | .cfi_remember_state | |
4822 | .cfi_restore %rbx | |
4823 | popq %r12 | |
4824 | .cfi_restore %r12 | |
4825 | popq %rbp | |
4826 | .cfi_restore %rbp | |
4827 | .cfi_def_cfa %rsp, 8 | |
4828 | ret | |
4829 | label: | |
4830 | .cfi_restore_state | |
4831 | /* Do something else */ | |
4832 | @end smallexample | |
4833 | ||
4834 | That way, the rules for the instructions after @code{label} will be the same | |
4835 | as before the first @code{.cfi_restore} without having to use multiple | |
4836 | @code{.cfi} directives. | |
4837 | ||
4838 | @subsection @code{.cfi_return_column @var{register}} | |
4839 | Change return column @var{register}, i.e. the return address is either | |
4840 | directly in @var{register} or can be accessed by rules for @var{register}. | |
4841 | ||
4842 | @subsection @code{.cfi_signal_frame} | |
4843 | Mark current function as signal trampoline. | |
4844 | ||
4845 | @subsection @code{.cfi_window_save} | |
4846 | SPARC register window has been saved. | |
4847 | ||
4848 | @subsection @code{.cfi_escape} @var{expression}[, @dots{}] | |
4849 | Allows the user to add arbitrary bytes to the unwind info. One | |
4850 | might use this to add OS-specific CFI opcodes, or generic CFI | |
4851 | opcodes that GAS does not yet support. | |
4852 | ||
4853 | @subsection @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}} | |
4854 | The current value of @var{register} is @var{label}. The value of @var{label} | |
4855 | will be encoded in the output file according to @var{encoding}; see the | |
4856 | description of @code{.cfi_personality} for details on this encoding. | |
4857 | ||
4858 | The usefulness of equating a register to a fixed label is probably | |
4859 | limited to the return address register. Here, it can be useful to | |
4860 | mark a code segment that has only one return address which is reached | |
4861 | by a direct branch and no copy of the return address exists in memory | |
4862 | or another register. | |
4863 | ||
4864 | @node Comm | |
4865 | @section @code{.comm @var{symbol} , @var{length} } | |
4866 | ||
4867 | @cindex @code{comm} directive | |
4868 | @cindex symbol, common | |
4869 | @code{.comm} declares a common symbol named @var{symbol}. When linking, a | |
4870 | common symbol in one object file may be merged with a defined or common symbol | |
4871 | of the same name in another object file. If @code{@value{LD}} does not see a | |
4872 | definition for the symbol--just one or more common symbols--then it will | |
4873 | allocate @var{length} bytes of uninitialized memory. @var{length} must be an | |
4874 | absolute expression. If @code{@value{LD}} sees multiple common symbols with | |
4875 | the same name, and they do not all have the same size, it will allocate space | |
4876 | using the largest size. | |
4877 | ||
4878 | @ifset COFF-ELF | |
4879 | When using ELF or (as a GNU extension) PE, the @code{.comm} directive takes | |
4880 | an optional third argument. This is the desired alignment of the symbol, | |
4881 | specified for ELF as a byte boundary (for example, an alignment of 16 means | |
4882 | that the least significant 4 bits of the address should be zero), and for PE | |
4883 | as a power of two (for example, an alignment of 5 means aligned to a 32-byte | |
4884 | boundary). The alignment must be an absolute expression, and it must be a | |
4885 | power of two. If @code{@value{LD}} allocates uninitialized memory for the | |
4886 | common symbol, it will use the alignment when placing the symbol. If no | |
4887 | alignment is specified, @command{@value{AS}} will set the alignment to the | |
4888 | largest power of two less than or equal to the size of the symbol, up to a | |
4889 | maximum of 16 on ELF, or the default section alignment of 4 on PE@footnote{This | |
4890 | is not the same as the executable image file alignment controlled by @code{@value{LD}}'s | |
4891 | @samp{--section-alignment} option; image file sections in PE are aligned to | |
4892 | multiples of 4096, which is far too large an alignment for ordinary variables. | |
4893 | It is rather the default alignment for (non-debug) sections within object | |
4894 | (@samp{*.o}) files, which are less strictly aligned.}. | |
4895 | @end ifset | |
4896 | ||
4897 | @ifset HPPA | |
4898 | The syntax for @code{.comm} differs slightly on the HPPA. The syntax is | |
4899 | @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional. | |
4900 | @end ifset | |
4901 | ||
4902 | @node Data | |
4903 | @section @code{.data @var{subsection}} | |
4904 | @cindex @code{data} directive | |
4905 | ||
4906 | @code{.data} tells @command{@value{AS}} to assemble the following statements onto the | |
4907 | end of the data subsection numbered @var{subsection} (which is an | |
4908 | absolute expression). If @var{subsection} is omitted, it defaults | |
4909 | to zero. | |
4910 | ||
4911 | @node Dc | |
4912 | @section @code{.dc[@var{size}] @var{expressions}} | |
4913 | @cindex @code{dc} directive | |
4914 | ||
4915 | The @code{.dc} directive expects zero or more @var{expressions} separated by | |
4916 | commas. These expressions are evaluated and their values inserted into the | |
4917 | current section. The size of the emitted value depends upon the suffix to the | |
4918 | @code{.dc} directive: | |
4919 | ||
4920 | @table @code | |
4921 | @item @samp{.a} | |
4922 | Emits N-bit values, where N is the size of an address on the target system. | |
4923 | @item @samp{.b} | |
4924 | Emits 8-bit values. | |
4925 | @item @samp{.d} | |
4926 | Emits double precision floating-point values. | |
4927 | @item @samp{.l} | |
4928 | Emits 32-bit values. | |
4929 | @item @samp{.s} | |
4930 | Emits single precision floating-point values. | |
4931 | @item @samp{.w} | |
4932 | Emits 16-bit values. | |
4933 | Note - this is true even on targets where the @code{.word} directive would emit | |
4934 | 32-bit values. | |
4935 | @item @samp{.x} | |
4936 | Emits long double precision floating-point values. | |
4937 | @end table | |
4938 | ||
4939 | If no suffix is used then @samp{.w} is assumed. | |
4940 | ||
4941 | The byte ordering is target dependent, as is the size and format of floating | |
4942 | point values. | |
4943 | ||
4944 | @node Dcb | |
4945 | @section @code{.dcb[@var{size}] @var{number} [,@var{fill}]} | |
4946 | @cindex @code{dcb} directive | |
4947 | This directive emits @var{number} copies of @var{fill}, each of @var{size} | |
4948 | bytes. Both @var{number} and @var{fill} are absolute expressions. If the | |
4949 | comma and @var{fill} are omitted, @var{fill} is assumed to be zero. The | |
4950 | @var{size} suffix, if present, must be one of: | |
4951 | ||
4952 | @table @code | |
4953 | @item @samp{.b} | |
4954 | Emits single byte values. | |
4955 | @item @samp{.d} | |
4956 | Emits double-precision floating point values. | |
4957 | @item @samp{.l} | |
4958 | Emits 4-byte values. | |
4959 | @item @samp{.s} | |
4960 | Emits single-precision floating point values. | |
4961 | @item @samp{.w} | |
4962 | Emits 2-byte values. | |
4963 | @item @samp{.x} | |
4964 | Emits long double-precision floating point values. | |
4965 | @end table | |
4966 | ||
4967 | If the @var{size} suffix is omitted then @samp{.w} is assumed. | |
4968 | ||
4969 | The byte ordering is target dependent, as is the size and format of floating | |
4970 | point values. | |
4971 | ||
4972 | @node Ds | |
4973 | @section @code{.ds[@var{size}] @var{number} [,@var{fill}]} | |
4974 | @cindex @code{ds} directive | |
4975 | This directive emits @var{number} copies of @var{fill}, each of @var{size} | |
4976 | bytes. Both @var{number} and @var{fill} are absolute expressions. If the | |
4977 | comma and @var{fill} are omitted, @var{fill} is assumed to be zero. The | |
4978 | @var{size} suffix, if present, must be one of: | |
4979 | ||
4980 | @table @code | |
4981 | @item @samp{.b} | |
4982 | Emits single byte values. | |
4983 | @item @samp{.d} | |
4984 | Emits 8-byte values. | |
4985 | @item @samp{.l} | |
4986 | Emits 4-byte values. | |
4987 | @item @samp{.p} | |
4988 | Emits 12-byte values. | |
4989 | @item @samp{.s} | |
4990 | Emits 4-byte values. | |
4991 | @item @samp{.w} | |
4992 | Emits 2-byte values. | |
4993 | @item @samp{.x} | |
4994 | Emits 12-byte values. | |
4995 | @end table | |
4996 | ||
4997 | Note - unlike the @code{.dcb} directive the @samp{.d}, @samp{.s} and @samp{.x} | |
4998 | suffixes do not indicate that floating-point values are to be inserted. | |
4999 | ||
5000 | If the @var{size} suffix is omitted then @samp{.w} is assumed. | |
5001 | ||
5002 | The byte ordering is target dependent. | |
5003 | ||
5004 | ||
5005 | @ifset COFF | |
5006 | @node Def | |
5007 | @section @code{.def @var{name}} | |
5008 | ||
5009 | @cindex @code{def} directive | |
5010 | @cindex COFF symbols, debugging | |
5011 | @cindex debugging COFF symbols | |
5012 | Begin defining debugging information for a symbol @var{name}; the | |
5013 | definition extends until the @code{.endef} directive is encountered. | |
5014 | @end ifset | |
5015 | ||
5016 | @ifset aout | |
5017 | @node Desc | |
5018 | @section @code{.desc @var{symbol}, @var{abs-expression}} | |
5019 | ||
5020 | @cindex @code{desc} directive | |
5021 | @cindex COFF symbol descriptor | |
5022 | @cindex symbol descriptor, COFF | |
5023 | This directive sets the descriptor of the symbol (@pxref{Symbol Attributes}) | |
5024 | to the low 16 bits of an absolute expression. | |
5025 | ||
5026 | @ifset COFF | |
5027 | The @samp{.desc} directive is not available when @command{@value{AS}} is | |
5028 | configured for COFF output; it is only for @code{a.out} or @code{b.out} | |
5029 | object format. For the sake of compatibility, @command{@value{AS}} accepts | |
5030 | it, but produces no output, when configured for COFF. | |
5031 | @end ifset | |
5032 | @end ifset | |
5033 | ||
5034 | @ifset COFF | |
5035 | @node Dim | |
5036 | @section @code{.dim} | |
5037 | ||
5038 | @cindex @code{dim} directive | |
5039 | @cindex COFF auxiliary symbol information | |
5040 | @cindex auxiliary symbol information, COFF | |
5041 | This directive is generated by compilers to include auxiliary debugging | |
5042 | information in the symbol table. It is only permitted inside | |
5043 | @code{.def}/@code{.endef} pairs. | |
5044 | @end ifset | |
5045 | ||
5046 | @node Double | |
5047 | @section @code{.double @var{flonums}} | |
5048 | ||
5049 | @cindex @code{double} directive | |
5050 | @cindex floating point numbers (double) | |
5051 | @code{.double} expects zero or more flonums, separated by commas. It | |
5052 | assembles floating point numbers. | |
5053 | @ifset GENERIC | |
5054 | The exact kind of floating point numbers emitted depends on how | |
5055 | @command{@value{AS}} is configured. @xref{Machine Dependencies}. | |
5056 | @end ifset | |
5057 | @ifclear GENERIC | |
5058 | @ifset IEEEFLOAT | |
5059 | On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers | |
5060 | in @sc{ieee} format. | |
5061 | @end ifset | |
5062 | @end ifclear | |
5063 | ||
5064 | @node Eject | |
5065 | @section @code{.eject} | |
5066 | ||
5067 | @cindex @code{eject} directive | |
5068 | @cindex new page, in listings | |
5069 | @cindex page, in listings | |
5070 | @cindex listing control: new page | |
5071 | Force a page break at this point, when generating assembly listings. | |
5072 | ||
5073 | @node Else | |
5074 | @section @code{.else} | |
5075 | ||
5076 | @cindex @code{else} directive | |
5077 | @code{.else} is part of the @command{@value{AS}} support for conditional | |
5078 | assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section | |
5079 | of code to be assembled if the condition for the preceding @code{.if} | |
5080 | was false. | |
5081 | ||
5082 | @node Elseif | |
5083 | @section @code{.elseif} | |
5084 | ||
5085 | @cindex @code{elseif} directive | |
5086 | @code{.elseif} is part of the @command{@value{AS}} support for conditional | |
5087 | assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new | |
5088 | @code{.if} block that would otherwise fill the entire @code{.else} section. | |
5089 | ||
5090 | @node End | |
5091 | @section @code{.end} | |
5092 | ||
5093 | @cindex @code{end} directive | |
5094 | @code{.end} marks the end of the assembly file. @command{@value{AS}} does not | |
5095 | process anything in the file past the @code{.end} directive. | |
5096 | ||
5097 | @ifset COFF | |
5098 | @node Endef | |
5099 | @section @code{.endef} | |
5100 | ||
5101 | @cindex @code{endef} directive | |
5102 | This directive flags the end of a symbol definition begun with | |
5103 | @code{.def}. | |
5104 | @end ifset | |
5105 | ||
5106 | @node Endfunc | |
5107 | @section @code{.endfunc} | |
5108 | @cindex @code{endfunc} directive | |
5109 | @code{.endfunc} marks the end of a function specified with @code{.func}. | |
5110 | ||
5111 | @node Endif | |
5112 | @section @code{.endif} | |
5113 | ||
5114 | @cindex @code{endif} directive | |
5115 | @code{.endif} is part of the @command{@value{AS}} support for conditional assembly; | |
5116 | it marks the end of a block of code that is only assembled | |
5117 | conditionally. @xref{If,,@code{.if}}. | |
5118 | ||
5119 | @node Equ | |
5120 | @section @code{.equ @var{symbol}, @var{expression}} | |
5121 | ||
5122 | @cindex @code{equ} directive | |
5123 | @cindex assigning values to symbols | |
5124 | @cindex symbols, assigning values to | |
5125 | This directive sets the value of @var{symbol} to @var{expression}. | |
5126 | It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}. | |
5127 | ||
5128 | @ifset HPPA | |
5129 | The syntax for @code{equ} on the HPPA is | |
5130 | @samp{@var{symbol} .equ @var{expression}}. | |
5131 | @end ifset | |
5132 | ||
5133 | @ifset Z80 | |
5134 | The syntax for @code{equ} on the Z80 is | |
5135 | @samp{@var{symbol} equ @var{expression}}. | |
5136 | On the Z80 it is an error if @var{symbol} is already defined, | |
5137 | but the symbol is not protected from later redefinition. | |
5138 | Compare @ref{Equiv}. | |
5139 | @end ifset | |
5140 | ||
5141 | @node Equiv | |
5142 | @section @code{.equiv @var{symbol}, @var{expression}} | |
5143 | @cindex @code{equiv} directive | |
5144 | The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that | |
5145 | the assembler will signal an error if @var{symbol} is already defined. Note a | |
5146 | symbol which has been referenced but not actually defined is considered to be | |
5147 | undefined. | |
5148 | ||
5149 | Except for the contents of the error message, this is roughly equivalent to | |
5150 | @smallexample | |
5151 | .ifdef SYM | |
5152 | .err | |
5153 | .endif | |
5154 | .equ SYM,VAL | |
5155 | @end smallexample | |
5156 | plus it protects the symbol from later redefinition. | |
5157 | ||
5158 | @node Eqv | |
5159 | @section @code{.eqv @var{symbol}, @var{expression}} | |
5160 | @cindex @code{eqv} directive | |
5161 | The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to | |
5162 | evaluate the expression or any part of it immediately. Instead each time | |
5163 | the resulting symbol is used in an expression, a snapshot of its current | |
5164 | value is taken. | |
5165 | ||
5166 | @node Err | |
5167 | @section @code{.err} | |
5168 | @cindex @code{err} directive | |
5169 | If @command{@value{AS}} assembles a @code{.err} directive, it will print an error | |
5170 | message and, unless the @option{-Z} option was used, it will not generate an | |
5171 | object file. This can be used to signal an error in conditionally compiled code. | |
5172 | ||
5173 | @node Error | |
5174 | @section @code{.error "@var{string}"} | |
5175 | @cindex error directive | |
5176 | ||
5177 | Similarly to @code{.err}, this directive emits an error, but you can specify a | |
5178 | string that will be emitted as the error message. If you don't specify the | |
5179 | message, it defaults to @code{".error directive invoked in source file"}. | |
5180 | @xref{Errors, ,Error and Warning Messages}. | |
5181 | ||
5182 | @smallexample | |
5183 | .error "This code has not been assembled and tested." | |
5184 | @end smallexample | |
5185 | ||
5186 | @node Exitm | |
5187 | @section @code{.exitm} | |
5188 | Exit early from the current macro definition. @xref{Macro}. | |
5189 | ||
5190 | @node Extern | |
5191 | @section @code{.extern} | |
5192 | ||
5193 | @cindex @code{extern} directive | |
5194 | @code{.extern} is accepted in the source program---for compatibility | |
5195 | with other assemblers---but it is ignored. @command{@value{AS}} treats | |
5196 | all undefined symbols as external. | |
5197 | ||
5198 | @node Fail | |
5199 | @section @code{.fail @var{expression}} | |
5200 | ||
5201 | @cindex @code{fail} directive | |
5202 | Generates an error or a warning. If the value of the @var{expression} is 500 | |
5203 | or more, @command{@value{AS}} will print a warning message. If the value is less | |
5204 | than 500, @command{@value{AS}} will print an error message. The message will | |
5205 | include the value of @var{expression}. This can occasionally be useful inside | |
5206 | complex nested macros or conditional assembly. | |
5207 | ||
5208 | @node File | |
5209 | @section @code{.file} | |
5210 | @cindex @code{file} directive | |
5211 | ||
5212 | @ifclear no-file-dir | |
5213 | There are two different versions of the @code{.file} directive. Targets | |
5214 | that support DWARF2 line number information use the DWARF2 version of | |
5215 | @code{.file}. Other targets use the default version. | |
5216 | ||
5217 | @subheading Default Version | |
5218 | ||
5219 | @cindex logical file name | |
5220 | @cindex file name, logical | |
5221 | This version of the @code{.file} directive tells @command{@value{AS}} that we | |
5222 | are about to start a new logical file. The syntax is: | |
5223 | ||
5224 | @smallexample | |
5225 | .file @var{string} | |
5226 | @end smallexample | |
5227 | ||
5228 | @var{string} is the new file name. In general, the filename is | |
5229 | recognized whether or not it is surrounded by quotes @samp{"}; but if you wish | |
5230 | to specify an empty file name, you must give the quotes--@code{""}. This | |
5231 | statement may go away in future: it is only recognized to be compatible with | |
5232 | old @command{@value{AS}} programs. | |
5233 | ||
5234 | @subheading DWARF2 Version | |
5235 | @end ifclear | |
5236 | ||
5237 | When emitting DWARF2 line number information, @code{.file} assigns filenames | |
5238 | to the @code{.debug_line} file name table. The syntax is: | |
5239 | ||
5240 | @smallexample | |
5241 | .file @var{fileno} @var{filename} | |
5242 | @end smallexample | |
5243 | ||
5244 | The @var{fileno} operand should be a unique positive integer to use as the | |
5245 | index of the entry in the table. The @var{filename} operand is a C string | |
5246 | literal. | |
5247 | ||
5248 | The detail of filename indices is exposed to the user because the filename | |
5249 | table is shared with the @code{.debug_info} section of the DWARF2 debugging | |
5250 | information, and thus the user must know the exact indices that table | |
5251 | entries will have. | |
5252 | ||
5253 | @node Fill | |
5254 | @section @code{.fill @var{repeat} , @var{size} , @var{value}} | |
5255 | ||
5256 | @cindex @code{fill} directive | |
5257 | @cindex writing patterns in memory | |
5258 | @cindex patterns, writing in memory | |
5259 | @var{repeat}, @var{size} and @var{value} are absolute expressions. | |
5260 | This emits @var{repeat} copies of @var{size} bytes. @var{Repeat} | |
5261 | may be zero or more. @var{Size} may be zero or more, but if it is | |
5262 | more than 8, then it is deemed to have the value 8, compatible with | |
5263 | other people's assemblers. The contents of each @var{repeat} bytes | |
5264 | is taken from an 8-byte number. The highest order 4 bytes are | |
5265 | zero. The lowest order 4 bytes are @var{value} rendered in the | |
5266 | byte-order of an integer on the computer @command{@value{AS}} is assembling for. | |
5267 | Each @var{size} bytes in a repetition is taken from the lowest order | |
5268 | @var{size} bytes of this number. Again, this bizarre behavior is | |
5269 | compatible with other people's assemblers. | |
5270 | ||
5271 | @var{size} and @var{value} are optional. | |
5272 | If the second comma and @var{value} are absent, @var{value} is | |
5273 | assumed zero. If the first comma and following tokens are absent, | |
5274 | @var{size} is assumed to be 1. | |
5275 | ||
5276 | @node Float | |
5277 | @section @code{.float @var{flonums}} | |
5278 | ||
5279 | @cindex floating point numbers (single) | |
5280 | @cindex @code{float} directive | |
5281 | This directive assembles zero or more flonums, separated by commas. It | |
5282 | has the same effect as @code{.single}. | |
5283 | @ifset GENERIC | |
5284 | The exact kind of floating point numbers emitted depends on how | |
5285 | @command{@value{AS}} is configured. | |
5286 | @xref{Machine Dependencies}. | |
5287 | @end ifset | |
5288 | @ifclear GENERIC | |
5289 | @ifset IEEEFLOAT | |
5290 | On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers | |
5291 | in @sc{ieee} format. | |
5292 | @end ifset | |
5293 | @end ifclear | |
5294 | ||
5295 | @node Func | |
5296 | @section @code{.func @var{name}[,@var{label}]} | |
5297 | @cindex @code{func} directive | |
5298 | @code{.func} emits debugging information to denote function @var{name}, and | |
5299 | is ignored unless the file is assembled with debugging enabled. | |
5300 | Only @samp{--gstabs[+]} is currently supported. | |
5301 | @var{label} is the entry point of the function and if omitted @var{name} | |
5302 | prepended with the @samp{leading char} is used. | |
5303 | @samp{leading char} is usually @code{_} or nothing, depending on the target. | |
5304 | All functions are currently defined to have @code{void} return type. | |
5305 | The function must be terminated with @code{.endfunc}. | |
5306 | ||
5307 | @node Global | |
5308 | @section @code{.global @var{symbol}}, @code{.globl @var{symbol}} | |
5309 | ||
5310 | @cindex @code{global} directive | |
5311 | @cindex symbol, making visible to linker | |
5312 | @code{.global} makes the symbol visible to @code{@value{LD}}. If you define | |
5313 | @var{symbol} in your partial program, its value is made available to | |
5314 | other partial programs that are linked with it. Otherwise, | |
5315 | @var{symbol} takes its attributes from a symbol of the same name | |
5316 | from another file linked into the same program. | |
5317 | ||
5318 | Both spellings (@samp{.globl} and @samp{.global}) are accepted, for | |
5319 | compatibility with other assemblers. | |
5320 | ||
5321 | @ifset HPPA | |
5322 | On the HPPA, @code{.global} is not always enough to make it accessible to other | |
5323 | partial programs. You may need the HPPA-only @code{.EXPORT} directive as well. | |
5324 | @xref{HPPA Directives, ,HPPA Assembler Directives}. | |
5325 | @end ifset | |
5326 | ||
5327 | @ifset ELF | |
5328 | @node Gnu_attribute | |
5329 | @section @code{.gnu_attribute @var{tag},@var{value}} | |
5330 | Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}. | |
5331 | ||
5332 | @node Hidden | |
5333 | @section @code{.hidden @var{names}} | |
5334 | ||
5335 | @cindex @code{hidden} directive | |
5336 | @cindex visibility | |
5337 | This is one of the ELF visibility directives. The other two are | |
5338 | @code{.internal} (@pxref{Internal,,@code{.internal}}) and | |
5339 | @code{.protected} (@pxref{Protected,,@code{.protected}}). | |
5340 | ||
5341 | This directive overrides the named symbols default visibility (which is set by | |
5342 | their binding: local, global or weak). The directive sets the visibility to | |
5343 | @code{hidden} which means that the symbols are not visible to other components. | |
5344 | Such symbols are always considered to be @code{protected} as well. | |
5345 | @end ifset | |
5346 | ||
5347 | @node hword | |
5348 | @section @code{.hword @var{expressions}} | |
5349 | ||
5350 | @cindex @code{hword} directive | |
5351 | @cindex integers, 16-bit | |
5352 | @cindex numbers, 16-bit | |
5353 | @cindex sixteen bit integers | |
5354 | This expects zero or more @var{expressions}, and emits | |
5355 | a 16 bit number for each. | |
5356 | ||
5357 | @ifset GENERIC | |
5358 | This directive is a synonym for @samp{.short}; depending on the target | |
5359 | architecture, it may also be a synonym for @samp{.word}. | |
5360 | @end ifset | |
5361 | @ifclear GENERIC | |
5362 | @ifset W32 | |
5363 | This directive is a synonym for @samp{.short}. | |
5364 | @end ifset | |
5365 | @ifset W16 | |
5366 | This directive is a synonym for both @samp{.short} and @samp{.word}. | |
5367 | @end ifset | |
5368 | @end ifclear | |
5369 | ||
5370 | @node Ident | |
5371 | @section @code{.ident} | |
5372 | ||
5373 | @cindex @code{ident} directive | |
5374 | ||
5375 | This directive is used by some assemblers to place tags in object files. The | |
5376 | behavior of this directive varies depending on the target. When using the | |
5377 | a.out object file format, @command{@value{AS}} simply accepts the directive for | |
5378 | source-file compatibility with existing assemblers, but does not emit anything | |
5379 | for it. When using COFF, comments are emitted to the @code{.comment} or | |
5380 | @code{.rdata} section, depending on the target. When using ELF, comments are | |
5381 | emitted to the @code{.comment} section. | |
5382 | ||
5383 | @node If | |
5384 | @section @code{.if @var{absolute expression}} | |
5385 | ||
5386 | @cindex conditional assembly | |
5387 | @cindex @code{if} directive | |
5388 | @code{.if} marks the beginning of a section of code which is only | |
5389 | considered part of the source program being assembled if the argument | |
5390 | (which must be an @var{absolute expression}) is non-zero. The end of | |
5391 | the conditional section of code must be marked by @code{.endif} | |
5392 | (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the | |
5393 | alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}). | |
5394 | If you have several conditions to check, @code{.elseif} may be used to avoid | |
5395 | nesting blocks if/else within each subsequent @code{.else} block. | |
5396 | ||
5397 | The following variants of @code{.if} are also supported: | |
5398 | @table @code | |
5399 | @cindex @code{ifdef} directive | |
5400 | @item .ifdef @var{symbol} | |
5401 | Assembles the following section of code if the specified @var{symbol} | |
5402 | has been defined. Note a symbol which has been referenced but not yet defined | |
5403 | is considered to be undefined. | |
5404 | ||
5405 | @cindex @code{ifb} directive | |
5406 | @item .ifb @var{text} | |
5407 | Assembles the following section of code if the operand is blank (empty). | |
5408 | ||
5409 | @cindex @code{ifc} directive | |
5410 | @item .ifc @var{string1},@var{string2} | |
5411 | Assembles the following section of code if the two strings are the same. The | |
5412 | strings may be optionally quoted with single quotes. If they are not quoted, | |
5413 | the first string stops at the first comma, and the second string stops at the | |
5414 | end of the line. Strings which contain whitespace should be quoted. The | |
5415 | string comparison is case sensitive. | |
5416 | ||
5417 | @cindex @code{ifeq} directive | |
5418 | @item .ifeq @var{absolute expression} | |
5419 | Assembles the following section of code if the argument is zero. | |
5420 | ||
5421 | @cindex @code{ifeqs} directive | |
5422 | @item .ifeqs @var{string1},@var{string2} | |
5423 | Another form of @code{.ifc}. The strings must be quoted using double quotes. | |
5424 | ||
5425 | @cindex @code{ifge} directive | |
5426 | @item .ifge @var{absolute expression} | |
5427 | Assembles the following section of code if the argument is greater than or | |
5428 | equal to zero. | |
5429 | ||
5430 | @cindex @code{ifgt} directive | |
5431 | @item .ifgt @var{absolute expression} | |
5432 | Assembles the following section of code if the argument is greater than zero. | |
5433 | ||
5434 | @cindex @code{ifle} directive | |
5435 | @item .ifle @var{absolute expression} | |
5436 | Assembles the following section of code if the argument is less than or equal | |
5437 | to zero. | |
5438 | ||
5439 | @cindex @code{iflt} directive | |
5440 | @item .iflt @var{absolute expression} | |
5441 | Assembles the following section of code if the argument is less than zero. | |
5442 | ||
5443 | @cindex @code{ifnb} directive | |
5444 | @item .ifnb @var{text} | |
5445 | Like @code{.ifb}, but the sense of the test is reversed: this assembles the | |
5446 | following section of code if the operand is non-blank (non-empty). | |
5447 | ||
5448 | @cindex @code{ifnc} directive | |
5449 | @item .ifnc @var{string1},@var{string2}. | |
5450 | Like @code{.ifc}, but the sense of the test is reversed: this assembles the | |
5451 | following section of code if the two strings are not the same. | |
5452 | ||
5453 | @cindex @code{ifndef} directive | |
5454 | @cindex @code{ifnotdef} directive | |
5455 | @item .ifndef @var{symbol} | |
5456 | @itemx .ifnotdef @var{symbol} | |
5457 | Assembles the following section of code if the specified @var{symbol} | |
5458 | has not been defined. Both spelling variants are equivalent. Note a symbol | |
5459 | which has been referenced but not yet defined is considered to be undefined. | |
5460 | ||
5461 | @cindex @code{ifne} directive | |
5462 | @item .ifne @var{absolute expression} | |
5463 | Assembles the following section of code if the argument is not equal to zero | |
5464 | (in other words, this is equivalent to @code{.if}). | |
5465 | ||
5466 | @cindex @code{ifnes} directive | |
5467 | @item .ifnes @var{string1},@var{string2} | |
5468 | Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the | |
5469 | following section of code if the two strings are not the same. | |
5470 | @end table | |
5471 | ||
5472 | @node Incbin | |
5473 | @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]} | |
5474 | ||
5475 | @cindex @code{incbin} directive | |
5476 | @cindex binary files, including | |
5477 | The @code{incbin} directive includes @var{file} verbatim at the current | |
5478 | location. You can control the search paths used with the @samp{-I} command-line | |
5479 | option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required | |
5480 | around @var{file}. | |
5481 | ||
5482 | The @var{skip} argument skips a number of bytes from the start of the | |
5483 | @var{file}. The @var{count} argument indicates the maximum number of bytes to | |
5484 | read. Note that the data is not aligned in any way, so it is the user's | |
5485 | responsibility to make sure that proper alignment is provided both before and | |
5486 | after the @code{incbin} directive. | |
5487 | ||
5488 | @node Include | |
5489 | @section @code{.include "@var{file}"} | |
5490 | ||
5491 | @cindex @code{include} directive | |
5492 | @cindex supporting files, including | |
5493 | @cindex files, including | |
5494 | This directive provides a way to include supporting files at specified | |
5495 | points in your source program. The code from @var{file} is assembled as | |
5496 | if it followed the point of the @code{.include}; when the end of the | |
5497 | included file is reached, assembly of the original file continues. You | |
5498 | can control the search paths used with the @samp{-I} command-line option | |
5499 | (@pxref{Invoking,,Command-Line Options}). Quotation marks are required | |
5500 | around @var{file}. | |
5501 | ||
5502 | @node Int | |
5503 | @section @code{.int @var{expressions}} | |
5504 | ||
5505 | @cindex @code{int} directive | |
5506 | @cindex integers, 32-bit | |
5507 | Expect zero or more @var{expressions}, of any section, separated by commas. | |
5508 | For each expression, emit a number that, at run time, is the value of that | |
5509 | expression. The byte order and bit size of the number depends on what kind | |
5510 | of target the assembly is for. | |
5511 | ||
5512 | @ifclear GENERIC | |
5513 | @ifset H8 | |
5514 | On most forms of the H8/300, @code{.int} emits 16-bit | |
5515 | integers. On the H8/300H and the Renesas SH, however, @code{.int} emits | |
5516 | 32-bit integers. | |
5517 | @end ifset | |
5518 | @end ifclear | |
5519 | ||
5520 | @ifset ELF | |
5521 | @node Internal | |
5522 | @section @code{.internal @var{names}} | |
5523 | ||
5524 | @cindex @code{internal} directive | |
5525 | @cindex visibility | |
5526 | This is one of the ELF visibility directives. The other two are | |
5527 | @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and | |
5528 | @code{.protected} (@pxref{Protected,,@code{.protected}}). | |
5529 | ||
5530 | This directive overrides the named symbols default visibility (which is set by | |
5531 | their binding: local, global or weak). The directive sets the visibility to | |
5532 | @code{internal} which means that the symbols are considered to be @code{hidden} | |
5533 | (i.e., not visible to other components), and that some extra, processor specific | |
5534 | processing must also be performed upon the symbols as well. | |
5535 | @end ifset | |
5536 | ||
5537 | @node Irp | |
5538 | @section @code{.irp @var{symbol},@var{values}}@dots{} | |
5539 | ||
5540 | @cindex @code{irp} directive | |
5541 | Evaluate a sequence of statements assigning different values to @var{symbol}. | |
5542 | The sequence of statements starts at the @code{.irp} directive, and is | |
5543 | terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is | |
5544 | set to @var{value}, and the sequence of statements is assembled. If no | |
5545 | @var{value} is listed, the sequence of statements is assembled once, with | |
5546 | @var{symbol} set to the null string. To refer to @var{symbol} within the | |
5547 | sequence of statements, use @var{\symbol}. | |
5548 | ||
5549 | For example, assembling | |
5550 | ||
5551 | @example | |
5552 | .irp param,1,2,3 | |
5553 | move d\param,sp@@- | |
5554 | .endr | |
5555 | @end example | |
5556 | ||
5557 | is equivalent to assembling | |
5558 | ||
5559 | @example | |
5560 | move d1,sp@@- | |
5561 | move d2,sp@@- | |
5562 | move d3,sp@@- | |
5563 | @end example | |
5564 | ||
5565 | For some caveats with the spelling of @var{symbol}, see also @ref{Macro}. | |
5566 | ||
5567 | @node Irpc | |
5568 | @section @code{.irpc @var{symbol},@var{values}}@dots{} | |
5569 | ||
5570 | @cindex @code{irpc} directive | |
5571 | Evaluate a sequence of statements assigning different values to @var{symbol}. | |
5572 | The sequence of statements starts at the @code{.irpc} directive, and is | |
5573 | terminated by an @code{.endr} directive. For each character in @var{value}, | |
5574 | @var{symbol} is set to the character, and the sequence of statements is | |
5575 | assembled. If no @var{value} is listed, the sequence of statements is | |
5576 | assembled once, with @var{symbol} set to the null string. To refer to | |
5577 | @var{symbol} within the sequence of statements, use @var{\symbol}. | |
5578 | ||
5579 | For example, assembling | |
5580 | ||
5581 | @example | |
5582 | .irpc param,123 | |
5583 | move d\param,sp@@- | |
5584 | .endr | |
5585 | @end example | |
5586 | ||
5587 | is equivalent to assembling | |
5588 | ||
5589 | @example | |
5590 | move d1,sp@@- | |
5591 | move d2,sp@@- | |
5592 | move d3,sp@@- | |
5593 | @end example | |
5594 | ||
5595 | For some caveats with the spelling of @var{symbol}, see also the discussion | |
5596 | at @xref{Macro}. | |
5597 | ||
5598 | @node Lcomm | |
5599 | @section @code{.lcomm @var{symbol} , @var{length}} | |
5600 | ||
5601 | @cindex @code{lcomm} directive | |
5602 | @cindex local common symbols | |
5603 | @cindex symbols, local common | |
5604 | Reserve @var{length} (an absolute expression) bytes for a local common | |
5605 | denoted by @var{symbol}. The section and value of @var{symbol} are | |
5606 | those of the new local common. The addresses are allocated in the bss | |
5607 | section, so that at run-time the bytes start off zeroed. @var{Symbol} | |
5608 | is not declared global (@pxref{Global,,@code{.global}}), so is normally | |
5609 | not visible to @code{@value{LD}}. | |
5610 | ||
5611 | @ifset GENERIC | |
5612 | Some targets permit a third argument to be used with @code{.lcomm}. This | |
5613 | argument specifies the desired alignment of the symbol in the bss section. | |
5614 | @end ifset | |
5615 | ||
5616 | @ifset HPPA | |
5617 | The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is | |
5618 | @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional. | |
5619 | @end ifset | |
5620 | ||
5621 | @node Lflags | |
5622 | @section @code{.lflags} | |
5623 | ||
5624 | @cindex @code{lflags} directive (ignored) | |
5625 | @command{@value{AS}} accepts this directive, for compatibility with other | |
5626 | assemblers, but ignores it. | |
5627 | ||
5628 | @ifclear no-line-dir | |
5629 | @node Line | |
5630 | @section @code{.line @var{line-number}} | |
5631 | ||
5632 | @cindex @code{line} directive | |
5633 | @cindex logical line number | |
5634 | @ifset aout | |
5635 | Change the logical line number. @var{line-number} must be an absolute | |
5636 | expression. The next line has that logical line number. Therefore any other | |
5637 | statements on the current line (after a statement separator character) are | |
5638 | reported as on logical line number @var{line-number} @minus{} 1. One day | |
5639 | @command{@value{AS}} will no longer support this directive: it is recognized only | |
5640 | for compatibility with existing assembler programs. | |
5641 | @end ifset | |
5642 | ||
5643 | Even though this is a directive associated with the @code{a.out} or | |
5644 | @code{b.out} object-code formats, @command{@value{AS}} still recognizes it | |
5645 | when producing COFF output, and treats @samp{.line} as though it | |
5646 | were the COFF @samp{.ln} @emph{if} it is found outside a | |
5647 | @code{.def}/@code{.endef} pair. | |
5648 | ||
5649 | Inside a @code{.def}, @samp{.line} is, instead, one of the directives | |
5650 | used by compilers to generate auxiliary symbol information for | |
5651 | debugging. | |
5652 | @end ifclear | |
5653 | ||
5654 | @node Linkonce | |
5655 | @section @code{.linkonce [@var{type}]} | |
5656 | @cindex COMDAT | |
5657 | @cindex @code{linkonce} directive | |
5658 | @cindex common sections | |
5659 | Mark the current section so that the linker only includes a single copy of it. | |
5660 | This may be used to include the same section in several different object files, | |
5661 | but ensure that the linker will only include it once in the final output file. | |
5662 | The @code{.linkonce} pseudo-op must be used for each instance of the section. | |
5663 | Duplicate sections are detected based on the section name, so it should be | |
5664 | unique. | |
5665 | ||
5666 | This directive is only supported by a few object file formats; as of this | |
5667 | writing, the only object file format which supports it is the Portable | |
5668 | Executable format used on Windows NT. | |
5669 | ||
5670 | The @var{type} argument is optional. If specified, it must be one of the | |
5671 | following strings. For example: | |
5672 | @smallexample | |
5673 | .linkonce same_size | |
5674 | @end smallexample | |
5675 | Not all types may be supported on all object file formats. | |
5676 | ||
5677 | @table @code | |
5678 | @item discard | |
5679 | Silently discard duplicate sections. This is the default. | |
5680 | ||
5681 | @item one_only | |
5682 | Warn if there are duplicate sections, but still keep only one copy. | |
5683 | ||
5684 | @item same_size | |
5685 | Warn if any of the duplicates have different sizes. | |
5686 | ||
5687 | @item same_contents | |
5688 | Warn if any of the duplicates do not have exactly the same contents. | |
5689 | @end table | |
5690 | ||
5691 | @node List | |
5692 | @section @code{.list} | |
5693 | ||
5694 | @cindex @code{list} directive | |
5695 | @cindex listing control, turning on | |
5696 | Control (in conjunction with the @code{.nolist} directive) whether or | |
5697 | not assembly listings are generated. These two directives maintain an | |
5698 | internal counter (which is zero initially). @code{.list} increments the | |
5699 | counter, and @code{.nolist} decrements it. Assembly listings are | |
5700 | generated whenever the counter is greater than zero. | |
5701 | ||
5702 | By default, listings are disabled. When you enable them (with the | |
5703 | @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}), | |
5704 | the initial value of the listing counter is one. | |
5705 | ||
5706 | @node Ln | |
5707 | @section @code{.ln @var{line-number}} | |
5708 | ||
5709 | @cindex @code{ln} directive | |
5710 | @ifclear no-line-dir | |
5711 | @samp{.ln} is a synonym for @samp{.line}. | |
5712 | @end ifclear | |
5713 | @ifset no-line-dir | |
5714 | Tell @command{@value{AS}} to change the logical line number. @var{line-number} | |
5715 | must be an absolute expression. The next line has that logical | |
5716 | line number, so any other statements on the current line (after a | |
5717 | statement separator character @code{;}) are reported as on logical | |
5718 | line number @var{line-number} @minus{} 1. | |
5719 | @end ifset | |
5720 | ||
5721 | @node Loc | |
5722 | @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]} | |
5723 | @cindex @code{loc} directive | |
5724 | When emitting DWARF2 line number information, | |
5725 | the @code{.loc} directive will add a row to the @code{.debug_line} line | |
5726 | number matrix corresponding to the immediately following assembly | |
5727 | instruction. The @var{fileno}, @var{lineno}, and optional @var{column} | |
5728 | arguments will be applied to the @code{.debug_line} state machine before | |
5729 | the row is added. | |
5730 | ||
5731 | The @var{options} are a sequence of the following tokens in any order: | |
5732 | ||
5733 | @table @code | |
5734 | @item basic_block | |
5735 | This option will set the @code{basic_block} register in the | |
5736 | @code{.debug_line} state machine to @code{true}. | |
5737 | ||
5738 | @item prologue_end | |
5739 | This option will set the @code{prologue_end} register in the | |
5740 | @code{.debug_line} state machine to @code{true}. | |
5741 | ||
5742 | @item epilogue_begin | |
5743 | This option will set the @code{epilogue_begin} register in the | |
5744 | @code{.debug_line} state machine to @code{true}. | |
5745 | ||
5746 | @item is_stmt @var{value} | |
5747 | This option will set the @code{is_stmt} register in the | |
5748 | @code{.debug_line} state machine to @code{value}, which must be | |
5749 | either 0 or 1. | |
5750 | ||
5751 | @item isa @var{value} | |
5752 | This directive will set the @code{isa} register in the @code{.debug_line} | |
5753 | state machine to @var{value}, which must be an unsigned integer. | |
5754 | ||
5755 | @item discriminator @var{value} | |
5756 | This directive will set the @code{discriminator} register in the @code{.debug_line} | |
5757 | state machine to @var{value}, which must be an unsigned integer. | |
5758 | ||
5759 | @item view @var{value} | |
5760 | This option causes a row to be added to @code{.debug_line} in reference to the | |
5761 | current address (which might not be the same as that of the following assembly | |
5762 | instruction), and to associate @var{value} with the @code{view} register in the | |
5763 | @code{.debug_line} state machine. If @var{value} is a label, both the | |
5764 | @code{view} register and the label are set to the number of prior @code{.loc} | |
5765 | directives at the same program location. If @var{value} is the literal | |
5766 | @code{0}, the @code{view} register is set to zero, and the assembler asserts | |
5767 | that there aren't any prior @code{.loc} directives at the same program | |
5768 | location. If @var{value} is the literal @code{-0}, the assembler arrange for | |
5769 | the @code{view} register to be reset in this row, even if there are prior | |
5770 | @code{.loc} directives at the same program location. | |
5771 | ||
5772 | @end table | |
5773 | ||
5774 | @node Loc_mark_labels | |
5775 | @section @code{.loc_mark_labels @var{enable}} | |
5776 | @cindex @code{loc_mark_labels} directive | |
5777 | When emitting DWARF2 line number information, | |
5778 | the @code{.loc_mark_labels} directive makes the assembler emit an entry | |
5779 | to the @code{.debug_line} line number matrix with the @code{basic_block} | |
5780 | register in the state machine set whenever a code label is seen. | |
5781 | The @var{enable} argument should be either 1 or 0, to enable or disable | |
5782 | this function respectively. | |
5783 | ||
5784 | @ifset ELF | |
5785 | @node Local | |
5786 | @section @code{.local @var{names}} | |
5787 | ||
5788 | @cindex @code{local} directive | |
5789 | This directive, which is available for ELF targets, marks each symbol in | |
5790 | the comma-separated list of @code{names} as a local symbol so that it | |
5791 | will not be externally visible. If the symbols do not already exist, | |
5792 | they will be created. | |
5793 | ||
5794 | For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not | |
5795 | accept an alignment argument, which is the case for most ELF targets, | |
5796 | the @code{.local} directive can be used in combination with @code{.comm} | |
5797 | (@pxref{Comm}) to define aligned local common data. | |
5798 | @end ifset | |
5799 | ||
5800 | @node Long | |
5801 | @section @code{.long @var{expressions}} | |
5802 | ||
5803 | @cindex @code{long} directive | |
5804 | @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}. | |
5805 | ||
5806 | @ignore | |
5807 | @c no one seems to know what this is for or whether this description is | |
5808 | @c what it really ought to do | |
5809 | @node Lsym | |
5810 | @section @code{.lsym @var{symbol}, @var{expression}} | |
5811 | ||
5812 | @cindex @code{lsym} directive | |
5813 | @cindex symbol, not referenced in assembly | |
5814 | @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in | |
5815 | the hash table, ensuring it cannot be referenced by name during the | |
5816 | rest of the assembly. This sets the attributes of the symbol to be | |
5817 | the same as the expression value: | |
5818 | @smallexample | |
5819 | @var{other} = @var{descriptor} = 0 | |
5820 | @var{type} = @r{(section of @var{expression})} | |
5821 | @var{value} = @var{expression} | |
5822 | @end smallexample | |
5823 | @noindent | |
5824 | The new symbol is not flagged as external. | |
5825 | @end ignore | |
5826 | ||
5827 | @node Macro | |
5828 | @section @code{.macro} | |
5829 | ||
5830 | @cindex macros | |
5831 | The commands @code{.macro} and @code{.endm} allow you to define macros that | |
5832 | generate assembly output. For example, this definition specifies a macro | |
5833 | @code{sum} that puts a sequence of numbers into memory: | |
5834 | ||
5835 | @example | |
5836 | .macro sum from=0, to=5 | |
5837 | .long \from | |
5838 | .if \to-\from | |
5839 | sum "(\from+1)",\to | |
5840 | .endif | |
5841 | .endm | |
5842 | @end example | |
5843 | ||
5844 | @noindent | |
5845 | With that definition, @samp{SUM 0,5} is equivalent to this assembly input: | |
5846 | ||
5847 | @example | |
5848 | .long 0 | |
5849 | .long 1 | |
5850 | .long 2 | |
5851 | .long 3 | |
5852 | .long 4 | |
5853 | .long 5 | |
5854 | @end example | |
5855 | ||
5856 | @ftable @code | |
5857 | @item .macro @var{macname} | |
5858 | @itemx .macro @var{macname} @var{macargs} @dots{} | |
5859 | @cindex @code{macro} directive | |
5860 | Begin the definition of a macro called @var{macname}. If your macro | |
5861 | definition requires arguments, specify their names after the macro name, | |
5862 | separated by commas or spaces. You can qualify the macro argument to | |
5863 | indicate whether all invocations must specify a non-blank value (through | |
5864 | @samp{:@code{req}}), or whether it takes all of the remaining arguments | |
5865 | (through @samp{:@code{vararg}}). You can supply a default value for any | |
5866 | macro argument by following the name with @samp{=@var{deflt}}. You | |
5867 | cannot define two macros with the same @var{macname} unless it has been | |
5868 | subject to the @code{.purgem} directive (@pxref{Purgem}) between the two | |
5869 | definitions. For example, these are all valid @code{.macro} statements: | |
5870 | ||
5871 | @table @code | |
5872 | @item .macro comm | |
5873 | Begin the definition of a macro called @code{comm}, which takes no | |
5874 | arguments. | |
5875 | ||
5876 | @item .macro plus1 p, p1 | |
5877 | @itemx .macro plus1 p p1 | |
5878 | Either statement begins the definition of a macro called @code{plus1}, | |
5879 | which takes two arguments; within the macro definition, write | |
5880 | @samp{\p} or @samp{\p1} to evaluate the arguments. | |
5881 | ||
5882 | @item .macro reserve_str p1=0 p2 | |
5883 | Begin the definition of a macro called @code{reserve_str}, with two | |
5884 | arguments. The first argument has a default value, but not the second. | |
5885 | After the definition is complete, you can call the macro either as | |
5886 | @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to | |
5887 | @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str | |
5888 | ,@var{b}} (with @samp{\p1} evaluating as the default, in this case | |
5889 | @samp{0}, and @samp{\p2} evaluating to @var{b}). | |
5890 | ||
5891 | @item .macro m p1:req, p2=0, p3:vararg | |
5892 | Begin the definition of a macro called @code{m}, with at least three | |
5893 | arguments. The first argument must always have a value specified, but | |
5894 | not the second, which instead has a default value. The third formal | |
5895 | will get assigned all remaining arguments specified at invocation time. | |
5896 | ||
5897 | When you call a macro, you can specify the argument values either by | |
5898 | position, or by keyword. For example, @samp{sum 9,17} is equivalent to | |
5899 | @samp{sum to=17, from=9}. | |
5900 | ||
5901 | @end table | |
5902 | ||
5903 | Note that since each of the @var{macargs} can be an identifier exactly | |
5904 | as any other one permitted by the target architecture, there may be | |
5905 | occasional problems if the target hand-crafts special meanings to certain | |
5906 | characters when they occur in a special position. For example, if the colon | |
5907 | (@code{:}) is generally permitted to be part of a symbol name, but the | |
5908 | architecture specific code special-cases it when occurring as the final | |
5909 | character of a symbol (to denote a label), then the macro parameter | |
5910 | replacement code will have no way of knowing that and consider the whole | |
5911 | construct (including the colon) an identifier, and check only this | |
5912 | identifier for being the subject to parameter substitution. So for example | |
5913 | this macro definition: | |
5914 | ||
5915 | @example | |
5916 | .macro label l | |
5917 | \l: | |
5918 | .endm | |
5919 | @end example | |
5920 | ||
5921 | might not work as expected. Invoking @samp{label foo} might not create a label | |
5922 | called @samp{foo} but instead just insert the text @samp{\l:} into the | |
5923 | assembler source, probably generating an error about an unrecognised | |
5924 | identifier. | |
5925 | ||
5926 | Similarly problems might occur with the period character (@samp{.}) | |
5927 | which is often allowed inside opcode names (and hence identifier names). So | |
5928 | for example constructing a macro to build an opcode from a base name and a | |
5929 | length specifier like this: | |
5930 | ||
5931 | @example | |
5932 | .macro opcode base length | |
5933 | \base.\length | |
5934 | .endm | |
5935 | @end example | |
5936 | ||
5937 | and invoking it as @samp{opcode store l} will not create a @samp{store.l} | |
5938 | instruction but instead generate some kind of error as the assembler tries to | |
5939 | interpret the text @samp{\base.\length}. | |
5940 | ||
5941 | There are several possible ways around this problem: | |
5942 | ||
5943 | @table @code | |
5944 | @item Insert white space | |
5945 | If it is possible to use white space characters then this is the simplest | |
5946 | solution. eg: | |
5947 | ||
5948 | @example | |
5949 | .macro label l | |
5950 | \l : | |
5951 | .endm | |
5952 | @end example | |
5953 | ||
5954 | @item Use @samp{\()} | |
5955 | The string @samp{\()} can be used to separate the end of a macro argument from | |
5956 | the following text. eg: | |
5957 | ||
5958 | @example | |
5959 | .macro opcode base length | |
5960 | \base\().\length | |
5961 | .endm | |
5962 | @end example | |
5963 | ||
5964 | @item Use the alternate macro syntax mode | |
5965 | In the alternative macro syntax mode the ampersand character (@samp{&}) can be | |
5966 | used as a separator. eg: | |
5967 | ||
5968 | @example | |
5969 | .altmacro | |
5970 | .macro label l | |
5971 | l&: | |
5972 | .endm | |
5973 | @end example | |
5974 | @end table | |
5975 | ||
5976 | Note: this problem of correctly identifying string parameters to pseudo ops | |
5977 | also applies to the identifiers used in @code{.irp} (@pxref{Irp}) | |
5978 | and @code{.irpc} (@pxref{Irpc}) as well. | |
5979 | ||
5980 | @item .endm | |
5981 | @cindex @code{endm} directive | |
5982 | Mark the end of a macro definition. | |
5983 | ||
5984 | @item .exitm | |
5985 | @cindex @code{exitm} directive | |
5986 | Exit early from the current macro definition. | |
5987 | ||
5988 | @cindex number of macros executed | |
5989 | @cindex macros, count executed | |
5990 | @item \@@ | |
5991 | @command{@value{AS}} maintains a counter of how many macros it has | |
5992 | executed in this pseudo-variable; you can copy that number to your | |
5993 | output with @samp{\@@}, but @emph{only within a macro definition}. | |
5994 | ||
5995 | @item LOCAL @var{name} [ , @dots{} ] | |
5996 | @emph{Warning: @code{LOCAL} is only available if you select ``alternate | |
5997 | macro syntax'' with @samp{--alternate} or @code{.altmacro}.} | |
5998 | @xref{Altmacro,,@code{.altmacro}}. | |
5999 | @end ftable | |
6000 | ||
6001 | @node MRI | |
6002 | @section @code{.mri @var{val}} | |
6003 | ||
6004 | @cindex @code{mri} directive | |
6005 | @cindex MRI mode, temporarily | |
6006 | If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If | |
6007 | @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change | |
6008 | affects code assembled until the next @code{.mri} directive, or until the end | |
6009 | of the file. @xref{M, MRI mode, MRI mode}. | |
6010 | ||
6011 | @node Noaltmacro | |
6012 | @section @code{.noaltmacro} | |
6013 | Disable alternate macro mode. @xref{Altmacro}. | |
6014 | ||
6015 | @node Nolist | |
6016 | @section @code{.nolist} | |
6017 | ||
6018 | @cindex @code{nolist} directive | |
6019 | @cindex listing control, turning off | |
6020 | Control (in conjunction with the @code{.list} directive) whether or | |
6021 | not assembly listings are generated. These two directives maintain an | |
6022 | internal counter (which is zero initially). @code{.list} increments the | |
6023 | counter, and @code{.nolist} decrements it. Assembly listings are | |
6024 | generated whenever the counter is greater than zero. | |
6025 | ||
6026 | @node Nops | |
6027 | @section @code{.nops @var{size}[, @var{control}]} | |
6028 | ||
6029 | @cindex @code{nops} directive | |
6030 | @cindex filling memory with no-op instructions | |
6031 | This directive emits @var{size} bytes filled with no-op instructions. | |
6032 | @var{size} is absolute expression, which must be a positve value. | |
6033 | @var{control} controls how no-op instructions should be generated. If | |
6034 | the comma and @var{control} are omitted, @var{control} is assumed to be | |
6035 | zero. | |
6036 | ||
6037 | Note: For Intel 80386 and AMD x86-64 targets, @var{control} specifies | |
6038 | the size limit of a no-op instruction. The valid values of @var{control} | |
6039 | are between 0 and 4 in 16-bit mode, between 0 and 7 when tuning for | |
6040 | older processors in 32-bit mode, between 0 and 11 in 64-bit mode or when | |
6041 | tuning for newer processors in 32-bit mode. When 0 is used, the no-op | |
6042 | instruction size limit is set to the maximum supported size. | |
6043 | ||
6044 | @node Octa | |
6045 | @section @code{.octa @var{bignums}} | |
6046 | ||
6047 | @c FIXME: double size emitted for "octa" on some? Or warn? | |
6048 | @cindex @code{octa} directive | |
6049 | @cindex integer, 16-byte | |
6050 | @cindex sixteen byte integer | |
6051 | This directive expects zero or more bignums, separated by commas. For each | |
6052 | bignum, it emits a 16-byte integer. | |
6053 | ||
6054 | The term ``octa'' comes from contexts in which a ``word'' is two bytes; | |
6055 | hence @emph{octa}-word for 16 bytes. | |
6056 | ||
6057 | @node Offset | |
6058 | @section @code{.offset @var{loc}} | |
6059 | ||
6060 | @cindex @code{offset} directive | |
6061 | Set the location counter to @var{loc} in the absolute section. @var{loc} must | |
6062 | be an absolute expression. This directive may be useful for defining | |
6063 | symbols with absolute values. Do not confuse it with the @code{.org} | |
6064 | directive. | |
6065 | ||
6066 | @node Org | |
6067 | @section @code{.org @var{new-lc} , @var{fill}} | |
6068 | ||
6069 | @cindex @code{org} directive | |
6070 | @cindex location counter, advancing | |
6071 | @cindex advancing location counter | |
6072 | @cindex current address, advancing | |
6073 | Advance the location counter of the current section to | |
6074 | @var{new-lc}. @var{new-lc} is either an absolute expression or an | |
6075 | expression with the same section as the current subsection. That is, | |
6076 | you can't use @code{.org} to cross sections: if @var{new-lc} has the | |
6077 | wrong section, the @code{.org} directive is ignored. To be compatible | |
6078 | with former assemblers, if the section of @var{new-lc} is absolute, | |
6079 | @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc} | |
6080 | is the same as the current subsection. | |
6081 | ||
6082 | @code{.org} may only increase the location counter, or leave it | |
6083 | unchanged; you cannot use @code{.org} to move the location counter | |
6084 | backwards. | |
6085 | ||
6086 | @c double negative used below "not undefined" because this is a specific | |
6087 | @c reference to "undefined" (as SEG_UNKNOWN is called in this manual) | |
6088 | @c section. doc@cygnus.com 18feb91 | |
6089 | Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc} | |
6090 | may not be undefined. If you really detest this restriction we eagerly await | |
6091 | a chance to share your improved assembler. | |
6092 | ||
6093 | Beware that the origin is relative to the start of the section, not | |
6094 | to the start of the subsection. This is compatible with other | |
6095 | people's assemblers. | |
6096 | ||
6097 | When the location counter (of the current subsection) is advanced, the | |
6098 | intervening bytes are filled with @var{fill} which should be an | |
6099 | absolute expression. If the comma and @var{fill} are omitted, | |
6100 | @var{fill} defaults to zero. | |
6101 | ||
6102 | @node P2align | |
6103 | @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} | |
6104 | ||
6105 | @cindex padding the location counter given a power of two | |
6106 | @cindex @code{p2align} directive | |
6107 | Pad the location counter (in the current subsection) to a particular | |
6108 | storage boundary. The first expression (which must be absolute) is the | |
6109 | number of low-order zero bits the location counter must have after | |
6110 | advancement. For example @samp{.p2align 3} advances the location | |
6111 | counter until it a multiple of 8. If the location counter is already a | |
6112 | multiple of 8, no change is needed. | |
6113 | ||
6114 | The second expression (also absolute) gives the fill value to be stored in the | |
6115 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
6116 | padding bytes are normally zero. However, on most systems, if the section is | |
6117 | marked as containing code and the fill value is omitted, the space is filled | |
6118 | with no-op instructions. | |
6119 | ||
6120 | The third expression is also absolute, and is also optional. If it is present, | |
6121 | it is the maximum number of bytes that should be skipped by this alignment | |
6122 | directive. If doing the alignment would require skipping more bytes than the | |
6123 | specified maximum, then the alignment is not done at all. You can omit the | |
6124 | fill value (the second argument) entirely by simply using two commas after the | |
6125 | required alignment; this can be useful if you want the alignment to be filled | |
6126 | with no-op instructions when appropriate. | |
6127 | ||
6128 | @cindex @code{p2alignw} directive | |
6129 | @cindex @code{p2alignl} directive | |
6130 | The @code{.p2alignw} and @code{.p2alignl} directives are variants of the | |
6131 | @code{.p2align} directive. The @code{.p2alignw} directive treats the fill | |
6132 | pattern as a two byte word value. The @code{.p2alignl} directives treats the | |
6133 | fill pattern as a four byte longword value. For example, @code{.p2alignw | |
6134 | 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be | |
6135 | filled in with the value 0x368d (the exact placement of the bytes depends upon | |
6136 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is | |
6137 | undefined. | |
6138 | ||
6139 | @ifset ELF | |
6140 | @node PopSection | |
6141 | @section @code{.popsection} | |
6142 | ||
6143 | @cindex @code{popsection} directive | |
6144 | @cindex Section Stack | |
6145 | This is one of the ELF section stack manipulation directives. The others are | |
6146 | @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}), | |
6147 | @code{.pushsection} (@pxref{PushSection}), and @code{.previous} | |
6148 | (@pxref{Previous}). | |
6149 | ||
6150 | This directive replaces the current section (and subsection) with the top | |
6151 | section (and subsection) on the section stack. This section is popped off the | |
6152 | stack. | |
6153 | @end ifset | |
6154 | ||
6155 | @ifset ELF | |
6156 | @node Previous | |
6157 | @section @code{.previous} | |
6158 | ||
6159 | @cindex @code{previous} directive | |
6160 | @cindex Section Stack | |
6161 | This is one of the ELF section stack manipulation directives. The others are | |
6162 | @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}), | |
6163 | @code{.pushsection} (@pxref{PushSection}), and @code{.popsection} | |
6164 | (@pxref{PopSection}). | |
6165 | ||
6166 | This directive swaps the current section (and subsection) with most recently | |
6167 | referenced section/subsection pair prior to this one. Multiple | |
6168 | @code{.previous} directives in a row will flip between two sections (and their | |
6169 | subsections). For example: | |
6170 | ||
6171 | @smallexample | |
6172 | .section A | |
6173 | .subsection 1 | |
6174 | .word 0x1234 | |
6175 | .subsection 2 | |
6176 | .word 0x5678 | |
6177 | .previous | |
6178 | .word 0x9abc | |
6179 | @end smallexample | |
6180 | ||
6181 | Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of | |
6182 | section A. Whilst: | |
6183 | ||
6184 | @smallexample | |
6185 | .section A | |
6186 | .subsection 1 | |
6187 | # Now in section A subsection 1 | |
6188 | .word 0x1234 | |
6189 | .section B | |
6190 | .subsection 0 | |
6191 | # Now in section B subsection 0 | |
6192 | .word 0x5678 | |
6193 | .subsection 1 | |
6194 | # Now in section B subsection 1 | |
6195 | .word 0x9abc | |
6196 | .previous | |
6197 | # Now in section B subsection 0 | |
6198 | .word 0xdef0 | |
6199 | @end smallexample | |
6200 | ||
6201 | Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of | |
6202 | section B and 0x9abc into subsection 1 of section B. | |
6203 | ||
6204 | In terms of the section stack, this directive swaps the current section with | |
6205 | the top section on the section stack. | |
6206 | @end ifset | |
6207 | ||
6208 | @node Print | |
6209 | @section @code{.print @var{string}} | |
6210 | ||
6211 | @cindex @code{print} directive | |
6212 | @command{@value{AS}} will print @var{string} on the standard output during | |
6213 | assembly. You must put @var{string} in double quotes. | |
6214 | ||
6215 | @ifset ELF | |
6216 | @node Protected | |
6217 | @section @code{.protected @var{names}} | |
6218 | ||
6219 | @cindex @code{protected} directive | |
6220 | @cindex visibility | |
6221 | This is one of the ELF visibility directives. The other two are | |
6222 | @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}). | |
6223 | ||
6224 | This directive overrides the named symbols default visibility (which is set by | |
6225 | their binding: local, global or weak). The directive sets the visibility to | |
6226 | @code{protected} which means that any references to the symbols from within the | |
6227 | components that defines them must be resolved to the definition in that | |
6228 | component, even if a definition in another component would normally preempt | |
6229 | this. | |
6230 | @end ifset | |
6231 | ||
6232 | @node Psize | |
6233 | @section @code{.psize @var{lines} , @var{columns}} | |
6234 | ||
6235 | @cindex @code{psize} directive | |
6236 | @cindex listing control: paper size | |
6237 | @cindex paper size, for listings | |
6238 | Use this directive to declare the number of lines---and, optionally, the | |
6239 | number of columns---to use for each page, when generating listings. | |
6240 | ||
6241 | If you do not use @code{.psize}, listings use a default line-count | |
6242 | of 60. You may omit the comma and @var{columns} specification; the | |
6243 | default width is 200 columns. | |
6244 | ||
6245 | @command{@value{AS}} generates formfeeds whenever the specified number of | |
6246 | lines is exceeded (or whenever you explicitly request one, using | |
6247 | @code{.eject}). | |
6248 | ||
6249 | If you specify @var{lines} as @code{0}, no formfeeds are generated save | |
6250 | those explicitly specified with @code{.eject}. | |
6251 | ||
6252 | @node Purgem | |
6253 | @section @code{.purgem @var{name}} | |
6254 | ||
6255 | @cindex @code{purgem} directive | |
6256 | Undefine the macro @var{name}, so that later uses of the string will not be | |
6257 | expanded. @xref{Macro}. | |
6258 | ||
6259 | @ifset ELF | |
6260 | @node PushSection | |
6261 | @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]} | |
6262 | ||
6263 | @cindex @code{pushsection} directive | |
6264 | @cindex Section Stack | |
6265 | This is one of the ELF section stack manipulation directives. The others are | |
6266 | @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}), | |
6267 | @code{.popsection} (@pxref{PopSection}), and @code{.previous} | |
6268 | (@pxref{Previous}). | |
6269 | ||
6270 | This directive pushes the current section (and subsection) onto the | |
6271 | top of the section stack, and then replaces the current section and | |
6272 | subsection with @code{name} and @code{subsection}. The optional | |
6273 | @code{flags}, @code{type} and @code{arguments} are treated the same | |
6274 | as in the @code{.section} (@pxref{Section}) directive. | |
6275 | @end ifset | |
6276 | ||
6277 | @node Quad | |
6278 | @section @code{.quad @var{bignums}} | |
6279 | ||
6280 | @cindex @code{quad} directive | |
6281 | @code{.quad} expects zero or more bignums, separated by commas. For | |
6282 | each bignum, it emits | |
6283 | @ifclear bignum-16 | |
6284 | an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a | |
6285 | warning message; and just takes the lowest order 8 bytes of the bignum. | |
6286 | @cindex eight-byte integer | |
6287 | @cindex integer, 8-byte | |
6288 | ||
6289 | The term ``quad'' comes from contexts in which a ``word'' is two bytes; | |
6290 | hence @emph{quad}-word for 8 bytes. | |
6291 | @end ifclear | |
6292 | @ifset bignum-16 | |
6293 | a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a | |
6294 | warning message; and just takes the lowest order 16 bytes of the bignum. | |
6295 | @cindex sixteen-byte integer | |
6296 | @cindex integer, 16-byte | |
6297 | @end ifset | |
6298 | ||
6299 | @node Reloc | |
6300 | @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]} | |
6301 | ||
6302 | @cindex @code{reloc} directive | |
6303 | Generate a relocation at @var{offset} of type @var{reloc_name} with value | |
6304 | @var{expression}. If @var{offset} is a number, the relocation is generated in | |
6305 | the current section. If @var{offset} is an expression that resolves to a | |
6306 | symbol plus offset, the relocation is generated in the given symbol's section. | |
6307 | @var{expression}, if present, must resolve to a symbol plus addend or to an | |
6308 | absolute value, but note that not all targets support an addend. e.g. ELF REL | |
6309 | targets such as i386 store an addend in the section contents rather than in the | |
6310 | relocation. This low level interface does not support addends stored in the | |
6311 | section. | |
6312 | ||
6313 | @node Rept | |
6314 | @section @code{.rept @var{count}} | |
6315 | ||
6316 | @cindex @code{rept} directive | |
6317 | Repeat the sequence of lines between the @code{.rept} directive and the next | |
6318 | @code{.endr} directive @var{count} times. | |
6319 | ||
6320 | For example, assembling | |
6321 | ||
6322 | @example | |
6323 | .rept 3 | |
6324 | .long 0 | |
6325 | .endr | |
6326 | @end example | |
6327 | ||
6328 | is equivalent to assembling | |
6329 | ||
6330 | @example | |
6331 | .long 0 | |
6332 | .long 0 | |
6333 | .long 0 | |
6334 | @end example | |
6335 | ||
6336 | A count of zero is allowed, but nothing is generated. Negative counts are not | |
6337 | allowed and if encountered will be treated as if they were zero. | |
6338 | ||
6339 | @node Sbttl | |
6340 | @section @code{.sbttl "@var{subheading}"} | |
6341 | ||
6342 | @cindex @code{sbttl} directive | |
6343 | @cindex subtitles for listings | |
6344 | @cindex listing control: subtitle | |
6345 | Use @var{subheading} as the title (third line, immediately after the | |
6346 | title line) when generating assembly listings. | |
6347 | ||
6348 | This directive affects subsequent pages, as well as the current page if | |
6349 | it appears within ten lines of the top of a page. | |
6350 | ||
6351 | @ifset COFF | |
6352 | @node Scl | |
6353 | @section @code{.scl @var{class}} | |
6354 | ||
6355 | @cindex @code{scl} directive | |
6356 | @cindex symbol storage class (COFF) | |
6357 | @cindex COFF symbol storage class | |
6358 | Set the storage-class value for a symbol. This directive may only be | |
6359 | used inside a @code{.def}/@code{.endef} pair. Storage class may flag | |
6360 | whether a symbol is static or external, or it may record further | |
6361 | symbolic debugging information. | |
6362 | @end ifset | |
6363 | ||
6364 | @ifset COFF-ELF | |
6365 | @node Section | |
6366 | @section @code{.section @var{name}} | |
6367 | ||
6368 | @cindex named section | |
6369 | Use the @code{.section} directive to assemble the following code into a section | |
6370 | named @var{name}. | |
6371 | ||
6372 | This directive is only supported for targets that actually support arbitrarily | |
6373 | named sections; on @code{a.out} targets, for example, it is not accepted, even | |
6374 | with a standard @code{a.out} section name. | |
6375 | ||
6376 | @ifset COFF | |
6377 | @ifset ELF | |
6378 | @c only print the extra heading if both COFF and ELF are set | |
6379 | @subheading COFF Version | |
6380 | @end ifset | |
6381 | ||
6382 | @cindex @code{section} directive (COFF version) | |
6383 | For COFF targets, the @code{.section} directive is used in one of the following | |
6384 | ways: | |
6385 | ||
6386 | @smallexample | |
6387 | .section @var{name}[, "@var{flags}"] | |
6388 | .section @var{name}[, @var{subsection}] | |
6389 | @end smallexample | |
6390 | ||
6391 | If the optional argument is quoted, it is taken as flags to use for the | |
6392 | section. Each flag is a single character. The following flags are recognized: | |
6393 | ||
6394 | @table @code | |
6395 | @item b | |
6396 | bss section (uninitialized data) | |
6397 | @item n | |
6398 | section is not loaded | |
6399 | @item w | |
6400 | writable section | |
6401 | @item d | |
6402 | data section | |
6403 | @item e | |
6404 | exclude section from linking | |
6405 | @item r | |
6406 | read-only section | |
6407 | @item x | |
6408 | executable section | |
6409 | @item s | |
6410 | shared section (meaningful for PE targets) | |
6411 | @item a | |
6412 | ignored. (For compatibility with the ELF version) | |
6413 | @item y | |
6414 | section is not readable (meaningful for PE targets) | |
6415 | @item 0-9 | |
6416 | single-digit power-of-two section alignment (GNU extension) | |
6417 | @end table | |
6418 | ||
6419 | If no flags are specified, the default flags depend upon the section name. If | |
6420 | the section name is not recognized, the default will be for the section to be | |
6421 | loaded and writable. Note the @code{n} and @code{w} flags remove attributes | |
6422 | from the section, rather than adding them, so if they are used on their own it | |
6423 | will be as if no flags had been specified at all. | |
6424 | ||
6425 | If the optional argument to the @code{.section} directive is not quoted, it is | |
6426 | taken as a subsection number (@pxref{Sub-Sections}). | |
6427 | @end ifset | |
6428 | ||
6429 | @ifset ELF | |
6430 | @ifset COFF | |
6431 | @c only print the extra heading if both COFF and ELF are set | |
6432 | @subheading ELF Version | |
6433 | @end ifset | |
6434 | ||
6435 | @cindex Section Stack | |
6436 | This is one of the ELF section stack manipulation directives. The others are | |
6437 | @code{.subsection} (@pxref{SubSection}), @code{.pushsection} | |
6438 | (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and | |
6439 | @code{.previous} (@pxref{Previous}). | |
6440 | ||
6441 | @cindex @code{section} directive (ELF version) | |
6442 | For ELF targets, the @code{.section} directive is used like this: | |
6443 | ||
6444 | @smallexample | |
6445 | .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]] | |
6446 | @end smallexample | |
6447 | ||
6448 | @anchor{Section Name Substitutions} | |
6449 | @kindex --sectname-subst | |
6450 | @cindex section name substitution | |
6451 | If the @samp{--sectname-subst} command-line option is provided, the @var{name} | |
6452 | argument may contain a substitution sequence. Only @code{%S} is supported | |
6453 | at the moment, and substitutes the current section name. For example: | |
6454 | ||
6455 | @smallexample | |
6456 | .macro exception_code | |
6457 | .section %S.exception | |
6458 | [exception code here] | |
6459 | .previous | |
6460 | .endm | |
6461 | ||
6462 | .text | |
6463 | [code] | |
6464 | exception_code | |
6465 | [...] | |
6466 | ||
6467 | .section .init | |
6468 | [init code] | |
6469 | exception_code | |
6470 | [...] | |
6471 | @end smallexample | |
6472 | ||
6473 | The two @code{exception_code} invocations above would create the | |
6474 | @code{.text.exception} and @code{.init.exception} sections respectively. | |
6475 | This is useful e.g. to discriminate between ancillary sections that are | |
6476 | tied to setup code to be discarded after use from ancillary sections that | |
6477 | need to stay resident without having to define multiple @code{exception_code} | |
6478 | macros just for that purpose. | |
6479 | ||
6480 | The optional @var{flags} argument is a quoted string which may contain any | |
6481 | combination of the following characters: | |
6482 | ||
6483 | @table @code | |
6484 | @item a | |
6485 | section is allocatable | |
6486 | @item d | |
6487 | section is a GNU_MBIND section | |
6488 | @item e | |
6489 | section is excluded from executable and shared library. | |
6490 | @item w | |
6491 | section is writable | |
6492 | @item x | |
6493 | section is executable | |
6494 | @item M | |
6495 | section is mergeable | |
6496 | @item S | |
6497 | section contains zero terminated strings | |
6498 | @item G | |
6499 | section is a member of a section group | |
6500 | @item T | |
6501 | section is used for thread-local-storage | |
6502 | @item ? | |
6503 | section is a member of the previously-current section's group, if any | |
6504 | @item @code{<number>} | |
6505 | a numeric value indicating the bits to be set in the ELF section header's flags | |
6506 | field. Note - if one or more of the alphabetic characters described above is | |
6507 | also included in the flags field, their bit values will be ORed into the | |
6508 | resulting value. | |
6509 | @item @code{<target specific>} | |
6510 | some targets extend this list with their own flag characters | |
6511 | @end table | |
6512 | ||
6513 | Note - once a section's flags have been set they cannot be changed. There are | |
6514 | a few exceptions to this rule however. Processor and application specific | |
6515 | flags can be added to an already defined section. The @code{.interp}, | |
6516 | @code{.strtab} and @code{.symtab} sections can have the allocate flag | |
6517 | (@code{a}) set after they are initially defined, and the @code{.note-GNU-stack} | |
6518 | section may have the executable (@code{x}) flag added. | |
6519 | ||
6520 | The optional @var{type} argument may contain one of the following constants: | |
6521 | ||
6522 | @table @code | |
6523 | @item @@progbits | |
6524 | section contains data | |
6525 | @item @@nobits | |
6526 | section does not contain data (i.e., section only occupies space) | |
6527 | @item @@note | |
6528 | section contains data which is used by things other than the program | |
6529 | @item @@init_array | |
6530 | section contains an array of pointers to init functions | |
6531 | @item @@fini_array | |
6532 | section contains an array of pointers to finish functions | |
6533 | @item @@preinit_array | |
6534 | section contains an array of pointers to pre-init functions | |
6535 | @item @@@code{<number>} | |
6536 | a numeric value to be set as the ELF section header's type field. | |
6537 | @item @@@code{<target specific>} | |
6538 | some targets extend this list with their own types | |
6539 | @end table | |
6540 | ||
6541 | Many targets only support the first three section types. The type may be | |
6542 | enclosed in double quotes if necessary. | |
6543 | ||
6544 | Note on targets where the @code{@@} character is the start of a comment (eg | |
6545 | ARM) then another character is used instead. For example the ARM port uses the | |
6546 | @code{%} character. | |
6547 | ||
6548 | Note - some sections, eg @code{.text} and @code{.data} are considered to be | |
6549 | special and have fixed types. Any attempt to declare them with a different | |
6550 | type will generate an error from the assembler. | |
6551 | ||
6552 | If @var{flags} contains the @code{M} symbol then the @var{type} argument must | |
6553 | be specified as well as an extra argument---@var{entsize}---like this: | |
6554 | ||
6555 | @smallexample | |
6556 | .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize} | |
6557 | @end smallexample | |
6558 | ||
6559 | Sections with the @code{M} flag but not @code{S} flag must contain fixed size | |
6560 | constants, each @var{entsize} octets long. Sections with both @code{M} and | |
6561 | @code{S} must contain zero terminated strings where each character is | |
6562 | @var{entsize} bytes long. The linker may remove duplicates within sections with | |
6563 | the same name, same entity size and same flags. @var{entsize} must be an | |
6564 | absolute expression. For sections with both @code{M} and @code{S}, a string | |
6565 | which is a suffix of a larger string is considered a duplicate. Thus | |
6566 | @code{"def"} will be merged with @code{"abcdef"}; A reference to the first | |
6567 | @code{"def"} will be changed to a reference to @code{"abcdef"+3}. | |
6568 | ||
6569 | If @var{flags} contains the @code{G} symbol then the @var{type} argument must | |
6570 | be present along with an additional field like this: | |
6571 | ||
6572 | @smallexample | |
6573 | .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}] | |
6574 | @end smallexample | |
6575 | ||
6576 | The @var{GroupName} field specifies the name of the section group to which this | |
6577 | particular section belongs. The optional linkage field can contain: | |
6578 | ||
6579 | @table @code | |
6580 | @item comdat | |
6581 | indicates that only one copy of this section should be retained | |
6582 | @item .gnu.linkonce | |
6583 | an alias for comdat | |
6584 | @end table | |
6585 | ||
6586 | Note: if both the @var{M} and @var{G} flags are present then the fields for | |
6587 | the Merge flag should come first, like this: | |
6588 | ||
6589 | @smallexample | |
6590 | .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}] | |
6591 | @end smallexample | |
6592 | ||
6593 | If @var{flags} contains the @code{?} symbol then it may not also contain the | |
6594 | @code{G} symbol and the @var{GroupName} or @var{linkage} fields should not be | |
6595 | present. Instead, @code{?} says to consider the section that's current before | |
6596 | this directive. If that section used @code{G}, then the new section will use | |
6597 | @code{G} with those same @var{GroupName} and @var{linkage} fields implicitly. | |
6598 | If not, then the @code{?} symbol has no effect. | |
6599 | ||
6600 | If no flags are specified, the default flags depend upon the section name. If | |
6601 | the section name is not recognized, the default will be for the section to have | |
6602 | none of the above flags: it will not be allocated in memory, nor writable, nor | |
6603 | executable. The section will contain data. | |
6604 | ||
6605 | For ELF targets, the assembler supports another type of @code{.section} | |
6606 | directive for compatibility with the Solaris assembler: | |
6607 | ||
6608 | @smallexample | |
6609 | .section "@var{name}"[, @var{flags}...] | |
6610 | @end smallexample | |
6611 | ||
6612 | Note that the section name is quoted. There may be a sequence of comma | |
6613 | separated flags: | |
6614 | ||
6615 | @table @code | |
6616 | @item #alloc | |
6617 | section is allocatable | |
6618 | @item #write | |
6619 | section is writable | |
6620 | @item #execinstr | |
6621 | section is executable | |
6622 | @item #exclude | |
6623 | section is excluded from executable and shared library. | |
6624 | @item #tls | |
6625 | section is used for thread local storage | |
6626 | @end table | |
6627 | ||
6628 | This directive replaces the current section and subsection. See the | |
6629 | contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for | |
6630 | some examples of how this directive and the other section stack directives | |
6631 | work. | |
6632 | @end ifset | |
6633 | @end ifset | |
6634 | ||
6635 | @node Set | |
6636 | @section @code{.set @var{symbol}, @var{expression}} | |
6637 | ||
6638 | @cindex @code{set} directive | |
6639 | @cindex symbol value, setting | |
6640 | Set the value of @var{symbol} to @var{expression}. This | |
6641 | changes @var{symbol}'s value and type to conform to | |
6642 | @var{expression}. If @var{symbol} was flagged as external, it remains | |
6643 | flagged (@pxref{Symbol Attributes}). | |
6644 | ||
6645 | You may @code{.set} a symbol many times in the same assembly provided that the | |
6646 | values given to the symbol are constants. Values that are based on expressions | |
6647 | involving other symbols are allowed, but some targets may restrict this to only | |
6648 | being done once per assembly. This is because those targets do not set the | |
6649 | addresses of symbols at assembly time, but rather delay the assignment until a | |
6650 | final link is performed. This allows the linker a chance to change the code in | |
6651 | the files, changing the location of, and the relative distance between, various | |
6652 | different symbols. | |
6653 | ||
6654 | If you @code{.set} a global symbol, the value stored in the object | |
6655 | file is the last value stored into it. | |
6656 | ||
6657 | @ifset Z80 | |
6658 | On Z80 @code{set} is a real instruction, use | |
6659 | @samp{@var{symbol} defl @var{expression}} instead. | |
6660 | @end ifset | |
6661 | ||
6662 | @node Short | |
6663 | @section @code{.short @var{expressions}} | |
6664 | ||
6665 | @cindex @code{short} directive | |
6666 | @ifset GENERIC | |
6667 | @code{.short} is normally the same as @samp{.word}. | |
6668 | @xref{Word,,@code{.word}}. | |
6669 | ||
6670 | In some configurations, however, @code{.short} and @code{.word} generate | |
6671 | numbers of different lengths. @xref{Machine Dependencies}. | |
6672 | @end ifset | |
6673 | @ifclear GENERIC | |
6674 | @ifset W16 | |
6675 | @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}. | |
6676 | @end ifset | |
6677 | @ifset W32 | |
6678 | This expects zero or more @var{expressions}, and emits | |
6679 | a 16 bit number for each. | |
6680 | @end ifset | |
6681 | @end ifclear | |
6682 | ||
6683 | @node Single | |
6684 | @section @code{.single @var{flonums}} | |
6685 | ||
6686 | @cindex @code{single} directive | |
6687 | @cindex floating point numbers (single) | |
6688 | This directive assembles zero or more flonums, separated by commas. It | |
6689 | has the same effect as @code{.float}. | |
6690 | @ifset GENERIC | |
6691 | The exact kind of floating point numbers emitted depends on how | |
6692 | @command{@value{AS}} is configured. @xref{Machine Dependencies}. | |
6693 | @end ifset | |
6694 | @ifclear GENERIC | |
6695 | @ifset IEEEFLOAT | |
6696 | On the @value{TARGET} family, @code{.single} emits 32-bit floating point | |
6697 | numbers in @sc{ieee} format. | |
6698 | @end ifset | |
6699 | @end ifclear | |
6700 | ||
6701 | @ifset COFF-ELF | |
6702 | @node Size | |
6703 | @section @code{.size} | |
6704 | ||
6705 | This directive is used to set the size associated with a symbol. | |
6706 | ||
6707 | @ifset COFF | |
6708 | @ifset ELF | |
6709 | @c only print the extra heading if both COFF and ELF are set | |
6710 | @subheading COFF Version | |
6711 | @end ifset | |
6712 | ||
6713 | @cindex @code{size} directive (COFF version) | |
6714 | For COFF targets, the @code{.size} directive is only permitted inside | |
6715 | @code{.def}/@code{.endef} pairs. It is used like this: | |
6716 | ||
6717 | @smallexample | |
6718 | .size @var{expression} | |
6719 | @end smallexample | |
6720 | ||
6721 | @end ifset | |
6722 | ||
6723 | @ifset ELF | |
6724 | @ifset COFF | |
6725 | @c only print the extra heading if both COFF and ELF are set | |
6726 | @subheading ELF Version | |
6727 | @end ifset | |
6728 | ||
6729 | @cindex @code{size} directive (ELF version) | |
6730 | For ELF targets, the @code{.size} directive is used like this: | |
6731 | ||
6732 | @smallexample | |
6733 | .size @var{name} , @var{expression} | |
6734 | @end smallexample | |
6735 | ||
6736 | This directive sets the size associated with a symbol @var{name}. | |
6737 | The size in bytes is computed from @var{expression} which can make use of label | |
6738 | arithmetic. This directive is typically used to set the size of function | |
6739 | symbols. | |
6740 | @end ifset | |
6741 | @end ifset | |
6742 | ||
6743 | @ifclear no-space-dir | |
6744 | @node Skip | |
6745 | @section @code{.skip @var{size} [,@var{fill}]} | |
6746 | ||
6747 | @cindex @code{skip} directive | |
6748 | @cindex filling memory | |
6749 | This directive emits @var{size} bytes, each of value @var{fill}. Both | |
6750 | @var{size} and @var{fill} are absolute expressions. If the comma and | |
6751 | @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as | |
6752 | @samp{.space}. | |
6753 | @end ifclear | |
6754 | ||
6755 | @node Sleb128 | |
6756 | @section @code{.sleb128 @var{expressions}} | |
6757 | ||
6758 | @cindex @code{sleb128} directive | |
6759 | @var{sleb128} stands for ``signed little endian base 128.'' This is a | |
6760 | compact, variable length representation of numbers used by the DWARF | |
6761 | symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}. | |
6762 | ||
6763 | @ifclear no-space-dir | |
6764 | @node Space | |
6765 | @section @code{.space @var{size} [,@var{fill}]} | |
6766 | ||
6767 | @cindex @code{space} directive | |
6768 | @cindex filling memory | |
6769 | This directive emits @var{size} bytes, each of value @var{fill}. Both | |
6770 | @var{size} and @var{fill} are absolute expressions. If the comma | |
6771 | and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same | |
6772 | as @samp{.skip}. | |
6773 | ||
6774 | @ifset HPPA | |
6775 | @quotation | |
6776 | @emph{Warning:} @code{.space} has a completely different meaning for HPPA | |
6777 | targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800 | |
6778 | Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the | |
6779 | @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives}, | |
6780 | for a summary. | |
6781 | @end quotation | |
6782 | @end ifset | |
6783 | @end ifclear | |
6784 | ||
6785 | @ifset have-stabs | |
6786 | @node Stab | |
6787 | @section @code{.stabd, .stabn, .stabs} | |
6788 | ||
6789 | @cindex symbolic debuggers, information for | |
6790 | @cindex @code{stab@var{x}} directives | |
6791 | There are three directives that begin @samp{.stab}. | |
6792 | All emit symbols (@pxref{Symbols}), for use by symbolic debuggers. | |
6793 | The symbols are not entered in the @command{@value{AS}} hash table: they | |
6794 | cannot be referenced elsewhere in the source file. | |
6795 | Up to five fields are required: | |
6796 | ||
6797 | @table @var | |
6798 | @item string | |
6799 | This is the symbol's name. It may contain any character except | |
6800 | @samp{\000}, so is more general than ordinary symbol names. Some | |
6801 | debuggers used to code arbitrarily complex structures into symbol names | |
6802 | using this field. | |
6803 | ||
6804 | @item type | |
6805 | An absolute expression. The symbol's type is set to the low 8 bits of | |
6806 | this expression. Any bit pattern is permitted, but @code{@value{LD}} | |
6807 | and debuggers choke on silly bit patterns. | |
6808 | ||
6809 | @item other | |
6810 | An absolute expression. The symbol's ``other'' attribute is set to the | |
6811 | low 8 bits of this expression. | |
6812 | ||
6813 | @item desc | |
6814 | An absolute expression. The symbol's descriptor is set to the low 16 | |
6815 | bits of this expression. | |
6816 | ||
6817 | @item value | |
6818 | An absolute expression which becomes the symbol's value. | |
6819 | @end table | |
6820 | ||
6821 | If a warning is detected while reading a @code{.stabd}, @code{.stabn}, | |
6822 | or @code{.stabs} statement, the symbol has probably already been created; | |
6823 | you get a half-formed symbol in your object file. This is | |
6824 | compatible with earlier assemblers! | |
6825 | ||
6826 | @table @code | |
6827 | @cindex @code{stabd} directive | |
6828 | @item .stabd @var{type} , @var{other} , @var{desc} | |
6829 | ||
6830 | The ``name'' of the symbol generated is not even an empty string. | |
6831 | It is a null pointer, for compatibility. Older assemblers used a | |
6832 | null pointer so they didn't waste space in object files with empty | |
6833 | strings. | |
6834 | ||
6835 | The symbol's value is set to the location counter, | |
6836 | relocatably. When your program is linked, the value of this symbol | |
6837 | is the address of the location counter when the @code{.stabd} was | |
6838 | assembled. | |
6839 | ||
6840 | @cindex @code{stabn} directive | |
6841 | @item .stabn @var{type} , @var{other} , @var{desc} , @var{value} | |
6842 | The name of the symbol is set to the empty string @code{""}. | |
6843 | ||
6844 | @cindex @code{stabs} directive | |
6845 | @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value} | |
6846 | All five fields are specified. | |
6847 | @end table | |
6848 | @end ifset | |
6849 | @c end have-stabs | |
6850 | ||
6851 | @node String | |
6852 | @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16} | |
6853 | "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}" | |
6854 | ||
6855 | @cindex string, copying to object file | |
6856 | @cindex string8, copying to object file | |
6857 | @cindex string16, copying to object file | |
6858 | @cindex string32, copying to object file | |
6859 | @cindex string64, copying to object file | |
6860 | @cindex @code{string} directive | |
6861 | @cindex @code{string8} directive | |
6862 | @cindex @code{string16} directive | |
6863 | @cindex @code{string32} directive | |
6864 | @cindex @code{string64} directive | |
6865 | ||
6866 | Copy the characters in @var{str} to the object file. You may specify more than | |
6867 | one string to copy, separated by commas. Unless otherwise specified for a | |
6868 | particular machine, the assembler marks the end of each string with a 0 byte. | |
6869 | You can use any of the escape sequences described in @ref{Strings,,Strings}. | |
6870 | ||
6871 | The variants @code{string16}, @code{string32} and @code{string64} differ from | |
6872 | the @code{string} pseudo opcode in that each 8-bit character from @var{str} is | |
6873 | copied and expanded to 16, 32 or 64 bits respectively. The expanded characters | |
6874 | are stored in target endianness byte order. | |
6875 | ||
6876 | Example: | |
6877 | @smallexample | |
6878 | .string32 "BYE" | |
6879 | expands to: | |
6880 | .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */ | |
6881 | .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */ | |
6882 | @end smallexample | |
6883 | ||
6884 | ||
6885 | @node Struct | |
6886 | @section @code{.struct @var{expression}} | |
6887 | ||
6888 | @cindex @code{struct} directive | |
6889 | Switch to the absolute section, and set the section offset to @var{expression}, | |
6890 | which must be an absolute expression. You might use this as follows: | |
6891 | @smallexample | |
6892 | .struct 0 | |
6893 | field1: | |
6894 | .struct field1 + 4 | |
6895 | field2: | |
6896 | .struct field2 + 4 | |
6897 | field3: | |
6898 | @end smallexample | |
6899 | This would define the symbol @code{field1} to have the value 0, the symbol | |
6900 | @code{field2} to have the value 4, and the symbol @code{field3} to have the | |
6901 | value 8. Assembly would be left in the absolute section, and you would need to | |
6902 | use a @code{.section} directive of some sort to change to some other section | |
6903 | before further assembly. | |
6904 | ||
6905 | @ifset ELF | |
6906 | @node SubSection | |
6907 | @section @code{.subsection @var{name}} | |
6908 | ||
6909 | @cindex @code{subsection} directive | |
6910 | @cindex Section Stack | |
6911 | This is one of the ELF section stack manipulation directives. The others are | |
6912 | @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}), | |
6913 | @code{.popsection} (@pxref{PopSection}), and @code{.previous} | |
6914 | (@pxref{Previous}). | |
6915 | ||
6916 | This directive replaces the current subsection with @code{name}. The current | |
6917 | section is not changed. The replaced subsection is put onto the section stack | |
6918 | in place of the then current top of stack subsection. | |
6919 | @end ifset | |
6920 | ||
6921 | @ifset ELF | |
6922 | @node Symver | |
6923 | @section @code{.symver} | |
6924 | @cindex @code{symver} directive | |
6925 | @cindex symbol versioning | |
6926 | @cindex versions of symbols | |
6927 | Use the @code{.symver} directive to bind symbols to specific version nodes | |
6928 | within a source file. This is only supported on ELF platforms, and is | |
6929 | typically used when assembling files to be linked into a shared library. | |
6930 | There are cases where it may make sense to use this in objects to be bound | |
6931 | into an application itself so as to override a versioned symbol from a | |
6932 | shared library. | |
6933 | ||
6934 | For ELF targets, the @code{.symver} directive can be used like this: | |
6935 | @smallexample | |
6936 | .symver @var{name}, @var{name2@@nodename} | |
6937 | @end smallexample | |
6938 | If the symbol @var{name} is defined within the file | |
6939 | being assembled, the @code{.symver} directive effectively creates a symbol | |
6940 | alias with the name @var{name2@@nodename}, and in fact the main reason that we | |
6941 | just don't try and create a regular alias is that the @var{@@} character isn't | |
6942 | permitted in symbol names. The @var{name2} part of the name is the actual name | |
6943 | of the symbol by which it will be externally referenced. The name @var{name} | |
6944 | itself is merely a name of convenience that is used so that it is possible to | |
6945 | have definitions for multiple versions of a function within a single source | |
6946 | file, and so that the compiler can unambiguously know which version of a | |
6947 | function is being mentioned. The @var{nodename} portion of the alias should be | |
6948 | the name of a node specified in the version script supplied to the linker when | |
6949 | building a shared library. If you are attempting to override a versioned | |
6950 | symbol from a shared library, then @var{nodename} should correspond to the | |
6951 | nodename of the symbol you are trying to override. | |
6952 | ||
6953 | If the symbol @var{name} is not defined within the file being assembled, all | |
6954 | references to @var{name} will be changed to @var{name2@@nodename}. If no | |
6955 | reference to @var{name} is made, @var{name2@@nodename} will be removed from the | |
6956 | symbol table. | |
6957 | ||
6958 | Another usage of the @code{.symver} directive is: | |
6959 | @smallexample | |
6960 | .symver @var{name}, @var{name2@@@@nodename} | |
6961 | @end smallexample | |
6962 | In this case, the symbol @var{name} must exist and be defined within | |
6963 | the file being assembled. It is similar to @var{name2@@nodename}. The | |
6964 | difference is @var{name2@@@@nodename} will also be used to resolve | |
6965 | references to @var{name2} by the linker. | |
6966 | ||
6967 | The third usage of the @code{.symver} directive is: | |
6968 | @smallexample | |
6969 | .symver @var{name}, @var{name2@@@@@@nodename} | |
6970 | @end smallexample | |
6971 | When @var{name} is not defined within the | |
6972 | file being assembled, it is treated as @var{name2@@nodename}. When | |
6973 | @var{name} is defined within the file being assembled, the symbol | |
6974 | name, @var{name}, will be changed to @var{name2@@@@nodename}. | |
6975 | @end ifset | |
6976 | ||
6977 | @ifset COFF | |
6978 | @node Tag | |
6979 | @section @code{.tag @var{structname}} | |
6980 | ||
6981 | @cindex COFF structure debugging | |
6982 | @cindex structure debugging, COFF | |
6983 | @cindex @code{tag} directive | |
6984 | This directive is generated by compilers to include auxiliary debugging | |
6985 | information in the symbol table. It is only permitted inside | |
6986 | @code{.def}/@code{.endef} pairs. Tags are used to link structure | |
6987 | definitions in the symbol table with instances of those structures. | |
6988 | @end ifset | |
6989 | ||
6990 | @node Text | |
6991 | @section @code{.text @var{subsection}} | |
6992 | ||
6993 | @cindex @code{text} directive | |
6994 | Tells @command{@value{AS}} to assemble the following statements onto the end of | |
6995 | the text subsection numbered @var{subsection}, which is an absolute | |
6996 | expression. If @var{subsection} is omitted, subsection number zero | |
6997 | is used. | |
6998 | ||
6999 | @node Title | |
7000 | @section @code{.title "@var{heading}"} | |
7001 | ||
7002 | @cindex @code{title} directive | |
7003 | @cindex listing control: title line | |
7004 | Use @var{heading} as the title (second line, immediately after the | |
7005 | source file name and pagenumber) when generating assembly listings. | |
7006 | ||
7007 | This directive affects subsequent pages, as well as the current page if | |
7008 | it appears within ten lines of the top of a page. | |
7009 | ||
7010 | @ifset COFF-ELF | |
7011 | @node Type | |
7012 | @section @code{.type} | |
7013 | ||
7014 | This directive is used to set the type of a symbol. | |
7015 | ||
7016 | @ifset COFF | |
7017 | @ifset ELF | |
7018 | @c only print the extra heading if both COFF and ELF are set | |
7019 | @subheading COFF Version | |
7020 | @end ifset | |
7021 | ||
7022 | @cindex COFF symbol type | |
7023 | @cindex symbol type, COFF | |
7024 | @cindex @code{type} directive (COFF version) | |
7025 | For COFF targets, this directive is permitted only within | |
7026 | @code{.def}/@code{.endef} pairs. It is used like this: | |
7027 | ||
7028 | @smallexample | |
7029 | .type @var{int} | |
7030 | @end smallexample | |
7031 | ||
7032 | This records the integer @var{int} as the type attribute of a symbol table | |
7033 | entry. | |
7034 | ||
7035 | @end ifset | |
7036 | ||
7037 | @ifset ELF | |
7038 | @ifset COFF | |
7039 | @c only print the extra heading if both COFF and ELF are set | |
7040 | @subheading ELF Version | |
7041 | @end ifset | |
7042 | ||
7043 | @cindex ELF symbol type | |
7044 | @cindex symbol type, ELF | |
7045 | @cindex @code{type} directive (ELF version) | |
7046 | For ELF targets, the @code{.type} directive is used like this: | |
7047 | ||
7048 | @smallexample | |
7049 | .type @var{name} , @var{type description} | |
7050 | @end smallexample | |
7051 | ||
7052 | This sets the type of symbol @var{name} to be either a | |
7053 | function symbol or an object symbol. There are five different syntaxes | |
7054 | supported for the @var{type description} field, in order to provide | |
7055 | compatibility with various other assemblers. | |
7056 | ||
7057 | Because some of the characters used in these syntaxes (such as @samp{@@} and | |
7058 | @samp{#}) are comment characters for some architectures, some of the syntaxes | |
7059 | below do not work on all architectures. The first variant will be accepted by | |
7060 | the GNU assembler on all architectures so that variant should be used for | |
7061 | maximum portability, if you do not need to assemble your code with other | |
7062 | assemblers. | |
7063 | ||
7064 | The syntaxes supported are: | |
7065 | ||
7066 | @smallexample | |
7067 | .type <name> STT_<TYPE_IN_UPPER_CASE> | |
7068 | .type <name>,#<type> | |
7069 | .type <name>,@@<type> | |
7070 | .type <name>,%<type> | |
7071 | .type <name>,"<type>" | |
7072 | @end smallexample | |
7073 | ||
7074 | The types supported are: | |
7075 | ||
7076 | @table @gcctabopt | |
7077 | @item STT_FUNC | |
7078 | @itemx function | |
7079 | Mark the symbol as being a function name. | |
7080 | ||
7081 | @item STT_GNU_IFUNC | |
7082 | @itemx gnu_indirect_function | |
7083 | Mark the symbol as an indirect function when evaluated during reloc | |
7084 | processing. (This is only supported on assemblers targeting GNU systems). | |
7085 | ||
7086 | @item STT_OBJECT | |
7087 | @itemx object | |
7088 | Mark the symbol as being a data object. | |
7089 | ||
7090 | @item STT_TLS | |
7091 | @itemx tls_object | |
7092 | Mark the symbol as being a thread-local data object. | |
7093 | ||
7094 | @item STT_COMMON | |
7095 | @itemx common | |
7096 | Mark the symbol as being a common data object. | |
7097 | ||
7098 | @item STT_NOTYPE | |
7099 | @itemx notype | |
7100 | Does not mark the symbol in any way. It is supported just for completeness. | |
7101 | ||
7102 | @item gnu_unique_object | |
7103 | Marks the symbol as being a globally unique data object. The dynamic linker | |
7104 | will make sure that in the entire process there is just one symbol with this | |
7105 | name and type in use. (This is only supported on assemblers targeting GNU | |
7106 | systems). | |
7107 | ||
7108 | @end table | |
7109 | ||
7110 | Note: Some targets support extra types in addition to those listed above. | |
7111 | ||
7112 | @end ifset | |
7113 | @end ifset | |
7114 | ||
7115 | @node Uleb128 | |
7116 | @section @code{.uleb128 @var{expressions}} | |
7117 | ||
7118 | @cindex @code{uleb128} directive | |
7119 | @var{uleb128} stands for ``unsigned little endian base 128.'' This is a | |
7120 | compact, variable length representation of numbers used by the DWARF | |
7121 | symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}. | |
7122 | ||
7123 | @ifset COFF | |
7124 | @node Val | |
7125 | @section @code{.val @var{addr}} | |
7126 | ||
7127 | @cindex @code{val} directive | |
7128 | @cindex COFF value attribute | |
7129 | @cindex value attribute, COFF | |
7130 | This directive, permitted only within @code{.def}/@code{.endef} pairs, | |
7131 | records the address @var{addr} as the value attribute of a symbol table | |
7132 | entry. | |
7133 | @end ifset | |
7134 | ||
7135 | @ifset ELF | |
7136 | @node Version | |
7137 | @section @code{.version "@var{string}"} | |
7138 | ||
7139 | @cindex @code{version} directive | |
7140 | This directive creates a @code{.note} section and places into it an ELF | |
7141 | formatted note of type NT_VERSION. The note's name is set to @code{string}. | |
7142 | @end ifset | |
7143 | ||
7144 | @ifset ELF | |
7145 | @node VTableEntry | |
7146 | @section @code{.vtable_entry @var{table}, @var{offset}} | |
7147 | ||
7148 | @cindex @code{vtable_entry} directive | |
7149 | This directive finds or creates a symbol @code{table} and creates a | |
7150 | @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}. | |
7151 | ||
7152 | @node VTableInherit | |
7153 | @section @code{.vtable_inherit @var{child}, @var{parent}} | |
7154 | ||
7155 | @cindex @code{vtable_inherit} directive | |
7156 | This directive finds the symbol @code{child} and finds or creates the symbol | |
7157 | @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the | |
7158 | parent whose addend is the value of the child symbol. As a special case the | |
7159 | parent name of @code{0} is treated as referring to the @code{*ABS*} section. | |
7160 | @end ifset | |
7161 | ||
7162 | @node Warning | |
7163 | @section @code{.warning "@var{string}"} | |
7164 | @cindex warning directive | |
7165 | Similar to the directive @code{.error} | |
7166 | (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning. | |
7167 | ||
7168 | @node Weak | |
7169 | @section @code{.weak @var{names}} | |
7170 | ||
7171 | @cindex @code{weak} directive | |
7172 | This directive sets the weak attribute on the comma separated list of symbol | |
7173 | @code{names}. If the symbols do not already exist, they will be created. | |
7174 | ||
7175 | On COFF targets other than PE, weak symbols are a GNU extension. This | |
7176 | directive sets the weak attribute on the comma separated list of symbol | |
7177 | @code{names}. If the symbols do not already exist, they will be created. | |
7178 | ||
7179 | On the PE target, weak symbols are supported natively as weak aliases. | |
7180 | When a weak symbol is created that is not an alias, GAS creates an | |
7181 | alternate symbol to hold the default value. | |
7182 | ||
7183 | @node Weakref | |
7184 | @section @code{.weakref @var{alias}, @var{target}} | |
7185 | ||
7186 | @cindex @code{weakref} directive | |
7187 | This directive creates an alias to the target symbol that enables the symbol to | |
7188 | be referenced with weak-symbol semantics, but without actually making it weak. | |
7189 | If direct references or definitions of the symbol are present, then the symbol | |
7190 | will not be weak, but if all references to it are through weak references, the | |
7191 | symbol will be marked as weak in the symbol table. | |
7192 | ||
7193 | The effect is equivalent to moving all references to the alias to a separate | |
7194 | assembly source file, renaming the alias to the symbol in it, declaring the | |
7195 | symbol as weak there, and running a reloadable link to merge the object files | |
7196 | resulting from the assembly of the new source file and the old source file that | |
7197 | had the references to the alias removed. | |
7198 | ||
7199 | The alias itself never makes to the symbol table, and is entirely handled | |
7200 | within the assembler. | |
7201 | ||
7202 | @node Word | |
7203 | @section @code{.word @var{expressions}} | |
7204 | ||
7205 | @cindex @code{word} directive | |
7206 | This directive expects zero or more @var{expressions}, of any section, | |
7207 | separated by commas. | |
7208 | @ifclear GENERIC | |
7209 | @ifset W32 | |
7210 | For each expression, @command{@value{AS}} emits a 32-bit number. | |
7211 | @end ifset | |
7212 | @ifset W16 | |
7213 | For each expression, @command{@value{AS}} emits a 16-bit number. | |
7214 | @end ifset | |
7215 | @end ifclear | |
7216 | @ifset GENERIC | |
7217 | ||
7218 | The size of the number emitted, and its byte order, | |
7219 | depend on what target computer the assembly is for. | |
7220 | @end ifset | |
7221 | ||
7222 | @c on sparc the "special treatment to support compilers" doesn't | |
7223 | @c happen---32-bit addressability, period; no long/short jumps. | |
7224 | @ifset DIFF-TBL-KLUGE | |
7225 | @cindex difference tables altered | |
7226 | @cindex altered difference tables | |
7227 | @quotation | |
7228 | @emph{Warning: Special Treatment to support Compilers} | |
7229 | @end quotation | |
7230 | ||
7231 | @ifset GENERIC | |
7232 | Machines with a 32-bit address space, but that do less than 32-bit | |
7233 | addressing, require the following special treatment. If the machine of | |
7234 | interest to you does 32-bit addressing (or doesn't require it; | |
7235 | @pxref{Machine Dependencies}), you can ignore this issue. | |
7236 | ||
7237 | @end ifset | |
7238 | In order to assemble compiler output into something that works, | |
7239 | @command{@value{AS}} occasionally does strange things to @samp{.word} directives. | |
7240 | Directives of the form @samp{.word sym1-sym2} are often emitted by | |
7241 | compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a | |
7242 | directive of the form @samp{.word sym1-sym2}, and the difference between | |
7243 | @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}} | |
7244 | creates a @dfn{secondary jump table}, immediately before the next label. | |
7245 | This secondary jump table is preceded by a short-jump to the | |
7246 | first byte after the secondary table. This short-jump prevents the flow | |
7247 | of control from accidentally falling into the new table. Inside the | |
7248 | table is a long-jump to @code{sym2}. The original @samp{.word} | |
7249 | contains @code{sym1} minus the address of the long-jump to | |
7250 | @code{sym2}. | |
7251 | ||
7252 | If there were several occurrences of @samp{.word sym1-sym2} before the | |
7253 | secondary jump table, all of them are adjusted. If there was a | |
7254 | @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a | |
7255 | long-jump to @code{sym4} is included in the secondary jump table, | |
7256 | and the @code{.word} directives are adjusted to contain @code{sym3} | |
7257 | minus the address of the long-jump to @code{sym4}; and so on, for as many | |
7258 | entries in the original jump table as necessary. | |
7259 | ||
7260 | @ifset INTERNALS | |
7261 | @emph{This feature may be disabled by compiling @command{@value{AS}} with the | |
7262 | @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse | |
7263 | assembly language programmers. | |
7264 | @end ifset | |
7265 | @end ifset | |
7266 | @c end DIFF-TBL-KLUGE | |
7267 | ||
7268 | @ifclear no-space-dir | |
7269 | @node Zero | |
7270 | @section @code{.zero @var{size}} | |
7271 | ||
7272 | @cindex @code{zero} directive | |
7273 | @cindex filling memory with zero bytes | |
7274 | This directive emits @var{size} 0-valued bytes. @var{size} must be an absolute | |
7275 | expression. This directive is actually an alias for the @samp{.skip} directive | |
7276 | so in can take an optional second argument of the value to store in the bytes | |
7277 | instead of zero. Using @samp{.zero} in this way would be confusing however. | |
7278 | @end ifclear | |
7279 | ||
7280 | @ifset ELF | |
7281 | @node 2byte | |
7282 | @section @code{.2byte @var{expression} [, @var{expression}]*} | |
7283 | @cindex @code{2byte} directive | |
7284 | @cindex two-byte integer | |
7285 | @cindex integer, 2-byte | |
7286 | ||
7287 | This directive expects zero or more expressions, separated by commas. If there | |
7288 | are no expressions then the directive does nothing. Otherwise each expression | |
7289 | is evaluated in turn and placed in the next two bytes of the current output | |
7290 | section, using the endian model of the target. If an expression will not fit | |
7291 | in two bytes, a warning message is displayed and the least significant two | |
7292 | bytes of the expression's value are used. If an expression cannot be evaluated | |
7293 | at assembly time then relocations will be generated in order to compute the | |
7294 | value at link time. | |
7295 | ||
7296 | This directive does not apply any alignment before or after inserting the | |
7297 | values. As a result of this, if relocations are generated, they may be | |
7298 | different from those used for inserting values with a guaranteed alignment. | |
7299 | ||
7300 | This directive is only available for ELF targets, | |
7301 | ||
7302 | @node 4byte | |
7303 | @section @code{.4byte @var{expression} [, @var{expression}]*} | |
7304 | @cindex @code{4byte} directive | |
7305 | @cindex four-byte integer | |
7306 | @cindex integer, 4-byte | |
7307 | ||
7308 | Like the @option{.2byte} directive, except that it inserts unaligned, four byte | |
7309 | long values into the output. | |
7310 | ||
7311 | @node 8byte | |
7312 | @section @code{.8byte @var{expression} [, @var{expression}]*} | |
7313 | @cindex @code{8byte} directive | |
7314 | @cindex eight-byte integer | |
7315 | @cindex integer, 8-byte | |
7316 | ||
7317 | Like the @option{.2byte} directive, except that it inserts unaligned, eight | |
7318 | byte long bignum values into the output. | |
7319 | ||
7320 | @end ifset | |
7321 | ||
7322 | @node Deprecated | |
7323 | @section Deprecated Directives | |
7324 | ||
7325 | @cindex deprecated directives | |
7326 | @cindex obsolescent directives | |
7327 | One day these directives won't work. | |
7328 | They are included for compatibility with older assemblers. | |
7329 | @table @t | |
7330 | @item .abort | |
7331 | @item .line | |
7332 | @end table | |
7333 | ||
7334 | @ifset ELF | |
7335 | @node Object Attributes | |
7336 | @chapter Object Attributes | |
7337 | @cindex object attributes | |
7338 | ||
7339 | @command{@value{AS}} assembles source files written for a specific architecture | |
7340 | into object files for that architecture. But not all object files are alike. | |
7341 | Many architectures support incompatible variations. For instance, floating | |
7342 | point arguments might be passed in floating point registers if the object file | |
7343 | requires hardware floating point support---or floating point arguments might be | |
7344 | passed in integer registers if the object file supports processors with no | |
7345 | hardware floating point unit. Or, if two objects are built for different | |
7346 | generations of the same architecture, the combination may require the | |
7347 | newer generation at run-time. | |
7348 | ||
7349 | This information is useful during and after linking. At link time, | |
7350 | @command{@value{LD}} can warn about incompatible object files. After link | |
7351 | time, tools like @command{gdb} can use it to process the linked file | |
7352 | correctly. | |
7353 | ||
7354 | Compatibility information is recorded as a series of object attributes. Each | |
7355 | attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a | |
7356 | string, and indicates who sets the meaning of the tag. The tag is an integer, | |
7357 | and indicates what property the attribute describes. The value may be a string | |
7358 | or an integer, and indicates how the property affects this object. Missing | |
7359 | attributes are the same as attributes with a zero value or empty string value. | |
7360 | ||
7361 | Object attributes were developed as part of the ABI for the ARM Architecture. | |
7362 | The file format is documented in @cite{ELF for the ARM Architecture}. | |
7363 | ||
7364 | @menu | |
7365 | * GNU Object Attributes:: @sc{gnu} Object Attributes | |
7366 | * Defining New Object Attributes:: Defining New Object Attributes | |
7367 | @end menu | |
7368 | ||
7369 | @node GNU Object Attributes | |
7370 | @section @sc{gnu} Object Attributes | |
7371 | ||
7372 | The @code{.gnu_attribute} directive records an object attribute | |
7373 | with vendor @samp{gnu}. | |
7374 | ||
7375 | Except for @samp{Tag_compatibility}, which has both an integer and a string for | |
7376 | its value, @sc{gnu} attributes have a string value if the tag number is odd and | |
7377 | an integer value if the tag number is even. The second bit (@code{@var{tag} & | |
7378 | 2} is set for architecture-independent attributes and clear for | |
7379 | architecture-dependent ones. | |
7380 | ||
7381 | @subsection Common @sc{gnu} attributes | |
7382 | ||
7383 | These attributes are valid on all architectures. | |
7384 | ||
7385 | @table @r | |
7386 | @item Tag_compatibility (32) | |
7387 | The compatibility attribute takes an integer flag value and a vendor name. If | |
7388 | the flag value is 0, the file is compatible with other toolchains. If it is 1, | |
7389 | then the file is only compatible with the named toolchain. If it is greater | |
7390 | than 1, the file can only be processed by other toolchains under some private | |
7391 | arrangement indicated by the flag value and the vendor name. | |
7392 | @end table | |
7393 | ||
7394 | @subsection MIPS Attributes | |
7395 | ||
7396 | @table @r | |
7397 | @item Tag_GNU_MIPS_ABI_FP (4) | |
7398 | The floating-point ABI used by this object file. The value will be: | |
7399 | ||
7400 | @itemize @bullet | |
7401 | @item | |
7402 | 0 for files not affected by the floating-point ABI. | |
7403 | @item | |
7404 | 1 for files using the hardware floating-point ABI with a standard | |
7405 | double-precision FPU. | |
7406 | @item | |
7407 | 2 for files using the hardware floating-point ABI with a single-precision FPU. | |
7408 | @item | |
7409 | 3 for files using the software floating-point ABI. | |
7410 | @item | |
7411 | 4 for files using the deprecated hardware floating-point ABI which used 64-bit | |
7412 | floating-point registers, 32-bit general-purpose registers and increased the | |
7413 | number of callee-saved floating-point registers. | |
7414 | @item | |
7415 | 5 for files using the hardware floating-point ABI with a double-precision FPU | |
7416 | with either 32-bit or 64-bit floating-point registers and 32-bit | |
7417 | general-purpose registers. | |
7418 | @item | |
7419 | 6 for files using the hardware floating-point ABI with 64-bit floating-point | |
7420 | registers and 32-bit general-purpose registers. | |
7421 | @item | |
7422 | 7 for files using the hardware floating-point ABI with 64-bit floating-point | |
7423 | registers, 32-bit general-purpose registers and a rule that forbids the | |
7424 | direct use of odd-numbered single-precision floating-point registers. | |
7425 | @end itemize | |
7426 | @end table | |
7427 | ||
7428 | @subsection PowerPC Attributes | |
7429 | ||
7430 | @table @r | |
7431 | @item Tag_GNU_Power_ABI_FP (4) | |
7432 | The floating-point ABI used by this object file. The value will be: | |
7433 | ||
7434 | @itemize @bullet | |
7435 | @item | |
7436 | 0 for files not affected by the floating-point ABI. | |
7437 | @item | |
7438 | 1 for files using double-precision hardware floating-point ABI. | |
7439 | @item | |
7440 | 2 for files using the software floating-point ABI. | |
7441 | @item | |
7442 | 3 for files using single-precision hardware floating-point ABI. | |
7443 | @end itemize | |
7444 | ||
7445 | @item Tag_GNU_Power_ABI_Vector (8) | |
7446 | The vector ABI used by this object file. The value will be: | |
7447 | ||
7448 | @itemize @bullet | |
7449 | @item | |
7450 | 0 for files not affected by the vector ABI. | |
7451 | @item | |
7452 | 1 for files using general purpose registers to pass vectors. | |
7453 | @item | |
7454 | 2 for files using AltiVec registers to pass vectors. | |
7455 | @item | |
7456 | 3 for files using SPE registers to pass vectors. | |
7457 | @end itemize | |
7458 | @end table | |
7459 | ||
7460 | @subsection IBM z Systems Attributes | |
7461 | ||
7462 | @table @r | |
7463 | @item Tag_GNU_S390_ABI_Vector (8) | |
7464 | The vector ABI used by this object file. The value will be: | |
7465 | ||
7466 | @itemize @bullet | |
7467 | @item | |
7468 | 0 for files not affected by the vector ABI. | |
7469 | @item | |
7470 | 1 for files using software vector ABI. | |
7471 | @item | |
7472 | 2 for files using hardware vector ABI. | |
7473 | @end itemize | |
7474 | @end table | |
7475 | ||
7476 | @node Defining New Object Attributes | |
7477 | @section Defining New Object Attributes | |
7478 | ||
7479 | If you want to define a new @sc{gnu} object attribute, here are the places you | |
7480 | will need to modify. New attributes should be discussed on the @samp{binutils} | |
7481 | mailing list. | |
7482 | ||
7483 | @itemize @bullet | |
7484 | @item | |
7485 | This manual, which is the official register of attributes. | |
7486 | @item | |
7487 | The header for your architecture @file{include/elf}, to define the tag. | |
7488 | @item | |
7489 | The @file{bfd} support file for your architecture, to merge the attribute | |
7490 | and issue any appropriate link warnings. | |
7491 | @item | |
7492 | Test cases in @file{ld/testsuite} for merging and link warnings. | |
7493 | @item | |
7494 | @file{binutils/readelf.c} to display your attribute. | |
7495 | @item | |
7496 | GCC, if you want the compiler to mark the attribute automatically. | |
7497 | @end itemize | |
7498 | ||
7499 | @end ifset | |
7500 | ||
7501 | @ifset GENERIC | |
7502 | @node Machine Dependencies | |
7503 | @chapter Machine Dependent Features | |
7504 | ||
7505 | @cindex machine dependencies | |
7506 | The machine instruction sets are (almost by definition) different on | |
7507 | each machine where @command{@value{AS}} runs. Floating point representations | |
7508 | vary as well, and @command{@value{AS}} often supports a few additional | |
7509 | directives or command-line options for compatibility with other | |
7510 | assemblers on a particular platform. Finally, some versions of | |
7511 | @command{@value{AS}} support special pseudo-instructions for branch | |
7512 | optimization. | |
7513 | ||
7514 | This chapter discusses most of these differences, though it does not | |
7515 | include details on any machine's instruction set. For details on that | |
7516 | subject, see the hardware manufacturer's manual. | |
7517 | ||
7518 | @menu | |
7519 | @ifset AARCH64 | |
7520 | * AArch64-Dependent:: AArch64 Dependent Features | |
7521 | @end ifset | |
7522 | @ifset ALPHA | |
7523 | * Alpha-Dependent:: Alpha Dependent Features | |
7524 | @end ifset | |
7525 | @ifset ARC | |
7526 | * ARC-Dependent:: ARC Dependent Features | |
7527 | @end ifset | |
7528 | @ifset ARM | |
7529 | * ARM-Dependent:: ARM Dependent Features | |
7530 | @end ifset | |
7531 | @ifset AVR | |
7532 | * AVR-Dependent:: AVR Dependent Features | |
7533 | @end ifset | |
7534 | @ifset Blackfin | |
7535 | * Blackfin-Dependent:: Blackfin Dependent Features | |
7536 | @end ifset | |
7537 | @ifset CR16 | |
7538 | * CR16-Dependent:: CR16 Dependent Features | |
7539 | @end ifset | |
7540 | @ifset CRIS | |
7541 | * CRIS-Dependent:: CRIS Dependent Features | |
7542 | @end ifset | |
7543 | @ifset D10V | |
7544 | * D10V-Dependent:: D10V Dependent Features | |
7545 | @end ifset | |
7546 | @ifset D30V | |
7547 | * D30V-Dependent:: D30V Dependent Features | |
7548 | @end ifset | |
7549 | @ifset EPIPHANY | |
7550 | * Epiphany-Dependent:: EPIPHANY Dependent Features | |
7551 | @end ifset | |
7552 | @ifset H8/300 | |
7553 | * H8/300-Dependent:: Renesas H8/300 Dependent Features | |
7554 | @end ifset | |
7555 | @ifset HPPA | |
7556 | * HPPA-Dependent:: HPPA Dependent Features | |
7557 | @end ifset | |
7558 | @ifset I80386 | |
7559 | * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features | |
7560 | @end ifset | |
7561 | @ifset IA64 | |
7562 | * IA-64-Dependent:: Intel IA-64 Dependent Features | |
7563 | @end ifset | |
7564 | @ifset IP2K | |
7565 | * IP2K-Dependent:: IP2K Dependent Features | |
7566 | @end ifset | |
7567 | @ifset LM32 | |
7568 | * LM32-Dependent:: LM32 Dependent Features | |
7569 | @end ifset | |
7570 | @ifset M32C | |
7571 | * M32C-Dependent:: M32C Dependent Features | |
7572 | @end ifset | |
7573 | @ifset M32R | |
7574 | * M32R-Dependent:: M32R Dependent Features | |
7575 | @end ifset | |
7576 | @ifset M680X0 | |
7577 | * M68K-Dependent:: M680x0 Dependent Features | |
7578 | @end ifset | |
7579 | @ifset M68HC11 | |
7580 | * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features | |
7581 | @end ifset | |
7582 | @ifset S12Z | |
7583 | * S12Z-Dependent:: S12Z Dependent Features | |
7584 | @end ifset | |
7585 | @ifset METAG | |
7586 | * Meta-Dependent :: Meta Dependent Features | |
7587 | @end ifset | |
7588 | @ifset MICROBLAZE | |
7589 | * MicroBlaze-Dependent:: MICROBLAZE Dependent Features | |
7590 | @end ifset | |
7591 | @ifset MIPS | |
7592 | * MIPS-Dependent:: MIPS Dependent Features | |
7593 | @end ifset | |
7594 | @ifset MMIX | |
7595 | * MMIX-Dependent:: MMIX Dependent Features | |
7596 | @end ifset | |
7597 | @ifset MSP430 | |
7598 | * MSP430-Dependent:: MSP430 Dependent Features | |
7599 | @end ifset | |
7600 | @ifset NDS32 | |
7601 | * NDS32-Dependent:: Andes NDS32 Dependent Features | |
7602 | @end ifset | |
7603 | @ifset NIOSII | |
7604 | * NiosII-Dependent:: Altera Nios II Dependent Features | |
7605 | @end ifset | |
7606 | @ifset NS32K | |
7607 | * NS32K-Dependent:: NS32K Dependent Features | |
7608 | @end ifset | |
7609 | @ifset PDP11 | |
7610 | * PDP-11-Dependent:: PDP-11 Dependent Features | |
7611 | @end ifset | |
7612 | @ifset PJ | |
7613 | * PJ-Dependent:: picoJava Dependent Features | |
7614 | @end ifset | |
7615 | @ifset PPC | |
7616 | * PPC-Dependent:: PowerPC Dependent Features | |
7617 | @end ifset | |
7618 | @ifset PRU | |
7619 | * PRU-Dependent:: PRU Dependent Features | |
7620 | @end ifset | |
7621 | @ifset RISCV | |
7622 | * RISC-V-Dependent:: RISC-V Dependent Features | |
7623 | @end ifset | |
7624 | @ifset RL78 | |
7625 | * RL78-Dependent:: RL78 Dependent Features | |
7626 | @end ifset | |
7627 | @ifset RX | |
7628 | * RX-Dependent:: RX Dependent Features | |
7629 | @end ifset | |
7630 | @ifset S390 | |
7631 | * S/390-Dependent:: IBM S/390 Dependent Features | |
7632 | @end ifset | |
7633 | @ifset SCORE | |
7634 | * SCORE-Dependent:: SCORE Dependent Features | |
7635 | @end ifset | |
7636 | @ifset SH | |
7637 | * SH-Dependent:: Renesas / SuperH SH Dependent Features | |
7638 | @end ifset | |
7639 | @ifset SPARC | |
7640 | * Sparc-Dependent:: SPARC Dependent Features | |
7641 | @end ifset | |
7642 | @ifset TIC54X | |
7643 | * TIC54X-Dependent:: TI TMS320C54x Dependent Features | |
7644 | @end ifset | |
7645 | @ifset TIC6X | |
7646 | * TIC6X-Dependent :: TI TMS320C6x Dependent Features | |
7647 | @end ifset | |
7648 | @ifset TILEGX | |
7649 | * TILE-Gx-Dependent :: Tilera TILE-Gx Dependent Features | |
7650 | @end ifset | |
7651 | @ifset TILEPRO | |
7652 | * TILEPro-Dependent :: Tilera TILEPro Dependent Features | |
7653 | @end ifset | |
7654 | @ifset V850 | |
7655 | * V850-Dependent:: V850 Dependent Features | |
7656 | @end ifset | |
7657 | @ifset VAX | |
7658 | * Vax-Dependent:: VAX Dependent Features | |
7659 | @end ifset | |
7660 | @ifset VISIUM | |
7661 | * Visium-Dependent:: Visium Dependent Features | |
7662 | @end ifset | |
7663 | @ifset WASM32 | |
7664 | * WebAssembly-Dependent:: WebAssembly Dependent Features | |
7665 | @end ifset | |
7666 | @ifset XGATE | |
7667 | * XGATE-Dependent:: XGATE Dependent Features | |
7668 | @end ifset | |
7669 | @ifset XSTORMY16 | |
7670 | * XSTORMY16-Dependent:: XStormy16 Dependent Features | |
7671 | @end ifset | |
7672 | @ifset XTENSA | |
7673 | * Xtensa-Dependent:: Xtensa Dependent Features | |
7674 | @end ifset | |
7675 | @ifset Z80 | |
7676 | * Z80-Dependent:: Z80 Dependent Features | |
7677 | @end ifset | |
7678 | @ifset Z8000 | |
7679 | * Z8000-Dependent:: Z8000 Dependent Features | |
7680 | @end ifset | |
7681 | @end menu | |
7682 | ||
7683 | @lowersections | |
7684 | @end ifset | |
7685 | ||
7686 | @c The following major nodes are *sections* in the GENERIC version, *chapters* | |
7687 | @c in single-cpu versions. This is mainly achieved by @lowersections. There is a | |
7688 | @c peculiarity: to preserve cross-references, there must be a node called | |
7689 | @c "Machine Dependencies". Hence the conditional nodenames in each | |
7690 | @c major node below. Node defaulting in makeinfo requires adjacency of | |
7691 | @c node and sectioning commands; hence the repetition of @chapter BLAH | |
7692 | @c in both conditional blocks. | |
7693 | ||
7694 | @ifset AARCH64 | |
7695 | @include c-aarch64.texi | |
7696 | @end ifset | |
7697 | ||
7698 | @ifset ALPHA | |
7699 | @include c-alpha.texi | |
7700 | @end ifset | |
7701 | ||
7702 | @ifset ARC | |
7703 | @include c-arc.texi | |
7704 | @end ifset | |
7705 | ||
7706 | @ifset ARM | |
7707 | @include c-arm.texi | |
7708 | @end ifset | |
7709 | ||
7710 | @ifset AVR | |
7711 | @include c-avr.texi | |
7712 | @end ifset | |
7713 | ||
7714 | @ifset Blackfin | |
7715 | @include c-bfin.texi | |
7716 | @end ifset | |
7717 | ||
7718 | @ifset CR16 | |
7719 | @include c-cr16.texi | |
7720 | @end ifset | |
7721 | ||
7722 | @ifset CRIS | |
7723 | @include c-cris.texi | |
7724 | @end ifset | |
7725 | ||
7726 | @ifset Renesas-all | |
7727 | @ifclear GENERIC | |
7728 | @node Machine Dependencies | |
7729 | @chapter Machine Dependent Features | |
7730 | ||
7731 | The machine instruction sets are different on each Renesas chip family, | |
7732 | and there are also some syntax differences among the families. This | |
7733 | chapter describes the specific @command{@value{AS}} features for each | |
7734 | family. | |
7735 | ||
7736 | @menu | |
7737 | * H8/300-Dependent:: Renesas H8/300 Dependent Features | |
7738 | * SH-Dependent:: Renesas SH Dependent Features | |
7739 | @end menu | |
7740 | @lowersections | |
7741 | @end ifclear | |
7742 | @end ifset | |
7743 | ||
7744 | @ifset D10V | |
7745 | @include c-d10v.texi | |
7746 | @end ifset | |
7747 | ||
7748 | @ifset D30V | |
7749 | @include c-d30v.texi | |
7750 | @end ifset | |
7751 | ||
7752 | @ifset EPIPHANY | |
7753 | @include c-epiphany.texi | |
7754 | @end ifset | |
7755 | ||
7756 | @ifset H8/300 | |
7757 | @include c-h8300.texi | |
7758 | @end ifset | |
7759 | ||
7760 | @ifset HPPA | |
7761 | @include c-hppa.texi | |
7762 | @end ifset | |
7763 | ||
7764 | @ifset I80386 | |
7765 | @include c-i386.texi | |
7766 | @end ifset | |
7767 | ||
7768 | @ifset IA64 | |
7769 | @include c-ia64.texi | |
7770 | @end ifset | |
7771 | ||
7772 | @ifset IP2K | |
7773 | @include c-ip2k.texi | |
7774 | @end ifset | |
7775 | ||
7776 | @ifset LM32 | |
7777 | @include c-lm32.texi | |
7778 | @end ifset | |
7779 | ||
7780 | @ifset M32C | |
7781 | @include c-m32c.texi | |
7782 | @end ifset | |
7783 | ||
7784 | @ifset M32R | |
7785 | @include c-m32r.texi | |
7786 | @end ifset | |
7787 | ||
7788 | @ifset M680X0 | |
7789 | @include c-m68k.texi | |
7790 | @end ifset | |
7791 | ||
7792 | @ifset M68HC11 | |
7793 | @include c-m68hc11.texi | |
7794 | @end ifset | |
7795 | ||
7796 | @ifset S12Z | |
7797 | @include c-s12z.texi | |
7798 | @end ifset | |
7799 | ||
7800 | @ifset METAG | |
7801 | @include c-metag.texi | |
7802 | @end ifset | |
7803 | ||
7804 | @ifset MICROBLAZE | |
7805 | @include c-microblaze.texi | |
7806 | @end ifset | |
7807 | ||
7808 | @ifset MIPS | |
7809 | @include c-mips.texi | |
7810 | @end ifset | |
7811 | ||
7812 | @ifset MMIX | |
7813 | @include c-mmix.texi | |
7814 | @end ifset | |
7815 | ||
7816 | @ifset MSP430 | |
7817 | @include c-msp430.texi | |
7818 | @end ifset | |
7819 | ||
7820 | @ifset NDS32 | |
7821 | @include c-nds32.texi | |
7822 | @end ifset | |
7823 | ||
7824 | @ifset NIOSII | |
7825 | @include c-nios2.texi | |
7826 | @end ifset | |
7827 | ||
7828 | @ifset NS32K | |
7829 | @include c-ns32k.texi | |
7830 | @end ifset | |
7831 | ||
7832 | @ifset PDP11 | |
7833 | @include c-pdp11.texi | |
7834 | @end ifset | |
7835 | ||
7836 | @ifset PJ | |
7837 | @include c-pj.texi | |
7838 | @end ifset | |
7839 | ||
7840 | @ifset PPC | |
7841 | @include c-ppc.texi | |
7842 | @end ifset | |
7843 | ||
7844 | @ifset PRU | |
7845 | @include c-pru.texi | |
7846 | @end ifset | |
7847 | ||
7848 | @ifset RISCV | |
7849 | @include c-riscv.texi | |
7850 | @end ifset | |
7851 | ||
7852 | @ifset RL78 | |
7853 | @include c-rl78.texi | |
7854 | @end ifset | |
7855 | ||
7856 | @ifset RX | |
7857 | @include c-rx.texi | |
7858 | @end ifset | |
7859 | ||
7860 | @ifset S390 | |
7861 | @include c-s390.texi | |
7862 | @end ifset | |
7863 | ||
7864 | @ifset SCORE | |
7865 | @include c-score.texi | |
7866 | @end ifset | |
7867 | ||
7868 | @ifset SH | |
7869 | @include c-sh.texi | |
7870 | @end ifset | |
7871 | ||
7872 | @ifset SPARC | |
7873 | @include c-sparc.texi | |
7874 | @end ifset | |
7875 | ||
7876 | @ifset TIC54X | |
7877 | @include c-tic54x.texi | |
7878 | @end ifset | |
7879 | ||
7880 | @ifset TIC6X | |
7881 | @include c-tic6x.texi | |
7882 | @end ifset | |
7883 | ||
7884 | @ifset TILEGX | |
7885 | @include c-tilegx.texi | |
7886 | @end ifset | |
7887 | ||
7888 | @ifset TILEPRO | |
7889 | @include c-tilepro.texi | |
7890 | @end ifset | |
7891 | ||
7892 | @ifset V850 | |
7893 | @include c-v850.texi | |
7894 | @end ifset | |
7895 | ||
7896 | @ifset VAX | |
7897 | @include c-vax.texi | |
7898 | @end ifset | |
7899 | ||
7900 | @ifset VISIUM | |
7901 | @include c-visium.texi | |
7902 | @end ifset | |
7903 | ||
7904 | @ifset WASM32 | |
7905 | @include c-wasm32.texi | |
7906 | @end ifset | |
7907 | ||
7908 | @ifset XGATE | |
7909 | @include c-xgate.texi | |
7910 | @end ifset | |
7911 | ||
7912 | @ifset XSTORMY16 | |
7913 | @include c-xstormy16.texi | |
7914 | @end ifset | |
7915 | ||
7916 | @ifset XTENSA | |
7917 | @include c-xtensa.texi | |
7918 | @end ifset | |
7919 | ||
7920 | @ifset Z80 | |
7921 | @include c-z80.texi | |
7922 | @end ifset | |
7923 | ||
7924 | @ifset Z8000 | |
7925 | @include c-z8k.texi | |
7926 | @end ifset | |
7927 | ||
7928 | @ifset GENERIC | |
7929 | @c reverse effect of @down at top of generic Machine-Dep chapter | |
7930 | @raisesections | |
7931 | @end ifset | |
7932 | ||
7933 | @node Reporting Bugs | |
7934 | @chapter Reporting Bugs | |
7935 | @cindex bugs in assembler | |
7936 | @cindex reporting bugs in assembler | |
7937 | ||
7938 | Your bug reports play an essential role in making @command{@value{AS}} reliable. | |
7939 | ||
7940 | Reporting a bug may help you by bringing a solution to your problem, or it may | |
7941 | not. But in any case the principal function of a bug report is to help the | |
7942 | entire community by making the next version of @command{@value{AS}} work better. | |
7943 | Bug reports are your contribution to the maintenance of @command{@value{AS}}. | |
7944 | ||
7945 | In order for a bug report to serve its purpose, you must include the | |
7946 | information that enables us to fix the bug. | |
7947 | ||
7948 | @menu | |
7949 | * Bug Criteria:: Have you found a bug? | |
7950 | * Bug Reporting:: How to report bugs | |
7951 | @end menu | |
7952 | ||
7953 | @node Bug Criteria | |
7954 | @section Have You Found a Bug? | |
7955 | @cindex bug criteria | |
7956 | ||
7957 | If you are not sure whether you have found a bug, here are some guidelines: | |
7958 | ||
7959 | @itemize @bullet | |
7960 | @cindex fatal signal | |
7961 | @cindex assembler crash | |
7962 | @cindex crash of assembler | |
7963 | @item | |
7964 | If the assembler gets a fatal signal, for any input whatever, that is a | |
7965 | @command{@value{AS}} bug. Reliable assemblers never crash. | |
7966 | ||
7967 | @cindex error on valid input | |
7968 | @item | |
7969 | If @command{@value{AS}} produces an error message for valid input, that is a bug. | |
7970 | ||
7971 | @cindex invalid input | |
7972 | @item | |
7973 | If @command{@value{AS}} does not produce an error message for invalid input, that | |
7974 | is a bug. However, you should note that your idea of ``invalid input'' might | |
7975 | be our idea of ``an extension'' or ``support for traditional practice''. | |
7976 | ||
7977 | @item | |
7978 | If you are an experienced user of assemblers, your suggestions for improvement | |
7979 | of @command{@value{AS}} are welcome in any case. | |
7980 | @end itemize | |
7981 | ||
7982 | @node Bug Reporting | |
7983 | @section How to Report Bugs | |
7984 | @cindex bug reports | |
7985 | @cindex assembler bugs, reporting | |
7986 | ||
7987 | A number of companies and individuals offer support for @sc{gnu} products. If | |
7988 | you obtained @command{@value{AS}} from a support organization, we recommend you | |
7989 | contact that organization first. | |
7990 | ||
7991 | You can find contact information for many support companies and | |
7992 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs | |
7993 | distribution. | |
7994 | ||
7995 | @ifset BUGURL | |
7996 | In any event, we also recommend that you send bug reports for @command{@value{AS}} | |
7997 | to @value{BUGURL}. | |
7998 | @end ifset | |
7999 | ||
8000 | The fundamental principle of reporting bugs usefully is this: | |
8001 | @strong{report all the facts}. If you are not sure whether to state a | |
8002 | fact or leave it out, state it! | |
8003 | ||
8004 | Often people omit facts because they think they know what causes the problem | |
8005 | and assume that some details do not matter. Thus, you might assume that the | |
8006 | name of a symbol you use in an example does not matter. Well, probably it does | |
8007 | not, but one cannot be sure. Perhaps the bug is a stray memory reference which | |
8008 | happens to fetch from the location where that name is stored in memory; | |
8009 | perhaps, if the name were different, the contents of that location would fool | |
8010 | the assembler into doing the right thing despite the bug. Play it safe and | |
8011 | give a specific, complete example. That is the easiest thing for you to do, | |
8012 | and the most helpful. | |
8013 | ||
8014 | Keep in mind that the purpose of a bug report is to enable us to fix the bug if | |
8015 | it is new to us. Therefore, always write your bug reports on the assumption | |
8016 | that the bug has not been reported previously. | |
8017 | ||
8018 | Sometimes people give a few sketchy facts and ask, ``Does this ring a | |
8019 | bell?'' This cannot help us fix a bug, so it is basically useless. We | |
8020 | respond by asking for enough details to enable us to investigate. | |
8021 | You might as well expedite matters by sending them to begin with. | |
8022 | ||
8023 | To enable us to fix the bug, you should include all these things: | |
8024 | ||
8025 | @itemize @bullet | |
8026 | @item | |
8027 | The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start | |
8028 | it with the @samp{--version} argument. | |
8029 | ||
8030 | Without this, we will not know whether there is any point in looking for | |
8031 | the bug in the current version of @command{@value{AS}}. | |
8032 | ||
8033 | @item | |
8034 | Any patches you may have applied to the @command{@value{AS}} source. | |
8035 | ||
8036 | @item | |
8037 | The type of machine you are using, and the operating system name and | |
8038 | version number. | |
8039 | ||
8040 | @item | |
8041 | What compiler (and its version) was used to compile @command{@value{AS}}---e.g. | |
8042 | ``@code{gcc-2.7}''. | |
8043 | ||
8044 | @item | |
8045 | The command arguments you gave the assembler to assemble your example and | |
8046 | observe the bug. To guarantee you will not omit something important, list them | |
8047 | all. A copy of the Makefile (or the output from make) is sufficient. | |
8048 | ||
8049 | If we were to try to guess the arguments, we would probably guess wrong | |
8050 | and then we might not encounter the bug. | |
8051 | ||
8052 | @item | |
8053 | A complete input file that will reproduce the bug. If the bug is observed when | |
8054 | the assembler is invoked via a compiler, send the assembler source, not the | |
8055 | high level language source. Most compilers will produce the assembler source | |
8056 | when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use | |
8057 | the options @samp{-v --save-temps}; this will save the assembler source in a | |
8058 | file with an extension of @file{.s}, and also show you exactly how | |
8059 | @command{@value{AS}} is being run. | |
8060 | ||
8061 | @item | |
8062 | A description of what behavior you observe that you believe is | |
8063 | incorrect. For example, ``It gets a fatal signal.'' | |
8064 | ||
8065 | Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we | |
8066 | will certainly notice it. But if the bug is incorrect output, we might not | |
8067 | notice unless it is glaringly wrong. You might as well not give us a chance to | |
8068 | make a mistake. | |
8069 | ||
8070 | Even if the problem you experience is a fatal signal, you should still say so | |
8071 | explicitly. Suppose something strange is going on, such as, your copy of | |
8072 | @command{@value{AS}} is out of sync, or you have encountered a bug in the C | |
8073 | library on your system. (This has happened!) Your copy might crash and ours | |
8074 | would not. If you told us to expect a crash, then when ours fails to crash, we | |
8075 | would know that the bug was not happening for us. If you had not told us to | |
8076 | expect a crash, then we would not be able to draw any conclusion from our | |
8077 | observations. | |
8078 | ||
8079 | @item | |
8080 | If you wish to suggest changes to the @command{@value{AS}} source, send us context | |
8081 | diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p} | |
8082 | option. Always send diffs from the old file to the new file. If you even | |
8083 | discuss something in the @command{@value{AS}} source, refer to it by context, not | |
8084 | by line number. | |
8085 | ||
8086 | The line numbers in our development sources will not match those in your | |
8087 | sources. Your line numbers would convey no useful information to us. | |
8088 | @end itemize | |
8089 | ||
8090 | Here are some things that are not necessary: | |
8091 | ||
8092 | @itemize @bullet | |
8093 | @item | |
8094 | A description of the envelope of the bug. | |
8095 | ||
8096 | Often people who encounter a bug spend a lot of time investigating | |
8097 | which changes to the input file will make the bug go away and which | |
8098 | changes will not affect it. | |
8099 | ||
8100 | This is often time consuming and not very useful, because the way we | |
8101 | will find the bug is by running a single example under the debugger | |
8102 | with breakpoints, not by pure deduction from a series of examples. | |
8103 | We recommend that you save your time for something else. | |
8104 | ||
8105 | Of course, if you can find a simpler example to report @emph{instead} | |
8106 | of the original one, that is a convenience for us. Errors in the | |
8107 | output will be easier to spot, running under the debugger will take | |
8108 | less time, and so on. | |
8109 | ||
8110 | However, simplification is not vital; if you do not want to do this, | |
8111 | report the bug anyway and send us the entire test case you used. | |
8112 | ||
8113 | @item | |
8114 | A patch for the bug. | |
8115 | ||
8116 | A patch for the bug does help us if it is a good one. But do not omit | |
8117 | the necessary information, such as the test case, on the assumption that | |
8118 | a patch is all we need. We might see problems with your patch and decide | |
8119 | to fix the problem another way, or we might not understand it at all. | |
8120 | ||
8121 | Sometimes with a program as complicated as @command{@value{AS}} it is very hard to | |
8122 | construct an example that will make the program follow a certain path through | |
8123 | the code. If you do not send us the example, we will not be able to construct | |
8124 | one, so we will not be able to verify that the bug is fixed. | |
8125 | ||
8126 | And if we cannot understand what bug you are trying to fix, or why your | |
8127 | patch should be an improvement, we will not install it. A test case will | |
8128 | help us to understand. | |
8129 | ||
8130 | @item | |
8131 | A guess about what the bug is or what it depends on. | |
8132 | ||
8133 | Such guesses are usually wrong. Even we cannot guess right about such | |
8134 | things without first using the debugger to find the facts. | |
8135 | @end itemize | |
8136 | ||
8137 | @node Acknowledgements | |
8138 | @chapter Acknowledgements | |
8139 | ||
8140 | If you have contributed to GAS and your name isn't listed here, | |
8141 | it is not meant as a slight. We just don't know about it. Send mail to the | |
8142 | maintainer, and we'll correct the situation. Currently | |
8143 | @c (October 2012), | |
8144 | the maintainer is Nick Clifton (email address @code{nickc@@redhat.com}). | |
8145 | ||
8146 | Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any | |
8147 | more details?} | |
8148 | ||
8149 | Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug | |
8150 | information and the 68k series machines, most of the preprocessing pass, and | |
8151 | extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}. | |
8152 | ||
8153 | K. Richard Pixley maintained GAS for a while, adding various enhancements and | |
8154 | many bug fixes, including merging support for several processors, breaking GAS | |
8155 | up to handle multiple object file format back ends (including heavy rewrite, | |
8156 | testing, an integration of the coff and b.out back ends), adding configuration | |
8157 | including heavy testing and verification of cross assemblers and file splits | |
8158 | and renaming, converted GAS to strictly ANSI C including full prototypes, added | |
8159 | support for m680[34]0 and cpu32, did considerable work on i960 including a COFF | |
8160 | port (including considerable amounts of reverse engineering), a SPARC opcode | |
8161 | file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know'' | |
8162 | assertions and made them work, much other reorganization, cleanup, and lint. | |
8163 | ||
8164 | Ken Raeburn wrote the high-level BFD interface code to replace most of the code | |
8165 | in format-specific I/O modules. | |
8166 | ||
8167 | The original VMS support was contributed by David L. Kashtan. Eric Youngdale | |
8168 | has done much work with it since. | |
8169 | ||
8170 | The Intel 80386 machine description was written by Eliot Dresselhaus. | |
8171 | ||
8172 | Minh Tran-Le at IntelliCorp contributed some AIX 386 support. | |
8173 | ||
8174 | The Motorola 88k machine description was contributed by Devon Bowen of Buffalo | |
8175 | University and Torbjorn Granlund of the Swedish Institute of Computer Science. | |
8176 | ||
8177 | Keith Knowles at the Open Software Foundation wrote the original MIPS back end | |
8178 | (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support | |
8179 | (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to | |
8180 | support a.out format. | |
8181 | ||
8182 | Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k, | |
8183 | tc-h8300), and IEEE 695 object file format (obj-ieee), was written by | |
8184 | Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to | |
8185 | use BFD for some low-level operations, for use with the H8/300 and AMD 29k | |
8186 | targets. | |
8187 | ||
8188 | John Gilmore built the AMD 29000 support, added @code{.include} support, and | |
8189 | simplified the configuration of which versions accept which directives. He | |
8190 | updated the 68k machine description so that Motorola's opcodes always produced | |
8191 | fixed-size instructions (e.g., @code{jsr}), while synthetic instructions | |
8192 | remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested | |
8193 | cross-compilation support, and one bug in relaxation that took a week and | |
8194 | required the proverbial one-bit fix. | |
8195 | ||
8196 | Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the | |
8197 | 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix), | |
8198 | added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and | |
8199 | PowerPC assembler, and made a few other minor patches. | |
8200 | ||
8201 | Steve Chamberlain made GAS able to generate listings. | |
8202 | ||
8203 | Hewlett-Packard contributed support for the HP9000/300. | |
8204 | ||
8205 | Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM) | |
8206 | along with a fairly extensive HPPA testsuite (for both SOM and ELF object | |
8207 | formats). This work was supported by both the Center for Software Science at | |
8208 | the University of Utah and Cygnus Support. | |
8209 | ||
8210 | Support for ELF format files has been worked on by Mark Eichin of Cygnus | |
8211 | Support (original, incomplete implementation for SPARC), Pete Hoogenboom and | |
8212 | Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open | |
8213 | Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc, | |
8214 | and some initial 64-bit support). | |
8215 | ||
8216 | Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture. | |
8217 | ||
8218 | Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD | |
8219 | support for openVMS/Alpha. | |
8220 | ||
8221 | Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic* | |
8222 | flavors. | |
8223 | ||
8224 | David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica, | |
8225 | Inc.@: added support for Xtensa processors. | |
8226 | ||
8227 | Several engineers at Cygnus Support have also provided many small bug fixes and | |
8228 | configuration enhancements. | |
8229 | ||
8230 | Jon Beniston added support for the Lattice Mico32 architecture. | |
8231 | ||
8232 | Many others have contributed large or small bugfixes and enhancements. If | |
8233 | you have contributed significant work and are not mentioned on this list, and | |
8234 | want to be, let us know. Some of the history has been lost; we are not | |
8235 | intentionally leaving anyone out. | |
8236 | ||
8237 | @node GNU Free Documentation License | |
8238 | @appendix GNU Free Documentation License | |
8239 | @include fdl.texi | |
8240 | ||
8241 | @node AS Index | |
8242 | @unnumbered AS Index | |
8243 | ||
8244 | @printindex cp | |
8245 | ||
8246 | @bye | |
8247 | @c Local Variables: | |
8248 | @c fill-column: 79 | |
8249 | @c End: |