1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright (C) 1991-2021 Free Software Foundation, Inc.
3 @c UPDATE!! On future updates--
4 @c (1) check for new machine-dep cmdline options in
5 @c md_parse_option definitions in config/tc-*.c
6 @c (2) for platform-specific directives, examine md_pseudo_op
8 @c (3) for object-format specific directives, examine obj_pseudo_op
10 @c (4) portable directives in potable[] in read.c
14 @macro gcctabopt{body}
17 @c defaults, config file may override:
22 @include asconfig.texi
27 @c common OR combinations of conditions
53 @set abnormal-separator
57 @settitle Using @value{AS}
60 @settitle Using @value{AS} (@value{TARGET})
62 @setchapternewpage odd
67 @c WARE! Some of the machine-dependent sections contain tables of machine
68 @c instructions. Except in multi-column format, these tables look silly.
69 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
70 @c the multi-col format is faked within @example sections.
72 @c Again unfortunately, the natural size that fits on a page, for these tables,
73 @c is different depending on whether or not smallbook is turned on.
74 @c This matters, because of order: text flow switches columns at each page
77 @c The format faked in this source works reasonably well for smallbook,
78 @c not well for the default large-page format. This manual expects that if you
79 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
80 @c tables in question. You can turn on one without the other at your
81 @c discretion, of course.
84 @c the insn tables look just as silly in info files regardless of smallbook,
85 @c might as well show 'em anyways.
89 @dircategory Software development
91 * As: (as). The GNU assembler.
92 * Gas: (as). The GNU assembler.
100 This file documents the GNU Assembler "@value{AS}".
102 @c man begin COPYRIGHT
103 Copyright @copyright{} 1991-2021 Free Software Foundation, Inc.
105 Permission is granted to copy, distribute and/or modify this document
106 under the terms of the GNU Free Documentation License, Version 1.3
107 or any later version published by the Free Software Foundation;
108 with no Invariant Sections, with no Front-Cover Texts, and with no
109 Back-Cover Texts. A copy of the license is included in the
110 section entitled ``GNU Free Documentation License''.
116 @title Using @value{AS}
117 @subtitle The @sc{gnu} Assembler
119 @subtitle for the @value{TARGET} family
121 @ifset VERSION_PACKAGE
123 @subtitle @value{VERSION_PACKAGE}
126 @subtitle Version @value{VERSION}
129 The Free Software Foundation Inc.@: thanks The Nice Computer
130 Company of Australia for loaning Dean Elsner to write the
131 first (Vax) version of @command{as} for Project @sc{gnu}.
132 The proprietors, management and staff of TNCCA thank FSF for
133 distracting the boss while they got some work
136 @author Dean Elsner, Jay Fenlason & friends
140 \hfill {\it Using {\tt @value{AS}}}\par
141 \hfill Edited by Cygnus Support\par
143 %"boxit" macro for figures:
144 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
145 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
146 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
147 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
148 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
151 @vskip 0pt plus 1filll
152 Copyright @copyright{} 1991-2021 Free Software Foundation, Inc.
154 Permission is granted to copy, distribute and/or modify this document
155 under the terms of the GNU Free Documentation License, Version 1.3
156 or any later version published by the Free Software Foundation;
157 with no Invariant Sections, with no Front-Cover Texts, and with no
158 Back-Cover Texts. A copy of the license is included in the
159 section entitled ``GNU Free Documentation License''.
166 @top Using @value{AS}
168 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}}
169 @ifset VERSION_PACKAGE
170 @value{VERSION_PACKAGE}
172 version @value{VERSION}.
174 This version of the file describes @command{@value{AS}} configured to generate
175 code for @value{TARGET} architectures.
178 This document is distributed under the terms of the GNU Free
179 Documentation License. A copy of the license is included in the
180 section entitled ``GNU Free Documentation License''.
183 * Overview:: Overview
184 * Invoking:: Command-Line Options
186 * Sections:: Sections and Relocation
188 * Expressions:: Expressions
189 * Pseudo Ops:: Assembler Directives
191 * Object Attributes:: Object Attributes
193 * Machine Dependencies:: Machine Dependent Features
194 * Reporting Bugs:: Reporting Bugs
195 * Acknowledgements:: Who Did What
196 * GNU Free Documentation License:: GNU Free Documentation License
197 * AS Index:: AS Index
204 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
206 This version of the manual describes @command{@value{AS}} configured to generate
207 code for @value{TARGET} architectures.
211 @cindex invocation summary
212 @cindex option summary
213 @cindex summary of options
214 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
215 see @ref{Invoking,,Command-Line Options}.
217 @c man title AS the portable GNU assembler.
221 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
225 @c We don't use deffn and friends for the following because they seem
226 @c to be limited to one line for the header.
228 @c man begin SYNOPSIS
229 @value{AS} [@b{-a}[@b{cdghlns}][=@var{file}]] [@b{--alternate}] [@b{-D}]
230 [@b{--compress-debug-sections}] [@b{--nocompress-debug-sections}]
231 [@b{--debug-prefix-map} @var{old}=@var{new}]
232 [@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}]
233 [@b{--gstabs+}] [@b{--gdwarf-<N>}] [@b{--gdwarf-sections}]
234 [@b{--gdwarf-cie-version}=@var{VERSION}]
235 [@b{--help}] [@b{-I} @var{dir}] [@b{-J}]
236 [@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}]
237 [@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}]
238 [@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}]
239 [@b{--no-pad-sections}]
240 [@b{-o} @var{objfile}] [@b{-R}]
242 [@b{-v}] [@b{-version}] [@b{--version}]
243 [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}] [@b{-w}] [@b{-x}]
244 [@b{-Z}] [@b{@@@var{FILE}}]
245 [@b{--sectname-subst}] [@b{--size-check=[error|warning]}]
246 [@b{--elf-stt-common=[no|yes]}]
247 [@b{--generate-missing-build-notes=[no|yes]}]
248 [@b{--multibyte-handling=[allow|warn|warn-sym-only]}]
249 [@b{--target-help}] [@var{target-options}]
250 [@b{--}|@var{files} @dots{}]
253 @c Target dependent options are listed below. Keep the list sorted.
254 @c Add an empty line for separation.
258 @emph{Target AArch64 options:}
260 [@b{-mabi}=@var{ABI}]
264 @emph{Target Alpha options:}
266 [@b{-mdebug} | @b{-no-mdebug}]
267 [@b{-replace} | @b{-noreplace}]
268 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
269 [@b{-F}] [@b{-32addr}]
273 @emph{Target ARC options:}
274 [@b{-mcpu=@var{cpu}}]
275 [@b{-mA6}|@b{-mARC600}|@b{-mARC601}|@b{-mA7}|@b{-mARC700}|@b{-mEM}|@b{-mHS}]
282 @emph{Target ARM options:}
283 @c Don't document the deprecated options
284 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
285 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
286 [@b{-mfpu}=@var{floating-point-format}]
287 [@b{-mfloat-abi}=@var{abi}]
288 [@b{-meabi}=@var{ver}]
291 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
292 @b{-mapcs-reentrant}]
293 [@b{-mthumb-interwork}] [@b{-k}]
297 @emph{Target Blackfin options:}
298 [@b{-mcpu}=@var{processor}[-@var{sirevision}]]
305 @emph{Target BPF options:}
310 @emph{Target CRIS options:}
311 [@b{--underscore} | @b{--no-underscore}]
313 [@b{--emulation=criself} | @b{--emulation=crisaout}]
314 [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}]
315 @c Deprecated -- deliberately not documented.
320 @emph{Target C-SKY options:}
321 [@b{-march=@var{arch}}] [@b{-mcpu=@var{cpu}}]
322 [@b{-EL}] [@b{-mlittle-endian}] [@b{-EB}] [@b{-mbig-endian}]
323 [@b{-fpic}] [@b{-pic}]
324 [@b{-mljump}] [@b{-mno-ljump}]
325 [@b{-force2bsr}] [@b{-mforce2bsr}] [@b{-no-force2bsr}] [@b{-mno-force2bsr}]
326 [@b{-jsri2bsr}] [@b{-mjsri2bsr}] [@b{-no-jsri2bsr }] [@b{-mno-jsri2bsr}]
327 [@b{-mnolrw }] [@b{-mno-lrw}]
328 [@b{-melrw}] [@b{-mno-elrw}]
329 [@b{-mlaf }] [@b{-mliterals-after-func}]
330 [@b{-mno-laf}] [@b{-mno-literals-after-func}]
331 [@b{-mlabr}] [@b{-mliterals-after-br}]
332 [@b{-mno-labr}] [@b{-mnoliterals-after-br}]
333 [@b{-mistack}] [@b{-mno-istack}]
334 [@b{-mhard-float}] [@b{-mmp}] [@b{-mcp}] [@b{-mcache}]
335 [@b{-msecurity}] [@b{-mtrust}]
336 [@b{-mdsp}] [@b{-medsp}] [@b{-mvdsp}]
340 @emph{Target D10V options:}
345 @emph{Target D30V options:}
346 [@b{-O}|@b{-n}|@b{-N}]
350 @emph{Target EPIPHANY options:}
351 [@b{-mepiphany}|@b{-mepiphany16}]
355 @emph{Target H8/300 options:}
359 @c HPPA has no machine-dependent assembler options (yet).
363 @emph{Target i386 options:}
364 [@b{--32}|@b{--x32}|@b{--64}] [@b{-n}]
365 [@b{-march}=@var{CPU}[+@var{EXTENSION}@dots{}]] [@b{-mtune}=@var{CPU}]
369 @emph{Target IA-64 options:}
370 [@b{-mconstant-gp}|@b{-mauto-pic}]
371 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
373 [@b{-mtune=itanium1}|@b{-mtune=itanium2}]
374 [@b{-munwind-check=warning}|@b{-munwind-check=error}]
375 [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}]
376 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
380 @emph{Target IP2K options:}
381 [@b{-mip2022}|@b{-mip2022ext}]
385 @emph{Target LOONGARCH options:}
386 [@b{-fpic}|@b{-fPIC}|@b{-fno-pic}]
390 @emph{Target M32C options:}
391 [@b{-m32c}|@b{-m16c}] [-relax] [-h-tick-hex]
395 @emph{Target M32R options:}
396 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
401 @emph{Target M680X0 options:}
402 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
406 @emph{Target M68HC11 options:}
407 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}|@b{-mm9s12x}|@b{-mm9s12xg}]
408 [@b{-mshort}|@b{-mlong}]
409 [@b{-mshort-double}|@b{-mlong-double}]
410 [@b{--force-long-branches}] [@b{--short-branches}]
411 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
412 [@b{--print-opcodes}] [@b{--generate-example}]
416 @emph{Target MCORE options:}
417 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
418 [@b{-mcpu=[210|340]}]
422 @emph{Target Meta options:}
423 [@b{-mcpu=@var{cpu}}] [@b{-mfpu=@var{cpu}}] [@b{-mdsp=@var{cpu}}]
426 @emph{Target MICROBLAZE options:}
427 @c MicroBlaze has no machine-dependent assembler options.
431 @emph{Target MIPS options:}
432 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
433 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
434 [@b{-non_shared}] [@b{-xgot} [@b{-mvxworks-pic}]
435 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
436 [@b{-mfp64}] [@b{-mgp64}] [@b{-mfpxx}]
437 [@b{-modd-spreg}] [@b{-mno-odd-spreg}]
438 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
439 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
440 [@b{-mips32r3}] [@b{-mips32r5}] [@b{-mips32r6}] [@b{-mips64}] [@b{-mips64r2}]
441 [@b{-mips64r3}] [@b{-mips64r5}] [@b{-mips64r6}]
442 [@b{-construct-floats}] [@b{-no-construct-floats}]
443 [@b{-mignore-branch-isa}] [@b{-mno-ignore-branch-isa}]
444 [@b{-mnan=@var{encoding}}]
445 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
446 [@b{-mips16}] [@b{-no-mips16}]
447 [@b{-mmips16e2}] [@b{-mno-mips16e2}]
448 [@b{-mmicromips}] [@b{-mno-micromips}]
449 [@b{-msmartmips}] [@b{-mno-smartmips}]
450 [@b{-mips3d}] [@b{-no-mips3d}]
451 [@b{-mdmx}] [@b{-no-mdmx}]
452 [@b{-mdsp}] [@b{-mno-dsp}]
453 [@b{-mdspr2}] [@b{-mno-dspr2}]
454 [@b{-mdspr3}] [@b{-mno-dspr3}]
455 [@b{-mmsa}] [@b{-mno-msa}]
456 [@b{-mxpa}] [@b{-mno-xpa}]
457 [@b{-mmt}] [@b{-mno-mt}]
458 [@b{-mmcu}] [@b{-mno-mcu}]
459 [@b{-mcrc}] [@b{-mno-crc}]
460 [@b{-mginv}] [@b{-mno-ginv}]
461 [@b{-mloongson-mmi}] [@b{-mno-loongson-mmi}]
462 [@b{-mloongson-cam}] [@b{-mno-loongson-cam}]
463 [@b{-mloongson-ext}] [@b{-mno-loongson-ext}]
464 [@b{-mloongson-ext2}] [@b{-mno-loongson-ext2}]
465 [@b{-minsn32}] [@b{-mno-insn32}]
466 [@b{-mfix7000}] [@b{-mno-fix7000}]
467 [@b{-mfix-rm7000}] [@b{-mno-fix-rm7000}]
468 [@b{-mfix-vr4120}] [@b{-mno-fix-vr4120}]
469 [@b{-mfix-vr4130}] [@b{-mno-fix-vr4130}]
470 [@b{-mfix-r5900}] [@b{-mno-fix-r5900}]
471 [@b{-mdebug}] [@b{-no-mdebug}]
472 [@b{-mpdr}] [@b{-mno-pdr}]
476 @emph{Target MMIX options:}
477 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
478 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
479 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
480 [@b{--linker-allocated-gregs}]
484 @emph{Target Nios II options:}
485 [@b{-relax-all}] [@b{-relax-section}] [@b{-no-relax}]
490 @emph{Target NDS32 options:}
491 [@b{-EL}] [@b{-EB}] [@b{-O}] [@b{-Os}] [@b{-mcpu=@var{cpu}}]
492 [@b{-misa=@var{isa}}] [@b{-mabi=@var{abi}}] [@b{-mall-ext}]
493 [@b{-m[no-]16-bit}] [@b{-m[no-]perf-ext}] [@b{-m[no-]perf2-ext}]
494 [@b{-m[no-]string-ext}] [@b{-m[no-]dsp-ext}] [@b{-m[no-]mac}] [@b{-m[no-]div}]
495 [@b{-m[no-]audio-isa-ext}] [@b{-m[no-]fpu-sp-ext}] [@b{-m[no-]fpu-dp-ext}]
496 [@b{-m[no-]fpu-fma}] [@b{-mfpu-freg=@var{FREG}}] [@b{-mreduced-regs}]
497 [@b{-mfull-regs}] [@b{-m[no-]dx-regs}] [@b{-mpic}] [@b{-mno-relax}]
501 @c OpenRISC has no machine-dependent assembler options.
505 @emph{Target PDP11 options:}
506 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
507 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
508 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
512 @emph{Target picoJava options:}
517 @emph{Target PowerPC options:}
519 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|@b{-m403}|@b{-m405}|
520 @b{-m440}|@b{-m464}|@b{-m476}|@b{-m7400}|@b{-m7410}|@b{-m7450}|@b{-m7455}|@b{-m750cl}|@b{-mgekko}|
521 @b{-mbroadway}|@b{-mppc64}|@b{-m620}|@b{-me500}|@b{-e500x2}|@b{-me500mc}|@b{-me500mc64}|@b{-me5500}|
522 @b{-me6500}|@b{-mppc64bridge}|@b{-mbooke}|@b{-mpower4}|@b{-mpwr4}|@b{-mpower5}|@b{-mpwr5}|@b{-mpwr5x}|
523 @b{-mpower6}|@b{-mpwr6}|@b{-mpower7}|@b{-mpwr7}|@b{-mpower8}|@b{-mpwr8}|@b{-mpower9}|@b{-mpwr9}@b{-ma2}|
524 @b{-mcell}|@b{-mspe}|@b{-mspe2}|@b{-mtitan}|@b{-me300}|@b{-mcom}]
525 [@b{-many}] [@b{-maltivec}|@b{-mvsx}|@b{-mhtm}|@b{-mvle}]
526 [@b{-mregnames}|@b{-mno-regnames}]
527 [@b{-mrelocatable}|@b{-mrelocatable-lib}|@b{-K PIC}] [@b{-memb}]
528 [@b{-mlittle}|@b{-mlittle-endian}|@b{-le}|@b{-mbig}|@b{-mbig-endian}|@b{-be}]
529 [@b{-msolaris}|@b{-mno-solaris}]
530 [@b{-nops=@var{count}}]
534 @emph{Target PRU options:}
537 [@b{-mno-warn-regname-label}]
541 @emph{Target RISC-V options:}
542 [@b{-fpic}|@b{-fPIC}|@b{-fno-pic}]
543 [@b{-march}=@var{ISA}]
544 [@b{-mabi}=@var{ABI}]
545 [@b{-mlittle-endian}|@b{-mbig-endian}]
549 @emph{Target RL78 options:}
551 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
555 @emph{Target RX options:}
556 [@b{-mlittle-endian}|@b{-mbig-endian}]
557 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
558 [@b{-muse-conventional-section-names}]
559 [@b{-msmall-data-limit}]
562 [@b{-mint-register=@var{number}}]
563 [@b{-mgcc-abi}|@b{-mrx-abi}]
567 @emph{Target s390 options:}
568 [@b{-m31}|@b{-m64}] [@b{-mesa}|@b{-mzarch}] [@b{-march}=@var{CPU}]
569 [@b{-mregnames}|@b{-mno-regnames}]
570 [@b{-mwarn-areg-zero}]
574 @emph{Target SCORE options:}
575 [@b{-EB}][@b{-EL}][@b{-FIXDD}][@b{-NWARN}]
576 [@b{-SCORE5}][@b{-SCORE5U}][@b{-SCORE7}][@b{-SCORE3}]
577 [@b{-march=score7}][@b{-march=score3}]
578 [@b{-USE_R1}][@b{-KPIC}][@b{-O0}][@b{-G} @var{num}][@b{-V}]
582 @emph{Target SPARC options:}
583 @c The order here is important. See c-sparc.texi.
584 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Aleon}|@b{-Asparclet}|@b{-Asparclite}
585 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av8plusb}|@b{-Av8plusc}|@b{-Av8plusd}
586 @b{-Av8plusv}|@b{-Av8plusm}|@b{-Av9}|@b{-Av9a}|@b{-Av9b}|@b{-Av9c}
587 @b{-Av9d}|@b{-Av9e}|@b{-Av9v}|@b{-Av9m}|@b{-Asparc}|@b{-Asparcvis}
588 @b{-Asparcvis2}|@b{-Asparcfmaf}|@b{-Asparcima}|@b{-Asparcvis3}
589 @b{-Asparcvisr}|@b{-Asparc5}]
590 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}]|@b{-xarch=v8plusb}|@b{-xarch=v8plusc}
591 @b{-xarch=v8plusd}|@b{-xarch=v8plusv}|@b{-xarch=v8plusm}|@b{-xarch=v9}
592 @b{-xarch=v9a}|@b{-xarch=v9b}|@b{-xarch=v9c}|@b{-xarch=v9d}|@b{-xarch=v9e}
593 @b{-xarch=v9v}|@b{-xarch=v9m}|@b{-xarch=sparc}|@b{-xarch=sparcvis}
594 @b{-xarch=sparcvis2}|@b{-xarch=sparcfmaf}|@b{-xarch=sparcima}
595 @b{-xarch=sparcvis3}|@b{-xarch=sparcvisr}|@b{-xarch=sparc5}
598 [@b{--enforce-aligned-data}][@b{--dcti-couples-detect}]
602 @emph{Target TIC54X options:}
603 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
604 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
608 @emph{Target TIC6X options:}
609 [@b{-march=@var{arch}}] [@b{-mbig-endian}|@b{-mlittle-endian}]
610 [@b{-mdsbt}|@b{-mno-dsbt}] [@b{-mpid=no}|@b{-mpid=near}|@b{-mpid=far}]
611 [@b{-mpic}|@b{-mno-pic}]
615 @emph{Target TILE-Gx options:}
616 [@b{-m32}|@b{-m64}][@b{-EB}][@b{-EL}]
619 @c TILEPro has no machine-dependent assembler options
623 @emph{Target Visium options:}
624 [@b{-mtune=@var{arch}}]
628 @emph{Target Xtensa options:}
629 [@b{--[no-]text-section-literals}] [@b{--[no-]auto-litpools}]
630 [@b{--[no-]absolute-literals}]
631 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
632 [@b{--[no-]transform}]
633 [@b{--rename-section} @var{oldname}=@var{newname}]
634 [@b{--[no-]trampolines}]
635 [@b{--abi-windowed}|@b{--abi-call0}]
639 @emph{Target Z80 options:}
640 [@b{-march=@var{CPU}@var{[-EXT]}@var{[+EXT]}}]
641 [@b{-local-prefix=}@var{PREFIX}]
644 [@b{-fp-s=}@var{FORMAT}]
645 [@b{-fp-d=}@var{FORMAT}]
649 @c Z8000 has no machine-dependent assembler options
658 @include at-file.texi
661 Turn on listings, in any of a variety of ways:
665 omit false conditionals
668 omit debugging directives
671 include general information, like @value{AS} version and options passed
674 include high-level source
680 include macro expansions
683 omit forms processing
689 set the name of the listing file
692 You may combine these options; for example, use @samp{-aln} for assembly
693 listing without forms processing. The @samp{=file} option, if used, must be
694 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
697 Begin in alternate macro mode.
699 @xref{Altmacro,,@code{.altmacro}}.
702 @item --compress-debug-sections
703 Compress DWARF debug sections using zlib with SHF_COMPRESSED from the
704 ELF ABI. The resulting object file may not be compatible with older
705 linkers and object file utilities. Note if compression would make a
706 given section @emph{larger} then it is not compressed.
709 @cindex @samp{--compress-debug-sections=} option
710 @item --compress-debug-sections=none
711 @itemx --compress-debug-sections=zlib
712 @itemx --compress-debug-sections=zlib-gnu
713 @itemx --compress-debug-sections=zlib-gabi
714 These options control how DWARF debug sections are compressed.
715 @option{--compress-debug-sections=none} is equivalent to
716 @option{--nocompress-debug-sections}.
717 @option{--compress-debug-sections=zlib} and
718 @option{--compress-debug-sections=zlib-gabi} are equivalent to
719 @option{--compress-debug-sections}.
720 @option{--compress-debug-sections=zlib-gnu} compresses DWARF debug
721 sections using zlib. The debug sections are renamed to begin with
722 @samp{.zdebug}. Note if compression would make a given section
723 @emph{larger} then it is not compressed nor renamed.
727 @item --nocompress-debug-sections
728 Do not compress DWARF debug sections. This is usually the default for all
729 targets except the x86/x86_64, but a configure time option can be used to
733 Ignored. This option is accepted for script compatibility with calls to
736 @item --debug-prefix-map @var{old}=@var{new}
737 When assembling files in directory @file{@var{old}}, record debugging
738 information describing them as in @file{@var{new}} instead.
740 @item --defsym @var{sym}=@var{value}
741 Define the symbol @var{sym} to be @var{value} before assembling the input file.
742 @var{value} must be an integer constant. As in C, a leading @samp{0x}
743 indicates a hexadecimal value, and a leading @samp{0} indicates an octal
744 value. The value of the symbol can be overridden inside a source file via the
745 use of a @code{.set} pseudo-op.
748 ``fast''---skip whitespace and comment preprocessing (assume source is
753 Generate debugging information for each assembler source line using whichever
754 debug format is preferred by the target. This currently means either STABS,
755 ECOFF or DWARF2. When the debug format is DWARF then a @code{.debug_info} and
756 @code{.debug_line} section is only emitted when the assembly file doesn't
760 Generate stabs debugging information for each assembler line. This
761 may help debugging assembler code, if the debugger can handle it.
764 Generate stabs debugging information for each assembler line, with GNU
765 extensions that probably only gdb can handle, and that could make other
766 debuggers crash or refuse to read your program. This
767 may help debugging assembler code. Currently the only GNU extension is
768 the location of the current working directory at assembling time.
771 Generate DWARF2 debugging information for each assembler line. This
772 may help debugging assembler code, if the debugger can handle it. Note---this
773 option is only supported by some targets, not all of them.
776 This option is the same as the @option{--gdwarf-2} option, except that it
777 allows for the possibility of the generation of extra debug information as per
778 version 3 of the DWARF specification. Note - enabling this option does not
779 guarantee the generation of any extra information, the choice to do so is on a
783 This option is the same as the @option{--gdwarf-2} option, except that it
784 allows for the possibility of the generation of extra debug information as per
785 version 4 of the DWARF specification. Note - enabling this option does not
786 guarantee the generation of any extra information, the choice to do so is on a
790 This option is the same as the @option{--gdwarf-2} option, except that it
791 allows for the possibility of the generation of extra debug information as per
792 version 5 of the DWARF specification. Note - enabling this option does not
793 guarantee the generation of any extra information, the choice to do so is on a
796 @item --gdwarf-sections
797 Instead of creating a .debug_line section, create a series of
798 .debug_line.@var{foo} sections where @var{foo} is the name of the
799 corresponding code section. For example a code section called @var{.text.func}
800 will have its dwarf line number information placed into a section called
801 @var{.debug_line.text.func}. If the code section is just called @var{.text}
802 then debug line section will still be called just @var{.debug_line} without any
805 @item --gdwarf-cie-version=@var{version}
806 Control which version of DWARF Common Information Entries (CIEs) are produced.
807 When this flag is not specificed the default is version 1, though some targets
808 can modify this default. Other possible values for @var{version} are 3 or 4.
811 @item --size-check=error
812 @itemx --size-check=warning
813 Issue an error or warning for invalid ELF .size directive.
815 @item --elf-stt-common=no
816 @itemx --elf-stt-common=yes
817 These options control whether the ELF assembler should generate common
818 symbols with the @code{STT_COMMON} type. The default can be controlled
819 by a configure option @option{--enable-elf-stt-common}.
821 @item --generate-missing-build-notes=yes
822 @itemx --generate-missing-build-notes=no
823 These options control whether the ELF assembler should generate GNU Build
824 attribute notes if none are present in the input sources.
825 The default can be controlled by the @option{--enable-generate-build-notes}
831 Print a summary of the command-line options and exit.
834 Print a summary of all target specific options and exit.
837 Add directory @var{dir} to the search list for @code{.include} directives.
840 Don't warn about signed overflow.
843 @ifclear DIFF-TBL-KLUGE
844 This option is accepted but has no effect on the @value{TARGET} family.
846 @ifset DIFF-TBL-KLUGE
847 Issue warnings when difference tables altered for long displacements.
852 Keep (in the symbol table) local symbols. These symbols start with
853 system-specific local label prefixes, typically @samp{.L} for ELF systems
854 or @samp{L} for traditional a.out systems.
859 @item --listing-lhs-width=@var{number}
860 Set the maximum width, in words, of the output data column for an assembler
861 listing to @var{number}.
863 @item --listing-lhs-width2=@var{number}
864 Set the maximum width, in words, of the output data column for continuation
865 lines in an assembler listing to @var{number}.
867 @item --listing-rhs-width=@var{number}
868 Set the maximum width of an input source line, as displayed in a listing, to
871 @item --listing-cont-lines=@var{number}
872 Set the maximum number of lines printed in a listing for a single line of input
875 @item --multibyte-handling=allow
876 @itemx --multibyte-handling=warn
877 @itemx --multibyte-handling=warn-sym-only
878 Controls how the assembler handles multibyte characters in the input. The
879 default (which can be restored by using the @option{allow} argument) is to
880 allow such characters without complaint. Using the @option{warn} argument will
881 make the assembler generate a warning message whenever any multibyte character
882 is encountered. Using the @option{warn-sym-only} argument will only cause a
883 warning to be generated when a symbol is defined with a name that contains
884 multibyte characters. (References to undefined symbols will not generate a
887 @item --no-pad-sections
888 Stop the assembler for padding the ends of output sections to the alignment
889 of that section. The default is to pad the sections, but this can waste space
890 which might be needed on targets which have tight memory constraints.
892 @item -o @var{objfile}
893 Name the object-file output from @command{@value{AS}} @var{objfile}.
896 Fold the data section into the text section.
899 @item --sectname-subst
900 Honor substitution sequences in section names.
902 @xref{Section Name Substitutions,,@code{.section @var{name}}}.
907 Print the maximum space (in bytes) and total time (in seconds) used by
910 @item --strip-local-absolute
911 Remove local absolute symbols from the outgoing symbol table.
915 Print the @command{as} version.
918 Print the @command{as} version and exit.
922 Suppress warning messages.
924 @item --fatal-warnings
925 Treat warnings as errors.
928 Don't suppress warning messages or treat them as errors.
937 Generate an object file even after errors.
939 @item -- | @var{files} @dots{}
940 Standard input, or source files to assemble.
948 @xref{AArch64 Options}, for the options available when @value{AS} is configured
949 for the 64-bit mode of the ARM Architecture (AArch64).
954 The following options are available when @value{AS} is configured for the
955 64-bit mode of the ARM Architecture (AArch64).
958 @include c-aarch64.texi
959 @c ended inside the included file
967 @xref{Alpha Options}, for the options available when @value{AS} is configured
968 for an Alpha processor.
973 The following options are available when @value{AS} is configured for an Alpha
977 @include c-alpha.texi
978 @c ended inside the included file
985 The following options are available when @value{AS} is configured for an ARC
989 @item -mcpu=@var{cpu}
990 This option selects the core processor variant.
992 Select either big-endian (-EB) or little-endian (-EL) output.
994 Enable Code Density extension instructions.
999 The following options are available when @value{AS} is configured for the ARM
1003 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
1004 Specify which ARM processor variant is the target.
1005 @item -march=@var{architecture}[+@var{extension}@dots{}]
1006 Specify which ARM architecture variant is used by the target.
1007 @item -mfpu=@var{floating-point-format}
1008 Select which Floating Point architecture is the target.
1009 @item -mfloat-abi=@var{abi}
1010 Select which floating point ABI is in use.
1012 Enable Thumb only instruction decoding.
1013 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
1014 Select which procedure calling convention is in use.
1016 Select either big-endian (-EB) or little-endian (-EL) output.
1017 @item -mthumb-interwork
1018 Specify that the code has been generated with interworking between Thumb and
1021 Turns on CodeComposer Studio assembly syntax compatibility mode.
1023 Specify that PIC code has been generated.
1031 @xref{Blackfin Options}, for the options available when @value{AS} is
1032 configured for the Blackfin processor family.
1036 @c man begin OPTIONS
1037 The following options are available when @value{AS} is configured for
1038 the Blackfin processor family.
1040 @c man begin INCLUDE
1041 @include c-bfin.texi
1042 @c ended inside the included file
1050 @xref{BPF Options}, for the options available when @value{AS} is
1051 configured for the Linux kernel BPF processor family.
1055 @c man begin OPTIONS
1056 The following options are available when @value{AS} is configured for
1057 the Linux kernel BPF processor family.
1059 @c man begin INCLUDE
1061 @c ended inside the included file
1066 @c man begin OPTIONS
1068 See the info pages for documentation of the CRIS-specific options.
1074 @xref{C-SKY Options}, for the options available when @value{AS} is
1075 configured for the C-SKY processor family.
1079 @c man begin OPTIONS
1080 The following options are available when @value{AS} is configured for
1081 the C-SKY processor family.
1083 @c man begin INCLUDE
1084 @include c-csky.texi
1085 @c ended inside the included file
1091 The following options are available when @value{AS} is configured for
1094 @cindex D10V optimization
1095 @cindex optimization, D10V
1097 Optimize output by parallelizing instructions.
1102 The following options are available when @value{AS} is configured for a D30V
1105 @cindex D30V optimization
1106 @cindex optimization, D30V
1108 Optimize output by parallelizing instructions.
1112 Warn when nops are generated.
1114 @cindex D30V nops after 32-bit multiply
1116 Warn when a nop after a 32-bit multiply instruction is generated.
1122 The following options are available when @value{AS} is configured for the
1123 Adapteva EPIPHANY series.
1126 @xref{Epiphany Options}, for the options available when @value{AS} is
1127 configured for an Epiphany processor.
1131 @c man begin OPTIONS
1132 The following options are available when @value{AS} is configured for
1133 an Epiphany processor.
1135 @c man begin INCLUDE
1136 @include c-epiphany.texi
1137 @c ended inside the included file
1145 @xref{H8/300 Options}, for the options available when @value{AS} is configured
1146 for an H8/300 processor.
1150 @c man begin OPTIONS
1151 The following options are available when @value{AS} is configured for an H8/300
1154 @c man begin INCLUDE
1155 @include c-h8300.texi
1156 @c ended inside the included file
1164 @xref{i386-Options}, for the options available when @value{AS} is
1165 configured for an i386 processor.
1169 @c man begin OPTIONS
1170 The following options are available when @value{AS} is configured for
1173 @c man begin INCLUDE
1174 @include c-i386.texi
1175 @c ended inside the included file
1180 @c man begin OPTIONS
1182 The following options are available when @value{AS} is configured for the
1188 Specifies that the extended IP2022 instructions are allowed.
1191 Restores the default behaviour, which restricts the permitted instructions to
1192 just the basic IP2022 ones.
1198 The following options are available when @value{AS} is configured for the
1199 Renesas M32C and M16C processors.
1204 Assemble M32C instructions.
1207 Assemble M16C instructions (the default).
1210 Enable support for link-time relaxations.
1213 Support H'00 style hex constants in addition to 0x00 style.
1219 The following options are available when @value{AS} is configured for the
1220 Renesas M32R (formerly Mitsubishi M32R) series.
1225 Specify which processor in the M32R family is the target. The default
1226 is normally the M32R, but this option changes it to the M32RX.
1228 @item --warn-explicit-parallel-conflicts or --Wp
1229 Produce warning messages when questionable parallel constructs are
1232 @item --no-warn-explicit-parallel-conflicts or --Wnp
1233 Do not produce warning messages when questionable parallel constructs are
1240 The following options are available when @value{AS} is configured for the
1241 Motorola 68000 series.
1246 Shorten references to undefined symbols, to one word instead of two.
1248 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
1249 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
1250 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
1251 Specify what processor in the 68000 family is the target. The default
1252 is normally the 68020, but this can be changed at configuration time.
1254 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
1255 The target machine does (or does not) have a floating-point coprocessor.
1256 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
1257 the basic 68000 is not compatible with the 68881, a combination of the
1258 two can be specified, since it's possible to do emulation of the
1259 coprocessor instructions with the main processor.
1261 @item -m68851 | -mno-68851
1262 The target machine does (or does not) have a memory-management
1263 unit coprocessor. The default is to assume an MMU for 68020 and up.
1271 @xref{Nios II Options}, for the options available when @value{AS} is configured
1272 for an Altera Nios II processor.
1276 @c man begin OPTIONS
1277 The following options are available when @value{AS} is configured for an
1278 Altera Nios II processor.
1280 @c man begin INCLUDE
1281 @include c-nios2.texi
1282 @c ended inside the included file
1288 For details about the PDP-11 machine dependent features options,
1289 see @ref{PDP-11-Options}.
1292 @item -mpic | -mno-pic
1293 Generate position-independent (or position-dependent) code. The
1294 default is @option{-mpic}.
1297 @itemx -mall-extensions
1298 Enable all instruction set extensions. This is the default.
1300 @item -mno-extensions
1301 Disable all instruction set extensions.
1303 @item -m@var{extension} | -mno-@var{extension}
1304 Enable (or disable) a particular instruction set extension.
1307 Enable the instruction set extensions supported by a particular CPU, and
1308 disable all other extensions.
1310 @item -m@var{machine}
1311 Enable the instruction set extensions supported by a particular machine
1312 model, and disable all other extensions.
1318 The following options are available when @value{AS} is configured for
1319 a picoJava processor.
1323 @cindex PJ endianness
1324 @cindex endianness, PJ
1325 @cindex big endian output, PJ
1327 Generate ``big endian'' format output.
1329 @cindex little endian output, PJ
1331 Generate ``little endian'' format output.
1339 @xref{PRU Options}, for the options available when @value{AS} is configured
1340 for a PRU processor.
1344 @c man begin OPTIONS
1345 The following options are available when @value{AS} is configured for a
1348 @c man begin INCLUDE
1350 @c ended inside the included file
1355 The following options are available when @value{AS} is configured for the
1356 Motorola 68HC11 or 68HC12 series.
1360 @item -m68hc11 | -m68hc12 | -m68hcs12 | -mm9s12x | -mm9s12xg
1361 Specify what processor is the target. The default is
1362 defined by the configuration option when building the assembler.
1364 @item --xgate-ramoffset
1365 Instruct the linker to offset RAM addresses from S12X address space into
1366 XGATE address space.
1369 Specify to use the 16-bit integer ABI.
1372 Specify to use the 32-bit integer ABI.
1374 @item -mshort-double
1375 Specify to use the 32-bit double ABI.
1378 Specify to use the 64-bit double ABI.
1380 @item --force-long-branches
1381 Relative branches are turned into absolute ones. This concerns
1382 conditional branches, unconditional branches and branches to a
1385 @item -S | --short-branches
1386 Do not turn relative branches into absolute ones
1387 when the offset is out of range.
1389 @item --strict-direct-mode
1390 Do not turn the direct addressing mode into extended addressing mode
1391 when the instruction does not support direct addressing mode.
1393 @item --print-insn-syntax
1394 Print the syntax of instruction in case of error.
1396 @item --print-opcodes
1397 Print the list of instructions with syntax and then exit.
1399 @item --generate-example
1400 Print an example of instruction for each possible instruction and then exit.
1401 This option is only useful for testing @command{@value{AS}}.
1407 The following options are available when @command{@value{AS}} is configured
1408 for the SPARC architecture:
1411 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
1412 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
1413 Explicitly select a variant of the SPARC architecture.
1415 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
1416 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
1418 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
1419 UltraSPARC extensions.
1421 @item -xarch=v8plus | -xarch=v8plusa
1422 For compatibility with the Solaris v9 assembler. These options are
1423 equivalent to -Av8plus and -Av8plusa, respectively.
1426 Warn when the assembler switches to another architecture.
1431 The following options are available when @value{AS} is configured for the 'c54x
1436 Enable extended addressing mode. All addresses and relocations will assume
1437 extended addressing (usually 23 bits).
1438 @item -mcpu=@var{CPU_VERSION}
1439 Sets the CPU version being compiled for.
1440 @item -merrors-to-file @var{FILENAME}
1441 Redirect error output to a file, for broken systems which don't support such
1442 behaviour in the shell.
1447 @c man begin OPTIONS
1448 The following options are available when @value{AS} is configured for
1453 This option sets the largest size of an object that can be referenced
1454 implicitly with the @code{gp} register. It is only accepted for targets that
1455 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
1457 @cindex MIPS endianness
1458 @cindex endianness, MIPS
1459 @cindex big endian output, MIPS
1461 Generate ``big endian'' format output.
1463 @cindex little endian output, MIPS
1465 Generate ``little endian'' format output.
1483 Generate code for a particular MIPS Instruction Set Architecture level.
1484 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
1485 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
1486 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
1487 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips32r3},
1488 @samp{-mips32r5}, @samp{-mips32r6}, @samp{-mips64}, @samp{-mips64r2},
1489 @samp{-mips64r3}, @samp{-mips64r5}, and @samp{-mips64r6} correspond to generic
1490 MIPS V, MIPS32, MIPS32 Release 2, MIPS32 Release 3, MIPS32 Release 5, MIPS32
1491 Release 6, MIPS64, MIPS64 Release 2, MIPS64 Release 3, MIPS64 Release 5, and
1492 MIPS64 Release 6 ISA processors, respectively.
1494 @item -march=@var{cpu}
1495 Generate code for a particular MIPS CPU.
1497 @item -mtune=@var{cpu}
1498 Schedule and tune for a particular MIPS CPU.
1502 Cause nops to be inserted if the read of the destination register
1503 of an mfhi or mflo instruction occurs in the following two instructions.
1506 @itemx -mno-fix-rm7000
1507 Cause nops to be inserted if a dmult or dmultu instruction is
1508 followed by a load instruction.
1511 @itemx -mno-fix-r5900
1512 Do not attempt to schedule the preceding instruction into the delay slot
1513 of a branch instruction placed at the end of a short loop of six
1514 instructions or fewer and always schedule a @code{nop} instruction there
1515 instead. The short loop bug under certain conditions causes loops to
1516 execute only once or twice, due to a hardware bug in the R5900 chip.
1520 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
1521 section instead of the standard ELF .stabs sections.
1525 Control generation of @code{.pdr} sections.
1529 The register sizes are normally inferred from the ISA and ABI, but these
1530 flags force a certain group of registers to be treated as 32 bits wide at
1531 all times. @samp{-mgp32} controls the size of general-purpose registers
1532 and @samp{-mfp32} controls the size of floating-point registers.
1536 The register sizes are normally inferred from the ISA and ABI, but these
1537 flags force a certain group of registers to be treated as 64 bits wide at
1538 all times. @samp{-mgp64} controls the size of general-purpose registers
1539 and @samp{-mfp64} controls the size of floating-point registers.
1542 The register sizes are normally inferred from the ISA and ABI, but using
1543 this flag in combination with @samp{-mabi=32} enables an ABI variant
1544 which will operate correctly with floating-point registers which are
1548 @itemx -mno-odd-spreg
1549 Enable use of floating-point operations on odd-numbered single-precision
1550 registers when supported by the ISA. @samp{-mfpxx} implies
1551 @samp{-mno-odd-spreg}, otherwise the default is @samp{-modd-spreg}.
1555 Generate code for the MIPS 16 processor. This is equivalent to putting
1556 @code{.module mips16} at the start of the assembly file. @samp{-no-mips16}
1557 turns off this option.
1560 @itemx -mno-mips16e2
1561 Enable the use of MIPS16e2 instructions in MIPS16 mode. This is equivalent
1562 to putting @code{.module mips16e2} at the start of the assembly file.
1563 @samp{-mno-mips16e2} turns off this option.
1566 @itemx -mno-micromips
1567 Generate code for the microMIPS processor. This is equivalent to putting
1568 @code{.module micromips} at the start of the assembly file.
1569 @samp{-mno-micromips} turns off this option. This is equivalent to putting
1570 @code{.module nomicromips} at the start of the assembly file.
1573 @itemx -mno-smartmips
1574 Enables the SmartMIPS extension to the MIPS32 instruction set. This is
1575 equivalent to putting @code{.module smartmips} at the start of the assembly
1576 file. @samp{-mno-smartmips} turns off this option.
1580 Generate code for the MIPS-3D Application Specific Extension.
1581 This tells the assembler to accept MIPS-3D instructions.
1582 @samp{-no-mips3d} turns off this option.
1586 Generate code for the MDMX Application Specific Extension.
1587 This tells the assembler to accept MDMX instructions.
1588 @samp{-no-mdmx} turns off this option.
1592 Generate code for the DSP Release 1 Application Specific Extension.
1593 This tells the assembler to accept DSP Release 1 instructions.
1594 @samp{-mno-dsp} turns off this option.
1598 Generate code for the DSP Release 2 Application Specific Extension.
1599 This option implies @samp{-mdsp}.
1600 This tells the assembler to accept DSP Release 2 instructions.
1601 @samp{-mno-dspr2} turns off this option.
1605 Generate code for the DSP Release 3 Application Specific Extension.
1606 This option implies @samp{-mdsp} and @samp{-mdspr2}.
1607 This tells the assembler to accept DSP Release 3 instructions.
1608 @samp{-mno-dspr3} turns off this option.
1612 Generate code for the MIPS SIMD Architecture Extension.
1613 This tells the assembler to accept MSA instructions.
1614 @samp{-mno-msa} turns off this option.
1618 Generate code for the MIPS eXtended Physical Address (XPA) Extension.
1619 This tells the assembler to accept XPA instructions.
1620 @samp{-mno-xpa} turns off this option.
1624 Generate code for the MT Application Specific Extension.
1625 This tells the assembler to accept MT instructions.
1626 @samp{-mno-mt} turns off this option.
1630 Generate code for the MCU Application Specific Extension.
1631 This tells the assembler to accept MCU instructions.
1632 @samp{-mno-mcu} turns off this option.
1636 Generate code for the MIPS cyclic redundancy check (CRC) Application
1637 Specific Extension. This tells the assembler to accept CRC instructions.
1638 @samp{-mno-crc} turns off this option.
1642 Generate code for the Global INValidate (GINV) Application Specific
1643 Extension. This tells the assembler to accept GINV instructions.
1644 @samp{-mno-ginv} turns off this option.
1646 @item -mloongson-mmi
1647 @itemx -mno-loongson-mmi
1648 Generate code for the Loongson MultiMedia extensions Instructions (MMI)
1649 Application Specific Extension. This tells the assembler to accept MMI
1651 @samp{-mno-loongson-mmi} turns off this option.
1653 @item -mloongson-cam
1654 @itemx -mno-loongson-cam
1655 Generate code for the Loongson Content Address Memory (CAM) instructions.
1656 This tells the assembler to accept Loongson CAM instructions.
1657 @samp{-mno-loongson-cam} turns off this option.
1659 @item -mloongson-ext
1660 @itemx -mno-loongson-ext
1661 Generate code for the Loongson EXTensions (EXT) instructions.
1662 This tells the assembler to accept Loongson EXT instructions.
1663 @samp{-mno-loongson-ext} turns off this option.
1665 @item -mloongson-ext2
1666 @itemx -mno-loongson-ext2
1667 Generate code for the Loongson EXTensions R2 (EXT2) instructions.
1668 This option implies @samp{-mloongson-ext}.
1669 This tells the assembler to accept Loongson EXT2 instructions.
1670 @samp{-mno-loongson-ext2} turns off this option.
1674 Only use 32-bit instruction encodings when generating code for the
1675 microMIPS processor. This option inhibits the use of any 16-bit
1676 instructions. This is equivalent to putting @code{.set insn32} at
1677 the start of the assembly file. @samp{-mno-insn32} turns off this
1678 option. This is equivalent to putting @code{.set noinsn32} at the
1679 start of the assembly file. By default @samp{-mno-insn32} is
1680 selected, allowing all instructions to be used.
1682 @item --construct-floats
1683 @itemx --no-construct-floats
1684 The @samp{--no-construct-floats} option disables the construction of
1685 double width floating point constants by loading the two halves of the
1686 value into the two single width floating point registers that make up
1687 the double width register. By default @samp{--construct-floats} is
1688 selected, allowing construction of these floating point constants.
1690 @item --relax-branch
1691 @itemx --no-relax-branch
1692 The @samp{--relax-branch} option enables the relaxation of out-of-range
1693 branches. By default @samp{--no-relax-branch} is selected, causing any
1694 out-of-range branches to produce an error.
1696 @item -mignore-branch-isa
1697 @itemx -mno-ignore-branch-isa
1698 Ignore branch checks for invalid transitions between ISA modes. The
1699 semantics of branches does not provide for an ISA mode switch, so in
1700 most cases the ISA mode a branch has been encoded for has to be the
1701 same as the ISA mode of the branch's target label. Therefore GAS has
1702 checks implemented that verify in branch assembly that the two ISA
1703 modes match. @samp{-mignore-branch-isa} disables these checks. By
1704 default @samp{-mno-ignore-branch-isa} is selected, causing any invalid
1705 branch requiring a transition between ISA modes to produce an error.
1707 @item -mnan=@var{encoding}
1708 Select between the IEEE 754-2008 (@option{-mnan=2008}) or the legacy
1709 (@option{-mnan=legacy}) NaN encoding format. The latter is the default.
1712 @item --emulation=@var{name}
1713 This option was formerly used to switch between ELF and ECOFF output
1714 on targets like IRIX 5 that supported both. MIPS ECOFF support was
1715 removed in GAS 2.24, so the option now serves little purpose.
1716 It is retained for backwards compatibility.
1718 The available configuration names are: @samp{mipself}, @samp{mipslelf} and
1719 @samp{mipsbelf}. Choosing @samp{mipself} now has no effect, since the output
1720 is always ELF. @samp{mipslelf} and @samp{mipsbelf} select little- and
1721 big-endian output respectively, but @samp{-EL} and @samp{-EB} are now the
1722 preferred options instead.
1725 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1732 Control how to deal with multiplication overflow and division by zero.
1733 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1734 (and only work for Instruction Set Architecture level 2 and higher);
1735 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1739 When this option is used, @command{@value{AS}} will issue a warning every
1740 time it generates a nop instruction from a macro.
1746 The following options are available when @value{AS} is configured for
1752 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1753 The command-line option @samp{-nojsri2bsr} can be used to disable it.
1757 Enable or disable the silicon filter behaviour. By default this is disabled.
1758 The default can be overridden by the @samp{-sifilter} command-line option.
1761 Alter jump instructions for long displacements.
1763 @item -mcpu=[210|340]
1764 Select the cpu type on the target hardware. This controls which instructions
1768 Assemble for a big endian target.
1771 Assemble for a little endian target.
1780 @xref{LoongArch-Options}, for the options available when @value{AS} is configured
1781 for a LoongArch processor.
1785 @c man begin OPTIONS
1786 The following options are available when @value{AS} is configured for a
1787 LoongArch processor.
1789 @c man begin INCLUDE
1790 @include c-loongarch.texi
1791 @c ended inside the included file
1799 @xref{Meta Options}, for the options available when @value{AS} is configured
1800 for a Meta processor.
1804 @c man begin OPTIONS
1805 The following options are available when @value{AS} is configured for a
1808 @c man begin INCLUDE
1809 @include c-metag.texi
1810 @c ended inside the included file
1815 @c man begin OPTIONS
1817 See the info pages for documentation of the MMIX-specific options.
1823 @xref{NDS32 Options}, for the options available when @value{AS} is configured
1824 for a NDS32 processor.
1826 @c ended inside the included file
1830 @c man begin OPTIONS
1831 The following options are available when @value{AS} is configured for a
1834 @c man begin INCLUDE
1835 @include c-nds32.texi
1836 @c ended inside the included file
1843 @xref{PowerPC-Opts}, for the options available when @value{AS} is configured
1844 for a PowerPC processor.
1848 @c man begin OPTIONS
1849 The following options are available when @value{AS} is configured for a
1852 @c man begin INCLUDE
1854 @c ended inside the included file
1862 @xref{RISC-V-Options}, for the options available when @value{AS} is configured
1863 for a RISC-V processor.
1867 @c man begin OPTIONS
1868 The following options are available when @value{AS} is configured for a
1871 @c man begin INCLUDE
1872 @include c-riscv.texi
1873 @c ended inside the included file
1878 @c man begin OPTIONS
1880 See the info pages for documentation of the RX-specific options.
1884 The following options are available when @value{AS} is configured for the s390
1890 Select the word size, either 31/32 bits or 64 bits.
1893 Select the architecture mode, either the Enterprise System
1894 Architecture (esa) or the z/Architecture mode (zarch).
1895 @item -march=@var{processor}
1896 Specify which s390 processor variant is the target, @samp{g5} (or
1897 @samp{arch3}), @samp{g6}, @samp{z900} (or @samp{arch5}), @samp{z990} (or
1898 @samp{arch6}), @samp{z9-109}, @samp{z9-ec} (or @samp{arch7}), @samp{z10} (or
1899 @samp{arch8}), @samp{z196} (or @samp{arch9}), @samp{zEC12} (or @samp{arch10}),
1900 @samp{z13} (or @samp{arch11}), @samp{z14} (or @samp{arch12}), or @samp{z15}
1903 @itemx -mno-regnames
1904 Allow or disallow symbolic names for registers.
1905 @item -mwarn-areg-zero
1906 Warn whenever the operand for a base or index register has been specified
1907 but evaluates to zero.
1915 @xref{TIC6X Options}, for the options available when @value{AS} is configured
1916 for a TMS320C6000 processor.
1920 @c man begin OPTIONS
1921 The following options are available when @value{AS} is configured for a
1922 TMS320C6000 processor.
1924 @c man begin INCLUDE
1925 @include c-tic6x.texi
1926 @c ended inside the included file
1934 @xref{TILE-Gx Options}, for the options available when @value{AS} is configured
1935 for a TILE-Gx processor.
1939 @c man begin OPTIONS
1940 The following options are available when @value{AS} is configured for a TILE-Gx
1943 @c man begin INCLUDE
1944 @include c-tilegx.texi
1945 @c ended inside the included file
1953 @xref{Visium Options}, for the options available when @value{AS} is configured
1954 for a Visium processor.
1958 @c man begin OPTIONS
1959 The following option is available when @value{AS} is configured for a Visium
1962 @c man begin INCLUDE
1963 @include c-visium.texi
1964 @c ended inside the included file
1972 @xref{Xtensa Options}, for the options available when @value{AS} is configured
1973 for an Xtensa processor.
1977 @c man begin OPTIONS
1978 The following options are available when @value{AS} is configured for an
1981 @c man begin INCLUDE
1982 @include c-xtensa.texi
1983 @c ended inside the included file
1991 @xref{Z80 Options}, for the options available when @value{AS} is configured
1992 for an Z80 processor.
1996 @c man begin OPTIONS
1997 The following options are available when @value{AS} is configured for an
2000 @c man begin INCLUDE
2002 @c ended inside the included file
2008 * Manual:: Structure of this Manual
2009 * GNU Assembler:: The GNU Assembler
2010 * Object Formats:: Object File Formats
2011 * Command Line:: Command Line
2012 * Input Files:: Input Files
2013 * Object:: Output (Object) File
2014 * Errors:: Error and Warning Messages
2018 @section Structure of this Manual
2020 @cindex manual, structure and purpose
2021 This manual is intended to describe what you need to know to use
2022 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
2023 notation for symbols, constants, and expressions; the directives that
2024 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
2027 We also cover special features in the @value{TARGET}
2028 configuration of @command{@value{AS}}, including assembler directives.
2031 This manual also describes some of the machine-dependent features of
2032 various flavors of the assembler.
2035 @cindex machine instructions (not covered)
2036 On the other hand, this manual is @emph{not} intended as an introduction
2037 to programming in assembly language---let alone programming in general!
2038 In a similar vein, we make no attempt to introduce the machine
2039 architecture; we do @emph{not} describe the instruction set, standard
2040 mnemonics, registers or addressing modes that are standard to a
2041 particular architecture.
2043 You may want to consult the manufacturer's
2044 machine architecture manual for this information.
2048 For information on the H8/300 machine instruction set, see @cite{H8/300
2049 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
2050 Programming Manual} (Renesas).
2053 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
2054 see @cite{SH-Microcomputer User's Manual} (Renesas) or
2055 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
2056 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
2059 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
2063 @c I think this is premature---doc@cygnus.com, 17jan1991
2065 Throughout this manual, we assume that you are running @dfn{GNU},
2066 the portable operating system from the @dfn{Free Software
2067 Foundation, Inc.}. This restricts our attention to certain kinds of
2068 computer (in particular, the kinds of computers that @sc{gnu} can run on);
2069 once this assumption is granted examples and definitions need less
2072 @command{@value{AS}} is part of a team of programs that turn a high-level
2073 human-readable series of instructions into a low-level
2074 computer-readable series of instructions. Different versions of
2075 @command{@value{AS}} are used for different kinds of computer.
2078 @c There used to be a section "Terminology" here, which defined
2079 @c "contents", "byte", "word", and "long". Defining "word" to any
2080 @c particular size is confusing when the .word directive may generate 16
2081 @c bits on one machine and 32 bits on another; in general, for the user
2082 @c version of this manual, none of these terms seem essential to define.
2083 @c They were used very little even in the former draft of the manual;
2084 @c this draft makes an effort to avoid them (except in names of
2088 @section The GNU Assembler
2090 @c man begin DESCRIPTION
2092 @sc{gnu} @command{as} is really a family of assemblers.
2094 This manual describes @command{@value{AS}}, a member of that family which is
2095 configured for the @value{TARGET} architectures.
2097 If you use (or have used) the @sc{gnu} assembler on one architecture, you
2098 should find a fairly similar environment when you use it on another
2099 architecture. Each version has much in common with the others,
2100 including object file formats, most assembler directives (often called
2101 @dfn{pseudo-ops}) and assembler syntax.@refill
2103 @cindex purpose of @sc{gnu} assembler
2104 @command{@value{AS}} is primarily intended to assemble the output of the
2105 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
2106 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
2107 assemble correctly everything that other assemblers for the same
2108 machine would assemble.
2110 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
2113 @c This remark should appear in generic version of manual; assumption
2114 @c here is that generic version sets M680x0.
2115 This doesn't mean @command{@value{AS}} always uses the same syntax as another
2116 assembler for the same architecture; for example, we know of several
2117 incompatible versions of 680x0 assembly language syntax.
2122 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
2123 program in one pass of the source file. This has a subtle impact on the
2124 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
2126 @node Object Formats
2127 @section Object File Formats
2129 @cindex object file format
2130 The @sc{gnu} assembler can be configured to produce several alternative
2131 object file formats. For the most part, this does not affect how you
2132 write assembly language programs; but directives for debugging symbols
2133 are typically different in different file formats. @xref{Symbol
2134 Attributes,,Symbol Attributes}.
2137 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
2138 @value{OBJ-NAME} format object files.
2140 @c The following should exhaust all configs that set MULTI-OBJ, ideally
2142 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
2143 SOM or ELF format object files.
2148 @section Command Line
2150 @cindex command line conventions
2152 After the program name @command{@value{AS}}, the command line may contain
2153 options and file names. Options may appear in any order, and may be
2154 before, after, or between file names. The order of file names is
2157 @cindex standard input, as input file
2159 @file{--} (two hyphens) by itself names the standard input file
2160 explicitly, as one of the files for @command{@value{AS}} to assemble.
2162 @cindex options, command line
2163 Except for @samp{--} any command-line argument that begins with a
2164 hyphen (@samp{-}) is an option. Each option changes the behavior of
2165 @command{@value{AS}}. No option changes the way another option works. An
2166 option is a @samp{-} followed by one or more letters; the case of
2167 the letter is important. All options are optional.
2169 Some options expect exactly one file name to follow them. The file
2170 name may either immediately follow the option's letter (compatible
2171 with older assemblers) or it may be the next command argument (@sc{gnu}
2172 standard). These two command lines are equivalent:
2175 @value{AS} -o my-object-file.o mumble.s
2176 @value{AS} -omy-object-file.o mumble.s
2180 @section Input Files
2183 @cindex source program
2184 @cindex files, input
2185 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
2186 describe the program input to one run of @command{@value{AS}}. The program may
2187 be in one or more files; how the source is partitioned into files
2188 doesn't change the meaning of the source.
2190 @c I added "con" prefix to "catenation" just to prove I can overcome my
2191 @c APL training... doc@cygnus.com
2192 The source program is a concatenation of the text in all the files, in the
2195 @c man begin DESCRIPTION
2196 Each time you run @command{@value{AS}} it assembles exactly one source
2197 program. The source program is made up of one or more files.
2198 (The standard input is also a file.)
2200 You give @command{@value{AS}} a command line that has zero or more input file
2201 names. The input files are read (from left file name to right). A
2202 command-line argument (in any position) that has no special meaning
2203 is taken to be an input file name.
2205 If you give @command{@value{AS}} no file names it attempts to read one input file
2206 from the @command{@value{AS}} standard input, which is normally your terminal. You
2207 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
2210 Use @samp{--} if you need to explicitly name the standard input file
2211 in your command line.
2213 If the source is empty, @command{@value{AS}} produces a small, empty object
2218 @subheading Filenames and Line-numbers
2220 @cindex input file linenumbers
2221 @cindex line numbers, in input files
2222 There are two ways of locating a line in the input file (or files) and
2223 either may be used in reporting error messages. One way refers to a line
2224 number in a physical file; the other refers to a line number in a
2225 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
2227 @dfn{Physical files} are those files named in the command line given
2228 to @command{@value{AS}}.
2230 @dfn{Logical files} are simply names declared explicitly by assembler
2231 directives; they bear no relation to physical files. Logical file names help
2232 error messages reflect the original source file, when @command{@value{AS}} source
2233 is itself synthesized from other files. @command{@value{AS}} understands the
2234 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
2235 @ref{File,,@code{.file}}.
2238 @section Output (Object) File
2244 Every time you run @command{@value{AS}} it produces an output file, which is
2245 your assembly language program translated into numbers. This file
2246 is the object file. Its default name is @code{a.out}.
2247 You can give it another name by using the @option{-o} option. Conventionally,
2248 object file names end with @file{.o}. The default name is used for historical
2249 reasons: older assemblers were capable of assembling self-contained programs
2250 directly into a runnable program. (For some formats, this isn't currently
2251 possible, but it can be done for the @code{a.out} format.)
2255 The object file is meant for input to the linker @code{@value{LD}}. It contains
2256 assembled program code, information to help @code{@value{LD}} integrate
2257 the assembled program into a runnable file, and (optionally) symbolic
2258 information for the debugger.
2260 @c link above to some info file(s) like the description of a.out.
2261 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
2264 @section Error and Warning Messages
2266 @c man begin DESCRIPTION
2268 @cindex error messages
2269 @cindex warning messages
2270 @cindex messages from assembler
2271 @command{@value{AS}} may write warnings and error messages to the standard error
2272 file (usually your terminal). This should not happen when a compiler
2273 runs @command{@value{AS}} automatically. Warnings report an assumption made so
2274 that @command{@value{AS}} could keep assembling a flawed program; errors report a
2275 grave problem that stops the assembly.
2279 @cindex format of warning messages
2280 Warning messages have the format
2283 file_name:@b{NNN}:Warning Message Text
2287 @cindex file names and line numbers, in warnings/errors
2288 (where @b{NNN} is a line number). If both a logical file name
2289 (@pxref{File,,@code{.file}}) and a logical line number
2291 (@pxref{Line,,@code{.line}})
2293 have been given then they will be used, otherwise the file name and line number
2294 in the current assembler source file will be used. The message text is
2295 intended to be self explanatory (in the grand Unix tradition).
2297 Note the file name must be set via the logical version of the @code{.file}
2298 directive, not the DWARF2 version of the @code{.file} directive. For example:
2302 error_assembler_source
2308 produces this output:
2312 asm.s:2: Error: no such instruction: `error_assembler_source'
2313 foo.c:31: Error: no such instruction: `error_c_source'
2316 @cindex format of error messages
2317 Error messages have the format
2320 file_name:@b{NNN}:FATAL:Error Message Text
2323 The file name and line number are derived as for warning
2324 messages. The actual message text may be rather less explanatory
2325 because many of them aren't supposed to happen.
2328 @chapter Command-Line Options
2330 @cindex options, all versions of assembler
2331 This chapter describes command-line options available in @emph{all}
2332 versions of the @sc{gnu} assembler; see @ref{Machine Dependencies},
2333 for options specific
2335 to the @value{TARGET} target.
2338 to particular machine architectures.
2341 @c man begin DESCRIPTION
2343 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
2344 you can use the @samp{-Wa} option to pass arguments through to the assembler.
2345 The assembler arguments must be separated from each other (and the @samp{-Wa})
2346 by commas. For example:
2349 gcc -c -g -O -Wa,-alh,-L file.c
2353 This passes two options to the assembler: @samp{-alh} (emit a listing to
2354 standard output with high-level and assembly source) and @samp{-L} (retain
2355 local symbols in the symbol table).
2357 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
2358 command-line options are automatically passed to the assembler by the compiler.
2359 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
2360 precisely what options it passes to each compilation pass, including the
2366 * a:: -a[cdghlns] enable listings
2367 * alternate:: --alternate enable alternate macro syntax
2368 * D:: -D for compatibility
2369 * f:: -f to work faster
2370 * I:: -I for .include search path
2371 @ifclear DIFF-TBL-KLUGE
2372 * K:: -K for compatibility
2374 @ifset DIFF-TBL-KLUGE
2375 * K:: -K for difference tables
2378 * L:: -L to retain local symbols
2379 * listing:: --listing-XXX to configure listing output
2380 * M:: -M or --mri to assemble in MRI compatibility mode
2381 * MD:: --MD for dependency tracking
2382 * no-pad-sections:: --no-pad-sections to stop section padding
2383 * o:: -o to name the object file
2384 * R:: -R to join data and text sections
2385 * statistics:: --statistics to see statistics about assembly
2386 * traditional-format:: --traditional-format for compatible output
2387 * v:: -v to announce version
2388 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
2389 * Z:: -Z to make object file even after errors
2393 @section Enable Listings: @option{-a[cdghlns]}
2403 @cindex listings, enabling
2404 @cindex assembly listings, enabling
2406 These options enable listing output from the assembler. By itself,
2407 @samp{-a} requests high-level, assembly, and symbols listing.
2408 You can use other letters to select specific options for the list:
2409 @samp{-ah} requests a high-level language listing,
2410 @samp{-al} requests an output-program assembly listing, and
2411 @samp{-as} requests a symbol table listing.
2412 High-level listings require that a compiler debugging option like
2413 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
2416 Use the @samp{-ag} option to print a first section with general assembly
2417 information, like @value{AS} version, switches passed, or time stamp.
2419 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
2420 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
2421 other conditional), or a true @code{.if} followed by an @code{.else}, will be
2422 omitted from the listing.
2424 Use the @samp{-ad} option to omit debugging directives from the
2427 Once you have specified one of these options, you can further control
2428 listing output and its appearance using the directives @code{.list},
2429 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
2431 The @samp{-an} option turns off all forms processing.
2432 If you do not request listing output with one of the @samp{-a} options, the
2433 listing-control directives have no effect.
2435 The letters after @samp{-a} may be combined into one option,
2436 @emph{e.g.}, @samp{-aln}.
2438 Note if the assembler source is coming from the standard input (e.g.,
2440 is being created by @code{@value{GCC}} and the @samp{-pipe} command-line switch
2441 is being used) then the listing will not contain any comments or preprocessor
2442 directives. This is because the listing code buffers input source lines from
2443 stdin only after they have been preprocessed by the assembler. This reduces
2444 memory usage and makes the code more efficient.
2447 @section @option{--alternate}
2450 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
2453 @section @option{-D}
2456 This option has no effect whatsoever, but it is accepted to make it more
2457 likely that scripts written for other assemblers also work with
2458 @command{@value{AS}}.
2461 @section Work Faster: @option{-f}
2464 @cindex trusted compiler
2465 @cindex faster processing (@option{-f})
2466 @samp{-f} should only be used when assembling programs written by a
2467 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
2468 and comment preprocessing on
2469 the input file(s) before assembling them. @xref{Preprocessing,
2473 @emph{Warning:} if you use @samp{-f} when the files actually need to be
2474 preprocessed (if they contain comments, for example), @command{@value{AS}} does
2479 @section @code{.include} Search Path: @option{-I} @var{path}
2481 @kindex -I @var{path}
2482 @cindex paths for @code{.include}
2483 @cindex search path for @code{.include}
2484 @cindex @code{include} directive search path
2485 Use this option to add a @var{path} to the list of directories
2486 @command{@value{AS}} searches for files specified in @code{.include}
2487 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
2488 many times as necessary to include a variety of paths. The current
2489 working directory is always searched first; after that, @command{@value{AS}}
2490 searches any @samp{-I} directories in the same order as they were
2491 specified (left to right) on the command line.
2494 @section Difference Tables: @option{-K}
2497 @ifclear DIFF-TBL-KLUGE
2498 On the @value{TARGET} family, this option is allowed, but has no effect. It is
2499 permitted for compatibility with the @sc{gnu} assembler on other platforms,
2500 where it can be used to warn when the assembler alters the machine code
2501 generated for @samp{.word} directives in difference tables. The @value{TARGET}
2502 family does not have the addressing limitations that sometimes lead to this
2503 alteration on other platforms.
2506 @ifset DIFF-TBL-KLUGE
2507 @cindex difference tables, warning
2508 @cindex warning for altered difference tables
2509 @command{@value{AS}} sometimes alters the code emitted for directives of the
2510 form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}.
2511 You can use the @samp{-K} option if you want a warning issued when this
2516 @section Include Local Symbols: @option{-L}
2519 @cindex local symbols, retaining in output
2520 Symbols beginning with system-specific local label prefixes, typically
2521 @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are
2522 called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see
2523 such symbols when debugging, because they are intended for the use of
2524 programs (like compilers) that compose assembler programs, not for your
2525 notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard
2526 such symbols, so you do not normally debug with them.
2528 This option tells @command{@value{AS}} to retain those local symbols
2529 in the object file. Usually if you do this you also tell the linker
2530 @code{@value{LD}} to preserve those symbols.
2533 @section Configuring listing output: @option{--listing}
2535 The listing feature of the assembler can be enabled via the command-line switch
2536 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
2537 hex dump of the corresponding locations in the output object file, and displays
2538 them as a listing file. The format of this listing can be controlled by
2539 directives inside the assembler source (i.e., @code{.list} (@pxref{List}),
2540 @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}),
2541 @code{.psize} (@pxref{Psize}), and
2542 @code{.eject} (@pxref{Eject}) and also by the following switches:
2545 @item --listing-lhs-width=@samp{number}
2546 @kindex --listing-lhs-width
2547 @cindex Width of first line disassembly output
2548 Sets the maximum width, in words, of the first line of the hex byte dump. This
2549 dump appears on the left hand side of the listing output.
2551 @item --listing-lhs-width2=@samp{number}
2552 @kindex --listing-lhs-width2
2553 @cindex Width of continuation lines of disassembly output
2554 Sets the maximum width, in words, of any further lines of the hex byte dump for
2555 a given input source line. If this value is not specified, it defaults to being
2556 the same as the value specified for @samp{--listing-lhs-width}. If neither
2557 switch is used the default is to one.
2559 @item --listing-rhs-width=@samp{number}
2560 @kindex --listing-rhs-width
2561 @cindex Width of source line output
2562 Sets the maximum width, in characters, of the source line that is displayed
2563 alongside the hex dump. The default value for this parameter is 100. The
2564 source line is displayed on the right hand side of the listing output.
2566 @item --listing-cont-lines=@samp{number}
2567 @kindex --listing-cont-lines
2568 @cindex Maximum number of continuation lines
2569 Sets the maximum number of continuation lines of hex dump that will be
2570 displayed for a given single line of source input. The default value is 4.
2574 @section Assemble in MRI Compatibility Mode: @option{-M}
2577 @cindex MRI compatibility mode
2578 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
2579 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
2580 compatible with the @code{ASM68K} assembler from Microtec Research.
2581 The exact nature of the
2582 MRI syntax will not be documented here; see the MRI manuals for more
2583 information. Note in particular that the handling of macros and macro
2584 arguments is somewhat different. The purpose of this option is to permit
2585 assembling existing MRI assembler code using @command{@value{AS}}.
2587 The MRI compatibility is not complete. Certain operations of the MRI assembler
2588 depend upon its object file format, and can not be supported using other object
2589 file formats. Supporting these would require enhancing each object file format
2590 individually. These are:
2593 @item global symbols in common section
2595 The m68k MRI assembler supports common sections which are merged by the linker.
2596 Other object file formats do not support this. @command{@value{AS}} handles
2597 common sections by treating them as a single common symbol. It permits local
2598 symbols to be defined within a common section, but it can not support global
2599 symbols, since it has no way to describe them.
2601 @item complex relocations
2603 The MRI assemblers support relocations against a negated section address, and
2604 relocations which combine the start addresses of two or more sections. These
2605 are not support by other object file formats.
2607 @item @code{END} pseudo-op specifying start address
2609 The MRI @code{END} pseudo-op permits the specification of a start address.
2610 This is not supported by other object file formats. The start address may
2611 instead be specified using the @option{-e} option to the linker, or in a linker
2614 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
2616 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
2617 name to the output file. This is not supported by other object file formats.
2619 @item @code{ORG} pseudo-op
2621 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
2622 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
2623 which changes the location within the current section. Absolute sections are
2624 not supported by other object file formats. The address of a section may be
2625 assigned within a linker script.
2628 There are some other features of the MRI assembler which are not supported by
2629 @command{@value{AS}}, typically either because they are difficult or because they
2630 seem of little consequence. Some of these may be supported in future releases.
2634 @item EBCDIC strings
2636 EBCDIC strings are not supported.
2638 @item packed binary coded decimal
2640 Packed binary coded decimal is not supported. This means that the @code{DC.P}
2641 and @code{DCB.P} pseudo-ops are not supported.
2643 @item @code{FEQU} pseudo-op
2645 The m68k @code{FEQU} pseudo-op is not supported.
2647 @item @code{NOOBJ} pseudo-op
2649 The m68k @code{NOOBJ} pseudo-op is not supported.
2651 @item @code{OPT} branch control options
2653 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
2654 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
2655 relaxes all branches, whether forward or backward, to an appropriate size, so
2656 these options serve no purpose.
2658 @item @code{OPT} list control options
2660 The following m68k @code{OPT} list control options are ignored: @code{C},
2661 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
2662 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
2664 @item other @code{OPT} options
2666 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
2667 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
2669 @item @code{OPT} @code{D} option is default
2671 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
2672 @code{OPT NOD} may be used to turn it off.
2674 @item @code{XREF} pseudo-op.
2676 The m68k @code{XREF} pseudo-op is ignored.
2681 @section Dependency Tracking: @option{--MD}
2684 @cindex dependency tracking
2687 @command{@value{AS}} can generate a dependency file for the file it creates. This
2688 file consists of a single rule suitable for @code{make} describing the
2689 dependencies of the main source file.
2691 The rule is written to the file named in its argument.
2693 This feature is used in the automatic updating of makefiles.
2695 @node no-pad-sections
2696 @section Output Section Padding
2697 @kindex --no-pad-sections
2698 @cindex output section padding
2699 Normally the assembler will pad the end of each output section up to its
2700 alignment boundary. But this can waste space, which can be significant on
2701 memory constrained targets. So the @option{--no-pad-sections} option will
2702 disable this behaviour.
2705 @section Name the Object File: @option{-o}
2708 @cindex naming object file
2709 @cindex object file name
2710 There is always one object file output when you run @command{@value{AS}}. By
2711 default it has the name @file{a.out}.
2712 You use this option (which takes exactly one filename) to give the
2713 object file a different name.
2715 Whatever the object file is called, @command{@value{AS}} overwrites any
2716 existing file of the same name.
2719 @section Join Data and Text Sections: @option{-R}
2722 @cindex data and text sections, joining
2723 @cindex text and data sections, joining
2724 @cindex joining text and data sections
2725 @cindex merging text and data sections
2726 @option{-R} tells @command{@value{AS}} to write the object file as if all
2727 data-section data lives in the text section. This is only done at
2728 the very last moment: your binary data are the same, but data
2729 section parts are relocated differently. The data section part of
2730 your object file is zero bytes long because all its bytes are
2731 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
2733 When you specify @option{-R} it would be possible to generate shorter
2734 address displacements (because we do not have to cross between text and
2735 data section). We refrain from doing this simply for compatibility with
2736 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
2739 When @command{@value{AS}} is configured for COFF or ELF output,
2740 this option is only useful if you use sections named @samp{.text} and
2745 @option{-R} is not supported for any of the HPPA targets. Using
2746 @option{-R} generates a warning from @command{@value{AS}}.
2750 @section Display Assembly Statistics: @option{--statistics}
2752 @kindex --statistics
2753 @cindex statistics, about assembly
2754 @cindex time, total for assembly
2755 @cindex space used, maximum for assembly
2756 Use @samp{--statistics} to display two statistics about the resources used by
2757 @command{@value{AS}}: the maximum amount of space allocated during the assembly
2758 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
2761 @node traditional-format
2762 @section Compatible Output: @option{--traditional-format}
2764 @kindex --traditional-format
2765 For some targets, the output of @command{@value{AS}} is different in some ways
2766 from the output of some existing assembler. This switch requests
2767 @command{@value{AS}} to use the traditional format instead.
2769 For example, it disables the exception frame optimizations which
2770 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
2773 @section Announce Version: @option{-v}
2777 @cindex assembler version
2778 @cindex version of assembler
2779 You can find out what version of as is running by including the
2780 option @samp{-v} (which you can also spell as @samp{-version}) on the
2784 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
2786 @command{@value{AS}} should never give a warning or error message when
2787 assembling compiler output. But programs written by people often
2788 cause @command{@value{AS}} to give a warning that a particular assumption was
2789 made. All such warnings are directed to the standard error file.
2793 @cindex suppressing warnings
2794 @cindex warnings, suppressing
2795 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
2796 This only affects the warning messages: it does not change any particular of
2797 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
2800 @kindex --fatal-warnings
2801 @cindex errors, caused by warnings
2802 @cindex warnings, causing error
2803 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
2804 files that generate warnings to be in error.
2807 @cindex warnings, switching on
2808 You can switch these options off again by specifying @option{--warn}, which
2809 causes warnings to be output as usual.
2812 @section Generate Object File in Spite of Errors: @option{-Z}
2813 @cindex object file, after errors
2814 @cindex errors, continuing after
2815 After an error message, @command{@value{AS}} normally produces no output. If for
2816 some reason you are interested in object file output even after
2817 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
2818 option. If there are any errors, @command{@value{AS}} continues anyways, and
2819 writes an object file after a final warning message of the form @samp{@var{n}
2820 errors, @var{m} warnings, generating bad object file.}
2825 @cindex machine-independent syntax
2826 @cindex syntax, machine-independent
2827 This chapter describes the machine-independent syntax allowed in a
2828 source file. @command{@value{AS}} syntax is similar to what many other
2829 assemblers use; it is inspired by the BSD 4.2
2834 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
2838 * Preprocessing:: Preprocessing
2839 * Whitespace:: Whitespace
2840 * Comments:: Comments
2841 * Symbol Intro:: Symbols
2842 * Statements:: Statements
2843 * Constants:: Constants
2847 @section Preprocessing
2849 @cindex preprocessing
2850 The @command{@value{AS}} internal preprocessor:
2852 @cindex whitespace, removed by preprocessor
2854 adjusts and removes extra whitespace. It leaves one space or tab before
2855 the keywords on a line, and turns any other whitespace on the line into
2858 @cindex comments, removed by preprocessor
2860 removes all comments, replacing them with a single space, or an
2861 appropriate number of newlines.
2863 @cindex constants, converted by preprocessor
2865 converts character constants into the appropriate numeric values.
2868 It does not do macro processing, include file handling, or
2869 anything else you may get from your C compiler's preprocessor. You can
2870 do include file processing with the @code{.include} directive
2871 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2872 to get other ``CPP'' style preprocessing by giving the input file a
2873 @samp{.S} suffix. @url{https://gcc.gnu.org/onlinedocs/gcc/Overall-Options.html#Overall-Options,
2874 See the 'Options Controlling the Kind of Output' section of the GCC manual for
2877 Excess whitespace, comments, and character constants
2878 cannot be used in the portions of the input text that are not
2881 @cindex turning preprocessing on and off
2882 @cindex preprocessing, turning on and off
2885 If the first line of an input file is @code{#NO_APP} or if you use the
2886 @samp{-f} option, whitespace and comments are not removed from the input file.
2887 Within an input file, you can ask for whitespace and comment removal in
2888 specific portions of the by putting a line that says @code{#APP} before the
2889 text that may contain whitespace or comments, and putting a line that says
2890 @code{#NO_APP} after this text. This feature is mainly intend to support
2891 @code{asm} statements in compilers whose output is otherwise free of comments
2898 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2899 Whitespace is used to separate symbols, and to make programs neater for
2900 people to read. Unless within character constants
2901 (@pxref{Characters,,Character Constants}), any whitespace means the same
2902 as exactly one space.
2908 There are two ways of rendering comments to @command{@value{AS}}. In both
2909 cases the comment is equivalent to one space.
2911 Anything from @samp{/*} through the next @samp{*/} is a comment.
2912 This means you may not nest these comments.
2916 The only way to include a newline ('\n') in a comment
2917 is to use this sort of comment.
2920 /* This sort of comment does not nest. */
2923 @cindex line comment character
2924 Anything from a @dfn{line comment} character up to the next newline is
2925 considered a comment and is ignored. The line comment character is target
2926 specific, and some targets multiple comment characters. Some targets also have
2927 line comment characters that only work if they are the first character on a
2928 line. Some targets use a sequence of two characters to introduce a line
2929 comment. Some targets can also change their line comment characters depending
2930 upon command-line options that have been used. For more details see the
2931 @emph{Syntax} section in the documentation for individual targets.
2933 If the line comment character is the hash sign (@samp{#}) then it still has the
2934 special ability to enable and disable preprocessing (@pxref{Preprocessing}) and
2935 to specify logical line numbers:
2938 @cindex lines starting with @code{#}
2939 @cindex logical line numbers
2940 To be compatible with past assemblers, lines that begin with @samp{#} have a
2941 special interpretation. Following the @samp{#} should be an absolute
2942 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2943 line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a
2944 new logical file name. The rest of the line, if any, should be whitespace.
2946 If the first non-whitespace characters on the line are not numeric,
2947 the line is ignored. (Just like a comment.)
2950 # This is an ordinary comment.
2951 # 42-6 "new_file_name" # New logical file name
2952 # This is logical line # 36.
2954 This feature is deprecated, and may disappear from future versions
2955 of @command{@value{AS}}.
2960 @cindex characters used in symbols
2961 @ifclear SPECIAL-SYMS
2962 A @dfn{symbol} is one or more characters chosen from the set of all
2963 letters (both upper and lower case), digits and the three characters
2969 A @dfn{symbol} is one or more characters chosen from the set of all
2970 letters (both upper and lower case), digits and the three characters
2971 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2977 On most machines, you can also use @code{$} in symbol names; exceptions
2978 are noted in @ref{Machine Dependencies}.
2980 No symbol may begin with a digit. Case is significant.
2981 There is no length limit; all characters are significant. Multibyte characters
2982 are supported, but note that the setting of the
2983 @option{--multibyte-handling} option might prevent their use. Symbols
2984 are delimited by characters not in that set, or by the beginning of a file
2985 (since the source program must end with a newline, the end of a file is not a
2986 possible symbol delimiter). @xref{Symbols}.
2988 Symbol names may also be enclosed in double quote @code{"} characters. In such
2989 cases any characters are allowed, except for the NUL character. If a double
2990 quote character is to be included in the symbol name it must be preceded by a
2991 backslash @code{\} character.
2992 @cindex length of symbols
2997 @cindex statements, structure of
2998 @cindex line separator character
2999 @cindex statement separator character
3001 A @dfn{statement} ends at a newline character (@samp{\n}) or a
3002 @dfn{line separator character}. The line separator character is target
3003 specific and described in the @emph{Syntax} section of each
3004 target's documentation. Not all targets support a line separator character.
3005 The newline or line separator character is considered to be part of the
3006 preceding statement. Newlines and separators within character constants are an
3007 exception: they do not end statements.
3009 @cindex newline, required at file end
3010 @cindex EOF, newline must precede
3011 It is an error to end any statement with end-of-file: the last
3012 character of any input file should be a newline.@refill
3014 An empty statement is allowed, and may include whitespace. It is ignored.
3016 @cindex instructions and directives
3017 @cindex directives and instructions
3018 @c "key symbol" is not used elsewhere in the document; seems pedantic to
3019 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
3021 A statement begins with zero or more labels, optionally followed by a
3022 key symbol which determines what kind of statement it is. The key
3023 symbol determines the syntax of the rest of the statement. If the
3024 symbol begins with a dot @samp{.} then the statement is an assembler
3025 directive: typically valid for any computer. If the symbol begins with
3026 a letter the statement is an assembly language @dfn{instruction}: it
3027 assembles into a machine language instruction.
3029 Different versions of @command{@value{AS}} for different computers
3030 recognize different instructions. In fact, the same symbol may
3031 represent a different instruction in a different computer's assembly
3035 @cindex @code{:} (label)
3036 @cindex label (@code{:})
3037 A label is a symbol immediately followed by a colon (@code{:}).
3038 Whitespace before a label or after a colon is permitted, but you may not
3039 have whitespace between a label's symbol and its colon. @xref{Labels}.
3042 For HPPA targets, labels need not be immediately followed by a colon, but
3043 the definition of a label must begin in column zero. This also implies that
3044 only one label may be defined on each line.
3048 label: .directive followed by something
3049 another_label: # This is an empty statement.
3050 instruction operand_1, operand_2, @dots{}
3057 A constant is a number, written so that its value is known by
3058 inspection, without knowing any context. Like this:
3061 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
3062 .ascii "Ring the bell\7" # A string constant.
3063 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
3064 .float 0f-314159265358979323846264338327\
3065 95028841971.693993751E-40 # - pi, a flonum.
3070 * Characters:: Character Constants
3071 * Numbers:: Number Constants
3075 @subsection Character Constants
3077 @cindex character constants
3078 @cindex constants, character
3079 There are two kinds of character constants. A @dfn{character} stands
3080 for one character in one byte and its value may be used in
3081 numeric expressions. String constants (properly called string
3082 @emph{literals}) are potentially many bytes and their values may not be
3083 used in arithmetic expressions.
3087 * Chars:: Characters
3091 @subsubsection Strings
3093 @cindex string constants
3094 @cindex constants, string
3095 A @dfn{string} is written between double-quotes. It may contain
3096 double-quotes or null characters. The way to get special characters
3097 into a string is to @dfn{escape} these characters: precede them with
3098 a backslash @samp{\} character. For example @samp{\\} represents
3099 one backslash: the first @code{\} is an escape which tells
3100 @command{@value{AS}} to interpret the second character literally as a backslash
3101 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
3102 escape character). The complete list of escapes follows.
3104 @cindex escape codes, character
3105 @cindex character escape codes
3106 @c NOTE: Cindex entries must not start with a backlash character.
3107 @c NOTE: This confuses the pdf2texi script when it is creating the
3108 @c NOTE: index based upon the first character and so it generates:
3109 @c NOTE: \initial {\\}
3110 @c NOTE: which then results in the error message:
3111 @c NOTE: Argument of \\ has an extra }.
3112 @c NOTE: So in the index entries below a space character has been
3113 @c NOTE: prepended to avoid this problem.
3116 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
3118 @cindex @code{ \b} (backspace character)
3119 @cindex backspace (@code{\b})
3121 Mnemonic for backspace; for ASCII this is octal code 010.
3124 @c Mnemonic for EOText; for ASCII this is octal code 004.
3126 @cindex @code{ \f} (formfeed character)
3127 @cindex formfeed (@code{\f})
3129 Mnemonic for FormFeed; for ASCII this is octal code 014.
3131 @cindex @code{ \n} (newline character)
3132 @cindex newline (@code{\n})
3134 Mnemonic for newline; for ASCII this is octal code 012.
3137 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
3139 @cindex @code{ \r} (carriage return character)
3140 @cindex carriage return (@code{backslash-r})
3142 Mnemonic for carriage-Return; for ASCII this is octal code 015.
3145 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
3146 @c other assemblers.
3148 @cindex @code{ \t} (tab)
3149 @cindex tab (@code{\t})
3151 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
3154 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
3155 @c @item \x @var{digit} @var{digit} @var{digit}
3156 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
3158 @cindex @code{ \@var{ddd}} (octal character code)
3159 @cindex octal character code (@code{\@var{ddd}})
3160 @item \ @var{digit} @var{digit} @var{digit}
3161 An octal character code. The numeric code is 3 octal digits.
3162 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
3163 for example, @code{\008} has the value 010, and @code{\009} the value 011.
3165 @cindex @code{ \@var{xd...}} (hex character code)
3166 @cindex hex character code (@code{\@var{xd...}})
3167 @item \@code{x} @var{hex-digits...}
3168 A hex character code. All trailing hex digits are combined. Either upper or
3169 lower case @code{x} works.
3171 @cindex @code{ \\} (@samp{\} character)
3172 @cindex backslash (@code{\\})
3174 Represents one @samp{\} character.
3177 @c Represents one @samp{'} (accent acute) character.
3178 @c This is needed in single character literals
3179 @c (@xref{Characters,,Character Constants}.) to represent
3182 @cindex @code{ \"} (doublequote character)
3183 @cindex doublequote (@code{\"})
3185 Represents one @samp{"} character. Needed in strings to represent
3186 this character, because an unescaped @samp{"} would end the string.
3188 @item \ @var{anything-else}
3189 Any other character when escaped by @kbd{\} gives a warning, but
3190 assembles as if the @samp{\} was not present. The idea is that if
3191 you used an escape sequence you clearly didn't want the literal
3192 interpretation of the following character. However @command{@value{AS}} has no
3193 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
3194 code and warns you of the fact.
3197 Which characters are escapable, and what those escapes represent,
3198 varies widely among assemblers. The current set is what we think
3199 the BSD 4.2 assembler recognizes, and is a subset of what most C
3200 compilers recognize. If you are in doubt, do not use an escape
3204 @subsubsection Characters
3206 @cindex single character constant
3207 @cindex character, single
3208 @cindex constant, single character
3209 A single character may be written as a single quote immediately followed by
3210 that character. Some backslash escapes apply to characters, @code{\b},
3211 @code{\f}, @code{\n}, @code{\r}, @code{\t}, and @code{\"} with the same meaning
3212 as for strings, plus @code{\'} for a single quote. So if you want to write the
3213 character backslash, you must write @kbd{'\\} where the first @code{\} escapes
3214 the second @code{\}. As you can see, the quote is an acute accent, not a grave
3217 @ifclear abnormal-separator
3218 (or semicolon @samp{;})
3220 @ifset abnormal-separator
3222 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
3227 immediately following an acute accent is taken as a literal character
3228 and does not count as the end of a statement. The value of a character
3229 constant in a numeric expression is the machine's byte-wide code for
3230 that character. @command{@value{AS}} assumes your character code is ASCII:
3231 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
3234 @subsection Number Constants
3236 @cindex constants, number
3237 @cindex number constants
3238 @command{@value{AS}} distinguishes three kinds of numbers according to how they
3239 are stored in the target machine. @emph{Integers} are numbers that
3240 would fit into an @code{int} in the C language. @emph{Bignums} are
3241 integers, but they are stored in more than 32 bits. @emph{Flonums}
3242 are floating point numbers, described below.
3245 * Integers:: Integers
3253 @subsubsection Integers
3255 @cindex constants, integer
3257 @cindex binary integers
3258 @cindex integers, binary
3259 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
3260 the binary digits @samp{01}.
3262 @cindex octal integers
3263 @cindex integers, octal
3264 An octal integer is @samp{0} followed by zero or more of the octal
3265 digits (@samp{01234567}).
3267 @cindex decimal integers
3268 @cindex integers, decimal
3269 A decimal integer starts with a non-zero digit followed by zero or
3270 more digits (@samp{0123456789}).
3272 @cindex hexadecimal integers
3273 @cindex integers, hexadecimal
3274 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
3275 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
3277 Integers have the usual values. To denote a negative integer, use
3278 the prefix operator @samp{-} discussed under expressions
3279 (@pxref{Prefix Ops,,Prefix Operators}).
3282 @subsubsection Bignums
3285 @cindex constants, bignum
3286 A @dfn{bignum} has the same syntax and semantics as an integer
3287 except that the number (or its negative) takes more than 32 bits to
3288 represent in binary. The distinction is made because in some places
3289 integers are permitted while bignums are not.
3292 @subsubsection Flonums
3294 @cindex floating point numbers
3295 @cindex constants, floating point
3297 @cindex precision, floating point
3298 A @dfn{flonum} represents a floating point number. The translation is
3299 indirect: a decimal floating point number from the text is converted by
3300 @command{@value{AS}} to a generic binary floating point number of more than
3301 sufficient precision. This generic floating point number is converted
3302 to a particular computer's floating point format (or formats) by a
3303 portion of @command{@value{AS}} specialized to that computer.
3305 A flonum is written by writing (in order)
3310 (@samp{0} is optional on the HPPA.)
3314 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
3316 @kbd{e} is recommended. Case is not important.
3318 @c FIXME: verify if flonum syntax really this vague for most cases
3319 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
3320 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
3323 On the H8/300 and Renesas / SuperH SH architectures, the letter must be
3324 one of the letters @samp{DFPRSX} (in upper or lower case).
3326 On the ARC, the letter must be one of the letters @samp{DFRS}
3327 (in upper or lower case).
3329 On the HPPA architecture, the letter must be @samp{E} (upper case only).
3333 One of the letters @samp{DFRS} (in upper or lower case).
3336 One of the letters @samp{DFPRSX} (in upper or lower case).
3339 The letter @samp{E} (upper case only).
3344 An optional sign: either @samp{+} or @samp{-}.
3347 An optional @dfn{integer part}: zero or more decimal digits.
3350 An optional @dfn{fractional part}: @samp{.} followed by zero
3351 or more decimal digits.
3354 An optional exponent, consisting of:
3358 An @samp{E} or @samp{e}.
3359 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
3360 @c principle this can perfectly well be different on different targets.
3362 Optional sign: either @samp{+} or @samp{-}.
3364 One or more decimal digits.
3369 At least one of the integer part or the fractional part must be
3370 present. The floating point number has the usual base-10 value.
3372 @command{@value{AS}} does all processing using integers. Flonums are computed
3373 independently of any floating point hardware in the computer running
3374 @command{@value{AS}}.
3377 @chapter Sections and Relocation
3382 * Secs Background:: Background
3383 * Ld Sections:: Linker Sections
3384 * As Sections:: Assembler Internal Sections
3385 * Sub-Sections:: Sub-Sections
3389 @node Secs Background
3392 Roughly, a section is a range of addresses, with no gaps; all data
3393 ``in'' those addresses is treated the same for some particular purpose.
3394 For example there may be a ``read only'' section.
3396 @cindex linker, and assembler
3397 @cindex assembler, and linker
3398 The linker @code{@value{LD}} reads many object files (partial programs) and
3399 combines their contents to form a runnable program. When @command{@value{AS}}
3400 emits an object file, the partial program is assumed to start at address 0.
3401 @code{@value{LD}} assigns the final addresses for the partial program, so that
3402 different partial programs do not overlap. This is actually an
3403 oversimplification, but it suffices to explain how @command{@value{AS}} uses
3406 @code{@value{LD}} moves blocks of bytes of your program to their run-time
3407 addresses. These blocks slide to their run-time addresses as rigid
3408 units; their length does not change and neither does the order of bytes
3409 within them. Such a rigid unit is called a @emph{section}. Assigning
3410 run-time addresses to sections is called @dfn{relocation}. It includes
3411 the task of adjusting mentions of object-file addresses so they refer to
3412 the proper run-time addresses.
3414 For the H8/300, and for the Renesas / SuperH SH,
3415 @command{@value{AS}} pads sections if needed to
3416 ensure they end on a word (sixteen bit) boundary.
3419 @cindex standard assembler sections
3420 An object file written by @command{@value{AS}} has at least three sections, any
3421 of which may be empty. These are named @dfn{text}, @dfn{data} and
3426 When it generates COFF or ELF output,
3428 @command{@value{AS}} can also generate whatever other named sections you specify
3429 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
3430 If you do not use any directives that place output in the @samp{.text}
3431 or @samp{.data} sections, these sections still exist, but are empty.
3436 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
3438 @command{@value{AS}} can also generate whatever other named sections you
3439 specify using the @samp{.space} and @samp{.subspace} directives. See
3440 @cite{HP9000 Series 800 Assembly Language Reference Manual}
3441 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
3442 assembler directives.
3445 Additionally, @command{@value{AS}} uses different names for the standard
3446 text, data, and bss sections when generating SOM output. Program text
3447 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
3448 BSS into @samp{$BSS$}.
3452 Within the object file, the text section starts at address @code{0}, the
3453 data section follows, and the bss section follows the data section.
3456 When generating either SOM or ELF output files on the HPPA, the text
3457 section starts at address @code{0}, the data section at address
3458 @code{0x4000000}, and the bss section follows the data section.
3461 To let @code{@value{LD}} know which data changes when the sections are
3462 relocated, and how to change that data, @command{@value{AS}} also writes to the
3463 object file details of the relocation needed. To perform relocation
3464 @code{@value{LD}} must know, each time an address in the object
3468 Where in the object file is the beginning of this reference to
3471 How long (in bytes) is this reference?
3473 Which section does the address refer to? What is the numeric value of
3475 (@var{address}) @minus{} (@var{start-address of section})?
3478 Is the reference to an address ``Program-Counter relative''?
3481 @cindex addresses, format of
3482 @cindex section-relative addressing
3483 In fact, every address @command{@value{AS}} ever uses is expressed as
3485 (@var{section}) + (@var{offset into section})
3488 Further, most expressions @command{@value{AS}} computes have this section-relative
3491 (For some object formats, such as SOM for the HPPA, some expressions are
3492 symbol-relative instead.)
3495 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
3496 @var{N} into section @var{secname}.''
3498 Apart from text, data and bss sections you need to know about the
3499 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
3500 addresses in the absolute section remain unchanged. For example, address
3501 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
3502 @code{@value{LD}}. Although the linker never arranges two partial programs'
3503 data sections with overlapping addresses after linking, @emph{by definition}
3504 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
3505 part of a program is always the same address when the program is running as
3506 address @code{@{absolute@ 239@}} in any other part of the program.
3508 The idea of sections is extended to the @dfn{undefined} section. Any
3509 address whose section is unknown at assembly time is by definition
3510 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
3511 Since numbers are always defined, the only way to generate an undefined
3512 address is to mention an undefined symbol. A reference to a named
3513 common block would be such a symbol: its value is unknown at assembly
3514 time so it has section @emph{undefined}.
3516 By analogy the word @emph{section} is used to describe groups of sections in
3517 the linked program. @code{@value{LD}} puts all partial programs' text
3518 sections in contiguous addresses in the linked program. It is
3519 customary to refer to the @emph{text section} of a program, meaning all
3520 the addresses of all partial programs' text sections. Likewise for
3521 data and bss sections.
3523 Some sections are manipulated by @code{@value{LD}}; others are invented for
3524 use of @command{@value{AS}} and have no meaning except during assembly.
3527 @section Linker Sections
3528 @code{@value{LD}} deals with just four kinds of sections, summarized below.
3533 @cindex named sections
3534 @cindex sections, named
3535 @item named sections
3538 @cindex text section
3539 @cindex data section
3543 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
3544 separate but equal sections. Anything you can say of one section is
3547 When the program is running, however, it is
3548 customary for the text section to be unalterable. The
3549 text section is often shared among processes: it contains
3550 instructions, constants and the like. The data section of a running
3551 program is usually alterable: for example, C variables would be stored
3552 in the data section.
3557 This section contains zeroed bytes when your program begins running. It
3558 is used to hold uninitialized variables or common storage. The length of
3559 each partial program's bss section is important, but because it starts
3560 out containing zeroed bytes there is no need to store explicit zero
3561 bytes in the object file. The bss section was invented to eliminate
3562 those explicit zeros from object files.
3564 @cindex absolute section
3565 @item absolute section
3566 Address 0 of this section is always ``relocated'' to runtime address 0.
3567 This is useful if you want to refer to an address that @code{@value{LD}} must
3568 not change when relocating. In this sense we speak of absolute
3569 addresses being ``unrelocatable'': they do not change during relocation.
3571 @cindex undefined section
3572 @item undefined section
3573 This ``section'' is a catch-all for address references to objects not in
3574 the preceding sections.
3575 @c FIXME: ref to some other doc on obj-file formats could go here.
3578 @cindex relocation example
3579 An idealized example of three relocatable sections follows.
3581 The example uses the traditional section names @samp{.text} and @samp{.data}.
3583 Memory addresses are on the horizontal axis.
3587 @c END TEXI2ROFF-KILL
3590 partial program # 1: |ttttt|dddd|00|
3597 partial program # 2: |TTT|DDD|000|
3600 +--+---+-----+--+----+---+-----+~~
3601 linked program: | |TTT|ttttt| |dddd|DDD|00000|
3602 +--+---+-----+--+----+---+-----+~~
3604 addresses: 0 @dots{}
3611 \line{\it Partial program \#1: \hfil}
3612 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3613 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
3615 \line{\it Partial program \#2: \hfil}
3616 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3617 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
3619 \line{\it linked program: \hfil}
3620 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
3621 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
3622 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
3623 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
3625 \line{\it addresses: \hfil}
3629 @c END TEXI2ROFF-KILL
3632 @section Assembler Internal Sections
3634 @cindex internal assembler sections
3635 @cindex sections in messages, internal
3636 These sections are meant only for the internal use of @command{@value{AS}}. They
3637 have no meaning at run-time. You do not really need to know about these
3638 sections for most purposes; but they can be mentioned in @command{@value{AS}}
3639 warning messages, so it might be helpful to have an idea of their
3640 meanings to @command{@value{AS}}. These sections are used to permit the
3641 value of every expression in your assembly language program to be a
3642 section-relative address.
3645 @cindex assembler internal logic error
3646 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
3647 An internal assembler logic error has been found. This means there is a
3648 bug in the assembler.
3650 @cindex expr (internal section)
3652 The assembler stores complex expression internally as combinations of
3653 symbols. When it needs to represent an expression as a symbol, it puts
3654 it in the expr section.
3656 @c FIXME item transfer[t] vector preload
3657 @c FIXME item transfer[t] vector postload
3658 @c FIXME item register
3662 @section Sub-Sections
3664 @cindex numbered subsections
3665 @cindex grouping data
3671 fall into two sections: text and data.
3673 You may have separate groups of
3675 data in named sections
3679 data in named sections
3685 that you want to end up near to each other in the object file, even though they
3686 are not contiguous in the assembler source. @command{@value{AS}} allows you to
3687 use @dfn{subsections} for this purpose. Within each section, there can be
3688 numbered subsections with values from 0 to 8192. Objects assembled into the
3689 same subsection go into the object file together with other objects in the same
3690 subsection. For example, a compiler might want to store constants in the text
3691 section, but might not want to have them interspersed with the program being
3692 assembled. In this case, the compiler could issue a @samp{.text 0} before each
3693 section of code being output, and a @samp{.text 1} before each group of
3694 constants being output.
3696 Subsections are optional. If you do not use subsections, everything
3697 goes in subsection number zero.
3700 Each subsection is zero-padded up to a multiple of four bytes.
3701 (Subsections may be padded a different amount on different flavors
3702 of @command{@value{AS}}.)
3706 On the H8/300 platform, each subsection is zero-padded to a word
3707 boundary (two bytes).
3708 The same is true on the Renesas SH.
3712 Subsections appear in your object file in numeric order, lowest numbered
3713 to highest. (All this to be compatible with other people's assemblers.)
3714 The object file contains no representation of subsections; @code{@value{LD}} and
3715 other programs that manipulate object files see no trace of them.
3716 They just see all your text subsections as a text section, and all your
3717 data subsections as a data section.
3719 To specify which subsection you want subsequent statements assembled
3720 into, use a numeric argument to specify it, in a @samp{.text
3721 @var{expression}} or a @samp{.data @var{expression}} statement.
3724 When generating COFF output, you
3729 can also use an extra subsection
3730 argument with arbitrary named sections: @samp{.section @var{name},
3735 When generating ELF output, you
3740 can also use the @code{.subsection} directive (@pxref{SubSection})
3741 to specify a subsection: @samp{.subsection @var{expression}}.
3743 @var{Expression} should be an absolute expression
3744 (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0}
3745 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3746 begins in @code{text 0}. For instance:
3748 .text 0 # The default subsection is text 0 anyway.
3749 .ascii "This lives in the first text subsection. *"
3751 .ascii "But this lives in the second text subsection."
3753 .ascii "This lives in the data section,"
3754 .ascii "in the first data subsection."
3756 .ascii "This lives in the first text section,"
3757 .ascii "immediately following the asterisk (*)."
3760 Each section has a @dfn{location counter} incremented by one for every byte
3761 assembled into that section. Because subsections are merely a convenience
3762 restricted to @command{@value{AS}} there is no concept of a subsection location
3763 counter. There is no way to directly manipulate a location counter---but the
3764 @code{.align} directive changes it, and any label definition captures its
3765 current value. The location counter of the section where statements are being
3766 assembled is said to be the @dfn{active} location counter.
3769 @section bss Section
3772 @cindex common variable storage
3773 The bss section is used for local common variable storage.
3774 You may allocate address space in the bss section, but you may
3775 not dictate data to load into it before your program executes. When
3776 your program starts running, all the contents of the bss
3777 section are zeroed bytes.
3779 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3780 @ref{Lcomm,,@code{.lcomm}}.
3782 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3783 another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}.
3786 When assembling for a target which supports multiple sections, such as ELF or
3787 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3788 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3789 section. Typically the section will only contain symbol definitions and
3790 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3797 Symbols are a central concept: the programmer uses symbols to name
3798 things, the linker uses symbols to link, and the debugger uses symbols
3802 @cindex debuggers, and symbol order
3803 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3804 the same order they were declared. This may break some debuggers.
3809 * Setting Symbols:: Giving Symbols Other Values
3810 * Symbol Names:: Symbol Names
3811 * Dot:: The Special Dot Symbol
3812 * Symbol Attributes:: Symbol Attributes
3819 A @dfn{label} is written as a symbol immediately followed by a colon
3820 @samp{:}. The symbol then represents the current value of the
3821 active location counter, and is, for example, a suitable instruction
3822 operand. You are warned if you use the same symbol to represent two
3823 different locations: the first definition overrides any other
3827 On the HPPA, the usual form for a label need not be immediately followed by a
3828 colon, but instead must start in column zero. Only one label may be defined on
3829 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3830 provides a special directive @code{.label} for defining labels more flexibly.
3833 @node Setting Symbols
3834 @section Giving Symbols Other Values
3836 @cindex assigning values to symbols
3837 @cindex symbol values, assigning
3838 A symbol can be given an arbitrary value by writing a symbol, followed
3839 by an equals sign @samp{=}, followed by an expression
3840 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3841 directive. @xref{Set,,@code{.set}}. In the same way, using a double
3842 equals sign @samp{=}@samp{=} here represents an equivalent of the
3843 @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}.
3846 Blackfin does not support symbol assignment with @samp{=}.
3850 @section Symbol Names
3852 @cindex symbol names
3853 @cindex names, symbol
3854 @ifclear SPECIAL-SYMS
3855 Symbol names begin with a letter or with one of @samp{._}. On most
3856 machines, you can also use @code{$} in symbol names; exceptions are
3857 noted in @ref{Machine Dependencies}. That character may be followed by any
3858 string of digits, letters, dollar signs (unless otherwise noted for a
3859 particular target machine), and underscores.
3863 Symbol names begin with a letter or with one of @samp{._}. On the
3864 Renesas SH you can also use @code{$} in symbol names. That
3865 character may be followed by any string of digits, letters, dollar signs (save
3866 on the H8/300), and underscores.
3870 Case of letters is significant: @code{foo} is a different symbol name
3873 Symbol names do not start with a digit. An exception to this rule is made for
3874 Local Labels. See below.
3876 Multibyte characters are supported, but note that the setting of the
3877 @option{multibyte-handling} option might prevent their use.
3878 To generate a symbol name containing
3879 multibyte characters enclose it within double quotes and use escape codes. cf
3880 @xref{Strings}. Generating a multibyte symbol name from a label is not
3881 currently supported.
3883 Since multibyte symbol names are unusual, and could possibly be used
3884 maliciously, @command{@value{AS}} provides a command line option
3885 (@option{--multibyte-handling=warn-sym-only}) which can be used to generate a
3886 warning message whenever a symbol name containing multibyte characters is defined.
3888 Each symbol has exactly one name. Each name in an assembly language program
3889 refers to exactly one symbol. You may use that symbol name any number of times
3892 @subheading Local Symbol Names
3894 @cindex local symbol names
3895 @cindex symbol names, local
3896 A local symbol is any symbol beginning with certain local label prefixes.
3897 By default, the local label prefix is @samp{.L} for ELF systems or
3898 @samp{L} for traditional a.out systems, but each target may have its own
3899 set of local label prefixes.
3901 On the HPPA local symbols begin with @samp{L$}.
3904 Local symbols are defined and used within the assembler, but they are
3905 normally not saved in object files. Thus, they are not visible when debugging.
3906 You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols})
3907 to retain the local symbols in the object files.
3909 @subheading Local Labels
3911 @cindex local labels
3912 @cindex temporary symbol names
3913 @cindex symbol names, temporary
3914 Local labels are different from local symbols. Local labels help compilers and
3915 programmers use names temporarily. They create symbols which are guaranteed to
3916 be unique over the entire scope of the input source code and which can be
3917 referred to by a simple notation. To define a local label, write a label of
3918 the form @samp{@b{N}:} (where @b{N} represents any non-negative integer).
3919 To refer to the most recent previous definition of that label write
3920 @samp{@b{N}b}, using the same number as when you defined the label. To refer
3921 to the next definition of a local label, write @samp{@b{N}f}. The @samp{b}
3922 stands for ``backwards'' and the @samp{f} stands for ``forwards''.
3924 There is no restriction on how you can use these labels, and you can reuse them
3925 too. So that it is possible to repeatedly define the same local label (using
3926 the same number @samp{@b{N}}), although you can only refer to the most recently
3927 defined local label of that number (for a backwards reference) or the next
3928 definition of a specific local label for a forward reference. It is also worth
3929 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3930 implemented in a slightly more efficient manner than the others.
3941 Which is the equivalent of:
3944 label_1: branch label_3
3945 label_2: branch label_1
3946 label_3: branch label_4
3947 label_4: branch label_3
3950 Local label names are only a notational device. They are immediately
3951 transformed into more conventional symbol names before the assembler uses them.
3952 The symbol names are stored in the symbol table, appear in error messages, and
3953 are optionally emitted to the object file. The names are constructed using
3957 @item @emph{local label prefix}
3958 All local symbols begin with the system-specific local label prefix.
3959 Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols
3960 that start with the local label prefix. These labels are
3961 used for symbols you are never intended to see. If you use the
3962 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3963 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3964 you may use them in debugging.
3967 This is the number that was used in the local label definition. So if the
3968 label is written @samp{55:} then the number is @samp{55}.
3971 This unusual character is included so you do not accidentally invent a symbol
3972 of the same name. The character has ASCII value of @samp{\002} (control-B).
3974 @item @emph{ordinal number}
3975 This is a serial number to keep the labels distinct. The first definition of
3976 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3977 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3978 the number @samp{1} and its 15th definition gets @samp{15} as well.
3981 So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and
3982 the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}.
3984 @subheading Dollar Local Labels
3985 @cindex dollar local symbols
3987 On some targets @code{@value{AS}} also supports an even more local form of
3988 local labels called dollar labels. These labels go out of scope (i.e., they
3989 become undefined) as soon as a non-local label is defined. Thus they remain
3990 valid for only a small region of the input source code. Normal local labels,
3991 by contrast, remain in scope for the entire file, or until they are redefined
3992 by another occurrence of the same local label.
3994 Dollar labels are defined in exactly the same way as ordinary local labels,
3995 except that they have a dollar sign suffix to their numeric value, e.g.,
3998 They can also be distinguished from ordinary local labels by their transformed
3999 names which use ASCII character @samp{\001} (control-A) as the magic character
4000 to distinguish them from ordinary labels. For example, the fifth definition of
4001 @samp{6$} may be named @samp{.L6@kbd{C-A}5}.
4004 @section The Special Dot Symbol
4006 @cindex dot (symbol)
4007 @cindex @code{.} (symbol)
4008 @cindex current address
4009 @cindex location counter
4010 The special symbol @samp{.} refers to the current address that
4011 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
4012 .long .} defines @code{melvin} to contain its own address.
4013 Assigning a value to @code{.} is treated the same as a @code{.org}
4015 @ifclear no-space-dir
4016 Thus, the expression @samp{.=.+4} is the same as saying
4020 @node Symbol Attributes
4021 @section Symbol Attributes
4023 @cindex symbol attributes
4024 @cindex attributes, symbol
4025 Every symbol has, as well as its name, the attributes ``Value'' and
4026 ``Type''. Depending on output format, symbols can also have auxiliary
4029 The detailed definitions are in @file{a.out.h}.
4032 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
4033 all these attributes, and probably won't warn you. This makes the
4034 symbol an externally defined symbol, which is generally what you
4038 * Symbol Value:: Value
4039 * Symbol Type:: Type
4041 * a.out Symbols:: Symbol Attributes: @code{a.out}
4044 * COFF Symbols:: Symbol Attributes for COFF
4047 * SOM Symbols:: Symbol Attributes for SOM
4054 @cindex value of a symbol
4055 @cindex symbol value
4056 The value of a symbol is (usually) 32 bits. For a symbol which labels a
4057 location in the text, data, bss or absolute sections the value is the
4058 number of addresses from the start of that section to the label.
4059 Naturally for text, data and bss sections the value of a symbol changes
4060 as @code{@value{LD}} changes section base addresses during linking. Absolute
4061 symbols' values do not change during linking: that is why they are
4064 The value of an undefined symbol is treated in a special way. If it is
4065 0 then the symbol is not defined in this assembler source file, and
4066 @code{@value{LD}} tries to determine its value from other files linked into the
4067 same program. You make this kind of symbol simply by mentioning a symbol
4068 name without defining it. A non-zero value represents a @code{.comm}
4069 common declaration. The value is how much common storage to reserve, in
4070 bytes (addresses). The symbol refers to the first address of the
4076 @cindex type of a symbol
4078 The type attribute of a symbol contains relocation (section)
4079 information, any flag settings indicating that a symbol is external, and
4080 (optionally), other information for linkers and debuggers. The exact
4081 format depends on the object-code output format in use.
4085 @subsection Symbol Attributes: @code{a.out}
4087 @cindex @code{a.out} symbol attributes
4088 @cindex symbol attributes, @code{a.out}
4091 * Symbol Desc:: Descriptor
4092 * Symbol Other:: Other
4096 @subsubsection Descriptor
4098 @cindex descriptor, of @code{a.out} symbol
4099 This is an arbitrary 16-bit value. You may establish a symbol's
4100 descriptor value by using a @code{.desc} statement
4101 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
4102 @command{@value{AS}}.
4105 @subsubsection Other
4107 @cindex other attribute, of @code{a.out} symbol
4108 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
4113 @subsection Symbol Attributes for COFF
4115 @cindex COFF symbol attributes
4116 @cindex symbol attributes, COFF
4118 The COFF format supports a multitude of auxiliary symbol attributes;
4119 like the primary symbol attributes, they are set between @code{.def} and
4120 @code{.endef} directives.
4122 @subsubsection Primary Attributes
4124 @cindex primary attributes, COFF symbols
4125 The symbol name is set with @code{.def}; the value and type,
4126 respectively, with @code{.val} and @code{.type}.
4128 @subsubsection Auxiliary Attributes
4130 @cindex auxiliary attributes, COFF symbols
4131 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
4132 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
4133 table information for COFF.
4138 @subsection Symbol Attributes for SOM
4140 @cindex SOM symbol attributes
4141 @cindex symbol attributes, SOM
4143 The SOM format for the HPPA supports a multitude of symbol attributes set with
4144 the @code{.EXPORT} and @code{.IMPORT} directives.
4146 The attributes are described in @cite{HP9000 Series 800 Assembly
4147 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
4148 @code{EXPORT} assembler directive documentation.
4152 @chapter Expressions
4156 @cindex numeric values
4157 An @dfn{expression} specifies an address or numeric value.
4158 Whitespace may precede and/or follow an expression.
4160 The result of an expression must be an absolute number, or else an offset into
4161 a particular section. If an expression is not absolute, and there is not
4162 enough information when @command{@value{AS}} sees the expression to know its
4163 section, a second pass over the source program might be necessary to interpret
4164 the expression---but the second pass is currently not implemented.
4165 @command{@value{AS}} aborts with an error message in this situation.
4168 * Empty Exprs:: Empty Expressions
4169 * Integer Exprs:: Integer Expressions
4173 @section Empty Expressions
4175 @cindex empty expressions
4176 @cindex expressions, empty
4177 An empty expression has no value: it is just whitespace or null.
4178 Wherever an absolute expression is required, you may omit the
4179 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
4180 is compatible with other assemblers.
4183 @section Integer Expressions
4185 @cindex integer expressions
4186 @cindex expressions, integer
4187 An @dfn{integer expression} is one or more @emph{arguments} delimited
4188 by @emph{operators}.
4191 * Arguments:: Arguments
4192 * Operators:: Operators
4193 * Prefix Ops:: Prefix Operators
4194 * Infix Ops:: Infix Operators
4198 @subsection Arguments
4200 @cindex expression arguments
4201 @cindex arguments in expressions
4202 @cindex operands in expressions
4203 @cindex arithmetic operands
4204 @dfn{Arguments} are symbols, numbers or subexpressions. In other
4205 contexts arguments are sometimes called ``arithmetic operands''. In
4206 this manual, to avoid confusing them with the ``instruction operands'' of
4207 the machine language, we use the term ``argument'' to refer to parts of
4208 expressions only, reserving the word ``operand'' to refer only to machine
4209 instruction operands.
4211 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
4212 @var{section} is one of text, data, bss, absolute,
4213 or undefined. @var{NNN} is a signed, 2's complement 32 bit
4216 Numbers are usually integers.
4218 A number can be a flonum or bignum. In this case, you are warned
4219 that only the low order 32 bits are used, and @command{@value{AS}} pretends
4220 these 32 bits are an integer. You may write integer-manipulating
4221 instructions that act on exotic constants, compatible with other
4224 @cindex subexpressions
4225 Subexpressions are a left parenthesis @samp{(} followed by an integer
4226 expression, followed by a right parenthesis @samp{)}; or a prefix
4227 operator followed by an argument.
4230 @subsection Operators
4232 @cindex operators, in expressions
4233 @cindex arithmetic functions
4234 @cindex functions, in expressions
4235 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
4236 operators are followed by an argument. Infix operators appear
4237 between their arguments. Operators may be preceded and/or followed by
4241 @subsection Prefix Operator
4243 @cindex prefix operators
4244 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
4245 one argument, which must be absolute.
4247 @c the tex/end tex stuff surrounding this small table is meant to make
4248 @c it align, on the printed page, with the similar table in the next
4249 @c section (which is inside an enumerate).
4251 \global\advance\leftskip by \itemindent
4256 @dfn{Negation}. Two's complement negation.
4258 @dfn{Complementation}. Bitwise not.
4262 \global\advance\leftskip by -\itemindent
4266 @subsection Infix Operators
4268 @cindex infix operators
4269 @cindex operators, permitted arguments
4270 @dfn{Infix operators} take two arguments, one on either side. Operators
4271 have precedence, but operations with equal precedence are performed left
4272 to right. Apart from @code{+} or @option{-}, both arguments must be
4273 absolute, and the result is absolute.
4276 @cindex operator precedence
4277 @cindex precedence of operators
4284 @dfn{Multiplication}.
4287 @dfn{Division}. Truncation is the same as the C operator @samp{/}
4293 @dfn{Shift Left}. Same as the C operator @samp{<<}.
4296 @dfn{Shift Right}. Same as the C operator @samp{>>}.
4300 Intermediate precedence
4305 @dfn{Bitwise Inclusive Or}.
4311 @dfn{Bitwise Exclusive Or}.
4314 @dfn{Bitwise Or Not}.
4321 @cindex addition, permitted arguments
4322 @cindex plus, permitted arguments
4323 @cindex arguments for addition
4325 @dfn{Addition}. If either argument is absolute, the result has the section of
4326 the other argument. You may not add together arguments from different
4329 @cindex subtraction, permitted arguments
4330 @cindex minus, permitted arguments
4331 @cindex arguments for subtraction
4333 @dfn{Subtraction}. If the right argument is absolute, the
4334 result has the section of the left argument.
4335 If both arguments are in the same section, the result is absolute.
4336 You may not subtract arguments from different sections.
4337 @c FIXME is there still something useful to say about undefined - undefined ?
4339 @cindex comparison expressions
4340 @cindex expressions, comparison
4345 @dfn{Is Not Equal To}
4349 @dfn{Is Greater Than}
4351 @dfn{Is Greater Than Or Equal To}
4353 @dfn{Is Less Than Or Equal To}
4355 The comparison operators can be used as infix operators. A true results has a
4356 value of -1 whereas a false result has a value of 0. Note, these operators
4357 perform signed comparisons.
4360 @item Lowest Precedence
4369 These two logical operations can be used to combine the results of sub
4370 expressions. Note, unlike the comparison operators a true result returns a
4371 value of 1 but a false results does still return 0. Also note that the logical
4372 or operator has a slightly lower precedence than logical and.
4377 In short, it's only meaningful to add or subtract the @emph{offsets} in an
4378 address; you can only have a defined section in one of the two arguments.
4381 @chapter Assembler Directives
4383 @cindex directives, machine independent
4384 @cindex pseudo-ops, machine independent
4385 @cindex machine independent directives
4386 All assembler directives have names that begin with a period (@samp{.}).
4387 The names are case insensitive for most targets, and usually written
4390 This chapter discusses directives that are available regardless of the
4391 target machine configuration for the @sc{gnu} assembler.
4393 Some machine configurations provide additional directives.
4394 @xref{Machine Dependencies}.
4397 @ifset machine-directives
4398 @xref{Machine Dependencies}, for additional directives.
4403 * Abort:: @code{.abort}
4405 * ABORT (COFF):: @code{.ABORT}
4408 * Align:: @code{.align [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
4409 * Altmacro:: @code{.altmacro}
4410 * Ascii:: @code{.ascii "@var{string}"}@dots{}
4411 * Asciz:: @code{.asciz "@var{string}"}@dots{}
4412 * Attach_to_group:: @code{.attach_to_group @var{name}}
4413 * Balign:: @code{.balign [@var{abs-expr}[, @var{abs-expr}]]}
4414 * Bss:: @code{.bss @var{subsection}}
4415 * Bundle directives:: @code{.bundle_align_mode @var{abs-expr}}, etc
4416 * Byte:: @code{.byte @var{expressions}}
4417 * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
4418 * Comm:: @code{.comm @var{symbol} , @var{length} }
4419 * Data:: @code{.data @var{subsection}}
4420 * Dc:: @code{.dc[@var{size}] @var{expressions}}
4421 * Dcb:: @code{.dcb[@var{size}] @var{number} [,@var{fill}]}
4422 * Ds:: @code{.ds[@var{size}] @var{number} [,@var{fill}]}
4424 * Def:: @code{.def @var{name}}
4427 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
4433 * Double:: @code{.double @var{flonums}}
4434 * Eject:: @code{.eject}
4435 * Else:: @code{.else}
4436 * Elseif:: @code{.elseif}
4439 * Endef:: @code{.endef}
4442 * Endfunc:: @code{.endfunc}
4443 * Endif:: @code{.endif}
4444 * Equ:: @code{.equ @var{symbol}, @var{expression}}
4445 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
4446 * Eqv:: @code{.eqv @var{symbol}, @var{expression}}
4448 * Error:: @code{.error @var{string}}
4449 * Exitm:: @code{.exitm}
4450 * Extern:: @code{.extern}
4451 * Fail:: @code{.fail}
4452 * File:: @code{.file}
4453 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
4454 * Float:: @code{.float @var{flonums}}
4455 * Func:: @code{.func}
4456 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4458 * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
4459 * Hidden:: @code{.hidden @var{names}}
4462 * hword:: @code{.hword @var{expressions}}
4463 * Ident:: @code{.ident}
4464 * If:: @code{.if @var{absolute expression}}
4465 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4466 * Include:: @code{.include "@var{file}"}
4467 * Int:: @code{.int @var{expressions}}
4469 * Internal:: @code{.internal @var{names}}
4472 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
4473 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
4474 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
4475 * Lflags:: @code{.lflags}
4476 @ifclear no-line-dir
4477 * Line:: @code{.line @var{line-number}}
4480 * Linkonce:: @code{.linkonce [@var{type}]}
4481 * List:: @code{.list}
4482 * Ln:: @code{.ln @var{line-number}}
4483 * Loc:: @code{.loc @var{fileno} @var{lineno}}
4484 * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}}
4486 * Local:: @code{.local @var{names}}
4489 * Long:: @code{.long @var{expressions}}
4491 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
4494 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
4495 * MRI:: @code{.mri @var{val}}
4496 * Noaltmacro:: @code{.noaltmacro}
4497 * Nolist:: @code{.nolist}
4499 * Nops:: @code{.nops @var{size}[, @var{control}]}
4500 * Octa:: @code{.octa @var{bignums}}
4501 * Offset:: @code{.offset @var{loc}}
4502 * Org:: @code{.org @var{new-lc}, @var{fill}}
4503 * P2align:: @code{.p2align [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
4505 * PopSection:: @code{.popsection}
4506 * Previous:: @code{.previous}
4509 * Print:: @code{.print @var{string}}
4511 * Protected:: @code{.protected @var{names}}
4514 * Psize:: @code{.psize @var{lines}, @var{columns}}
4515 * Purgem:: @code{.purgem @var{name}}
4517 * PushSection:: @code{.pushsection @var{name}}
4520 * Quad:: @code{.quad @var{bignums}}
4521 * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
4522 * Rept:: @code{.rept @var{count}}
4523 * Sbttl:: @code{.sbttl "@var{subheading}"}
4525 * Scl:: @code{.scl @var{class}}
4528 * Section:: @code{.section @var{name}[, @var{flags}]}
4531 * Set:: @code{.set @var{symbol}, @var{expression}}
4532 * Short:: @code{.short @var{expressions}}
4533 * Single:: @code{.single @var{flonums}}
4535 * Size:: @code{.size [@var{name} , @var{expression}]}
4537 @ifclear no-space-dir
4538 * Skip:: @code{.skip @var{size} [,@var{fill}]}
4541 * Sleb128:: @code{.sleb128 @var{expressions}}
4542 @ifclear no-space-dir
4543 * Space:: @code{.space @var{size} [,@var{fill}]}
4546 * Stab:: @code{.stabd, .stabn, .stabs}
4549 * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
4550 * Struct:: @code{.struct @var{expression}}
4552 * SubSection:: @code{.subsection}
4553 * Symver:: @code{.symver @var{name},@var{name2@@nodename}[,@var{visibility}]}
4557 * Tag:: @code{.tag @var{structname}}
4560 * Text:: @code{.text @var{subsection}}
4561 * Title:: @code{.title "@var{heading}"}
4563 * Tls_common:: @code{.tls_common @var{symbol}, @var{length}[, @var{alignment}]}
4566 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
4569 * Uleb128:: @code{.uleb128 @var{expressions}}
4571 * Val:: @code{.val @var{addr}}
4575 * Version:: @code{.version "@var{string}"}
4576 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
4577 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
4580 * Warning:: @code{.warning @var{string}}
4581 * Weak:: @code{.weak @var{names}}
4582 * Weakref:: @code{.weakref @var{alias}, @var{symbol}}
4583 * Word:: @code{.word @var{expressions}}
4584 @ifclear no-space-dir
4585 * Zero:: @code{.zero @var{size}}
4587 * 2byte:: @code{.2byte @var{expressions}}
4588 * 4byte:: @code{.4byte @var{expressions}}
4589 * 8byte:: @code{.8byte @var{bignums}}
4590 * Deprecated:: Deprecated Directives
4594 @section @code{.abort}
4596 @cindex @code{abort} directive
4597 @cindex stopping the assembly
4598 This directive stops the assembly immediately. It is for
4599 compatibility with other assemblers. The original idea was that the
4600 assembly language source would be piped into the assembler. If the sender
4601 of the source quit, it could use this directive tells @command{@value{AS}} to
4602 quit also. One day @code{.abort} will not be supported.
4606 @section @code{.ABORT} (COFF)
4608 @cindex @code{ABORT} directive
4609 When producing COFF output, @command{@value{AS}} accepts this directive as a
4610 synonym for @samp{.abort}.
4615 @section @code{.align [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
4617 @cindex padding the location counter
4618 @cindex @code{align} directive
4619 Pad the location counter (in the current subsection) to a particular storage
4620 boundary. The first expression (which must be absolute) is the alignment
4621 required, as described below. If this expression is omitted then a default
4622 value of 0 is used, effectively disabling alignment requirements.
4624 The second expression (also absolute) gives the fill value to be stored in the
4625 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4626 padding bytes are normally zero. However, on most systems, if the section is
4627 marked as containing code and the fill value is omitted, the space is filled
4628 with no-op instructions.
4630 The third expression is also absolute, and is also optional. If it is present,
4631 it is the maximum number of bytes that should be skipped by this alignment
4632 directive. If doing the alignment would require skipping more bytes than the
4633 specified maximum, then the alignment is not done at all. You can omit the
4634 fill value (the second argument) entirely by simply using two commas after the
4635 required alignment; this can be useful if you want the alignment to be filled
4636 with no-op instructions when appropriate.
4638 The way the required alignment is specified varies from system to system.
4639 For the arc, hppa, i386 using ELF, iq2000, m68k, or1k,
4640 s390, sparc, tic4x and xtensa, the first expression is the
4641 alignment request in bytes. For example @samp{.align 8} advances
4642 the location counter until it is a multiple of 8. If the location counter
4643 is already a multiple of 8, no change is needed. For the tic54x, the
4644 first expression is the alignment request in words.
4646 For other systems, including ppc, i386 using a.out format, arm and
4647 strongarm, it is the
4648 number of low-order zero bits the location counter must have after
4649 advancement. For example @samp{.align 3} advances the location
4650 counter until it is a multiple of 8. If the location counter is already a
4651 multiple of 8, no change is needed.
4653 This inconsistency is due to the different behaviors of the various
4654 native assemblers for these systems which GAS must emulate.
4655 GAS also provides @code{.balign} and @code{.p2align} directives,
4656 described later, which have a consistent behavior across all
4657 architectures (but are specific to GAS).
4660 @section @code{.altmacro}
4661 Enable alternate macro mode, enabling:
4664 @item LOCAL @var{name} [ , @dots{} ]
4665 One additional directive, @code{LOCAL}, is available. It is used to
4666 generate a string replacement for each of the @var{name} arguments, and
4667 replace any instances of @var{name} in each macro expansion. The
4668 replacement string is unique in the assembly, and different for each
4669 separate macro expansion. @code{LOCAL} allows you to write macros that
4670 define symbols, without fear of conflict between separate macro expansions.
4672 @item String delimiters
4673 You can write strings delimited in these other ways besides
4674 @code{"@var{string}"}:
4677 @item '@var{string}'
4678 You can delimit strings with single-quote characters.
4680 @item <@var{string}>
4681 You can delimit strings with matching angle brackets.
4684 @item single-character string escape
4685 To include any single character literally in a string (even if the
4686 character would otherwise have some special meaning), you can prefix the
4687 character with @samp{!} (an exclamation mark). For example, you can
4688 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4690 @item Expression results as strings
4691 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4692 and use the result as a string.
4696 @section @code{.ascii "@var{string}"}@dots{}
4698 @cindex @code{ascii} directive
4699 @cindex string literals
4700 @code{.ascii} expects zero or more string literals (@pxref{Strings})
4701 separated by commas. It assembles each string (with no automatic
4702 trailing zero byte) into consecutive addresses.
4705 @section @code{.asciz "@var{string}"}@dots{}
4707 @cindex @code{asciz} directive
4708 @cindex zero-terminated strings
4709 @cindex null-terminated strings
4710 @code{.asciz} is just like @code{.ascii}, but each string is followed by
4711 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''. Note that
4712 multiple string arguments not separated by commas will be concatenated
4713 together and only one final zero byte will be stored.
4715 @node Attach_to_group
4716 @section @code{.attach_to_group @var{name}}
4717 Attaches the current section to the named group. This is like declaring
4718 the section with the @code{G} attribute, but can be done after the section
4719 has been created. Note if the group section does not exist at the point that
4720 this directive is used then it will be created.
4723 @section @code{.balign[wl] [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
4725 @cindex padding the location counter given number of bytes
4726 @cindex @code{balign} directive
4727 Pad the location counter (in the current subsection) to a particular
4728 storage boundary. The first expression (which must be absolute) is the
4729 alignment request in bytes. For example @samp{.balign 8} advances
4730 the location counter until it is a multiple of 8. If the location counter
4731 is already a multiple of 8, no change is needed. If the expression is omitted
4732 then a default value of 0 is used, effectively disabling alignment requirements.
4734 The second expression (also absolute) gives the fill value to be stored in the
4735 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4736 padding bytes are normally zero. However, on most systems, if the section is
4737 marked as containing code and the fill value is omitted, the space is filled
4738 with no-op instructions.
4740 The third expression is also absolute, and is also optional. If it is present,
4741 it is the maximum number of bytes that should be skipped by this alignment
4742 directive. If doing the alignment would require skipping more bytes than the
4743 specified maximum, then the alignment is not done at all. You can omit the
4744 fill value (the second argument) entirely by simply using two commas after the
4745 required alignment; this can be useful if you want the alignment to be filled
4746 with no-op instructions when appropriate.
4748 @cindex @code{balignw} directive
4749 @cindex @code{balignl} directive
4750 The @code{.balignw} and @code{.balignl} directives are variants of the
4751 @code{.balign} directive. The @code{.balignw} directive treats the fill
4752 pattern as a two byte word value. The @code{.balignl} directives treats the
4753 fill pattern as a four byte longword value. For example, @code{.balignw
4754 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4755 filled in with the value 0x368d (the exact placement of the bytes depends upon
4756 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4760 @section @code{.bss @var{subsection}}
4761 @cindex @code{bss} directive
4763 @code{.bss} tells @command{@value{AS}} to assemble the following statements
4764 onto the end of the bss section.
4766 For ELF based targets an optional @var{subsection} expression (which must
4767 evaluate to a positive integer) can be provided. In this case the statements
4768 are appended to the end of the indicated bss subsection.
4771 @node Bundle directives
4772 @section Bundle directives
4773 @subsection @code{.bundle_align_mode @var{abs-expr}}
4774 @cindex @code{bundle_align_mode} directive
4776 @cindex instruction bundle
4777 @cindex aligned instruction bundle
4778 @code{.bundle_align_mode} enables or disables @dfn{aligned instruction
4779 bundle} mode. In this mode, sequences of adjacent instructions are grouped
4780 into fixed-sized @dfn{bundles}. If the argument is zero, this mode is
4781 disabled (which is the default state). If the argument it not zero, it
4782 gives the size of an instruction bundle as a power of two (as for the
4783 @code{.p2align} directive, @pxref{P2align}).
4785 For some targets, it's an ABI requirement that no instruction may span a
4786 certain aligned boundary. A @dfn{bundle} is simply a sequence of
4787 instructions that starts on an aligned boundary. For example, if
4788 @var{abs-expr} is @code{5} then the bundle size is 32, so each aligned
4789 chunk of 32 bytes is a bundle. When aligned instruction bundle mode is in
4790 effect, no single instruction may span a boundary between bundles. If an
4791 instruction would start too close to the end of a bundle for the length of
4792 that particular instruction to fit within the bundle, then the space at the
4793 end of that bundle is filled with no-op instructions so the instruction
4794 starts in the next bundle. As a corollary, it's an error if any single
4795 instruction's encoding is longer than the bundle size.
4797 @subsection @code{.bundle_lock} and @code{.bundle_unlock}
4798 @cindex @code{bundle_lock} directive
4799 @cindex @code{bundle_unlock} directive
4800 The @code{.bundle_lock} and directive @code{.bundle_unlock} directives
4801 allow explicit control over instruction bundle padding. These directives
4802 are only valid when @code{.bundle_align_mode} has been used to enable
4803 aligned instruction bundle mode. It's an error if they appear when
4804 @code{.bundle_align_mode} has not been used at all, or when the last
4805 directive was @w{@code{.bundle_align_mode 0}}.
4807 @cindex bundle-locked
4808 For some targets, it's an ABI requirement that certain instructions may
4809 appear only as part of specified permissible sequences of multiple
4810 instructions, all within the same bundle. A pair of @code{.bundle_lock}
4811 and @code{.bundle_unlock} directives define a @dfn{bundle-locked}
4812 instruction sequence. For purposes of aligned instruction bundle mode, a
4813 sequence starting with @code{.bundle_lock} and ending with
4814 @code{.bundle_unlock} is treated as a single instruction. That is, the
4815 entire sequence must fit into a single bundle and may not span a bundle
4816 boundary. If necessary, no-op instructions will be inserted before the
4817 first instruction of the sequence so that the whole sequence starts on an
4818 aligned bundle boundary. It's an error if the sequence is longer than the
4821 For convenience when using @code{.bundle_lock} and @code{.bundle_unlock}
4822 inside assembler macros (@pxref{Macro}), bundle-locked sequences may be
4823 nested. That is, a second @code{.bundle_lock} directive before the next
4824 @code{.bundle_unlock} directive has no effect except that it must be
4825 matched by another closing @code{.bundle_unlock} so that there is the
4826 same number of @code{.bundle_lock} and @code{.bundle_unlock} directives.
4829 @section @code{.byte @var{expressions}}
4831 @cindex @code{byte} directive
4832 @cindex integers, one byte
4833 @code{.byte} expects zero or more expressions, separated by commas.
4834 Each expression is assembled into the next byte.
4836 @node CFI directives
4837 @section CFI directives
4838 @subsection @code{.cfi_sections @var{section_list}}
4839 @cindex @code{cfi_sections} directive
4840 @code{.cfi_sections} may be used to specify whether CFI directives
4841 should emit @code{.eh_frame} section and/or @code{.debug_frame} section.
4842 If @var{section_list} is @code{.eh_frame}, @code{.eh_frame} is emitted,
4843 if @var{section_list} is @code{.debug_frame}, @code{.debug_frame} is emitted.
4844 To emit both use @code{.eh_frame, .debug_frame}. The default if this
4845 directive is not used is @code{.cfi_sections .eh_frame}.
4847 On targets that support compact unwinding tables these can be generated
4848 by specifying @code{.eh_frame_entry} instead of @code{.eh_frame}.
4850 Some targets may support an additional name, such as @code{.c6xabi.exidx}
4851 which is used by the @value{TIC6X} target.
4853 The @code{.cfi_sections} directive can be repeated, with the same or different
4854 arguments, provided that CFI generation has not yet started. Once CFI
4855 generation has started however the section list is fixed and any attempts to
4856 redefine it will result in an error.
4858 @subsection @code{.cfi_startproc [simple]}
4859 @cindex @code{cfi_startproc} directive
4860 @code{.cfi_startproc} is used at the beginning of each function that
4861 should have an entry in @code{.eh_frame}. It initializes some internal
4862 data structures. Don't forget to close the function by
4863 @code{.cfi_endproc}.
4865 Unless @code{.cfi_startproc} is used along with parameter @code{simple}
4866 it also emits some architecture dependent initial CFI instructions.
4868 @subsection @code{.cfi_endproc}
4869 @cindex @code{cfi_endproc} directive
4870 @code{.cfi_endproc} is used at the end of a function where it closes its
4871 unwind entry previously opened by
4872 @code{.cfi_startproc}, and emits it to @code{.eh_frame}.
4874 @subsection @code{.cfi_personality @var{encoding} [, @var{exp}]}
4875 @cindex @code{cfi_personality} directive
4876 @code{.cfi_personality} defines personality routine and its encoding.
4877 @var{encoding} must be a constant determining how the personality
4878 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4879 argument is not present, otherwise second argument should be
4880 a constant or a symbol name. When using indirect encodings,
4881 the symbol provided should be the location where personality
4882 can be loaded from, not the personality routine itself.
4883 The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff},
4884 no personality routine.
4886 @subsection @code{.cfi_personality_id @var{id}}
4887 @cindex @code{cfi_personality_id} directive
4888 @code{cfi_personality_id} defines a personality routine by its index as
4889 defined in a compact unwinding format.
4890 Only valid when generating compact EH frames (i.e.
4891 with @code{.cfi_sections eh_frame_entry}.
4893 @subsection @code{.cfi_fde_data [@var{opcode1} [, @dots{}]]}
4894 @cindex @code{cfi_fde_data} directive
4895 @code{cfi_fde_data} is used to describe the compact unwind opcodes to be
4896 used for the current function. These are emitted inline in the
4897 @code{.eh_frame_entry} section if small enough and there is no LSDA, or
4898 in the @code{.gnu.extab} section otherwise.
4899 Only valid when generating compact EH frames (i.e.
4900 with @code{.cfi_sections eh_frame_entry}.
4902 @subsection @code{.cfi_lsda @var{encoding} [, @var{exp}]}
4903 @code{.cfi_lsda} defines LSDA and its encoding.
4904 @var{encoding} must be a constant determining how the LSDA
4905 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), the second
4906 argument is not present, otherwise the second argument should be a constant
4907 or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff},
4908 meaning that no LSDA is present.
4910 @subsection @code{.cfi_inline_lsda} [@var{align}]
4911 @code{.cfi_inline_lsda} marks the start of a LSDA data section and
4912 switches to the corresponding @code{.gnu.extab} section.
4913 Must be preceded by a CFI block containing a @code{.cfi_lsda} directive.
4914 Only valid when generating compact EH frames (i.e.
4915 with @code{.cfi_sections eh_frame_entry}.
4917 The table header and unwinding opcodes will be generated at this point,
4918 so that they are immediately followed by the LSDA data. The symbol
4919 referenced by the @code{.cfi_lsda} directive should still be defined
4920 in case a fallback FDE based encoding is used. The LSDA data is terminated
4921 by a section directive.
4923 The optional @var{align} argument specifies the alignment required.
4924 The alignment is specified as a power of two, as with the
4925 @code{.p2align} directive.
4927 @subsection @code{.cfi_def_cfa @var{register}, @var{offset}}
4928 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4929 address from @var{register} and add @var{offset} to it}.
4931 @subsection @code{.cfi_def_cfa_register @var{register}}
4932 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4933 now on @var{register} will be used instead of the old one. Offset
4936 @subsection @code{.cfi_def_cfa_offset @var{offset}}
4937 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4938 remains the same, but @var{offset} is new. Note that it is the
4939 absolute offset that will be added to a defined register to compute
4942 @subsection @code{.cfi_adjust_cfa_offset @var{offset}}
4943 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4944 value that is added/subtracted from the previous offset.
4946 @subsection @code{.cfi_offset @var{register}, @var{offset}}
4947 Previous value of @var{register} is saved at offset @var{offset} from
4950 @subsection @code{.cfi_val_offset @var{register}, @var{offset}}
4951 Previous value of @var{register} is CFA + @var{offset}.
4953 @subsection @code{.cfi_rel_offset @var{register}, @var{offset}}
4954 Previous value of @var{register} is saved at offset @var{offset} from
4955 the current CFA register. This is transformed to @code{.cfi_offset}
4956 using the known displacement of the CFA register from the CFA.
4957 This is often easier to use, because the number will match the
4958 code it's annotating.
4960 @subsection @code{.cfi_register @var{register1}, @var{register2}}
4961 Previous value of @var{register1} is saved in register @var{register2}.
4963 @subsection @code{.cfi_restore @var{register}}
4964 @code{.cfi_restore} says that the rule for @var{register} is now the
4965 same as it was at the beginning of the function, after all initial
4966 instruction added by @code{.cfi_startproc} were executed.
4968 @subsection @code{.cfi_undefined @var{register}}
4969 From now on the previous value of @var{register} can't be restored anymore.
4971 @subsection @code{.cfi_same_value @var{register}}
4972 Current value of @var{register} is the same like in the previous frame,
4973 i.e. no restoration needed.
4975 @subsection @code{.cfi_remember_state} and @code{.cfi_restore_state}
4976 @code{.cfi_remember_state} pushes the set of rules for every register onto an
4977 implicit stack, while @code{.cfi_restore_state} pops them off the stack and
4978 places them in the current row. This is useful for situations where you have
4979 multiple @code{.cfi_*} directives that need to be undone due to the control
4980 flow of the program. For example, we could have something like this (assuming
4981 the CFA is the value of @code{rbp}):
4991 .cfi_def_cfa %rsp, 8
4994 /* Do something else */
4997 Here, we want the @code{.cfi} directives to affect only the rows corresponding
4998 to the instructions before @code{label}. This means we'd have to add multiple
4999 @code{.cfi} directives after @code{label} to recreate the original save
5000 locations of the registers, as well as setting the CFA back to the value of
5001 @code{rbp}. This would be clumsy, and result in a larger binary size. Instead,
5013 .cfi_def_cfa %rsp, 8
5017 /* Do something else */
5020 That way, the rules for the instructions after @code{label} will be the same
5021 as before the first @code{.cfi_restore} without having to use multiple
5022 @code{.cfi} directives.
5024 @subsection @code{.cfi_return_column @var{register}}
5025 Change return column @var{register}, i.e. the return address is either
5026 directly in @var{register} or can be accessed by rules for @var{register}.
5028 @subsection @code{.cfi_signal_frame}
5029 Mark current function as signal trampoline.
5031 @subsection @code{.cfi_window_save}
5032 SPARC register window has been saved.
5034 @subsection @code{.cfi_escape} @var{expression}[, @dots{}]
5035 Allows the user to add arbitrary bytes to the unwind info. One
5036 might use this to add OS-specific CFI opcodes, or generic CFI
5037 opcodes that GAS does not yet support.
5039 @subsection @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}}
5040 The current value of @var{register} is @var{label}. The value of @var{label}
5041 will be encoded in the output file according to @var{encoding}; see the
5042 description of @code{.cfi_personality} for details on this encoding.
5044 The usefulness of equating a register to a fixed label is probably
5045 limited to the return address register. Here, it can be useful to
5046 mark a code segment that has only one return address which is reached
5047 by a direct branch and no copy of the return address exists in memory
5048 or another register.
5051 @section @code{.comm @var{symbol} , @var{length} }
5053 @cindex @code{comm} directive
5054 @cindex symbol, common
5055 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
5056 common symbol in one object file may be merged with a defined or common symbol
5057 of the same name in another object file. If @code{@value{LD}} does not see a
5058 definition for the symbol--just one or more common symbols--then it will
5059 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
5060 absolute expression. If @code{@value{LD}} sees multiple common symbols with
5061 the same name, and they do not all have the same size, it will allocate space
5062 using the largest size.
5065 When using ELF or (as a GNU extension) PE, the @code{.comm} directive takes
5066 an optional third argument. This is the desired alignment of the symbol,
5067 specified for ELF as a byte boundary (for example, an alignment of 16 means
5068 that the least significant 4 bits of the address should be zero), and for PE
5069 as a power of two (for example, an alignment of 5 means aligned to a 32-byte
5070 boundary). The alignment must be an absolute expression, and it must be a
5071 power of two. If @code{@value{LD}} allocates uninitialized memory for the
5072 common symbol, it will use the alignment when placing the symbol. If no
5073 alignment is specified, @command{@value{AS}} will set the alignment to the
5074 largest power of two less than or equal to the size of the symbol, up to a
5075 maximum of 16 on ELF, or the default section alignment of 4 on PE@footnote{This
5076 is not the same as the executable image file alignment controlled by @code{@value{LD}}'s
5077 @samp{--section-alignment} option; image file sections in PE are aligned to
5078 multiples of 4096, which is far too large an alignment for ordinary variables.
5079 It is rather the default alignment for (non-debug) sections within object
5080 (@samp{*.o}) files, which are less strictly aligned.}.
5084 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
5085 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
5089 @section @code{.data @var{subsection}}
5090 @cindex @code{data} directive
5092 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
5093 end of the data subsection numbered @var{subsection} (which is an
5094 absolute expression). If @var{subsection} is omitted, it defaults
5098 @section @code{.dc[@var{size}] @var{expressions}}
5099 @cindex @code{dc} directive
5101 The @code{.dc} directive expects zero or more @var{expressions} separated by
5102 commas. These expressions are evaluated and their values inserted into the
5103 current section. The size of the emitted value depends upon the suffix to the
5104 @code{.dc} directive:
5108 Emits N-bit values, where N is the size of an address on the target system.
5112 Emits double precision floating-point values.
5114 Emits 32-bit values.
5116 Emits single precision floating-point values.
5118 Emits 16-bit values.
5119 Note - this is true even on targets where the @code{.word} directive would emit
5122 Emits long double precision floating-point values.
5125 If no suffix is used then @samp{.w} is assumed.
5127 The byte ordering is target dependent, as is the size and format of floating
5131 @section @code{.dcb[@var{size}] @var{number} [,@var{fill}]}
5132 @cindex @code{dcb} directive
5133 This directive emits @var{number} copies of @var{fill}, each of @var{size}
5134 bytes. Both @var{number} and @var{fill} are absolute expressions. If the
5135 comma and @var{fill} are omitted, @var{fill} is assumed to be zero. The
5136 @var{size} suffix, if present, must be one of:
5140 Emits single byte values.
5142 Emits double-precision floating point values.
5144 Emits 4-byte values.
5146 Emits single-precision floating point values.
5148 Emits 2-byte values.
5150 Emits long double-precision floating point values.
5153 If the @var{size} suffix is omitted then @samp{.w} is assumed.
5155 The byte ordering is target dependent, as is the size and format of floating
5159 @section @code{.ds[@var{size}] @var{number} [,@var{fill}]}
5160 @cindex @code{ds} directive
5161 This directive emits @var{number} copies of @var{fill}, each of @var{size}
5162 bytes. Both @var{number} and @var{fill} are absolute expressions. If the
5163 comma and @var{fill} are omitted, @var{fill} is assumed to be zero. The
5164 @var{size} suffix, if present, must be one of:
5168 Emits single byte values.
5170 Emits 8-byte values.
5172 Emits 4-byte values.
5174 Emits values with size matching packed-decimal floating-point ones.
5176 Emits 4-byte values.
5178 Emits 2-byte values.
5180 Emits values with size matching long double precision floating-point ones.
5183 Note - unlike the @code{.dcb} directive the @samp{.d}, @samp{.s} and @samp{.x}
5184 suffixes do not indicate that floating-point values are to be inserted.
5186 If the @var{size} suffix is omitted then @samp{.w} is assumed.
5188 The byte ordering is target dependent.
5193 @section @code{.def @var{name}}
5195 @cindex @code{def} directive
5196 @cindex COFF symbols, debugging
5197 @cindex debugging COFF symbols
5198 Begin defining debugging information for a symbol @var{name}; the
5199 definition extends until the @code{.endef} directive is encountered.
5204 @section @code{.desc @var{symbol}, @var{abs-expression}}
5206 @cindex @code{desc} directive
5207 @cindex COFF symbol descriptor
5208 @cindex symbol descriptor, COFF
5209 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
5210 to the low 16 bits of an absolute expression.
5213 The @samp{.desc} directive is not available when @command{@value{AS}} is
5214 configured for COFF output; it is only for @code{a.out} or @code{b.out}
5215 object format. For the sake of compatibility, @command{@value{AS}} accepts
5216 it, but produces no output, when configured for COFF.
5222 @section @code{.dim}
5224 @cindex @code{dim} directive
5225 @cindex COFF auxiliary symbol information
5226 @cindex auxiliary symbol information, COFF
5227 This directive is generated by compilers to include auxiliary debugging
5228 information in the symbol table. It is only permitted inside
5229 @code{.def}/@code{.endef} pairs.
5233 @section @code{.double @var{flonums}}
5235 @cindex @code{double} directive
5236 @cindex floating point numbers (double)
5237 @code{.double} expects zero or more flonums, separated by commas. It
5238 assembles floating point numbers.
5240 The exact kind of floating point numbers emitted depends on how
5241 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5245 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
5246 in @sc{ieee} format.
5251 @section @code{.eject}
5253 @cindex @code{eject} directive
5254 @cindex new page, in listings
5255 @cindex page, in listings
5256 @cindex listing control: new page
5257 Force a page break at this point, when generating assembly listings.
5260 @section @code{.else}
5262 @cindex @code{else} directive
5263 @code{.else} is part of the @command{@value{AS}} support for conditional
5264 assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section
5265 of code to be assembled if the condition for the preceding @code{.if}
5269 @section @code{.elseif}
5271 @cindex @code{elseif} directive
5272 @code{.elseif} is part of the @command{@value{AS}} support for conditional
5273 assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new
5274 @code{.if} block that would otherwise fill the entire @code{.else} section.
5277 @section @code{.end}
5279 @cindex @code{end} directive
5280 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
5281 process anything in the file past the @code{.end} directive.
5285 @section @code{.endef}
5287 @cindex @code{endef} directive
5288 This directive flags the end of a symbol definition begun with
5293 @section @code{.endfunc}
5294 @cindex @code{endfunc} directive
5295 @code{.endfunc} marks the end of a function specified with @code{.func}.
5298 @section @code{.endif}
5300 @cindex @code{endif} directive
5301 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
5302 it marks the end of a block of code that is only assembled
5303 conditionally. @xref{If,,@code{.if}}.
5306 @section @code{.equ @var{symbol}, @var{expression}}
5308 @cindex @code{equ} directive
5309 @cindex assigning values to symbols
5310 @cindex symbols, assigning values to
5311 This directive sets the value of @var{symbol} to @var{expression}.
5312 It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}.
5315 The syntax for @code{equ} on the HPPA is
5316 @samp{@var{symbol} .equ @var{expression}}.
5320 The syntax for @code{equ} on the Z80 is
5321 @samp{@var{symbol} equ @var{expression}}.
5322 On the Z80 it is an error if @var{symbol} is already defined,
5323 but the symbol is not protected from later redefinition.
5324 Compare @ref{Equiv}.
5328 @section @code{.equiv @var{symbol}, @var{expression}}
5329 @cindex @code{equiv} directive
5330 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
5331 the assembler will signal an error if @var{symbol} is already defined. Note a
5332 symbol which has been referenced but not actually defined is considered to be
5335 Except for the contents of the error message, this is roughly equivalent to
5342 plus it protects the symbol from later redefinition.
5345 @section @code{.eqv @var{symbol}, @var{expression}}
5346 @cindex @code{eqv} directive
5347 The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to
5348 evaluate the expression or any part of it immediately. Instead each time
5349 the resulting symbol is used in an expression, a snapshot of its current
5353 @section @code{.err}
5354 @cindex @code{err} directive
5355 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
5356 message and, unless the @option{-Z} option was used, it will not generate an
5357 object file. This can be used to signal an error in conditionally compiled code.
5360 @section @code{.error "@var{string}"}
5361 @cindex error directive
5363 Similarly to @code{.err}, this directive emits an error, but you can specify a
5364 string that will be emitted as the error message. If you don't specify the
5365 message, it defaults to @code{".error directive invoked in source file"}.
5366 @xref{Errors, ,Error and Warning Messages}.
5369 .error "This code has not been assembled and tested."
5373 @section @code{.exitm}
5374 Exit early from the current macro definition. @xref{Macro}.
5377 @section @code{.extern}
5379 @cindex @code{extern} directive
5380 @code{.extern} is accepted in the source program---for compatibility
5381 with other assemblers---but it is ignored. @command{@value{AS}} treats
5382 all undefined symbols as external.
5385 @section @code{.fail @var{expression}}
5387 @cindex @code{fail} directive
5388 Generates an error or a warning. If the value of the @var{expression} is 500
5389 or more, @command{@value{AS}} will print a warning message. If the value is less
5390 than 500, @command{@value{AS}} will print an error message. The message will
5391 include the value of @var{expression}. This can occasionally be useful inside
5392 complex nested macros or conditional assembly.
5395 @section @code{.file}
5396 @cindex @code{file} directive
5398 @ifclear no-file-dir
5399 There are two different versions of the @code{.file} directive. Targets
5400 that support DWARF2 line number information use the DWARF2 version of
5401 @code{.file}. Other targets use the default version.
5403 @subheading Default Version
5405 @cindex logical file name
5406 @cindex file name, logical
5407 This version of the @code{.file} directive tells @command{@value{AS}} that we
5408 are about to start a new logical file. The syntax is:
5414 @var{string} is the new file name. In general, the filename is
5415 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
5416 to specify an empty file name, you must give the quotes--@code{""}. This
5417 statement may go away in future: it is only recognized to be compatible with
5418 old @command{@value{AS}} programs.
5420 @subheading DWARF2 Version
5423 When emitting DWARF2 line number information, @code{.file} assigns filenames
5424 to the @code{.debug_line} file name table. The syntax is:
5427 .file @var{fileno} @var{filename}
5430 The @var{fileno} operand should be a unique positive integer to use as the
5431 index of the entry in the table. The @var{filename} operand is a C string
5432 literal enclosed in double quotes. The @var{filename} can include directory
5433 elements. If it does, then the directory will be added to the directory table
5434 and the basename will be added to the file table.
5436 The detail of filename indices is exposed to the user because the filename
5437 table is shared with the @code{.debug_info} section of the DWARF2 debugging
5438 information, and thus the user must know the exact indices that table
5441 If DWARF5 support has been enabled via the @option{-gdwarf-5} option then
5442 an extended version of @code{.file} is also allowed:
5445 .file @var{fileno} [@var{dirname}] @var{filename} [md5 @var{value}]
5448 With this version a separate directory name is allowed, although if this is
5449 used then @var{filename} should not contain any directory component, except
5450 for @var{fileno} equal to 0: in this case, @var{dirname} is expected to be
5451 the current directory and @var{filename} the currently processed file, and
5452 the latter need not be located in the former. In addtion an MD5 hash value
5453 of the contents of @var{filename} can be provided. This will be stored in
5454 the the file table as well, and can be used by tools reading the debug
5455 information to verify that the contents of the source file match the
5456 contents of the compiled file.
5459 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
5461 @cindex @code{fill} directive
5462 @cindex writing patterns in memory
5463 @cindex patterns, writing in memory
5464 @var{repeat}, @var{size} and @var{value} are absolute expressions.
5465 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
5466 may be zero or more. @var{Size} may be zero or more, but if it is
5467 more than 8, then it is deemed to have the value 8, compatible with
5468 other people's assemblers. The contents of each @var{repeat} bytes
5469 is taken from an 8-byte number. The highest order 4 bytes are
5470 zero. The lowest order 4 bytes are @var{value} rendered in the
5471 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
5472 Each @var{size} bytes in a repetition is taken from the lowest order
5473 @var{size} bytes of this number. Again, this bizarre behavior is
5474 compatible with other people's assemblers.
5476 @var{size} and @var{value} are optional.
5477 If the second comma and @var{value} are absent, @var{value} is
5478 assumed zero. If the first comma and following tokens are absent,
5479 @var{size} is assumed to be 1.
5482 @section @code{.float @var{flonums}}
5484 @cindex floating point numbers (single)
5485 @cindex @code{float} directive
5486 This directive assembles zero or more flonums, separated by commas. It
5487 has the same effect as @code{.single}.
5489 The exact kind of floating point numbers emitted depends on how
5490 @command{@value{AS}} is configured.
5491 @xref{Machine Dependencies}.
5495 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
5496 in @sc{ieee} format.
5501 @section @code{.func @var{name}[,@var{label}]}
5502 @cindex @code{func} directive
5503 @code{.func} emits debugging information to denote function @var{name}, and
5504 is ignored unless the file is assembled with debugging enabled.
5505 Only @samp{--gstabs[+]} is currently supported.
5506 @var{label} is the entry point of the function and if omitted @var{name}
5507 prepended with the @samp{leading char} is used.
5508 @samp{leading char} is usually @code{_} or nothing, depending on the target.
5509 All functions are currently defined to have @code{void} return type.
5510 The function must be terminated with @code{.endfunc}.
5513 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
5515 @cindex @code{global} directive
5516 @cindex symbol, making visible to linker
5517 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
5518 @var{symbol} in your partial program, its value is made available to
5519 other partial programs that are linked with it. Otherwise,
5520 @var{symbol} takes its attributes from a symbol of the same name
5521 from another file linked into the same program.
5523 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
5524 compatibility with other assemblers.
5527 On the HPPA, @code{.global} is not always enough to make it accessible to other
5528 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
5529 @xref{HPPA Directives, ,HPPA Assembler Directives}.
5534 @section @code{.gnu_attribute @var{tag},@var{value}}
5535 Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
5538 @section @code{.hidden @var{names}}
5540 @cindex @code{hidden} directive
5542 This is one of the ELF visibility directives. The other two are
5543 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
5544 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5546 This directive overrides the named symbols default visibility (which is set by
5547 their binding: local, global or weak). The directive sets the visibility to
5548 @code{hidden} which means that the symbols are not visible to other components.
5549 Such symbols are always considered to be @code{protected} as well.
5553 @section @code{.hword @var{expressions}}
5555 @cindex @code{hword} directive
5556 @cindex integers, 16-bit
5557 @cindex numbers, 16-bit
5558 @cindex sixteen bit integers
5559 This expects zero or more @var{expressions}, and emits
5560 a 16 bit number for each.
5563 This directive is a synonym for @samp{.short}; depending on the target
5564 architecture, it may also be a synonym for @samp{.word}.
5568 This directive is a synonym for @samp{.short}.
5571 This directive is a synonym for both @samp{.short} and @samp{.word}.
5576 @section @code{.ident}
5578 @cindex @code{ident} directive
5580 This directive is used by some assemblers to place tags in object files. The
5581 behavior of this directive varies depending on the target. When using the
5582 a.out object file format, @command{@value{AS}} simply accepts the directive for
5583 source-file compatibility with existing assemblers, but does not emit anything
5584 for it. When using COFF, comments are emitted to the @code{.comment} or
5585 @code{.rdata} section, depending on the target. When using ELF, comments are
5586 emitted to the @code{.comment} section.
5589 @section @code{.if @var{absolute expression}}
5591 @cindex conditional assembly
5592 @cindex @code{if} directive
5593 @code{.if} marks the beginning of a section of code which is only
5594 considered part of the source program being assembled if the argument
5595 (which must be an @var{absolute expression}) is non-zero. The end of
5596 the conditional section of code must be marked by @code{.endif}
5597 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
5598 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
5599 If you have several conditions to check, @code{.elseif} may be used to avoid
5600 nesting blocks if/else within each subsequent @code{.else} block.
5602 The following variants of @code{.if} are also supported:
5604 @cindex @code{ifdef} directive
5605 @item .ifdef @var{symbol}
5606 Assembles the following section of code if the specified @var{symbol}
5607 has been defined. Note a symbol which has been referenced but not yet defined
5608 is considered to be undefined.
5610 @cindex @code{ifb} directive
5611 @item .ifb @var{text}
5612 Assembles the following section of code if the operand is blank (empty).
5614 @cindex @code{ifc} directive
5615 @item .ifc @var{string1},@var{string2}
5616 Assembles the following section of code if the two strings are the same. The
5617 strings may be optionally quoted with single quotes. If they are not quoted,
5618 the first string stops at the first comma, and the second string stops at the
5619 end of the line. Strings which contain whitespace should be quoted. The
5620 string comparison is case sensitive.
5622 @cindex @code{ifeq} directive
5623 @item .ifeq @var{absolute expression}
5624 Assembles the following section of code if the argument is zero.
5626 @cindex @code{ifeqs} directive
5627 @item .ifeqs @var{string1},@var{string2}
5628 Another form of @code{.ifc}. The strings must be quoted using double quotes.
5630 @cindex @code{ifge} directive
5631 @item .ifge @var{absolute expression}
5632 Assembles the following section of code if the argument is greater than or
5635 @cindex @code{ifgt} directive
5636 @item .ifgt @var{absolute expression}
5637 Assembles the following section of code if the argument is greater than zero.
5639 @cindex @code{ifle} directive
5640 @item .ifle @var{absolute expression}
5641 Assembles the following section of code if the argument is less than or equal
5644 @cindex @code{iflt} directive
5645 @item .iflt @var{absolute expression}
5646 Assembles the following section of code if the argument is less than zero.
5648 @cindex @code{ifnb} directive
5649 @item .ifnb @var{text}
5650 Like @code{.ifb}, but the sense of the test is reversed: this assembles the
5651 following section of code if the operand is non-blank (non-empty).
5653 @cindex @code{ifnc} directive
5654 @item .ifnc @var{string1},@var{string2}.
5655 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
5656 following section of code if the two strings are not the same.
5658 @cindex @code{ifndef} directive
5659 @cindex @code{ifnotdef} directive
5660 @item .ifndef @var{symbol}
5661 @itemx .ifnotdef @var{symbol}
5662 Assembles the following section of code if the specified @var{symbol}
5663 has not been defined. Both spelling variants are equivalent. Note a symbol
5664 which has been referenced but not yet defined is considered to be undefined.
5666 @cindex @code{ifne} directive
5667 @item .ifne @var{absolute expression}
5668 Assembles the following section of code if the argument is not equal to zero
5669 (in other words, this is equivalent to @code{.if}).
5671 @cindex @code{ifnes} directive
5672 @item .ifnes @var{string1},@var{string2}
5673 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
5674 following section of code if the two strings are not the same.
5678 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
5680 @cindex @code{incbin} directive
5681 @cindex binary files, including
5682 The @code{incbin} directive includes @var{file} verbatim at the current
5683 location. You can control the search paths used with the @samp{-I} command-line
5684 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5687 The @var{skip} argument skips a number of bytes from the start of the
5688 @var{file}. The @var{count} argument indicates the maximum number of bytes to
5689 read. Note that the data is not aligned in any way, so it is the user's
5690 responsibility to make sure that proper alignment is provided both before and
5691 after the @code{incbin} directive.
5694 @section @code{.include "@var{file}"}
5696 @cindex @code{include} directive
5697 @cindex supporting files, including
5698 @cindex files, including
5699 This directive provides a way to include supporting files at specified
5700 points in your source program. The code from @var{file} is assembled as
5701 if it followed the point of the @code{.include}; when the end of the
5702 included file is reached, assembly of the original file continues. You
5703 can control the search paths used with the @samp{-I} command-line option
5704 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5708 @section @code{.int @var{expressions}}
5710 @cindex @code{int} directive
5711 @cindex integers, 32-bit
5712 Expect zero or more @var{expressions}, of any section, separated by commas.
5713 For each expression, emit a number that, at run time, is the value of that
5714 expression. The byte order and bit size of the number depends on what kind
5715 of target the assembly is for.
5719 On most forms of the H8/300, @code{.int} emits 16-bit
5720 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
5727 @section @code{.internal @var{names}}
5729 @cindex @code{internal} directive
5731 This is one of the ELF visibility directives. The other two are
5732 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
5733 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5735 This directive overrides the named symbols default visibility (which is set by
5736 their binding: local, global or weak). The directive sets the visibility to
5737 @code{internal} which means that the symbols are considered to be @code{hidden}
5738 (i.e., not visible to other components), and that some extra, processor specific
5739 processing must also be performed upon the symbols as well.
5743 @section @code{.irp @var{symbol},@var{values}}@dots{}
5745 @cindex @code{irp} directive
5746 Evaluate a sequence of statements assigning different values to @var{symbol}.
5747 The sequence of statements starts at the @code{.irp} directive, and is
5748 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
5749 set to @var{value}, and the sequence of statements is assembled. If no
5750 @var{value} is listed, the sequence of statements is assembled once, with
5751 @var{symbol} set to the null string. To refer to @var{symbol} within the
5752 sequence of statements, use @var{\symbol}.
5754 For example, assembling
5762 is equivalent to assembling
5770 For some caveats with the spelling of @var{symbol}, see also @ref{Macro}.
5773 @section @code{.irpc @var{symbol},@var{values}}@dots{}
5775 @cindex @code{irpc} directive
5776 Evaluate a sequence of statements assigning different values to @var{symbol}.
5777 The sequence of statements starts at the @code{.irpc} directive, and is
5778 terminated by an @code{.endr} directive. For each character in @var{value},
5779 @var{symbol} is set to the character, and the sequence of statements is
5780 assembled. If no @var{value} is listed, the sequence of statements is
5781 assembled once, with @var{symbol} set to the null string. To refer to
5782 @var{symbol} within the sequence of statements, use @var{\symbol}.
5784 For example, assembling
5792 is equivalent to assembling
5800 For some caveats with the spelling of @var{symbol}, see also the discussion
5804 @section @code{.lcomm @var{symbol} , @var{length}}
5806 @cindex @code{lcomm} directive
5807 @cindex local common symbols
5808 @cindex symbols, local common
5809 Reserve @var{length} (an absolute expression) bytes for a local common
5810 denoted by @var{symbol}. The section and value of @var{symbol} are
5811 those of the new local common. The addresses are allocated in the bss
5812 section, so that at run-time the bytes start off zeroed. @var{Symbol}
5813 is not declared global (@pxref{Global,,@code{.global}}), so is normally
5814 not visible to @code{@value{LD}}.
5817 Some targets permit a third argument to be used with @code{.lcomm}. This
5818 argument specifies the desired alignment of the symbol in the bss section.
5822 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
5823 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
5827 @section @code{.lflags}
5829 @cindex @code{lflags} directive (ignored)
5830 @command{@value{AS}} accepts this directive, for compatibility with other
5831 assemblers, but ignores it.
5833 @ifclear no-line-dir
5835 @section @code{.line @var{line-number}}
5837 @cindex @code{line} directive
5838 @cindex logical line number
5840 Change the logical line number. @var{line-number} must be an absolute
5841 expression. The next line has that logical line number. Therefore any other
5842 statements on the current line (after a statement separator character) are
5843 reported as on logical line number @var{line-number} @minus{} 1. One day
5844 @command{@value{AS}} will no longer support this directive: it is recognized only
5845 for compatibility with existing assembler programs.
5848 Even though this is a directive associated with the @code{a.out} or
5849 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
5850 when producing COFF output, and treats @samp{.line} as though it
5851 were the COFF @samp{.ln} @emph{if} it is found outside a
5852 @code{.def}/@code{.endef} pair.
5854 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
5855 used by compilers to generate auxiliary symbol information for
5860 @section @code{.linkonce [@var{type}]}
5862 @cindex @code{linkonce} directive
5863 @cindex common sections
5864 Mark the current section so that the linker only includes a single copy of it.
5865 This may be used to include the same section in several different object files,
5866 but ensure that the linker will only include it once in the final output file.
5867 The @code{.linkonce} pseudo-op must be used for each instance of the section.
5868 Duplicate sections are detected based on the section name, so it should be
5871 This directive is only supported by a few object file formats; as of this
5872 writing, the only object file format which supports it is the Portable
5873 Executable format used on Windows NT.
5875 The @var{type} argument is optional. If specified, it must be one of the
5876 following strings. For example:
5880 Not all types may be supported on all object file formats.
5884 Silently discard duplicate sections. This is the default.
5887 Warn if there are duplicate sections, but still keep only one copy.
5890 Warn if any of the duplicates have different sizes.
5893 Warn if any of the duplicates do not have exactly the same contents.
5897 @section @code{.list}
5899 @cindex @code{list} directive
5900 @cindex listing control, turning on
5901 Control (in conjunction with the @code{.nolist} directive) whether or
5902 not assembly listings are generated. These two directives maintain an
5903 internal counter (which is zero initially). @code{.list} increments the
5904 counter, and @code{.nolist} decrements it. Assembly listings are
5905 generated whenever the counter is greater than zero.
5907 By default, listings are disabled. When you enable them (with the
5908 @samp{-a} command-line option; @pxref{Invoking,,Command-Line Options}),
5909 the initial value of the listing counter is one.
5912 @section @code{.ln @var{line-number}}
5914 @cindex @code{ln} directive
5915 @ifclear no-line-dir
5916 @samp{.ln} is a synonym for @samp{.line}.
5919 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
5920 must be an absolute expression. The next line has that logical
5921 line number, so any other statements on the current line (after a
5922 statement separator character @code{;}) are reported as on logical
5923 line number @var{line-number} @minus{} 1.
5927 @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]}
5928 @cindex @code{loc} directive
5929 When emitting DWARF2 line number information,
5930 the @code{.loc} directive will add a row to the @code{.debug_line} line
5931 number matrix corresponding to the immediately following assembly
5932 instruction. The @var{fileno}, @var{lineno}, and optional @var{column}
5933 arguments will be applied to the @code{.debug_line} state machine before
5934 the row is added. It is an error for the input assembly file to generate
5935 a non-empty @code{.debug_line} and also use @code{loc} directives.
5937 The @var{options} are a sequence of the following tokens in any order:
5941 This option will set the @code{basic_block} register in the
5942 @code{.debug_line} state machine to @code{true}.
5945 This option will set the @code{prologue_end} register in the
5946 @code{.debug_line} state machine to @code{true}.
5948 @item epilogue_begin
5949 This option will set the @code{epilogue_begin} register in the
5950 @code{.debug_line} state machine to @code{true}.
5952 @item is_stmt @var{value}
5953 This option will set the @code{is_stmt} register in the
5954 @code{.debug_line} state machine to @code{value}, which must be
5957 @item isa @var{value}
5958 This directive will set the @code{isa} register in the @code{.debug_line}
5959 state machine to @var{value}, which must be an unsigned integer.
5961 @item discriminator @var{value}
5962 This directive will set the @code{discriminator} register in the @code{.debug_line}
5963 state machine to @var{value}, which must be an unsigned integer.
5965 @item view @var{value}
5966 This option causes a row to be added to @code{.debug_line} in reference to the
5967 current address (which might not be the same as that of the following assembly
5968 instruction), and to associate @var{value} with the @code{view} register in the
5969 @code{.debug_line} state machine. If @var{value} is a label, both the
5970 @code{view} register and the label are set to the number of prior @code{.loc}
5971 directives at the same program location. If @var{value} is the literal
5972 @code{0}, the @code{view} register is set to zero, and the assembler asserts
5973 that there aren't any prior @code{.loc} directives at the same program
5974 location. If @var{value} is the literal @code{-0}, the assembler arrange for
5975 the @code{view} register to be reset in this row, even if there are prior
5976 @code{.loc} directives at the same program location.
5980 @node Loc_mark_labels
5981 @section @code{.loc_mark_labels @var{enable}}
5982 @cindex @code{loc_mark_labels} directive
5983 When emitting DWARF2 line number information,
5984 the @code{.loc_mark_labels} directive makes the assembler emit an entry
5985 to the @code{.debug_line} line number matrix with the @code{basic_block}
5986 register in the state machine set whenever a code label is seen.
5987 The @var{enable} argument should be either 1 or 0, to enable or disable
5988 this function respectively.
5992 @section @code{.local @var{names}}
5994 @cindex @code{local} directive
5995 This directive, which is available for ELF targets, marks each symbol in
5996 the comma-separated list of @code{names} as a local symbol so that it
5997 will not be externally visible. If the symbols do not already exist,
5998 they will be created.
6000 For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not
6001 accept an alignment argument, which is the case for most ELF targets,
6002 the @code{.local} directive can be used in combination with @code{.comm}
6003 (@pxref{Comm}) to define aligned local common data.
6007 @section @code{.long @var{expressions}}
6009 @cindex @code{long} directive
6010 @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}.
6013 @c no one seems to know what this is for or whether this description is
6014 @c what it really ought to do
6016 @section @code{.lsym @var{symbol}, @var{expression}}
6018 @cindex @code{lsym} directive
6019 @cindex symbol, not referenced in assembly
6020 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
6021 the hash table, ensuring it cannot be referenced by name during the
6022 rest of the assembly. This sets the attributes of the symbol to be
6023 the same as the expression value:
6025 @var{other} = @var{descriptor} = 0
6026 @var{type} = @r{(section of @var{expression})}
6027 @var{value} = @var{expression}
6030 The new symbol is not flagged as external.
6034 @section @code{.macro}
6037 The commands @code{.macro} and @code{.endm} allow you to define macros that
6038 generate assembly output. For example, this definition specifies a macro
6039 @code{sum} that puts a sequence of numbers into memory:
6042 .macro sum from=0, to=5
6051 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
6063 @item .macro @var{macname}
6064 @itemx .macro @var{macname} @var{macargs} @dots{}
6065 @cindex @code{macro} directive
6066 Begin the definition of a macro called @var{macname}. If your macro
6067 definition requires arguments, specify their names after the macro name,
6068 separated by commas or spaces. You can qualify the macro argument to
6069 indicate whether all invocations must specify a non-blank value (through
6070 @samp{:@code{req}}), or whether it takes all of the remaining arguments
6071 (through @samp{:@code{vararg}}). You can supply a default value for any
6072 macro argument by following the name with @samp{=@var{deflt}}. You
6073 cannot define two macros with the same @var{macname} unless it has been
6074 subject to the @code{.purgem} directive (@pxref{Purgem}) between the two
6075 definitions. For example, these are all valid @code{.macro} statements:
6079 Begin the definition of a macro called @code{comm}, which takes no
6082 @item .macro plus1 p, p1
6083 @itemx .macro plus1 p p1
6084 Either statement begins the definition of a macro called @code{plus1},
6085 which takes two arguments; within the macro definition, write
6086 @samp{\p} or @samp{\p1} to evaluate the arguments.
6088 @item .macro reserve_str p1=0 p2
6089 Begin the definition of a macro called @code{reserve_str}, with two
6090 arguments. The first argument has a default value, but not the second.
6091 After the definition is complete, you can call the macro either as
6092 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
6093 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
6094 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
6095 @samp{0}, and @samp{\p2} evaluating to @var{b}).
6097 @item .macro m p1:req, p2=0, p3:vararg
6098 Begin the definition of a macro called @code{m}, with at least three
6099 arguments. The first argument must always have a value specified, but
6100 not the second, which instead has a default value. The third formal
6101 will get assigned all remaining arguments specified at invocation time.
6103 When you call a macro, you can specify the argument values either by
6104 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
6105 @samp{sum to=17, from=9}.
6109 Note that since each of the @var{macargs} can be an identifier exactly
6110 as any other one permitted by the target architecture, there may be
6111 occasional problems if the target hand-crafts special meanings to certain
6112 characters when they occur in a special position. For example, if the colon
6113 (@code{:}) is generally permitted to be part of a symbol name, but the
6114 architecture specific code special-cases it when occurring as the final
6115 character of a symbol (to denote a label), then the macro parameter
6116 replacement code will have no way of knowing that and consider the whole
6117 construct (including the colon) an identifier, and check only this
6118 identifier for being the subject to parameter substitution. So for example
6119 this macro definition:
6127 might not work as expected. Invoking @samp{label foo} might not create a label
6128 called @samp{foo} but instead just insert the text @samp{\l:} into the
6129 assembler source, probably generating an error about an unrecognised
6132 Similarly problems might occur with the period character (@samp{.})
6133 which is often allowed inside opcode names (and hence identifier names). So
6134 for example constructing a macro to build an opcode from a base name and a
6135 length specifier like this:
6138 .macro opcode base length
6143 and invoking it as @samp{opcode store l} will not create a @samp{store.l}
6144 instruction but instead generate some kind of error as the assembler tries to
6145 interpret the text @samp{\base.\length}.
6147 There are several possible ways around this problem:
6150 @item Insert white space
6151 If it is possible to use white space characters then this is the simplest
6160 @item Use @samp{\()}
6161 The string @samp{\()} can be used to separate the end of a macro argument from
6162 the following text. eg:
6165 .macro opcode base length
6170 @item Use the alternate macro syntax mode
6171 In the alternative macro syntax mode the ampersand character (@samp{&}) can be
6172 used as a separator. eg:
6182 Note: this problem of correctly identifying string parameters to pseudo ops
6183 also applies to the identifiers used in @code{.irp} (@pxref{Irp})
6184 and @code{.irpc} (@pxref{Irpc}) as well.
6187 @cindex @code{endm} directive
6188 Mark the end of a macro definition.
6191 @cindex @code{exitm} directive
6192 Exit early from the current macro definition.
6194 @cindex number of macros executed
6195 @cindex macros, count executed
6197 @command{@value{AS}} maintains a counter of how many macros it has
6198 executed in this pseudo-variable; you can copy that number to your
6199 output with @samp{\@@}, but @emph{only within a macro definition}.
6201 @item LOCAL @var{name} [ , @dots{} ]
6202 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
6203 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
6204 @xref{Altmacro,,@code{.altmacro}}.
6208 @section @code{.mri @var{val}}
6210 @cindex @code{mri} directive
6211 @cindex MRI mode, temporarily
6212 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
6213 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
6214 affects code assembled until the next @code{.mri} directive, or until the end
6215 of the file. @xref{M, MRI mode, MRI mode}.
6218 @section @code{.noaltmacro}
6219 Disable alternate macro mode. @xref{Altmacro}.
6222 @section @code{.nolist}
6224 @cindex @code{nolist} directive
6225 @cindex listing control, turning off
6226 Control (in conjunction with the @code{.list} directive) whether or
6227 not assembly listings are generated. These two directives maintain an
6228 internal counter (which is zero initially). @code{.list} increments the
6229 counter, and @code{.nolist} decrements it. Assembly listings are
6230 generated whenever the counter is greater than zero.
6233 @section @code{.nop [@var{size}]}
6235 @cindex @code{nop} directive
6236 @cindex filling memory with no-op instructions
6237 This directive emits no-op instructions. It is provided on all architectures,
6238 allowing the creation of architecture neutral tests involving actual code. The
6239 size of the generated instruction is target specific, but if the optional
6240 @var{size} argument is given and resolves to an absolute positive value at that
6241 point in assembly (no forward expressions allowed) then the fewest no-op
6242 instructions are emitted that equal or exceed a total @var{size} in bytes.
6243 @code{.nop} does affect the generation of DWARF debug line information.
6244 Some targets do not support using @code{.nop} with @var{size}.
6247 @section @code{.nops @var{size}[, @var{control}]}
6249 @cindex @code{nops} directive
6250 @cindex filling memory with no-op instructions
6251 This directive emits no-op instructions. It is specific to the Intel 80386 and
6252 AMD x86-64 targets. It takes a @var{size} argument and generates @var{size}
6253 bytes of no-op instructions. @var{size} must be absolute and positive. These
6254 bytes do not affect the generation of DWARF debug line information.
6256 The optional @var{control} argument specifies a size limit for a single no-op
6257 instruction. If not provided then a value of 0 is assumed. The valid values
6258 of @var{control} are between 0 and 4 in 16-bit mode, between 0 and 7 when
6259 tuning for older processors in 32-bit mode, between 0 and 11 in 64-bit mode or
6260 when tuning for newer processors in 32-bit mode. When 0 is used, the no-op
6261 instruction size limit is set to the maximum supported size.
6264 @section @code{.octa @var{bignums}}
6266 @c FIXME: double size emitted for "octa" on some? Or warn?
6267 @cindex @code{octa} directive
6268 @cindex integer, 16-byte
6269 @cindex sixteen byte integer
6270 This directive expects zero or more bignums, separated by commas. For each
6271 bignum, it emits a 16-byte integer.
6273 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
6274 hence @emph{octa}-word for 16 bytes.
6277 @section @code{.offset @var{loc}}
6279 @cindex @code{offset} directive
6280 Set the location counter to @var{loc} in the absolute section. @var{loc} must
6281 be an absolute expression. This directive may be useful for defining
6282 symbols with absolute values. Do not confuse it with the @code{.org}
6286 @section @code{.org @var{new-lc} , @var{fill}}
6288 @cindex @code{org} directive
6289 @cindex location counter, advancing
6290 @cindex advancing location counter
6291 @cindex current address, advancing
6292 Advance the location counter of the current section to
6293 @var{new-lc}. @var{new-lc} is either an absolute expression or an
6294 expression with the same section as the current subsection. That is,
6295 you can't use @code{.org} to cross sections: if @var{new-lc} has the
6296 wrong section, the @code{.org} directive is ignored. To be compatible
6297 with former assemblers, if the section of @var{new-lc} is absolute,
6298 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
6299 is the same as the current subsection.
6301 @code{.org} may only increase the location counter, or leave it
6302 unchanged; you cannot use @code{.org} to move the location counter
6305 @c double negative used below "not undefined" because this is a specific
6306 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
6307 @c section. doc@cygnus.com 18feb91
6308 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
6309 may not be undefined. If you really detest this restriction we eagerly await
6310 a chance to share your improved assembler.
6312 Beware that the origin is relative to the start of the section, not
6313 to the start of the subsection. This is compatible with other
6314 people's assemblers.
6316 When the location counter (of the current subsection) is advanced, the
6317 intervening bytes are filled with @var{fill} which should be an
6318 absolute expression. If the comma and @var{fill} are omitted,
6319 @var{fill} defaults to zero.
6322 @section @code{.p2align[wl] [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
6324 @cindex padding the location counter given a power of two
6325 @cindex @code{p2align} directive
6326 Pad the location counter (in the current subsection) to a particular
6327 storage boundary. The first expression (which must be absolute) is the
6328 number of low-order zero bits the location counter must have after
6329 advancement. For example @samp{.p2align 3} advances the location
6330 counter until it is a multiple of 8. If the location counter is already a
6331 multiple of 8, no change is needed. If the expression is omitted then a
6332 default value of 0 is used, effectively disabling alignment requirements.
6334 The second expression (also absolute) gives the fill value to be stored in the
6335 padding bytes. It (and the comma) may be omitted. If it is omitted, the
6336 padding bytes are normally zero. However, on most systems, if the section is
6337 marked as containing code and the fill value is omitted, the space is filled
6338 with no-op instructions.
6340 The third expression is also absolute, and is also optional. If it is present,
6341 it is the maximum number of bytes that should be skipped by this alignment
6342 directive. If doing the alignment would require skipping more bytes than the
6343 specified maximum, then the alignment is not done at all. You can omit the
6344 fill value (the second argument) entirely by simply using two commas after the
6345 required alignment; this can be useful if you want the alignment to be filled
6346 with no-op instructions when appropriate.
6348 @cindex @code{p2alignw} directive
6349 @cindex @code{p2alignl} directive
6350 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
6351 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
6352 pattern as a two byte word value. The @code{.p2alignl} directives treats the
6353 fill pattern as a four byte longword value. For example, @code{.p2alignw
6354 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
6355 filled in with the value 0x368d (the exact placement of the bytes depends upon
6356 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
6361 @section @code{.popsection}
6363 @cindex @code{popsection} directive
6364 @cindex Section Stack
6365 This is one of the ELF section stack manipulation directives. The others are
6366 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
6367 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
6370 This directive replaces the current section (and subsection) with the top
6371 section (and subsection) on the section stack. This section is popped off the
6377 @section @code{.previous}
6379 @cindex @code{previous} directive
6380 @cindex Section Stack
6381 This is one of the ELF section stack manipulation directives. The others are
6382 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
6383 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
6384 (@pxref{PopSection}).
6386 This directive swaps the current section (and subsection) with most recently
6387 referenced section/subsection pair prior to this one. Multiple
6388 @code{.previous} directives in a row will flip between two sections (and their
6389 subsections). For example:
6401 Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
6407 # Now in section A subsection 1
6411 # Now in section B subsection 0
6414 # Now in section B subsection 1
6417 # Now in section B subsection 0
6421 Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
6422 section B and 0x9abc into subsection 1 of section B.
6424 In terms of the section stack, this directive swaps the current section with
6425 the top section on the section stack.
6429 @section @code{.print @var{string}}
6431 @cindex @code{print} directive
6432 @command{@value{AS}} will print @var{string} on the standard output during
6433 assembly. You must put @var{string} in double quotes.
6437 @section @code{.protected @var{names}}
6439 @cindex @code{protected} directive
6441 This is one of the ELF visibility directives. The other two are
6442 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
6444 This directive overrides the named symbols default visibility (which is set by
6445 their binding: local, global or weak). The directive sets the visibility to
6446 @code{protected} which means that any references to the symbols from within the
6447 components that defines them must be resolved to the definition in that
6448 component, even if a definition in another component would normally preempt
6453 @section @code{.psize @var{lines} , @var{columns}}
6455 @cindex @code{psize} directive
6456 @cindex listing control: paper size
6457 @cindex paper size, for listings
6458 Use this directive to declare the number of lines---and, optionally, the
6459 number of columns---to use for each page, when generating listings.
6461 If you do not use @code{.psize}, listings use a default line-count
6462 of 60. You may omit the comma and @var{columns} specification; the
6463 default width is 200 columns.
6465 @command{@value{AS}} generates formfeeds whenever the specified number of
6466 lines is exceeded (or whenever you explicitly request one, using
6469 If you specify @var{lines} as @code{0}, no formfeeds are generated save
6470 those explicitly specified with @code{.eject}.
6473 @section @code{.purgem @var{name}}
6475 @cindex @code{purgem} directive
6476 Undefine the macro @var{name}, so that later uses of the string will not be
6477 expanded. @xref{Macro}.
6481 @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]}
6483 @cindex @code{pushsection} directive
6484 @cindex Section Stack
6485 This is one of the ELF section stack manipulation directives. The others are
6486 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
6487 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6490 This directive pushes the current section (and subsection) onto the
6491 top of the section stack, and then replaces the current section and
6492 subsection with @code{name} and @code{subsection}. The optional
6493 @code{flags}, @code{type} and @code{arguments} are treated the same
6494 as in the @code{.section} (@pxref{Section}) directive.
6498 @section @code{.quad @var{bignums}}
6500 @cindex @code{quad} directive
6501 @code{.quad} expects zero or more bignums, separated by commas. For
6502 each bignum, it emits
6504 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
6505 warning message; and just takes the lowest order 8 bytes of the bignum.
6506 @cindex eight-byte integer
6507 @cindex integer, 8-byte
6509 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
6510 hence @emph{quad}-word for 8 bytes.
6513 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
6514 warning message; and just takes the lowest order 16 bytes of the bignum.
6515 @cindex sixteen-byte integer
6516 @cindex integer, 16-byte
6520 @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
6522 @cindex @code{reloc} directive
6523 Generate a relocation at @var{offset} of type @var{reloc_name} with value
6524 @var{expression}. If @var{offset} is a number, the relocation is generated in
6525 the current section. If @var{offset} is an expression that resolves to a
6526 symbol plus offset, the relocation is generated in the given symbol's section.
6527 @var{expression}, if present, must resolve to a symbol plus addend or to an
6528 absolute value, but note that not all targets support an addend. e.g. ELF REL
6529 targets such as i386 store an addend in the section contents rather than in the
6530 relocation. This low level interface does not support addends stored in the
6534 @section @code{.rept @var{count}}
6536 @cindex @code{rept} directive
6537 Repeat the sequence of lines between the @code{.rept} directive and the next
6538 @code{.endr} directive @var{count} times.
6540 For example, assembling
6548 is equivalent to assembling
6556 A count of zero is allowed, but nothing is generated. Negative counts are not
6557 allowed and if encountered will be treated as if they were zero.
6560 @section @code{.sbttl "@var{subheading}"}
6562 @cindex @code{sbttl} directive
6563 @cindex subtitles for listings
6564 @cindex listing control: subtitle
6565 Use @var{subheading} as the title (third line, immediately after the
6566 title line) when generating assembly listings.
6568 This directive affects subsequent pages, as well as the current page if
6569 it appears within ten lines of the top of a page.
6573 @section @code{.scl @var{class}}
6575 @cindex @code{scl} directive
6576 @cindex symbol storage class (COFF)
6577 @cindex COFF symbol storage class
6578 Set the storage-class value for a symbol. This directive may only be
6579 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
6580 whether a symbol is static or external, or it may record further
6581 symbolic debugging information.
6586 @section @code{.section @var{name}}
6588 @cindex named section
6589 Use the @code{.section} directive to assemble the following code into a section
6592 This directive is only supported for targets that actually support arbitrarily
6593 named sections; on @code{a.out} targets, for example, it is not accepted, even
6594 with a standard @code{a.out} section name.
6598 @c only print the extra heading if both COFF and ELF are set
6599 @subheading COFF Version
6602 @cindex @code{section} directive (COFF version)
6603 For COFF targets, the @code{.section} directive is used in one of the following
6607 .section @var{name}[, "@var{flags}"]
6608 .section @var{name}[, @var{subsection}]
6611 If the optional argument is quoted, it is taken as flags to use for the
6612 section. Each flag is a single character. The following flags are recognized:
6616 bss section (uninitialized data)
6618 section is not loaded
6624 exclude section from linking
6630 shared section (meaningful for PE targets)
6632 ignored. (For compatibility with the ELF version)
6634 section is not readable (meaningful for PE targets)
6636 single-digit power-of-two section alignment (GNU extension)
6639 If no flags are specified, the default flags depend upon the section name. If
6640 the section name is not recognized, the default will be for the section to be
6641 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
6642 from the section, rather than adding them, so if they are used on their own it
6643 will be as if no flags had been specified at all.
6645 If the optional argument to the @code{.section} directive is not quoted, it is
6646 taken as a subsection number (@pxref{Sub-Sections}).
6651 @c only print the extra heading if both COFF and ELF are set
6652 @subheading ELF Version
6655 @cindex Section Stack
6656 This is one of the ELF section stack manipulation directives. The others are
6657 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
6658 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
6659 @code{.previous} (@pxref{Previous}).
6661 @cindex @code{section} directive (ELF version)
6662 For ELF targets, the @code{.section} directive is used like this:
6665 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]]
6668 @anchor{Section Name Substitutions}
6669 @kindex --sectname-subst
6670 @cindex section name substitution
6671 If the @samp{--sectname-subst} command-line option is provided, the @var{name}
6672 argument may contain a substitution sequence. Only @code{%S} is supported
6673 at the moment, and substitutes the current section name. For example:
6676 .macro exception_code
6677 .section %S.exception
6678 [exception code here]
6693 The two @code{exception_code} invocations above would create the
6694 @code{.text.exception} and @code{.init.exception} sections respectively.
6695 This is useful e.g. to discriminate between ancillary sections that are
6696 tied to setup code to be discarded after use from ancillary sections that
6697 need to stay resident without having to define multiple @code{exception_code}
6698 macros just for that purpose.
6700 The optional @var{flags} argument is a quoted string which may contain any
6701 combination of the following characters:
6705 section is allocatable
6707 section is a GNU_MBIND section
6709 section is excluded from executable and shared library.
6711 section references a symbol defined in another section (the linked-to
6712 section) in the same file.
6716 section is executable
6718 section is mergeable
6720 section contains zero terminated strings
6722 section is a member of a section group
6724 section is used for thread-local-storage
6726 section is a member of the previously-current section's group, if any
6728 retained section (apply SHF_GNU_RETAIN to prevent linker garbage
6729 collection, GNU ELF extension)
6730 @item @code{<number>}
6731 a numeric value indicating the bits to be set in the ELF section header's flags
6732 field. Note - if one or more of the alphabetic characters described above is
6733 also included in the flags field, their bit values will be ORed into the
6735 @item @code{<target specific>}
6736 some targets extend this list with their own flag characters
6739 Note - once a section's flags have been set they cannot be changed. There are
6740 a few exceptions to this rule however. Processor and application specific
6741 flags can be added to an already defined section. The @code{.interp},
6742 @code{.strtab} and @code{.symtab} sections can have the allocate flag
6743 (@code{a}) set after they are initially defined, and the @code{.note-GNU-stack}
6744 section may have the executable (@code{x}) flag added. Also note that the
6745 @code{.attach_to_group} directive can be used to add a section to a group even
6746 if the section was not originally declared to be part of that group.
6748 The optional @var{type} argument may contain one of the following constants:
6752 section contains data
6754 section does not contain data (i.e., section only occupies space)
6756 section contains data which is used by things other than the program
6758 section contains an array of pointers to init functions
6760 section contains an array of pointers to finish functions
6761 @item @@preinit_array
6762 section contains an array of pointers to pre-init functions
6763 @item @@@code{<number>}
6764 a numeric value to be set as the ELF section header's type field.
6765 @item @@@code{<target specific>}
6766 some targets extend this list with their own types
6769 Many targets only support the first three section types. The type may be
6770 enclosed in double quotes if necessary.
6772 Note on targets where the @code{@@} character is the start of a comment (eg
6773 ARM) then another character is used instead. For example the ARM port uses the
6776 Note - some sections, eg @code{.text} and @code{.data} are considered to be
6777 special and have fixed types. Any attempt to declare them with a different
6778 type will generate an error from the assembler.
6780 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
6781 be specified as well as an extra argument---@var{entsize}---like this:
6784 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
6787 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
6788 constants, each @var{entsize} octets long. Sections with both @code{M} and
6789 @code{S} must contain zero terminated strings where each character is
6790 @var{entsize} bytes long. The linker may remove duplicates within sections with
6791 the same name, same entity size and same flags. @var{entsize} must be an
6792 absolute expression. For sections with both @code{M} and @code{S}, a string
6793 which is a suffix of a larger string is considered a duplicate. Thus
6794 @code{"def"} will be merged with @code{"abcdef"}; A reference to the first
6795 @code{"def"} will be changed to a reference to @code{"abcdef"+3}.
6797 If @var{flags} contains the @code{o} flag, then the @var{type} argument
6798 must be present along with an additional field like this:
6801 .section @var{name},"@var{flags}"o,@@@var{type},@var{SymbolName}|@var{SectionIndex}
6804 The @var{SymbolName} field specifies the symbol name which the section
6805 references. Alternatively a numeric @var{SectionIndex} can be provided. This
6806 is not generally a good idea as section indicies are rarely known at assembly
6807 time, but the facility is provided for testing purposes. An index of zero is
6808 allowed. It indicates that the linked-to section has already been discarded.
6810 Note: If both the @var{M} and @var{o} flags are present, then the fields
6811 for the Merge flag should come first, like this:
6814 .section @var{name},"@var{flags}"Mo,@@@var{type},@var{entsize},@var{SymbolName}
6817 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
6818 be present along with an additional field like this:
6821 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
6824 The @var{GroupName} field specifies the name of the section group to which this
6825 particular section belongs. The optional linkage field can contain:
6829 indicates that only one copy of this section should be retained
6834 Note: if both the @var{M} and @var{G} flags are present then the fields for
6835 the Merge flag should come first, like this:
6838 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
6841 If both @code{o} flag and @code{G} flag are present, then the
6842 @var{SymbolName} field for @code{o} comes first, like this:
6845 .section @var{name},"@var{flags}"oG,@@@var{type},@var{SymbolName},@var{GroupName}[,@var{linkage}]
6848 If @var{flags} contains the @code{?} symbol then it may not also contain the
6849 @code{G} symbol and the @var{GroupName} or @var{linkage} fields should not be
6850 present. Instead, @code{?} says to consider the section that's current before
6851 this directive. If that section used @code{G}, then the new section will use
6852 @code{G} with those same @var{GroupName} and @var{linkage} fields implicitly.
6853 If not, then the @code{?} symbol has no effect.
6855 The optional @var{unique,@code{<number>}} argument must come last. It
6856 assigns @var{@code{<number>}} as a unique section ID to distinguish
6857 different sections with the same section name like these:
6860 .section @var{name},"@var{flags}",@@@var{type},@var{unique,@code{<number>}}
6861 .section @var{name},"@var{flags}"G,@@@var{type},@var{GroupName},[@var{linkage}],@var{unique,@code{<number>}}
6862 .section @var{name},"@var{flags}"MG,@@@var{type},@var{entsize},@var{GroupName}[,@var{linkage}],@var{unique,@code{<number>}}
6865 The valid values of @var{@code{<number>}} are between 0 and 4294967295.
6867 If no flags are specified, the default flags depend upon the section name. If
6868 the section name is not recognized, the default will be for the section to have
6869 none of the above flags: it will not be allocated in memory, nor writable, nor
6870 executable. The section will contain data.
6872 For ELF targets, the assembler supports another type of @code{.section}
6873 directive for compatibility with the Solaris assembler:
6876 .section "@var{name}"[, @var{flags}...]
6879 Note that the section name is quoted. There may be a sequence of comma
6884 section is allocatable
6888 section is executable
6890 section is excluded from executable and shared library.
6892 section is used for thread local storage
6895 This directive replaces the current section and subsection. See the
6896 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
6897 some examples of how this directive and the other section stack directives
6903 @section @code{.set @var{symbol}, @var{expression}}
6905 @cindex @code{set} directive
6906 @cindex symbol value, setting
6907 Set the value of @var{symbol} to @var{expression}. This
6908 changes @var{symbol}'s value and type to conform to
6909 @var{expression}. If @var{symbol} was flagged as external, it remains
6910 flagged (@pxref{Symbol Attributes}).
6912 You may @code{.set} a symbol many times in the same assembly provided that the
6913 values given to the symbol are constants. Values that are based on expressions
6914 involving other symbols are allowed, but some targets may restrict this to only
6915 being done once per assembly. This is because those targets do not set the
6916 addresses of symbols at assembly time, but rather delay the assignment until a
6917 final link is performed. This allows the linker a chance to change the code in
6918 the files, changing the location of, and the relative distance between, various
6921 If you @code{.set} a global symbol, the value stored in the object
6922 file is the last value stored into it.
6925 On Z80 @code{set} is a real instruction, use @code{.set} or
6926 @samp{@var{symbol} defl @var{expression}} instead.
6930 @section @code{.short @var{expressions}}
6932 @cindex @code{short} directive
6934 @code{.short} is normally the same as @samp{.word}.
6935 @xref{Word,,@code{.word}}.
6937 In some configurations, however, @code{.short} and @code{.word} generate
6938 numbers of different lengths. @xref{Machine Dependencies}.
6942 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
6945 This expects zero or more @var{expressions}, and emits
6946 a 16 bit number for each.
6951 @section @code{.single @var{flonums}}
6953 @cindex @code{single} directive
6954 @cindex floating point numbers (single)
6955 This directive assembles zero or more flonums, separated by commas. It
6956 has the same effect as @code{.float}.
6958 The exact kind of floating point numbers emitted depends on how
6959 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
6963 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
6964 numbers in @sc{ieee} format.
6970 @section @code{.size}
6972 This directive is used to set the size associated with a symbol.
6976 @c only print the extra heading if both COFF and ELF are set
6977 @subheading COFF Version
6980 @cindex @code{size} directive (COFF version)
6981 For COFF targets, the @code{.size} directive is only permitted inside
6982 @code{.def}/@code{.endef} pairs. It is used like this:
6985 .size @var{expression}
6992 @c only print the extra heading if both COFF and ELF are set
6993 @subheading ELF Version
6996 @cindex @code{size} directive (ELF version)
6997 For ELF targets, the @code{.size} directive is used like this:
7000 .size @var{name} , @var{expression}
7003 This directive sets the size associated with a symbol @var{name}.
7004 The size in bytes is computed from @var{expression} which can make use of label
7005 arithmetic. This directive is typically used to set the size of function
7010 @ifclear no-space-dir
7012 @section @code{.skip @var{size} [,@var{fill}]}
7014 @cindex @code{skip} directive
7015 @cindex filling memory
7016 This directive emits @var{size} bytes, each of value @var{fill}. Both
7017 @var{size} and @var{fill} are absolute expressions. If the comma and
7018 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
7023 @section @code{.sleb128 @var{expressions}}
7025 @cindex @code{sleb128} directive
7026 @var{sleb128} stands for ``signed little endian base 128.'' This is a
7027 compact, variable length representation of numbers used by the DWARF
7028 symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}.
7030 @ifclear no-space-dir
7032 @section @code{.space @var{size} [,@var{fill}]}
7034 @cindex @code{space} directive
7035 @cindex filling memory
7036 This directive emits @var{size} bytes, each of value @var{fill}. Both
7037 @var{size} and @var{fill} are absolute expressions. If the comma
7038 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
7043 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
7044 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
7045 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
7046 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
7054 @section @code{.stabd, .stabn, .stabs}
7056 @cindex symbolic debuggers, information for
7057 @cindex @code{stab@var{x}} directives
7058 There are three directives that begin @samp{.stab}.
7059 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
7060 The symbols are not entered in the @command{@value{AS}} hash table: they
7061 cannot be referenced elsewhere in the source file.
7062 Up to five fields are required:
7066 This is the symbol's name. It may contain any character except
7067 @samp{\000}, so is more general than ordinary symbol names. Some
7068 debuggers used to code arbitrarily complex structures into symbol names
7072 An absolute expression. The symbol's type is set to the low 8 bits of
7073 this expression. Any bit pattern is permitted, but @code{@value{LD}}
7074 and debuggers choke on silly bit patterns.
7077 An absolute expression. The symbol's ``other'' attribute is set to the
7078 low 8 bits of this expression.
7081 An absolute expression. The symbol's descriptor is set to the low 16
7082 bits of this expression.
7085 An absolute expression which becomes the symbol's value.
7088 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
7089 or @code{.stabs} statement, the symbol has probably already been created;
7090 you get a half-formed symbol in your object file. This is
7091 compatible with earlier assemblers!
7094 @cindex @code{stabd} directive
7095 @item .stabd @var{type} , @var{other} , @var{desc}
7097 The ``name'' of the symbol generated is not even an empty string.
7098 It is a null pointer, for compatibility. Older assemblers used a
7099 null pointer so they didn't waste space in object files with empty
7102 The symbol's value is set to the location counter,
7103 relocatably. When your program is linked, the value of this symbol
7104 is the address of the location counter when the @code{.stabd} was
7107 @cindex @code{stabn} directive
7108 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
7109 The name of the symbol is set to the empty string @code{""}.
7111 @cindex @code{stabs} directive
7112 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
7113 All five fields are specified.
7119 @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
7120 "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
7122 @cindex string, copying to object file
7123 @cindex string8, copying to object file
7124 @cindex string16, copying to object file
7125 @cindex string32, copying to object file
7126 @cindex string64, copying to object file
7127 @cindex @code{string} directive
7128 @cindex @code{string8} directive
7129 @cindex @code{string16} directive
7130 @cindex @code{string32} directive
7131 @cindex @code{string64} directive
7133 Copy the characters in @var{str} to the object file. You may specify more than
7134 one string to copy, separated by commas. Unless otherwise specified for a
7135 particular machine, the assembler marks the end of each string with a 0 byte.
7136 You can use any of the escape sequences described in @ref{Strings,,Strings}.
7138 The variants @code{string16}, @code{string32} and @code{string64} differ from
7139 the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
7140 copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
7141 are stored in target endianness byte order.
7147 .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
7148 .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
7153 @section @code{.struct @var{expression}}
7155 @cindex @code{struct} directive
7156 Switch to the absolute section, and set the section offset to @var{expression},
7157 which must be an absolute expression. You might use this as follows:
7166 This would define the symbol @code{field1} to have the value 0, the symbol
7167 @code{field2} to have the value 4, and the symbol @code{field3} to have the
7168 value 8. Assembly would be left in the absolute section, and you would need to
7169 use a @code{.section} directive of some sort to change to some other section
7170 before further assembly.
7174 @section @code{.subsection @var{name}}
7176 @cindex @code{subsection} directive
7177 @cindex Section Stack
7178 This is one of the ELF section stack manipulation directives. The others are
7179 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
7180 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
7183 This directive replaces the current subsection with @code{name}. The current
7184 section is not changed. The replaced subsection is put onto the section stack
7185 in place of the then current top of stack subsection.
7190 @section @code{.symver}
7191 @cindex @code{symver} directive
7192 @cindex symbol versioning
7193 @cindex versions of symbols
7194 Use the @code{.symver} directive to bind symbols to specific version nodes
7195 within a source file. This is only supported on ELF platforms, and is
7196 typically used when assembling files to be linked into a shared library.
7197 There are cases where it may make sense to use this in objects to be bound
7198 into an application itself so as to override a versioned symbol from a
7201 For ELF targets, the @code{.symver} directive can be used like this:
7203 .symver @var{name}, @var{name2@@nodename}[ ,@var{visibility}]
7205 If the original symbol @var{name} is defined within the file
7206 being assembled, the @code{.symver} directive effectively creates a symbol
7207 alias with the name @var{name2@@nodename}, and in fact the main reason that we
7208 just don't try and create a regular alias is that the @var{@@} character isn't
7209 permitted in symbol names. The @var{name2} part of the name is the actual name
7210 of the symbol by which it will be externally referenced. The name @var{name}
7211 itself is merely a name of convenience that is used so that it is possible to
7212 have definitions for multiple versions of a function within a single source
7213 file, and so that the compiler can unambiguously know which version of a
7214 function is being mentioned. The @var{nodename} portion of the alias should be
7215 the name of a node specified in the version script supplied to the linker when
7216 building a shared library. If you are attempting to override a versioned
7217 symbol from a shared library, then @var{nodename} should correspond to the
7218 nodename of the symbol you are trying to override. The optional argument
7219 @var{visibility} updates the visibility of the original symbol. The valid
7220 visibilities are @code{local}, @code{hidden}, and @code{remove}. The
7221 @code{local} visibility makes the original symbol a local symbol
7222 (@pxref{Local}). The @code{hidden} visibility sets the visibility of the
7223 original symbol to @code{hidden} (@pxref{Hidden}). The @code{remove}
7224 visibility removes the original symbol from the symbol table. If visibility
7225 isn't specified, the original symbol is unchanged.
7227 If the symbol @var{name} is not defined within the file being assembled, all
7228 references to @var{name} will be changed to @var{name2@@nodename}. If no
7229 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
7232 Another usage of the @code{.symver} directive is:
7234 .symver @var{name}, @var{name2@@@@nodename}
7236 In this case, the symbol @var{name} must exist and be defined within
7237 the file being assembled. It is similar to @var{name2@@nodename}. The
7238 difference is @var{name2@@@@nodename} will also be used to resolve
7239 references to @var{name2} by the linker.
7241 The third usage of the @code{.symver} directive is:
7243 .symver @var{name}, @var{name2@@@@@@nodename}
7245 When @var{name} is not defined within the
7246 file being assembled, it is treated as @var{name2@@nodename}. When
7247 @var{name} is defined within the file being assembled, the symbol
7248 name, @var{name}, will be changed to @var{name2@@@@nodename}.
7253 @section @code{.tag @var{structname}}
7255 @cindex COFF structure debugging
7256 @cindex structure debugging, COFF
7257 @cindex @code{tag} directive
7258 This directive is generated by compilers to include auxiliary debugging
7259 information in the symbol table. It is only permitted inside
7260 @code{.def}/@code{.endef} pairs. Tags are used to link structure
7261 definitions in the symbol table with instances of those structures.
7265 @section @code{.text @var{subsection}}
7267 @cindex @code{text} directive
7268 Tells @command{@value{AS}} to assemble the following statements onto the end of
7269 the text subsection numbered @var{subsection}, which is an absolute
7270 expression. If @var{subsection} is omitted, subsection number zero
7274 @section @code{.title "@var{heading}"}
7276 @cindex @code{title} directive
7277 @cindex listing control: title line
7278 Use @var{heading} as the title (second line, immediately after the
7279 source file name and pagenumber) when generating assembly listings.
7281 This directive affects subsequent pages, as well as the current page if
7282 it appears within ten lines of the top of a page.
7286 @section @code{.tls_common @var{symbol}, @var{length}[, @var{alignment}]}
7288 @cindex @code{tls_common} directive
7289 This directive behaves in the same way as the @code{.comm} directive
7290 (@pxref{Comm}) except that @var{symbol} has type of STT_TLS instead of
7296 @section @code{.type}
7298 This directive is used to set the type of a symbol.
7302 @c only print the extra heading if both COFF and ELF are set
7303 @subheading COFF Version
7306 @cindex COFF symbol type
7307 @cindex symbol type, COFF
7308 @cindex @code{type} directive (COFF version)
7309 For COFF targets, this directive is permitted only within
7310 @code{.def}/@code{.endef} pairs. It is used like this:
7316 This records the integer @var{int} as the type attribute of a symbol table
7323 @c only print the extra heading if both COFF and ELF are set
7324 @subheading ELF Version
7327 @cindex ELF symbol type
7328 @cindex symbol type, ELF
7329 @cindex @code{type} directive (ELF version)
7330 For ELF targets, the @code{.type} directive is used like this:
7333 .type @var{name} , @var{type description}
7336 This sets the type of symbol @var{name} to be either a
7337 function symbol or an object symbol. There are five different syntaxes
7338 supported for the @var{type description} field, in order to provide
7339 compatibility with various other assemblers.
7341 Because some of the characters used in these syntaxes (such as @samp{@@} and
7342 @samp{#}) are comment characters for some architectures, some of the syntaxes
7343 below do not work on all architectures. The first variant will be accepted by
7344 the GNU assembler on all architectures so that variant should be used for
7345 maximum portability, if you do not need to assemble your code with other
7348 The syntaxes supported are:
7351 .type <name> STT_<TYPE_IN_UPPER_CASE>
7352 .type <name>,#<type>
7353 .type <name>,@@<type>
7354 .type <name>,%<type>
7355 .type <name>,"<type>"
7358 The types supported are:
7363 Mark the symbol as being a function name.
7366 @itemx gnu_indirect_function
7367 Mark the symbol as an indirect function when evaluated during reloc
7368 processing. (This is only supported on assemblers targeting GNU systems).
7372 Mark the symbol as being a data object.
7376 Mark the symbol as being a thread-local data object.
7380 Mark the symbol as being a common data object.
7384 Does not mark the symbol in any way. It is supported just for completeness.
7386 @item gnu_unique_object
7387 Marks the symbol as being a globally unique data object. The dynamic linker
7388 will make sure that in the entire process there is just one symbol with this
7389 name and type in use. (This is only supported on assemblers targeting GNU
7394 Changing between incompatible types other than from/to STT_NOTYPE will
7395 result in a diagnostic. An intermediate change to STT_NOTYPE will silence
7398 Note: Some targets support extra types in addition to those listed above.
7404 @section @code{.uleb128 @var{expressions}}
7406 @cindex @code{uleb128} directive
7407 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
7408 compact, variable length representation of numbers used by the DWARF
7409 symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}.
7413 @section @code{.val @var{addr}}
7415 @cindex @code{val} directive
7416 @cindex COFF value attribute
7417 @cindex value attribute, COFF
7418 This directive, permitted only within @code{.def}/@code{.endef} pairs,
7419 records the address @var{addr} as the value attribute of a symbol table
7425 @section @code{.version "@var{string}"}
7427 @cindex @code{version} directive
7428 This directive creates a @code{.note} section and places into it an ELF
7429 formatted note of type NT_VERSION. The note's name is set to @code{string}.
7434 @section @code{.vtable_entry @var{table}, @var{offset}}
7436 @cindex @code{vtable_entry} directive
7437 This directive finds or creates a symbol @code{table} and creates a
7438 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
7441 @section @code{.vtable_inherit @var{child}, @var{parent}}
7443 @cindex @code{vtable_inherit} directive
7444 This directive finds the symbol @code{child} and finds or creates the symbol
7445 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
7446 parent whose addend is the value of the child symbol. As a special case the
7447 parent name of @code{0} is treated as referring to the @code{*ABS*} section.
7451 @section @code{.warning "@var{string}"}
7452 @cindex warning directive
7453 Similar to the directive @code{.error}
7454 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
7457 @section @code{.weak @var{names}}
7459 @cindex @code{weak} directive
7460 This directive sets the weak attribute on the comma separated list of symbol
7461 @code{names}. If the symbols do not already exist, they will be created.
7463 On COFF targets other than PE, weak symbols are a GNU extension. This
7464 directive sets the weak attribute on the comma separated list of symbol
7465 @code{names}. If the symbols do not already exist, they will be created.
7467 On the PE target, weak symbols are supported natively as weak aliases.
7468 When a weak symbol is created that is not an alias, GAS creates an
7469 alternate symbol to hold the default value.
7472 @section @code{.weakref @var{alias}, @var{target}}
7474 @cindex @code{weakref} directive
7475 This directive creates an alias to the target symbol that enables the symbol to
7476 be referenced with weak-symbol semantics, but without actually making it weak.
7477 If direct references or definitions of the symbol are present, then the symbol
7478 will not be weak, but if all references to it are through weak references, the
7479 symbol will be marked as weak in the symbol table.
7481 The effect is equivalent to moving all references to the alias to a separate
7482 assembly source file, renaming the alias to the symbol in it, declaring the
7483 symbol as weak there, and running a reloadable link to merge the object files
7484 resulting from the assembly of the new source file and the old source file that
7485 had the references to the alias removed.
7487 The alias itself never makes to the symbol table, and is entirely handled
7488 within the assembler.
7491 @section @code{.word @var{expressions}}
7493 @cindex @code{word} directive
7494 This directive expects zero or more @var{expressions}, of any section,
7495 separated by commas.
7498 For each expression, @command{@value{AS}} emits a 32-bit number.
7501 For each expression, @command{@value{AS}} emits a 16-bit number.
7506 The size of the number emitted, and its byte order,
7507 depend on what target computer the assembly is for.
7510 @c on sparc the "special treatment to support compilers" doesn't
7511 @c happen---32-bit addressability, period; no long/short jumps.
7512 @ifset DIFF-TBL-KLUGE
7513 @cindex difference tables altered
7514 @cindex altered difference tables
7516 @emph{Warning: Special Treatment to support Compilers}
7520 Machines with a 32-bit address space, but that do less than 32-bit
7521 addressing, require the following special treatment. If the machine of
7522 interest to you does 32-bit addressing (or doesn't require it;
7523 @pxref{Machine Dependencies}), you can ignore this issue.
7526 In order to assemble compiler output into something that works,
7527 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
7528 Directives of the form @samp{.word sym1-sym2} are often emitted by
7529 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
7530 directive of the form @samp{.word sym1-sym2}, and the difference between
7531 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
7532 creates a @dfn{secondary jump table}, immediately before the next label.
7533 This secondary jump table is preceded by a short-jump to the
7534 first byte after the secondary table. This short-jump prevents the flow
7535 of control from accidentally falling into the new table. Inside the
7536 table is a long-jump to @code{sym2}. The original @samp{.word}
7537 contains @code{sym1} minus the address of the long-jump to
7540 If there were several occurrences of @samp{.word sym1-sym2} before the
7541 secondary jump table, all of them are adjusted. If there was a
7542 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
7543 long-jump to @code{sym4} is included in the secondary jump table,
7544 and the @code{.word} directives are adjusted to contain @code{sym3}
7545 minus the address of the long-jump to @code{sym4}; and so on, for as many
7546 entries in the original jump table as necessary.
7549 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
7550 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
7551 assembly language programmers.
7554 @c end DIFF-TBL-KLUGE
7556 @ifclear no-space-dir
7558 @section @code{.zero @var{size}}
7560 @cindex @code{zero} directive
7561 @cindex filling memory with zero bytes
7562 This directive emits @var{size} 0-valued bytes. @var{size} must be an absolute
7563 expression. This directive is actually an alias for the @samp{.skip} directive
7564 so it can take an optional second argument of the value to store in the bytes
7565 instead of zero. Using @samp{.zero} in this way would be confusing however.
7569 @section @code{.2byte @var{expression} [, @var{expression}]*}
7570 @cindex @code{2byte} directive
7571 @cindex two-byte integer
7572 @cindex integer, 2-byte
7574 This directive expects zero or more expressions, separated by commas. If there
7575 are no expressions then the directive does nothing. Otherwise each expression
7576 is evaluated in turn and placed in the next two bytes of the current output
7577 section, using the endian model of the target. If an expression will not fit
7578 in two bytes, a warning message is displayed and the least significant two
7579 bytes of the expression's value are used. If an expression cannot be evaluated
7580 at assembly time then relocations will be generated in order to compute the
7583 This directive does not apply any alignment before or after inserting the
7584 values. As a result of this, if relocations are generated, they may be
7585 different from those used for inserting values with a guaranteed alignment.
7588 @section @code{.4byte @var{expression} [, @var{expression}]*}
7589 @cindex @code{4byte} directive
7590 @cindex four-byte integer
7591 @cindex integer, 4-byte
7593 Like the @option{.2byte} directive, except that it inserts unaligned, four byte
7594 long values into the output.
7597 @section @code{.8byte @var{expression} [, @var{expression}]*}
7598 @cindex @code{8byte} directive
7599 @cindex eight-byte integer
7600 @cindex integer, 8-byte
7602 Like the @option{.2byte} directive, except that it inserts unaligned, eight
7603 byte long bignum values into the output.
7606 @section Deprecated Directives
7608 @cindex deprecated directives
7609 @cindex obsolescent directives
7610 One day these directives won't work.
7611 They are included for compatibility with older assemblers.
7618 @node Object Attributes
7619 @chapter Object Attributes
7620 @cindex object attributes
7622 @command{@value{AS}} assembles source files written for a specific architecture
7623 into object files for that architecture. But not all object files are alike.
7624 Many architectures support incompatible variations. For instance, floating
7625 point arguments might be passed in floating point registers if the object file
7626 requires hardware floating point support---or floating point arguments might be
7627 passed in integer registers if the object file supports processors with no
7628 hardware floating point unit. Or, if two objects are built for different
7629 generations of the same architecture, the combination may require the
7630 newer generation at run-time.
7632 This information is useful during and after linking. At link time,
7633 @command{@value{LD}} can warn about incompatible object files. After link
7634 time, tools like @command{gdb} can use it to process the linked file
7637 Compatibility information is recorded as a series of object attributes. Each
7638 attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
7639 string, and indicates who sets the meaning of the tag. The tag is an integer,
7640 and indicates what property the attribute describes. The value may be a string
7641 or an integer, and indicates how the property affects this object. Missing
7642 attributes are the same as attributes with a zero value or empty string value.
7644 Object attributes were developed as part of the ABI for the ARM Architecture.
7645 The file format is documented in @cite{ELF for the ARM Architecture}.
7648 * GNU Object Attributes:: @sc{gnu} Object Attributes
7649 * Defining New Object Attributes:: Defining New Object Attributes
7652 @node GNU Object Attributes
7653 @section @sc{gnu} Object Attributes
7655 The @code{.gnu_attribute} directive records an object attribute
7656 with vendor @samp{gnu}.
7658 Except for @samp{Tag_compatibility}, which has both an integer and a string for
7659 its value, @sc{gnu} attributes have a string value if the tag number is odd and
7660 an integer value if the tag number is even. The second bit (@code{@var{tag} &
7661 2} is set for architecture-independent attributes and clear for
7662 architecture-dependent ones.
7664 @subsection Common @sc{gnu} attributes
7666 These attributes are valid on all architectures.
7669 @item Tag_compatibility (32)
7670 The compatibility attribute takes an integer flag value and a vendor name. If
7671 the flag value is 0, the file is compatible with other toolchains. If it is 1,
7672 then the file is only compatible with the named toolchain. If it is greater
7673 than 1, the file can only be processed by other toolchains under some private
7674 arrangement indicated by the flag value and the vendor name.
7677 @subsection M680x0 Attributes
7680 @item Tag_GNU_M68K_ABI_FP (4)
7681 The floating-point ABI used by this object file. The value will be:
7685 0 for files not affected by the floating-point ABI.
7687 1 for files using double-precision hardware floating-point ABI.
7689 2 for files using the software floating-point ABI.
7693 @subsection MIPS Attributes
7696 @item Tag_GNU_MIPS_ABI_FP (4)
7697 The floating-point ABI used by this object file. The value will be:
7701 0 for files not affected by the floating-point ABI.
7703 1 for files using the hardware floating-point ABI with a standard
7704 double-precision FPU.
7706 2 for files using the hardware floating-point ABI with a single-precision FPU.
7708 3 for files using the software floating-point ABI.
7710 4 for files using the deprecated hardware floating-point ABI which used 64-bit
7711 floating-point registers, 32-bit general-purpose registers and increased the
7712 number of callee-saved floating-point registers.
7714 5 for files using the hardware floating-point ABI with a double-precision FPU
7715 with either 32-bit or 64-bit floating-point registers and 32-bit
7716 general-purpose registers.
7718 6 for files using the hardware floating-point ABI with 64-bit floating-point
7719 registers and 32-bit general-purpose registers.
7721 7 for files using the hardware floating-point ABI with 64-bit floating-point
7722 registers, 32-bit general-purpose registers and a rule that forbids the
7723 direct use of odd-numbered single-precision floating-point registers.
7727 @subsection PowerPC Attributes
7730 @item Tag_GNU_Power_ABI_FP (4)
7731 The floating-point ABI used by this object file. The value will be:
7735 0 for files not affected by the floating-point ABI.
7737 1 for files using double-precision hardware floating-point ABI.
7739 2 for files using the software floating-point ABI.
7741 3 for files using single-precision hardware floating-point ABI.
7744 @item Tag_GNU_Power_ABI_Vector (8)
7745 The vector ABI used by this object file. The value will be:
7749 0 for files not affected by the vector ABI.
7751 1 for files using general purpose registers to pass vectors.
7753 2 for files using AltiVec registers to pass vectors.
7755 3 for files using SPE registers to pass vectors.
7759 @subsection IBM z Systems Attributes
7762 @item Tag_GNU_S390_ABI_Vector (8)
7763 The vector ABI used by this object file. The value will be:
7767 0 for files not affected by the vector ABI.
7769 1 for files using software vector ABI.
7771 2 for files using hardware vector ABI.
7775 @subsection MSP430 Attributes
7778 @item Tag_GNU_MSP430_Data_Region (4)
7779 The data region used by this object file. The value will be:
7783 0 for files not using the large memory model.
7785 1 for files which have been compiled with the condition that all
7786 data is in the lower memory region, i.e. below address 0x10000.
7788 2 for files which allow data to be placed in the full 20-bit memory range.
7792 @node Defining New Object Attributes
7793 @section Defining New Object Attributes
7795 If you want to define a new @sc{gnu} object attribute, here are the places you
7796 will need to modify. New attributes should be discussed on the @samp{binutils}
7801 This manual, which is the official register of attributes.
7803 The header for your architecture @file{include/elf}, to define the tag.
7805 The @file{bfd} support file for your architecture, to merge the attribute
7806 and issue any appropriate link warnings.
7808 Test cases in @file{ld/testsuite} for merging and link warnings.
7810 @file{binutils/readelf.c} to display your attribute.
7812 GCC, if you want the compiler to mark the attribute automatically.
7818 @node Machine Dependencies
7819 @chapter Machine Dependent Features
7821 @cindex machine dependencies
7822 The machine instruction sets are (almost by definition) different on
7823 each machine where @command{@value{AS}} runs. Floating point representations
7824 vary as well, and @command{@value{AS}} often supports a few additional
7825 directives or command-line options for compatibility with other
7826 assemblers on a particular platform. Finally, some versions of
7827 @command{@value{AS}} support special pseudo-instructions for branch
7830 This chapter discusses most of these differences, though it does not
7831 include details on any machine's instruction set. For details on that
7832 subject, see the hardware manufacturer's manual.
7836 * AArch64-Dependent:: AArch64 Dependent Features
7839 * Alpha-Dependent:: Alpha Dependent Features
7842 * ARC-Dependent:: ARC Dependent Features
7845 * ARM-Dependent:: ARM Dependent Features
7848 * AVR-Dependent:: AVR Dependent Features
7851 * Blackfin-Dependent:: Blackfin Dependent Features
7854 * BPF-Dependent:: BPF Dependent Features
7857 * CR16-Dependent:: CR16 Dependent Features
7860 * CRIS-Dependent:: CRIS Dependent Features
7863 * C-SKY-Dependent:: C-SKY Dependent Features
7866 * D10V-Dependent:: D10V Dependent Features
7869 * D30V-Dependent:: D30V Dependent Features
7872 * Epiphany-Dependent:: EPIPHANY Dependent Features
7875 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7878 * HPPA-Dependent:: HPPA Dependent Features
7881 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
7884 * IA-64-Dependent:: Intel IA-64 Dependent Features
7887 * IP2K-Dependent:: IP2K Dependent Features
7890 * LoongArch-Dependent:: LoongArch Dependent Features
7893 * LM32-Dependent:: LM32 Dependent Features
7896 * M32C-Dependent:: M32C Dependent Features
7899 * M32R-Dependent:: M32R Dependent Features
7902 * M68K-Dependent:: M680x0 Dependent Features
7905 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
7908 * S12Z-Dependent:: S12Z Dependent Features
7911 * Meta-Dependent :: Meta Dependent Features
7914 * MicroBlaze-Dependent:: MICROBLAZE Dependent Features
7917 * MIPS-Dependent:: MIPS Dependent Features
7920 * MMIX-Dependent:: MMIX Dependent Features
7923 * MSP430-Dependent:: MSP430 Dependent Features
7926 * NDS32-Dependent:: Andes NDS32 Dependent Features
7929 * NiosII-Dependent:: Altera Nios II Dependent Features
7932 * NS32K-Dependent:: NS32K Dependent Features
7935 * OpenRISC-Dependent:: OpenRISC 1000 Features
7938 * PDP-11-Dependent:: PDP-11 Dependent Features
7941 * PJ-Dependent:: picoJava Dependent Features
7944 * PPC-Dependent:: PowerPC Dependent Features
7947 * PRU-Dependent:: PRU Dependent Features
7950 * RISC-V-Dependent:: RISC-V Dependent Features
7953 * RL78-Dependent:: RL78 Dependent Features
7956 * RX-Dependent:: RX Dependent Features
7959 * S/390-Dependent:: IBM S/390 Dependent Features
7962 * SCORE-Dependent:: SCORE Dependent Features
7965 * SH-Dependent:: Renesas / SuperH SH Dependent Features
7968 * Sparc-Dependent:: SPARC Dependent Features
7971 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
7974 * TIC6X-Dependent :: TI TMS320C6x Dependent Features
7977 * TILE-Gx-Dependent :: Tilera TILE-Gx Dependent Features
7980 * TILEPro-Dependent :: Tilera TILEPro Dependent Features
7983 * V850-Dependent:: V850 Dependent Features
7986 * Vax-Dependent:: VAX Dependent Features
7989 * Visium-Dependent:: Visium Dependent Features
7992 * WebAssembly-Dependent:: WebAssembly Dependent Features
7995 * XGATE-Dependent:: XGATE Dependent Features
7998 * XSTORMY16-Dependent:: XStormy16 Dependent Features
8001 * Xtensa-Dependent:: Xtensa Dependent Features
8004 * Z80-Dependent:: Z80 Dependent Features
8007 * Z8000-Dependent:: Z8000 Dependent Features
8014 @c The following major nodes are *sections* in the GENERIC version, *chapters*
8015 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
8016 @c peculiarity: to preserve cross-references, there must be a node called
8017 @c "Machine Dependencies". Hence the conditional nodenames in each
8018 @c major node below. Node defaulting in makeinfo requires adjacency of
8019 @c node and sectioning commands; hence the repetition of @chapter BLAH
8020 @c in both conditional blocks.
8023 @include c-aarch64.texi
8027 @include c-alpha.texi
8043 @include c-bfin.texi
8051 @include c-cr16.texi
8055 @include c-cris.texi
8059 @include c-csky.texi
8064 @node Machine Dependencies
8065 @chapter Machine Dependent Features
8067 The machine instruction sets are different on each Renesas chip family,
8068 and there are also some syntax differences among the families. This
8069 chapter describes the specific @command{@value{AS}} features for each
8073 * H8/300-Dependent:: Renesas H8/300 Dependent Features
8074 * SH-Dependent:: Renesas SH Dependent Features
8081 @include c-d10v.texi
8085 @include c-d30v.texi
8089 @include c-epiphany.texi
8093 @include c-h8300.texi
8097 @include c-hppa.texi
8101 @include c-i386.texi
8105 @include c-ia64.texi
8109 @include c-ip2k.texi
8113 @include c-lm32.texi
8117 @include c-loongarch.texi
8121 @include c-m32c.texi
8125 @include c-m32r.texi
8129 @include c-m68k.texi
8133 @include c-m68hc11.texi
8137 @include c-s12z.texi
8141 @include c-metag.texi
8145 @include c-microblaze.texi
8149 @include c-mips.texi
8153 @include c-mmix.texi
8157 @include c-msp430.texi
8161 @include c-nds32.texi
8165 @include c-nios2.texi
8169 @include c-ns32k.texi
8173 @include c-or1k.texi
8177 @include c-pdp11.texi
8193 @include c-riscv.texi
8197 @include c-rl78.texi
8205 @include c-s390.texi
8209 @include c-score.texi
8217 @include c-sparc.texi
8221 @include c-tic54x.texi
8225 @include c-tic6x.texi
8229 @include c-tilegx.texi
8233 @include c-tilepro.texi
8237 @include c-v850.texi
8245 @include c-visium.texi
8249 @include c-wasm32.texi
8253 @include c-xgate.texi
8257 @include c-xstormy16.texi
8261 @include c-xtensa.texi
8273 @c reverse effect of @down at top of generic Machine-Dep chapter
8277 @node Reporting Bugs
8278 @chapter Reporting Bugs
8279 @cindex bugs in assembler
8280 @cindex reporting bugs in assembler
8282 Your bug reports play an essential role in making @command{@value{AS}} reliable.
8284 Reporting a bug may help you by bringing a solution to your problem, or it may
8285 not. But in any case the principal function of a bug report is to help the
8286 entire community by making the next version of @command{@value{AS}} work better.
8287 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
8289 In order for a bug report to serve its purpose, you must include the
8290 information that enables us to fix the bug.
8293 * Bug Criteria:: Have you found a bug?
8294 * Bug Reporting:: How to report bugs
8298 @section Have You Found a Bug?
8299 @cindex bug criteria
8301 If you are not sure whether you have found a bug, here are some guidelines:
8304 @cindex fatal signal
8305 @cindex assembler crash
8306 @cindex crash of assembler
8308 If the assembler gets a fatal signal, for any input whatever, that is a
8309 @command{@value{AS}} bug. Reliable assemblers never crash.
8311 @cindex error on valid input
8313 If @command{@value{AS}} produces an error message for valid input, that is a bug.
8315 @cindex invalid input
8317 If @command{@value{AS}} does not produce an error message for invalid input, that
8318 is a bug. However, you should note that your idea of ``invalid input'' might
8319 be our idea of ``an extension'' or ``support for traditional practice''.
8322 If you are an experienced user of assemblers, your suggestions for improvement
8323 of @command{@value{AS}} are welcome in any case.
8327 @section How to Report Bugs
8329 @cindex assembler bugs, reporting
8331 A number of companies and individuals offer support for @sc{gnu} products. If
8332 you obtained @command{@value{AS}} from a support organization, we recommend you
8333 contact that organization first.
8335 You can find contact information for many support companies and
8336 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
8340 In any event, we also recommend that you send bug reports for @command{@value{AS}}
8344 The fundamental principle of reporting bugs usefully is this:
8345 @strong{report all the facts}. If you are not sure whether to state a
8346 fact or leave it out, state it!
8348 Often people omit facts because they think they know what causes the problem
8349 and assume that some details do not matter. Thus, you might assume that the
8350 name of a symbol you use in an example does not matter. Well, probably it does
8351 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
8352 happens to fetch from the location where that name is stored in memory;
8353 perhaps, if the name were different, the contents of that location would fool
8354 the assembler into doing the right thing despite the bug. Play it safe and
8355 give a specific, complete example. That is the easiest thing for you to do,
8356 and the most helpful.
8358 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
8359 it is new to us. Therefore, always write your bug reports on the assumption
8360 that the bug has not been reported previously.
8362 Sometimes people give a few sketchy facts and ask, ``Does this ring a
8363 bell?'' This cannot help us fix a bug, so it is basically useless. We
8364 respond by asking for enough details to enable us to investigate.
8365 You might as well expedite matters by sending them to begin with.
8367 To enable us to fix the bug, you should include all these things:
8371 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
8372 it with the @samp{--version} argument.
8374 Without this, we will not know whether there is any point in looking for
8375 the bug in the current version of @command{@value{AS}}.
8378 Any patches you may have applied to the @command{@value{AS}} source.
8381 The type of machine you are using, and the operating system name and
8385 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
8389 The command arguments you gave the assembler to assemble your example and
8390 observe the bug. To guarantee you will not omit something important, list them
8391 all. A copy of the Makefile (or the output from make) is sufficient.
8393 If we were to try to guess the arguments, we would probably guess wrong
8394 and then we might not encounter the bug.
8397 A complete input file that will reproduce the bug. If the bug is observed when
8398 the assembler is invoked via a compiler, send the assembler source, not the
8399 high level language source. Most compilers will produce the assembler source
8400 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
8401 the options @samp{-v --save-temps}; this will save the assembler source in a
8402 file with an extension of @file{.s}, and also show you exactly how
8403 @command{@value{AS}} is being run.
8406 A description of what behavior you observe that you believe is
8407 incorrect. For example, ``It gets a fatal signal.''
8409 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
8410 will certainly notice it. But if the bug is incorrect output, we might not
8411 notice unless it is glaringly wrong. You might as well not give us a chance to
8414 Even if the problem you experience is a fatal signal, you should still say so
8415 explicitly. Suppose something strange is going on, such as, your copy of
8416 @command{@value{AS}} is out of sync, or you have encountered a bug in the C
8417 library on your system. (This has happened!) Your copy might crash and ours
8418 would not. If you told us to expect a crash, then when ours fails to crash, we
8419 would know that the bug was not happening for us. If you had not told us to
8420 expect a crash, then we would not be able to draw any conclusion from our
8424 If you wish to suggest changes to the @command{@value{AS}} source, send us context
8425 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
8426 option. Always send diffs from the old file to the new file. If you even
8427 discuss something in the @command{@value{AS}} source, refer to it by context, not
8430 The line numbers in our development sources will not match those in your
8431 sources. Your line numbers would convey no useful information to us.
8434 Here are some things that are not necessary:
8438 A description of the envelope of the bug.
8440 Often people who encounter a bug spend a lot of time investigating
8441 which changes to the input file will make the bug go away and which
8442 changes will not affect it.
8444 This is often time consuming and not very useful, because the way we
8445 will find the bug is by running a single example under the debugger
8446 with breakpoints, not by pure deduction from a series of examples.
8447 We recommend that you save your time for something else.
8449 Of course, if you can find a simpler example to report @emph{instead}
8450 of the original one, that is a convenience for us. Errors in the
8451 output will be easier to spot, running under the debugger will take
8452 less time, and so on.
8454 However, simplification is not vital; if you do not want to do this,
8455 report the bug anyway and send us the entire test case you used.
8458 A patch for the bug.
8460 A patch for the bug does help us if it is a good one. But do not omit
8461 the necessary information, such as the test case, on the assumption that
8462 a patch is all we need. We might see problems with your patch and decide
8463 to fix the problem another way, or we might not understand it at all.
8465 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
8466 construct an example that will make the program follow a certain path through
8467 the code. If you do not send us the example, we will not be able to construct
8468 one, so we will not be able to verify that the bug is fixed.
8470 And if we cannot understand what bug you are trying to fix, or why your
8471 patch should be an improvement, we will not install it. A test case will
8472 help us to understand.
8475 A guess about what the bug is or what it depends on.
8477 Such guesses are usually wrong. Even we cannot guess right about such
8478 things without first using the debugger to find the facts.
8481 @node Acknowledgements
8482 @chapter Acknowledgements
8484 If you have contributed to GAS and your name isn't listed here,
8485 it is not meant as a slight. We just don't know about it. Send mail to the
8486 maintainer, and we'll correct the situation. Currently
8488 the maintainer is Nick Clifton (email address @code{nickc@@redhat.com}).
8490 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
8493 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
8494 information and the 68k series machines, most of the preprocessing pass, and
8495 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
8497 K. Richard Pixley maintained GAS for a while, adding various enhancements and
8498 many bug fixes, including merging support for several processors, breaking GAS
8499 up to handle multiple object file format back ends (including heavy rewrite,
8500 testing, an integration of the coff and b.out back ends), adding configuration
8501 including heavy testing and verification of cross assemblers and file splits
8502 and renaming, converted GAS to strictly ANSI C including full prototypes, added
8503 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
8504 port (including considerable amounts of reverse engineering), a SPARC opcode
8505 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
8506 assertions and made them work, much other reorganization, cleanup, and lint.
8508 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
8509 in format-specific I/O modules.
8511 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
8512 has done much work with it since.
8514 The Intel 80386 machine description was written by Eliot Dresselhaus.
8516 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
8518 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
8519 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
8521 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
8522 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
8523 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
8524 support a.out format.
8526 Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
8527 tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
8528 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
8529 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
8532 John Gilmore built the AMD 29000 support, added @code{.include} support, and
8533 simplified the configuration of which versions accept which directives. He
8534 updated the 68k machine description so that Motorola's opcodes always produced
8535 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
8536 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
8537 cross-compilation support, and one bug in relaxation that took a week and
8538 required the proverbial one-bit fix.
8540 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
8541 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
8542 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
8543 PowerPC assembler, and made a few other minor patches.
8545 Steve Chamberlain made GAS able to generate listings.
8547 Hewlett-Packard contributed support for the HP9000/300.
8549 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
8550 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
8551 formats). This work was supported by both the Center for Software Science at
8552 the University of Utah and Cygnus Support.
8554 Support for ELF format files has been worked on by Mark Eichin of Cygnus
8555 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
8556 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
8557 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
8558 and some initial 64-bit support).
8560 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
8562 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
8563 support for openVMS/Alpha.
8565 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
8568 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
8569 Inc.@: added support for Xtensa processors.
8571 Several engineers at Cygnus Support have also provided many small bug fixes and
8572 configuration enhancements.
8574 Jon Beniston added support for the Lattice Mico32 architecture.
8576 Many others have contributed large or small bugfixes and enhancements. If
8577 you have contributed significant work and are not mentioned on this list, and
8578 want to be, let us know. Some of the history has been lost; we are not
8579 intentionally leaving anyone out.
8581 @node GNU Free Documentation License
8582 @appendix GNU Free Documentation License
8586 @unnumbered AS Index