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252b5132 | 1 | \input texinfo @c -*-Texinfo-*- |
f7e42eb4 | 2 | @c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, |
ad22bfe8 | 3 | @c 2001, 2002, 2003, 2004, 2005, 2006, 2007 |
252b5132 RH |
4 | @c Free Software Foundation, Inc. |
5 | @c UPDATE!! On future updates-- | |
6 | @c (1) check for new machine-dep cmdline options in | |
7 | @c md_parse_option definitions in config/tc-*.c | |
8 | @c (2) for platform-specific directives, examine md_pseudo_op | |
9 | @c in config/tc-*.c | |
10 | @c (3) for object-format specific directives, examine obj_pseudo_op | |
11 | @c in config/obj-*.c | |
12 | @c (4) portable directives in potable[] in read.c | |
13 | @c %**start of header | |
14 | @setfilename as.info | |
15 | @c ---config--- | |
a4fb0134 SC |
16 | @macro gcctabopt{body} |
17 | @code{\body\} | |
18 | @end macro | |
252b5132 RH |
19 | @c defaults, config file may override: |
20 | @set have-stabs | |
21 | @c --- | |
4a4c4a1d MR |
22 | @c man begin NAME |
23 | @c --- | |
252b5132 | 24 | @include asconfig.texi |
c428fa83 | 25 | @include bfdver.texi |
252b5132 | 26 | @c --- |
0285c67d | 27 | @c man end |
4a4c4a1d | 28 | @c --- |
252b5132 | 29 | @c common OR combinations of conditions |
c1253627 NC |
30 | @ifset COFF |
31 | @set COFF-ELF | |
32 | @end ifset | |
33 | @ifset ELF | |
34 | @set COFF-ELF | |
35 | @end ifset | |
252b5132 RH |
36 | @ifset AOUT |
37 | @set aout-bout | |
38 | @end ifset | |
39 | @ifset ARM/Thumb | |
40 | @set ARM | |
41 | @end ifset | |
42 | @ifset BOUT | |
43 | @set aout-bout | |
44 | @end ifset | |
45 | @ifset H8/300 | |
46 | @set H8 | |
47 | @end ifset | |
252b5132 RH |
48 | @ifset SH |
49 | @set H8 | |
50 | @end ifset | |
51 | @ifset HPPA | |
52 | @set abnormal-separator | |
53 | @end ifset | |
54 | @c ------------ | |
55 | @ifset GENERIC | |
56 | @settitle Using @value{AS} | |
57 | @end ifset | |
58 | @ifclear GENERIC | |
59 | @settitle Using @value{AS} (@value{TARGET}) | |
60 | @end ifclear | |
61 | @setchapternewpage odd | |
62 | @c %**end of header | |
63 | ||
64 | @c @smallbook | |
65 | @c @set SMALL | |
66 | @c WARE! Some of the machine-dependent sections contain tables of machine | |
67 | @c instructions. Except in multi-column format, these tables look silly. | |
68 | @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so | |
69 | @c the multi-col format is faked within @example sections. | |
70 | @c | |
71 | @c Again unfortunately, the natural size that fits on a page, for these tables, | |
72 | @c is different depending on whether or not smallbook is turned on. | |
73 | @c This matters, because of order: text flow switches columns at each page | |
74 | @c break. | |
75 | @c | |
76 | @c The format faked in this source works reasonably well for smallbook, | |
77 | @c not well for the default large-page format. This manual expects that if you | |
78 | @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the | |
79 | @c tables in question. You can turn on one without the other at your | |
80 | @c discretion, of course. | |
81 | @ifinfo | |
82 | @set SMALL | |
83 | @c the insn tables look just as silly in info files regardless of smallbook, | |
84 | @c might as well show 'em anyways. | |
85 | @end ifinfo | |
86 | ||
87 | @ifinfo | |
88 | @format | |
89 | START-INFO-DIR-ENTRY | |
90 | * As: (as). The GNU assembler. | |
59455fb1 | 91 | * Gas: (as). The GNU assembler. |
252b5132 RH |
92 | END-INFO-DIR-ENTRY |
93 | @end format | |
94 | @end ifinfo | |
95 | ||
96 | @finalout | |
97 | @syncodeindex ky cp | |
98 | ||
0e9517a9 | 99 | @copying |
252b5132 RH |
100 | This file documents the GNU Assembler "@value{AS}". |
101 | ||
0285c67d | 102 | @c man begin COPYRIGHT |
0e9517a9 | 103 | Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002, |
ad22bfe8 | 104 | 2006, 2007 Free Software Foundation, Inc. |
252b5132 | 105 | |
0285c67d NC |
106 | Permission is granted to copy, distribute and/or modify this document |
107 | under the terms of the GNU Free Documentation License, Version 1.1 | |
108 | or any later version published by the Free Software Foundation; | |
109 | with no Invariant Sections, with no Front-Cover Texts, and with no | |
110 | Back-Cover Texts. A copy of the license is included in the | |
c1253627 | 111 | section entitled ``GNU Free Documentation License''. |
0285c67d NC |
112 | |
113 | @c man end | |
0e9517a9 | 114 | @end copying |
252b5132 RH |
115 | |
116 | @titlepage | |
117 | @title Using @value{AS} | |
118 | @subtitle The @sc{gnu} Assembler | |
119 | @ifclear GENERIC | |
120 | @subtitle for the @value{TARGET} family | |
121 | @end ifclear | |
e49e529d JM |
122 | @ifset VERSION_PACKAGE |
123 | @sp 1 | |
124 | @subtitle @value{VERSION_PACKAGE} | |
125 | @end ifset | |
252b5132 RH |
126 | @sp 1 |
127 | @subtitle Version @value{VERSION} | |
128 | @sp 1 | |
129 | @sp 13 | |
b45619c0 | 130 | The Free Software Foundation Inc.@: thanks The Nice Computer |
252b5132 | 131 | Company of Australia for loaning Dean Elsner to write the |
a4fb0134 | 132 | first (Vax) version of @command{as} for Project @sc{gnu}. |
252b5132 RH |
133 | The proprietors, management and staff of TNCCA thank FSF for |
134 | distracting the boss while they got some work | |
135 | done. | |
136 | @sp 3 | |
137 | @author Dean Elsner, Jay Fenlason & friends | |
138 | @page | |
139 | @tex | |
140 | {\parskip=0pt | |
141 | \hfill {\it Using {\tt @value{AS}}}\par | |
142 | \hfill Edited by Cygnus Support\par | |
143 | } | |
144 | %"boxit" macro for figures: | |
145 | %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3) | |
146 | \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt | |
147 | \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil | |
148 | #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline | |
149 | \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box | |
150 | @end tex | |
151 | ||
152 | @vskip 0pt plus 1filll | |
ad22bfe8 JM |
153 | Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002, |
154 | 2006, 2007 Free Software Foundation, Inc. | |
252b5132 | 155 | |
cf055d54 NC |
156 | Permission is granted to copy, distribute and/or modify this document |
157 | under the terms of the GNU Free Documentation License, Version 1.1 | |
158 | or any later version published by the Free Software Foundation; | |
159 | with no Invariant Sections, with no Front-Cover Texts, and with no | |
160 | Back-Cover Texts. A copy of the license is included in the | |
c1253627 | 161 | section entitled ``GNU Free Documentation License''. |
252b5132 | 162 | |
252b5132 | 163 | @end titlepage |
4ecceb71 | 164 | @contents |
252b5132 | 165 | |
2e64b665 | 166 | @ifnottex |
252b5132 RH |
167 | @node Top |
168 | @top Using @value{AS} | |
169 | ||
e49e529d JM |
170 | This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} |
171 | @ifset VERSION_PACKAGE | |
172 | @value{VERSION_PACKAGE} | |
173 | @end ifset | |
174 | version @value{VERSION}. | |
252b5132 | 175 | @ifclear GENERIC |
a4fb0134 | 176 | This version of the file describes @command{@value{AS}} configured to generate |
252b5132 RH |
177 | code for @value{TARGET} architectures. |
178 | @end ifclear | |
cf055d54 NC |
179 | |
180 | This document is distributed under the terms of the GNU Free | |
181 | Documentation License. A copy of the license is included in the | |
c1253627 | 182 | section entitled ``GNU Free Documentation License''. |
cf055d54 | 183 | |
252b5132 RH |
184 | @menu |
185 | * Overview:: Overview | |
186 | * Invoking:: Command-Line Options | |
187 | * Syntax:: Syntax | |
188 | * Sections:: Sections and Relocation | |
189 | * Symbols:: Symbols | |
190 | * Expressions:: Expressions | |
191 | * Pseudo Ops:: Assembler Directives | |
3a99f02f DJ |
192 | @ifset ELF |
193 | * Object Attributes:: Object Attributes | |
194 | @end ifset | |
252b5132 RH |
195 | * Machine Dependencies:: Machine Dependent Features |
196 | * Reporting Bugs:: Reporting Bugs | |
197 | * Acknowledgements:: Who Did What | |
cf055d54 | 198 | * GNU Free Documentation License:: GNU Free Documentation License |
28c9d252 | 199 | * AS Index:: AS Index |
252b5132 | 200 | @end menu |
2e64b665 | 201 | @end ifnottex |
252b5132 RH |
202 | |
203 | @node Overview | |
204 | @chapter Overview | |
205 | @iftex | |
a4fb0134 | 206 | This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}. |
252b5132 | 207 | @ifclear GENERIC |
a4fb0134 | 208 | This version of the manual describes @command{@value{AS}} configured to generate |
252b5132 RH |
209 | code for @value{TARGET} architectures. |
210 | @end ifclear | |
211 | @end iftex | |
212 | ||
213 | @cindex invocation summary | |
214 | @cindex option summary | |
215 | @cindex summary of options | |
a4fb0134 | 216 | Here is a brief summary of how to invoke @command{@value{AS}}. For details, |
96e9638b | 217 | see @ref{Invoking,,Command-Line Options}. |
252b5132 | 218 | |
0285c67d NC |
219 | @c man title AS the portable GNU assembler. |
220 | ||
a4fb0134 | 221 | @ignore |
0285c67d NC |
222 | @c man begin SEEALSO |
223 | gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}. | |
224 | @c man end | |
a4fb0134 | 225 | @end ignore |
0285c67d | 226 | |
252b5132 RH |
227 | @c We don't use deffn and friends for the following because they seem |
228 | @c to be limited to one line for the header. | |
229 | @smallexample | |
0285c67d | 230 | @c man begin SYNOPSIS |
83f10cb2 | 231 | @value{AS} [@b{-a}[@b{cdghlns}][=@var{file}]] [@b{--alternate}] [@b{-D}] |
3d6b762c | 232 | [@b{--debug-prefix-map} @var{old}=@var{new}] |
4bdd3565 NC |
233 | [@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}] |
234 | [@b{--gstabs+}] [@b{--gdwarf-2}] [@b{--help}] [@b{-I} @var{dir}] [@b{-J}] | |
235 | [@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}] | |
236 | [@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}] | |
237 | [@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}] [@b{-o} | |
238 | @var{objfile}] [@b{-R}] [@b{--reduce-memory-overheads}] [@b{--statistics}] | |
239 | [@b{-v}] [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] | |
a0b7da79 MM |
240 | [@b{--fatal-warnings}] [@b{-w}] [@b{-x}] [@b{-Z}] [@b{@@@var{FILE}}] |
241 | [@b{--target-help}] [@var{target-options}] | |
242 | [@b{--}|@var{files} @dots{}] | |
a4fb0134 SC |
243 | @c |
244 | @c Target dependent options are listed below. Keep the list sorted. | |
245 | @c Add an empty line for separation. | |
625e1353 RH |
246 | @ifset ALPHA |
247 | ||
248 | @emph{Target Alpha options:} | |
249 | [@b{-m@var{cpu}}] | |
250 | [@b{-mdebug} | @b{-no-mdebug}] | |
251 | [@b{-relax}] [@b{-g}] [@b{-G@var{size}}] | |
252 | [@b{-F}] [@b{-32addr}] | |
253 | @end ifset | |
252b5132 | 254 | @ifset ARC |
a4fb0134 SC |
255 | |
256 | @emph{Target ARC options:} | |
257 | [@b{-marc[5|6|7|8]}] | |
258 | [@b{-EB}|@b{-EL}] | |
252b5132 RH |
259 | @end ifset |
260 | @ifset ARM | |
a4fb0134 SC |
261 | |
262 | @emph{Target ARM options:} | |
03b1477f | 263 | @c Don't document the deprecated options |
92081f48 HPN |
264 | [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]] |
265 | [@b{-march}=@var{architecture}[+@var{extension}@dots{}]] | |
33a392fb PB |
266 | [@b{-mfpu}=@var{floating-point-format}] |
267 | [@b{-mfloat-abi}=@var{abi}] | |
d507cf36 | 268 | [@b{-meabi}=@var{ver}] |
03b1477f | 269 | [@b{-mthumb}] |
a4fb0134 SC |
270 | [@b{-EB}|@b{-EL}] |
271 | [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}| | |
272 | @b{-mapcs-reentrant}] | |
7f266840 | 273 | [@b{-mthumb-interwork}] [@b{-k}] |
252b5132 | 274 | @end ifset |
328eb32e HPN |
275 | @ifset CRIS |
276 | ||
277 | @emph{Target CRIS options:} | |
278 | [@b{--underscore} | @b{--no-underscore}] | |
279 | [@b{--pic}] [@b{-N}] | |
280 | [@b{--emulation=criself} | @b{--emulation=crisaout}] | |
ae57792d | 281 | [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}] |
328eb32e HPN |
282 | @c Deprecated -- deliberately not documented. |
283 | @c [@b{-h}] [@b{-H}] | |
284 | @end ifset | |
252b5132 | 285 | @ifset D10V |
a4fb0134 SC |
286 | |
287 | @emph{Target D10V options:} | |
288 | [@b{-O}] | |
252b5132 RH |
289 | @end ifset |
290 | @ifset D30V | |
a4fb0134 SC |
291 | |
292 | @emph{Target D30V options:} | |
293 | [@b{-O}|@b{-n}|@b{-N}] | |
252b5132 RH |
294 | @end ifset |
295 | @ifset H8 | |
6fd4f6cc DD |
296 | |
297 | @emph{Target H8/300 options:} | |
298 | [-h-tick-hex] | |
252b5132 RH |
299 | @end ifset |
300 | @ifset HPPA | |
301 | @c HPPA has no machine-dependent assembler options (yet). | |
302 | @end ifset | |
a4fb0134 SC |
303 | @ifset I80386 |
304 | ||
305 | @emph{Target i386 options:} | |
12b55ccc | 306 | [@b{--32}|@b{--64}] [@b{-n}] |
6305a203 | 307 | [@b{-march}=@var{CPU}[+@var{EXTENSION}@dots{}]] [@b{-mtune}=@var{CPU}] |
252b5132 RH |
308 | @end ifset |
309 | @ifset I960 | |
a4fb0134 SC |
310 | |
311 | @emph{Target i960 options:} | |
252b5132 | 312 | @c see md_parse_option in tc-i960.c |
a4fb0134 SC |
313 | [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}| |
314 | @b{-AKC}|@b{-AMC}] | |
315 | [@b{-b}] [@b{-no-relax}] | |
252b5132 | 316 | @end ifset |
587fe2b3 | 317 | @ifset IA64 |
a4fb0134 | 318 | |
9e32ca89 NC |
319 | @emph{Target IA-64 options:} |
320 | [@b{-mconstant-gp}|@b{-mauto-pic}] | |
321 | [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}] | |
322 | [@b{-mle}|@b{mbe}] | |
8c2fda1d | 323 | [@b{-mtune=itanium1}|@b{-mtune=itanium2}] |
970d6792 | 324 | [@b{-munwind-check=warning}|@b{-munwind-check=error}] |
91d777ee | 325 | [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}] |
9e32ca89 NC |
326 | [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}] |
327 | @end ifset | |
a40cbfa3 NC |
328 | @ifset IP2K |
329 | ||
330 | @emph{Target IP2K options:} | |
331 | [@b{-mip2022}|@b{-mip2022ext}] | |
332 | @end ifset | |
49f58d10 JB |
333 | @ifset M32C |
334 | ||
335 | @emph{Target M32C options:} | |
c54b5932 | 336 | [@b{-m32c}|@b{-m16c}] [-relax] [-h-tick-hex] |
49f58d10 | 337 | @end ifset |
587fe2b3 | 338 | @ifset M32R |
9e32ca89 | 339 | |
a4fb0134 SC |
340 | @emph{Target M32R options:} |
341 | [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}| | |
587fe2b3 | 342 | @b{--W[n]p}] |
ec694b89 | 343 | @end ifset |
252b5132 | 344 | @ifset M680X0 |
a4fb0134 SC |
345 | |
346 | @emph{Target M680X0 options:} | |
347 | [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}] | |
252b5132 | 348 | @end ifset |
60bcf0fa | 349 | @ifset M68HC11 |
a4fb0134 SC |
350 | |
351 | @emph{Target M68HC11 options:} | |
d01030e6 | 352 | [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}] |
2f904664 SC |
353 | [@b{-mshort}|@b{-mlong}] |
354 | [@b{-mshort-double}|@b{-mlong-double}] | |
1370e33d | 355 | [@b{--force-long-branches}] [@b{--short-branches}] |
a4fb0134 SC |
356 | [@b{--strict-direct-mode}] [@b{--print-insn-syntax}] |
357 | [@b{--print-opcodes}] [@b{--generate-example}] | |
358 | @end ifset | |
359 | @ifset MCORE | |
360 | ||
361 | @emph{Target MCORE options:} | |
362 | [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}] | |
363 | [@b{-mcpu=[210|340]}] | |
60bcf0fa | 364 | @end ifset |
252b5132 | 365 | @ifset MIPS |
a4fb0134 SC |
366 | |
367 | @emph{Target MIPS options:} | |
78849248 | 368 | [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]] |
437ee9d5 | 369 | [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}] |
0c000745 | 370 | [@b{-non_shared}] [@b{-xgot} [@b{-mvxworks-pic}] |
437ee9d5 TS |
371 | [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}] |
372 | [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}] | |
af7ee8bf | 373 | [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}] |
5f74bc13 | 374 | [@b{-mips64}] [@b{-mips64r2}] |
437ee9d5 TS |
375 | [@b{-construct-floats}] [@b{-no-construct-floats}] |
376 | [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}] | |
377 | [@b{-mfix7000}] [@b{-mno-fix7000}] | |
378 | [@b{-mips16}] [@b{-no-mips16}] | |
e16bfa71 | 379 | [@b{-msmartmips}] [@b{-mno-smartmips}] |
1f25f5d3 | 380 | [@b{-mips3d}] [@b{-no-mips3d}] |
deec1734 | 381 | [@b{-mdmx}] [@b{-no-mdmx}] |
2ef2b9ae | 382 | [@b{-mdsp}] [@b{-mno-dsp}] |
8b082fb1 | 383 | [@b{-mdspr2}] [@b{-mno-dspr2}] |
ef2e4d86 | 384 | [@b{-mmt}] [@b{-mno-mt}] |
ecb4347a | 385 | [@b{-mdebug}] [@b{-no-mdebug}] |
dcd410fe | 386 | [@b{-mpdr}] [@b{-mno-pdr}] |
3c3bdf30 NC |
387 | @end ifset |
388 | @ifset MMIX | |
a4fb0134 SC |
389 | |
390 | @emph{Target MMIX options:} | |
391 | [@b{--fixed-special-register-names}] [@b{--globalize-symbols}] | |
392 | [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}] | |
393 | [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}] | |
973eb340 | 394 | [@b{--linker-allocated-gregs}] |
a4fb0134 SC |
395 | @end ifset |
396 | @ifset PDP11 | |
397 | ||
398 | @emph{Target PDP11 options:} | |
399 | [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}] | |
400 | [@b{-m}@var{extension}|@b{-mno-}@var{extension}] | |
401 | [@b{-m}@var{cpu}] [@b{-m}@var{machine}] | |
402 | @end ifset | |
403 | @ifset PJ | |
404 | ||
405 | @emph{Target picoJava options:} | |
406 | [@b{-mb}|@b{-me}] | |
407 | @end ifset | |
408 | @ifset PPC | |
409 | ||
410 | @emph{Target PowerPC options:} | |
411 | [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}| | |
412 | @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}| | |
413 | @b{-mbooke32}|@b{-mbooke64}] | |
9b4e5766 | 414 | [@b{-mcom}|@b{-many}|@b{-maltivec}|@b{-mvsx}] [@b{-memb}] |
a4fb0134 SC |
415 | [@b{-mregnames}|@b{-mno-regnames}] |
416 | [@b{-mrelocatable}|@b{-mrelocatable-lib}] | |
417 | [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}] | |
418 | [@b{-msolaris}|@b{-mno-solaris}] | |
419 | @end ifset | |
420 | @ifset SPARC | |
421 | ||
422 | @emph{Target SPARC options:} | |
423 | @c The order here is important. See c-sparc.texi. | |
424 | [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite} | |
425 | @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}] | |
426 | [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}] | |
427 | [@b{-32}|@b{-64}] | |
428 | @end ifset | |
429 | @ifset TIC54X | |
430 | ||
431 | @emph{Target TIC54X options:} | |
432 | [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}] | |
433 | [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}] | |
434 | @end ifset | |
3c9b82ba NC |
435 | |
436 | @ifset Z80 | |
437 | ||
438 | @emph{Target Z80 options:} | |
439 | [@b{-z80}] [@b{-r800}] | |
440 | [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}] | |
441 | [@b{ -ignore-unportable-instructions}] [@b{-Wnup}] | |
442 | [@b{ -warn-undocumented-instructions}] [@b{-Wud}] | |
443 | [@b{ -warn-unportable-instructions}] [@b{-Wup}] | |
444 | [@b{ -forbid-undocumented-instructions}] [@b{-Fud}] | |
445 | [@b{ -forbid-unportable-instructions}] [@b{-Fup}] | |
446 | @end ifset | |
447 | ||
a4fb0134 SC |
448 | @ifset Z8000 |
449 | @c Z8000 has no machine-dependent assembler options | |
252b5132 | 450 | @end ifset |
e0001a05 NC |
451 | @ifset XTENSA |
452 | ||
453 | @emph{Target Xtensa options:} | |
43cd72b9 | 454 | [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}] |
e0001a05 | 455 | [@b{--[no-]target-align}] [@b{--[no-]longcalls}] |
43cd72b9 | 456 | [@b{--[no-]transform}] |
9456465c | 457 | [@b{--rename-section} @var{oldname}=@var{newname}] |
e0001a05 | 458 | @end ifset |
0285c67d | 459 | @c man end |
252b5132 RH |
460 | @end smallexample |
461 | ||
0285c67d NC |
462 | @c man begin OPTIONS |
463 | ||
a4fb0134 | 464 | @table @gcctabopt |
38fc1cb1 | 465 | @include at-file.texi |
a0b7da79 | 466 | |
83f10cb2 | 467 | @item -a[cdghlmns] |
252b5132 RH |
468 | Turn on listings, in any of a variety of ways: |
469 | ||
a4fb0134 | 470 | @table @gcctabopt |
252b5132 RH |
471 | @item -ac |
472 | omit false conditionals | |
473 | ||
474 | @item -ad | |
475 | omit debugging directives | |
476 | ||
83f10cb2 NC |
477 | @item -ag |
478 | include general information, like @value{AS} version and options passed | |
479 | ||
252b5132 RH |
480 | @item -ah |
481 | include high-level source | |
482 | ||
483 | @item -al | |
484 | include assembly | |
485 | ||
486 | @item -am | |
487 | include macro expansions | |
488 | ||
489 | @item -an | |
490 | omit forms processing | |
491 | ||
492 | @item -as | |
493 | include symbols | |
494 | ||
495 | @item =file | |
496 | set the name of the listing file | |
497 | @end table | |
498 | ||
499 | You may combine these options; for example, use @samp{-aln} for assembly | |
500 | listing without forms processing. The @samp{=file} option, if used, must be | |
501 | the last one. By itself, @samp{-a} defaults to @samp{-ahls}. | |
502 | ||
caa32fe5 | 503 | @item --alternate |
96e9638b BW |
504 | Begin in alternate macro mode. |
505 | @ifclear man | |
506 | @xref{Altmacro,,@code{.altmacro}}. | |
507 | @end ifclear | |
caa32fe5 | 508 | |
252b5132 RH |
509 | @item -D |
510 | Ignored. This option is accepted for script compatibility with calls to | |
511 | other assemblers. | |
512 | ||
3d6b762c JM |
513 | @item --debug-prefix-map @var{old}=@var{new} |
514 | When assembling files in directory @file{@var{old}}, record debugging | |
515 | information describing them as in @file{@var{new}} instead. | |
516 | ||
252b5132 RH |
517 | @item --defsym @var{sym}=@var{value} |
518 | Define the symbol @var{sym} to be @var{value} before assembling the input file. | |
519 | @var{value} must be an integer constant. As in C, a leading @samp{0x} | |
bf083c64 NC |
520 | indicates a hexadecimal value, and a leading @samp{0} indicates an octal |
521 | value. The value of the symbol can be overridden inside a source file via the | |
522 | use of a @code{.set} pseudo-op. | |
252b5132 RH |
523 | |
524 | @item -f | |
525 | ``fast''---skip whitespace and comment preprocessing (assume source is | |
526 | compiler output). | |
527 | ||
329e276d NC |
528 | @item -g |
529 | @itemx --gen-debug | |
530 | Generate debugging information for each assembler source line using whichever | |
531 | debug format is preferred by the target. This currently means either STABS, | |
532 | ECOFF or DWARF2. | |
533 | ||
252b5132 RH |
534 | @item --gstabs |
535 | Generate stabs debugging information for each assembler line. This | |
536 | may help debugging assembler code, if the debugger can handle it. | |
537 | ||
05da4302 NC |
538 | @item --gstabs+ |
539 | Generate stabs debugging information for each assembler line, with GNU | |
540 | extensions that probably only gdb can handle, and that could make other | |
541 | debuggers crash or refuse to read your program. This | |
542 | may help debugging assembler code. Currently the only GNU extension is | |
543 | the location of the current working directory at assembling time. | |
544 | ||
329e276d | 545 | @item --gdwarf-2 |
cdf82bcf | 546 | Generate DWARF2 debugging information for each assembler line. This |
c1253627 | 547 | may help debugging assembler code, if the debugger can handle it. Note---this |
85a39694 | 548 | option is only supported by some targets, not all of them. |
cdf82bcf | 549 | |
252b5132 RH |
550 | @item --help |
551 | Print a summary of the command line options and exit. | |
552 | ||
ea20a7da CC |
553 | @item --target-help |
554 | Print a summary of all target specific options and exit. | |
555 | ||
252b5132 RH |
556 | @item -I @var{dir} |
557 | Add directory @var{dir} to the search list for @code{.include} directives. | |
558 | ||
559 | @item -J | |
560 | Don't warn about signed overflow. | |
561 | ||
562 | @item -K | |
563 | @ifclear DIFF-TBL-KLUGE | |
564 | This option is accepted but has no effect on the @value{TARGET} family. | |
565 | @end ifclear | |
566 | @ifset DIFF-TBL-KLUGE | |
567 | Issue warnings when difference tables altered for long displacements. | |
568 | @end ifset | |
569 | ||
570 | @item -L | |
571 | @itemx --keep-locals | |
ba83aca1 BW |
572 | Keep (in the symbol table) local symbols. These symbols start with |
573 | system-specific local label prefixes, typically @samp{.L} for ELF systems | |
574 | or @samp{L} for traditional a.out systems. | |
575 | @ifclear man | |
576 | @xref{Symbol Names}. | |
577 | @end ifclear | |
252b5132 | 578 | |
c3a27914 NC |
579 | @item --listing-lhs-width=@var{number} |
580 | Set the maximum width, in words, of the output data column for an assembler | |
581 | listing to @var{number}. | |
582 | ||
583 | @item --listing-lhs-width2=@var{number} | |
584 | Set the maximum width, in words, of the output data column for continuation | |
585 | lines in an assembler listing to @var{number}. | |
586 | ||
587 | @item --listing-rhs-width=@var{number} | |
588 | Set the maximum width of an input source line, as displayed in a listing, to | |
589 | @var{number} bytes. | |
590 | ||
591 | @item --listing-cont-lines=@var{number} | |
592 | Set the maximum number of lines printed in a listing for a single line of input | |
593 | to @var{number} + 1. | |
594 | ||
252b5132 | 595 | @item -o @var{objfile} |
a4fb0134 | 596 | Name the object-file output from @command{@value{AS}} @var{objfile}. |
252b5132 RH |
597 | |
598 | @item -R | |
599 | Fold the data section into the text section. | |
600 | ||
4bdd3565 NC |
601 | @kindex --hash-size=@var{number} |
602 | Set the default size of GAS's hash tables to a prime number close to | |
603 | @var{number}. Increasing this value can reduce the length of time it takes the | |
604 | assembler to perform its tasks, at the expense of increasing the assembler's | |
605 | memory requirements. Similarly reducing this value can reduce the memory | |
606 | requirements at the expense of speed. | |
607 | ||
608 | @item --reduce-memory-overheads | |
609 | This option reduces GAS's memory requirements, at the expense of making the | |
610 | assembly processes slower. Currently this switch is a synonym for | |
611 | @samp{--hash-size=4051}, but in the future it may have other effects as well. | |
612 | ||
252b5132 RH |
613 | @item --statistics |
614 | Print the maximum space (in bytes) and total time (in seconds) used by | |
615 | assembly. | |
616 | ||
617 | @item --strip-local-absolute | |
618 | Remove local absolute symbols from the outgoing symbol table. | |
619 | ||
620 | @item -v | |
621 | @itemx -version | |
a4fb0134 | 622 | Print the @command{as} version. |
252b5132 RH |
623 | |
624 | @item --version | |
a4fb0134 | 625 | Print the @command{as} version and exit. |
252b5132 RH |
626 | |
627 | @item -W | |
2bdd6cf5 | 628 | @itemx --no-warn |
252b5132 RH |
629 | Suppress warning messages. |
630 | ||
2bdd6cf5 GK |
631 | @item --fatal-warnings |
632 | Treat warnings as errors. | |
633 | ||
634 | @item --warn | |
635 | Don't suppress warning messages or treat them as errors. | |
636 | ||
252b5132 RH |
637 | @item -w |
638 | Ignored. | |
639 | ||
640 | @item -x | |
641 | Ignored. | |
642 | ||
643 | @item -Z | |
644 | Generate an object file even after errors. | |
645 | ||
646 | @item -- | @var{files} @dots{} | |
647 | Standard input, or source files to assemble. | |
648 | ||
649 | @end table | |
650 | ||
651 | @ifset ARC | |
652 | The following options are available when @value{AS} is configured for | |
653 | an ARC processor. | |
654 | ||
a4fb0134 | 655 | @table @gcctabopt |
0d2bcfaf NC |
656 | @item -marc[5|6|7|8] |
657 | This option selects the core processor variant. | |
658 | @item -EB | -EL | |
659 | Select either big-endian (-EB) or little-endian (-EL) output. | |
252b5132 RH |
660 | @end table |
661 | @end ifset | |
662 | ||
663 | @ifset ARM | |
664 | The following options are available when @value{AS} is configured for the ARM | |
665 | processor family. | |
666 | ||
a4fb0134 | 667 | @table @gcctabopt |
92081f48 | 668 | @item -mcpu=@var{processor}[+@var{extension}@dots{}] |
cdf82bcf | 669 | Specify which ARM processor variant is the target. |
92081f48 | 670 | @item -march=@var{architecture}[+@var{extension}@dots{}] |
cdf82bcf | 671 | Specify which ARM architecture variant is used by the target. |
03b1477f | 672 | @item -mfpu=@var{floating-point-format} |
a349d9dd | 673 | Select which Floating Point architecture is the target. |
33a392fb PB |
674 | @item -mfloat-abi=@var{abi} |
675 | Select which floating point ABI is in use. | |
03b1477f RE |
676 | @item -mthumb |
677 | Enable Thumb only instruction decoding. | |
7f266840 | 678 | @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant |
252b5132 RH |
679 | Select which procedure calling convention is in use. |
680 | @item -EB | -EL | |
681 | Select either big-endian (-EB) or little-endian (-EL) output. | |
cdf82bcf NC |
682 | @item -mthumb-interwork |
683 | Specify that the code has been generated with interworking between Thumb and | |
684 | ARM code in mind. | |
685 | @item -k | |
686 | Specify that PIC code has been generated. | |
252b5132 RH |
687 | @end table |
688 | @end ifset | |
689 | ||
328eb32e HPN |
690 | @ifset CRIS |
691 | See the info pages for documentation of the CRIS-specific options. | |
692 | @end ifset | |
693 | ||
252b5132 RH |
694 | @ifset D10V |
695 | The following options are available when @value{AS} is configured for | |
696 | a D10V processor. | |
a4fb0134 | 697 | @table @gcctabopt |
252b5132 RH |
698 | @cindex D10V optimization |
699 | @cindex optimization, D10V | |
700 | @item -O | |
701 | Optimize output by parallelizing instructions. | |
702 | @end table | |
703 | @end ifset | |
704 | ||
705 | @ifset D30V | |
706 | The following options are available when @value{AS} is configured for a D30V | |
707 | processor. | |
a4fb0134 | 708 | @table @gcctabopt |
252b5132 RH |
709 | @cindex D30V optimization |
710 | @cindex optimization, D30V | |
711 | @item -O | |
712 | Optimize output by parallelizing instructions. | |
713 | ||
714 | @cindex D30V nops | |
715 | @item -n | |
716 | Warn when nops are generated. | |
717 | ||
718 | @cindex D30V nops after 32-bit multiply | |
719 | @item -N | |
720 | Warn when a nop after a 32-bit multiply instruction is generated. | |
721 | @end table | |
722 | @end ifset | |
723 | ||
724 | @ifset I960 | |
725 | The following options are available when @value{AS} is configured for the | |
726 | Intel 80960 processor. | |
727 | ||
a4fb0134 | 728 | @table @gcctabopt |
252b5132 RH |
729 | @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC |
730 | Specify which variant of the 960 architecture is the target. | |
731 | ||
732 | @item -b | |
733 | Add code to collect statistics about branches taken. | |
734 | ||
735 | @item -no-relax | |
736 | Do not alter compare-and-branch instructions for long displacements; | |
737 | error if necessary. | |
738 | ||
739 | @end table | |
740 | @end ifset | |
741 | ||
a40cbfa3 NC |
742 | @ifset IP2K |
743 | The following options are available when @value{AS} is configured for the | |
ec88d317 | 744 | Ubicom IP2K series. |
a40cbfa3 NC |
745 | |
746 | @table @gcctabopt | |
747 | ||
748 | @item -mip2022ext | |
749 | Specifies that the extended IP2022 instructions are allowed. | |
750 | ||
751 | @item -mip2022 | |
8dfa0188 | 752 | Restores the default behaviour, which restricts the permitted instructions to |
a40cbfa3 NC |
753 | just the basic IP2022 ones. |
754 | ||
755 | @end table | |
756 | @end ifset | |
757 | ||
49f58d10 JB |
758 | @ifset M32C |
759 | The following options are available when @value{AS} is configured for the | |
760 | Renesas M32C and M16C processors. | |
761 | ||
762 | @table @gcctabopt | |
763 | ||
764 | @item -m32c | |
765 | Assemble M32C instructions. | |
766 | ||
767 | @item -m16c | |
768 | Assemble M16C instructions (the default). | |
769 | ||
c54b5932 DD |
770 | @item -relax |
771 | Enable support for link-time relaxations. | |
772 | ||
773 | @item -h-tick-hex | |
774 | Support H'00 style hex constants in addition to 0x00 style. | |
775 | ||
49f58d10 JB |
776 | @end table |
777 | @end ifset | |
778 | ||
ec694b89 NC |
779 | @ifset M32R |
780 | The following options are available when @value{AS} is configured for the | |
26597c86 | 781 | Renesas M32R (formerly Mitsubishi M32R) series. |
ec694b89 | 782 | |
a4fb0134 | 783 | @table @gcctabopt |
ec694b89 NC |
784 | |
785 | @item --m32rx | |
786 | Specify which processor in the M32R family is the target. The default | |
787 | is normally the M32R, but this option changes it to the M32RX. | |
788 | ||
789 | @item --warn-explicit-parallel-conflicts or --Wp | |
790 | Produce warning messages when questionable parallel constructs are | |
791 | encountered. | |
792 | ||
793 | @item --no-warn-explicit-parallel-conflicts or --Wnp | |
794 | Do not produce warning messages when questionable parallel constructs are | |
795 | encountered. | |
796 | ||
797 | @end table | |
798 | @end ifset | |
252b5132 RH |
799 | |
800 | @ifset M680X0 | |
801 | The following options are available when @value{AS} is configured for the | |
802 | Motorola 68000 series. | |
803 | ||
a4fb0134 | 804 | @table @gcctabopt |
252b5132 RH |
805 | |
806 | @item -l | |
807 | Shorten references to undefined symbols, to one word instead of two. | |
808 | ||
0285c67d NC |
809 | @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 |
810 | @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332 | |
811 | @itemx | -m68333 | -m68340 | -mcpu32 | -m5200 | |
252b5132 RH |
812 | Specify what processor in the 68000 family is the target. The default |
813 | is normally the 68020, but this can be changed at configuration time. | |
814 | ||
815 | @item -m68881 | -m68882 | -mno-68881 | -mno-68882 | |
816 | The target machine does (or does not) have a floating-point coprocessor. | |
817 | The default is to assume a coprocessor for 68020, 68030, and cpu32. Although | |
818 | the basic 68000 is not compatible with the 68881, a combination of the | |
819 | two can be specified, since it's possible to do emulation of the | |
820 | coprocessor instructions with the main processor. | |
821 | ||
822 | @item -m68851 | -mno-68851 | |
823 | The target machine does (or does not) have a memory-management | |
824 | unit coprocessor. The default is to assume an MMU for 68020 and up. | |
825 | ||
826 | @end table | |
827 | @end ifset | |
828 | ||
e135f41b NC |
829 | @ifset PDP11 |
830 | ||
831 | For details about the PDP-11 machine dependent features options, | |
832 | see @ref{PDP-11-Options}. | |
833 | ||
a4fb0134 | 834 | @table @gcctabopt |
e135f41b NC |
835 | @item -mpic | -mno-pic |
836 | Generate position-independent (or position-dependent) code. The | |
a4fb0134 | 837 | default is @option{-mpic}. |
e135f41b NC |
838 | |
839 | @item -mall | |
840 | @itemx -mall-extensions | |
841 | Enable all instruction set extensions. This is the default. | |
842 | ||
843 | @item -mno-extensions | |
844 | Disable all instruction set extensions. | |
845 | ||
846 | @item -m@var{extension} | -mno-@var{extension} | |
847 | Enable (or disable) a particular instruction set extension. | |
848 | ||
849 | @item -m@var{cpu} | |
850 | Enable the instruction set extensions supported by a particular CPU, and | |
851 | disable all other extensions. | |
852 | ||
853 | @item -m@var{machine} | |
854 | Enable the instruction set extensions supported by a particular machine | |
855 | model, and disable all other extensions. | |
856 | @end table | |
857 | ||
858 | @end ifset | |
859 | ||
041dd5a9 ILT |
860 | @ifset PJ |
861 | The following options are available when @value{AS} is configured for | |
862 | a picoJava processor. | |
863 | ||
a4fb0134 | 864 | @table @gcctabopt |
041dd5a9 ILT |
865 | |
866 | @cindex PJ endianness | |
867 | @cindex endianness, PJ | |
868 | @cindex big endian output, PJ | |
869 | @item -mb | |
870 | Generate ``big endian'' format output. | |
871 | ||
872 | @cindex little endian output, PJ | |
873 | @item -ml | |
874 | Generate ``little endian'' format output. | |
875 | ||
876 | @end table | |
877 | @end ifset | |
878 | ||
60bcf0fa NC |
879 | @ifset M68HC11 |
880 | The following options are available when @value{AS} is configured for the | |
881 | Motorola 68HC11 or 68HC12 series. | |
882 | ||
a4fb0134 | 883 | @table @gcctabopt |
60bcf0fa | 884 | |
d01030e6 | 885 | @item -m68hc11 | -m68hc12 | -m68hcs12 |
60bcf0fa NC |
886 | Specify what processor is the target. The default is |
887 | defined by the configuration option when building the assembler. | |
888 | ||
2f904664 SC |
889 | @item -mshort |
890 | Specify to use the 16-bit integer ABI. | |
891 | ||
892 | @item -mlong | |
893 | Specify to use the 32-bit integer ABI. | |
894 | ||
895 | @item -mshort-double | |
896 | Specify to use the 32-bit double ABI. | |
897 | ||
898 | @item -mlong-double | |
899 | Specify to use the 64-bit double ABI. | |
900 | ||
1370e33d | 901 | @item --force-long-branches |
60bcf0fa NC |
902 | Relative branches are turned into absolute ones. This concerns |
903 | conditional branches, unconditional branches and branches to a | |
904 | sub routine. | |
905 | ||
1370e33d NC |
906 | @item -S | --short-branches |
907 | Do not turn relative branches into absolute ones | |
60bcf0fa NC |
908 | when the offset is out of range. |
909 | ||
910 | @item --strict-direct-mode | |
911 | Do not turn the direct addressing mode into extended addressing mode | |
912 | when the instruction does not support direct addressing mode. | |
913 | ||
914 | @item --print-insn-syntax | |
915 | Print the syntax of instruction in case of error. | |
916 | ||
917 | @item --print-opcodes | |
918 | print the list of instructions with syntax and then exit. | |
919 | ||
920 | @item --generate-example | |
921 | print an example of instruction for each possible instruction and then exit. | |
a4fb0134 | 922 | This option is only useful for testing @command{@value{AS}}. |
60bcf0fa NC |
923 | |
924 | @end table | |
925 | @end ifset | |
926 | ||
252b5132 | 927 | @ifset SPARC |
a4fb0134 | 928 | The following options are available when @command{@value{AS}} is configured |
252b5132 RH |
929 | for the SPARC architecture: |
930 | ||
a4fb0134 | 931 | @table @gcctabopt |
252b5132 RH |
932 | @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite |
933 | @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a | |
934 | Explicitly select a variant of the SPARC architecture. | |
935 | ||
936 | @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment. | |
937 | @samp{-Av9} and @samp{-Av9a} select a 64 bit environment. | |
938 | ||
939 | @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with | |
940 | UltraSPARC extensions. | |
941 | ||
942 | @item -xarch=v8plus | -xarch=v8plusa | |
943 | For compatibility with the Solaris v9 assembler. These options are | |
944 | equivalent to -Av8plus and -Av8plusa, respectively. | |
945 | ||
946 | @item -bump | |
947 | Warn when the assembler switches to another architecture. | |
948 | @end table | |
949 | @end ifset | |
950 | ||
39bec121 TW |
951 | @ifset TIC54X |
952 | The following options are available when @value{AS} is configured for the 'c54x | |
953 | architecture. | |
954 | ||
a4fb0134 | 955 | @table @gcctabopt |
39bec121 TW |
956 | @item -mfar-mode |
957 | Enable extended addressing mode. All addresses and relocations will assume | |
958 | extended addressing (usually 23 bits). | |
959 | @item -mcpu=@var{CPU_VERSION} | |
960 | Sets the CPU version being compiled for. | |
961 | @item -merrors-to-file @var{FILENAME} | |
962 | Redirect error output to a file, for broken systems which don't support such | |
963 | behaviour in the shell. | |
964 | @end table | |
965 | @end ifset | |
966 | ||
252b5132 RH |
967 | @ifset MIPS |
968 | The following options are available when @value{AS} is configured for | |
437ee9d5 | 969 | a @sc{mips} processor. |
252b5132 | 970 | |
a4fb0134 | 971 | @table @gcctabopt |
252b5132 RH |
972 | @item -G @var{num} |
973 | This option sets the largest size of an object that can be referenced | |
974 | implicitly with the @code{gp} register. It is only accepted for targets that | |
975 | use ECOFF format, such as a DECstation running Ultrix. The default value is 8. | |
976 | ||
977 | @cindex MIPS endianness | |
978 | @cindex endianness, MIPS | |
979 | @cindex big endian output, MIPS | |
980 | @item -EB | |
981 | Generate ``big endian'' format output. | |
982 | ||
983 | @cindex little endian output, MIPS | |
984 | @item -EL | |
985 | Generate ``little endian'' format output. | |
986 | ||
987 | @cindex MIPS ISA | |
988 | @item -mips1 | |
989 | @itemx -mips2 | |
990 | @itemx -mips3 | |
e7af610e | 991 | @itemx -mips4 |
437ee9d5 | 992 | @itemx -mips5 |
e7af610e | 993 | @itemx -mips32 |
af7ee8bf | 994 | @itemx -mips32r2 |
4058e45f | 995 | @itemx -mips64 |
5f74bc13 | 996 | @itemx -mips64r2 |
437ee9d5 TS |
997 | Generate code for a particular @sc{mips} Instruction Set Architecture level. |
998 | @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an | |
999 | alias for @samp{-march=r6000}, @samp{-mips3} is an alias for | |
1000 | @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}. | |
5f74bc13 CD |
1001 | @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and |
1002 | @samp{-mips64r2} | |
af7ee8bf | 1003 | correspond to generic |
5f74bc13 CD |
1004 | @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64}, |
1005 | and @samp{MIPS64 Release 2} | |
1006 | ISA processors, respectively. | |
437ee9d5 TS |
1007 | |
1008 | @item -march=@var{CPU} | |
1009 | Generate code for a particular @sc{mips} cpu. | |
1010 | ||
1011 | @item -mtune=@var{cpu} | |
1012 | Schedule and tune for a particular @sc{mips} cpu. | |
1013 | ||
1014 | @item -mfix7000 | |
1015 | @itemx -mno-fix7000 | |
1016 | Cause nops to be inserted if the read of the destination register | |
1017 | of an mfhi or mflo instruction occurs in the following two instructions. | |
1018 | ||
ecb4347a DJ |
1019 | @item -mdebug |
1020 | @itemx -no-mdebug | |
1021 | Cause stabs-style debugging output to go into an ECOFF-style .mdebug | |
1022 | section instead of the standard ELF .stabs sections. | |
1023 | ||
dcd410fe RO |
1024 | @item -mpdr |
1025 | @itemx -mno-pdr | |
1026 | Control generation of @code{.pdr} sections. | |
1027 | ||
437ee9d5 TS |
1028 | @item -mgp32 |
1029 | @itemx -mfp32 | |
1030 | The register sizes are normally inferred from the ISA and ABI, but these | |
1031 | flags force a certain group of registers to be treated as 32 bits wide at | |
1032 | all times. @samp{-mgp32} controls the size of general-purpose registers | |
1033 | and @samp{-mfp32} controls the size of floating-point registers. | |
1034 | ||
1035 | @item -mips16 | |
1036 | @itemx -no-mips16 | |
1037 | Generate code for the MIPS 16 processor. This is equivalent to putting | |
1038 | @code{.set mips16} at the start of the assembly file. @samp{-no-mips16} | |
1039 | turns off this option. | |
252b5132 | 1040 | |
e16bfa71 TS |
1041 | @item -msmartmips |
1042 | @itemx -mno-smartmips | |
1043 | Enables the SmartMIPS extension to the MIPS32 instruction set. This is | |
1044 | equivalent to putting @code{.set smartmips} at the start of the assembly file. | |
1045 | @samp{-mno-smartmips} turns off this option. | |
1046 | ||
1f25f5d3 CD |
1047 | @item -mips3d |
1048 | @itemx -no-mips3d | |
1049 | Generate code for the MIPS-3D Application Specific Extension. | |
1050 | This tells the assembler to accept MIPS-3D instructions. | |
1051 | @samp{-no-mips3d} turns off this option. | |
1052 | ||
deec1734 CD |
1053 | @item -mdmx |
1054 | @itemx -no-mdmx | |
1055 | Generate code for the MDMX Application Specific Extension. | |
1056 | This tells the assembler to accept MDMX instructions. | |
1057 | @samp{-no-mdmx} turns off this option. | |
1058 | ||
2ef2b9ae CF |
1059 | @item -mdsp |
1060 | @itemx -mno-dsp | |
8b082fb1 TS |
1061 | Generate code for the DSP Release 1 Application Specific Extension. |
1062 | This tells the assembler to accept DSP Release 1 instructions. | |
2ef2b9ae CF |
1063 | @samp{-mno-dsp} turns off this option. |
1064 | ||
8b082fb1 TS |
1065 | @item -mdspr2 |
1066 | @itemx -mno-dspr2 | |
1067 | Generate code for the DSP Release 2 Application Specific Extension. | |
1068 | This option implies -mdsp. | |
1069 | This tells the assembler to accept DSP Release 2 instructions. | |
1070 | @samp{-mno-dspr2} turns off this option. | |
1071 | ||
ef2e4d86 CF |
1072 | @item -mmt |
1073 | @itemx -mno-mt | |
1074 | Generate code for the MT Application Specific Extension. | |
1075 | This tells the assembler to accept MT instructions. | |
1076 | @samp{-mno-mt} turns off this option. | |
1077 | ||
437ee9d5 TS |
1078 | @item --construct-floats |
1079 | @itemx --no-construct-floats | |
1080 | The @samp{--no-construct-floats} option disables the construction of | |
1081 | double width floating point constants by loading the two halves of the | |
1082 | value into the two single width floating point registers that make up | |
1083 | the double width register. By default @samp{--construct-floats} is | |
1084 | selected, allowing construction of these floating point constants. | |
252b5132 RH |
1085 | |
1086 | @cindex emulation | |
1087 | @item --emulation=@var{name} | |
a4fb0134 | 1088 | This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured |
252b5132 RH |
1089 | for some other target, in all respects, including output format (choosing |
1090 | between ELF and ECOFF only), handling of pseudo-opcodes which may generate | |
1091 | debugging information or store symbol table information, and default | |
1092 | endianness. The available configuration names are: @samp{mipsecoff}, | |
1093 | @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf}, | |
1094 | @samp{mipsbelf}. The first two do not alter the default endianness from that | |
1095 | of the primary target for which the assembler was configured; the others change | |
1096 | the default to little- or big-endian as indicated by the @samp{b} or @samp{l} | |
1097 | in the name. Using @samp{-EB} or @samp{-EL} will override the endianness | |
1098 | selection in any case. | |
1099 | ||
1100 | This option is currently supported only when the primary target | |
437ee9d5 | 1101 | @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target. |
252b5132 RH |
1102 | Furthermore, the primary target or others specified with |
1103 | @samp{--enable-targets=@dots{}} at configuration time must include support for | |
1104 | the other format, if both are to be available. For example, the Irix 5 | |
1105 | configuration includes support for both. | |
1106 | ||
1107 | Eventually, this option will support more configurations, with more | |
1108 | fine-grained control over the assembler's behavior, and will be supported for | |
1109 | more processors. | |
1110 | ||
1111 | @item -nocpp | |
a4fb0134 | 1112 | @command{@value{AS}} ignores this option. It is accepted for compatibility with |
252b5132 RH |
1113 | the native tools. |
1114 | ||
252b5132 RH |
1115 | @item --trap |
1116 | @itemx --no-trap | |
1117 | @itemx --break | |
1118 | @itemx --no-break | |
1119 | Control how to deal with multiplication overflow and division by zero. | |
1120 | @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception | |
1121 | (and only work for Instruction Set Architecture level 2 and higher); | |
1122 | @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a | |
1123 | break exception. | |
63486801 L |
1124 | |
1125 | @item -n | |
a4fb0134 | 1126 | When this option is used, @command{@value{AS}} will issue a warning every |
63486801 | 1127 | time it generates a nop instruction from a macro. |
252b5132 RH |
1128 | @end table |
1129 | @end ifset | |
1130 | ||
1131 | @ifset MCORE | |
1132 | The following options are available when @value{AS} is configured for | |
1133 | an MCore processor. | |
1134 | ||
a4fb0134 | 1135 | @table @gcctabopt |
252b5132 RH |
1136 | @item -jsri2bsr |
1137 | @itemx -nojsri2bsr | |
1138 | Enable or disable the JSRI to BSR transformation. By default this is enabled. | |
1139 | The command line option @samp{-nojsri2bsr} can be used to disable it. | |
1140 | ||
1141 | @item -sifilter | |
1142 | @itemx -nosifilter | |
1143 | Enable or disable the silicon filter behaviour. By default this is disabled. | |
a349d9dd | 1144 | The default can be overridden by the @samp{-sifilter} command line option. |
252b5132 RH |
1145 | |
1146 | @item -relax | |
1147 | Alter jump instructions for long displacements. | |
1148 | ||
ec694b89 NC |
1149 | @item -mcpu=[210|340] |
1150 | Select the cpu type on the target hardware. This controls which instructions | |
1151 | can be assembled. | |
1152 | ||
1153 | @item -EB | |
1154 | Assemble for a big endian target. | |
1155 | ||
1156 | @item -EL | |
1157 | Assemble for a little endian target. | |
252b5132 RH |
1158 | |
1159 | @end table | |
1160 | @end ifset | |
1161 | ||
3c3bdf30 NC |
1162 | @ifset MMIX |
1163 | See the info pages for documentation of the MMIX-specific options. | |
1164 | @end ifset | |
1165 | ||
e0001a05 NC |
1166 | @ifset XTENSA |
1167 | The following options are available when @value{AS} is configured for | |
1168 | an Xtensa processor. | |
1169 | ||
1170 | @table @gcctabopt | |
e0001a05 NC |
1171 | @item --text-section-literals | --no-text-section-literals |
1172 | With @option{--text-@-section-@-literals}, literal pools are interspersed | |
1173 | in the text section. The default is | |
1174 | @option{--no-@-text-@-section-@-literals}, which places literals in a | |
43cd72b9 BW |
1175 | separate section in the output file. These options only affect literals |
1176 | referenced via PC-relative @code{L32R} instructions; literals for | |
1177 | absolute mode @code{L32R} instructions are handled separately. | |
1178 | ||
1179 | @item --absolute-literals | --no-absolute-literals | |
1180 | Indicate to the assembler whether @code{L32R} instructions use absolute | |
1181 | or PC-relative addressing. The default is to assume absolute addressing | |
1182 | if the Xtensa processor includes the absolute @code{L32R} addressing | |
1183 | option. Otherwise, only the PC-relative @code{L32R} mode can be used. | |
e0001a05 NC |
1184 | |
1185 | @item --target-align | --no-target-align | |
1186 | Enable or disable automatic alignment to reduce branch penalties at the | |
1187 | expense of some code density. The default is @option{--target-@-align}. | |
1188 | ||
1189 | @item --longcalls | --no-longcalls | |
1190 | Enable or disable transformation of call instructions to allow calls | |
1191 | across a greater range of addresses. The default is | |
1192 | @option{--no-@-longcalls}. | |
43cd72b9 BW |
1193 | |
1194 | @item --transform | --no-transform | |
1195 | Enable or disable all assembler transformations of Xtensa instructions. | |
1196 | The default is @option{--transform}; | |
1197 | @option{--no-transform} should be used only in the rare cases when the | |
1198 | instructions must be exactly as specified in the assembly source. | |
00e3c476 BW |
1199 | |
1200 | @item --rename-section @var{oldname}=@var{newname} | |
1201 | When generating output sections, rename the @var{oldname} section to | |
1202 | @var{newname}. | |
e0001a05 NC |
1203 | @end table |
1204 | @end ifset | |
1205 | ||
3c9b82ba NC |
1206 | @ifset Z80 |
1207 | The following options are available when @value{AS} is configured for | |
1208 | a Z80 family processor. | |
1209 | @table @gcctabopt | |
1210 | @item -z80 | |
1211 | Assemble for Z80 processor. | |
1212 | @item -r800 | |
1213 | Assemble for R800 processor. | |
1214 | @item -ignore-undocumented-instructions | |
1215 | @itemx -Wnud | |
1216 | Assemble undocumented Z80 instructions that also work on R800 without warning. | |
1217 | @item -ignore-unportable-instructions | |
1218 | @itemx -Wnup | |
1219 | Assemble all undocumented Z80 instructions without warning. | |
1220 | @item -warn-undocumented-instructions | |
1221 | @itemx -Wud | |
1222 | Issue a warning for undocumented Z80 instructions that also work on R800. | |
1223 | @item -warn-unportable-instructions | |
1224 | @itemx -Wup | |
b45619c0 | 1225 | Issue a warning for undocumented Z80 instructions that do not work on R800. |
3c9b82ba NC |
1226 | @item -forbid-undocumented-instructions |
1227 | @itemx -Fud | |
1228 | Treat all undocumented instructions as errors. | |
1229 | @item -forbid-unportable-instructions | |
1230 | @itemx -Fup | |
b45619c0 | 1231 | Treat undocumented Z80 instructions that do not work on R800 as errors. |
3c9b82ba NC |
1232 | @end table |
1233 | @end ifset | |
1234 | ||
0285c67d NC |
1235 | @c man end |
1236 | ||
252b5132 RH |
1237 | @menu |
1238 | * Manual:: Structure of this Manual | |
1239 | * GNU Assembler:: The GNU Assembler | |
1240 | * Object Formats:: Object File Formats | |
1241 | * Command Line:: Command Line | |
1242 | * Input Files:: Input Files | |
1243 | * Object:: Output (Object) File | |
1244 | * Errors:: Error and Warning Messages | |
1245 | @end menu | |
1246 | ||
1247 | @node Manual | |
1248 | @section Structure of this Manual | |
1249 | ||
1250 | @cindex manual, structure and purpose | |
1251 | This manual is intended to describe what you need to know to use | |
a4fb0134 | 1252 | @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including |
252b5132 | 1253 | notation for symbols, constants, and expressions; the directives that |
a4fb0134 | 1254 | @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}. |
252b5132 RH |
1255 | |
1256 | @ifclear GENERIC | |
1257 | We also cover special features in the @value{TARGET} | |
a4fb0134 | 1258 | configuration of @command{@value{AS}}, including assembler directives. |
252b5132 RH |
1259 | @end ifclear |
1260 | @ifset GENERIC | |
1261 | This manual also describes some of the machine-dependent features of | |
1262 | various flavors of the assembler. | |
1263 | @end ifset | |
1264 | ||
1265 | @cindex machine instructions (not covered) | |
1266 | On the other hand, this manual is @emph{not} intended as an introduction | |
1267 | to programming in assembly language---let alone programming in general! | |
1268 | In a similar vein, we make no attempt to introduce the machine | |
1269 | architecture; we do @emph{not} describe the instruction set, standard | |
1270 | mnemonics, registers or addressing modes that are standard to a | |
1271 | particular architecture. | |
1272 | @ifset GENERIC | |
1273 | You may want to consult the manufacturer's | |
1274 | machine architecture manual for this information. | |
1275 | @end ifset | |
1276 | @ifclear GENERIC | |
1277 | @ifset H8/300 | |
1278 | For information on the H8/300 machine instruction set, see @cite{H8/300 | |
c2dcd04e NC |
1279 | Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series |
1280 | Programming Manual} (Renesas). | |
252b5132 | 1281 | @end ifset |
252b5132 | 1282 | @ifset SH |
ef230218 JR |
1283 | For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set, |
1284 | see @cite{SH-Microcomputer User's Manual} (Renesas) or | |
1285 | @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and | |
1286 | @cite{SuperH (SH) 64-Bit RISC Series} (SuperH). | |
252b5132 RH |
1287 | @end ifset |
1288 | @ifset Z8000 | |
1289 | For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual} | |
1290 | @end ifset | |
1291 | @end ifclear | |
1292 | ||
1293 | @c I think this is premature---doc@cygnus.com, 17jan1991 | |
1294 | @ignore | |
1295 | Throughout this manual, we assume that you are running @dfn{GNU}, | |
1296 | the portable operating system from the @dfn{Free Software | |
1297 | Foundation, Inc.}. This restricts our attention to certain kinds of | |
1298 | computer (in particular, the kinds of computers that @sc{gnu} can run on); | |
1299 | once this assumption is granted examples and definitions need less | |
1300 | qualification. | |
1301 | ||
a4fb0134 | 1302 | @command{@value{AS}} is part of a team of programs that turn a high-level |
252b5132 RH |
1303 | human-readable series of instructions into a low-level |
1304 | computer-readable series of instructions. Different versions of | |
a4fb0134 | 1305 | @command{@value{AS}} are used for different kinds of computer. |
252b5132 RH |
1306 | @end ignore |
1307 | ||
1308 | @c There used to be a section "Terminology" here, which defined | |
1309 | @c "contents", "byte", "word", and "long". Defining "word" to any | |
1310 | @c particular size is confusing when the .word directive may generate 16 | |
1311 | @c bits on one machine and 32 bits on another; in general, for the user | |
1312 | @c version of this manual, none of these terms seem essential to define. | |
1313 | @c They were used very little even in the former draft of the manual; | |
1314 | @c this draft makes an effort to avoid them (except in names of | |
1315 | @c directives). | |
1316 | ||
1317 | @node GNU Assembler | |
1318 | @section The GNU Assembler | |
1319 | ||
0285c67d NC |
1320 | @c man begin DESCRIPTION |
1321 | ||
a4fb0134 | 1322 | @sc{gnu} @command{as} is really a family of assemblers. |
252b5132 | 1323 | @ifclear GENERIC |
a4fb0134 | 1324 | This manual describes @command{@value{AS}}, a member of that family which is |
252b5132 RH |
1325 | configured for the @value{TARGET} architectures. |
1326 | @end ifclear | |
1327 | If you use (or have used) the @sc{gnu} assembler on one architecture, you | |
1328 | should find a fairly similar environment when you use it on another | |
1329 | architecture. Each version has much in common with the others, | |
1330 | including object file formats, most assembler directives (often called | |
1331 | @dfn{pseudo-ops}) and assembler syntax.@refill | |
1332 | ||
1333 | @cindex purpose of @sc{gnu} assembler | |
a4fb0134 | 1334 | @command{@value{AS}} is primarily intended to assemble the output of the |
252b5132 | 1335 | @sc{gnu} C compiler @code{@value{GCC}} for use by the linker |
a4fb0134 | 1336 | @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}} |
252b5132 RH |
1337 | assemble correctly everything that other assemblers for the same |
1338 | machine would assemble. | |
1339 | @ifset VAX | |
1340 | Any exceptions are documented explicitly (@pxref{Machine Dependencies}). | |
1341 | @end ifset | |
1342 | @ifset M680X0 | |
1343 | @c This remark should appear in generic version of manual; assumption | |
1344 | @c here is that generic version sets M680x0. | |
a4fb0134 | 1345 | This doesn't mean @command{@value{AS}} always uses the same syntax as another |
252b5132 RH |
1346 | assembler for the same architecture; for example, we know of several |
1347 | incompatible versions of 680x0 assembly language syntax. | |
1348 | @end ifset | |
1349 | ||
0285c67d NC |
1350 | @c man end |
1351 | ||
a4fb0134 | 1352 | Unlike older assemblers, @command{@value{AS}} is designed to assemble a source |
252b5132 RH |
1353 | program in one pass of the source file. This has a subtle impact on the |
1354 | @kbd{.org} directive (@pxref{Org,,@code{.org}}). | |
1355 | ||
1356 | @node Object Formats | |
1357 | @section Object File Formats | |
1358 | ||
1359 | @cindex object file format | |
1360 | The @sc{gnu} assembler can be configured to produce several alternative | |
1361 | object file formats. For the most part, this does not affect how you | |
1362 | write assembly language programs; but directives for debugging symbols | |
1363 | are typically different in different file formats. @xref{Symbol | |
1364 | Attributes,,Symbol Attributes}. | |
1365 | @ifclear GENERIC | |
1366 | @ifclear MULTI-OBJ | |
c1253627 | 1367 | For the @value{TARGET} target, @command{@value{AS}} is configured to produce |
252b5132 RH |
1368 | @value{OBJ-NAME} format object files. |
1369 | @end ifclear | |
1370 | @c The following should exhaust all configs that set MULTI-OBJ, ideally | |
252b5132 | 1371 | @ifset I960 |
a4fb0134 | 1372 | On the @value{TARGET}, @command{@value{AS}} can be configured to produce either |
252b5132 RH |
1373 | @code{b.out} or COFF format object files. |
1374 | @end ifset | |
1375 | @ifset HPPA | |
a4fb0134 | 1376 | On the @value{TARGET}, @command{@value{AS}} can be configured to produce either |
252b5132 RH |
1377 | SOM or ELF format object files. |
1378 | @end ifset | |
1379 | @end ifclear | |
1380 | ||
1381 | @node Command Line | |
1382 | @section Command Line | |
1383 | ||
1384 | @cindex command line conventions | |
0285c67d | 1385 | |
a4fb0134 | 1386 | After the program name @command{@value{AS}}, the command line may contain |
252b5132 RH |
1387 | options and file names. Options may appear in any order, and may be |
1388 | before, after, or between file names. The order of file names is | |
1389 | significant. | |
1390 | ||
1391 | @cindex standard input, as input file | |
1392 | @kindex -- | |
1393 | @file{--} (two hyphens) by itself names the standard input file | |
a4fb0134 | 1394 | explicitly, as one of the files for @command{@value{AS}} to assemble. |
252b5132 RH |
1395 | |
1396 | @cindex options, command line | |
1397 | Except for @samp{--} any command line argument that begins with a | |
1398 | hyphen (@samp{-}) is an option. Each option changes the behavior of | |
a4fb0134 | 1399 | @command{@value{AS}}. No option changes the way another option works. An |
252b5132 RH |
1400 | option is a @samp{-} followed by one or more letters; the case of |
1401 | the letter is important. All options are optional. | |
1402 | ||
1403 | Some options expect exactly one file name to follow them. The file | |
1404 | name may either immediately follow the option's letter (compatible | |
1405 | with older assemblers) or it may be the next command argument (@sc{gnu} | |
1406 | standard). These two command lines are equivalent: | |
1407 | ||
1408 | @smallexample | |
1409 | @value{AS} -o my-object-file.o mumble.s | |
1410 | @value{AS} -omy-object-file.o mumble.s | |
1411 | @end smallexample | |
1412 | ||
1413 | @node Input Files | |
1414 | @section Input Files | |
1415 | ||
1416 | @cindex input | |
1417 | @cindex source program | |
1418 | @cindex files, input | |
1419 | We use the phrase @dfn{source program}, abbreviated @dfn{source}, to | |
a4fb0134 | 1420 | describe the program input to one run of @command{@value{AS}}. The program may |
252b5132 RH |
1421 | be in one or more files; how the source is partitioned into files |
1422 | doesn't change the meaning of the source. | |
1423 | ||
1424 | @c I added "con" prefix to "catenation" just to prove I can overcome my | |
1425 | @c APL training... doc@cygnus.com | |
1426 | The source program is a concatenation of the text in all the files, in the | |
1427 | order specified. | |
1428 | ||
0285c67d | 1429 | @c man begin DESCRIPTION |
a4fb0134 | 1430 | Each time you run @command{@value{AS}} it assembles exactly one source |
252b5132 RH |
1431 | program. The source program is made up of one or more files. |
1432 | (The standard input is also a file.) | |
1433 | ||
a4fb0134 | 1434 | You give @command{@value{AS}} a command line that has zero or more input file |
252b5132 RH |
1435 | names. The input files are read (from left file name to right). A |
1436 | command line argument (in any position) that has no special meaning | |
1437 | is taken to be an input file name. | |
1438 | ||
a4fb0134 SC |
1439 | If you give @command{@value{AS}} no file names it attempts to read one input file |
1440 | from the @command{@value{AS}} standard input, which is normally your terminal. You | |
1441 | may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program | |
252b5132 RH |
1442 | to assemble. |
1443 | ||
1444 | Use @samp{--} if you need to explicitly name the standard input file | |
1445 | in your command line. | |
1446 | ||
a4fb0134 | 1447 | If the source is empty, @command{@value{AS}} produces a small, empty object |
252b5132 RH |
1448 | file. |
1449 | ||
0285c67d NC |
1450 | @c man end |
1451 | ||
252b5132 RH |
1452 | @subheading Filenames and Line-numbers |
1453 | ||
1454 | @cindex input file linenumbers | |
1455 | @cindex line numbers, in input files | |
1456 | There are two ways of locating a line in the input file (or files) and | |
1457 | either may be used in reporting error messages. One way refers to a line | |
1458 | number in a physical file; the other refers to a line number in a | |
1459 | ``logical'' file. @xref{Errors, ,Error and Warning Messages}. | |
1460 | ||
1461 | @dfn{Physical files} are those files named in the command line given | |
a4fb0134 | 1462 | to @command{@value{AS}}. |
252b5132 RH |
1463 | |
1464 | @dfn{Logical files} are simply names declared explicitly by assembler | |
1465 | directives; they bear no relation to physical files. Logical file names help | |
a4fb0134 SC |
1466 | error messages reflect the original source file, when @command{@value{AS}} source |
1467 | is itself synthesized from other files. @command{@value{AS}} understands the | |
252b5132 RH |
1468 | @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also |
1469 | @ref{File,,@code{.file}}. | |
1470 | ||
1471 | @node Object | |
1472 | @section Output (Object) File | |
1473 | ||
1474 | @cindex object file | |
1475 | @cindex output file | |
1476 | @kindex a.out | |
1477 | @kindex .o | |
a4fb0134 | 1478 | Every time you run @command{@value{AS}} it produces an output file, which is |
252b5132 RH |
1479 | your assembly language program translated into numbers. This file |
1480 | is the object file. Its default name is | |
1481 | @ifclear BOUT | |
1482 | @code{a.out}. | |
1483 | @end ifclear | |
1484 | @ifset BOUT | |
1485 | @ifset GENERIC | |
1486 | @code{a.out}, or | |
1487 | @end ifset | |
a4fb0134 | 1488 | @code{b.out} when @command{@value{AS}} is configured for the Intel 80960. |
252b5132 | 1489 | @end ifset |
a4fb0134 | 1490 | You can give it another name by using the @option{-o} option. Conventionally, |
252b5132 RH |
1491 | object file names end with @file{.o}. The default name is used for historical |
1492 | reasons: older assemblers were capable of assembling self-contained programs | |
1493 | directly into a runnable program. (For some formats, this isn't currently | |
1494 | possible, but it can be done for the @code{a.out} format.) | |
1495 | ||
1496 | @cindex linker | |
1497 | @kindex ld | |
1498 | The object file is meant for input to the linker @code{@value{LD}}. It contains | |
1499 | assembled program code, information to help @code{@value{LD}} integrate | |
1500 | the assembled program into a runnable file, and (optionally) symbolic | |
1501 | information for the debugger. | |
1502 | ||
1503 | @c link above to some info file(s) like the description of a.out. | |
1504 | @c don't forget to describe @sc{gnu} info as well as Unix lossage. | |
1505 | ||
1506 | @node Errors | |
1507 | @section Error and Warning Messages | |
1508 | ||
0285c67d NC |
1509 | @c man begin DESCRIPTION |
1510 | ||
a349d9dd | 1511 | @cindex error messages |
252b5132 RH |
1512 | @cindex warning messages |
1513 | @cindex messages from assembler | |
a4fb0134 | 1514 | @command{@value{AS}} may write warnings and error messages to the standard error |
252b5132 | 1515 | file (usually your terminal). This should not happen when a compiler |
a4fb0134 SC |
1516 | runs @command{@value{AS}} automatically. Warnings report an assumption made so |
1517 | that @command{@value{AS}} could keep assembling a flawed program; errors report a | |
252b5132 RH |
1518 | grave problem that stops the assembly. |
1519 | ||
0285c67d NC |
1520 | @c man end |
1521 | ||
252b5132 RH |
1522 | @cindex format of warning messages |
1523 | Warning messages have the format | |
1524 | ||
1525 | @smallexample | |
1526 | file_name:@b{NNN}:Warning Message Text | |
1527 | @end smallexample | |
1528 | ||
1529 | @noindent | |
1530 | @cindex line numbers, in warnings/errors | |
1531 | (where @b{NNN} is a line number). If a logical file name has been given | |
1532 | (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of | |
1533 | the current input file is used. If a logical line number was given | |
1534 | @ifset GENERIC | |
1535 | (@pxref{Line,,@code{.line}}) | |
1536 | @end ifset | |
252b5132 RH |
1537 | then it is used to calculate the number printed, |
1538 | otherwise the actual line in the current source file is printed. The | |
1539 | message text is intended to be self explanatory (in the grand Unix | |
1540 | tradition). | |
1541 | ||
1542 | @cindex format of error messages | |
1543 | Error messages have the format | |
1544 | @smallexample | |
1545 | file_name:@b{NNN}:FATAL:Error Message Text | |
1546 | @end smallexample | |
1547 | The file name and line number are derived as for warning | |
1548 | messages. The actual message text may be rather less explanatory | |
1549 | because many of them aren't supposed to happen. | |
1550 | ||
1551 | @node Invoking | |
1552 | @chapter Command-Line Options | |
1553 | ||
1554 | @cindex options, all versions of assembler | |
1555 | This chapter describes command-line options available in @emph{all} | |
96e9638b BW |
1556 | versions of the @sc{gnu} assembler; see @ref{Machine Dependencies}, |
1557 | for options specific | |
252b5132 | 1558 | @ifclear GENERIC |
c1253627 | 1559 | to the @value{TARGET} target. |
252b5132 RH |
1560 | @end ifclear |
1561 | @ifset GENERIC | |
1562 | to particular machine architectures. | |
1563 | @end ifset | |
1564 | ||
0285c67d NC |
1565 | @c man begin DESCRIPTION |
1566 | ||
c1253627 | 1567 | If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler, |
252b5132 RH |
1568 | you can use the @samp{-Wa} option to pass arguments through to the assembler. |
1569 | The assembler arguments must be separated from each other (and the @samp{-Wa}) | |
1570 | by commas. For example: | |
1571 | ||
1572 | @smallexample | |
1573 | gcc -c -g -O -Wa,-alh,-L file.c | |
1574 | @end smallexample | |
1575 | ||
1576 | @noindent | |
1577 | This passes two options to the assembler: @samp{-alh} (emit a listing to | |
5f5e16be | 1578 | standard output with high-level and assembly source) and @samp{-L} (retain |
252b5132 RH |
1579 | local symbols in the symbol table). |
1580 | ||
1581 | Usually you do not need to use this @samp{-Wa} mechanism, since many compiler | |
1582 | command-line options are automatically passed to the assembler by the compiler. | |
1583 | (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see | |
1584 | precisely what options it passes to each compilation pass, including the | |
1585 | assembler.) | |
1586 | ||
0285c67d NC |
1587 | @c man end |
1588 | ||
252b5132 | 1589 | @menu |
83f10cb2 | 1590 | * a:: -a[cdghlns] enable listings |
caa32fe5 | 1591 | * alternate:: --alternate enable alternate macro syntax |
252b5132 RH |
1592 | * D:: -D for compatibility |
1593 | * f:: -f to work faster | |
1594 | * I:: -I for .include search path | |
1595 | @ifclear DIFF-TBL-KLUGE | |
1596 | * K:: -K for compatibility | |
1597 | @end ifclear | |
1598 | @ifset DIFF-TBL-KLUGE | |
1599 | * K:: -K for difference tables | |
1600 | @end ifset | |
1601 | ||
ba83aca1 | 1602 | * L:: -L to retain local symbols |
c3a27914 | 1603 | * listing:: --listing-XXX to configure listing output |
252b5132 RH |
1604 | * M:: -M or --mri to assemble in MRI compatibility mode |
1605 | * MD:: --MD for dependency tracking | |
1606 | * o:: -o to name the object file | |
1607 | * R:: -R to join data and text sections | |
1608 | * statistics:: --statistics to see statistics about assembly | |
1609 | * traditional-format:: --traditional-format for compatible output | |
1610 | * v:: -v to announce version | |
2bdd6cf5 | 1611 | * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings |
252b5132 RH |
1612 | * Z:: -Z to make object file even after errors |
1613 | @end menu | |
1614 | ||
1615 | @node a | |
83f10cb2 | 1616 | @section Enable Listings: @option{-a[cdghlns]} |
252b5132 RH |
1617 | |
1618 | @kindex -a | |
1619 | @kindex -ac | |
1620 | @kindex -ad | |
83f10cb2 | 1621 | @kindex -ag |
252b5132 RH |
1622 | @kindex -ah |
1623 | @kindex -al | |
1624 | @kindex -an | |
1625 | @kindex -as | |
1626 | @cindex listings, enabling | |
1627 | @cindex assembly listings, enabling | |
1628 | ||
1629 | These options enable listing output from the assembler. By itself, | |
1630 | @samp{-a} requests high-level, assembly, and symbols listing. | |
1631 | You can use other letters to select specific options for the list: | |
1632 | @samp{-ah} requests a high-level language listing, | |
1633 | @samp{-al} requests an output-program assembly listing, and | |
1634 | @samp{-as} requests a symbol table listing. | |
1635 | High-level listings require that a compiler debugging option like | |
1636 | @samp{-g} be used, and that assembly listings (@samp{-al}) be requested | |
1637 | also. | |
1638 | ||
83f10cb2 NC |
1639 | Use the @samp{-ag} option to print a first section with general assembly |
1640 | information, like @value{AS} version, switches passed, or time stamp. | |
1641 | ||
252b5132 RH |
1642 | Use the @samp{-ac} option to omit false conditionals from a listing. Any lines |
1643 | which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any | |
1644 | other conditional), or a true @code{.if} followed by an @code{.else}, will be | |
1645 | omitted from the listing. | |
1646 | ||
1647 | Use the @samp{-ad} option to omit debugging directives from the | |
1648 | listing. | |
1649 | ||
1650 | Once you have specified one of these options, you can further control | |
1651 | listing output and its appearance using the directives @code{.list}, | |
1652 | @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and | |
1653 | @code{.sbttl}. | |
1654 | The @samp{-an} option turns off all forms processing. | |
1655 | If you do not request listing output with one of the @samp{-a} options, the | |
1656 | listing-control directives have no effect. | |
1657 | ||
1658 | The letters after @samp{-a} may be combined into one option, | |
1659 | @emph{e.g.}, @samp{-aln}. | |
1660 | ||
96e9638b BW |
1661 | Note if the assembler source is coming from the standard input (e.g., |
1662 | because it | |
c3a27914 NC |
1663 | is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch |
1664 | is being used) then the listing will not contain any comments or preprocessor | |
1665 | directives. This is because the listing code buffers input source lines from | |
1666 | stdin only after they have been preprocessed by the assembler. This reduces | |
1667 | memory usage and makes the code more efficient. | |
1668 | ||
caa32fe5 NC |
1669 | @node alternate |
1670 | @section @option{--alternate} | |
1671 | ||
1672 | @kindex --alternate | |
1673 | Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}. | |
1674 | ||
252b5132 | 1675 | @node D |
a4fb0134 | 1676 | @section @option{-D} |
252b5132 RH |
1677 | |
1678 | @kindex -D | |
1679 | This option has no effect whatsoever, but it is accepted to make it more | |
1680 | likely that scripts written for other assemblers also work with | |
a4fb0134 | 1681 | @command{@value{AS}}. |
252b5132 RH |
1682 | |
1683 | @node f | |
a4fb0134 | 1684 | @section Work Faster: @option{-f} |
252b5132 RH |
1685 | |
1686 | @kindex -f | |
1687 | @cindex trusted compiler | |
a4fb0134 | 1688 | @cindex faster processing (@option{-f}) |
252b5132 RH |
1689 | @samp{-f} should only be used when assembling programs written by a |
1690 | (trusted) compiler. @samp{-f} stops the assembler from doing whitespace | |
1691 | and comment preprocessing on | |
1692 | the input file(s) before assembling them. @xref{Preprocessing, | |
1693 | ,Preprocessing}. | |
1694 | ||
1695 | @quotation | |
1696 | @emph{Warning:} if you use @samp{-f} when the files actually need to be | |
a4fb0134 | 1697 | preprocessed (if they contain comments, for example), @command{@value{AS}} does |
252b5132 RH |
1698 | not work correctly. |
1699 | @end quotation | |
1700 | ||
1701 | @node I | |
c1253627 | 1702 | @section @code{.include} Search Path: @option{-I} @var{path} |
252b5132 RH |
1703 | |
1704 | @kindex -I @var{path} | |
1705 | @cindex paths for @code{.include} | |
1706 | @cindex search path for @code{.include} | |
1707 | @cindex @code{include} directive search path | |
1708 | Use this option to add a @var{path} to the list of directories | |
a4fb0134 SC |
1709 | @command{@value{AS}} searches for files specified in @code{.include} |
1710 | directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as | |
252b5132 | 1711 | many times as necessary to include a variety of paths. The current |
a4fb0134 | 1712 | working directory is always searched first; after that, @command{@value{AS}} |
252b5132 RH |
1713 | searches any @samp{-I} directories in the same order as they were |
1714 | specified (left to right) on the command line. | |
1715 | ||
1716 | @node K | |
a4fb0134 | 1717 | @section Difference Tables: @option{-K} |
252b5132 RH |
1718 | |
1719 | @kindex -K | |
1720 | @ifclear DIFF-TBL-KLUGE | |
1721 | On the @value{TARGET} family, this option is allowed, but has no effect. It is | |
1722 | permitted for compatibility with the @sc{gnu} assembler on other platforms, | |
1723 | where it can be used to warn when the assembler alters the machine code | |
1724 | generated for @samp{.word} directives in difference tables. The @value{TARGET} | |
1725 | family does not have the addressing limitations that sometimes lead to this | |
1726 | alteration on other platforms. | |
1727 | @end ifclear | |
1728 | ||
1729 | @ifset DIFF-TBL-KLUGE | |
1730 | @cindex difference tables, warning | |
1731 | @cindex warning for altered difference tables | |
96e9638b BW |
1732 | @command{@value{AS}} sometimes alters the code emitted for directives of the |
1733 | form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}. | |
252b5132 RH |
1734 | You can use the @samp{-K} option if you want a warning issued when this |
1735 | is done. | |
1736 | @end ifset | |
1737 | ||
1738 | @node L | |
ba83aca1 | 1739 | @section Include Local Symbols: @option{-L} |
252b5132 RH |
1740 | |
1741 | @kindex -L | |
ba83aca1 BW |
1742 | @cindex local symbols, retaining in output |
1743 | Symbols beginning with system-specific local label prefixes, typically | |
1744 | @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are | |
1745 | called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see | |
1746 | such symbols when debugging, because they are intended for the use of | |
1747 | programs (like compilers) that compose assembler programs, not for your | |
1748 | notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard | |
1749 | such symbols, so you do not normally debug with them. | |
1750 | ||
1751 | This option tells @command{@value{AS}} to retain those local symbols | |
252b5132 | 1752 | in the object file. Usually if you do this you also tell the linker |
ba83aca1 | 1753 | @code{@value{LD}} to preserve those symbols. |
252b5132 | 1754 | |
c3a27914 | 1755 | @node listing |
a4fb0134 | 1756 | @section Configuring listing output: @option{--listing} |
c3a27914 NC |
1757 | |
1758 | The listing feature of the assembler can be enabled via the command line switch | |
1759 | @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a | |
1760 | hex dump of the corresponding locations in the output object file, and displays | |
96e9638b BW |
1761 | them as a listing file. The format of this listing can be controlled by |
1762 | directives inside the assembler source (i.e., @code{.list} (@pxref{List}), | |
1763 | @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}), | |
1764 | @code{.psize} (@pxref{Psize}), and | |
1765 | @code{.eject} (@pxref{Eject}) and also by the following switches: | |
c3a27914 | 1766 | |
a4fb0134 | 1767 | @table @gcctabopt |
c3a27914 NC |
1768 | @item --listing-lhs-width=@samp{number} |
1769 | @kindex --listing-lhs-width | |
1770 | @cindex Width of first line disassembly output | |
1771 | Sets the maximum width, in words, of the first line of the hex byte dump. This | |
1772 | dump appears on the left hand side of the listing output. | |
1773 | ||
1774 | @item --listing-lhs-width2=@samp{number} | |
1775 | @kindex --listing-lhs-width2 | |
1776 | @cindex Width of continuation lines of disassembly output | |
1777 | Sets the maximum width, in words, of any further lines of the hex byte dump for | |
8dfa0188 | 1778 | a given input source line. If this value is not specified, it defaults to being |
c3a27914 NC |
1779 | the same as the value specified for @samp{--listing-lhs-width}. If neither |
1780 | switch is used the default is to one. | |
1781 | ||
1782 | @item --listing-rhs-width=@samp{number} | |
1783 | @kindex --listing-rhs-width | |
1784 | @cindex Width of source line output | |
1785 | Sets the maximum width, in characters, of the source line that is displayed | |
1786 | alongside the hex dump. The default value for this parameter is 100. The | |
1787 | source line is displayed on the right hand side of the listing output. | |
1788 | ||
1789 | @item --listing-cont-lines=@samp{number} | |
1790 | @kindex --listing-cont-lines | |
1791 | @cindex Maximum number of continuation lines | |
1792 | Sets the maximum number of continuation lines of hex dump that will be | |
1793 | displayed for a given single line of source input. The default value is 4. | |
1794 | @end table | |
1795 | ||
252b5132 | 1796 | @node M |
a4fb0134 | 1797 | @section Assemble in MRI Compatibility Mode: @option{-M} |
252b5132 RH |
1798 | |
1799 | @kindex -M | |
1800 | @cindex MRI compatibility mode | |
a4fb0134 SC |
1801 | The @option{-M} or @option{--mri} option selects MRI compatibility mode. This |
1802 | changes the syntax and pseudo-op handling of @command{@value{AS}} to make it | |
252b5132 RH |
1803 | compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the |
1804 | configured target) assembler from Microtec Research. The exact nature of the | |
1805 | MRI syntax will not be documented here; see the MRI manuals for more | |
1806 | information. Note in particular that the handling of macros and macro | |
1807 | arguments is somewhat different. The purpose of this option is to permit | |
a4fb0134 | 1808 | assembling existing MRI assembler code using @command{@value{AS}}. |
252b5132 RH |
1809 | |
1810 | The MRI compatibility is not complete. Certain operations of the MRI assembler | |
1811 | depend upon its object file format, and can not be supported using other object | |
1812 | file formats. Supporting these would require enhancing each object file format | |
1813 | individually. These are: | |
1814 | ||
1815 | @itemize @bullet | |
1816 | @item global symbols in common section | |
1817 | ||
1818 | The m68k MRI assembler supports common sections which are merged by the linker. | |
a4fb0134 | 1819 | Other object file formats do not support this. @command{@value{AS}} handles |
252b5132 RH |
1820 | common sections by treating them as a single common symbol. It permits local |
1821 | symbols to be defined within a common section, but it can not support global | |
1822 | symbols, since it has no way to describe them. | |
1823 | ||
1824 | @item complex relocations | |
1825 | ||
1826 | The MRI assemblers support relocations against a negated section address, and | |
1827 | relocations which combine the start addresses of two or more sections. These | |
1828 | are not support by other object file formats. | |
1829 | ||
1830 | @item @code{END} pseudo-op specifying start address | |
1831 | ||
1832 | The MRI @code{END} pseudo-op permits the specification of a start address. | |
1833 | This is not supported by other object file formats. The start address may | |
a4fb0134 | 1834 | instead be specified using the @option{-e} option to the linker, or in a linker |
252b5132 RH |
1835 | script. |
1836 | ||
1837 | @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops | |
1838 | ||
1839 | The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module | |
1840 | name to the output file. This is not supported by other object file formats. | |
1841 | ||
1842 | @item @code{ORG} pseudo-op | |
1843 | ||
1844 | The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given | |
a4fb0134 | 1845 | address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op, |
252b5132 RH |
1846 | which changes the location within the current section. Absolute sections are |
1847 | not supported by other object file formats. The address of a section may be | |
1848 | assigned within a linker script. | |
1849 | @end itemize | |
1850 | ||
1851 | There are some other features of the MRI assembler which are not supported by | |
a4fb0134 | 1852 | @command{@value{AS}}, typically either because they are difficult or because they |
252b5132 RH |
1853 | seem of little consequence. Some of these may be supported in future releases. |
1854 | ||
1855 | @itemize @bullet | |
1856 | ||
1857 | @item EBCDIC strings | |
1858 | ||
1859 | EBCDIC strings are not supported. | |
1860 | ||
1861 | @item packed binary coded decimal | |
1862 | ||
1863 | Packed binary coded decimal is not supported. This means that the @code{DC.P} | |
1864 | and @code{DCB.P} pseudo-ops are not supported. | |
1865 | ||
1866 | @item @code{FEQU} pseudo-op | |
1867 | ||
1868 | The m68k @code{FEQU} pseudo-op is not supported. | |
1869 | ||
1870 | @item @code{NOOBJ} pseudo-op | |
1871 | ||
1872 | The m68k @code{NOOBJ} pseudo-op is not supported. | |
1873 | ||
1874 | @item @code{OPT} branch control options | |
1875 | ||
1876 | The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB}, | |
a4fb0134 | 1877 | @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically |
252b5132 RH |
1878 | relaxes all branches, whether forward or backward, to an appropriate size, so |
1879 | these options serve no purpose. | |
1880 | ||
1881 | @item @code{OPT} list control options | |
1882 | ||
1883 | The following m68k @code{OPT} list control options are ignored: @code{C}, | |
1884 | @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M}, | |
1885 | @code{MEX}, @code{MC}, @code{MD}, @code{X}. | |
1886 | ||
1887 | @item other @code{OPT} options | |
1888 | ||
1889 | The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O}, | |
1890 | @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}. | |
1891 | ||
1892 | @item @code{OPT} @code{D} option is default | |
1893 | ||
1894 | The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler. | |
1895 | @code{OPT NOD} may be used to turn it off. | |
1896 | ||
1897 | @item @code{XREF} pseudo-op. | |
1898 | ||
1899 | The m68k @code{XREF} pseudo-op is ignored. | |
1900 | ||
1901 | @item @code{.debug} pseudo-op | |
1902 | ||
1903 | The i960 @code{.debug} pseudo-op is not supported. | |
1904 | ||
1905 | @item @code{.extended} pseudo-op | |
1906 | ||
1907 | The i960 @code{.extended} pseudo-op is not supported. | |
1908 | ||
1909 | @item @code{.list} pseudo-op. | |
1910 | ||
1911 | The various options of the i960 @code{.list} pseudo-op are not supported. | |
1912 | ||
1913 | @item @code{.optimize} pseudo-op | |
1914 | ||
1915 | The i960 @code{.optimize} pseudo-op is not supported. | |
1916 | ||
1917 | @item @code{.output} pseudo-op | |
1918 | ||
1919 | The i960 @code{.output} pseudo-op is not supported. | |
1920 | ||
1921 | @item @code{.setreal} pseudo-op | |
1922 | ||
1923 | The i960 @code{.setreal} pseudo-op is not supported. | |
1924 | ||
1925 | @end itemize | |
1926 | ||
1927 | @node MD | |
c1253627 | 1928 | @section Dependency Tracking: @option{--MD} |
252b5132 RH |
1929 | |
1930 | @kindex --MD | |
1931 | @cindex dependency tracking | |
1932 | @cindex make rules | |
1933 | ||
a4fb0134 | 1934 | @command{@value{AS}} can generate a dependency file for the file it creates. This |
252b5132 RH |
1935 | file consists of a single rule suitable for @code{make} describing the |
1936 | dependencies of the main source file. | |
1937 | ||
1938 | The rule is written to the file named in its argument. | |
1939 | ||
1940 | This feature is used in the automatic updating of makefiles. | |
1941 | ||
1942 | @node o | |
a4fb0134 | 1943 | @section Name the Object File: @option{-o} |
252b5132 RH |
1944 | |
1945 | @kindex -o | |
1946 | @cindex naming object file | |
1947 | @cindex object file name | |
a4fb0134 | 1948 | There is always one object file output when you run @command{@value{AS}}. By |
252b5132 RH |
1949 | default it has the name |
1950 | @ifset GENERIC | |
1951 | @ifset I960 | |
1952 | @file{a.out} (or @file{b.out}, for Intel 960 targets only). | |
1953 | @end ifset | |
1954 | @ifclear I960 | |
1955 | @file{a.out}. | |
1956 | @end ifclear | |
1957 | @end ifset | |
1958 | @ifclear GENERIC | |
1959 | @ifset I960 | |
1960 | @file{b.out}. | |
1961 | @end ifset | |
1962 | @ifclear I960 | |
1963 | @file{a.out}. | |
1964 | @end ifclear | |
1965 | @end ifclear | |
1966 | You use this option (which takes exactly one filename) to give the | |
1967 | object file a different name. | |
1968 | ||
a4fb0134 | 1969 | Whatever the object file is called, @command{@value{AS}} overwrites any |
252b5132 RH |
1970 | existing file of the same name. |
1971 | ||
1972 | @node R | |
a4fb0134 | 1973 | @section Join Data and Text Sections: @option{-R} |
252b5132 RH |
1974 | |
1975 | @kindex -R | |
1976 | @cindex data and text sections, joining | |
1977 | @cindex text and data sections, joining | |
1978 | @cindex joining text and data sections | |
1979 | @cindex merging text and data sections | |
a4fb0134 | 1980 | @option{-R} tells @command{@value{AS}} to write the object file as if all |
252b5132 RH |
1981 | data-section data lives in the text section. This is only done at |
1982 | the very last moment: your binary data are the same, but data | |
1983 | section parts are relocated differently. The data section part of | |
1984 | your object file is zero bytes long because all its bytes are | |
1985 | appended to the text section. (@xref{Sections,,Sections and Relocation}.) | |
1986 | ||
a4fb0134 | 1987 | When you specify @option{-R} it would be possible to generate shorter |
252b5132 RH |
1988 | address displacements (because we do not have to cross between text and |
1989 | data section). We refrain from doing this simply for compatibility with | |
a4fb0134 | 1990 | older versions of @command{@value{AS}}. In future, @option{-R} may work this way. |
252b5132 | 1991 | |
c1253627 NC |
1992 | @ifset COFF-ELF |
1993 | When @command{@value{AS}} is configured for COFF or ELF output, | |
252b5132 RH |
1994 | this option is only useful if you use sections named @samp{.text} and |
1995 | @samp{.data}. | |
1996 | @end ifset | |
1997 | ||
1998 | @ifset HPPA | |
a4fb0134 SC |
1999 | @option{-R} is not supported for any of the HPPA targets. Using |
2000 | @option{-R} generates a warning from @command{@value{AS}}. | |
252b5132 RH |
2001 | @end ifset |
2002 | ||
2003 | @node statistics | |
a4fb0134 | 2004 | @section Display Assembly Statistics: @option{--statistics} |
252b5132 RH |
2005 | |
2006 | @kindex --statistics | |
2007 | @cindex statistics, about assembly | |
2008 | @cindex time, total for assembly | |
2009 | @cindex space used, maximum for assembly | |
2010 | Use @samp{--statistics} to display two statistics about the resources used by | |
a4fb0134 | 2011 | @command{@value{AS}}: the maximum amount of space allocated during the assembly |
252b5132 RH |
2012 | (in bytes), and the total execution time taken for the assembly (in @sc{cpu} |
2013 | seconds). | |
2014 | ||
2015 | @node traditional-format | |
c1253627 | 2016 | @section Compatible Output: @option{--traditional-format} |
252b5132 RH |
2017 | |
2018 | @kindex --traditional-format | |
a4fb0134 | 2019 | For some targets, the output of @command{@value{AS}} is different in some ways |
252b5132 | 2020 | from the output of some existing assembler. This switch requests |
a4fb0134 | 2021 | @command{@value{AS}} to use the traditional format instead. |
252b5132 RH |
2022 | |
2023 | For example, it disables the exception frame optimizations which | |
a4fb0134 | 2024 | @command{@value{AS}} normally does by default on @code{@value{GCC}} output. |
252b5132 RH |
2025 | |
2026 | @node v | |
a4fb0134 | 2027 | @section Announce Version: @option{-v} |
252b5132 RH |
2028 | |
2029 | @kindex -v | |
2030 | @kindex -version | |
2031 | @cindex assembler version | |
2032 | @cindex version of assembler | |
2033 | You can find out what version of as is running by including the | |
2034 | option @samp{-v} (which you can also spell as @samp{-version}) on the | |
2035 | command line. | |
2036 | ||
2037 | @node W | |
a4fb0134 | 2038 | @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings} |
252b5132 | 2039 | |
a4fb0134 | 2040 | @command{@value{AS}} should never give a warning or error message when |
252b5132 | 2041 | assembling compiler output. But programs written by people often |
a4fb0134 | 2042 | cause @command{@value{AS}} to give a warning that a particular assumption was |
252b5132 | 2043 | made. All such warnings are directed to the standard error file. |
2bdd6cf5 | 2044 | |
c1253627 NC |
2045 | @kindex -W |
2046 | @kindex --no-warn | |
2bdd6cf5 GK |
2047 | @cindex suppressing warnings |
2048 | @cindex warnings, suppressing | |
a4fb0134 | 2049 | If you use the @option{-W} and @option{--no-warn} options, no warnings are issued. |
2bdd6cf5 | 2050 | This only affects the warning messages: it does not change any particular of |
a4fb0134 | 2051 | how @command{@value{AS}} assembles your file. Errors, which stop the assembly, |
2bdd6cf5 GK |
2052 | are still reported. |
2053 | ||
c1253627 | 2054 | @kindex --fatal-warnings |
2bdd6cf5 GK |
2055 | @cindex errors, caused by warnings |
2056 | @cindex warnings, causing error | |
a4fb0134 | 2057 | If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers |
2bdd6cf5 GK |
2058 | files that generate warnings to be in error. |
2059 | ||
c1253627 | 2060 | @kindex --warn |
2bdd6cf5 | 2061 | @cindex warnings, switching on |
a4fb0134 | 2062 | You can switch these options off again by specifying @option{--warn}, which |
2bdd6cf5 | 2063 | causes warnings to be output as usual. |
252b5132 RH |
2064 | |
2065 | @node Z | |
a4fb0134 | 2066 | @section Generate Object File in Spite of Errors: @option{-Z} |
252b5132 RH |
2067 | @cindex object file, after errors |
2068 | @cindex errors, continuing after | |
a4fb0134 | 2069 | After an error message, @command{@value{AS}} normally produces no output. If for |
252b5132 | 2070 | some reason you are interested in object file output even after |
a4fb0134 SC |
2071 | @command{@value{AS}} gives an error message on your program, use the @samp{-Z} |
2072 | option. If there are any errors, @command{@value{AS}} continues anyways, and | |
252b5132 RH |
2073 | writes an object file after a final warning message of the form @samp{@var{n} |
2074 | errors, @var{m} warnings, generating bad object file.} | |
2075 | ||
2076 | @node Syntax | |
2077 | @chapter Syntax | |
2078 | ||
2079 | @cindex machine-independent syntax | |
2080 | @cindex syntax, machine-independent | |
2081 | This chapter describes the machine-independent syntax allowed in a | |
a4fb0134 | 2082 | source file. @command{@value{AS}} syntax is similar to what many other |
252b5132 RH |
2083 | assemblers use; it is inspired by the BSD 4.2 |
2084 | @ifclear VAX | |
2085 | assembler. | |
2086 | @end ifclear | |
2087 | @ifset VAX | |
a4fb0134 | 2088 | assembler, except that @command{@value{AS}} does not assemble Vax bit-fields. |
252b5132 RH |
2089 | @end ifset |
2090 | ||
2091 | @menu | |
2092 | * Preprocessing:: Preprocessing | |
2093 | * Whitespace:: Whitespace | |
2094 | * Comments:: Comments | |
2095 | * Symbol Intro:: Symbols | |
2096 | * Statements:: Statements | |
2097 | * Constants:: Constants | |
2098 | @end menu | |
2099 | ||
2100 | @node Preprocessing | |
2101 | @section Preprocessing | |
2102 | ||
2103 | @cindex preprocessing | |
a4fb0134 | 2104 | The @command{@value{AS}} internal preprocessor: |
252b5132 RH |
2105 | @itemize @bullet |
2106 | @cindex whitespace, removed by preprocessor | |
2107 | @item | |
2108 | adjusts and removes extra whitespace. It leaves one space or tab before | |
2109 | the keywords on a line, and turns any other whitespace on the line into | |
2110 | a single space. | |
2111 | ||
2112 | @cindex comments, removed by preprocessor | |
2113 | @item | |
2114 | removes all comments, replacing them with a single space, or an | |
2115 | appropriate number of newlines. | |
2116 | ||
2117 | @cindex constants, converted by preprocessor | |
2118 | @item | |
2119 | converts character constants into the appropriate numeric values. | |
2120 | @end itemize | |
2121 | ||
2122 | It does not do macro processing, include file handling, or | |
2123 | anything else you may get from your C compiler's preprocessor. You can | |
2124 | do include file processing with the @code{.include} directive | |
2125 | (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver | |
c1253627 | 2126 | to get other ``CPP'' style preprocessing by giving the input file a |
96e9638b | 2127 | @samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of |
252b5132 RH |
2128 | Output, gcc.info, Using GNU CC}. |
2129 | ||
2130 | Excess whitespace, comments, and character constants | |
2131 | cannot be used in the portions of the input text that are not | |
2132 | preprocessed. | |
2133 | ||
2134 | @cindex turning preprocessing on and off | |
2135 | @cindex preprocessing, turning on and off | |
2136 | @kindex #NO_APP | |
2137 | @kindex #APP | |
2138 | If the first line of an input file is @code{#NO_APP} or if you use the | |
2139 | @samp{-f} option, whitespace and comments are not removed from the input file. | |
2140 | Within an input file, you can ask for whitespace and comment removal in | |
2141 | specific portions of the by putting a line that says @code{#APP} before the | |
2142 | text that may contain whitespace or comments, and putting a line that says | |
2143 | @code{#NO_APP} after this text. This feature is mainly intend to support | |
2144 | @code{asm} statements in compilers whose output is otherwise free of comments | |
2145 | and whitespace. | |
2146 | ||
2147 | @node Whitespace | |
2148 | @section Whitespace | |
2149 | ||
2150 | @cindex whitespace | |
2151 | @dfn{Whitespace} is one or more blanks or tabs, in any order. | |
2152 | Whitespace is used to separate symbols, and to make programs neater for | |
2153 | people to read. Unless within character constants | |
2154 | (@pxref{Characters,,Character Constants}), any whitespace means the same | |
2155 | as exactly one space. | |
2156 | ||
2157 | @node Comments | |
2158 | @section Comments | |
2159 | ||
2160 | @cindex comments | |
a4fb0134 | 2161 | There are two ways of rendering comments to @command{@value{AS}}. In both |
252b5132 RH |
2162 | cases the comment is equivalent to one space. |
2163 | ||
2164 | Anything from @samp{/*} through the next @samp{*/} is a comment. | |
2165 | This means you may not nest these comments. | |
2166 | ||
2167 | @smallexample | |
2168 | /* | |
2169 | The only way to include a newline ('\n') in a comment | |
2170 | is to use this sort of comment. | |
2171 | */ | |
2172 | ||
2173 | /* This sort of comment does not nest. */ | |
2174 | @end smallexample | |
2175 | ||
2176 | @cindex line comment character | |
2177 | Anything from the @dfn{line comment} character to the next newline | |
2178 | is considered a comment and is ignored. The line comment character is | |
252b5132 RH |
2179 | @ifset ARC |
2180 | @samp{;} on the ARC; | |
2181 | @end ifset | |
550262c4 NC |
2182 | @ifset ARM |
2183 | @samp{@@} on the ARM; | |
2184 | @end ifset | |
252b5132 RH |
2185 | @ifset H8/300 |
2186 | @samp{;} for the H8/300 family; | |
2187 | @end ifset | |
252b5132 RH |
2188 | @ifset HPPA |
2189 | @samp{;} for the HPPA; | |
2190 | @end ifset | |
55b62671 AJ |
2191 | @ifset I80386 |
2192 | @samp{#} on the i386 and x86-64; | |
2193 | @end ifset | |
252b5132 RH |
2194 | @ifset I960 |
2195 | @samp{#} on the i960; | |
2196 | @end ifset | |
e135f41b NC |
2197 | @ifset PDP11 |
2198 | @samp{;} for the PDP-11; | |
2199 | @end ifset | |
041dd5a9 ILT |
2200 | @ifset PJ |
2201 | @samp{;} for picoJava; | |
2202 | @end ifset | |
418c1742 | 2203 | @ifset PPC |
3fb9d77f | 2204 | @samp{#} for Motorola PowerPC; |
418c1742 | 2205 | @end ifset |
252b5132 | 2206 | @ifset SH |
ef230218 | 2207 | @samp{!} for the Renesas / SuperH SH; |
252b5132 RH |
2208 | @end ifset |
2209 | @ifset SPARC | |
2210 | @samp{!} on the SPARC; | |
2211 | @end ifset | |
a40cbfa3 NC |
2212 | @ifset IP2K |
2213 | @samp{#} on the ip2k; | |
2214 | @end ifset | |
49f58d10 JB |
2215 | @ifset M32C |
2216 | @samp{#} on the m32c; | |
2217 | @end ifset | |
252b5132 RH |
2218 | @ifset M32R |
2219 | @samp{#} on the m32r; | |
2220 | @end ifset | |
2221 | @ifset M680X0 | |
2222 | @samp{|} on the 680x0; | |
2223 | @end ifset | |
60bcf0fa NC |
2224 | @ifset M68HC11 |
2225 | @samp{#} on the 68HC11 and 68HC12; | |
2226 | @end ifset | |
252b5132 RH |
2227 | @ifset VAX |
2228 | @samp{#} on the Vax; | |
2229 | @end ifset | |
3c9b82ba NC |
2230 | @ifset Z80 |
2231 | @samp{;} for the Z80; | |
2232 | @end ifset | |
252b5132 RH |
2233 | @ifset Z8000 |
2234 | @samp{!} for the Z8000; | |
2235 | @end ifset | |
2236 | @ifset V850 | |
2237 | @samp{#} on the V850; | |
2238 | @end ifset | |
e0001a05 NC |
2239 | @ifset XTENSA |
2240 | @samp{#} for Xtensa systems; | |
2241 | @end ifset | |
252b5132 | 2242 | see @ref{Machine Dependencies}. @refill |
81b0b3f1 | 2243 | @c FIXME What about i860? |
252b5132 RH |
2244 | |
2245 | @ifset GENERIC | |
2246 | On some machines there are two different line comment characters. One | |
2247 | character only begins a comment if it is the first non-whitespace character on | |
2248 | a line, while the other always begins a comment. | |
2249 | @end ifset | |
2250 | ||
2251 | @ifset V850 | |
2252 | The V850 assembler also supports a double dash as starting a comment that | |
2253 | extends to the end of the line. | |
2254 | ||
2255 | @samp{--}; | |
2256 | @end ifset | |
2257 | ||
2258 | @kindex # | |
2259 | @cindex lines starting with @code{#} | |
2260 | @cindex logical line numbers | |
2261 | To be compatible with past assemblers, lines that begin with @samp{#} have a | |
2262 | special interpretation. Following the @samp{#} should be an absolute | |
2263 | expression (@pxref{Expressions}): the logical line number of the @emph{next} | |
96e9638b | 2264 | line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a |
252b5132 RH |
2265 | new logical file name. The rest of the line, if any, should be whitespace. |
2266 | ||
2267 | If the first non-whitespace characters on the line are not numeric, | |
2268 | the line is ignored. (Just like a comment.) | |
2269 | ||
2270 | @smallexample | |
2271 | # This is an ordinary comment. | |
2272 | # 42-6 "new_file_name" # New logical file name | |
2273 | # This is logical line # 36. | |
2274 | @end smallexample | |
2275 | This feature is deprecated, and may disappear from future versions | |
a4fb0134 | 2276 | of @command{@value{AS}}. |
252b5132 RH |
2277 | |
2278 | @node Symbol Intro | |
2279 | @section Symbols | |
2280 | ||
2281 | @cindex characters used in symbols | |
2282 | @ifclear SPECIAL-SYMS | |
2283 | A @dfn{symbol} is one or more characters chosen from the set of all | |
2284 | letters (both upper and lower case), digits and the three characters | |
2285 | @samp{_.$}. | |
2286 | @end ifclear | |
2287 | @ifset SPECIAL-SYMS | |
2288 | @ifclear GENERIC | |
2289 | @ifset H8 | |
2290 | A @dfn{symbol} is one or more characters chosen from the set of all | |
2291 | letters (both upper and lower case), digits and the three characters | |
2292 | @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in | |
2293 | symbol names.) | |
2294 | @end ifset | |
2295 | @end ifclear | |
2296 | @end ifset | |
2297 | @ifset GENERIC | |
2298 | On most machines, you can also use @code{$} in symbol names; exceptions | |
2299 | are noted in @ref{Machine Dependencies}. | |
2300 | @end ifset | |
2301 | No symbol may begin with a digit. Case is significant. | |
2302 | There is no length limit: all characters are significant. Symbols are | |
2303 | delimited by characters not in that set, or by the beginning of a file | |
2304 | (since the source program must end with a newline, the end of a file is | |
2305 | not a possible symbol delimiter). @xref{Symbols}. | |
2306 | @cindex length of symbols | |
2307 | ||
2308 | @node Statements | |
2309 | @section Statements | |
2310 | ||
2311 | @cindex statements, structure of | |
2312 | @cindex line separator character | |
2313 | @cindex statement separator character | |
2314 | @ifclear GENERIC | |
2315 | @ifclear abnormal-separator | |
2316 | A @dfn{statement} ends at a newline character (@samp{\n}) or at a | |
2317 | semicolon (@samp{;}). The newline or semicolon is considered part of | |
2318 | the preceding statement. Newlines and semicolons within character | |
2319 | constants are an exception: they do not end statements. | |
2320 | @end ifclear | |
2321 | @ifset abnormal-separator | |
252b5132 RH |
2322 | @ifset HPPA |
2323 | A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation | |
2324 | point (@samp{!}). The newline or exclamation point is considered part of the | |
2325 | preceding statement. Newlines and exclamation points within character | |
2326 | constants are an exception: they do not end statements. | |
2327 | @end ifset | |
2328 | @ifset H8 | |
2329 | A @dfn{statement} ends at a newline character (@samp{\n}); or (for the | |
7be1c489 | 2330 | H8/300) a dollar sign (@samp{$}); or (for the Renesas-SH) a semicolon |
252b5132 RH |
2331 | (@samp{;}). The newline or separator character is considered part of |
2332 | the preceding statement. Newlines and separators within character | |
2333 | constants are an exception: they do not end statements. | |
2334 | @end ifset | |
2335 | @end ifset | |
2336 | @end ifclear | |
2337 | @ifset GENERIC | |
2338 | A @dfn{statement} ends at a newline character (@samp{\n}) or line | |
96e9638b BW |
2339 | separator character. (The line separator is usually @samp{;}, unless this |
2340 | conflicts with the comment character; see @ref{Machine Dependencies}.) The | |
252b5132 RH |
2341 | newline or separator character is considered part of the preceding |
2342 | statement. Newlines and separators within character constants are an | |
2343 | exception: they do not end statements. | |
2344 | @end ifset | |
2345 | ||
2346 | @cindex newline, required at file end | |
2347 | @cindex EOF, newline must precede | |
2348 | It is an error to end any statement with end-of-file: the last | |
2349 | character of any input file should be a newline.@refill | |
2350 | ||
2351 | An empty statement is allowed, and may include whitespace. It is ignored. | |
2352 | ||
2353 | @cindex instructions and directives | |
2354 | @cindex directives and instructions | |
2355 | @c "key symbol" is not used elsewhere in the document; seems pedantic to | |
2356 | @c @defn{} it in that case, as was done previously... doc@cygnus.com, | |
2357 | @c 13feb91. | |
2358 | A statement begins with zero or more labels, optionally followed by a | |
2359 | key symbol which determines what kind of statement it is. The key | |
2360 | symbol determines the syntax of the rest of the statement. If the | |
2361 | symbol begins with a dot @samp{.} then the statement is an assembler | |
2362 | directive: typically valid for any computer. If the symbol begins with | |
2363 | a letter the statement is an assembly language @dfn{instruction}: it | |
2364 | assembles into a machine language instruction. | |
2365 | @ifset GENERIC | |
a4fb0134 | 2366 | Different versions of @command{@value{AS}} for different computers |
252b5132 RH |
2367 | recognize different instructions. In fact, the same symbol may |
2368 | represent a different instruction in a different computer's assembly | |
2369 | language.@refill | |
2370 | @end ifset | |
2371 | ||
2372 | @cindex @code{:} (label) | |
2373 | @cindex label (@code{:}) | |
2374 | A label is a symbol immediately followed by a colon (@code{:}). | |
2375 | Whitespace before a label or after a colon is permitted, but you may not | |
2376 | have whitespace between a label's symbol and its colon. @xref{Labels}. | |
2377 | ||
2378 | @ifset HPPA | |
2379 | For HPPA targets, labels need not be immediately followed by a colon, but | |
2380 | the definition of a label must begin in column zero. This also implies that | |
2381 | only one label may be defined on each line. | |
2382 | @end ifset | |
2383 | ||
2384 | @smallexample | |
2385 | label: .directive followed by something | |
2386 | another_label: # This is an empty statement. | |
2387 | instruction operand_1, operand_2, @dots{} | |
2388 | @end smallexample | |
2389 | ||
2390 | @node Constants | |
2391 | @section Constants | |
2392 | ||
2393 | @cindex constants | |
2394 | A constant is a number, written so that its value is known by | |
2395 | inspection, without knowing any context. Like this: | |
2396 | @smallexample | |
2397 | @group | |
2398 | .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value. | |
2399 | .ascii "Ring the bell\7" # A string constant. | |
2400 | .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum. | |
2401 | .float 0f-314159265358979323846264338327\ | |
2402 | 95028841971.693993751E-40 # - pi, a flonum. | |
2403 | @end group | |
2404 | @end smallexample | |
2405 | ||
2406 | @menu | |
2407 | * Characters:: Character Constants | |
2408 | * Numbers:: Number Constants | |
2409 | @end menu | |
2410 | ||
2411 | @node Characters | |
2412 | @subsection Character Constants | |
2413 | ||
2414 | @cindex character constants | |
2415 | @cindex constants, character | |
2416 | There are two kinds of character constants. A @dfn{character} stands | |
2417 | for one character in one byte and its value may be used in | |
2418 | numeric expressions. String constants (properly called string | |
2419 | @emph{literals}) are potentially many bytes and their values may not be | |
2420 | used in arithmetic expressions. | |
2421 | ||
2422 | @menu | |
2423 | * Strings:: Strings | |
2424 | * Chars:: Characters | |
2425 | @end menu | |
2426 | ||
2427 | @node Strings | |
2428 | @subsubsection Strings | |
2429 | ||
2430 | @cindex string constants | |
2431 | @cindex constants, string | |
2432 | A @dfn{string} is written between double-quotes. It may contain | |
2433 | double-quotes or null characters. The way to get special characters | |
2434 | into a string is to @dfn{escape} these characters: precede them with | |
2435 | a backslash @samp{\} character. For example @samp{\\} represents | |
2436 | one backslash: the first @code{\} is an escape which tells | |
a4fb0134 SC |
2437 | @command{@value{AS}} to interpret the second character literally as a backslash |
2438 | (which prevents @command{@value{AS}} from recognizing the second @code{\} as an | |
252b5132 RH |
2439 | escape character). The complete list of escapes follows. |
2440 | ||
2441 | @cindex escape codes, character | |
2442 | @cindex character escape codes | |
2443 | @table @kbd | |
2444 | @c @item \a | |
2445 | @c Mnemonic for ACKnowledge; for ASCII this is octal code 007. | |
2446 | @c | |
2447 | @cindex @code{\b} (backspace character) | |
2448 | @cindex backspace (@code{\b}) | |
2449 | @item \b | |
2450 | Mnemonic for backspace; for ASCII this is octal code 010. | |
2451 | ||
2452 | @c @item \e | |
2453 | @c Mnemonic for EOText; for ASCII this is octal code 004. | |
2454 | @c | |
2455 | @cindex @code{\f} (formfeed character) | |
2456 | @cindex formfeed (@code{\f}) | |
2457 | @item \f | |
2458 | Mnemonic for FormFeed; for ASCII this is octal code 014. | |
2459 | ||
2460 | @cindex @code{\n} (newline character) | |
2461 | @cindex newline (@code{\n}) | |
2462 | @item \n | |
2463 | Mnemonic for newline; for ASCII this is octal code 012. | |
2464 | ||
2465 | @c @item \p | |
2466 | @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}. | |
2467 | @c | |
2468 | @cindex @code{\r} (carriage return character) | |
2469 | @cindex carriage return (@code{\r}) | |
2470 | @item \r | |
2471 | Mnemonic for carriage-Return; for ASCII this is octal code 015. | |
2472 | ||
2473 | @c @item \s | |
2474 | @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with | |
2475 | @c other assemblers. | |
2476 | @c | |
2477 | @cindex @code{\t} (tab) | |
2478 | @cindex tab (@code{\t}) | |
2479 | @item \t | |
2480 | Mnemonic for horizontal Tab; for ASCII this is octal code 011. | |
2481 | ||
2482 | @c @item \v | |
2483 | @c Mnemonic for Vertical tab; for ASCII this is octal code 013. | |
2484 | @c @item \x @var{digit} @var{digit} @var{digit} | |
2485 | @c A hexadecimal character code. The numeric code is 3 hexadecimal digits. | |
2486 | @c | |
2487 | @cindex @code{\@var{ddd}} (octal character code) | |
2488 | @cindex octal character code (@code{\@var{ddd}}) | |
2489 | @item \ @var{digit} @var{digit} @var{digit} | |
2490 | An octal character code. The numeric code is 3 octal digits. | |
2491 | For compatibility with other Unix systems, 8 and 9 are accepted as digits: | |
2492 | for example, @code{\008} has the value 010, and @code{\009} the value 011. | |
2493 | ||
2494 | @cindex @code{\@var{xd...}} (hex character code) | |
2495 | @cindex hex character code (@code{\@var{xd...}}) | |
2496 | @item \@code{x} @var{hex-digits...} | |
2497 | A hex character code. All trailing hex digits are combined. Either upper or | |
2498 | lower case @code{x} works. | |
2499 | ||
2500 | @cindex @code{\\} (@samp{\} character) | |
2501 | @cindex backslash (@code{\\}) | |
2502 | @item \\ | |
2503 | Represents one @samp{\} character. | |
2504 | ||
2505 | @c @item \' | |
2506 | @c Represents one @samp{'} (accent acute) character. | |
2507 | @c This is needed in single character literals | |
2508 | @c (@xref{Characters,,Character Constants}.) to represent | |
2509 | @c a @samp{'}. | |
2510 | @c | |
2511 | @cindex @code{\"} (doublequote character) | |
2512 | @cindex doublequote (@code{\"}) | |
2513 | @item \" | |
2514 | Represents one @samp{"} character. Needed in strings to represent | |
2515 | this character, because an unescaped @samp{"} would end the string. | |
2516 | ||
2517 | @item \ @var{anything-else} | |
2518 | Any other character when escaped by @kbd{\} gives a warning, but | |
2519 | assembles as if the @samp{\} was not present. The idea is that if | |
2520 | you used an escape sequence you clearly didn't want the literal | |
a4fb0134 SC |
2521 | interpretation of the following character. However @command{@value{AS}} has no |
2522 | other interpretation, so @command{@value{AS}} knows it is giving you the wrong | |
252b5132 RH |
2523 | code and warns you of the fact. |
2524 | @end table | |
2525 | ||
2526 | Which characters are escapable, and what those escapes represent, | |
2527 | varies widely among assemblers. The current set is what we think | |
2528 | the BSD 4.2 assembler recognizes, and is a subset of what most C | |
2529 | compilers recognize. If you are in doubt, do not use an escape | |
2530 | sequence. | |
2531 | ||
2532 | @node Chars | |
2533 | @subsubsection Characters | |
2534 | ||
2535 | @cindex single character constant | |
2536 | @cindex character, single | |
2537 | @cindex constant, single character | |
2538 | A single character may be written as a single quote immediately | |
2539 | followed by that character. The same escapes apply to characters as | |
2540 | to strings. So if you want to write the character backslash, you | |
2541 | must write @kbd{'\\} where the first @code{\} escapes the second | |
2542 | @code{\}. As you can see, the quote is an acute accent, not a | |
2543 | grave accent. A newline | |
2544 | @ifclear GENERIC | |
2545 | @ifclear abnormal-separator | |
2546 | (or semicolon @samp{;}) | |
2547 | @end ifclear | |
2548 | @ifset abnormal-separator | |
252b5132 RH |
2549 | @ifset H8 |
2550 | (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the | |
7be1c489 | 2551 | Renesas SH) |
252b5132 RH |
2552 | @end ifset |
2553 | @end ifset | |
2554 | @end ifclear | |
2555 | immediately following an acute accent is taken as a literal character | |
2556 | and does not count as the end of a statement. The value of a character | |
2557 | constant in a numeric expression is the machine's byte-wide code for | |
a4fb0134 | 2558 | that character. @command{@value{AS}} assumes your character code is ASCII: |
252b5132 RH |
2559 | @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill |
2560 | ||
2561 | @node Numbers | |
2562 | @subsection Number Constants | |
2563 | ||
2564 | @cindex constants, number | |
2565 | @cindex number constants | |
a4fb0134 | 2566 | @command{@value{AS}} distinguishes three kinds of numbers according to how they |
252b5132 RH |
2567 | are stored in the target machine. @emph{Integers} are numbers that |
2568 | would fit into an @code{int} in the C language. @emph{Bignums} are | |
2569 | integers, but they are stored in more than 32 bits. @emph{Flonums} | |
2570 | are floating point numbers, described below. | |
2571 | ||
2572 | @menu | |
2573 | * Integers:: Integers | |
2574 | * Bignums:: Bignums | |
2575 | * Flonums:: Flonums | |
2576 | @ifclear GENERIC | |
2577 | @ifset I960 | |
2578 | * Bit Fields:: Bit Fields | |
2579 | @end ifset | |
2580 | @end ifclear | |
2581 | @end menu | |
2582 | ||
2583 | @node Integers | |
2584 | @subsubsection Integers | |
2585 | @cindex integers | |
2586 | @cindex constants, integer | |
2587 | ||
2588 | @cindex binary integers | |
2589 | @cindex integers, binary | |
2590 | A binary integer is @samp{0b} or @samp{0B} followed by zero or more of | |
2591 | the binary digits @samp{01}. | |
2592 | ||
2593 | @cindex octal integers | |
2594 | @cindex integers, octal | |
2595 | An octal integer is @samp{0} followed by zero or more of the octal | |
2596 | digits (@samp{01234567}). | |
2597 | ||
2598 | @cindex decimal integers | |
2599 | @cindex integers, decimal | |
2600 | A decimal integer starts with a non-zero digit followed by zero or | |
2601 | more digits (@samp{0123456789}). | |
2602 | ||
2603 | @cindex hexadecimal integers | |
2604 | @cindex integers, hexadecimal | |
2605 | A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or | |
2606 | more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}. | |
2607 | ||
2608 | Integers have the usual values. To denote a negative integer, use | |
2609 | the prefix operator @samp{-} discussed under expressions | |
2610 | (@pxref{Prefix Ops,,Prefix Operators}). | |
2611 | ||
2612 | @node Bignums | |
2613 | @subsubsection Bignums | |
2614 | ||
2615 | @cindex bignums | |
2616 | @cindex constants, bignum | |
2617 | A @dfn{bignum} has the same syntax and semantics as an integer | |
2618 | except that the number (or its negative) takes more than 32 bits to | |
2619 | represent in binary. The distinction is made because in some places | |
2620 | integers are permitted while bignums are not. | |
2621 | ||
2622 | @node Flonums | |
2623 | @subsubsection Flonums | |
2624 | @cindex flonums | |
2625 | @cindex floating point numbers | |
2626 | @cindex constants, floating point | |
2627 | ||
2628 | @cindex precision, floating point | |
2629 | A @dfn{flonum} represents a floating point number. The translation is | |
2630 | indirect: a decimal floating point number from the text is converted by | |
a4fb0134 | 2631 | @command{@value{AS}} to a generic binary floating point number of more than |
252b5132 RH |
2632 | sufficient precision. This generic floating point number is converted |
2633 | to a particular computer's floating point format (or formats) by a | |
a4fb0134 | 2634 | portion of @command{@value{AS}} specialized to that computer. |
252b5132 RH |
2635 | |
2636 | A flonum is written by writing (in order) | |
2637 | @itemize @bullet | |
2638 | @item | |
2639 | The digit @samp{0}. | |
2640 | @ifset HPPA | |
2641 | (@samp{0} is optional on the HPPA.) | |
2642 | @end ifset | |
2643 | ||
2644 | @item | |
a4fb0134 | 2645 | A letter, to tell @command{@value{AS}} the rest of the number is a flonum. |
252b5132 RH |
2646 | @ifset GENERIC |
2647 | @kbd{e} is recommended. Case is not important. | |
2648 | @ignore | |
2649 | @c FIXME: verify if flonum syntax really this vague for most cases | |
2650 | (Any otherwise illegal letter works here, but that might be changed. Vax BSD | |
2651 | 4.2 assembler seems to allow any of @samp{defghDEFGH}.) | |
2652 | @end ignore | |
2653 | ||
7be1c489 | 2654 | On the H8/300, Renesas / SuperH SH, |
252b5132 RH |
2655 | and AMD 29K architectures, the letter must be |
2656 | one of the letters @samp{DFPRSX} (in upper or lower case). | |
2657 | ||
2658 | On the ARC, the letter must be one of the letters @samp{DFRS} | |
2659 | (in upper or lower case). | |
2660 | ||
2661 | On the Intel 960 architecture, the letter must be | |
2662 | one of the letters @samp{DFT} (in upper or lower case). | |
2663 | ||
2664 | On the HPPA architecture, the letter must be @samp{E} (upper case only). | |
2665 | @end ifset | |
2666 | @ifclear GENERIC | |
252b5132 RH |
2667 | @ifset ARC |
2668 | One of the letters @samp{DFRS} (in upper or lower case). | |
2669 | @end ifset | |
2670 | @ifset H8 | |
2671 | One of the letters @samp{DFPRSX} (in upper or lower case). | |
2672 | @end ifset | |
2673 | @ifset HPPA | |
2674 | The letter @samp{E} (upper case only). | |
2675 | @end ifset | |
2676 | @ifset I960 | |
2677 | One of the letters @samp{DFT} (in upper or lower case). | |
2678 | @end ifset | |
2679 | @end ifclear | |
2680 | ||
2681 | @item | |
2682 | An optional sign: either @samp{+} or @samp{-}. | |
2683 | ||
2684 | @item | |
2685 | An optional @dfn{integer part}: zero or more decimal digits. | |
2686 | ||
2687 | @item | |
2688 | An optional @dfn{fractional part}: @samp{.} followed by zero | |
2689 | or more decimal digits. | |
2690 | ||
2691 | @item | |
2692 | An optional exponent, consisting of: | |
2693 | ||
2694 | @itemize @bullet | |
2695 | @item | |
2696 | An @samp{E} or @samp{e}. | |
2697 | @c I can't find a config where "EXP_CHARS" is other than 'eE', but in | |
2698 | @c principle this can perfectly well be different on different targets. | |
2699 | @item | |
2700 | Optional sign: either @samp{+} or @samp{-}. | |
2701 | @item | |
2702 | One or more decimal digits. | |
2703 | @end itemize | |
2704 | ||
2705 | @end itemize | |
2706 | ||
2707 | At least one of the integer part or the fractional part must be | |
2708 | present. The floating point number has the usual base-10 value. | |
2709 | ||
a4fb0134 | 2710 | @command{@value{AS}} does all processing using integers. Flonums are computed |
252b5132 | 2711 | independently of any floating point hardware in the computer running |
a4fb0134 | 2712 | @command{@value{AS}}. |
252b5132 RH |
2713 | |
2714 | @ifclear GENERIC | |
2715 | @ifset I960 | |
2716 | @c Bit fields are written as a general facility but are also controlled | |
2717 | @c by a conditional-compilation flag---which is as of now (21mar91) | |
2718 | @c turned on only by the i960 config of GAS. | |
2719 | @node Bit Fields | |
2720 | @subsubsection Bit Fields | |
2721 | ||
2722 | @cindex bit fields | |
2723 | @cindex constants, bit field | |
2724 | You can also define numeric constants as @dfn{bit fields}. | |
b45619c0 | 2725 | Specify two numbers separated by a colon--- |
252b5132 RH |
2726 | @example |
2727 | @var{mask}:@var{value} | |
2728 | @end example | |
2729 | @noindent | |
a4fb0134 | 2730 | @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and |
252b5132 RH |
2731 | @var{value}. |
2732 | ||
2733 | The resulting number is then packed | |
2734 | @ifset GENERIC | |
2735 | @c this conditional paren in case bit fields turned on elsewhere than 960 | |
2736 | (in host-dependent byte order) | |
2737 | @end ifset | |
2738 | into a field whose width depends on which assembler directive has the | |
2739 | bit-field as its argument. Overflow (a result from the bitwise and | |
2740 | requiring more binary digits to represent) is not an error; instead, | |
2741 | more constants are generated, of the specified width, beginning with the | |
2742 | least significant digits.@refill | |
2743 | ||
2744 | The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long}, | |
2745 | @code{.short}, and @code{.word} accept bit-field arguments. | |
2746 | @end ifset | |
2747 | @end ifclear | |
2748 | ||
2749 | @node Sections | |
2750 | @chapter Sections and Relocation | |
2751 | @cindex sections | |
2752 | @cindex relocation | |
2753 | ||
2754 | @menu | |
2755 | * Secs Background:: Background | |
2756 | * Ld Sections:: Linker Sections | |
2757 | * As Sections:: Assembler Internal Sections | |
2758 | * Sub-Sections:: Sub-Sections | |
2759 | * bss:: bss Section | |
2760 | @end menu | |
2761 | ||
2762 | @node Secs Background | |
2763 | @section Background | |
2764 | ||
2765 | Roughly, a section is a range of addresses, with no gaps; all data | |
2766 | ``in'' those addresses is treated the same for some particular purpose. | |
2767 | For example there may be a ``read only'' section. | |
2768 | ||
2769 | @cindex linker, and assembler | |
2770 | @cindex assembler, and linker | |
2771 | The linker @code{@value{LD}} reads many object files (partial programs) and | |
a4fb0134 | 2772 | combines their contents to form a runnable program. When @command{@value{AS}} |
252b5132 RH |
2773 | emits an object file, the partial program is assumed to start at address 0. |
2774 | @code{@value{LD}} assigns the final addresses for the partial program, so that | |
2775 | different partial programs do not overlap. This is actually an | |
a4fb0134 | 2776 | oversimplification, but it suffices to explain how @command{@value{AS}} uses |
252b5132 RH |
2777 | sections. |
2778 | ||
2779 | @code{@value{LD}} moves blocks of bytes of your program to their run-time | |
2780 | addresses. These blocks slide to their run-time addresses as rigid | |
2781 | units; their length does not change and neither does the order of bytes | |
2782 | within them. Such a rigid unit is called a @emph{section}. Assigning | |
2783 | run-time addresses to sections is called @dfn{relocation}. It includes | |
2784 | the task of adjusting mentions of object-file addresses so they refer to | |
2785 | the proper run-time addresses. | |
2786 | @ifset H8 | |
7be1c489 | 2787 | For the H8/300, and for the Renesas / SuperH SH, |
a4fb0134 | 2788 | @command{@value{AS}} pads sections if needed to |
252b5132 RH |
2789 | ensure they end on a word (sixteen bit) boundary. |
2790 | @end ifset | |
2791 | ||
2792 | @cindex standard assembler sections | |
a4fb0134 | 2793 | An object file written by @command{@value{AS}} has at least three sections, any |
252b5132 RH |
2794 | of which may be empty. These are named @dfn{text}, @dfn{data} and |
2795 | @dfn{bss} sections. | |
2796 | ||
c1253627 | 2797 | @ifset COFF-ELF |
252b5132 | 2798 | @ifset GENERIC |
c1253627 | 2799 | When it generates COFF or ELF output, |
252b5132 | 2800 | @end ifset |
a4fb0134 | 2801 | @command{@value{AS}} can also generate whatever other named sections you specify |
252b5132 RH |
2802 | using the @samp{.section} directive (@pxref{Section,,@code{.section}}). |
2803 | If you do not use any directives that place output in the @samp{.text} | |
2804 | or @samp{.data} sections, these sections still exist, but are empty. | |
2805 | @end ifset | |
2806 | ||
2807 | @ifset HPPA | |
2808 | @ifset GENERIC | |
a4fb0134 | 2809 | When @command{@value{AS}} generates SOM or ELF output for the HPPA, |
252b5132 | 2810 | @end ifset |
a4fb0134 | 2811 | @command{@value{AS}} can also generate whatever other named sections you |
252b5132 RH |
2812 | specify using the @samp{.space} and @samp{.subspace} directives. See |
2813 | @cite{HP9000 Series 800 Assembly Language Reference Manual} | |
2814 | (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace} | |
2815 | assembler directives. | |
2816 | ||
2817 | @ifset SOM | |
a4fb0134 | 2818 | Additionally, @command{@value{AS}} uses different names for the standard |
252b5132 RH |
2819 | text, data, and bss sections when generating SOM output. Program text |
2820 | is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and | |
2821 | BSS into @samp{$BSS$}. | |
2822 | @end ifset | |
2823 | @end ifset | |
2824 | ||
2825 | Within the object file, the text section starts at address @code{0}, the | |
2826 | data section follows, and the bss section follows the data section. | |
2827 | ||
2828 | @ifset HPPA | |
2829 | When generating either SOM or ELF output files on the HPPA, the text | |
2830 | section starts at address @code{0}, the data section at address | |
2831 | @code{0x4000000}, and the bss section follows the data section. | |
2832 | @end ifset | |
2833 | ||
2834 | To let @code{@value{LD}} know which data changes when the sections are | |
a4fb0134 | 2835 | relocated, and how to change that data, @command{@value{AS}} also writes to the |
252b5132 RH |
2836 | object file details of the relocation needed. To perform relocation |
2837 | @code{@value{LD}} must know, each time an address in the object | |
2838 | file is mentioned: | |
2839 | @itemize @bullet | |
2840 | @item | |
2841 | Where in the object file is the beginning of this reference to | |
2842 | an address? | |
2843 | @item | |
2844 | How long (in bytes) is this reference? | |
2845 | @item | |
2846 | Which section does the address refer to? What is the numeric value of | |
2847 | @display | |
2848 | (@var{address}) @minus{} (@var{start-address of section})? | |
2849 | @end display | |
2850 | @item | |
2851 | Is the reference to an address ``Program-Counter relative''? | |
2852 | @end itemize | |
2853 | ||
2854 | @cindex addresses, format of | |
2855 | @cindex section-relative addressing | |
a4fb0134 | 2856 | In fact, every address @command{@value{AS}} ever uses is expressed as |
252b5132 RH |
2857 | @display |
2858 | (@var{section}) + (@var{offset into section}) | |
2859 | @end display | |
2860 | @noindent | |
a4fb0134 | 2861 | Further, most expressions @command{@value{AS}} computes have this section-relative |
252b5132 RH |
2862 | nature. |
2863 | @ifset SOM | |
2864 | (For some object formats, such as SOM for the HPPA, some expressions are | |
2865 | symbol-relative instead.) | |
2866 | @end ifset | |
2867 | ||
2868 | In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset | |
2869 | @var{N} into section @var{secname}.'' | |
2870 | ||
2871 | Apart from text, data and bss sections you need to know about the | |
2872 | @dfn{absolute} section. When @code{@value{LD}} mixes partial programs, | |
2873 | addresses in the absolute section remain unchanged. For example, address | |
2874 | @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by | |
2875 | @code{@value{LD}}. Although the linker never arranges two partial programs' | |
2876 | data sections with overlapping addresses after linking, @emph{by definition} | |
2877 | their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one | |
2878 | part of a program is always the same address when the program is running as | |
2879 | address @code{@{absolute@ 239@}} in any other part of the program. | |
2880 | ||
2881 | The idea of sections is extended to the @dfn{undefined} section. Any | |
2882 | address whose section is unknown at assembly time is by definition | |
2883 | rendered @{undefined @var{U}@}---where @var{U} is filled in later. | |
2884 | Since numbers are always defined, the only way to generate an undefined | |
2885 | address is to mention an undefined symbol. A reference to a named | |
2886 | common block would be such a symbol: its value is unknown at assembly | |
2887 | time so it has section @emph{undefined}. | |
2888 | ||
2889 | By analogy the word @emph{section} is used to describe groups of sections in | |
2890 | the linked program. @code{@value{LD}} puts all partial programs' text | |
2891 | sections in contiguous addresses in the linked program. It is | |
2892 | customary to refer to the @emph{text section} of a program, meaning all | |
2893 | the addresses of all partial programs' text sections. Likewise for | |
2894 | data and bss sections. | |
2895 | ||
2896 | Some sections are manipulated by @code{@value{LD}}; others are invented for | |
a4fb0134 | 2897 | use of @command{@value{AS}} and have no meaning except during assembly. |
252b5132 RH |
2898 | |
2899 | @node Ld Sections | |
2900 | @section Linker Sections | |
2901 | @code{@value{LD}} deals with just four kinds of sections, summarized below. | |
2902 | ||
2903 | @table @strong | |
2904 | ||
c1253627 | 2905 | @ifset COFF-ELF |
252b5132 RH |
2906 | @cindex named sections |
2907 | @cindex sections, named | |
2908 | @item named sections | |
2909 | @end ifset | |
2910 | @ifset aout-bout | |
2911 | @cindex text section | |
2912 | @cindex data section | |
2913 | @itemx text section | |
2914 | @itemx data section | |
2915 | @end ifset | |
a4fb0134 | 2916 | These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as |
252b5132 | 2917 | separate but equal sections. Anything you can say of one section is |
c1253627 NC |
2918 | true of another. |
2919 | @c @ifset aout-bout | |
252b5132 RH |
2920 | When the program is running, however, it is |
2921 | customary for the text section to be unalterable. The | |
2922 | text section is often shared among processes: it contains | |
2923 | instructions, constants and the like. The data section of a running | |
2924 | program is usually alterable: for example, C variables would be stored | |
2925 | in the data section. | |
c1253627 | 2926 | @c @end ifset |
252b5132 RH |
2927 | |
2928 | @cindex bss section | |
2929 | @item bss section | |
2930 | This section contains zeroed bytes when your program begins running. It | |
a349d9dd | 2931 | is used to hold uninitialized variables or common storage. The length of |
252b5132 RH |
2932 | each partial program's bss section is important, but because it starts |
2933 | out containing zeroed bytes there is no need to store explicit zero | |
2934 | bytes in the object file. The bss section was invented to eliminate | |
2935 | those explicit zeros from object files. | |
2936 | ||
2937 | @cindex absolute section | |
2938 | @item absolute section | |
2939 | Address 0 of this section is always ``relocated'' to runtime address 0. | |
2940 | This is useful if you want to refer to an address that @code{@value{LD}} must | |
2941 | not change when relocating. In this sense we speak of absolute | |
2942 | addresses being ``unrelocatable'': they do not change during relocation. | |
2943 | ||
2944 | @cindex undefined section | |
2945 | @item undefined section | |
2946 | This ``section'' is a catch-all for address references to objects not in | |
2947 | the preceding sections. | |
2948 | @c FIXME: ref to some other doc on obj-file formats could go here. | |
2949 | @end table | |
2950 | ||
2951 | @cindex relocation example | |
2952 | An idealized example of three relocatable sections follows. | |
c1253627 | 2953 | @ifset COFF-ELF |
252b5132 RH |
2954 | The example uses the traditional section names @samp{.text} and @samp{.data}. |
2955 | @end ifset | |
2956 | Memory addresses are on the horizontal axis. | |
2957 | ||
2958 | @c TEXI2ROFF-KILL | |
c1253627 | 2959 | @ifnottex |
252b5132 RH |
2960 | @c END TEXI2ROFF-KILL |
2961 | @smallexample | |
2962 | +-----+----+--+ | |
2963 | partial program # 1: |ttttt|dddd|00| | |
2964 | +-----+----+--+ | |
2965 | ||
2966 | text data bss | |
2967 | seg. seg. seg. | |
2968 | ||
2969 | +---+---+---+ | |
2970 | partial program # 2: |TTT|DDD|000| | |
2971 | +---+---+---+ | |
2972 | ||
2973 | +--+---+-----+--+----+---+-----+~~ | |
2974 | linked program: | |TTT|ttttt| |dddd|DDD|00000| | |
2975 | +--+---+-----+--+----+---+-----+~~ | |
2976 | ||
2977 | addresses: 0 @dots{} | |
2978 | @end smallexample | |
2979 | @c TEXI2ROFF-KILL | |
c1253627 | 2980 | @end ifnottex |
252b5132 RH |
2981 | @need 5000 |
2982 | @tex | |
c1253627 | 2983 | \bigskip |
252b5132 RH |
2984 | \line{\it Partial program \#1: \hfil} |
2985 | \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} | |
2986 | \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil} | |
2987 | ||
2988 | \line{\it Partial program \#2: \hfil} | |
2989 | \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} | |
2990 | \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil} | |
2991 | ||
2992 | \line{\it linked program: \hfil} | |
2993 | \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil} | |
2994 | \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt | |
2995 | ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt | |
2996 | DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil} | |
2997 | ||
2998 | \line{\it addresses: \hfil} | |
2999 | \line{0\dots\hfil} | |
3000 | ||
3001 | @end tex | |
3002 | @c END TEXI2ROFF-KILL | |
3003 | ||
3004 | @node As Sections | |
3005 | @section Assembler Internal Sections | |
3006 | ||
3007 | @cindex internal assembler sections | |
3008 | @cindex sections in messages, internal | |
a4fb0134 | 3009 | These sections are meant only for the internal use of @command{@value{AS}}. They |
252b5132 | 3010 | have no meaning at run-time. You do not really need to know about these |
a4fb0134 | 3011 | sections for most purposes; but they can be mentioned in @command{@value{AS}} |
252b5132 | 3012 | warning messages, so it might be helpful to have an idea of their |
a4fb0134 | 3013 | meanings to @command{@value{AS}}. These sections are used to permit the |
252b5132 RH |
3014 | value of every expression in your assembly language program to be a |
3015 | section-relative address. | |
3016 | ||
3017 | @table @b | |
3018 | @cindex assembler internal logic error | |
3019 | @item ASSEMBLER-INTERNAL-LOGIC-ERROR! | |
3020 | An internal assembler logic error has been found. This means there is a | |
3021 | bug in the assembler. | |
3022 | ||
3023 | @cindex expr (internal section) | |
3024 | @item expr section | |
3025 | The assembler stores complex expression internally as combinations of | |
3026 | symbols. When it needs to represent an expression as a symbol, it puts | |
3027 | it in the expr section. | |
3028 | @c FIXME item debug | |
3029 | @c FIXME item transfer[t] vector preload | |
3030 | @c FIXME item transfer[t] vector postload | |
3031 | @c FIXME item register | |
3032 | @end table | |
3033 | ||
3034 | @node Sub-Sections | |
3035 | @section Sub-Sections | |
3036 | ||
3037 | @cindex numbered subsections | |
3038 | @cindex grouping data | |
3039 | @ifset aout-bout | |
3040 | Assembled bytes | |
c1253627 | 3041 | @ifset COFF-ELF |
252b5132 RH |
3042 | conventionally |
3043 | @end ifset | |
3044 | fall into two sections: text and data. | |
3045 | @end ifset | |
3046 | You may have separate groups of | |
3047 | @ifset GENERIC | |
3048 | data in named sections | |
3049 | @end ifset | |
3050 | @ifclear GENERIC | |
3051 | @ifclear aout-bout | |
3052 | data in named sections | |
3053 | @end ifclear | |
3054 | @ifset aout-bout | |
3055 | text or data | |
3056 | @end ifset | |
3057 | @end ifclear | |
3058 | that you want to end up near to each other in the object file, even though they | |
a4fb0134 | 3059 | are not contiguous in the assembler source. @command{@value{AS}} allows you to |
252b5132 RH |
3060 | use @dfn{subsections} for this purpose. Within each section, there can be |
3061 | numbered subsections with values from 0 to 8192. Objects assembled into the | |
3062 | same subsection go into the object file together with other objects in the same | |
3063 | subsection. For example, a compiler might want to store constants in the text | |
3064 | section, but might not want to have them interspersed with the program being | |
3065 | assembled. In this case, the compiler could issue a @samp{.text 0} before each | |
3066 | section of code being output, and a @samp{.text 1} before each group of | |
3067 | constants being output. | |
3068 | ||
3069 | Subsections are optional. If you do not use subsections, everything | |
3070 | goes in subsection number zero. | |
3071 | ||
3072 | @ifset GENERIC | |
3073 | Each subsection is zero-padded up to a multiple of four bytes. | |
3074 | (Subsections may be padded a different amount on different flavors | |
a4fb0134 | 3075 | of @command{@value{AS}}.) |
252b5132 RH |
3076 | @end ifset |
3077 | @ifclear GENERIC | |
3078 | @ifset H8 | |
7be1c489 | 3079 | On the H8/300 platform, each subsection is zero-padded to a word |
252b5132 | 3080 | boundary (two bytes). |
c2dcd04e | 3081 | The same is true on the Renesas SH. |
252b5132 RH |
3082 | @end ifset |
3083 | @ifset I960 | |
3084 | @c FIXME section padding (alignment)? | |
3085 | @c Rich Pixley says padding here depends on target obj code format; that | |
3086 | @c doesn't seem particularly useful to say without further elaboration, | |
3087 | @c so for now I say nothing about it. If this is a generic BFD issue, | |
3088 | @c these paragraphs might need to vanish from this manual, and be | |
3089 | @c discussed in BFD chapter of binutils (or some such). | |
3090 | @end ifset | |
252b5132 RH |
3091 | @end ifclear |
3092 | ||
3093 | Subsections appear in your object file in numeric order, lowest numbered | |
3094 | to highest. (All this to be compatible with other people's assemblers.) | |
3095 | The object file contains no representation of subsections; @code{@value{LD}} and | |
3096 | other programs that manipulate object files see no trace of them. | |
3097 | They just see all your text subsections as a text section, and all your | |
3098 | data subsections as a data section. | |
3099 | ||
3100 | To specify which subsection you want subsequent statements assembled | |
3101 | into, use a numeric argument to specify it, in a @samp{.text | |
3102 | @var{expression}} or a @samp{.data @var{expression}} statement. | |
ed9589d4 | 3103 | @ifset COFF |
252b5132 | 3104 | @ifset GENERIC |
ed9589d4 | 3105 | When generating COFF output, you |
252b5132 RH |
3106 | @end ifset |
3107 | @ifclear GENERIC | |
3108 | You | |
3109 | @end ifclear | |
3110 | can also use an extra subsection | |
3111 | argument with arbitrary named sections: @samp{.section @var{name}, | |
3112 | @var{expression}}. | |
3113 | @end ifset | |
ed9589d4 BW |
3114 | @ifset ELF |
3115 | @ifset GENERIC | |
3116 | When generating ELF output, you | |
3117 | @end ifset | |
3118 | @ifclear GENERIC | |
3119 | You | |
3120 | @end ifclear | |
3121 | can also use the @code{.subsection} directive (@pxref{SubSection}) | |
3122 | to specify a subsection: @samp{.subsection @var{expression}}. | |
3123 | @end ifset | |
96e9638b BW |
3124 | @var{Expression} should be an absolute expression |
3125 | (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0} | |
252b5132 RH |
3126 | is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly |
3127 | begins in @code{text 0}. For instance: | |
3128 | @smallexample | |
3129 | .text 0 # The default subsection is text 0 anyway. | |
3130 | .ascii "This lives in the first text subsection. *" | |
3131 | .text 1 | |
3132 | .ascii "But this lives in the second text subsection." | |
3133 | .data 0 | |
3134 | .ascii "This lives in the data section," | |
3135 | .ascii "in the first data subsection." | |
3136 | .text 0 | |
3137 | .ascii "This lives in the first text section," | |
3138 | .ascii "immediately following the asterisk (*)." | |
3139 | @end smallexample | |
3140 | ||
3141 | Each section has a @dfn{location counter} incremented by one for every byte | |
3142 | assembled into that section. Because subsections are merely a convenience | |
a4fb0134 | 3143 | restricted to @command{@value{AS}} there is no concept of a subsection location |
252b5132 RH |
3144 | counter. There is no way to directly manipulate a location counter---but the |
3145 | @code{.align} directive changes it, and any label definition captures its | |
3146 | current value. The location counter of the section where statements are being | |
3147 | assembled is said to be the @dfn{active} location counter. | |
3148 | ||
3149 | @node bss | |
3150 | @section bss Section | |
3151 | ||
3152 | @cindex bss section | |
3153 | @cindex common variable storage | |
3154 | The bss section is used for local common variable storage. | |
3155 | You may allocate address space in the bss section, but you may | |
3156 | not dictate data to load into it before your program executes. When | |
3157 | your program starts running, all the contents of the bss | |
3158 | section are zeroed bytes. | |
3159 | ||
3160 | The @code{.lcomm} pseudo-op defines a symbol in the bss section; see | |
3161 | @ref{Lcomm,,@code{.lcomm}}. | |
3162 | ||
3163 | The @code{.comm} pseudo-op may be used to declare a common symbol, which is | |
96e9638b | 3164 | another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}. |
252b5132 RH |
3165 | |
3166 | @ifset GENERIC | |
3167 | When assembling for a target which supports multiple sections, such as ELF or | |
3168 | COFF, you may switch into the @code{.bss} section and define symbols as usual; | |
3169 | see @ref{Section,,@code{.section}}. You may only assemble zero values into the | |
3170 | section. Typically the section will only contain symbol definitions and | |
3171 | @code{.skip} directives (@pxref{Skip,,@code{.skip}}). | |
3172 | @end ifset | |
3173 | ||
3174 | @node Symbols | |
3175 | @chapter Symbols | |
3176 | ||
3177 | @cindex symbols | |
3178 | Symbols are a central concept: the programmer uses symbols to name | |
3179 | things, the linker uses symbols to link, and the debugger uses symbols | |
3180 | to debug. | |
3181 | ||
3182 | @quotation | |
3183 | @cindex debuggers, and symbol order | |
a4fb0134 | 3184 | @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in |
252b5132 RH |
3185 | the same order they were declared. This may break some debuggers. |
3186 | @end quotation | |
3187 | ||
3188 | @menu | |
3189 | * Labels:: Labels | |
3190 | * Setting Symbols:: Giving Symbols Other Values | |
3191 | * Symbol Names:: Symbol Names | |
3192 | * Dot:: The Special Dot Symbol | |
3193 | * Symbol Attributes:: Symbol Attributes | |
3194 | @end menu | |
3195 | ||
3196 | @node Labels | |
3197 | @section Labels | |
3198 | ||
3199 | @cindex labels | |
3200 | A @dfn{label} is written as a symbol immediately followed by a colon | |
3201 | @samp{:}. The symbol then represents the current value of the | |
3202 | active location counter, and is, for example, a suitable instruction | |
3203 | operand. You are warned if you use the same symbol to represent two | |
3204 | different locations: the first definition overrides any other | |
3205 | definitions. | |
3206 | ||
3207 | @ifset HPPA | |
3208 | On the HPPA, the usual form for a label need not be immediately followed by a | |
3209 | colon, but instead must start in column zero. Only one label may be defined on | |
a4fb0134 | 3210 | a single line. To work around this, the HPPA version of @command{@value{AS}} also |
252b5132 RH |
3211 | provides a special directive @code{.label} for defining labels more flexibly. |
3212 | @end ifset | |
3213 | ||
3214 | @node Setting Symbols | |
3215 | @section Giving Symbols Other Values | |
3216 | ||
3217 | @cindex assigning values to symbols | |
3218 | @cindex symbol values, assigning | |
3219 | A symbol can be given an arbitrary value by writing a symbol, followed | |
3220 | by an equals sign @samp{=}, followed by an expression | |
3221 | (@pxref{Expressions}). This is equivalent to using the @code{.set} | |
9497f5ac NC |
3222 | directive. @xref{Set,,@code{.set}}. In the same way, using a double |
3223 | equals sign @samp{=}@samp{=} here represents an equivalent of the | |
3224 | @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}. | |
252b5132 RH |
3225 | |
3226 | @node Symbol Names | |
3227 | @section Symbol Names | |
3228 | ||
3229 | @cindex symbol names | |
3230 | @cindex names, symbol | |
3231 | @ifclear SPECIAL-SYMS | |
3232 | Symbol names begin with a letter or with one of @samp{._}. On most | |
3233 | machines, you can also use @code{$} in symbol names; exceptions are | |
3234 | noted in @ref{Machine Dependencies}. That character may be followed by any | |
96e9638b BW |
3235 | string of digits, letters, dollar signs (unless otherwise noted for a |
3236 | particular target machine), and underscores. | |
252b5132 | 3237 | @end ifclear |
252b5132 RH |
3238 | @ifset SPECIAL-SYMS |
3239 | @ifset H8 | |
3240 | Symbol names begin with a letter or with one of @samp{._}. On the | |
7be1c489 | 3241 | Renesas SH you can also use @code{$} in symbol names. That |
c2dcd04e NC |
3242 | character may be followed by any string of digits, letters, dollar signs (save |
3243 | on the H8/300), and underscores. | |
252b5132 RH |
3244 | @end ifset |
3245 | @end ifset | |
3246 | ||
3247 | Case of letters is significant: @code{foo} is a different symbol name | |
3248 | than @code{Foo}. | |
3249 | ||
3250 | Each symbol has exactly one name. Each name in an assembly language program | |
3251 | refers to exactly one symbol. You may use that symbol name any number of times | |
3252 | in a program. | |
3253 | ||
3254 | @subheading Local Symbol Names | |
3255 | ||
3256 | @cindex local symbol names | |
3257 | @cindex symbol names, local | |
ba83aca1 BW |
3258 | A local symbol is any symbol beginning with certain local label prefixes. |
3259 | By default, the local label prefix is @samp{.L} for ELF systems or | |
3260 | @samp{L} for traditional a.out systems, but each target may have its own | |
3261 | set of local label prefixes. | |
3262 | @ifset HPPA | |
3263 | On the HPPA local symbols begin with @samp{L$}. | |
3264 | @end ifset | |
3265 | ||
3266 | Local symbols are defined and used within the assembler, but they are | |
3267 | normally not saved in object files. Thus, they are not visible when debugging. | |
3268 | You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols: | |
3269 | @option{-L}}) to retain the local symbols in the object files. | |
3270 | ||
3271 | @subheading Local Labels | |
3272 | ||
3273 | @cindex local labels | |
252b5132 RH |
3274 | @cindex temporary symbol names |
3275 | @cindex symbol names, temporary | |
ba83aca1 | 3276 | Local labels help compilers and programmers use names temporarily. |
2d5aaba0 NC |
3277 | They create symbols which are guaranteed to be unique over the entire scope of |
3278 | the input source code and which can be referred to by a simple notation. | |
ba83aca1 | 3279 | To define a local label, write a label of the form @samp{@b{N}:} (where @b{N} |
2d5aaba0 | 3280 | represents any positive integer). To refer to the most recent previous |
ba83aca1 | 3281 | definition of that label write @samp{@b{N}b}, using the same number as when |
2d5aaba0 | 3282 | you defined the label. To refer to the next definition of a local label, write |
96e9638b | 3283 | @samp{@b{N}f}---the @samp{b} stands for ``backwards'' and the @samp{f} stands |
2d5aaba0 NC |
3284 | for ``forwards''. |
3285 | ||
3286 | There is no restriction on how you can use these labels, and you can reuse them | |
3287 | too. So that it is possible to repeatedly define the same local label (using | |
3288 | the same number @samp{@b{N}}), although you can only refer to the most recently | |
3289 | defined local label of that number (for a backwards reference) or the next | |
3290 | definition of a specific local label for a forward reference. It is also worth | |
3291 | noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are | |
3292 | implemented in a slightly more efficient manner than the others. | |
3293 | ||
3294 | Here is an example: | |
3295 | ||
3296 | @smallexample | |
3297 | 1: branch 1f | |
3298 | 2: branch 1b | |
3299 | 1: branch 2f | |
3300 | 2: branch 1b | |
3301 | @end smallexample | |
3302 | ||
3303 | Which is the equivalent of: | |
3304 | ||
3305 | @smallexample | |
3306 | label_1: branch label_3 | |
3307 | label_2: branch label_1 | |
3308 | label_3: branch label_4 | |
3309 | label_4: branch label_3 | |
3310 | @end smallexample | |
3311 | ||
ba83aca1 | 3312 | Local label names are only a notational device. They are immediately |
2d5aaba0 | 3313 | transformed into more conventional symbol names before the assembler uses them. |
96e9638b BW |
3314 | The symbol names are stored in the symbol table, appear in error messages, and |
3315 | are optionally emitted to the object file. The names are constructed using | |
3316 | these parts: | |
252b5132 RH |
3317 | |
3318 | @table @code | |
ba83aca1 BW |
3319 | @item @emph{local label prefix} |
3320 | All local symbols begin with the system-specific local label prefix. | |
3321 | Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols | |
3322 | that start with the local label prefix. These labels are | |
252b5132 | 3323 | used for symbols you are never intended to see. If you use the |
a4fb0134 | 3324 | @samp{-L} option then @command{@value{AS}} retains these symbols in the |
252b5132 RH |
3325 | object file. If you also instruct @code{@value{LD}} to retain these symbols, |
3326 | you may use them in debugging. | |
3327 | ||
2d5aaba0 NC |
3328 | @item @var{number} |
3329 | This is the number that was used in the local label definition. So if the | |
3330 | label is written @samp{55:} then the number is @samp{55}. | |
252b5132 | 3331 | |
2d5aaba0 NC |
3332 | @item @kbd{C-B} |
3333 | This unusual character is included so you do not accidentally invent a symbol | |
3334 | of the same name. The character has ASCII value of @samp{\002} (control-B). | |
252b5132 RH |
3335 | |
3336 | @item @emph{ordinal number} | |
2d5aaba0 NC |
3337 | This is a serial number to keep the labels distinct. The first definition of |
3338 | @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the | |
3339 | number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets | |
b45619c0 | 3340 | the number @samp{1} and its 15th definition gets @samp{15} as well. |
252b5132 RH |
3341 | @end table |
3342 | ||
ba83aca1 BW |
3343 | So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and |
3344 | the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}. | |
2d5aaba0 NC |
3345 | |
3346 | @subheading Dollar Local Labels | |
3347 | @cindex dollar local symbols | |
3348 | ||
3349 | @code{@value{AS}} also supports an even more local form of local labels called | |
96e9638b BW |
3350 | dollar labels. These labels go out of scope (i.e., they become undefined) as |
3351 | soon as a non-local label is defined. Thus they remain valid for only a small | |
2d5aaba0 NC |
3352 | region of the input source code. Normal local labels, by contrast, remain in |
3353 | scope for the entire file, or until they are redefined by another occurrence of | |
3354 | the same local label. | |
3355 | ||
3356 | Dollar labels are defined in exactly the same way as ordinary local labels, | |
3357 | except that instead of being terminated by a colon, they are terminated by a | |
96e9638b | 3358 | dollar sign, e.g., @samp{@b{55$}}. |
2d5aaba0 NC |
3359 | |
3360 | They can also be distinguished from ordinary local labels by their transformed | |
96e9638b BW |
3361 | names which use ASCII character @samp{\001} (control-A) as the magic character |
3362 | to distinguish them from ordinary labels. For example, the fifth definition of | |
ba83aca1 | 3363 | @samp{6$} may be named @samp{.L6@kbd{C-A}5}. |
252b5132 RH |
3364 | |
3365 | @node Dot | |
3366 | @section The Special Dot Symbol | |
3367 | ||
3368 | @cindex dot (symbol) | |
3369 | @cindex @code{.} (symbol) | |
3370 | @cindex current address | |
3371 | @cindex location counter | |
3372 | The special symbol @samp{.} refers to the current address that | |
a4fb0134 | 3373 | @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin: |
252b5132 RH |
3374 | .long .} defines @code{melvin} to contain its own address. |
3375 | Assigning a value to @code{.} is treated the same as a @code{.org} | |
3376 | directive. Thus, the expression @samp{.=.+4} is the same as saying | |
3377 | @ifclear no-space-dir | |
3378 | @samp{.space 4}. | |
3379 | @end ifclear | |
252b5132 RH |
3380 | |
3381 | @node Symbol Attributes | |
3382 | @section Symbol Attributes | |
3383 | ||
3384 | @cindex symbol attributes | |
3385 | @cindex attributes, symbol | |
3386 | Every symbol has, as well as its name, the attributes ``Value'' and | |
3387 | ``Type''. Depending on output format, symbols can also have auxiliary | |
3388 | attributes. | |
3389 | @ifset INTERNALS | |
3390 | The detailed definitions are in @file{a.out.h}. | |
3391 | @end ifset | |
3392 | ||
a4fb0134 | 3393 | If you use a symbol without defining it, @command{@value{AS}} assumes zero for |
252b5132 RH |
3394 | all these attributes, and probably won't warn you. This makes the |
3395 | symbol an externally defined symbol, which is generally what you | |
3396 | would want. | |
3397 | ||
3398 | @menu | |
3399 | * Symbol Value:: Value | |
3400 | * Symbol Type:: Type | |
3401 | @ifset aout-bout | |
3402 | @ifset GENERIC | |
3403 | * a.out Symbols:: Symbol Attributes: @code{a.out} | |
3404 | @end ifset | |
3405 | @ifclear GENERIC | |
3406 | @ifclear BOUT | |
3407 | * a.out Symbols:: Symbol Attributes: @code{a.out} | |
3408 | @end ifclear | |
3409 | @ifset BOUT | |
3410 | * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out} | |
3411 | @end ifset | |
3412 | @end ifclear | |
3413 | @end ifset | |
3414 | @ifset COFF | |
3415 | * COFF Symbols:: Symbol Attributes for COFF | |
3416 | @end ifset | |
3417 | @ifset SOM | |
3418 | * SOM Symbols:: Symbol Attributes for SOM | |
3419 | @end ifset | |
3420 | @end menu | |
3421 | ||
3422 | @node Symbol Value | |
3423 | @subsection Value | |
3424 | ||
3425 | @cindex value of a symbol | |
3426 | @cindex symbol value | |
3427 | The value of a symbol is (usually) 32 bits. For a symbol which labels a | |
3428 | location in the text, data, bss or absolute sections the value is the | |
3429 | number of addresses from the start of that section to the label. | |
3430 | Naturally for text, data and bss sections the value of a symbol changes | |
3431 | as @code{@value{LD}} changes section base addresses during linking. Absolute | |
3432 | symbols' values do not change during linking: that is why they are | |
3433 | called absolute. | |
3434 | ||
3435 | The value of an undefined symbol is treated in a special way. If it is | |
3436 | 0 then the symbol is not defined in this assembler source file, and | |
3437 | @code{@value{LD}} tries to determine its value from other files linked into the | |
3438 | same program. You make this kind of symbol simply by mentioning a symbol | |
3439 | name without defining it. A non-zero value represents a @code{.comm} | |
3440 | common declaration. The value is how much common storage to reserve, in | |
3441 | bytes (addresses). The symbol refers to the first address of the | |
3442 | allocated storage. | |
3443 | ||
3444 | @node Symbol Type | |
3445 | @subsection Type | |
3446 | ||
3447 | @cindex type of a symbol | |
3448 | @cindex symbol type | |
3449 | The type attribute of a symbol contains relocation (section) | |
3450 | information, any flag settings indicating that a symbol is external, and | |
3451 | (optionally), other information for linkers and debuggers. The exact | |
3452 | format depends on the object-code output format in use. | |
3453 | ||
3454 | @ifset aout-bout | |
3455 | @ifclear GENERIC | |
3456 | @ifset BOUT | |
3457 | @c The following avoids a "widow" subsection title. @group would be | |
3458 | @c better if it were available outside examples. | |
3459 | @need 1000 | |
3460 | @node a.out Symbols | |
3461 | @subsection Symbol Attributes: @code{a.out}, @code{b.out} | |
3462 | ||
3463 | @cindex @code{b.out} symbol attributes | |
3464 | @cindex symbol attributes, @code{b.out} | |
a4fb0134 | 3465 | These symbol attributes appear only when @command{@value{AS}} is configured for |
252b5132 RH |
3466 | one of the Berkeley-descended object output formats---@code{a.out} or |
3467 | @code{b.out}. | |
3468 | ||
3469 | @end ifset | |
3470 | @ifclear BOUT | |
3471 | @node a.out Symbols | |
3472 | @subsection Symbol Attributes: @code{a.out} | |
3473 | ||
3474 | @cindex @code{a.out} symbol attributes | |
3475 | @cindex symbol attributes, @code{a.out} | |
3476 | ||
3477 | @end ifclear | |
3478 | @end ifclear | |
3479 | @ifset GENERIC | |
3480 | @node a.out Symbols | |
3481 | @subsection Symbol Attributes: @code{a.out} | |
3482 | ||
3483 | @cindex @code{a.out} symbol attributes | |
3484 | @cindex symbol attributes, @code{a.out} | |
3485 | ||
3486 | @end ifset | |
3487 | @menu | |
3488 | * Symbol Desc:: Descriptor | |
3489 | * Symbol Other:: Other | |
3490 | @end menu | |
3491 | ||
3492 | @node Symbol Desc | |
3493 | @subsubsection Descriptor | |
3494 | ||
3495 | @cindex descriptor, of @code{a.out} symbol | |
3496 | This is an arbitrary 16-bit value. You may establish a symbol's | |
3497 | descriptor value by using a @code{.desc} statement | |
3498 | (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to | |
a4fb0134 | 3499 | @command{@value{AS}}. |
252b5132 RH |
3500 | |
3501 | @node Symbol Other | |
3502 | @subsubsection Other | |
3503 | ||
3504 | @cindex other attribute, of @code{a.out} symbol | |
a4fb0134 | 3505 | This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}. |
252b5132 RH |
3506 | @end ifset |
3507 | ||
3508 | @ifset COFF | |
3509 | @node COFF Symbols | |
3510 | @subsection Symbol Attributes for COFF | |
3511 | ||
3512 | @cindex COFF symbol attributes | |
3513 | @cindex symbol attributes, COFF | |
3514 | ||
3515 | The COFF format supports a multitude of auxiliary symbol attributes; | |
3516 | like the primary symbol attributes, they are set between @code{.def} and | |
3517 | @code{.endef} directives. | |
3518 | ||
3519 | @subsubsection Primary Attributes | |
3520 | ||
3521 | @cindex primary attributes, COFF symbols | |
3522 | The symbol name is set with @code{.def}; the value and type, | |
3523 | respectively, with @code{.val} and @code{.type}. | |
3524 | ||
3525 | @subsubsection Auxiliary Attributes | |
3526 | ||
3527 | @cindex auxiliary attributes, COFF symbols | |
a4fb0134 | 3528 | The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl}, |
c87db184 CF |
3529 | @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol |
3530 | table information for COFF. | |
252b5132 RH |
3531 | @end ifset |
3532 | ||
3533 | @ifset SOM | |
3534 | @node SOM Symbols | |
3535 | @subsection Symbol Attributes for SOM | |
3536 | ||
3537 | @cindex SOM symbol attributes | |
3538 | @cindex symbol attributes, SOM | |
3539 | ||
3540 | The SOM format for the HPPA supports a multitude of symbol attributes set with | |
3541 | the @code{.EXPORT} and @code{.IMPORT} directives. | |
3542 | ||
3543 | The attributes are described in @cite{HP9000 Series 800 Assembly | |
3544 | Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and | |
3545 | @code{EXPORT} assembler directive documentation. | |
3546 | @end ifset | |
3547 | ||
3548 | @node Expressions | |
3549 | @chapter Expressions | |
3550 | ||
3551 | @cindex expressions | |
3552 | @cindex addresses | |
3553 | @cindex numeric values | |
3554 | An @dfn{expression} specifies an address or numeric value. | |
3555 | Whitespace may precede and/or follow an expression. | |
3556 | ||
3557 | The result of an expression must be an absolute number, or else an offset into | |
3558 | a particular section. If an expression is not absolute, and there is not | |
a4fb0134 | 3559 | enough information when @command{@value{AS}} sees the expression to know its |
252b5132 RH |
3560 | section, a second pass over the source program might be necessary to interpret |
3561 | the expression---but the second pass is currently not implemented. | |
a4fb0134 | 3562 | @command{@value{AS}} aborts with an error message in this situation. |
252b5132 RH |
3563 | |
3564 | @menu | |
3565 | * Empty Exprs:: Empty Expressions | |
3566 | * Integer Exprs:: Integer Expressions | |
3567 | @end menu | |
3568 | ||
3569 | @node Empty Exprs | |
3570 | @section Empty Expressions | |
3571 | ||
3572 | @cindex empty expressions | |
3573 | @cindex expressions, empty | |
3574 | An empty expression has no value: it is just whitespace or null. | |
3575 | Wherever an absolute expression is required, you may omit the | |
a4fb0134 | 3576 | expression, and @command{@value{AS}} assumes a value of (absolute) 0. This |
252b5132 RH |
3577 | is compatible with other assemblers. |
3578 | ||
3579 | @node Integer Exprs | |
3580 | @section Integer Expressions | |
3581 | ||
3582 | @cindex integer expressions | |
3583 | @cindex expressions, integer | |
3584 | An @dfn{integer expression} is one or more @emph{arguments} delimited | |
3585 | by @emph{operators}. | |
3586 | ||
3587 | @menu | |
3588 | * Arguments:: Arguments | |
3589 | * Operators:: Operators | |
3590 | * Prefix Ops:: Prefix Operators | |
3591 | * Infix Ops:: Infix Operators | |
3592 | @end menu | |
3593 | ||
3594 | @node Arguments | |
3595 | @subsection Arguments | |
3596 | ||
3597 | @cindex expression arguments | |
3598 | @cindex arguments in expressions | |
3599 | @cindex operands in expressions | |
3600 | @cindex arithmetic operands | |
3601 | @dfn{Arguments} are symbols, numbers or subexpressions. In other | |
3602 | contexts arguments are sometimes called ``arithmetic operands''. In | |
3603 | this manual, to avoid confusing them with the ``instruction operands'' of | |
3604 | the machine language, we use the term ``argument'' to refer to parts of | |
3605 | expressions only, reserving the word ``operand'' to refer only to machine | |
3606 | instruction operands. | |
3607 | ||
3608 | Symbols are evaluated to yield @{@var{section} @var{NNN}@} where | |
3609 | @var{section} is one of text, data, bss, absolute, | |
3610 | or undefined. @var{NNN} is a signed, 2's complement 32 bit | |
3611 | integer. | |
3612 | ||
3613 | Numbers are usually integers. | |
3614 | ||
3615 | A number can be a flonum or bignum. In this case, you are warned | |
a4fb0134 | 3616 | that only the low order 32 bits are used, and @command{@value{AS}} pretends |
252b5132 RH |
3617 | these 32 bits are an integer. You may write integer-manipulating |
3618 | instructions that act on exotic constants, compatible with other | |
3619 | assemblers. | |
3620 | ||
3621 | @cindex subexpressions | |
3622 | Subexpressions are a left parenthesis @samp{(} followed by an integer | |
3623 | expression, followed by a right parenthesis @samp{)}; or a prefix | |
3624 | operator followed by an argument. | |
3625 | ||
3626 | @node Operators | |
3627 | @subsection Operators | |
3628 | ||
3629 | @cindex operators, in expressions | |
3630 | @cindex arithmetic functions | |
3631 | @cindex functions, in expressions | |
3632 | @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix | |
3633 | operators are followed by an argument. Infix operators appear | |
3634 | between their arguments. Operators may be preceded and/or followed by | |
3635 | whitespace. | |
3636 | ||
3637 | @node Prefix Ops | |
3638 | @subsection Prefix Operator | |
3639 | ||
3640 | @cindex prefix operators | |
a4fb0134 | 3641 | @command{@value{AS}} has the following @dfn{prefix operators}. They each take |
252b5132 RH |
3642 | one argument, which must be absolute. |
3643 | ||
3644 | @c the tex/end tex stuff surrounding this small table is meant to make | |
3645 | @c it align, on the printed page, with the similar table in the next | |
3646 | @c section (which is inside an enumerate). | |
3647 | @tex | |
3648 | \global\advance\leftskip by \itemindent | |
3649 | @end tex | |
3650 | ||
3651 | @table @code | |
3652 | @item - | |
3653 | @dfn{Negation}. Two's complement negation. | |
3654 | @item ~ | |
3655 | @dfn{Complementation}. Bitwise not. | |
3656 | @end table | |
3657 | ||
3658 | @tex | |
3659 | \global\advance\leftskip by -\itemindent | |
3660 | @end tex | |
3661 | ||
3662 | @node Infix Ops | |
3663 | @subsection Infix Operators | |
3664 | ||
3665 | @cindex infix operators | |
3666 | @cindex operators, permitted arguments | |
3667 | @dfn{Infix operators} take two arguments, one on either side. Operators | |
3668 | have precedence, but operations with equal precedence are performed left | |
a4fb0134 | 3669 | to right. Apart from @code{+} or @option{-}, both arguments must be |
252b5132 RH |
3670 | absolute, and the result is absolute. |
3671 | ||
3672 | @enumerate | |
3673 | @cindex operator precedence | |
3674 | @cindex precedence of operators | |
3675 | ||
3676 | @item | |
3677 | Highest Precedence | |
3678 | ||
3679 | @table @code | |
3680 | @item * | |
3681 | @dfn{Multiplication}. | |
3682 | ||
3683 | @item / | |
3684 | @dfn{Division}. Truncation is the same as the C operator @samp{/} | |
3685 | ||
3686 | @item % | |
3687 | @dfn{Remainder}. | |
3688 | ||
d1eac9d9 | 3689 | @item << |
252b5132 RH |
3690 | @dfn{Shift Left}. Same as the C operator @samp{<<}. |
3691 | ||
d1eac9d9 | 3692 | @item >> |
252b5132 RH |
3693 | @dfn{Shift Right}. Same as the C operator @samp{>>}. |
3694 | @end table | |
3695 | ||
3696 | @item | |
3697 | Intermediate precedence | |
3698 | ||
3699 | @table @code | |
3700 | @item | | |
3701 | ||
3702 | @dfn{Bitwise Inclusive Or}. | |
3703 | ||
3704 | @item & | |
3705 | @dfn{Bitwise And}. | |
3706 | ||
3707 | @item ^ | |
3708 | @dfn{Bitwise Exclusive Or}. | |
3709 | ||
3710 | @item ! | |
3711 | @dfn{Bitwise Or Not}. | |
3712 | @end table | |
3713 | ||
3714 | @item | |
b131d4dc | 3715 | Low Precedence |
252b5132 RH |
3716 | |
3717 | @table @code | |
3718 | @cindex addition, permitted arguments | |
3719 | @cindex plus, permitted arguments | |
3720 | @cindex arguments for addition | |
3721 | @item + | |
3722 | @dfn{Addition}. If either argument is absolute, the result has the section of | |
3723 | the other argument. You may not add together arguments from different | |
3724 | sections. | |
3725 | ||
3726 | @cindex subtraction, permitted arguments | |
3727 | @cindex minus, permitted arguments | |
3728 | @cindex arguments for subtraction | |
3729 | @item - | |
3730 | @dfn{Subtraction}. If the right argument is absolute, the | |
3731 | result has the section of the left argument. | |
3732 | If both arguments are in the same section, the result is absolute. | |
3733 | You may not subtract arguments from different sections. | |
3734 | @c FIXME is there still something useful to say about undefined - undefined ? | |
b131d4dc NC |
3735 | |
3736 | @cindex comparison expressions | |
3737 | @cindex expressions, comparison | |
3738 | @item == | |
3739 | @dfn{Is Equal To} | |
3740 | @item <> | |
723a8472 | 3741 | @itemx != |
b131d4dc NC |
3742 | @dfn{Is Not Equal To} |
3743 | @item < | |
3744 | @dfn{Is Less Than} | |
d1eac9d9 | 3745 | @item > |
b131d4dc | 3746 | @dfn{Is Greater Than} |
d1eac9d9 | 3747 | @item >= |
b131d4dc | 3748 | @dfn{Is Greater Than Or Equal To} |
d1eac9d9 | 3749 | @item <= |
b131d4dc NC |
3750 | @dfn{Is Less Than Or Equal To} |
3751 | ||
3752 | The comparison operators can be used as infix operators. A true results has a | |
3753 | value of -1 whereas a false result has a value of 0. Note, these operators | |
3754 | perform signed comparisons. | |
3755 | @end table | |
3756 | ||
3757 | @item Lowest Precedence | |
3758 | ||
3759 | @table @code | |
3760 | @item && | |
3761 | @dfn{Logical And}. | |
3762 | ||
3763 | @item || | |
3764 | @dfn{Logical Or}. | |
3765 | ||
3766 | These two logical operations can be used to combine the results of sub | |
3767 | expressions. Note, unlike the comparison operators a true result returns a | |
3768 | value of 1 but a false results does still return 0. Also note that the logical | |
3769 | or operator has a slightly lower precedence than logical and. | |
3770 | ||
252b5132 RH |
3771 | @end table |
3772 | @end enumerate | |
3773 | ||
3774 | In short, it's only meaningful to add or subtract the @emph{offsets} in an | |
3775 | address; you can only have a defined section in one of the two arguments. | |
3776 | ||
3777 | @node Pseudo Ops | |
3778 | @chapter Assembler Directives | |
3779 | ||
3780 | @cindex directives, machine independent | |
3781 | @cindex pseudo-ops, machine independent | |
3782 | @cindex machine independent directives | |
3783 | All assembler directives have names that begin with a period (@samp{.}). | |
3784 | The rest of the name is letters, usually in lower case. | |
3785 | ||
3786 | This chapter discusses directives that are available regardless of the | |
3787 | target machine configuration for the @sc{gnu} assembler. | |
3788 | @ifset GENERIC | |
3789 | Some machine configurations provide additional directives. | |
3790 | @xref{Machine Dependencies}. | |
3791 | @end ifset | |
3792 | @ifclear GENERIC | |
3793 | @ifset machine-directives | |
96e9638b | 3794 | @xref{Machine Dependencies}, for additional directives. |
252b5132 RH |
3795 | @end ifset |
3796 | @end ifclear | |
3797 | ||
3798 | @menu | |
3799 | * Abort:: @code{.abort} | |
3800 | @ifset COFF | |
38a57ae7 | 3801 | * ABORT (COFF):: @code{.ABORT} |
252b5132 | 3802 | @end ifset |
f0dc282c | 3803 | |
252b5132 | 3804 | * Align:: @code{.align @var{abs-expr} , @var{abs-expr}} |
caa32fe5 | 3805 | * Altmacro:: @code{.altmacro} |
252b5132 RH |
3806 | * Ascii:: @code{.ascii "@var{string}"}@dots{} |
3807 | * Asciz:: @code{.asciz "@var{string}"}@dots{} | |
3808 | * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}} | |
3809 | * Byte:: @code{.byte @var{expressions}} | |
3810 | * Comm:: @code{.comm @var{symbol} , @var{length} } | |
54cfded0 | 3811 | |
4b7d318b | 3812 | * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc. |
54cfded0 | 3813 | |
252b5132 RH |
3814 | * Data:: @code{.data @var{subsection}} |
3815 | @ifset COFF | |
3816 | * Def:: @code{.def @var{name}} | |
3817 | @end ifset | |
3818 | @ifset aout-bout | |
3819 | * Desc:: @code{.desc @var{symbol}, @var{abs-expression}} | |
3820 | @end ifset | |
3821 | @ifset COFF | |
3822 | * Dim:: @code{.dim} | |
3823 | @end ifset | |
f0dc282c | 3824 | |
252b5132 RH |
3825 | * Double:: @code{.double @var{flonums}} |
3826 | * Eject:: @code{.eject} | |
3827 | * Else:: @code{.else} | |
3fd9f047 | 3828 | * Elseif:: @code{.elseif} |
252b5132 RH |
3829 | * End:: @code{.end} |
3830 | @ifset COFF | |
3831 | * Endef:: @code{.endef} | |
3832 | @end ifset | |
f0dc282c | 3833 | |
252b5132 RH |
3834 | * Endfunc:: @code{.endfunc} |
3835 | * Endif:: @code{.endif} | |
3836 | * Equ:: @code{.equ @var{symbol}, @var{expression}} | |
3837 | * Equiv:: @code{.equiv @var{symbol}, @var{expression}} | |
9497f5ac | 3838 | * Eqv:: @code{.eqv @var{symbol}, @var{expression}} |
252b5132 | 3839 | * Err:: @code{.err} |
d190d046 | 3840 | * Error:: @code{.error @var{string}} |
252b5132 RH |
3841 | * Exitm:: @code{.exitm} |
3842 | * Extern:: @code{.extern} | |
3843 | * Fail:: @code{.fail} | |
3844 | @ifclear no-file-dir | |
3845 | * File:: @code{.file @var{string}} | |
3846 | @end ifclear | |
f0dc282c | 3847 | |
252b5132 RH |
3848 | * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}} |
3849 | * Float:: @code{.float @var{flonums}} | |
3850 | * Func:: @code{.func} | |
3851 | * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}} | |
c91d2e08 | 3852 | @ifset ELF |
3a99f02f | 3853 | * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}} |
c91d2e08 NC |
3854 | * Hidden:: @code{.hidden @var{names}} |
3855 | @end ifset | |
f0dc282c | 3856 | |
252b5132 RH |
3857 | * hword:: @code{.hword @var{expressions}} |
3858 | * Ident:: @code{.ident} | |
3859 | * If:: @code{.if @var{absolute expression}} | |
7e005732 | 3860 | * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]} |
252b5132 RH |
3861 | * Include:: @code{.include "@var{file}"} |
3862 | * Int:: @code{.int @var{expressions}} | |
c91d2e08 NC |
3863 | @ifset ELF |
3864 | * Internal:: @code{.internal @var{names}} | |
3865 | @end ifset | |
f0dc282c | 3866 | |
252b5132 RH |
3867 | * Irp:: @code{.irp @var{symbol},@var{values}}@dots{} |
3868 | * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{} | |
3869 | * Lcomm:: @code{.lcomm @var{symbol} , @var{length}} | |
3870 | * Lflags:: @code{.lflags} | |
3871 | @ifclear no-line-dir | |
3872 | * Line:: @code{.line @var{line-number}} | |
3873 | @end ifclear | |
f0dc282c | 3874 | |
252b5132 RH |
3875 | * Linkonce:: @code{.linkonce [@var{type}]} |
3876 | * List:: @code{.list} | |
bd0eb99b RH |
3877 | * Ln:: @code{.ln @var{line-number}} |
3878 | ||
3879 | * LNS directives:: @code{.file}, @code{.loc}, etc. | |
3880 | ||
252b5132 RH |
3881 | * Long:: @code{.long @var{expressions}} |
3882 | @ignore | |
3883 | * Lsym:: @code{.lsym @var{symbol}, @var{expression}} | |
3884 | @end ignore | |
f0dc282c | 3885 | |
252b5132 RH |
3886 | * Macro:: @code{.macro @var{name} @var{args}}@dots{} |
3887 | * MRI:: @code{.mri @var{val}} | |
caa32fe5 | 3888 | * Noaltmacro:: @code{.noaltmacro} |
252b5132 RH |
3889 | * Nolist:: @code{.nolist} |
3890 | * Octa:: @code{.octa @var{bignums}} | |
85234291 L |
3891 | * Org:: @code{.org @var{new-lc}, @var{fill}} |
3892 | * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} | |
c91d2e08 NC |
3893 | @ifset ELF |
3894 | * PopSection:: @code{.popsection} | |
3895 | * Previous:: @code{.previous} | |
3896 | @end ifset | |
f0dc282c | 3897 | |
252b5132 | 3898 | * Print:: @code{.print @var{string}} |
c91d2e08 NC |
3899 | @ifset ELF |
3900 | * Protected:: @code{.protected @var{names}} | |
3901 | @end ifset | |
f0dc282c | 3902 | |
252b5132 RH |
3903 | * Psize:: @code{.psize @var{lines}, @var{columns}} |
3904 | * Purgem:: @code{.purgem @var{name}} | |
c91d2e08 NC |
3905 | @ifset ELF |
3906 | * PushSection:: @code{.pushsection @var{name}} | |
3907 | @end ifset | |
f0dc282c | 3908 | |
252b5132 | 3909 | * Quad:: @code{.quad @var{bignums}} |
05e9452c | 3910 | * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]} |
252b5132 RH |
3911 | * Rept:: @code{.rept @var{count}} |
3912 | * Sbttl:: @code{.sbttl "@var{subheading}"} | |
3913 | @ifset COFF | |
3914 | * Scl:: @code{.scl @var{class}} | |
c1253627 NC |
3915 | @end ifset |
3916 | @ifset COFF-ELF | |
7337fc21 | 3917 | * Section:: @code{.section @var{name}[, @var{flags}]} |
252b5132 | 3918 | @end ifset |
f0dc282c | 3919 | |
252b5132 RH |
3920 | * Set:: @code{.set @var{symbol}, @var{expression}} |
3921 | * Short:: @code{.short @var{expressions}} | |
3922 | * Single:: @code{.single @var{flonums}} | |
c1253627 | 3923 | @ifset COFF-ELF |
c91d2e08 | 3924 | * Size:: @code{.size [@var{name} , @var{expression}]} |
c1253627 NC |
3925 | @end ifset |
3926 | ||
252b5132 RH |
3927 | * Skip:: @code{.skip @var{size} , @var{fill}} |
3928 | * Sleb128:: @code{.sleb128 @var{expressions}} | |
3929 | * Space:: @code{.space @var{size} , @var{fill}} | |
3930 | @ifset have-stabs | |
3931 | * Stab:: @code{.stabd, .stabn, .stabs} | |
3932 | @end ifset | |
f0dc282c | 3933 | |
38a57ae7 | 3934 | * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"} |
252b5132 RH |
3935 | * Struct:: @code{.struct @var{expression}} |
3936 | @ifset ELF | |
c91d2e08 | 3937 | * SubSection:: @code{.subsection} |
252b5132 RH |
3938 | * Symver:: @code{.symver @var{name},@var{name2@@nodename}} |
3939 | @end ifset | |
f0dc282c | 3940 | |
252b5132 RH |
3941 | @ifset COFF |
3942 | * Tag:: @code{.tag @var{structname}} | |
3943 | @end ifset | |
f0dc282c | 3944 | |
252b5132 RH |
3945 | * Text:: @code{.text @var{subsection}} |
3946 | * Title:: @code{.title "@var{heading}"} | |
c1253627 | 3947 | @ifset COFF-ELF |
c91d2e08 | 3948 | * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>} |
c1253627 NC |
3949 | @end ifset |
3950 | ||
c91d2e08 | 3951 | * Uleb128:: @code{.uleb128 @var{expressions}} |
252b5132 | 3952 | @ifset COFF |
252b5132 RH |
3953 | * Val:: @code{.val @var{addr}} |
3954 | @end ifset | |
f0dc282c | 3955 | |
2e13b764 | 3956 | @ifset ELF |
c91d2e08 | 3957 | * Version:: @code{.version "@var{string}"} |
c91d2e08 NC |
3958 | * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}} |
3959 | * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}} | |
2e13b764 | 3960 | @end ifset |
f0dc282c | 3961 | |
d190d046 | 3962 | * Warning:: @code{.warning @var{string}} |
c87db184 | 3963 | * Weak:: @code{.weak @var{names}} |
06e77878 | 3964 | * Weakref:: @code{.weakref @var{alias}, @var{symbol}} |
252b5132 RH |
3965 | * Word:: @code{.word @var{expressions}} |
3966 | * Deprecated:: Deprecated Directives | |
3967 | @end menu | |
3968 | ||
3969 | @node Abort | |
3970 | @section @code{.abort} | |
3971 | ||
3972 | @cindex @code{abort} directive | |
3973 | @cindex stopping the assembly | |
3974 | This directive stops the assembly immediately. It is for | |
3975 | compatibility with other assemblers. The original idea was that the | |
3976 | assembly language source would be piped into the assembler. If the sender | |
a4fb0134 | 3977 | of the source quit, it could use this directive tells @command{@value{AS}} to |
252b5132 RH |
3978 | quit also. One day @code{.abort} will not be supported. |
3979 | ||
3980 | @ifset COFF | |
370b66a1 CD |
3981 | @node ABORT (COFF) |
3982 | @section @code{.ABORT} (COFF) | |
252b5132 RH |
3983 | |
3984 | @cindex @code{ABORT} directive | |
a4fb0134 | 3985 | When producing COFF output, @command{@value{AS}} accepts this directive as a |
252b5132 RH |
3986 | synonym for @samp{.abort}. |
3987 | ||
3988 | @ifset BOUT | |
a4fb0134 | 3989 | When producing @code{b.out} output, @command{@value{AS}} accepts this directive, |
252b5132 RH |
3990 | but ignores it. |
3991 | @end ifset | |
3992 | @end ifset | |
3993 | ||
3994 | @node Align | |
3995 | @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} | |
3996 | ||
3997 | @cindex padding the location counter | |
3998 | @cindex @code{align} directive | |
3999 | Pad the location counter (in the current subsection) to a particular storage | |
4000 | boundary. The first expression (which must be absolute) is the alignment | |
4001 | required, as described below. | |
4002 | ||
4003 | The second expression (also absolute) gives the fill value to be stored in the | |
4004 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
4005 | padding bytes are normally zero. However, on some systems, if the section is | |
4006 | marked as containing code and the fill value is omitted, the space is filled | |
4007 | with no-op instructions. | |
4008 | ||
4009 | The third expression is also absolute, and is also optional. If it is present, | |
4010 | it is the maximum number of bytes that should be skipped by this alignment | |
4011 | directive. If doing the alignment would require skipping more bytes than the | |
4012 | specified maximum, then the alignment is not done at all. You can omit the | |
4013 | fill value (the second argument) entirely by simply using two commas after the | |
4014 | required alignment; this can be useful if you want the alignment to be filled | |
4015 | with no-op instructions when appropriate. | |
4016 | ||
4017 | The way the required alignment is specified varies from system to system. | |
7be1c489 | 4018 | For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32, |
60946ad0 | 4019 | s390, sparc, tic4x, tic80 and xtensa, the first expression is the |
252b5132 RH |
4020 | alignment request in bytes. For example @samp{.align 8} advances |
4021 | the location counter until it is a multiple of 8. If the location counter | |
60946ad0 AM |
4022 | is already a multiple of 8, no change is needed. For the tic54x, the |
4023 | first expression is the alignment request in words. | |
252b5132 | 4024 | |
9e9a9798 | 4025 | For other systems, including ppc, i386 using a.out format, arm and |
adcf07e6 | 4026 | strongarm, it is the |
252b5132 RH |
4027 | number of low-order zero bits the location counter must have after |
4028 | advancement. For example @samp{.align 3} advances the location | |
4029 | counter until it a multiple of 8. If the location counter is already a | |
4030 | multiple of 8, no change is needed. | |
4031 | ||
4032 | This inconsistency is due to the different behaviors of the various | |
4033 | native assemblers for these systems which GAS must emulate. | |
4034 | GAS also provides @code{.balign} and @code{.p2align} directives, | |
4035 | described later, which have a consistent behavior across all | |
4036 | architectures (but are specific to GAS). | |
4037 | ||
4038 | @node Ascii | |
4039 | @section @code{.ascii "@var{string}"}@dots{} | |
4040 | ||
4041 | @cindex @code{ascii} directive | |
4042 | @cindex string literals | |
4043 | @code{.ascii} expects zero or more string literals (@pxref{Strings}) | |
4044 | separated by commas. It assembles each string (with no automatic | |
4045 | trailing zero byte) into consecutive addresses. | |
4046 | ||
4047 | @node Asciz | |
4048 | @section @code{.asciz "@var{string}"}@dots{} | |
4049 | ||
4050 | @cindex @code{asciz} directive | |
4051 | @cindex zero-terminated strings | |
4052 | @cindex null-terminated strings | |
4053 | @code{.asciz} is just like @code{.ascii}, but each string is followed by | |
4054 | a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''. | |
4055 | ||
4056 | @node Balign | |
4057 | @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} | |
4058 | ||
4059 | @cindex padding the location counter given number of bytes | |
4060 | @cindex @code{balign} directive | |
4061 | Pad the location counter (in the current subsection) to a particular | |
4062 | storage boundary. The first expression (which must be absolute) is the | |
4063 | alignment request in bytes. For example @samp{.balign 8} advances | |
4064 | the location counter until it is a multiple of 8. If the location counter | |
4065 | is already a multiple of 8, no change is needed. | |
4066 | ||
4067 | The second expression (also absolute) gives the fill value to be stored in the | |
4068 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
4069 | padding bytes are normally zero. However, on some systems, if the section is | |
4070 | marked as containing code and the fill value is omitted, the space is filled | |
4071 | with no-op instructions. | |
4072 | ||
4073 | The third expression is also absolute, and is also optional. If it is present, | |
4074 | it is the maximum number of bytes that should be skipped by this alignment | |
4075 | directive. If doing the alignment would require skipping more bytes than the | |
4076 | specified maximum, then the alignment is not done at all. You can omit the | |
4077 | fill value (the second argument) entirely by simply using two commas after the | |
4078 | required alignment; this can be useful if you want the alignment to be filled | |
4079 | with no-op instructions when appropriate. | |
4080 | ||
4081 | @cindex @code{balignw} directive | |
4082 | @cindex @code{balignl} directive | |
4083 | The @code{.balignw} and @code{.balignl} directives are variants of the | |
4084 | @code{.balign} directive. The @code{.balignw} directive treats the fill | |
4085 | pattern as a two byte word value. The @code{.balignl} directives treats the | |
4086 | fill pattern as a four byte longword value. For example, @code{.balignw | |
4087 | 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be | |
4088 | filled in with the value 0x368d (the exact placement of the bytes depends upon | |
4089 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is | |
4090 | undefined. | |
4091 | ||
4092 | @node Byte | |
4093 | @section @code{.byte @var{expressions}} | |
4094 | ||
4095 | @cindex @code{byte} directive | |
4096 | @cindex integers, one byte | |
4097 | @code{.byte} expects zero or more expressions, separated by commas. | |
4098 | Each expression is assembled into the next byte. | |
4099 | ||
d88ef7a6 TT |
4100 | @node Comm |
4101 | @section @code{.comm @var{symbol} , @var{length} } | |
4102 | ||
4103 | @cindex @code{comm} directive | |
4104 | @cindex symbol, common | |
4105 | @code{.comm} declares a common symbol named @var{symbol}. When linking, a | |
4106 | common symbol in one object file may be merged with a defined or common symbol | |
4107 | of the same name in another object file. If @code{@value{LD}} does not see a | |
4108 | definition for the symbol--just one or more common symbols--then it will | |
4109 | allocate @var{length} bytes of uninitialized memory. @var{length} must be an | |
4110 | absolute expression. If @code{@value{LD}} sees multiple common symbols with | |
4111 | the same name, and they do not all have the same size, it will allocate space | |
4112 | using the largest size. | |
4113 | ||
4114 | @ifset ELF | |
4115 | When using ELF, the @code{.comm} directive takes an optional third argument. | |
4116 | This is the desired alignment of the symbol, specified as a byte boundary (for | |
4117 | example, an alignment of 16 means that the least significant 4 bits of the | |
4118 | address should be zero). The alignment must be an absolute expression, and it | |
4119 | must be a power of two. If @code{@value{LD}} allocates uninitialized memory | |
4120 | for the common symbol, it will use the alignment when placing the symbol. If | |
4121 | no alignment is specified, @command{@value{AS}} will set the alignment to the | |
4122 | largest power of two less than or equal to the size of the symbol, up to a | |
4123 | maximum of 16. | |
4124 | @end ifset | |
4125 | ||
4126 | @ifset HPPA | |
4127 | The syntax for @code{.comm} differs slightly on the HPPA. The syntax is | |
4128 | @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional. | |
4129 | @end ifset | |
4130 | ||
54cfded0 | 4131 | @node CFI directives |
4b7d318b | 4132 | @section @code{.cfi_startproc [simple]} |
54cfded0 AM |
4133 | @cindex @code{cfi_startproc} directive |
4134 | @code{.cfi_startproc} is used at the beginning of each function that | |
4135 | should have an entry in @code{.eh_frame}. It initializes some internal | |
4b7d318b | 4136 | data structures. Don't forget to close the function by |
54cfded0 AM |
4137 | @code{.cfi_endproc}. |
4138 | ||
4b7d318b L |
4139 | Unless @code{.cfi_startproc} is used along with parameter @code{simple} |
4140 | it also emits some architecture dependent initial CFI instructions. | |
4141 | ||
54cfded0 AM |
4142 | @section @code{.cfi_endproc} |
4143 | @cindex @code{cfi_endproc} directive | |
4144 | @code{.cfi_endproc} is used at the end of a function where it closes its | |
4145 | unwind entry previously opened by | |
b45619c0 | 4146 | @code{.cfi_startproc}, and emits it to @code{.eh_frame}. |
54cfded0 | 4147 | |
9b8ae42e JJ |
4148 | @section @code{.cfi_personality @var{encoding} [, @var{exp}]} |
4149 | @code{.cfi_personality} defines personality routine and its encoding. | |
4150 | @var{encoding} must be a constant determining how the personality | |
4151 | should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second | |
4152 | argument is not present, otherwise second argument should be | |
4153 | a constant or a symbol name. When using indirect encodings, | |
4154 | the symbol provided should be the location where personality | |
4155 | can be loaded from, not the personality routine itself. | |
4156 | The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff}, | |
4157 | no personality routine. | |
4158 | ||
4159 | @section @code{.cfi_lsda @var{encoding} [, @var{exp}]} | |
4160 | @code{.cfi_lsda} defines LSDA and its encoding. | |
4161 | @var{encoding} must be a constant determining how the LSDA | |
4162 | should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second | |
4163 | argument is not present, otherwise second argument should be a constant | |
4164 | or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff}, | |
4165 | no LSDA. | |
4166 | ||
54cfded0 AM |
4167 | @section @code{.cfi_def_cfa @var{register}, @var{offset}} |
4168 | @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take | |
4169 | address from @var{register} and add @var{offset} to it}. | |
4170 | ||
4171 | @section @code{.cfi_def_cfa_register @var{register}} | |
4172 | @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From | |
4173 | now on @var{register} will be used instead of the old one. Offset | |
4174 | remains the same. | |
4175 | ||
4176 | @section @code{.cfi_def_cfa_offset @var{offset}} | |
4177 | @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register | |
4178 | remains the same, but @var{offset} is new. Note that it is the | |
4179 | absolute offset that will be added to a defined register to compute | |
4180 | CFA address. | |
4181 | ||
4182 | @section @code{.cfi_adjust_cfa_offset @var{offset}} | |
4183 | Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative | |
4184 | value that is added/substracted from the previous offset. | |
4185 | ||
4186 | @section @code{.cfi_offset @var{register}, @var{offset}} | |
4187 | Previous value of @var{register} is saved at offset @var{offset} from | |
4188 | CFA. | |
4189 | ||
17076204 RH |
4190 | @section @code{.cfi_rel_offset @var{register}, @var{offset}} |
4191 | Previous value of @var{register} is saved at offset @var{offset} from | |
4192 | the current CFA register. This is transformed to @code{.cfi_offset} | |
4193 | using the known displacement of the CFA register from the CFA. | |
4194 | This is often easier to use, because the number will match the | |
4195 | code it's annotating. | |
54cfded0 | 4196 | |
4b7d318b L |
4197 | @section @code{.cfi_register @var{register1}, @var{register2}} |
4198 | Previous value of @var{register1} is saved in register @var{register2}. | |
4199 | ||
4200 | @section @code{.cfi_restore @var{register}} | |
4201 | @code{.cfi_restore} says that the rule for @var{register} is now the | |
4202 | same as it was at the beginning of the function, after all initial | |
4203 | instruction added by @code{.cfi_startproc} were executed. | |
4204 | ||
4205 | @section @code{.cfi_undefined @var{register}} | |
4206 | From now on the previous value of @var{register} can't be restored anymore. | |
4207 | ||
4208 | @section @code{.cfi_same_value @var{register}} | |
4209 | Current value of @var{register} is the same like in the previous frame, | |
4210 | i.e. no restoration needed. | |
4211 | ||
4212 | @section @code{.cfi_remember_state}, | |
4213 | First save all current rules for all registers by @code{.cfi_remember_state}, | |
4214 | then totally screw them up by subsequent @code{.cfi_*} directives and when | |
4215 | everything is hopelessly bad, use @code{.cfi_restore_state} to restore | |
4216 | the previous saved state. | |
4217 | ||
4218 | @section @code{.cfi_return_column @var{register}} | |
4219 | Change return column @var{register}, i.e. the return address is either | |
4220 | directly in @var{register} or can be accessed by rules for @var{register}. | |
4221 | ||
63752a75 JJ |
4222 | @section @code{.cfi_signal_frame} |
4223 | Mark current function as signal trampoline. | |
4224 | ||
6749011b | 4225 | @section @code{.cfi_window_save} |
364b6d8b JJ |
4226 | SPARC register window has been saved. |
4227 | ||
cdfbf930 RH |
4228 | @section @code{.cfi_escape} @var{expression}[, @dots{}] |
4229 | Allows the user to add arbitrary bytes to the unwind info. One | |
4230 | might use this to add OS-specific CFI opcodes, or generic CFI | |
4231 | opcodes that GAS does not yet support. | |
252b5132 | 4232 | |
f1c4cc75 RH |
4233 | @section @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}} |
4234 | The current value of @var{register} is @var{label}. The value of @var{label} | |
4235 | will be encoded in the output file according to @var{encoding}; see the | |
4236 | description of @code{.cfi_personality} for details on this encoding. | |
4237 | ||
4238 | The usefulness of equating a register to a fixed label is probably | |
4239 | limited to the return address register. Here, it can be useful to | |
4240 | mark a code segment that has only one return address which is reached | |
4241 | by a direct branch and no copy of the return address exists in memory | |
4242 | or another register. | |
4243 | ||
bd0eb99b RH |
4244 | @node LNS directives |
4245 | @section @code{.file @var{fileno} @var{filename}} | |
4246 | @cindex @code{file} directive | |
4247 | When emitting dwarf2 line number information @code{.file} assigns filenames | |
4248 | to the @code{.debug_line} file name table. The @var{fileno} operand should | |
4249 | be a unique positive integer to use as the index of the entry in the table. | |
4250 | The @var{filename} operand is a C string literal. | |
4251 | ||
b45619c0 | 4252 | The detail of filename indices is exposed to the user because the filename |
bd0eb99b | 4253 | table is shared with the @code{.debug_info} section of the dwarf2 debugging |
b45619c0 | 4254 | information, and thus the user must know the exact indices that table |
bd0eb99b RH |
4255 | entries will have. |
4256 | ||
ecea7679 | 4257 | @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]} |
bd0eb99b RH |
4258 | @cindex @code{loc} directive |
4259 | The @code{.loc} directive will add row to the @code{.debug_line} line | |
4260 | number matrix corresponding to the immediately following assembly | |
4261 | instruction. The @var{fileno}, @var{lineno}, and optional @var{column} | |
4262 | arguments will be applied to the @code{.debug_line} state machine before | |
4263 | the row is added. | |
4264 | ||
ecea7679 RH |
4265 | The @var{options} are a sequence of the following tokens in any order: |
4266 | ||
4267 | @table @code | |
4268 | @item basic_block | |
4269 | This option will set the @code{basic_block} register in the | |
bd0eb99b RH |
4270 | @code{.debug_line} state machine to @code{true}. |
4271 | ||
ecea7679 RH |
4272 | @item prologue_end |
4273 | This option will set the @code{prologue_end} register in the | |
bd0eb99b RH |
4274 | @code{.debug_line} state machine to @code{true}. |
4275 | ||
ecea7679 RH |
4276 | @item epilogue_begin |
4277 | This option will set the @code{epilogue_begin} register in the | |
bd0eb99b RH |
4278 | @code{.debug_line} state machine to @code{true}. |
4279 | ||
ecea7679 RH |
4280 | @item is_stmt @var{value} |
4281 | This option will set the @code{is_stmt} register in the | |
bd0eb99b RH |
4282 | @code{.debug_line} state machine to @code{value}, which must be |
4283 | either 0 or 1. | |
4284 | ||
ecea7679 | 4285 | @item isa @var{value} |
bd0eb99b RH |
4286 | This directive will set the @code{isa} register in the @code{.debug_line} |
4287 | state machine to @var{value}, which must be an unsigned integer. | |
07a53e5c | 4288 | |
cd1fcb49 NC |
4289 | @end table |
4290 | ||
3a99f02f DJ |
4291 | @section @code{.loc_mark_labels @var{enable}} |
4292 | @cindex @code{loc_mark_labels} directive | |
4293 | The @code{.loc_mark_labels} directive makes the assembler emit an entry | |
07a53e5c RH |
4294 | to the @code{.debug_line} line number matrix with the @code{basic_block} |
4295 | register in the state machine set whenever a code label is seen. | |
4296 | The @var{enable} argument should be either 1 or 0, to enable or disable | |
4297 | this function respectively. | |
4298 | ||
252b5132 RH |
4299 | @node Data |
4300 | @section @code{.data @var{subsection}} | |
4301 | ||
4302 | @cindex @code{data} directive | |
a4fb0134 | 4303 | @code{.data} tells @command{@value{AS}} to assemble the following statements onto the |
252b5132 RH |
4304 | end of the data subsection numbered @var{subsection} (which is an |
4305 | absolute expression). If @var{subsection} is omitted, it defaults | |
4306 | to zero. | |
4307 | ||
4308 | @ifset COFF | |
4309 | @node Def | |
4310 | @section @code{.def @var{name}} | |
4311 | ||
4312 | @cindex @code{def} directive | |
4313 | @cindex COFF symbols, debugging | |
4314 | @cindex debugging COFF symbols | |
4315 | Begin defining debugging information for a symbol @var{name}; the | |
4316 | definition extends until the @code{.endef} directive is encountered. | |
4317 | @ifset BOUT | |
4318 | ||
a4fb0134 | 4319 | This directive is only observed when @command{@value{AS}} is configured for COFF |
252b5132 RH |
4320 | format output; when producing @code{b.out}, @samp{.def} is recognized, |
4321 | but ignored. | |
4322 | @end ifset | |
4323 | @end ifset | |
4324 | ||
4325 | @ifset aout-bout | |
4326 | @node Desc | |
4327 | @section @code{.desc @var{symbol}, @var{abs-expression}} | |
4328 | ||
4329 | @cindex @code{desc} directive | |
4330 | @cindex COFF symbol descriptor | |
4331 | @cindex symbol descriptor, COFF | |
4332 | This directive sets the descriptor of the symbol (@pxref{Symbol Attributes}) | |
4333 | to the low 16 bits of an absolute expression. | |
4334 | ||
4335 | @ifset COFF | |
a4fb0134 | 4336 | The @samp{.desc} directive is not available when @command{@value{AS}} is |
252b5132 | 4337 | configured for COFF output; it is only for @code{a.out} or @code{b.out} |
a4fb0134 | 4338 | object format. For the sake of compatibility, @command{@value{AS}} accepts |
252b5132 RH |
4339 | it, but produces no output, when configured for COFF. |
4340 | @end ifset | |
4341 | @end ifset | |
4342 | ||
4343 | @ifset COFF | |
4344 | @node Dim | |
4345 | @section @code{.dim} | |
4346 | ||
4347 | @cindex @code{dim} directive | |
4348 | @cindex COFF auxiliary symbol information | |
4349 | @cindex auxiliary symbol information, COFF | |
4350 | This directive is generated by compilers to include auxiliary debugging | |
4351 | information in the symbol table. It is only permitted inside | |
4352 | @code{.def}/@code{.endef} pairs. | |
4353 | @ifset BOUT | |
4354 | ||
4355 | @samp{.dim} is only meaningful when generating COFF format output; when | |
a4fb0134 | 4356 | @command{@value{AS}} is generating @code{b.out}, it accepts this directive but |
252b5132 RH |
4357 | ignores it. |
4358 | @end ifset | |
4359 | @end ifset | |
4360 | ||
4361 | @node Double | |
4362 | @section @code{.double @var{flonums}} | |
4363 | ||
4364 | @cindex @code{double} directive | |
4365 | @cindex floating point numbers (double) | |
4366 | @code{.double} expects zero or more flonums, separated by commas. It | |
4367 | assembles floating point numbers. | |
4368 | @ifset GENERIC | |
4369 | The exact kind of floating point numbers emitted depends on how | |
a4fb0134 | 4370 | @command{@value{AS}} is configured. @xref{Machine Dependencies}. |
252b5132 RH |
4371 | @end ifset |
4372 | @ifclear GENERIC | |
4373 | @ifset IEEEFLOAT | |
4374 | On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers | |
4375 | in @sc{ieee} format. | |
4376 | @end ifset | |
4377 | @end ifclear | |
4378 | ||
4379 | @node Eject | |
4380 | @section @code{.eject} | |
4381 | ||
4382 | @cindex @code{eject} directive | |
4383 | @cindex new page, in listings | |
4384 | @cindex page, in listings | |
4385 | @cindex listing control: new page | |
4386 | Force a page break at this point, when generating assembly listings. | |
4387 | ||
4388 | @node Else | |
4389 | @section @code{.else} | |
4390 | ||
4391 | @cindex @code{else} directive | |
a4fb0134 | 4392 | @code{.else} is part of the @command{@value{AS}} support for conditional |
96e9638b | 4393 | assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section |
252b5132 RH |
4394 | of code to be assembled if the condition for the preceding @code{.if} |
4395 | was false. | |
4396 | ||
3fd9f047 TW |
4397 | @node Elseif |
4398 | @section @code{.elseif} | |
4399 | ||
4400 | @cindex @code{elseif} directive | |
a4fb0134 | 4401 | @code{.elseif} is part of the @command{@value{AS}} support for conditional |
96e9638b | 4402 | assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new |
3fd9f047 TW |
4403 | @code{.if} block that would otherwise fill the entire @code{.else} section. |
4404 | ||
252b5132 RH |
4405 | @node End |
4406 | @section @code{.end} | |
4407 | ||
4408 | @cindex @code{end} directive | |
a4fb0134 | 4409 | @code{.end} marks the end of the assembly file. @command{@value{AS}} does not |
252b5132 RH |
4410 | process anything in the file past the @code{.end} directive. |
4411 | ||
4412 | @ifset COFF | |
4413 | @node Endef | |
4414 | @section @code{.endef} | |
4415 | ||
4416 | @cindex @code{endef} directive | |
4417 | This directive flags the end of a symbol definition begun with | |
4418 | @code{.def}. | |
4419 | @ifset BOUT | |
4420 | ||
4421 | @samp{.endef} is only meaningful when generating COFF format output; if | |
a4fb0134 | 4422 | @command{@value{AS}} is configured to generate @code{b.out}, it accepts this |
252b5132 RH |
4423 | directive but ignores it. |
4424 | @end ifset | |
4425 | @end ifset | |
4426 | ||
4427 | @node Endfunc | |
4428 | @section @code{.endfunc} | |
4429 | @cindex @code{endfunc} directive | |
4430 | @code{.endfunc} marks the end of a function specified with @code{.func}. | |
4431 | ||
4432 | @node Endif | |
4433 | @section @code{.endif} | |
4434 | ||
4435 | @cindex @code{endif} directive | |
a4fb0134 | 4436 | @code{.endif} is part of the @command{@value{AS}} support for conditional assembly; |
252b5132 RH |
4437 | it marks the end of a block of code that is only assembled |
4438 | conditionally. @xref{If,,@code{.if}}. | |
4439 | ||
4440 | @node Equ | |
4441 | @section @code{.equ @var{symbol}, @var{expression}} | |
4442 | ||
4443 | @cindex @code{equ} directive | |
4444 | @cindex assigning values to symbols | |
4445 | @cindex symbols, assigning values to | |
4446 | This directive sets the value of @var{symbol} to @var{expression}. | |
96e9638b | 4447 | It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}. |
252b5132 RH |
4448 | |
4449 | @ifset HPPA | |
4450 | The syntax for @code{equ} on the HPPA is | |
4451 | @samp{@var{symbol} .equ @var{expression}}. | |
4452 | @end ifset | |
4453 | ||
3c9b82ba NC |
4454 | @ifset Z80 |
4455 | The syntax for @code{equ} on the Z80 is | |
4456 | @samp{@var{symbol} equ @var{expression}}. | |
4457 | On the Z80 it is an eror if @var{symbol} is already defined, | |
96e9638b BW |
4458 | but the symbol is not protected from later redefinition. |
4459 | Compare @ref{Equiv}. | |
3c9b82ba NC |
4460 | @end ifset |
4461 | ||
252b5132 RH |
4462 | @node Equiv |
4463 | @section @code{.equiv @var{symbol}, @var{expression}} | |
4464 | @cindex @code{equiv} directive | |
4465 | The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that | |
8dfa0188 NC |
4466 | the assembler will signal an error if @var{symbol} is already defined. Note a |
4467 | symbol which has been referenced but not actually defined is considered to be | |
4468 | undefined. | |
252b5132 RH |
4469 | |
4470 | Except for the contents of the error message, this is roughly equivalent to | |
4471 | @smallexample | |
4472 | .ifdef SYM | |
4473 | .err | |
4474 | .endif | |
4475 | .equ SYM,VAL | |
4476 | @end smallexample | |
9497f5ac NC |
4477 | plus it protects the symbol from later redefinition. |
4478 | ||
4479 | @node Eqv | |
4480 | @section @code{.eqv @var{symbol}, @var{expression}} | |
4481 | @cindex @code{eqv} directive | |
4482 | The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to | |
4483 | evaluate the expression or any part of it immediately. Instead each time | |
4484 | the resulting symbol is used in an expression, a snapshot of its current | |
4485 | value is taken. | |
252b5132 RH |
4486 | |
4487 | @node Err | |
4488 | @section @code{.err} | |
4489 | @cindex @code{err} directive | |
a4fb0134 SC |
4490 | If @command{@value{AS}} assembles a @code{.err} directive, it will print an error |
4491 | message and, unless the @option{-Z} option was used, it will not generate an | |
f9eb6721 | 4492 | object file. This can be used to signal an error in conditionally compiled code. |
252b5132 | 4493 | |
d190d046 HPN |
4494 | @node Error |
4495 | @section @code{.error "@var{string}"} | |
4496 | @cindex error directive | |
4497 | ||
4498 | Similarly to @code{.err}, this directive emits an error, but you can specify a | |
4499 | string that will be emitted as the error message. If you don't specify the | |
4500 | message, it defaults to @code{".error directive invoked in source file"}. | |
4501 | @xref{Errors, ,Error and Warning Messages}. | |
4502 | ||
4503 | @smallexample | |
4504 | .error "This code has not been assembled and tested." | |
4505 | @end smallexample | |
4506 | ||
252b5132 RH |
4507 | @node Exitm |
4508 | @section @code{.exitm} | |
4509 | Exit early from the current macro definition. @xref{Macro}. | |
4510 | ||
4511 | @node Extern | |
4512 | @section @code{.extern} | |
4513 | ||
4514 | @cindex @code{extern} directive | |
4515 | @code{.extern} is accepted in the source program---for compatibility | |
a4fb0134 | 4516 | with other assemblers---but it is ignored. @command{@value{AS}} treats |
252b5132 RH |
4517 | all undefined symbols as external. |
4518 | ||
4519 | @node Fail | |
4520 | @section @code{.fail @var{expression}} | |
4521 | ||
4522 | @cindex @code{fail} directive | |
4523 | Generates an error or a warning. If the value of the @var{expression} is 500 | |
a4fb0134 SC |
4524 | or more, @command{@value{AS}} will print a warning message. If the value is less |
4525 | than 500, @command{@value{AS}} will print an error message. The message will | |
252b5132 RH |
4526 | include the value of @var{expression}. This can occasionally be useful inside |
4527 | complex nested macros or conditional assembly. | |
4528 | ||
4529 | @ifclear no-file-dir | |
4530 | @node File | |
4531 | @section @code{.file @var{string}} | |
4532 | ||
4533 | @cindex @code{file} directive | |
4534 | @cindex logical file name | |
4535 | @cindex file name, logical | |
a4fb0134 | 4536 | @code{.file} tells @command{@value{AS}} that we are about to start a new logical |
252b5132 RH |
4537 | file. @var{string} is the new file name. In general, the filename is |
4538 | recognized whether or not it is surrounded by quotes @samp{"}; but if you wish | |
4539 | to specify an empty file name, you must give the quotes--@code{""}. This | |
4540 | statement may go away in future: it is only recognized to be compatible with | |
a4fb0134 | 4541 | old @command{@value{AS}} programs. |
252b5132 RH |
4542 | @end ifclear |
4543 | ||
4544 | @node Fill | |
4545 | @section @code{.fill @var{repeat} , @var{size} , @var{value}} | |
4546 | ||
4547 | @cindex @code{fill} directive | |
4548 | @cindex writing patterns in memory | |
4549 | @cindex patterns, writing in memory | |
bc64be0c | 4550 | @var{repeat}, @var{size} and @var{value} are absolute expressions. |
252b5132 RH |
4551 | This emits @var{repeat} copies of @var{size} bytes. @var{Repeat} |
4552 | may be zero or more. @var{Size} may be zero or more, but if it is | |
4553 | more than 8, then it is deemed to have the value 8, compatible with | |
4554 | other people's assemblers. The contents of each @var{repeat} bytes | |
4555 | is taken from an 8-byte number. The highest order 4 bytes are | |
4556 | zero. The lowest order 4 bytes are @var{value} rendered in the | |
a4fb0134 | 4557 | byte-order of an integer on the computer @command{@value{AS}} is assembling for. |
252b5132 RH |
4558 | Each @var{size} bytes in a repetition is taken from the lowest order |
4559 | @var{size} bytes of this number. Again, this bizarre behavior is | |
4560 | compatible with other people's assemblers. | |
4561 | ||
4562 | @var{size} and @var{value} are optional. | |
4563 | If the second comma and @var{value} are absent, @var{value} is | |
4564 | assumed zero. If the first comma and following tokens are absent, | |
4565 | @var{size} is assumed to be 1. | |
4566 | ||
4567 | @node Float | |
4568 | @section @code{.float @var{flonums}} | |
4569 | ||
4570 | @cindex floating point numbers (single) | |
4571 | @cindex @code{float} directive | |
4572 | This directive assembles zero or more flonums, separated by commas. It | |
4573 | has the same effect as @code{.single}. | |
4574 | @ifset GENERIC | |
4575 | The exact kind of floating point numbers emitted depends on how | |
a4fb0134 | 4576 | @command{@value{AS}} is configured. |
252b5132 RH |
4577 | @xref{Machine Dependencies}. |
4578 | @end ifset | |
4579 | @ifclear GENERIC | |
4580 | @ifset IEEEFLOAT | |
4581 | On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers | |
4582 | in @sc{ieee} format. | |
4583 | @end ifset | |
4584 | @end ifclear | |
4585 | ||
4586 | @node Func | |
4587 | @section @code{.func @var{name}[,@var{label}]} | |
4588 | @cindex @code{func} directive | |
4589 | @code{.func} emits debugging information to denote function @var{name}, and | |
4590 | is ignored unless the file is assembled with debugging enabled. | |
05da4302 | 4591 | Only @samp{--gstabs[+]} is currently supported. |
252b5132 RH |
4592 | @var{label} is the entry point of the function and if omitted @var{name} |
4593 | prepended with the @samp{leading char} is used. | |
4594 | @samp{leading char} is usually @code{_} or nothing, depending on the target. | |
4595 | All functions are currently defined to have @code{void} return type. | |
4596 | The function must be terminated with @code{.endfunc}. | |
4597 | ||
4598 | @node Global | |
4599 | @section @code{.global @var{symbol}}, @code{.globl @var{symbol}} | |
4600 | ||
4601 | @cindex @code{global} directive | |
4602 | @cindex symbol, making visible to linker | |
4603 | @code{.global} makes the symbol visible to @code{@value{LD}}. If you define | |
4604 | @var{symbol} in your partial program, its value is made available to | |
4605 | other partial programs that are linked with it. Otherwise, | |
4606 | @var{symbol} takes its attributes from a symbol of the same name | |
4607 | from another file linked into the same program. | |
4608 | ||
4609 | Both spellings (@samp{.globl} and @samp{.global}) are accepted, for | |
4610 | compatibility with other assemblers. | |
4611 | ||
4612 | @ifset HPPA | |
4613 | On the HPPA, @code{.global} is not always enough to make it accessible to other | |
4614 | partial programs. You may need the HPPA-only @code{.EXPORT} directive as well. | |
96e9638b | 4615 | @xref{HPPA Directives, ,HPPA Assembler Directives}. |
252b5132 RH |
4616 | @end ifset |
4617 | ||
c91d2e08 | 4618 | @ifset ELF |
3a99f02f DJ |
4619 | @node Gnu_attribute |
4620 | @section @code{.gnu_attribute @var{tag},@var{value}} | |
4621 | Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}. | |
4622 | ||
c91d2e08 NC |
4623 | @node Hidden |
4624 | @section @code{.hidden @var{names}} | |
4625 | ||
c1253627 NC |
4626 | @cindex @code{hidden} directive |
4627 | @cindex visibility | |
ed9589d4 | 4628 | This is one of the ELF visibility directives. The other two are |
a349d9dd PB |
4629 | @code{.internal} (@pxref{Internal,,@code{.internal}}) and |
4630 | @code{.protected} (@pxref{Protected,,@code{.protected}}). | |
c91d2e08 NC |
4631 | |
4632 | This directive overrides the named symbols default visibility (which is set by | |
4633 | their binding: local, global or weak). The directive sets the visibility to | |
4634 | @code{hidden} which means that the symbols are not visible to other components. | |
4635 | Such symbols are always considered to be @code{protected} as well. | |
4636 | @end ifset | |
4637 | ||
252b5132 RH |
4638 | @node hword |
4639 | @section @code{.hword @var{expressions}} | |
4640 | ||
4641 | @cindex @code{hword} directive | |
4642 | @cindex integers, 16-bit | |
4643 | @cindex numbers, 16-bit | |
4644 | @cindex sixteen bit integers | |
4645 | This expects zero or more @var{expressions}, and emits | |
4646 | a 16 bit number for each. | |
4647 | ||
4648 | @ifset GENERIC | |
4649 | This directive is a synonym for @samp{.short}; depending on the target | |
4650 | architecture, it may also be a synonym for @samp{.word}. | |
4651 | @end ifset | |
4652 | @ifclear GENERIC | |
4653 | @ifset W32 | |
4654 | This directive is a synonym for @samp{.short}. | |
4655 | @end ifset | |
4656 | @ifset W16 | |
4657 | This directive is a synonym for both @samp{.short} and @samp{.word}. | |
4658 | @end ifset | |
4659 | @end ifclear | |
4660 | ||
4661 | @node Ident | |
4662 | @section @code{.ident} | |
4663 | ||
4664 | @cindex @code{ident} directive | |
cb4c78d6 BE |
4665 | |
4666 | This directive is used by some assemblers to place tags in object files. The | |
4667 | behavior of this directive varies depending on the target. When using the | |
4668 | a.out object file format, @command{@value{AS}} simply accepts the directive for | |
4669 | source-file compatibility with existing assemblers, but does not emit anything | |
4670 | for it. When using COFF, comments are emitted to the @code{.comment} or | |
4671 | @code{.rdata} section, depending on the target. When using ELF, comments are | |
4672 | emitted to the @code{.comment} section. | |
252b5132 RH |
4673 | |
4674 | @node If | |
4675 | @section @code{.if @var{absolute expression}} | |
4676 | ||
4677 | @cindex conditional assembly | |
4678 | @cindex @code{if} directive | |
4679 | @code{.if} marks the beginning of a section of code which is only | |
4680 | considered part of the source program being assembled if the argument | |
4681 | (which must be an @var{absolute expression}) is non-zero. The end of | |
4682 | the conditional section of code must be marked by @code{.endif} | |
4683 | (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the | |
4684 | alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}). | |
3fd9f047 TW |
4685 | If you have several conditions to check, @code{.elseif} may be used to avoid |
4686 | nesting blocks if/else within each subsequent @code{.else} block. | |
252b5132 RH |
4687 | |
4688 | The following variants of @code{.if} are also supported: | |
4689 | @table @code | |
4690 | @cindex @code{ifdef} directive | |
4691 | @item .ifdef @var{symbol} | |
4692 | Assembles the following section of code if the specified @var{symbol} | |
8dfa0188 NC |
4693 | has been defined. Note a symbol which has been referenced but not yet defined |
4694 | is considered to be undefined. | |
252b5132 | 4695 | |
26aca5f6 JB |
4696 | @cindex @code{ifb} directive |
4697 | @item .ifb @var{text} | |
4698 | Assembles the following section of code if the operand is blank (empty). | |
4699 | ||
252b5132 RH |
4700 | @cindex @code{ifc} directive |
4701 | @item .ifc @var{string1},@var{string2} | |
4702 | Assembles the following section of code if the two strings are the same. The | |
4703 | strings may be optionally quoted with single quotes. If they are not quoted, | |
4704 | the first string stops at the first comma, and the second string stops at the | |
4705 | end of the line. Strings which contain whitespace should be quoted. The | |
4706 | string comparison is case sensitive. | |
4707 | ||
4708 | @cindex @code{ifeq} directive | |
4709 | @item .ifeq @var{absolute expression} | |
4710 | Assembles the following section of code if the argument is zero. | |
4711 | ||
4712 | @cindex @code{ifeqs} directive | |
4713 | @item .ifeqs @var{string1},@var{string2} | |
4714 | Another form of @code{.ifc}. The strings must be quoted using double quotes. | |
4715 | ||
4716 | @cindex @code{ifge} directive | |
4717 | @item .ifge @var{absolute expression} | |
4718 | Assembles the following section of code if the argument is greater than or | |
4719 | equal to zero. | |
4720 | ||
4721 | @cindex @code{ifgt} directive | |
4722 | @item .ifgt @var{absolute expression} | |
4723 | Assembles the following section of code if the argument is greater than zero. | |
4724 | ||
4725 | @cindex @code{ifle} directive | |
4726 | @item .ifle @var{absolute expression} | |
4727 | Assembles the following section of code if the argument is less than or equal | |
4728 | to zero. | |
4729 | ||
4730 | @cindex @code{iflt} directive | |
4731 | @item .iflt @var{absolute expression} | |
4732 | Assembles the following section of code if the argument is less than zero. | |
4733 | ||
26aca5f6 JB |
4734 | @cindex @code{ifnb} directive |
4735 | @item .ifnb @var{text} | |
4736 | Like @code{.ifb}, but the sense of the test is reversed: this assembles the | |
4737 | following section of code if the operand is non-blank (non-empty). | |
4738 | ||
252b5132 RH |
4739 | @cindex @code{ifnc} directive |
4740 | @item .ifnc @var{string1},@var{string2}. | |
4741 | Like @code{.ifc}, but the sense of the test is reversed: this assembles the | |
4742 | following section of code if the two strings are not the same. | |
4743 | ||
4744 | @cindex @code{ifndef} directive | |
4745 | @cindex @code{ifnotdef} directive | |
4746 | @item .ifndef @var{symbol} | |
4747 | @itemx .ifnotdef @var{symbol} | |
4748 | Assembles the following section of code if the specified @var{symbol} | |
8dfa0188 NC |
4749 | has not been defined. Both spelling variants are equivalent. Note a symbol |
4750 | which has been referenced but not yet defined is considered to be undefined. | |
252b5132 RH |
4751 | |
4752 | @cindex @code{ifne} directive | |
4753 | @item .ifne @var{absolute expression} | |
4754 | Assembles the following section of code if the argument is not equal to zero | |
4755 | (in other words, this is equivalent to @code{.if}). | |
4756 | ||
4757 | @cindex @code{ifnes} directive | |
4758 | @item .ifnes @var{string1},@var{string2} | |
4759 | Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the | |
4760 | following section of code if the two strings are not the same. | |
4761 | @end table | |
4762 | ||
7e005732 NC |
4763 | @node Incbin |
4764 | @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]} | |
4765 | ||
4766 | @cindex @code{incbin} directive | |
4767 | @cindex binary files, including | |
4768 | The @code{incbin} directive includes @var{file} verbatim at the current | |
4769 | location. You can control the search paths used with the @samp{-I} command-line | |
4770 | option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required | |
4771 | around @var{file}. | |
4772 | ||
4773 | The @var{skip} argument skips a number of bytes from the start of the | |
4774 | @var{file}. The @var{count} argument indicates the maximum number of bytes to | |
15dcfbc3 NC |
4775 | read. Note that the data is not aligned in any way, so it is the user's |
4776 | responsibility to make sure that proper alignment is provided both before and | |
4777 | after the @code{incbin} directive. | |
7e005732 | 4778 | |
252b5132 RH |
4779 | @node Include |
4780 | @section @code{.include "@var{file}"} | |
4781 | ||
4782 | @cindex @code{include} directive | |
4783 | @cindex supporting files, including | |
4784 | @cindex files, including | |
4785 | This directive provides a way to include supporting files at specified | |
4786 | points in your source program. The code from @var{file} is assembled as | |
4787 | if it followed the point of the @code{.include}; when the end of the | |
4788 | included file is reached, assembly of the original file continues. You | |
4789 | can control the search paths used with the @samp{-I} command-line option | |
4790 | (@pxref{Invoking,,Command-Line Options}). Quotation marks are required | |
4791 | around @var{file}. | |
4792 | ||
4793 | @node Int | |
4794 | @section @code{.int @var{expressions}} | |
4795 | ||
4796 | @cindex @code{int} directive | |
4797 | @cindex integers, 32-bit | |
4798 | Expect zero or more @var{expressions}, of any section, separated by commas. | |
4799 | For each expression, emit a number that, at run time, is the value of that | |
4800 | expression. The byte order and bit size of the number depends on what kind | |
4801 | of target the assembly is for. | |
4802 | ||
4803 | @ifclear GENERIC | |
4804 | @ifset H8 | |
7be1c489 | 4805 | On most forms of the H8/300, @code{.int} emits 16-bit |
c2dcd04e | 4806 | integers. On the H8/300H and the Renesas SH, however, @code{.int} emits |
252b5132 RH |
4807 | 32-bit integers. |
4808 | @end ifset | |
4809 | @end ifclear | |
4810 | ||
c91d2e08 NC |
4811 | @ifset ELF |
4812 | @node Internal | |
4813 | @section @code{.internal @var{names}} | |
4814 | ||
c1253627 NC |
4815 | @cindex @code{internal} directive |
4816 | @cindex visibility | |
ed9589d4 | 4817 | This is one of the ELF visibility directives. The other two are |
a349d9dd PB |
4818 | @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and |
4819 | @code{.protected} (@pxref{Protected,,@code{.protected}}). | |
c91d2e08 NC |
4820 | |
4821 | This directive overrides the named symbols default visibility (which is set by | |
4822 | their binding: local, global or weak). The directive sets the visibility to | |
4823 | @code{internal} which means that the symbols are considered to be @code{hidden} | |
c1253627 | 4824 | (i.e., not visible to other components), and that some extra, processor specific |
c91d2e08 NC |
4825 | processing must also be performed upon the symbols as well. |
4826 | @end ifset | |
4827 | ||
252b5132 RH |
4828 | @node Irp |
4829 | @section @code{.irp @var{symbol},@var{values}}@dots{} | |
4830 | ||
4831 | @cindex @code{irp} directive | |
4832 | Evaluate a sequence of statements assigning different values to @var{symbol}. | |
4833 | The sequence of statements starts at the @code{.irp} directive, and is | |
4834 | terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is | |
4835 | set to @var{value}, and the sequence of statements is assembled. If no | |
4836 | @var{value} is listed, the sequence of statements is assembled once, with | |
4837 | @var{symbol} set to the null string. To refer to @var{symbol} within the | |
4838 | sequence of statements, use @var{\symbol}. | |
4839 | ||
4840 | For example, assembling | |
4841 | ||
4842 | @example | |
4843 | .irp param,1,2,3 | |
4844 | move d\param,sp@@- | |
4845 | .endr | |
4846 | @end example | |
4847 | ||
4848 | is equivalent to assembling | |
4849 | ||
4850 | @example | |
4851 | move d1,sp@@- | |
4852 | move d2,sp@@- | |
4853 | move d3,sp@@- | |
4854 | @end example | |
4855 | ||
96e9638b | 4856 | For some caveats with the spelling of @var{symbol}, see also @ref{Macro}. |
5e75c3ab | 4857 | |
252b5132 RH |
4858 | @node Irpc |
4859 | @section @code{.irpc @var{symbol},@var{values}}@dots{} | |
4860 | ||
4861 | @cindex @code{irpc} directive | |
4862 | Evaluate a sequence of statements assigning different values to @var{symbol}. | |
4863 | The sequence of statements starts at the @code{.irpc} directive, and is | |
4864 | terminated by an @code{.endr} directive. For each character in @var{value}, | |
4865 | @var{symbol} is set to the character, and the sequence of statements is | |
4866 | assembled. If no @var{value} is listed, the sequence of statements is | |
4867 | assembled once, with @var{symbol} set to the null string. To refer to | |
4868 | @var{symbol} within the sequence of statements, use @var{\symbol}. | |
4869 | ||
4870 | For example, assembling | |
4871 | ||
4872 | @example | |
4873 | .irpc param,123 | |
4874 | move d\param,sp@@- | |
4875 | .endr | |
4876 | @end example | |
4877 | ||
4878 | is equivalent to assembling | |
4879 | ||
4880 | @example | |
4881 | move d1,sp@@- | |
4882 | move d2,sp@@- | |
4883 | move d3,sp@@- | |
4884 | @end example | |
4885 | ||
5e75c3ab JB |
4886 | For some caveats with the spelling of @var{symbol}, see also the discussion |
4887 | at @xref{Macro}. | |
4888 | ||
252b5132 RH |
4889 | @node Lcomm |
4890 | @section @code{.lcomm @var{symbol} , @var{length}} | |
4891 | ||
4892 | @cindex @code{lcomm} directive | |
4893 | @cindex local common symbols | |
4894 | @cindex symbols, local common | |
4895 | Reserve @var{length} (an absolute expression) bytes for a local common | |
4896 | denoted by @var{symbol}. The section and value of @var{symbol} are | |
4897 | those of the new local common. The addresses are allocated in the bss | |
4898 | section, so that at run-time the bytes start off zeroed. @var{Symbol} | |
4899 | is not declared global (@pxref{Global,,@code{.global}}), so is normally | |
4900 | not visible to @code{@value{LD}}. | |
4901 | ||
4902 | @ifset GENERIC | |
4903 | Some targets permit a third argument to be used with @code{.lcomm}. This | |
4904 | argument specifies the desired alignment of the symbol in the bss section. | |
4905 | @end ifset | |
4906 | ||
4907 | @ifset HPPA | |
4908 | The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is | |
4909 | @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional. | |
4910 | @end ifset | |
4911 | ||
4912 | @node Lflags | |
4913 | @section @code{.lflags} | |
4914 | ||
4915 | @cindex @code{lflags} directive (ignored) | |
a4fb0134 | 4916 | @command{@value{AS}} accepts this directive, for compatibility with other |
252b5132 RH |
4917 | assemblers, but ignores it. |
4918 | ||
4919 | @ifclear no-line-dir | |
4920 | @node Line | |
4921 | @section @code{.line @var{line-number}} | |
4922 | ||
4923 | @cindex @code{line} directive | |
4924 | @end ifclear | |
4925 | @ifset no-line-dir | |
4926 | @node Ln | |
4927 | @section @code{.ln @var{line-number}} | |
4928 | ||
4929 | @cindex @code{ln} directive | |
4930 | @end ifset | |
4931 | @cindex logical line number | |
4932 | @ifset aout-bout | |
4933 | Change the logical line number. @var{line-number} must be an absolute | |
4934 | expression. The next line has that logical line number. Therefore any other | |
4935 | statements on the current line (after a statement separator character) are | |
4936 | reported as on logical line number @var{line-number} @minus{} 1. One day | |
a4fb0134 | 4937 | @command{@value{AS}} will no longer support this directive: it is recognized only |
252b5132 RH |
4938 | for compatibility with existing assembler programs. |
4939 | ||
252b5132 RH |
4940 | @end ifset |
4941 | ||
4942 | @ifclear no-line-dir | |
4943 | Even though this is a directive associated with the @code{a.out} or | |
a4fb0134 | 4944 | @code{b.out} object-code formats, @command{@value{AS}} still recognizes it |
252b5132 RH |
4945 | when producing COFF output, and treats @samp{.line} as though it |
4946 | were the COFF @samp{.ln} @emph{if} it is found outside a | |
4947 | @code{.def}/@code{.endef} pair. | |
4948 | ||
4949 | Inside a @code{.def}, @samp{.line} is, instead, one of the directives | |
4950 | used by compilers to generate auxiliary symbol information for | |
4951 | debugging. | |
4952 | @end ifclear | |
4953 | ||
4954 | @node Linkonce | |
4955 | @section @code{.linkonce [@var{type}]} | |
4956 | @cindex COMDAT | |
4957 | @cindex @code{linkonce} directive | |
4958 | @cindex common sections | |
4959 | Mark the current section so that the linker only includes a single copy of it. | |
4960 | This may be used to include the same section in several different object files, | |
4961 | but ensure that the linker will only include it once in the final output file. | |
4962 | The @code{.linkonce} pseudo-op must be used for each instance of the section. | |
4963 | Duplicate sections are detected based on the section name, so it should be | |
4964 | unique. | |
4965 | ||
4966 | This directive is only supported by a few object file formats; as of this | |
4967 | writing, the only object file format which supports it is the Portable | |
4968 | Executable format used on Windows NT. | |
4969 | ||
4970 | The @var{type} argument is optional. If specified, it must be one of the | |
4971 | following strings. For example: | |
4972 | @smallexample | |
4973 | .linkonce same_size | |
4974 | @end smallexample | |
4975 | Not all types may be supported on all object file formats. | |
4976 | ||
4977 | @table @code | |
4978 | @item discard | |
4979 | Silently discard duplicate sections. This is the default. | |
4980 | ||
4981 | @item one_only | |
4982 | Warn if there are duplicate sections, but still keep only one copy. | |
4983 | ||
4984 | @item same_size | |
4985 | Warn if any of the duplicates have different sizes. | |
4986 | ||
4987 | @item same_contents | |
4988 | Warn if any of the duplicates do not have exactly the same contents. | |
4989 | @end table | |
4990 | ||
4991 | @node Ln | |
4992 | @section @code{.ln @var{line-number}} | |
4993 | ||
4994 | @cindex @code{ln} directive | |
4995 | @ifclear no-line-dir | |
4996 | @samp{.ln} is a synonym for @samp{.line}. | |
4997 | @end ifclear | |
4998 | @ifset no-line-dir | |
a4fb0134 | 4999 | Tell @command{@value{AS}} to change the logical line number. @var{line-number} |
252b5132 RH |
5000 | must be an absolute expression. The next line has that logical |
5001 | line number, so any other statements on the current line (after a | |
5002 | statement separator character @code{;}) are reported as on logical | |
5003 | line number @var{line-number} @minus{} 1. | |
5004 | @ifset BOUT | |
5005 | ||
a4fb0134 | 5006 | This directive is accepted, but ignored, when @command{@value{AS}} is |
252b5132 RH |
5007 | configured for @code{b.out}; its effect is only associated with COFF |
5008 | output format. | |
5009 | @end ifset | |
5010 | @end ifset | |
5011 | ||
5012 | @node MRI | |
5013 | @section @code{.mri @var{val}} | |
5014 | ||
5015 | @cindex @code{mri} directive | |
5016 | @cindex MRI mode, temporarily | |
a4fb0134 SC |
5017 | If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If |
5018 | @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change | |
252b5132 RH |
5019 | affects code assembled until the next @code{.mri} directive, or until the end |
5020 | of the file. @xref{M, MRI mode, MRI mode}. | |
5021 | ||
5022 | @node List | |
5023 | @section @code{.list} | |
5024 | ||
5025 | @cindex @code{list} directive | |
5026 | @cindex listing control, turning on | |
5027 | Control (in conjunction with the @code{.nolist} directive) whether or | |
5028 | not assembly listings are generated. These two directives maintain an | |
5029 | internal counter (which is zero initially). @code{.list} increments the | |
5030 | counter, and @code{.nolist} decrements it. Assembly listings are | |
5031 | generated whenever the counter is greater than zero. | |
5032 | ||
5033 | By default, listings are disabled. When you enable them (with the | |
5034 | @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}), | |
5035 | the initial value of the listing counter is one. | |
5036 | ||
5037 | @node Long | |
5038 | @section @code{.long @var{expressions}} | |
5039 | ||
5040 | @cindex @code{long} directive | |
96e9638b | 5041 | @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}. |
252b5132 RH |
5042 | |
5043 | @ignore | |
5044 | @c no one seems to know what this is for or whether this description is | |
5045 | @c what it really ought to do | |
5046 | @node Lsym | |
5047 | @section @code{.lsym @var{symbol}, @var{expression}} | |
5048 | ||
5049 | @cindex @code{lsym} directive | |
5050 | @cindex symbol, not referenced in assembly | |
5051 | @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in | |
5052 | the hash table, ensuring it cannot be referenced by name during the | |
5053 | rest of the assembly. This sets the attributes of the symbol to be | |
5054 | the same as the expression value: | |
5055 | @smallexample | |
5056 | @var{other} = @var{descriptor} = 0 | |
5057 | @var{type} = @r{(section of @var{expression})} | |
5058 | @var{value} = @var{expression} | |
5059 | @end smallexample | |
5060 | @noindent | |
5061 | The new symbol is not flagged as external. | |
5062 | @end ignore | |
5063 | ||
5064 | @node Macro | |
5065 | @section @code{.macro} | |
5066 | ||
5067 | @cindex macros | |
5068 | The commands @code{.macro} and @code{.endm} allow you to define macros that | |
5069 | generate assembly output. For example, this definition specifies a macro | |
5070 | @code{sum} that puts a sequence of numbers into memory: | |
5071 | ||
5072 | @example | |
5073 | .macro sum from=0, to=5 | |
5074 | .long \from | |
5075 | .if \to-\from | |
5076 | sum "(\from+1)",\to | |
5077 | .endif | |
5078 | .endm | |
5079 | @end example | |
5080 | ||
5081 | @noindent | |
5082 | With that definition, @samp{SUM 0,5} is equivalent to this assembly input: | |
5083 | ||
5084 | @example | |
5085 | .long 0 | |
5086 | .long 1 | |
5087 | .long 2 | |
5088 | .long 3 | |
5089 | .long 4 | |
5090 | .long 5 | |
5091 | @end example | |
5092 | ||
5093 | @ftable @code | |
5094 | @item .macro @var{macname} | |
5095 | @itemx .macro @var{macname} @var{macargs} @dots{} | |
5096 | @cindex @code{macro} directive | |
5097 | Begin the definition of a macro called @var{macname}. If your macro | |
5098 | definition requires arguments, specify their names after the macro name, | |
6eaeac8a JB |
5099 | separated by commas or spaces. You can qualify the macro argument to |
5100 | indicate whether all invocations must specify a non-blank value (through | |
5101 | @samp{:@code{req}}), or whether it takes all of the remaining arguments | |
5102 | (through @samp{:@code{vararg}}). You can supply a default value for any | |
fffeaa5f JB |
5103 | macro argument by following the name with @samp{=@var{deflt}}. You |
5104 | cannot define two macros with the same @var{macname} unless it has been | |
96e9638b | 5105 | subject to the @code{.purgem} directive (@pxref{Purgem}) between the two |
fffeaa5f | 5106 | definitions. For example, these are all valid @code{.macro} statements: |
252b5132 RH |
5107 | |
5108 | @table @code | |
5109 | @item .macro comm | |
5110 | Begin the definition of a macro called @code{comm}, which takes no | |
5111 | arguments. | |
5112 | ||
6258339f | 5113 | @item .macro plus1 p, p1 |
252b5132 RH |
5114 | @itemx .macro plus1 p p1 |
5115 | Either statement begins the definition of a macro called @code{plus1}, | |
5116 | which takes two arguments; within the macro definition, write | |
5117 | @samp{\p} or @samp{\p1} to evaluate the arguments. | |
5118 | ||
5119 | @item .macro reserve_str p1=0 p2 | |
5120 | Begin the definition of a macro called @code{reserve_str}, with two | |
5121 | arguments. The first argument has a default value, but not the second. | |
5122 | After the definition is complete, you can call the macro either as | |
5123 | @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to | |
5124 | @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str | |
5125 | ,@var{b}} (with @samp{\p1} evaluating as the default, in this case | |
5126 | @samp{0}, and @samp{\p2} evaluating to @var{b}). | |
252b5132 | 5127 | |
6eaeac8a JB |
5128 | @item .macro m p1:req, p2=0, p3:vararg |
5129 | Begin the definition of a macro called @code{m}, with at least three | |
5130 | arguments. The first argument must always have a value specified, but | |
5131 | not the second, which instead has a default value. The third formal | |
5132 | will get assigned all remaining arguments specified at invocation time. | |
5133 | ||
252b5132 RH |
5134 | When you call a macro, you can specify the argument values either by |
5135 | position, or by keyword. For example, @samp{sum 9,17} is equivalent to | |
5136 | @samp{sum to=17, from=9}. | |
5137 | ||
6258339f NC |
5138 | @end table |
5139 | ||
5e75c3ab JB |
5140 | Note that since each of the @var{macargs} can be an identifier exactly |
5141 | as any other one permitted by the target architecture, there may be | |
5142 | occasional problems if the target hand-crafts special meanings to certain | |
6258339f | 5143 | characters when they occur in a special position. For example, if the colon |
5e75c3ab | 5144 | (@code{:}) is generally permitted to be part of a symbol name, but the |
6258339f | 5145 | architecture specific code special-cases it when occurring as the final |
5e75c3ab JB |
5146 | character of a symbol (to denote a label), then the macro parameter |
5147 | replacement code will have no way of knowing that and consider the whole | |
5148 | construct (including the colon) an identifier, and check only this | |
6258339f NC |
5149 | identifier for being the subject to parameter substitution. So for example |
5150 | this macro definition: | |
5151 | ||
5152 | @example | |
5153 | .macro label l | |
5154 | \l: | |
5155 | .endm | |
5156 | @end example | |
5157 | ||
5158 | might not work as expected. Invoking @samp{label foo} might not create a label | |
5159 | called @samp{foo} but instead just insert the text @samp{\l:} into the | |
5160 | assembler source, probably generating an error about an unrecognised | |
5161 | identifier. | |
5162 | ||
5163 | Similarly problems might occur with the period character (@samp{.}) | |
5164 | which is often allowed inside opcode names (and hence identifier names). So | |
5165 | for example constructing a macro to build an opcode from a base name and a | |
5166 | length specifier like this: | |
5167 | ||
5168 | @example | |
5169 | .macro opcode base length | |
5170 | \base.\length | |
5171 | .endm | |
5172 | @end example | |
5173 | ||
5174 | and invoking it as @samp{opcode store l} will not create a @samp{store.l} | |
5175 | instruction but instead generate some kind of error as the assembler tries to | |
5176 | interpret the text @samp{\base.\length}. | |
5177 | ||
5178 | There are several possible ways around this problem: | |
5179 | ||
5180 | @table @code | |
5181 | @item Insert white space | |
5182 | If it is possible to use white space characters then this is the simplest | |
5183 | solution. eg: | |
5184 | ||
5185 | @example | |
5186 | .macro label l | |
5187 | \l : | |
5188 | .endm | |
5189 | @end example | |
5190 | ||
5191 | @item Use @samp{\()} | |
5192 | The string @samp{\()} can be used to separate the end of a macro argument from | |
5193 | the following text. eg: | |
5194 | ||
5195 | @example | |
5196 | .macro opcode base length | |
5197 | \base\().\length | |
5198 | .endm | |
5199 | @end example | |
5200 | ||
5201 | @item Use the alternate macro syntax mode | |
5202 | In the alternative macro syntax mode the ampersand character (@samp{&}) can be | |
5203 | used as a separator. eg: | |
5e75c3ab JB |
5204 | |
5205 | @example | |
5206 | .altmacro | |
5207 | .macro label l | |
5208 | l&: | |
5209 | .endm | |
5210 | @end example | |
6258339f | 5211 | @end table |
5e75c3ab | 5212 | |
96e9638b BW |
5213 | Note: this problem of correctly identifying string parameters to pseudo ops |
5214 | also applies to the identifiers used in @code{.irp} (@pxref{Irp}) | |
5215 | and @code{.irpc} (@pxref{Irpc}) as well. | |
5e75c3ab | 5216 | |
252b5132 RH |
5217 | @item .endm |
5218 | @cindex @code{endm} directive | |
5219 | Mark the end of a macro definition. | |
5220 | ||
5221 | @item .exitm | |
5222 | @cindex @code{exitm} directive | |
5223 | Exit early from the current macro definition. | |
5224 | ||
5225 | @cindex number of macros executed | |
5226 | @cindex macros, count executed | |
5227 | @item \@@ | |
a4fb0134 | 5228 | @command{@value{AS}} maintains a counter of how many macros it has |
252b5132 RH |
5229 | executed in this pseudo-variable; you can copy that number to your |
5230 | output with @samp{\@@}, but @emph{only within a macro definition}. | |
5231 | ||
252b5132 RH |
5232 | @item LOCAL @var{name} [ , @dots{} ] |
5233 | @emph{Warning: @code{LOCAL} is only available if you select ``alternate | |
caa32fe5 NC |
5234 | macro syntax'' with @samp{--alternate} or @code{.altmacro}.} |
5235 | @xref{Altmacro,,@code{.altmacro}}. | |
5236 | @end ftable | |
252b5132 | 5237 | |
caa32fe5 NC |
5238 | @node Altmacro |
5239 | @section @code{.altmacro} | |
5240 | Enable alternate macro mode, enabling: | |
5241 | ||
5242 | @ftable @code | |
5243 | @item LOCAL @var{name} [ , @dots{} ] | |
5244 | One additional directive, @code{LOCAL}, is available. It is used to | |
5245 | generate a string replacement for each of the @var{name} arguments, and | |
252b5132 RH |
5246 | replace any instances of @var{name} in each macro expansion. The |
5247 | replacement string is unique in the assembly, and different for each | |
5248 | separate macro expansion. @code{LOCAL} allows you to write macros that | |
5249 | define symbols, without fear of conflict between separate macro expansions. | |
caa32fe5 NC |
5250 | |
5251 | @item String delimiters | |
5252 | You can write strings delimited in these other ways besides | |
5253 | @code{"@var{string}"}: | |
5254 | ||
5255 | @table @code | |
5256 | @item '@var{string}' | |
b45619c0 | 5257 | You can delimit strings with single-quote characters. |
caa32fe5 NC |
5258 | |
5259 | @item <@var{string}> | |
5260 | You can delimit strings with matching angle brackets. | |
5261 | @end table | |
5262 | ||
5263 | @item single-character string escape | |
5264 | To include any single character literally in a string (even if the | |
5265 | character would otherwise have some special meaning), you can prefix the | |
5266 | character with @samp{!} (an exclamation mark). For example, you can | |
5267 | write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}. | |
5268 | ||
5269 | @item Expression results as strings | |
5270 | You can write @samp{%@var{expr}} to evaluate the expression @var{expr} | |
5271 | and use the result as a string. | |
252b5132 RH |
5272 | @end ftable |
5273 | ||
caa32fe5 NC |
5274 | @node Noaltmacro |
5275 | @section @code{.noaltmacro} | |
96e9638b | 5276 | Disable alternate macro mode. @xref{Altmacro}. |
caa32fe5 | 5277 | |
252b5132 RH |
5278 | @node Nolist |
5279 | @section @code{.nolist} | |
5280 | ||
5281 | @cindex @code{nolist} directive | |
5282 | @cindex listing control, turning off | |
5283 | Control (in conjunction with the @code{.list} directive) whether or | |
5284 | not assembly listings are generated. These two directives maintain an | |
5285 | internal counter (which is zero initially). @code{.list} increments the | |
5286 | counter, and @code{.nolist} decrements it. Assembly listings are | |
5287 | generated whenever the counter is greater than zero. | |
5288 | ||
5289 | @node Octa | |
5290 | @section @code{.octa @var{bignums}} | |
5291 | ||
5292 | @c FIXME: double size emitted for "octa" on i960, others? Or warn? | |
5293 | @cindex @code{octa} directive | |
5294 | @cindex integer, 16-byte | |
5295 | @cindex sixteen byte integer | |
5296 | This directive expects zero or more bignums, separated by commas. For each | |
5297 | bignum, it emits a 16-byte integer. | |
5298 | ||
5299 | The term ``octa'' comes from contexts in which a ``word'' is two bytes; | |
5300 | hence @emph{octa}-word for 16 bytes. | |
5301 | ||
5302 | @node Org | |
5303 | @section @code{.org @var{new-lc} , @var{fill}} | |
5304 | ||
5305 | @cindex @code{org} directive | |
5306 | @cindex location counter, advancing | |
5307 | @cindex advancing location counter | |
5308 | @cindex current address, advancing | |
5309 | Advance the location counter of the current section to | |
5310 | @var{new-lc}. @var{new-lc} is either an absolute expression or an | |
5311 | expression with the same section as the current subsection. That is, | |
5312 | you can't use @code{.org} to cross sections: if @var{new-lc} has the | |
5313 | wrong section, the @code{.org} directive is ignored. To be compatible | |
5314 | with former assemblers, if the section of @var{new-lc} is absolute, | |
a4fb0134 | 5315 | @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc} |
252b5132 RH |
5316 | is the same as the current subsection. |
5317 | ||
5318 | @code{.org} may only increase the location counter, or leave it | |
5319 | unchanged; you cannot use @code{.org} to move the location counter | |
5320 | backwards. | |
5321 | ||
5322 | @c double negative used below "not undefined" because this is a specific | |
5323 | @c reference to "undefined" (as SEG_UNKNOWN is called in this manual) | |
5324 | @c section. doc@cygnus.com 18feb91 | |
a4fb0134 | 5325 | Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc} |
252b5132 RH |
5326 | may not be undefined. If you really detest this restriction we eagerly await |
5327 | a chance to share your improved assembler. | |
5328 | ||
5329 | Beware that the origin is relative to the start of the section, not | |
5330 | to the start of the subsection. This is compatible with other | |
5331 | people's assemblers. | |
5332 | ||
5333 | When the location counter (of the current subsection) is advanced, the | |
5334 | intervening bytes are filled with @var{fill} which should be an | |
5335 | absolute expression. If the comma and @var{fill} are omitted, | |
5336 | @var{fill} defaults to zero. | |
5337 | ||
5338 | @node P2align | |
5339 | @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} | |
5340 | ||
5341 | @cindex padding the location counter given a power of two | |
5342 | @cindex @code{p2align} directive | |
5343 | Pad the location counter (in the current subsection) to a particular | |
5344 | storage boundary. The first expression (which must be absolute) is the | |
5345 | number of low-order zero bits the location counter must have after | |
5346 | advancement. For example @samp{.p2align 3} advances the location | |
5347 | counter until it a multiple of 8. If the location counter is already a | |
5348 | multiple of 8, no change is needed. | |
5349 | ||
5350 | The second expression (also absolute) gives the fill value to be stored in the | |
5351 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
5352 | padding bytes are normally zero. However, on some systems, if the section is | |
5353 | marked as containing code and the fill value is omitted, the space is filled | |
5354 | with no-op instructions. | |
5355 | ||
5356 | The third expression is also absolute, and is also optional. If it is present, | |
5357 | it is the maximum number of bytes that should be skipped by this alignment | |
5358 | directive. If doing the alignment would require skipping more bytes than the | |
5359 | specified maximum, then the alignment is not done at all. You can omit the | |
5360 | fill value (the second argument) entirely by simply using two commas after the | |
5361 | required alignment; this can be useful if you want the alignment to be filled | |
5362 | with no-op instructions when appropriate. | |
5363 | ||
5364 | @cindex @code{p2alignw} directive | |
5365 | @cindex @code{p2alignl} directive | |
5366 | The @code{.p2alignw} and @code{.p2alignl} directives are variants of the | |
5367 | @code{.p2align} directive. The @code{.p2alignw} directive treats the fill | |
5368 | pattern as a two byte word value. The @code{.p2alignl} directives treats the | |
5369 | fill pattern as a four byte longword value. For example, @code{.p2alignw | |
5370 | 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be | |
5371 | filled in with the value 0x368d (the exact placement of the bytes depends upon | |
5372 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is | |
5373 | undefined. | |
5374 | ||
c91d2e08 NC |
5375 | @ifset ELF |
5376 | @node Previous | |
5377 | @section @code{.previous} | |
5378 | ||
c1253627 | 5379 | @cindex @code{previous} directive |
c91d2e08 NC |
5380 | @cindex Section Stack |
5381 | This is one of the ELF section stack manipulation directives. The others are | |
a349d9dd PB |
5382 | @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}), |
5383 | @code{.pushsection} (@pxref{PushSection}), and @code{.popsection} | |
5384 | (@pxref{PopSection}). | |
c91d2e08 NC |
5385 | |
5386 | This directive swaps the current section (and subsection) with most recently | |
8b040e0a | 5387 | referenced section/subsection pair prior to this one. Multiple |
c91d2e08 | 5388 | @code{.previous} directives in a row will flip between two sections (and their |
8b040e0a NC |
5389 | subsections). For example: |
5390 | ||
5391 | @smallexample | |
5392 | .section A | |
5393 | .subsection 1 | |
5394 | .word 0x1234 | |
5395 | .subsection 2 | |
5396 | .word 0x5678 | |
5397 | .previous | |
5398 | .word 0x9abc | |
5399 | @end smallexample | |
5400 | ||
5401 | Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of | |
5402 | section A. Whilst: | |
5403 | ||
5404 | @smallexample | |
5405 | .section A | |
5406 | .subsection 1 | |
5407 | # Now in section A subsection 1 | |
5408 | .word 0x1234 | |
5409 | .section B | |
5410 | .subsection 0 | |
5411 | # Now in section B subsection 0 | |
5412 | .word 0x5678 | |
5413 | .subsection 1 | |
5414 | # Now in section B subsection 1 | |
5415 | .word 0x9abc | |
5416 | .previous | |
5417 | # Now in section B subsection 0 | |
5418 | .word 0xdef0 | |
5419 | @end smallexample | |
5420 | ||
5421 | Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of | |
5422 | section B and 0x9abc into subsection 1 of section B. | |
c91d2e08 NC |
5423 | |
5424 | In terms of the section stack, this directive swaps the current section with | |
5425 | the top section on the section stack. | |
5426 | @end ifset | |
5427 | ||
5428 | @ifset ELF | |
5429 | @node PopSection | |
5430 | @section @code{.popsection} | |
5431 | ||
c1253627 | 5432 | @cindex @code{popsection} directive |
c91d2e08 NC |
5433 | @cindex Section Stack |
5434 | This is one of the ELF section stack manipulation directives. The others are | |
a349d9dd PB |
5435 | @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}), |
5436 | @code{.pushsection} (@pxref{PushSection}), and @code{.previous} | |
5437 | (@pxref{Previous}). | |
c91d2e08 NC |
5438 | |
5439 | This directive replaces the current section (and subsection) with the top | |
5440 | section (and subsection) on the section stack. This section is popped off the | |
5441 | stack. | |
c91d2e08 NC |
5442 | @end ifset |
5443 | ||
252b5132 RH |
5444 | @node Print |
5445 | @section @code{.print @var{string}} | |
5446 | ||
5447 | @cindex @code{print} directive | |
a4fb0134 | 5448 | @command{@value{AS}} will print @var{string} on the standard output during |
252b5132 RH |
5449 | assembly. You must put @var{string} in double quotes. |
5450 | ||
c91d2e08 NC |
5451 | @ifset ELF |
5452 | @node Protected | |
5453 | @section @code{.protected @var{names}} | |
5454 | ||
c1253627 NC |
5455 | @cindex @code{protected} directive |
5456 | @cindex visibility | |
ed9589d4 | 5457 | This is one of the ELF visibility directives. The other two are |
a349d9dd | 5458 | @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}). |
c91d2e08 NC |
5459 | |
5460 | This directive overrides the named symbols default visibility (which is set by | |
5461 | their binding: local, global or weak). The directive sets the visibility to | |
5462 | @code{protected} which means that any references to the symbols from within the | |
5463 | components that defines them must be resolved to the definition in that | |
5464 | component, even if a definition in another component would normally preempt | |
5465 | this. | |
5466 | @end ifset | |
5467 | ||
252b5132 RH |
5468 | @node Psize |
5469 | @section @code{.psize @var{lines} , @var{columns}} | |
5470 | ||
5471 | @cindex @code{psize} directive | |
5472 | @cindex listing control: paper size | |
5473 | @cindex paper size, for listings | |
5474 | Use this directive to declare the number of lines---and, optionally, the | |
5475 | number of columns---to use for each page, when generating listings. | |
5476 | ||
5477 | If you do not use @code{.psize}, listings use a default line-count | |
5478 | of 60. You may omit the comma and @var{columns} specification; the | |
5479 | default width is 200 columns. | |
5480 | ||
a4fb0134 | 5481 | @command{@value{AS}} generates formfeeds whenever the specified number of |
252b5132 RH |
5482 | lines is exceeded (or whenever you explicitly request one, using |
5483 | @code{.eject}). | |
5484 | ||
5485 | If you specify @var{lines} as @code{0}, no formfeeds are generated save | |
5486 | those explicitly specified with @code{.eject}. | |
5487 | ||
5488 | @node Purgem | |
5489 | @section @code{.purgem @var{name}} | |
5490 | ||
5491 | @cindex @code{purgem} directive | |
5492 | Undefine the macro @var{name}, so that later uses of the string will not be | |
5493 | expanded. @xref{Macro}. | |
5494 | ||
c91d2e08 NC |
5495 | @ifset ELF |
5496 | @node PushSection | |
9cfc3331 | 5497 | @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]} |
c91d2e08 | 5498 | |
c1253627 | 5499 | @cindex @code{pushsection} directive |
c91d2e08 NC |
5500 | @cindex Section Stack |
5501 | This is one of the ELF section stack manipulation directives. The others are | |
a349d9dd PB |
5502 | @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}), |
5503 | @code{.popsection} (@pxref{PopSection}), and @code{.previous} | |
5504 | (@pxref{Previous}). | |
c91d2e08 | 5505 | |
e9863d7f DJ |
5506 | This directive pushes the current section (and subsection) onto the |
5507 | top of the section stack, and then replaces the current section and | |
9cfc3331 L |
5508 | subsection with @code{name} and @code{subsection}. The optional |
5509 | @code{flags}, @code{type} and @code{arguments} are treated the same | |
5510 | as in the @code{.section} (@pxref{Section}) directive. | |
c91d2e08 NC |
5511 | @end ifset |
5512 | ||
252b5132 RH |
5513 | @node Quad |
5514 | @section @code{.quad @var{bignums}} | |
5515 | ||
5516 | @cindex @code{quad} directive | |
5517 | @code{.quad} expects zero or more bignums, separated by commas. For | |
5518 | each bignum, it emits | |
5519 | @ifclear bignum-16 | |
5520 | an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a | |
5521 | warning message; and just takes the lowest order 8 bytes of the bignum. | |
5522 | @cindex eight-byte integer | |
5523 | @cindex integer, 8-byte | |
5524 | ||
5525 | The term ``quad'' comes from contexts in which a ``word'' is two bytes; | |
5526 | hence @emph{quad}-word for 8 bytes. | |
5527 | @end ifclear | |
5528 | @ifset bignum-16 | |
5529 | a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a | |
5530 | warning message; and just takes the lowest order 16 bytes of the bignum. | |
5531 | @cindex sixteen-byte integer | |
5532 | @cindex integer, 16-byte | |
5533 | @end ifset | |
5534 | ||
05e9452c AM |
5535 | @node Reloc |
5536 | @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]} | |
5537 | ||
5538 | @cindex @code{reloc} directive | |
5539 | Generate a relocation at @var{offset} of type @var{reloc_name} with value | |
5540 | @var{expression}. If @var{offset} is a number, the relocation is generated in | |
5541 | the current section. If @var{offset} is an expression that resolves to a | |
5542 | symbol plus offset, the relocation is generated in the given symbol's section. | |
5543 | @var{expression}, if present, must resolve to a symbol plus addend or to an | |
5544 | absolute value, but note that not all targets support an addend. e.g. ELF REL | |
5545 | targets such as i386 store an addend in the section contents rather than in the | |
5546 | relocation. This low level interface does not support addends stored in the | |
5547 | section. | |
5548 | ||
252b5132 RH |
5549 | @node Rept |
5550 | @section @code{.rept @var{count}} | |
5551 | ||
5552 | @cindex @code{rept} directive | |
5553 | Repeat the sequence of lines between the @code{.rept} directive and the next | |
5554 | @code{.endr} directive @var{count} times. | |
5555 | ||
5556 | For example, assembling | |
5557 | ||
5558 | @example | |
5559 | .rept 3 | |
5560 | .long 0 | |
5561 | .endr | |
5562 | @end example | |
5563 | ||
5564 | is equivalent to assembling | |
5565 | ||
5566 | @example | |
5567 | .long 0 | |
5568 | .long 0 | |
5569 | .long 0 | |
5570 | @end example | |
5571 | ||
5572 | @node Sbttl | |
5573 | @section @code{.sbttl "@var{subheading}"} | |
5574 | ||
5575 | @cindex @code{sbttl} directive | |
5576 | @cindex subtitles for listings | |
5577 | @cindex listing control: subtitle | |
5578 | Use @var{subheading} as the title (third line, immediately after the | |
5579 | title line) when generating assembly listings. | |
5580 | ||
5581 | This directive affects subsequent pages, as well as the current page if | |
5582 | it appears within ten lines of the top of a page. | |
5583 | ||
5584 | @ifset COFF | |
5585 | @node Scl | |
5586 | @section @code{.scl @var{class}} | |
5587 | ||
5588 | @cindex @code{scl} directive | |
5589 | @cindex symbol storage class (COFF) | |
5590 | @cindex COFF symbol storage class | |
5591 | Set the storage-class value for a symbol. This directive may only be | |
5592 | used inside a @code{.def}/@code{.endef} pair. Storage class may flag | |
5593 | whether a symbol is static or external, or it may record further | |
5594 | symbolic debugging information. | |
5595 | @ifset BOUT | |
5596 | ||
5597 | The @samp{.scl} directive is primarily associated with COFF output; when | |
a4fb0134 | 5598 | configured to generate @code{b.out} output format, @command{@value{AS}} |
252b5132 RH |
5599 | accepts this directive but ignores it. |
5600 | @end ifset | |
5601 | @end ifset | |
5602 | ||
c1253627 | 5603 | @ifset COFF-ELF |
252b5132 | 5604 | @node Section |
c1253627 | 5605 | @section @code{.section @var{name}} |
252b5132 | 5606 | |
252b5132 RH |
5607 | @cindex named section |
5608 | Use the @code{.section} directive to assemble the following code into a section | |
5609 | named @var{name}. | |
5610 | ||
5611 | This directive is only supported for targets that actually support arbitrarily | |
5612 | named sections; on @code{a.out} targets, for example, it is not accepted, even | |
5613 | with a standard @code{a.out} section name. | |
5614 | ||
c1253627 NC |
5615 | @ifset COFF |
5616 | @ifset ELF | |
5617 | @c only print the extra heading if both COFF and ELF are set | |
5618 | @subheading COFF Version | |
5619 | @end ifset | |
5620 | ||
5621 | @cindex @code{section} directive (COFF version) | |
252b5132 RH |
5622 | For COFF targets, the @code{.section} directive is used in one of the following |
5623 | ways: | |
c91d2e08 | 5624 | |
252b5132 RH |
5625 | @smallexample |
5626 | .section @var{name}[, "@var{flags}"] | |
4e188d17 | 5627 | .section @var{name}[, @var{subsection}] |
252b5132 RH |
5628 | @end smallexample |
5629 | ||
5630 | If the optional argument is quoted, it is taken as flags to use for the | |
5631 | section. Each flag is a single character. The following flags are recognized: | |
5632 | @table @code | |
5633 | @item b | |
5634 | bss section (uninitialized data) | |
5635 | @item n | |
5636 | section is not loaded | |
5637 | @item w | |
5638 | writable section | |
5639 | @item d | |
5640 | data section | |
5641 | @item r | |
5642 | read-only section | |
5643 | @item x | |
5644 | executable section | |
2dcc60be ILT |
5645 | @item s |
5646 | shared section (meaningful for PE targets) | |
6ff96af6 NC |
5647 | @item a |
5648 | ignored. (For compatibility with the ELF version) | |
252b5132 RH |
5649 | @end table |
5650 | ||
5651 | If no flags are specified, the default flags depend upon the section name. If | |
5652 | the section name is not recognized, the default will be for the section to be | |
7e84d676 NC |
5653 | loaded and writable. Note the @code{n} and @code{w} flags remove attributes |
5654 | from the section, rather than adding them, so if they are used on their own it | |
5655 | will be as if no flags had been specified at all. | |
252b5132 RH |
5656 | |
5657 | If the optional argument to the @code{.section} directive is not quoted, it is | |
4e188d17 | 5658 | taken as a subsection number (@pxref{Sub-Sections}). |
c1253627 | 5659 | @end ifset |
252b5132 RH |
5660 | |
5661 | @ifset ELF | |
c1253627 NC |
5662 | @ifset COFF |
5663 | @c only print the extra heading if both COFF and ELF are set | |
5664 | @subheading ELF Version | |
5665 | @end ifset | |
5666 | ||
c91d2e08 NC |
5667 | @cindex Section Stack |
5668 | This is one of the ELF section stack manipulation directives. The others are | |
a349d9dd PB |
5669 | @code{.subsection} (@pxref{SubSection}), @code{.pushsection} |
5670 | (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and | |
5671 | @code{.previous} (@pxref{Previous}). | |
c91d2e08 | 5672 | |
c1253627 | 5673 | @cindex @code{section} directive (ELF version) |
252b5132 | 5674 | For ELF targets, the @code{.section} directive is used like this: |
c91d2e08 | 5675 | |
252b5132 | 5676 | @smallexample |
7047dd1e | 5677 | .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]] |
252b5132 | 5678 | @end smallexample |
c91d2e08 | 5679 | |
252b5132 | 5680 | The optional @var{flags} argument is a quoted string which may contain any |
a349d9dd | 5681 | combination of the following characters: |
252b5132 RH |
5682 | @table @code |
5683 | @item a | |
5684 | section is allocatable | |
5685 | @item w | |
5686 | section is writable | |
5687 | @item x | |
5688 | section is executable | |
ec38dd05 JJ |
5689 | @item M |
5690 | section is mergeable | |
5691 | @item S | |
5692 | section contains zero terminated strings | |
22fe14ad NC |
5693 | @item G |
5694 | section is a member of a section group | |
5695 | @item T | |
5696 | section is used for thread-local-storage | |
252b5132 RH |
5697 | @end table |
5698 | ||
5699 | The optional @var{type} argument may contain one of the following constants: | |
5700 | @table @code | |
5701 | @item @@progbits | |
5702 | section contains data | |
5703 | @item @@nobits | |
5704 | section does not contain data (i.e., section only occupies space) | |
22fe14ad NC |
5705 | @item @@note |
5706 | section contains data which is used by things other than the program | |
10b016c2 PB |
5707 | @item @@init_array |
5708 | section contains an array of pointers to init functions | |
5709 | @item @@fini_array | |
5710 | section contains an array of pointers to finish functions | |
5711 | @item @@preinit_array | |
5712 | section contains an array of pointers to pre-init functions | |
252b5132 RH |
5713 | @end table |
5714 | ||
10b016c2 PB |
5715 | Many targets only support the first three section types. |
5716 | ||
ececec60 NC |
5717 | Note on targets where the @code{@@} character is the start of a comment (eg |
5718 | ARM) then another character is used instead. For example the ARM port uses the | |
5719 | @code{%} character. | |
5720 | ||
22fe14ad | 5721 | If @var{flags} contains the @code{M} symbol then the @var{type} argument must |
96e9638b | 5722 | be specified as well as an extra argument---@var{entsize}---like this: |
22fe14ad NC |
5723 | |
5724 | @smallexample | |
5725 | .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize} | |
5726 | @end smallexample | |
5727 | ||
5728 | Sections with the @code{M} flag but not @code{S} flag must contain fixed size | |
5729 | constants, each @var{entsize} octets long. Sections with both @code{M} and | |
5730 | @code{S} must contain zero terminated strings where each character is | |
5731 | @var{entsize} bytes long. The linker may remove duplicates within sections with | |
5732 | the same name, same entity size and same flags. @var{entsize} must be an | |
5733 | absolute expression. | |
5734 | ||
5735 | If @var{flags} contains the @code{G} symbol then the @var{type} argument must | |
5736 | be present along with an additional field like this: | |
5737 | ||
5738 | @smallexample | |
5739 | .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}] | |
5740 | @end smallexample | |
5741 | ||
5742 | The @var{GroupName} field specifies the name of the section group to which this | |
5743 | particular section belongs. The optional linkage field can contain: | |
5744 | @table @code | |
5745 | @item comdat | |
5746 | indicates that only one copy of this section should be retained | |
5747 | @item .gnu.linkonce | |
5748 | an alias for comdat | |
5749 | @end table | |
5750 | ||
96e9638b | 5751 | Note: if both the @var{M} and @var{G} flags are present then the fields for |
22fe14ad NC |
5752 | the Merge flag should come first, like this: |
5753 | ||
5754 | @smallexample | |
5755 | .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}] | |
5756 | @end smallexample | |
ec38dd05 | 5757 | |
252b5132 RH |
5758 | If no flags are specified, the default flags depend upon the section name. If |
5759 | the section name is not recognized, the default will be for the section to have | |
5760 | none of the above flags: it will not be allocated in memory, nor writable, nor | |
5761 | executable. The section will contain data. | |
5762 | ||
5763 | For ELF targets, the assembler supports another type of @code{.section} | |
5764 | directive for compatibility with the Solaris assembler: | |
c91d2e08 | 5765 | |
252b5132 RH |
5766 | @smallexample |
5767 | .section "@var{name}"[, @var{flags}...] | |
5768 | @end smallexample | |
c91d2e08 | 5769 | |
252b5132 RH |
5770 | Note that the section name is quoted. There may be a sequence of comma |
5771 | separated flags: | |
5772 | @table @code | |
5773 | @item #alloc | |
5774 | section is allocatable | |
5775 | @item #write | |
5776 | section is writable | |
5777 | @item #execinstr | |
5778 | section is executable | |
22fe14ad NC |
5779 | @item #tls |
5780 | section is used for thread local storage | |
252b5132 | 5781 | @end table |
c91d2e08 | 5782 | |
e9863d7f DJ |
5783 | This directive replaces the current section and subsection. See the |
5784 | contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for | |
5785 | some examples of how this directive and the other section stack directives | |
5786 | work. | |
c1253627 NC |
5787 | @end ifset |
5788 | @end ifset | |
252b5132 RH |
5789 | |
5790 | @node Set | |
5791 | @section @code{.set @var{symbol}, @var{expression}} | |
5792 | ||
5793 | @cindex @code{set} directive | |
5794 | @cindex symbol value, setting | |
5795 | Set the value of @var{symbol} to @var{expression}. This | |
5796 | changes @var{symbol}'s value and type to conform to | |
5797 | @var{expression}. If @var{symbol} was flagged as external, it remains | |
5798 | flagged (@pxref{Symbol Attributes}). | |
5799 | ||
5800 | You may @code{.set} a symbol many times in the same assembly. | |
5801 | ||
5802 | If you @code{.set} a global symbol, the value stored in the object | |
5803 | file is the last value stored into it. | |
5804 | ||
5805 | @ifset HPPA | |
5806 | The syntax for @code{set} on the HPPA is | |
5807 | @samp{@var{symbol} .set @var{expression}}. | |
5808 | @end ifset | |
5809 | ||
3c9b82ba NC |
5810 | @ifset Z80 |
5811 | On Z80 @code{set} is a real instruction, use | |
5812 | @samp{@var{symbol} defl @var{expression}} instead. | |
5813 | @end ifset | |
5814 | ||
252b5132 RH |
5815 | @node Short |
5816 | @section @code{.short @var{expressions}} | |
5817 | ||
5818 | @cindex @code{short} directive | |
5819 | @ifset GENERIC | |
5820 | @code{.short} is normally the same as @samp{.word}. | |
5821 | @xref{Word,,@code{.word}}. | |
5822 | ||
5823 | In some configurations, however, @code{.short} and @code{.word} generate | |
96e9638b | 5824 | numbers of different lengths. @xref{Machine Dependencies}. |
252b5132 RH |
5825 | @end ifset |
5826 | @ifclear GENERIC | |
5827 | @ifset W16 | |
5828 | @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}. | |
5829 | @end ifset | |
5830 | @ifset W32 | |
5831 | This expects zero or more @var{expressions}, and emits | |
5832 | a 16 bit number for each. | |
5833 | @end ifset | |
5834 | @end ifclear | |
5835 | ||
5836 | @node Single | |
5837 | @section @code{.single @var{flonums}} | |
5838 | ||
5839 | @cindex @code{single} directive | |
5840 | @cindex floating point numbers (single) | |
5841 | This directive assembles zero or more flonums, separated by commas. It | |
5842 | has the same effect as @code{.float}. | |
5843 | @ifset GENERIC | |
5844 | The exact kind of floating point numbers emitted depends on how | |
a4fb0134 | 5845 | @command{@value{AS}} is configured. @xref{Machine Dependencies}. |
252b5132 RH |
5846 | @end ifset |
5847 | @ifclear GENERIC | |
5848 | @ifset IEEEFLOAT | |
5849 | On the @value{TARGET} family, @code{.single} emits 32-bit floating point | |
5850 | numbers in @sc{ieee} format. | |
5851 | @end ifset | |
5852 | @end ifclear | |
5853 | ||
c1253627 | 5854 | @ifset COFF-ELF |
252b5132 | 5855 | @node Size |
c1253627 | 5856 | @section @code{.size} |
c91d2e08 | 5857 | |
c1253627 NC |
5858 | This directive is used to set the size associated with a symbol. |
5859 | ||
5860 | @ifset COFF | |
5861 | @ifset ELF | |
5862 | @c only print the extra heading if both COFF and ELF are set | |
5863 | @subheading COFF Version | |
5864 | @end ifset | |
5865 | ||
5866 | @cindex @code{size} directive (COFF version) | |
5867 | For COFF targets, the @code{.size} directive is only permitted inside | |
5868 | @code{.def}/@code{.endef} pairs. It is used like this: | |
5869 | ||
5870 | @smallexample | |
5871 | .size @var{expression} | |
5872 | @end smallexample | |
252b5132 | 5873 | |
c91d2e08 | 5874 | @ifset BOUT |
252b5132 | 5875 | @samp{.size} is only meaningful when generating COFF format output; when |
a4fb0134 | 5876 | @command{@value{AS}} is generating @code{b.out}, it accepts this directive but |
252b5132 RH |
5877 | ignores it. |
5878 | @end ifset | |
c1253627 | 5879 | @end ifset |
c91d2e08 | 5880 | |
c1253627 NC |
5881 | @ifset ELF |
5882 | @ifset COFF | |
5883 | @c only print the extra heading if both COFF and ELF are set | |
5884 | @subheading ELF Version | |
5885 | @end ifset | |
5886 | ||
5887 | @cindex @code{size} directive (ELF version) | |
5888 | For ELF targets, the @code{.size} directive is used like this: | |
c91d2e08 | 5889 | |
c1253627 NC |
5890 | @smallexample |
5891 | .size @var{name} , @var{expression} | |
5892 | @end smallexample | |
5893 | ||
5894 | This directive sets the size associated with a symbol @var{name}. | |
c91d2e08 NC |
5895 | The size in bytes is computed from @var{expression} which can make use of label |
5896 | arithmetic. This directive is typically used to set the size of function | |
5897 | symbols. | |
c1253627 NC |
5898 | @end ifset |
5899 | @end ifset | |
252b5132 RH |
5900 | |
5901 | @node Sleb128 | |
5902 | @section @code{.sleb128 @var{expressions}} | |
5903 | ||
5904 | @cindex @code{sleb128} directive | |
5905 | @var{sleb128} stands for ``signed little endian base 128.'' This is a | |
5906 | compact, variable length representation of numbers used by the DWARF | |
96e9638b | 5907 | symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}. |
252b5132 RH |
5908 | |
5909 | @ifclear no-space-dir | |
5910 | @node Skip | |
5911 | @section @code{.skip @var{size} , @var{fill}} | |
5912 | ||
5913 | @cindex @code{skip} directive | |
5914 | @cindex filling memory | |
5915 | This directive emits @var{size} bytes, each of value @var{fill}. Both | |
5916 | @var{size} and @var{fill} are absolute expressions. If the comma and | |
5917 | @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as | |
5918 | @samp{.space}. | |
5919 | ||
5920 | @node Space | |
5921 | @section @code{.space @var{size} , @var{fill}} | |
5922 | ||
5923 | @cindex @code{space} directive | |
5924 | @cindex filling memory | |
5925 | This directive emits @var{size} bytes, each of value @var{fill}. Both | |
5926 | @var{size} and @var{fill} are absolute expressions. If the comma | |
5927 | and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same | |
5928 | as @samp{.skip}. | |
5929 | ||
5930 | @ifset HPPA | |
5931 | @quotation | |
5932 | @emph{Warning:} @code{.space} has a completely different meaning for HPPA | |
5933 | targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800 | |
5934 | Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the | |
5935 | @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives}, | |
5936 | for a summary. | |
5937 | @end quotation | |
5938 | @end ifset | |
5939 | @end ifclear | |
5940 | ||
252b5132 RH |
5941 | @ifset have-stabs |
5942 | @node Stab | |
5943 | @section @code{.stabd, .stabn, .stabs} | |
5944 | ||
5945 | @cindex symbolic debuggers, information for | |
5946 | @cindex @code{stab@var{x}} directives | |
5947 | There are three directives that begin @samp{.stab}. | |
5948 | All emit symbols (@pxref{Symbols}), for use by symbolic debuggers. | |
a4fb0134 | 5949 | The symbols are not entered in the @command{@value{AS}} hash table: they |
252b5132 RH |
5950 | cannot be referenced elsewhere in the source file. |
5951 | Up to five fields are required: | |
5952 | ||
5953 | @table @var | |
5954 | @item string | |
5955 | This is the symbol's name. It may contain any character except | |
5956 | @samp{\000}, so is more general than ordinary symbol names. Some | |
5957 | debuggers used to code arbitrarily complex structures into symbol names | |
5958 | using this field. | |
5959 | ||
5960 | @item type | |
5961 | An absolute expression. The symbol's type is set to the low 8 bits of | |
5962 | this expression. Any bit pattern is permitted, but @code{@value{LD}} | |
5963 | and debuggers choke on silly bit patterns. | |
5964 | ||
5965 | @item other | |
5966 | An absolute expression. The symbol's ``other'' attribute is set to the | |
5967 | low 8 bits of this expression. | |
5968 | ||
5969 | @item desc | |
5970 | An absolute expression. The symbol's descriptor is set to the low 16 | |
5971 | bits of this expression. | |
5972 | ||
5973 | @item value | |
5974 | An absolute expression which becomes the symbol's value. | |
5975 | @end table | |
5976 | ||
5977 | If a warning is detected while reading a @code{.stabd}, @code{.stabn}, | |
5978 | or @code{.stabs} statement, the symbol has probably already been created; | |
5979 | you get a half-formed symbol in your object file. This is | |
5980 | compatible with earlier assemblers! | |
5981 | ||
5982 | @table @code | |
5983 | @cindex @code{stabd} directive | |
5984 | @item .stabd @var{type} , @var{other} , @var{desc} | |
5985 | ||
5986 | The ``name'' of the symbol generated is not even an empty string. | |
5987 | It is a null pointer, for compatibility. Older assemblers used a | |
5988 | null pointer so they didn't waste space in object files with empty | |
5989 | strings. | |
5990 | ||
5991 | The symbol's value is set to the location counter, | |
5992 | relocatably. When your program is linked, the value of this symbol | |
5993 | is the address of the location counter when the @code{.stabd} was | |
5994 | assembled. | |
5995 | ||
5996 | @cindex @code{stabn} directive | |
5997 | @item .stabn @var{type} , @var{other} , @var{desc} , @var{value} | |
5998 | The name of the symbol is set to the empty string @code{""}. | |
5999 | ||
6000 | @cindex @code{stabs} directive | |
6001 | @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value} | |
6002 | All five fields are specified. | |
6003 | @end table | |
6004 | @end ifset | |
6005 | @c end have-stabs | |
6006 | ||
6007 | @node String | |
38a57ae7 NC |
6008 | @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16} |
6009 | "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}" | |
252b5132 RH |
6010 | |
6011 | @cindex string, copying to object file | |
38a57ae7 NC |
6012 | @cindex string8, copying to object file |
6013 | @cindex string16, copying to object file | |
6014 | @cindex string32, copying to object file | |
6015 | @cindex string64, copying to object file | |
252b5132 | 6016 | @cindex @code{string} directive |
38a57ae7 NC |
6017 | @cindex @code{string8} directive |
6018 | @cindex @code{string16} directive | |
6019 | @cindex @code{string32} directive | |
6020 | @cindex @code{string64} directive | |
252b5132 RH |
6021 | |
6022 | Copy the characters in @var{str} to the object file. You may specify more than | |
6023 | one string to copy, separated by commas. Unless otherwise specified for a | |
6024 | particular machine, the assembler marks the end of each string with a 0 byte. | |
6025 | You can use any of the escape sequences described in @ref{Strings,,Strings}. | |
6026 | ||
38a57ae7 NC |
6027 | The variants @code{string16}, @code{string32} and @code{string64} differ from |
6028 | the @code{string} pseudo opcode in that each 8-bit character from @var{str} is | |
6029 | copied and expanded to 16, 32 or 64 bits respectively. The expanded characters | |
6030 | are stored in target endianness byte order. | |
6031 | ||
6032 | Example: | |
6033 | @smallexample | |
6034 | .string32 "BYE" | |
6035 | expands to: | |
6036 | .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */ | |
6037 | .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */ | |
6038 | @end smallexample | |
6039 | ||
6040 | ||
252b5132 RH |
6041 | @node Struct |
6042 | @section @code{.struct @var{expression}} | |
6043 | ||
6044 | @cindex @code{struct} directive | |
6045 | Switch to the absolute section, and set the section offset to @var{expression}, | |
6046 | which must be an absolute expression. You might use this as follows: | |
6047 | @smallexample | |
6048 | .struct 0 | |
6049 | field1: | |
6050 | .struct field1 + 4 | |
6051 | field2: | |
6052 | .struct field2 + 4 | |
6053 | field3: | |
6054 | @end smallexample | |
6055 | This would define the symbol @code{field1} to have the value 0, the symbol | |
6056 | @code{field2} to have the value 4, and the symbol @code{field3} to have the | |
6057 | value 8. Assembly would be left in the absolute section, and you would need to | |
6058 | use a @code{.section} directive of some sort to change to some other section | |
6059 | before further assembly. | |
6060 | ||
c91d2e08 NC |
6061 | @ifset ELF |
6062 | @node SubSection | |
6063 | @section @code{.subsection @var{name}} | |
6064 | ||
c1253627 | 6065 | @cindex @code{subsection} directive |
c91d2e08 NC |
6066 | @cindex Section Stack |
6067 | This is one of the ELF section stack manipulation directives. The others are | |
a349d9dd PB |
6068 | @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}), |
6069 | @code{.popsection} (@pxref{PopSection}), and @code{.previous} | |
6070 | (@pxref{Previous}). | |
c91d2e08 NC |
6071 | |
6072 | This directive replaces the current subsection with @code{name}. The current | |
6073 | section is not changed. The replaced subsection is put onto the section stack | |
6074 | in place of the then current top of stack subsection. | |
c91d2e08 NC |
6075 | @end ifset |
6076 | ||
252b5132 RH |
6077 | @ifset ELF |
6078 | @node Symver | |
6079 | @section @code{.symver} | |
6080 | @cindex @code{symver} directive | |
6081 | @cindex symbol versioning | |
6082 | @cindex versions of symbols | |
6083 | Use the @code{.symver} directive to bind symbols to specific version nodes | |
6084 | within a source file. This is only supported on ELF platforms, and is | |
6085 | typically used when assembling files to be linked into a shared library. | |
6086 | There are cases where it may make sense to use this in objects to be bound | |
6087 | into an application itself so as to override a versioned symbol from a | |
6088 | shared library. | |
6089 | ||
79082ff0 | 6090 | For ELF targets, the @code{.symver} directive can be used like this: |
252b5132 RH |
6091 | @smallexample |
6092 | .symver @var{name}, @var{name2@@nodename} | |
6093 | @end smallexample | |
339681c0 | 6094 | If the symbol @var{name} is defined within the file |
79082ff0 | 6095 | being assembled, the @code{.symver} directive effectively creates a symbol |
252b5132 RH |
6096 | alias with the name @var{name2@@nodename}, and in fact the main reason that we |
6097 | just don't try and create a regular alias is that the @var{@@} character isn't | |
6098 | permitted in symbol names. The @var{name2} part of the name is the actual name | |
6099 | of the symbol by which it will be externally referenced. The name @var{name} | |
6100 | itself is merely a name of convenience that is used so that it is possible to | |
6101 | have definitions for multiple versions of a function within a single source | |
6102 | file, and so that the compiler can unambiguously know which version of a | |
6103 | function is being mentioned. The @var{nodename} portion of the alias should be | |
6104 | the name of a node specified in the version script supplied to the linker when | |
6105 | building a shared library. If you are attempting to override a versioned | |
6106 | symbol from a shared library, then @var{nodename} should correspond to the | |
6107 | nodename of the symbol you are trying to override. | |
339681c0 L |
6108 | |
6109 | If the symbol @var{name} is not defined within the file being assembled, all | |
6110 | references to @var{name} will be changed to @var{name2@@nodename}. If no | |
6111 | reference to @var{name} is made, @var{name2@@nodename} will be removed from the | |
6112 | symbol table. | |
79082ff0 L |
6113 | |
6114 | Another usage of the @code{.symver} directive is: | |
6115 | @smallexample | |
6116 | .symver @var{name}, @var{name2@@@@nodename} | |
6117 | @end smallexample | |
6118 | In this case, the symbol @var{name} must exist and be defined within | |
a349d9dd | 6119 | the file being assembled. It is similar to @var{name2@@nodename}. The |
79082ff0 L |
6120 | difference is @var{name2@@@@nodename} will also be used to resolve |
6121 | references to @var{name2} by the linker. | |
6122 | ||
6123 | The third usage of the @code{.symver} directive is: | |
6124 | @smallexample | |
6125 | .symver @var{name}, @var{name2@@@@@@nodename} | |
6126 | @end smallexample | |
6127 | When @var{name} is not defined within the | |
6128 | file being assembled, it is treated as @var{name2@@nodename}. When | |
6129 | @var{name} is defined within the file being assembled, the symbol | |
6130 | name, @var{name}, will be changed to @var{name2@@@@nodename}. | |
252b5132 RH |
6131 | @end ifset |
6132 | ||
6133 | @ifset COFF | |
6134 | @node Tag | |
6135 | @section @code{.tag @var{structname}} | |
6136 | ||
6137 | @cindex COFF structure debugging | |
6138 | @cindex structure debugging, COFF | |
6139 | @cindex @code{tag} directive | |
6140 | This directive is generated by compilers to include auxiliary debugging | |
6141 | information in the symbol table. It is only permitted inside | |
6142 | @code{.def}/@code{.endef} pairs. Tags are used to link structure | |
6143 | definitions in the symbol table with instances of those structures. | |
6144 | @ifset BOUT | |
6145 | ||
6146 | @samp{.tag} is only used when generating COFF format output; when | |
a4fb0134 | 6147 | @command{@value{AS}} is generating @code{b.out}, it accepts this directive but |
252b5132 RH |
6148 | ignores it. |
6149 | @end ifset | |
6150 | @end ifset | |
6151 | ||
6152 | @node Text | |
6153 | @section @code{.text @var{subsection}} | |
6154 | ||
6155 | @cindex @code{text} directive | |
a4fb0134 | 6156 | Tells @command{@value{AS}} to assemble the following statements onto the end of |
252b5132 RH |
6157 | the text subsection numbered @var{subsection}, which is an absolute |
6158 | expression. If @var{subsection} is omitted, subsection number zero | |
6159 | is used. | |
6160 | ||
6161 | @node Title | |
6162 | @section @code{.title "@var{heading}"} | |
6163 | ||
6164 | @cindex @code{title} directive | |
6165 | @cindex listing control: title line | |
6166 | Use @var{heading} as the title (second line, immediately after the | |
6167 | source file name and pagenumber) when generating assembly listings. | |
6168 | ||
6169 | This directive affects subsequent pages, as well as the current page if | |
6170 | it appears within ten lines of the top of a page. | |
6171 | ||
c1253627 | 6172 | @ifset COFF-ELF |
252b5132 | 6173 | @node Type |
c1253627 NC |
6174 | @section @code{.type} |
6175 | ||
6176 | This directive is used to set the type of a symbol. | |
6177 | ||
6178 | @ifset COFF | |
6179 | @ifset ELF | |
6180 | @c only print the extra heading if both COFF and ELF are set | |
6181 | @subheading COFF Version | |
6182 | @end ifset | |
252b5132 RH |
6183 | |
6184 | @cindex COFF symbol type | |
6185 | @cindex symbol type, COFF | |
c1253627 NC |
6186 | @cindex @code{type} directive (COFF version) |
6187 | For COFF targets, this directive is permitted only within | |
6188 | @code{.def}/@code{.endef} pairs. It is used like this: | |
6189 | ||
6190 | @smallexample | |
6191 | .type @var{int} | |
6192 | @end smallexample | |
6193 | ||
6194 | This records the integer @var{int} as the type attribute of a symbol table | |
6195 | entry. | |
252b5132 | 6196 | |
c91d2e08 | 6197 | @ifset BOUT |
252b5132 | 6198 | @samp{.type} is associated only with COFF format output; when |
a4fb0134 | 6199 | @command{@value{AS}} is configured for @code{b.out} output, it accepts this |
252b5132 RH |
6200 | directive but ignores it. |
6201 | @end ifset | |
c1253627 | 6202 | @end ifset |
c91d2e08 | 6203 | |
c1253627 NC |
6204 | @ifset ELF |
6205 | @ifset COFF | |
6206 | @c only print the extra heading if both COFF and ELF are set | |
6207 | @subheading ELF Version | |
6208 | @end ifset | |
c91d2e08 NC |
6209 | |
6210 | @cindex ELF symbol type | |
6211 | @cindex symbol type, ELF | |
c1253627 NC |
6212 | @cindex @code{type} directive (ELF version) |
6213 | For ELF targets, the @code{.type} directive is used like this: | |
6214 | ||
6215 | @smallexample | |
6216 | .type @var{name} , @var{type description} | |
6217 | @end smallexample | |
6218 | ||
6219 | This sets the type of symbol @var{name} to be either a | |
a349d9dd | 6220 | function symbol or an object symbol. There are five different syntaxes |
c91d2e08 | 6221 | supported for the @var{type description} field, in order to provide |
28c9d252 | 6222 | compatibility with various other assemblers. |
58ab4f3d MM |
6223 | |
6224 | Because some of the characters used in these syntaxes (such as @samp{@@} and | |
6225 | @samp{#}) are comment characters for some architectures, some of the syntaxes | |
6226 | below do not work on all architectures. The first variant will be accepted by | |
6227 | the GNU assembler on all architectures so that variant should be used for | |
6228 | maximum portability, if you do not need to assemble your code with other | |
6229 | assemblers. | |
6230 | ||
6231 | The syntaxes supported are: | |
c91d2e08 NC |
6232 | |
6233 | @smallexample | |
5671778d NC |
6234 | .type <name> STT_<TYPE_IN_UPPER_CASE> |
6235 | .type <name>,#<type> | |
6236 | .type <name>,@@<type> | |
6237 | .type <name>,%>type> | |
6238 | .type <name>,"<type>" | |
6239 | @end smallexample | |
6240 | ||
6241 | The types supported are: | |
58ab4f3d | 6242 | |
5671778d NC |
6243 | @table @gcctabopt |
6244 | @item STT_FUNC | |
6245 | @itemx function | |
6246 | Mark the symbol as being a function name. | |
c91d2e08 | 6247 | |
5671778d NC |
6248 | @item STT_OBJECT |
6249 | @itemx object | |
6250 | Mark the symbol as being a data object. | |
6251 | ||
6252 | @item STT_TLS | |
6253 | @itemx tls_object | |
6254 | Mark the symbol as being a thead-local data object. | |
6255 | ||
6256 | @item STT_COMMON | |
6257 | @itemx common | |
6258 | Mark the symbol as being a common data object. | |
6259 | @end table | |
6260 | ||
6261 | Note: Some targets support extra types in addition to those listed above. | |
c91d2e08 | 6262 | |
c1253627 NC |
6263 | @end ifset |
6264 | @end ifset | |
c91d2e08 NC |
6265 | |
6266 | @node Uleb128 | |
6267 | @section @code{.uleb128 @var{expressions}} | |
6268 | ||
6269 | @cindex @code{uleb128} directive | |
6270 | @var{uleb128} stands for ``unsigned little endian base 128.'' This is a | |
6271 | compact, variable length representation of numbers used by the DWARF | |
96e9638b | 6272 | symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}. |
252b5132 RH |
6273 | |
6274 | @ifset COFF | |
6275 | @node Val | |
6276 | @section @code{.val @var{addr}} | |
6277 | ||
6278 | @cindex @code{val} directive | |
6279 | @cindex COFF value attribute | |
6280 | @cindex value attribute, COFF | |
6281 | This directive, permitted only within @code{.def}/@code{.endef} pairs, | |
6282 | records the address @var{addr} as the value attribute of a symbol table | |
6283 | entry. | |
6284 | @ifset BOUT | |
6285 | ||
a4fb0134 | 6286 | @samp{.val} is used only for COFF output; when @command{@value{AS}} is |
252b5132 RH |
6287 | configured for @code{b.out}, it accepts this directive but ignores it. |
6288 | @end ifset | |
6289 | @end ifset | |
6290 | ||
2e13b764 | 6291 | @ifset ELF |
c91d2e08 NC |
6292 | @node Version |
6293 | @section @code{.version "@var{string}"} | |
2e13b764 | 6294 | |
c1253627 | 6295 | @cindex @code{version} directive |
c91d2e08 NC |
6296 | This directive creates a @code{.note} section and places into it an ELF |
6297 | formatted note of type NT_VERSION. The note's name is set to @code{string}. | |
9a297610 | 6298 | @end ifset |
2e13b764 | 6299 | |
c91d2e08 NC |
6300 | @ifset ELF |
6301 | @node VTableEntry | |
6302 | @section @code{.vtable_entry @var{table}, @var{offset}} | |
2e13b764 | 6303 | |
653cfe85 | 6304 | @cindex @code{vtable_entry} directive |
c91d2e08 NC |
6305 | This directive finds or creates a symbol @code{table} and creates a |
6306 | @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}. | |
2e13b764 | 6307 | |
c91d2e08 NC |
6308 | @node VTableInherit |
6309 | @section @code{.vtable_inherit @var{child}, @var{parent}} | |
2e13b764 | 6310 | |
653cfe85 | 6311 | @cindex @code{vtable_inherit} directive |
c91d2e08 NC |
6312 | This directive finds the symbol @code{child} and finds or creates the symbol |
6313 | @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the | |
a349d9dd | 6314 | parent whose addend is the value of the child symbol. As a special case the |
96e9638b | 6315 | parent name of @code{0} is treated as referring to the @code{*ABS*} section. |
c91d2e08 | 6316 | @end ifset |
2e13b764 | 6317 | |
d190d046 HPN |
6318 | @node Warning |
6319 | @section @code{.warning "@var{string}"} | |
6320 | @cindex warning directive | |
6321 | Similar to the directive @code{.error} | |
6322 | (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning. | |
6323 | ||
c91d2e08 NC |
6324 | @node Weak |
6325 | @section @code{.weak @var{names}} | |
2e13b764 | 6326 | |
c1253627 | 6327 | @cindex @code{weak} directive |
a349d9dd | 6328 | This directive sets the weak attribute on the comma separated list of symbol |
c91d2e08 | 6329 | @code{names}. If the symbols do not already exist, they will be created. |
c87db184 | 6330 | |
977cdf5a NC |
6331 | On COFF targets other than PE, weak symbols are a GNU extension. This |
6332 | directive sets the weak attribute on the comma separated list of symbol | |
c87db184 CF |
6333 | @code{names}. If the symbols do not already exist, they will be created. |
6334 | ||
977cdf5a NC |
6335 | On the PE target, weak symbols are supported natively as weak aliases. |
6336 | When a weak symbol is created that is not an alias, GAS creates an | |
6337 | alternate symbol to hold the default value. | |
2e13b764 | 6338 | |
06e77878 AO |
6339 | @node Weakref |
6340 | @section @code{.weakref @var{alias}, @var{target}} | |
6341 | ||
6342 | @cindex @code{weakref} directive | |
6343 | This directive creates an alias to the target symbol that enables the symbol to | |
6344 | be referenced with weak-symbol semantics, but without actually making it weak. | |
6345 | If direct references or definitions of the symbol are present, then the symbol | |
6346 | will not be weak, but if all references to it are through weak references, the | |
6347 | symbol will be marked as weak in the symbol table. | |
6348 | ||
6349 | The effect is equivalent to moving all references to the alias to a separate | |
6350 | assembly source file, renaming the alias to the symbol in it, declaring the | |
6351 | symbol as weak there, and running a reloadable link to merge the object files | |
6352 | resulting from the assembly of the new source file and the old source file that | |
6353 | had the references to the alias removed. | |
6354 | ||
6355 | The alias itself never makes to the symbol table, and is entirely handled | |
6356 | within the assembler. | |
6357 | ||
252b5132 RH |
6358 | @node Word |
6359 | @section @code{.word @var{expressions}} | |
6360 | ||
6361 | @cindex @code{word} directive | |
6362 | This directive expects zero or more @var{expressions}, of any section, | |
6363 | separated by commas. | |
6364 | @ifclear GENERIC | |
6365 | @ifset W32 | |
a4fb0134 | 6366 | For each expression, @command{@value{AS}} emits a 32-bit number. |
252b5132 RH |
6367 | @end ifset |
6368 | @ifset W16 | |
a4fb0134 | 6369 | For each expression, @command{@value{AS}} emits a 16-bit number. |
252b5132 RH |
6370 | @end ifset |
6371 | @end ifclear | |
6372 | @ifset GENERIC | |
6373 | ||
6374 | The size of the number emitted, and its byte order, | |
6375 | depend on what target computer the assembly is for. | |
6376 | @end ifset | |
6377 | ||
6378 | @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't | |
6379 | @c happen---32-bit addressability, period; no long/short jumps. | |
6380 | @ifset DIFF-TBL-KLUGE | |
6381 | @cindex difference tables altered | |
6382 | @cindex altered difference tables | |
6383 | @quotation | |
6384 | @emph{Warning: Special Treatment to support Compilers} | |
6385 | @end quotation | |
6386 | ||
6387 | @ifset GENERIC | |
6388 | Machines with a 32-bit address space, but that do less than 32-bit | |
6389 | addressing, require the following special treatment. If the machine of | |
6390 | interest to you does 32-bit addressing (or doesn't require it; | |
6391 | @pxref{Machine Dependencies}), you can ignore this issue. | |
6392 | ||
6393 | @end ifset | |
6394 | In order to assemble compiler output into something that works, | |
a4fb0134 | 6395 | @command{@value{AS}} occasionally does strange things to @samp{.word} directives. |
252b5132 | 6396 | Directives of the form @samp{.word sym1-sym2} are often emitted by |
a4fb0134 | 6397 | compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a |
252b5132 | 6398 | directive of the form @samp{.word sym1-sym2}, and the difference between |
a4fb0134 | 6399 | @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}} |
252b5132 RH |
6400 | creates a @dfn{secondary jump table}, immediately before the next label. |
6401 | This secondary jump table is preceded by a short-jump to the | |
6402 | first byte after the secondary table. This short-jump prevents the flow | |
6403 | of control from accidentally falling into the new table. Inside the | |
6404 | table is a long-jump to @code{sym2}. The original @samp{.word} | |
6405 | contains @code{sym1} minus the address of the long-jump to | |
6406 | @code{sym2}. | |
6407 | ||
6408 | If there were several occurrences of @samp{.word sym1-sym2} before the | |
6409 | secondary jump table, all of them are adjusted. If there was a | |
6410 | @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a | |
6411 | long-jump to @code{sym4} is included in the secondary jump table, | |
6412 | and the @code{.word} directives are adjusted to contain @code{sym3} | |
6413 | minus the address of the long-jump to @code{sym4}; and so on, for as many | |
6414 | entries in the original jump table as necessary. | |
6415 | ||
6416 | @ifset INTERNALS | |
a4fb0134 | 6417 | @emph{This feature may be disabled by compiling @command{@value{AS}} with the |
252b5132 RH |
6418 | @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse |
6419 | assembly language programmers. | |
6420 | @end ifset | |
6421 | @end ifset | |
6422 | @c end DIFF-TBL-KLUGE | |
6423 | ||
6424 | @node Deprecated | |
6425 | @section Deprecated Directives | |
6426 | ||
6427 | @cindex deprecated directives | |
6428 | @cindex obsolescent directives | |
6429 | One day these directives won't work. | |
6430 | They are included for compatibility with older assemblers. | |
6431 | @table @t | |
6432 | @item .abort | |
6433 | @item .line | |
6434 | @end table | |
6435 | ||
3a99f02f DJ |
6436 | @ifset ELF |
6437 | @node Object Attributes | |
6438 | @chapter Object Attributes | |
6439 | @cindex object attributes | |
6440 | ||
6441 | @command{@value{AS}} assembles source files written for a specific architecture | |
6442 | into object files for that architecture. But not all object files are alike. | |
6443 | Many architectures support incompatible variations. For instance, floating | |
6444 | point arguments might be passed in floating point registers if the object file | |
6445 | requires hardware floating point support---or floating point arguments might be | |
6446 | passed in integer registers if the object file supports processors with no | |
6447 | hardware floating point unit. Or, if two objects are built for different | |
6448 | generations of the same architecture, the combination may require the | |
6449 | newer generation at run-time. | |
6450 | ||
6451 | This information is useful during and after linking. At link time, | |
6452 | @command{@value{LD}} can warn about incompatible object files. After link | |
6453 | time, tools like @command{gdb} can use it to process the linked file | |
6454 | correctly. | |
6455 | ||
6456 | Compatibility information is recorded as a series of object attributes. Each | |
6457 | attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a | |
6458 | string, and indicates who sets the meaning of the tag. The tag is an integer, | |
6459 | and indicates what property the attribute describes. The value may be a string | |
6460 | or an integer, and indicates how the property affects this object. Missing | |
6461 | attributes are the same as attributes with a zero value or empty string value. | |
6462 | ||
6463 | Object attributes were developed as part of the ABI for the ARM Architecture. | |
6464 | The file format is documented in @cite{ELF for the ARM Architecture}. | |
6465 | ||
6466 | @menu | |
6467 | * GNU Object Attributes:: @sc{gnu} Object Attributes | |
6468 | * Defining New Object Attributes:: Defining New Object Attributes | |
6469 | @end menu | |
6470 | ||
6471 | @node GNU Object Attributes | |
6472 | @section @sc{gnu} Object Attributes | |
6473 | ||
6474 | The @code{.gnu_attribute} directive records an object attribute | |
6475 | with vendor @samp{gnu}. | |
6476 | ||
6477 | Except for @samp{Tag_compatibility}, which has both an integer and a string for | |
6478 | its value, @sc{gnu} attributes have a string value if the tag number is odd and | |
6479 | an integer value if the tag number is even. The second bit (@code{@var{tag} & | |
6480 | 2} is set for architecture-independent attributes and clear for | |
6481 | architecture-dependent ones. | |
6482 | ||
6483 | @subsection Common @sc{gnu} attributes | |
6484 | ||
6485 | These attributes are valid on all architectures. | |
6486 | ||
6487 | @table @r | |
6488 | @item Tag_compatibility (32) | |
6489 | The compatibility attribute takes an integer flag value and a vendor name. If | |
6490 | the flag value is 0, the file is compatible with other toolchains. If it is 1, | |
6491 | then the file is only compatible with the named toolchain. If it is greater | |
6492 | than 1, the file can only be processed by other toolchains under some private | |
6493 | arrangement indicated by the flag value and the vendor name. | |
6494 | @end table | |
6495 | ||
6496 | @subsection MIPS Attributes | |
6497 | ||
6498 | @table @r | |
6499 | @item Tag_GNU_MIPS_ABI_FP (4) | |
6500 | The floating-point ABI used by this object file. The value will be: | |
6501 | ||
6502 | @itemize @bullet | |
6503 | @item | |
6504 | 0 for files not affected by the floating-point ABI. | |
6505 | @item | |
6506 | 1 for files using the hardware floating-point with a standard double-precision | |
6507 | FPU. | |
6508 | @item | |
6509 | 2 for files using the hardware floating-point ABI with a single-precision FPU. | |
6510 | @item | |
6511 | 3 for files using the software floating-point ABI. | |
42554f6a TS |
6512 | @item |
6513 | 4 for files using the hardware floating-point ABI with 64-bit wide | |
6514 | double-precision floating-point registers and 32-bit wide general | |
6515 | purpose registers. | |
3a99f02f DJ |
6516 | @end itemize |
6517 | @end table | |
6518 | ||
6519 | @subsection PowerPC Attributes | |
6520 | ||
6521 | @table @r | |
6522 | @item Tag_GNU_Power_ABI_FP (4) | |
6523 | The floating-point ABI used by this object file. The value will be: | |
6524 | ||
6525 | @itemize @bullet | |
6526 | @item | |
6527 | 0 for files not affected by the floating-point ABI. | |
6528 | @item | |
3c7b9897 | 6529 | 1 for files using double-precision hardware floating-point ABI. |
3a99f02f DJ |
6530 | @item |
6531 | 2 for files using the software floating-point ABI. | |
3c7b9897 AM |
6532 | @item |
6533 | 3 for files using single-precision hardware floating-point ABI. | |
3a99f02f DJ |
6534 | @end itemize |
6535 | ||
6536 | @item Tag_GNU_Power_ABI_Vector (8) | |
6537 | The vector ABI used by this object file. The value will be: | |
6538 | ||
6539 | @itemize @bullet | |
6540 | @item | |
6541 | 0 for files not affected by the vector ABI. | |
6542 | @item | |
6543 | 1 for files using general purpose registers to pass vectors. | |
6544 | @item | |
6545 | 2 for files using AltiVec registers to pass vectors. | |
6546 | @item | |
6547 | 3 for files using SPE registers to pass vectors. | |
6548 | @end itemize | |
6549 | @end table | |
6550 | ||
6551 | @node Defining New Object Attributes | |
6552 | @section Defining New Object Attributes | |
6553 | ||
6554 | If you want to define a new @sc{gnu} object attribute, here are the places you | |
6555 | will need to modify. New attributes should be discussed on the @samp{binutils} | |
6556 | mailing list. | |
6557 | ||
6558 | @itemize @bullet | |
6559 | @item | |
6560 | This manual, which is the official register of attributes. | |
6561 | @item | |
6562 | The header for your architecture @file{include/elf}, to define the tag. | |
6563 | @item | |
6564 | The @file{bfd} support file for your architecture, to merge the attribute | |
6565 | and issue any appropriate link warnings. | |
6566 | @item | |
6567 | Test cases in @file{ld/testsuite} for merging and link warnings. | |
6568 | @item | |
6569 | @file{binutils/readelf.c} to display your attribute. | |
6570 | @item | |
6571 | GCC, if you want the compiler to mark the attribute automatically. | |
6572 | @end itemize | |
6573 | ||
6574 | @end ifset | |
6575 | ||
252b5132 RH |
6576 | @ifset GENERIC |
6577 | @node Machine Dependencies | |
6578 | @chapter Machine Dependent Features | |
6579 | ||
6580 | @cindex machine dependencies | |
6581 | The machine instruction sets are (almost by definition) different on | |
a4fb0134 SC |
6582 | each machine where @command{@value{AS}} runs. Floating point representations |
6583 | vary as well, and @command{@value{AS}} often supports a few additional | |
252b5132 RH |
6584 | directives or command-line options for compatibility with other |
6585 | assemblers on a particular platform. Finally, some versions of | |
a4fb0134 | 6586 | @command{@value{AS}} support special pseudo-instructions for branch |
252b5132 RH |
6587 | optimization. |
6588 | ||
6589 | This chapter discusses most of these differences, though it does not | |
6590 | include details on any machine's instruction set. For details on that | |
6591 | subject, see the hardware manufacturer's manual. | |
6592 | ||
6593 | @menu | |
625e1353 RH |
6594 | @ifset ALPHA |
6595 | * Alpha-Dependent:: Alpha Dependent Features | |
6596 | @end ifset | |
252b5132 RH |
6597 | @ifset ARC |
6598 | * ARC-Dependent:: ARC Dependent Features | |
6599 | @end ifset | |
6600 | @ifset ARM | |
6601 | * ARM-Dependent:: ARM Dependent Features | |
6602 | @end ifset | |
8473f7a4 DC |
6603 | @ifset AVR |
6604 | * AVR-Dependent:: AVR Dependent Features | |
6605 | @end ifset | |
07c1b327 CM |
6606 | @ifset BFIN |
6607 | * BFIN-Dependent:: BFIN Dependent Features | |
6608 | @end ifset | |
3d3d428f NC |
6609 | @ifset CR16 |
6610 | * CR16-Dependent:: CR16 Dependent Features | |
6611 | @end ifset | |
8bf549a8 | 6612 | @ifset CRIS |
328eb32e HPN |
6613 | * CRIS-Dependent:: CRIS Dependent Features |
6614 | @end ifset | |
252b5132 RH |
6615 | @ifset D10V |
6616 | * D10V-Dependent:: D10V Dependent Features | |
6617 | @end ifset | |
6618 | @ifset D30V | |
6619 | * D30V-Dependent:: D30V Dependent Features | |
6620 | @end ifset | |
6621 | @ifset H8/300 | |
c2dcd04e | 6622 | * H8/300-Dependent:: Renesas H8/300 Dependent Features |
252b5132 | 6623 | @end ifset |
252b5132 RH |
6624 | @ifset HPPA |
6625 | * HPPA-Dependent:: HPPA Dependent Features | |
6626 | @end ifset | |
5b93d8bb AM |
6627 | @ifset I370 |
6628 | * ESA/390-Dependent:: IBM ESA/390 Dependent Features | |
6629 | @end ifset | |
252b5132 | 6630 | @ifset I80386 |
55b62671 | 6631 | * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features |
252b5132 | 6632 | @end ifset |
e3308d0d JE |
6633 | @ifset I860 |
6634 | * i860-Dependent:: Intel 80860 Dependent Features | |
6635 | @end ifset | |
252b5132 RH |
6636 | @ifset I960 |
6637 | * i960-Dependent:: Intel 80960 Dependent Features | |
6638 | @end ifset | |
5cb53c21 L |
6639 | @ifset IA64 |
6640 | * IA-64-Dependent:: Intel IA-64 Dependent Features | |
6641 | @end ifset | |
a40cbfa3 NC |
6642 | @ifset IP2K |
6643 | * IP2K-Dependent:: IP2K Dependent Features | |
6644 | @end ifset | |
49f58d10 JB |
6645 | @ifset M32C |
6646 | * M32C-Dependent:: M32C Dependent Features | |
6647 | @end ifset | |
ec694b89 NC |
6648 | @ifset M32R |
6649 | * M32R-Dependent:: M32R Dependent Features | |
6650 | @end ifset | |
252b5132 RH |
6651 | @ifset M680X0 |
6652 | * M68K-Dependent:: M680x0 Dependent Features | |
6653 | @end ifset | |
60bcf0fa NC |
6654 | @ifset M68HC11 |
6655 | * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features | |
6656 | @end ifset | |
252b5132 RH |
6657 | @ifset MIPS |
6658 | * MIPS-Dependent:: MIPS Dependent Features | |
6659 | @end ifset | |
3c3bdf30 NC |
6660 | @ifset MMIX |
6661 | * MMIX-Dependent:: MMIX Dependent Features | |
6662 | @end ifset | |
2469cfa2 NC |
6663 | @ifset MSP430 |
6664 | * MSP430-Dependent:: MSP430 Dependent Features | |
6665 | @end ifset | |
252b5132 | 6666 | @ifset SH |
ef230218 JR |
6667 | * SH-Dependent:: Renesas / SuperH SH Dependent Features |
6668 | * SH64-Dependent:: SuperH SH64 Dependent Features | |
252b5132 | 6669 | @end ifset |
e135f41b NC |
6670 | @ifset PDP11 |
6671 | * PDP-11-Dependent:: PDP-11 Dependent Features | |
6672 | @end ifset | |
041dd5a9 ILT |
6673 | @ifset PJ |
6674 | * PJ-Dependent:: picoJava Dependent Features | |
6675 | @end ifset | |
418c1742 MG |
6676 | @ifset PPC |
6677 | * PPC-Dependent:: PowerPC Dependent Features | |
6678 | @end ifset | |
252b5132 RH |
6679 | @ifset SPARC |
6680 | * Sparc-Dependent:: SPARC Dependent Features | |
6681 | @end ifset | |
39bec121 TW |
6682 | @ifset TIC54X |
6683 | * TIC54X-Dependent:: TI TMS320C54x Dependent Features | |
6684 | @end ifset | |
252b5132 RH |
6685 | @ifset V850 |
6686 | * V850-Dependent:: V850 Dependent Features | |
6687 | @end ifset | |
e0001a05 NC |
6688 | @ifset XTENSA |
6689 | * Xtensa-Dependent:: Xtensa Dependent Features | |
6690 | @end ifset | |
3c9b82ba NC |
6691 | @ifset Z80 |
6692 | * Z80-Dependent:: Z80 Dependent Features | |
6693 | @end ifset | |
252b5132 RH |
6694 | @ifset Z8000 |
6695 | * Z8000-Dependent:: Z8000 Dependent Features | |
6696 | @end ifset | |
6697 | @ifset VAX | |
6698 | * Vax-Dependent:: VAX Dependent Features | |
6699 | @end ifset | |
6700 | @end menu | |
6701 | ||
6702 | @lowersections | |
6703 | @end ifset | |
6704 | ||
6705 | @c The following major nodes are *sections* in the GENERIC version, *chapters* | |
6706 | @c in single-cpu versions. This is mainly achieved by @lowersections. There is a | |
6707 | @c peculiarity: to preserve cross-references, there must be a node called | |
6708 | @c "Machine Dependencies". Hence the conditional nodenames in each | |
6709 | @c major node below. Node defaulting in makeinfo requires adjacency of | |
6710 | @c node and sectioning commands; hence the repetition of @chapter BLAH | |
6711 | @c in both conditional blocks. | |
6712 | ||
625e1353 RH |
6713 | @ifset ALPHA |
6714 | @include c-alpha.texi | |
6715 | @end ifset | |
6716 | ||
6717 | @ifset ARC | |
6718 | @include c-arc.texi | |
6719 | @end ifset | |
6720 | ||
252b5132 RH |
6721 | @ifset ARM |
6722 | @include c-arm.texi | |
6723 | @end ifset | |
6724 | ||
8473f7a4 DC |
6725 | @ifset AVR |
6726 | @include c-avr.texi | |
6727 | @end ifset | |
6728 | ||
07c1b327 CM |
6729 | @ifset BFIN |
6730 | @include c-bfin.texi | |
6731 | @end ifset | |
6732 | ||
3d3d428f NC |
6733 | @ifset CR16 |
6734 | @include c-cr16.texi | |
6735 | @end ifset | |
6736 | ||
328eb32e HPN |
6737 | @ifset CRIS |
6738 | @include c-cris.texi | |
6739 | @end ifset | |
6740 | ||
c2dcd04e | 6741 | @ifset Renesas-all |
252b5132 RH |
6742 | @ifclear GENERIC |
6743 | @node Machine Dependencies | |
6744 | @chapter Machine Dependent Features | |
6745 | ||
c2dcd04e | 6746 | The machine instruction sets are different on each Renesas chip family, |
252b5132 | 6747 | and there are also some syntax differences among the families. This |
a4fb0134 | 6748 | chapter describes the specific @command{@value{AS}} features for each |
252b5132 RH |
6749 | family. |
6750 | ||
6751 | @menu | |
c2dcd04e | 6752 | * H8/300-Dependent:: Renesas H8/300 Dependent Features |
c2dcd04e | 6753 | * SH-Dependent:: Renesas SH Dependent Features |
252b5132 RH |
6754 | @end menu |
6755 | @lowersections | |
6756 | @end ifclear | |
6757 | @end ifset | |
6758 | ||
6759 | @ifset D10V | |
6760 | @include c-d10v.texi | |
6761 | @end ifset | |
6762 | ||
6763 | @ifset D30V | |
6764 | @include c-d30v.texi | |
6765 | @end ifset | |
6766 | ||
6767 | @ifset H8/300 | |
6768 | @include c-h8300.texi | |
6769 | @end ifset | |
6770 | ||
252b5132 RH |
6771 | @ifset HPPA |
6772 | @include c-hppa.texi | |
6773 | @end ifset | |
6774 | ||
5b93d8bb AM |
6775 | @ifset I370 |
6776 | @include c-i370.texi | |
6777 | @end ifset | |
6778 | ||
252b5132 RH |
6779 | @ifset I80386 |
6780 | @include c-i386.texi | |
6781 | @end ifset | |
6782 | ||
e3308d0d JE |
6783 | @ifset I860 |
6784 | @include c-i860.texi | |
6785 | @end ifset | |
6786 | ||
252b5132 RH |
6787 | @ifset I960 |
6788 | @include c-i960.texi | |
6789 | @end ifset | |
6790 | ||
9e32ca89 NC |
6791 | @ifset IA64 |
6792 | @include c-ia64.texi | |
6793 | @end ifset | |
6794 | ||
a40cbfa3 NC |
6795 | @ifset IP2K |
6796 | @include c-ip2k.texi | |
6797 | @end ifset | |
6798 | ||
49f58d10 JB |
6799 | @ifset M32C |
6800 | @include c-m32c.texi | |
6801 | @end ifset | |
6802 | ||
ec694b89 NC |
6803 | @ifset M32R |
6804 | @include c-m32r.texi | |
6805 | @end ifset | |
252b5132 RH |
6806 | |
6807 | @ifset M680X0 | |
6808 | @include c-m68k.texi | |
6809 | @end ifset | |
6810 | ||
60bcf0fa NC |
6811 | @ifset M68HC11 |
6812 | @include c-m68hc11.texi | |
6813 | @end ifset | |
6814 | ||
252b5132 RH |
6815 | @ifset MIPS |
6816 | @include c-mips.texi | |
6817 | @end ifset | |
6818 | ||
3c3bdf30 NC |
6819 | @ifset MMIX |
6820 | @include c-mmix.texi | |
6821 | @end ifset | |
6822 | ||
2469cfa2 NC |
6823 | @ifset MSP430 |
6824 | @include c-msp430.texi | |
6825 | @end ifset | |
6826 | ||
252b5132 RH |
6827 | @ifset NS32K |
6828 | @include c-ns32k.texi | |
6829 | @end ifset | |
6830 | ||
e135f41b NC |
6831 | @ifset PDP11 |
6832 | @include c-pdp11.texi | |
6833 | @end ifset | |
6834 | ||
041dd5a9 ILT |
6835 | @ifset PJ |
6836 | @include c-pj.texi | |
6837 | @end ifset | |
6838 | ||
418c1742 MG |
6839 | @ifset PPC |
6840 | @include c-ppc.texi | |
6841 | @end ifset | |
6842 | ||
252b5132 RH |
6843 | @ifset SH |
6844 | @include c-sh.texi | |
324bfcf3 | 6845 | @include c-sh64.texi |
252b5132 RH |
6846 | @end ifset |
6847 | ||
6848 | @ifset SPARC | |
6849 | @include c-sparc.texi | |
6850 | @end ifset | |
6851 | ||
39bec121 TW |
6852 | @ifset TIC54X |
6853 | @include c-tic54x.texi | |
6854 | @end ifset | |
6855 | ||
3c9b82ba NC |
6856 | @ifset Z80 |
6857 | @include c-z80.texi | |
6858 | @end ifset | |
6859 | ||
252b5132 RH |
6860 | @ifset Z8000 |
6861 | @include c-z8k.texi | |
6862 | @end ifset | |
6863 | ||
6864 | @ifset VAX | |
6865 | @include c-vax.texi | |
6866 | @end ifset | |
6867 | ||
6868 | @ifset V850 | |
6869 | @include c-v850.texi | |
6870 | @end ifset | |
6871 | ||
e0001a05 NC |
6872 | @ifset XTENSA |
6873 | @include c-xtensa.texi | |
6874 | @end ifset | |
6875 | ||
252b5132 RH |
6876 | @ifset GENERIC |
6877 | @c reverse effect of @down at top of generic Machine-Dep chapter | |
6878 | @raisesections | |
6879 | @end ifset | |
6880 | ||
6881 | @node Reporting Bugs | |
6882 | @chapter Reporting Bugs | |
6883 | @cindex bugs in assembler | |
6884 | @cindex reporting bugs in assembler | |
6885 | ||
a4fb0134 | 6886 | Your bug reports play an essential role in making @command{@value{AS}} reliable. |
252b5132 RH |
6887 | |
6888 | Reporting a bug may help you by bringing a solution to your problem, or it may | |
6889 | not. But in any case the principal function of a bug report is to help the | |
a4fb0134 SC |
6890 | entire community by making the next version of @command{@value{AS}} work better. |
6891 | Bug reports are your contribution to the maintenance of @command{@value{AS}}. | |
252b5132 RH |
6892 | |
6893 | In order for a bug report to serve its purpose, you must include the | |
6894 | information that enables us to fix the bug. | |
6895 | ||
6896 | @menu | |
6897 | * Bug Criteria:: Have you found a bug? | |
6898 | * Bug Reporting:: How to report bugs | |
6899 | @end menu | |
6900 | ||
6901 | @node Bug Criteria | |
c1253627 | 6902 | @section Have You Found a Bug? |
252b5132 RH |
6903 | @cindex bug criteria |
6904 | ||
6905 | If you are not sure whether you have found a bug, here are some guidelines: | |
6906 | ||
6907 | @itemize @bullet | |
6908 | @cindex fatal signal | |
6909 | @cindex assembler crash | |
6910 | @cindex crash of assembler | |
6911 | @item | |
6912 | If the assembler gets a fatal signal, for any input whatever, that is a | |
a4fb0134 | 6913 | @command{@value{AS}} bug. Reliable assemblers never crash. |
252b5132 RH |
6914 | |
6915 | @cindex error on valid input | |
6916 | @item | |
a4fb0134 | 6917 | If @command{@value{AS}} produces an error message for valid input, that is a bug. |
252b5132 RH |
6918 | |
6919 | @cindex invalid input | |
6920 | @item | |
a4fb0134 | 6921 | If @command{@value{AS}} does not produce an error message for invalid input, that |
252b5132 RH |
6922 | is a bug. However, you should note that your idea of ``invalid input'' might |
6923 | be our idea of ``an extension'' or ``support for traditional practice''. | |
6924 | ||
6925 | @item | |
6926 | If you are an experienced user of assemblers, your suggestions for improvement | |
a4fb0134 | 6927 | of @command{@value{AS}} are welcome in any case. |
252b5132 RH |
6928 | @end itemize |
6929 | ||
6930 | @node Bug Reporting | |
c1253627 | 6931 | @section How to Report Bugs |
252b5132 RH |
6932 | @cindex bug reports |
6933 | @cindex assembler bugs, reporting | |
6934 | ||
6935 | A number of companies and individuals offer support for @sc{gnu} products. If | |
a4fb0134 | 6936 | you obtained @command{@value{AS}} from a support organization, we recommend you |
252b5132 RH |
6937 | contact that organization first. |
6938 | ||
6939 | You can find contact information for many support companies and | |
6940 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs | |
6941 | distribution. | |
6942 | ||
ad22bfe8 | 6943 | @ifset BUGURL |
a4fb0134 | 6944 | In any event, we also recommend that you send bug reports for @command{@value{AS}} |
ad22bfe8 JM |
6945 | to @value{BUGURL}. |
6946 | @end ifset | |
252b5132 RH |
6947 | |
6948 | The fundamental principle of reporting bugs usefully is this: | |
6949 | @strong{report all the facts}. If you are not sure whether to state a | |
6950 | fact or leave it out, state it! | |
6951 | ||
6952 | Often people omit facts because they think they know what causes the problem | |
6953 | and assume that some details do not matter. Thus, you might assume that the | |
6954 | name of a symbol you use in an example does not matter. Well, probably it does | |
6955 | not, but one cannot be sure. Perhaps the bug is a stray memory reference which | |
6956 | happens to fetch from the location where that name is stored in memory; | |
6957 | perhaps, if the name were different, the contents of that location would fool | |
6958 | the assembler into doing the right thing despite the bug. Play it safe and | |
6959 | give a specific, complete example. That is the easiest thing for you to do, | |
6960 | and the most helpful. | |
6961 | ||
6962 | Keep in mind that the purpose of a bug report is to enable us to fix the bug if | |
6963 | it is new to us. Therefore, always write your bug reports on the assumption | |
6964 | that the bug has not been reported previously. | |
6965 | ||
6966 | Sometimes people give a few sketchy facts and ask, ``Does this ring a | |
c1253627 NC |
6967 | bell?'' This cannot help us fix a bug, so it is basically useless. We |
6968 | respond by asking for enough details to enable us to investigate. | |
6969 | You might as well expedite matters by sending them to begin with. | |
252b5132 RH |
6970 | |
6971 | To enable us to fix the bug, you should include all these things: | |
6972 | ||
6973 | @itemize @bullet | |
6974 | @item | |
a4fb0134 | 6975 | The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start |
252b5132 RH |
6976 | it with the @samp{--version} argument. |
6977 | ||
6978 | Without this, we will not know whether there is any point in looking for | |
a4fb0134 | 6979 | the bug in the current version of @command{@value{AS}}. |
252b5132 RH |
6980 | |
6981 | @item | |
a4fb0134 | 6982 | Any patches you may have applied to the @command{@value{AS}} source. |
252b5132 RH |
6983 | |
6984 | @item | |
6985 | The type of machine you are using, and the operating system name and | |
6986 | version number. | |
6987 | ||
6988 | @item | |
a4fb0134 | 6989 | What compiler (and its version) was used to compile @command{@value{AS}}---e.g. |
252b5132 RH |
6990 | ``@code{gcc-2.7}''. |
6991 | ||
6992 | @item | |
6993 | The command arguments you gave the assembler to assemble your example and | |
6994 | observe the bug. To guarantee you will not omit something important, list them | |
6995 | all. A copy of the Makefile (or the output from make) is sufficient. | |
6996 | ||
6997 | If we were to try to guess the arguments, we would probably guess wrong | |
6998 | and then we might not encounter the bug. | |
6999 | ||
7000 | @item | |
7001 | A complete input file that will reproduce the bug. If the bug is observed when | |
7002 | the assembler is invoked via a compiler, send the assembler source, not the | |
7003 | high level language source. Most compilers will produce the assembler source | |
7004 | when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use | |
7005 | the options @samp{-v --save-temps}; this will save the assembler source in a | |
7006 | file with an extension of @file{.s}, and also show you exactly how | |
a4fb0134 | 7007 | @command{@value{AS}} is being run. |
252b5132 RH |
7008 | |
7009 | @item | |
7010 | A description of what behavior you observe that you believe is | |
7011 | incorrect. For example, ``It gets a fatal signal.'' | |
7012 | ||
a4fb0134 | 7013 | Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we |
252b5132 RH |
7014 | will certainly notice it. But if the bug is incorrect output, we might not |
7015 | notice unless it is glaringly wrong. You might as well not give us a chance to | |
7016 | make a mistake. | |
7017 | ||
7018 | Even if the problem you experience is a fatal signal, you should still say so | |
7019 | explicitly. Suppose something strange is going on, such as, your copy of | |
b45619c0 | 7020 | @command{@value{AS}} is out of sync, or you have encountered a bug in the C |
252b5132 RH |
7021 | library on your system. (This has happened!) Your copy might crash and ours |
7022 | would not. If you told us to expect a crash, then when ours fails to crash, we | |
7023 | would know that the bug was not happening for us. If you had not told us to | |
7024 | expect a crash, then we would not be able to draw any conclusion from our | |
7025 | observations. | |
7026 | ||
7027 | @item | |
a4fb0134 | 7028 | If you wish to suggest changes to the @command{@value{AS}} source, send us context |
252b5132 RH |
7029 | diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p} |
7030 | option. Always send diffs from the old file to the new file. If you even | |
a4fb0134 | 7031 | discuss something in the @command{@value{AS}} source, refer to it by context, not |
252b5132 RH |
7032 | by line number. |
7033 | ||
7034 | The line numbers in our development sources will not match those in your | |
7035 | sources. Your line numbers would convey no useful information to us. | |
7036 | @end itemize | |
7037 | ||
7038 | Here are some things that are not necessary: | |
7039 | ||
7040 | @itemize @bullet | |
7041 | @item | |
7042 | A description of the envelope of the bug. | |
7043 | ||
7044 | Often people who encounter a bug spend a lot of time investigating | |
7045 | which changes to the input file will make the bug go away and which | |
7046 | changes will not affect it. | |
7047 | ||
7048 | This is often time consuming and not very useful, because the way we | |
7049 | will find the bug is by running a single example under the debugger | |
7050 | with breakpoints, not by pure deduction from a series of examples. | |
7051 | We recommend that you save your time for something else. | |
7052 | ||
7053 | Of course, if you can find a simpler example to report @emph{instead} | |
7054 | of the original one, that is a convenience for us. Errors in the | |
7055 | output will be easier to spot, running under the debugger will take | |
7056 | less time, and so on. | |
7057 | ||
7058 | However, simplification is not vital; if you do not want to do this, | |
7059 | report the bug anyway and send us the entire test case you used. | |
7060 | ||
7061 | @item | |
7062 | A patch for the bug. | |
7063 | ||
7064 | A patch for the bug does help us if it is a good one. But do not omit | |
7065 | the necessary information, such as the test case, on the assumption that | |
7066 | a patch is all we need. We might see problems with your patch and decide | |
7067 | to fix the problem another way, or we might not understand it at all. | |
7068 | ||
a4fb0134 | 7069 | Sometimes with a program as complicated as @command{@value{AS}} it is very hard to |
252b5132 RH |
7070 | construct an example that will make the program follow a certain path through |
7071 | the code. If you do not send us the example, we will not be able to construct | |
7072 | one, so we will not be able to verify that the bug is fixed. | |
7073 | ||
7074 | And if we cannot understand what bug you are trying to fix, or why your | |
7075 | patch should be an improvement, we will not install it. A test case will | |
7076 | help us to understand. | |
7077 | ||
7078 | @item | |
7079 | A guess about what the bug is or what it depends on. | |
7080 | ||
7081 | Such guesses are usually wrong. Even we cannot guess right about such | |
7082 | things without first using the debugger to find the facts. | |
7083 | @end itemize | |
7084 | ||
7085 | @node Acknowledgements | |
7086 | @chapter Acknowledgements | |
7087 | ||
653cfe85 | 7088 | If you have contributed to GAS and your name isn't listed here, |
252b5132 RH |
7089 | it is not meant as a slight. We just don't know about it. Send mail to the |
7090 | maintainer, and we'll correct the situation. Currently | |
7091 | @c (January 1994), | |
7092 | the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}). | |
7093 | ||
7094 | Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any | |
7095 | more details?} | |
7096 | ||
7097 | Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug | |
7098 | information and the 68k series machines, most of the preprocessing pass, and | |
7099 | extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}. | |
7100 | ||
7101 | K. Richard Pixley maintained GAS for a while, adding various enhancements and | |
7102 | many bug fixes, including merging support for several processors, breaking GAS | |
7103 | up to handle multiple object file format back ends (including heavy rewrite, | |
7104 | testing, an integration of the coff and b.out back ends), adding configuration | |
7105 | including heavy testing and verification of cross assemblers and file splits | |
7106 | and renaming, converted GAS to strictly ANSI C including full prototypes, added | |
7107 | support for m680[34]0 and cpu32, did considerable work on i960 including a COFF | |
7108 | port (including considerable amounts of reverse engineering), a SPARC opcode | |
7109 | file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know'' | |
7110 | assertions and made them work, much other reorganization, cleanup, and lint. | |
7111 | ||
7112 | Ken Raeburn wrote the high-level BFD interface code to replace most of the code | |
7113 | in format-specific I/O modules. | |
7114 | ||
7115 | The original VMS support was contributed by David L. Kashtan. Eric Youngdale | |
7116 | has done much work with it since. | |
7117 | ||
7118 | The Intel 80386 machine description was written by Eliot Dresselhaus. | |
7119 | ||
7120 | Minh Tran-Le at IntelliCorp contributed some AIX 386 support. | |
7121 | ||
7122 | The Motorola 88k machine description was contributed by Devon Bowen of Buffalo | |
7123 | University and Torbjorn Granlund of the Swedish Institute of Computer Science. | |
7124 | ||
7125 | Keith Knowles at the Open Software Foundation wrote the original MIPS back end | |
7126 | (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support | |
7127 | (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to | |
7128 | support a.out format. | |
7129 | ||
7be1c489 AM |
7130 | Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k, |
7131 | tc-h8300), and IEEE 695 object file format (obj-ieee), was written by | |
252b5132 RH |
7132 | Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to |
7133 | use BFD for some low-level operations, for use with the H8/300 and AMD 29k | |
7134 | targets. | |
7135 | ||
7136 | John Gilmore built the AMD 29000 support, added @code{.include} support, and | |
7137 | simplified the configuration of which versions accept which directives. He | |
7138 | updated the 68k machine description so that Motorola's opcodes always produced | |
c1253627 | 7139 | fixed-size instructions (e.g., @code{jsr}), while synthetic instructions |
252b5132 RH |
7140 | remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested |
7141 | cross-compilation support, and one bug in relaxation that took a week and | |
7142 | required the proverbial one-bit fix. | |
7143 | ||
7144 | Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the | |
7145 | 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix), | |
7146 | added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and | |
7147 | PowerPC assembler, and made a few other minor patches. | |
7148 | ||
653cfe85 | 7149 | Steve Chamberlain made GAS able to generate listings. |
252b5132 RH |
7150 | |
7151 | Hewlett-Packard contributed support for the HP9000/300. | |
7152 | ||
7153 | Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM) | |
7154 | along with a fairly extensive HPPA testsuite (for both SOM and ELF object | |
7155 | formats). This work was supported by both the Center for Software Science at | |
7156 | the University of Utah and Cygnus Support. | |
7157 | ||
7158 | Support for ELF format files has been worked on by Mark Eichin of Cygnus | |
7159 | Support (original, incomplete implementation for SPARC), Pete Hoogenboom and | |
7160 | Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open | |
7161 | Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc, | |
7162 | and some initial 64-bit support). | |
7163 | ||
c1253627 | 7164 | Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture. |
5b93d8bb | 7165 | |
252b5132 RH |
7166 | Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD |
7167 | support for openVMS/Alpha. | |
7168 | ||
39bec121 TW |
7169 | Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic* |
7170 | flavors. | |
7171 | ||
e0001a05 | 7172 | David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica, |
b45619c0 | 7173 | Inc.@: added support for Xtensa processors. |
e0001a05 | 7174 | |
252b5132 RH |
7175 | Several engineers at Cygnus Support have also provided many small bug fixes and |
7176 | configuration enhancements. | |
7177 | ||
7178 | Many others have contributed large or small bugfixes and enhancements. If | |
7179 | you have contributed significant work and are not mentioned on this list, and | |
7180 | want to be, let us know. Some of the history has been lost; we are not | |
7181 | intentionally leaving anyone out. | |
7182 | ||
c1253627 | 7183 | @include fdl.texi |
cf055d54 | 7184 | |
370b66a1 CD |
7185 | @node AS Index |
7186 | @unnumbered AS Index | |
252b5132 RH |
7187 | |
7188 | @printindex cp | |
7189 | ||
252b5132 RH |
7190 | @bye |
7191 | @c Local Variables: | |
7192 | @c fill-column: 79 | |
7193 | @c End: |