1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright (C) 1991-2022 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{} 1991-2022 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{} 1991-2022 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 @itemx --compress-debug-sections=zstd
715 These options control how DWARF debug sections are compressed.
716 @option{--compress-debug-sections=none} is equivalent to
717 @option{--nocompress-debug-sections}.
718 @option{--compress-debug-sections=zlib} and
719 @option{--compress-debug-sections=zlib-gabi} are equivalent to
720 @option{--compress-debug-sections}.
721 @option{--compress-debug-sections=zlib-gnu} compresses DWARF debug sections
722 using the obsoleted zlib-gnu format. The debug sections are renamed to begin
724 @option{--compress-debug-sections=zstd} compresses DWARF debug
725 sections using zstd. Note - if compression would actually make a section
726 @emph{larger}, then it is not compressed nor renamed.
730 @item --nocompress-debug-sections
731 Do not compress DWARF debug sections. This is usually the default for all
732 targets except the x86/x86_64, but a configure time option can be used to
736 Ignored. This option is accepted for script compatibility with calls to
739 @item --debug-prefix-map @var{old}=@var{new}
740 When assembling files in directory @file{@var{old}}, record debugging
741 information describing them as in @file{@var{new}} instead.
743 @item --defsym @var{sym}=@var{value}
744 Define the symbol @var{sym} to be @var{value} before assembling the input file.
745 @var{value} must be an integer constant. As in C, a leading @samp{0x}
746 indicates a hexadecimal value, and a leading @samp{0} indicates an octal
747 value. The value of the symbol can be overridden inside a source file via the
748 use of a @code{.set} pseudo-op.
751 ``fast''---skip whitespace and comment preprocessing (assume source is
756 Generate debugging information for each assembler source line using whichever
757 debug format is preferred by the target. This currently means either STABS,
758 ECOFF or DWARF2. When the debug format is DWARF then a @code{.debug_info} and
759 @code{.debug_line} section is only emitted when the assembly file doesn't
763 Generate stabs debugging information for each assembler line. This
764 may help debugging assembler code, if the debugger can handle it.
767 Generate stabs debugging information for each assembler line, with GNU
768 extensions that probably only gdb can handle, and that could make other
769 debuggers crash or refuse to read your program. This
770 may help debugging assembler code. Currently the only GNU extension is
771 the location of the current working directory at assembling time.
774 Generate DWARF2 debugging information for each assembler line. This
775 may help debugging assembler code, if the debugger can handle it. Note---this
776 option is only supported by some targets, not all of them.
779 This option is the same as the @option{--gdwarf-2} option, except that it
780 allows for the possibility of the generation of extra debug information as per
781 version 3 of the DWARF specification. Note - enabling this option does not
782 guarantee the generation of any extra information, the choice to do so is on a
786 This option is the same as the @option{--gdwarf-2} option, except that it
787 allows for the possibility of the generation of extra debug information as per
788 version 4 of the DWARF specification. Note - enabling this option does not
789 guarantee the generation of any extra information, the choice to do so is on a
793 This option is the same as the @option{--gdwarf-2} option, except that it
794 allows for the possibility of the generation of extra debug information as per
795 version 5 of the DWARF specification. Note - enabling this option does not
796 guarantee the generation of any extra information, the choice to do so is on a
799 @item --gdwarf-sections
800 Instead of creating a .debug_line section, create a series of
801 .debug_line.@var{foo} sections where @var{foo} is the name of the
802 corresponding code section. For example a code section called @var{.text.func}
803 will have its dwarf line number information placed into a section called
804 @var{.debug_line.text.func}. If the code section is just called @var{.text}
805 then debug line section will still be called just @var{.debug_line} without any
808 @item --gdwarf-cie-version=@var{version}
809 Control which version of DWARF Common Information Entries (CIEs) are produced.
810 When this flag is not specificed the default is version 1, though some targets
811 can modify this default. Other possible values for @var{version} are 3 or 4.
814 @item --size-check=error
815 @itemx --size-check=warning
816 Issue an error or warning for invalid ELF .size directive.
818 @item --elf-stt-common=no
819 @itemx --elf-stt-common=yes
820 These options control whether the ELF assembler should generate common
821 symbols with the @code{STT_COMMON} type. The default can be controlled
822 by a configure option @option{--enable-elf-stt-common}.
824 @item --generate-missing-build-notes=yes
825 @itemx --generate-missing-build-notes=no
826 These options control whether the ELF assembler should generate GNU Build
827 attribute notes if none are present in the input sources.
828 The default can be controlled by the @option{--enable-generate-build-notes}
834 Print a summary of the command-line options and exit.
837 Print a summary of all target specific options and exit.
840 Add directory @var{dir} to the search list for @code{.include} directives.
843 Don't warn about signed overflow.
846 @ifclear DIFF-TBL-KLUGE
847 This option is accepted but has no effect on the @value{TARGET} family.
849 @ifset DIFF-TBL-KLUGE
850 Issue warnings when difference tables altered for long displacements.
855 Keep (in the symbol table) local symbols. These symbols start with
856 system-specific local label prefixes, typically @samp{.L} for ELF systems
857 or @samp{L} for traditional a.out systems.
862 @item --listing-lhs-width=@var{number}
863 Set the maximum width, in words, of the output data column for an assembler
864 listing to @var{number}.
866 @item --listing-lhs-width2=@var{number}
867 Set the maximum width, in words, of the output data column for continuation
868 lines in an assembler listing to @var{number}.
870 @item --listing-rhs-width=@var{number}
871 Set the maximum width of an input source line, as displayed in a listing, to
874 @item --listing-cont-lines=@var{number}
875 Set the maximum number of lines printed in a listing for a single line of input
878 @item --multibyte-handling=allow
879 @itemx --multibyte-handling=warn
880 @itemx --multibyte-handling=warn-sym-only
881 Controls how the assembler handles multibyte characters in the input. The
882 default (which can be restored by using the @option{allow} argument) is to
883 allow such characters without complaint. Using the @option{warn} argument will
884 make the assembler generate a warning message whenever any multibyte character
885 is encountered. Using the @option{warn-sym-only} argument will only cause a
886 warning to be generated when a symbol is defined with a name that contains
887 multibyte characters. (References to undefined symbols will not generate a
890 @item --no-pad-sections
891 Stop the assembler for padding the ends of output sections to the alignment
892 of that section. The default is to pad the sections, but this can waste space
893 which might be needed on targets which have tight memory constraints.
895 @item -o @var{objfile}
896 Name the object-file output from @command{@value{AS}} @var{objfile}.
899 Fold the data section into the text section.
902 @item --sectname-subst
903 Honor substitution sequences in section names.
905 @xref{Section Name Substitutions,,@code{.section @var{name}}}.
910 Print the maximum space (in bytes) and total time (in seconds) used by
913 @item --strip-local-absolute
914 Remove local absolute symbols from the outgoing symbol table.
918 Print the @command{as} version.
921 Print the @command{as} version and exit.
925 Suppress warning messages.
927 @item --fatal-warnings
928 Treat warnings as errors.
931 Don't suppress warning messages or treat them as errors.
940 Generate an object file even after errors.
942 @item -- | @var{files} @dots{}
943 Standard input, or source files to assemble.
951 @xref{AArch64 Options}, for the options available when @value{AS} is configured
952 for the 64-bit mode of the ARM Architecture (AArch64).
957 The following options are available when @value{AS} is configured for the
958 64-bit mode of the ARM Architecture (AArch64).
961 @include c-aarch64.texi
962 @c ended inside the included file
970 @xref{Alpha Options}, for the options available when @value{AS} is configured
971 for an Alpha processor.
976 The following options are available when @value{AS} is configured for an Alpha
980 @include c-alpha.texi
981 @c ended inside the included file
988 The following options are available when @value{AS} is configured for an ARC
992 @item -mcpu=@var{cpu}
993 This option selects the core processor variant.
995 Select either big-endian (-EB) or little-endian (-EL) output.
997 Enable Code Density extension instructions.
1002 The following options are available when @value{AS} is configured for the ARM
1006 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
1007 Specify which ARM processor variant is the target.
1008 @item -march=@var{architecture}[+@var{extension}@dots{}]
1009 Specify which ARM architecture variant is used by the target.
1010 @item -mfpu=@var{floating-point-format}
1011 Select which Floating Point architecture is the target.
1012 @item -mfloat-abi=@var{abi}
1013 Select which floating point ABI is in use.
1015 Enable Thumb only instruction decoding.
1016 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
1017 Select which procedure calling convention is in use.
1019 Select either big-endian (-EB) or little-endian (-EL) output.
1020 @item -mthumb-interwork
1021 Specify that the code has been generated with interworking between Thumb and
1024 Turns on CodeComposer Studio assembly syntax compatibility mode.
1026 Specify that PIC code has been generated.
1034 @xref{Blackfin Options}, for the options available when @value{AS} is
1035 configured for the Blackfin processor family.
1039 @c man begin OPTIONS
1040 The following options are available when @value{AS} is configured for
1041 the Blackfin processor family.
1043 @c man begin INCLUDE
1044 @include c-bfin.texi
1045 @c ended inside the included file
1053 @xref{BPF Options}, for the options available when @value{AS} is
1054 configured for the Linux kernel BPF processor family.
1058 @c man begin OPTIONS
1059 The following options are available when @value{AS} is configured for
1060 the Linux kernel BPF processor family.
1062 @c man begin INCLUDE
1064 @c ended inside the included file
1069 @c man begin OPTIONS
1071 See the info pages for documentation of the CRIS-specific options.
1077 @xref{C-SKY Options}, for the options available when @value{AS} is
1078 configured for the C-SKY processor family.
1082 @c man begin OPTIONS
1083 The following options are available when @value{AS} is configured for
1084 the C-SKY processor family.
1086 @c man begin INCLUDE
1087 @include c-csky.texi
1088 @c ended inside the included file
1094 The following options are available when @value{AS} is configured for
1097 @cindex D10V optimization
1098 @cindex optimization, D10V
1100 Optimize output by parallelizing instructions.
1105 The following options are available when @value{AS} is configured for a D30V
1108 @cindex D30V optimization
1109 @cindex optimization, D30V
1111 Optimize output by parallelizing instructions.
1115 Warn when nops are generated.
1117 @cindex D30V nops after 32-bit multiply
1119 Warn when a nop after a 32-bit multiply instruction is generated.
1125 The following options are available when @value{AS} is configured for the
1126 Adapteva EPIPHANY series.
1129 @xref{Epiphany Options}, for the options available when @value{AS} is
1130 configured for an Epiphany processor.
1134 @c man begin OPTIONS
1135 The following options are available when @value{AS} is configured for
1136 an Epiphany processor.
1138 @c man begin INCLUDE
1139 @include c-epiphany.texi
1140 @c ended inside the included file
1148 @xref{H8/300 Options}, for the options available when @value{AS} is configured
1149 for an H8/300 processor.
1153 @c man begin OPTIONS
1154 The following options are available when @value{AS} is configured for an H8/300
1157 @c man begin INCLUDE
1158 @include c-h8300.texi
1159 @c ended inside the included file
1167 @xref{i386-Options}, for the options available when @value{AS} is
1168 configured for an i386 processor.
1172 @c man begin OPTIONS
1173 The following options are available when @value{AS} is configured for
1176 @c man begin INCLUDE
1177 @include c-i386.texi
1178 @c ended inside the included file
1183 @c man begin OPTIONS
1185 The following options are available when @value{AS} is configured for the
1191 Specifies that the extended IP2022 instructions are allowed.
1194 Restores the default behaviour, which restricts the permitted instructions to
1195 just the basic IP2022 ones.
1201 The following options are available when @value{AS} is configured for the
1202 Renesas M32C and M16C processors.
1207 Assemble M32C instructions.
1210 Assemble M16C instructions (the default).
1213 Enable support for link-time relaxations.
1216 Support H'00 style hex constants in addition to 0x00 style.
1222 The following options are available when @value{AS} is configured for the
1223 Renesas M32R (formerly Mitsubishi M32R) series.
1228 Specify which processor in the M32R family is the target. The default
1229 is normally the M32R, but this option changes it to the M32RX.
1231 @item --warn-explicit-parallel-conflicts or --Wp
1232 Produce warning messages when questionable parallel constructs are
1235 @item --no-warn-explicit-parallel-conflicts or --Wnp
1236 Do not produce warning messages when questionable parallel constructs are
1243 The following options are available when @value{AS} is configured for the
1244 Motorola 68000 series.
1249 Shorten references to undefined symbols, to one word instead of two.
1251 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
1252 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
1253 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
1254 Specify what processor in the 68000 family is the target. The default
1255 is normally the 68020, but this can be changed at configuration time.
1257 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
1258 The target machine does (or does not) have a floating-point coprocessor.
1259 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
1260 the basic 68000 is not compatible with the 68881, a combination of the
1261 two can be specified, since it's possible to do emulation of the
1262 coprocessor instructions with the main processor.
1264 @item -m68851 | -mno-68851
1265 The target machine does (or does not) have a memory-management
1266 unit coprocessor. The default is to assume an MMU for 68020 and up.
1274 @xref{Nios II Options}, for the options available when @value{AS} is configured
1275 for an Altera Nios II processor.
1279 @c man begin OPTIONS
1280 The following options are available when @value{AS} is configured for an
1281 Altera Nios II processor.
1283 @c man begin INCLUDE
1284 @include c-nios2.texi
1285 @c ended inside the included file
1291 For details about the PDP-11 machine dependent features options,
1292 see @ref{PDP-11-Options}.
1295 @item -mpic | -mno-pic
1296 Generate position-independent (or position-dependent) code. The
1297 default is @option{-mpic}.
1300 @itemx -mall-extensions
1301 Enable all instruction set extensions. This is the default.
1303 @item -mno-extensions
1304 Disable all instruction set extensions.
1306 @item -m@var{extension} | -mno-@var{extension}
1307 Enable (or disable) a particular instruction set extension.
1310 Enable the instruction set extensions supported by a particular CPU, and
1311 disable all other extensions.
1313 @item -m@var{machine}
1314 Enable the instruction set extensions supported by a particular machine
1315 model, and disable all other extensions.
1321 The following options are available when @value{AS} is configured for
1322 a picoJava processor.
1326 @cindex PJ endianness
1327 @cindex endianness, PJ
1328 @cindex big endian output, PJ
1330 Generate ``big endian'' format output.
1332 @cindex little endian output, PJ
1334 Generate ``little endian'' format output.
1342 @xref{PRU Options}, for the options available when @value{AS} is configured
1343 for a PRU processor.
1347 @c man begin OPTIONS
1348 The following options are available when @value{AS} is configured for a
1351 @c man begin INCLUDE
1353 @c ended inside the included file
1358 The following options are available when @value{AS} is configured for the
1359 Motorola 68HC11 or 68HC12 series.
1363 @item -m68hc11 | -m68hc12 | -m68hcs12 | -mm9s12x | -mm9s12xg
1364 Specify what processor is the target. The default is
1365 defined by the configuration option when building the assembler.
1367 @item --xgate-ramoffset
1368 Instruct the linker to offset RAM addresses from S12X address space into
1369 XGATE address space.
1372 Specify to use the 16-bit integer ABI.
1375 Specify to use the 32-bit integer ABI.
1377 @item -mshort-double
1378 Specify to use the 32-bit double ABI.
1381 Specify to use the 64-bit double ABI.
1383 @item --force-long-branches
1384 Relative branches are turned into absolute ones. This concerns
1385 conditional branches, unconditional branches and branches to a
1388 @item -S | --short-branches
1389 Do not turn relative branches into absolute ones
1390 when the offset is out of range.
1392 @item --strict-direct-mode
1393 Do not turn the direct addressing mode into extended addressing mode
1394 when the instruction does not support direct addressing mode.
1396 @item --print-insn-syntax
1397 Print the syntax of instruction in case of error.
1399 @item --print-opcodes
1400 Print the list of instructions with syntax and then exit.
1402 @item --generate-example
1403 Print an example of instruction for each possible instruction and then exit.
1404 This option is only useful for testing @command{@value{AS}}.
1410 The following options are available when @command{@value{AS}} is configured
1411 for the SPARC architecture:
1414 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
1415 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
1416 Explicitly select a variant of the SPARC architecture.
1418 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
1419 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
1421 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
1422 UltraSPARC extensions.
1424 @item -xarch=v8plus | -xarch=v8plusa
1425 For compatibility with the Solaris v9 assembler. These options are
1426 equivalent to -Av8plus and -Av8plusa, respectively.
1429 Warn when the assembler switches to another architecture.
1434 The following options are available when @value{AS} is configured for the 'c54x
1439 Enable extended addressing mode. All addresses and relocations will assume
1440 extended addressing (usually 23 bits).
1441 @item -mcpu=@var{CPU_VERSION}
1442 Sets the CPU version being compiled for.
1443 @item -merrors-to-file @var{FILENAME}
1444 Redirect error output to a file, for broken systems which don't support such
1445 behaviour in the shell.
1450 @c man begin OPTIONS
1451 The following options are available when @value{AS} is configured for
1456 This option sets the largest size of an object that can be referenced
1457 implicitly with the @code{gp} register. It is only accepted for targets that
1458 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
1460 @cindex MIPS endianness
1461 @cindex endianness, MIPS
1462 @cindex big endian output, MIPS
1464 Generate ``big endian'' format output.
1466 @cindex little endian output, MIPS
1468 Generate ``little endian'' format output.
1486 Generate code for a particular MIPS Instruction Set Architecture level.
1487 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
1488 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
1489 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
1490 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips32r3},
1491 @samp{-mips32r5}, @samp{-mips32r6}, @samp{-mips64}, @samp{-mips64r2},
1492 @samp{-mips64r3}, @samp{-mips64r5}, and @samp{-mips64r6} correspond to generic
1493 MIPS V, MIPS32, MIPS32 Release 2, MIPS32 Release 3, MIPS32 Release 5, MIPS32
1494 Release 6, MIPS64, MIPS64 Release 2, MIPS64 Release 3, MIPS64 Release 5, and
1495 MIPS64 Release 6 ISA processors, respectively.
1497 @item -march=@var{cpu}
1498 Generate code for a particular MIPS CPU.
1500 @item -mtune=@var{cpu}
1501 Schedule and tune for a particular MIPS CPU.
1505 Cause nops to be inserted if the read of the destination register
1506 of an mfhi or mflo instruction occurs in the following two instructions.
1509 @itemx -mno-fix-rm7000
1510 Cause nops to be inserted if a dmult or dmultu instruction is
1511 followed by a load instruction.
1514 @itemx -mno-fix-r5900
1515 Do not attempt to schedule the preceding instruction into the delay slot
1516 of a branch instruction placed at the end of a short loop of six
1517 instructions or fewer and always schedule a @code{nop} instruction there
1518 instead. The short loop bug under certain conditions causes loops to
1519 execute only once or twice, due to a hardware bug in the R5900 chip.
1523 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
1524 section instead of the standard ELF .stabs sections.
1528 Control generation of @code{.pdr} sections.
1532 The register sizes are normally inferred from the ISA and ABI, but these
1533 flags force a certain group of registers to be treated as 32 bits wide at
1534 all times. @samp{-mgp32} controls the size of general-purpose registers
1535 and @samp{-mfp32} controls the size of floating-point registers.
1539 The register sizes are normally inferred from the ISA and ABI, but these
1540 flags force a certain group of registers to be treated as 64 bits wide at
1541 all times. @samp{-mgp64} controls the size of general-purpose registers
1542 and @samp{-mfp64} controls the size of floating-point registers.
1545 The register sizes are normally inferred from the ISA and ABI, but using
1546 this flag in combination with @samp{-mabi=32} enables an ABI variant
1547 which will operate correctly with floating-point registers which are
1551 @itemx -mno-odd-spreg
1552 Enable use of floating-point operations on odd-numbered single-precision
1553 registers when supported by the ISA. @samp{-mfpxx} implies
1554 @samp{-mno-odd-spreg}, otherwise the default is @samp{-modd-spreg}.
1558 Generate code for the MIPS 16 processor. This is equivalent to putting
1559 @code{.module mips16} at the start of the assembly file. @samp{-no-mips16}
1560 turns off this option.
1563 @itemx -mno-mips16e2
1564 Enable the use of MIPS16e2 instructions in MIPS16 mode. This is equivalent
1565 to putting @code{.module mips16e2} at the start of the assembly file.
1566 @samp{-mno-mips16e2} turns off this option.
1569 @itemx -mno-micromips
1570 Generate code for the microMIPS processor. This is equivalent to putting
1571 @code{.module micromips} at the start of the assembly file.
1572 @samp{-mno-micromips} turns off this option. This is equivalent to putting
1573 @code{.module nomicromips} at the start of the assembly file.
1576 @itemx -mno-smartmips
1577 Enables the SmartMIPS extension to the MIPS32 instruction set. This is
1578 equivalent to putting @code{.module smartmips} at the start of the assembly
1579 file. @samp{-mno-smartmips} turns off this option.
1583 Generate code for the MIPS-3D Application Specific Extension.
1584 This tells the assembler to accept MIPS-3D instructions.
1585 @samp{-no-mips3d} turns off this option.
1589 Generate code for the MDMX Application Specific Extension.
1590 This tells the assembler to accept MDMX instructions.
1591 @samp{-no-mdmx} turns off this option.
1595 Generate code for the DSP Release 1 Application Specific Extension.
1596 This tells the assembler to accept DSP Release 1 instructions.
1597 @samp{-mno-dsp} turns off this option.
1601 Generate code for the DSP Release 2 Application Specific Extension.
1602 This option implies @samp{-mdsp}.
1603 This tells the assembler to accept DSP Release 2 instructions.
1604 @samp{-mno-dspr2} turns off this option.
1608 Generate code for the DSP Release 3 Application Specific Extension.
1609 This option implies @samp{-mdsp} and @samp{-mdspr2}.
1610 This tells the assembler to accept DSP Release 3 instructions.
1611 @samp{-mno-dspr3} turns off this option.
1615 Generate code for the MIPS SIMD Architecture Extension.
1616 This tells the assembler to accept MSA instructions.
1617 @samp{-mno-msa} turns off this option.
1621 Generate code for the MIPS eXtended Physical Address (XPA) Extension.
1622 This tells the assembler to accept XPA instructions.
1623 @samp{-mno-xpa} turns off this option.
1627 Generate code for the MT Application Specific Extension.
1628 This tells the assembler to accept MT instructions.
1629 @samp{-mno-mt} turns off this option.
1633 Generate code for the MCU Application Specific Extension.
1634 This tells the assembler to accept MCU instructions.
1635 @samp{-mno-mcu} turns off this option.
1639 Generate code for the MIPS cyclic redundancy check (CRC) Application
1640 Specific Extension. This tells the assembler to accept CRC instructions.
1641 @samp{-mno-crc} turns off this option.
1645 Generate code for the Global INValidate (GINV) Application Specific
1646 Extension. This tells the assembler to accept GINV instructions.
1647 @samp{-mno-ginv} turns off this option.
1649 @item -mloongson-mmi
1650 @itemx -mno-loongson-mmi
1651 Generate code for the Loongson MultiMedia extensions Instructions (MMI)
1652 Application Specific Extension. This tells the assembler to accept MMI
1654 @samp{-mno-loongson-mmi} turns off this option.
1656 @item -mloongson-cam
1657 @itemx -mno-loongson-cam
1658 Generate code for the Loongson Content Address Memory (CAM) instructions.
1659 This tells the assembler to accept Loongson CAM instructions.
1660 @samp{-mno-loongson-cam} turns off this option.
1662 @item -mloongson-ext
1663 @itemx -mno-loongson-ext
1664 Generate code for the Loongson EXTensions (EXT) instructions.
1665 This tells the assembler to accept Loongson EXT instructions.
1666 @samp{-mno-loongson-ext} turns off this option.
1668 @item -mloongson-ext2
1669 @itemx -mno-loongson-ext2
1670 Generate code for the Loongson EXTensions R2 (EXT2) instructions.
1671 This option implies @samp{-mloongson-ext}.
1672 This tells the assembler to accept Loongson EXT2 instructions.
1673 @samp{-mno-loongson-ext2} turns off this option.
1677 Only use 32-bit instruction encodings when generating code for the
1678 microMIPS processor. This option inhibits the use of any 16-bit
1679 instructions. This is equivalent to putting @code{.set insn32} at
1680 the start of the assembly file. @samp{-mno-insn32} turns off this
1681 option. This is equivalent to putting @code{.set noinsn32} at the
1682 start of the assembly file. By default @samp{-mno-insn32} is
1683 selected, allowing all instructions to be used.
1685 @item --construct-floats
1686 @itemx --no-construct-floats
1687 The @samp{--no-construct-floats} option disables the construction of
1688 double width floating point constants by loading the two halves of the
1689 value into the two single width floating point registers that make up
1690 the double width register. By default @samp{--construct-floats} is
1691 selected, allowing construction of these floating point constants.
1693 @item --relax-branch
1694 @itemx --no-relax-branch
1695 The @samp{--relax-branch} option enables the relaxation of out-of-range
1696 branches. By default @samp{--no-relax-branch} is selected, causing any
1697 out-of-range branches to produce an error.
1699 @item -mignore-branch-isa
1700 @itemx -mno-ignore-branch-isa
1701 Ignore branch checks for invalid transitions between ISA modes. The
1702 semantics of branches does not provide for an ISA mode switch, so in
1703 most cases the ISA mode a branch has been encoded for has to be the
1704 same as the ISA mode of the branch's target label. Therefore GAS has
1705 checks implemented that verify in branch assembly that the two ISA
1706 modes match. @samp{-mignore-branch-isa} disables these checks. By
1707 default @samp{-mno-ignore-branch-isa} is selected, causing any invalid
1708 branch requiring a transition between ISA modes to produce an error.
1710 @item -mnan=@var{encoding}
1711 Select between the IEEE 754-2008 (@option{-mnan=2008}) or the legacy
1712 (@option{-mnan=legacy}) NaN encoding format. The latter is the default.
1715 @item --emulation=@var{name}
1716 This option was formerly used to switch between ELF and ECOFF output
1717 on targets like IRIX 5 that supported both. MIPS ECOFF support was
1718 removed in GAS 2.24, so the option now serves little purpose.
1719 It is retained for backwards compatibility.
1721 The available configuration names are: @samp{mipself}, @samp{mipslelf} and
1722 @samp{mipsbelf}. Choosing @samp{mipself} now has no effect, since the output
1723 is always ELF. @samp{mipslelf} and @samp{mipsbelf} select little- and
1724 big-endian output respectively, but @samp{-EL} and @samp{-EB} are now the
1725 preferred options instead.
1728 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1735 Control how to deal with multiplication overflow and division by zero.
1736 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1737 (and only work for Instruction Set Architecture level 2 and higher);
1738 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1742 When this option is used, @command{@value{AS}} will issue a warning every
1743 time it generates a nop instruction from a macro.
1749 The following options are available when @value{AS} is configured for
1755 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1756 The command-line option @samp{-nojsri2bsr} can be used to disable it.
1760 Enable or disable the silicon filter behaviour. By default this is disabled.
1761 The default can be overridden by the @samp{-sifilter} command-line option.
1764 Alter jump instructions for long displacements.
1766 @item -mcpu=[210|340]
1767 Select the cpu type on the target hardware. This controls which instructions
1771 Assemble for a big endian target.
1774 Assemble for a little endian target.
1783 @xref{LoongArch-Options}, for the options available when @value{AS} is configured
1784 for a LoongArch processor.
1788 @c man begin OPTIONS
1789 The following options are available when @value{AS} is configured for a
1790 LoongArch processor.
1792 @c man begin INCLUDE
1793 @include c-loongarch.texi
1794 @c ended inside the included file
1802 @xref{Meta Options}, for the options available when @value{AS} is configured
1803 for a Meta processor.
1807 @c man begin OPTIONS
1808 The following options are available when @value{AS} is configured for a
1811 @c man begin INCLUDE
1812 @include c-metag.texi
1813 @c ended inside the included file
1818 @c man begin OPTIONS
1820 See the info pages for documentation of the MMIX-specific options.
1826 @xref{NDS32 Options}, for the options available when @value{AS} is configured
1827 for a NDS32 processor.
1829 @c ended inside the included file
1833 @c man begin OPTIONS
1834 The following options are available when @value{AS} is configured for a
1837 @c man begin INCLUDE
1838 @include c-nds32.texi
1839 @c ended inside the included file
1846 @xref{PowerPC-Opts}, for the options available when @value{AS} is configured
1847 for a PowerPC processor.
1851 @c man begin OPTIONS
1852 The following options are available when @value{AS} is configured for a
1855 @c man begin INCLUDE
1857 @c ended inside the included file
1865 @xref{RISC-V-Options}, for the options available when @value{AS} is configured
1866 for a RISC-V processor.
1870 @c man begin OPTIONS
1871 The following options are available when @value{AS} is configured for a
1874 @c man begin INCLUDE
1875 @include c-riscv.texi
1876 @c ended inside the included file
1881 @c man begin OPTIONS
1883 See the info pages for documentation of the RX-specific options.
1887 The following options are available when @value{AS} is configured for the s390
1893 Select the word size, either 31/32 bits or 64 bits.
1896 Select the architecture mode, either the Enterprise System
1897 Architecture (esa) or the z/Architecture mode (zarch).
1898 @item -march=@var{processor}
1899 Specify which s390 processor variant is the target, @samp{g5} (or
1900 @samp{arch3}), @samp{g6}, @samp{z900} (or @samp{arch5}), @samp{z990} (or
1901 @samp{arch6}), @samp{z9-109}, @samp{z9-ec} (or @samp{arch7}), @samp{z10} (or
1902 @samp{arch8}), @samp{z196} (or @samp{arch9}), @samp{zEC12} (or @samp{arch10}),
1903 @samp{z13} (or @samp{arch11}), @samp{z14} (or @samp{arch12}), @samp{z15}
1904 (or @samp{arch13}), or @samp{z16} (or @samp{arch14}).
1906 @itemx -mno-regnames
1907 Allow or disallow symbolic names for registers.
1908 @item -mwarn-areg-zero
1909 Warn whenever the operand for a base or index register has been specified
1910 but evaluates to zero.
1918 @xref{TIC6X Options}, for the options available when @value{AS} is configured
1919 for a TMS320C6000 processor.
1923 @c man begin OPTIONS
1924 The following options are available when @value{AS} is configured for a
1925 TMS320C6000 processor.
1927 @c man begin INCLUDE
1928 @include c-tic6x.texi
1929 @c ended inside the included file
1937 @xref{TILE-Gx Options}, for the options available when @value{AS} is configured
1938 for a TILE-Gx processor.
1942 @c man begin OPTIONS
1943 The following options are available when @value{AS} is configured for a TILE-Gx
1946 @c man begin INCLUDE
1947 @include c-tilegx.texi
1948 @c ended inside the included file
1956 @xref{Visium Options}, for the options available when @value{AS} is configured
1957 for a Visium processor.
1961 @c man begin OPTIONS
1962 The following option is available when @value{AS} is configured for a Visium
1965 @c man begin INCLUDE
1966 @include c-visium.texi
1967 @c ended inside the included file
1975 @xref{Xtensa Options}, for the options available when @value{AS} is configured
1976 for an Xtensa processor.
1980 @c man begin OPTIONS
1981 The following options are available when @value{AS} is configured for an
1984 @c man begin INCLUDE
1985 @include c-xtensa.texi
1986 @c ended inside the included file
1994 @xref{Z80 Options}, for the options available when @value{AS} is configured
1995 for an Z80 processor.
1999 @c man begin OPTIONS
2000 The following options are available when @value{AS} is configured for an
2003 @c man begin INCLUDE
2005 @c ended inside the included file
2011 * Manual:: Structure of this Manual
2012 * GNU Assembler:: The GNU Assembler
2013 * Object Formats:: Object File Formats
2014 * Command Line:: Command Line
2015 * Input Files:: Input Files
2016 * Object:: Output (Object) File
2017 * Errors:: Error and Warning Messages
2021 @section Structure of this Manual
2023 @cindex manual, structure and purpose
2024 This manual is intended to describe what you need to know to use
2025 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
2026 notation for symbols, constants, and expressions; the directives that
2027 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
2030 We also cover special features in the @value{TARGET}
2031 configuration of @command{@value{AS}}, including assembler directives.
2034 This manual also describes some of the machine-dependent features of
2035 various flavors of the assembler.
2038 @cindex machine instructions (not covered)
2039 On the other hand, this manual is @emph{not} intended as an introduction
2040 to programming in assembly language---let alone programming in general!
2041 In a similar vein, we make no attempt to introduce the machine
2042 architecture; we do @emph{not} describe the instruction set, standard
2043 mnemonics, registers or addressing modes that are standard to a
2044 particular architecture.
2046 You may want to consult the manufacturer's
2047 machine architecture manual for this information.
2051 For information on the H8/300 machine instruction set, see @cite{H8/300
2052 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
2053 Programming Manual} (Renesas).
2056 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
2057 see @cite{SH-Microcomputer User's Manual} (Renesas) or
2058 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
2059 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
2062 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
2066 @c I think this is premature---doc@cygnus.com, 17jan1991
2068 Throughout this manual, we assume that you are running @dfn{GNU},
2069 the portable operating system from the @dfn{Free Software
2070 Foundation, Inc.}. This restricts our attention to certain kinds of
2071 computer (in particular, the kinds of computers that @sc{gnu} can run on);
2072 once this assumption is granted examples and definitions need less
2075 @command{@value{AS}} is part of a team of programs that turn a high-level
2076 human-readable series of instructions into a low-level
2077 computer-readable series of instructions. Different versions of
2078 @command{@value{AS}} are used for different kinds of computer.
2081 @c There used to be a section "Terminology" here, which defined
2082 @c "contents", "byte", "word", and "long". Defining "word" to any
2083 @c particular size is confusing when the .word directive may generate 16
2084 @c bits on one machine and 32 bits on another; in general, for the user
2085 @c version of this manual, none of these terms seem essential to define.
2086 @c They were used very little even in the former draft of the manual;
2087 @c this draft makes an effort to avoid them (except in names of
2091 @section The GNU Assembler
2093 @c man begin DESCRIPTION
2095 @sc{gnu} @command{as} is really a family of assemblers.
2097 This manual describes @command{@value{AS}}, a member of that family which is
2098 configured for the @value{TARGET} architectures.
2100 If you use (or have used) the @sc{gnu} assembler on one architecture, you
2101 should find a fairly similar environment when you use it on another
2102 architecture. Each version has much in common with the others,
2103 including object file formats, most assembler directives (often called
2104 @dfn{pseudo-ops}) and assembler syntax.@refill
2106 @cindex purpose of @sc{gnu} assembler
2107 @command{@value{AS}} is primarily intended to assemble the output of the
2108 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
2109 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
2110 assemble correctly everything that other assemblers for the same
2111 machine would assemble.
2113 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
2116 @c This remark should appear in generic version of manual; assumption
2117 @c here is that generic version sets M680x0.
2118 This doesn't mean @command{@value{AS}} always uses the same syntax as another
2119 assembler for the same architecture; for example, we know of several
2120 incompatible versions of 680x0 assembly language syntax.
2125 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
2126 program in one pass of the source file. This has a subtle impact on the
2127 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
2129 @node Object Formats
2130 @section Object File Formats
2132 @cindex object file format
2133 The @sc{gnu} assembler can be configured to produce several alternative
2134 object file formats. For the most part, this does not affect how you
2135 write assembly language programs; but directives for debugging symbols
2136 are typically different in different file formats. @xref{Symbol
2137 Attributes,,Symbol Attributes}.
2140 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
2141 @value{OBJ-NAME} format object files.
2143 @c The following should exhaust all configs that set MULTI-OBJ, ideally
2145 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
2146 SOM or ELF format object files.
2151 @section Command Line
2153 @cindex command line conventions
2155 After the program name @command{@value{AS}}, the command line may contain
2156 options and file names. Options may appear in any order, and may be
2157 before, after, or between file names. The order of file names is
2160 @cindex standard input, as input file
2162 @file{--} (two hyphens) by itself names the standard input file
2163 explicitly, as one of the files for @command{@value{AS}} to assemble.
2165 @cindex options, command line
2166 Except for @samp{--} any command-line argument that begins with a
2167 hyphen (@samp{-}) is an option. Each option changes the behavior of
2168 @command{@value{AS}}. No option changes the way another option works. An
2169 option is a @samp{-} followed by one or more letters; the case of
2170 the letter is important. All options are optional.
2172 Some options expect exactly one file name to follow them. The file
2173 name may either immediately follow the option's letter (compatible
2174 with older assemblers) or it may be the next command argument (@sc{gnu}
2175 standard). These two command lines are equivalent:
2178 @value{AS} -o my-object-file.o mumble.s
2179 @value{AS} -omy-object-file.o mumble.s
2183 @section Input Files
2186 @cindex source program
2187 @cindex files, input
2188 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
2189 describe the program input to one run of @command{@value{AS}}. The program may
2190 be in one or more files; how the source is partitioned into files
2191 doesn't change the meaning of the source.
2193 @c I added "con" prefix to "catenation" just to prove I can overcome my
2194 @c APL training... doc@cygnus.com
2195 The source program is a concatenation of the text in all the files, in the
2198 @c man begin DESCRIPTION
2199 Each time you run @command{@value{AS}} it assembles exactly one source
2200 program. The source program is made up of one or more files.
2201 (The standard input is also a file.)
2203 You give @command{@value{AS}} a command line that has zero or more input file
2204 names. The input files are read (from left file name to right). A
2205 command-line argument (in any position) that has no special meaning
2206 is taken to be an input file name.
2208 If you give @command{@value{AS}} no file names it attempts to read one input file
2209 from the @command{@value{AS}} standard input, which is normally your terminal. You
2210 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
2213 Use @samp{--} if you need to explicitly name the standard input file
2214 in your command line.
2216 If the source is empty, @command{@value{AS}} produces a small, empty object
2221 @subheading Filenames and Line-numbers
2223 @cindex input file linenumbers
2224 @cindex line numbers, in input files
2225 There are two ways of locating a line in the input file (or files) and
2226 either may be used in reporting error messages. One way refers to a line
2227 number in a physical file; the other refers to a line number in a
2228 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
2230 @dfn{Physical files} are those files named in the command line given
2231 to @command{@value{AS}}.
2233 @dfn{Logical files} are simply names declared explicitly by assembler
2234 directives; they bear no relation to physical files. Logical file names help
2235 error messages reflect the original source file, when @command{@value{AS}} source
2236 is itself synthesized from other files. @command{@value{AS}} understands the
2237 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
2238 @ref{File,,@code{.file}}.
2241 @section Output (Object) File
2247 Every time you run @command{@value{AS}} it produces an output file, which is
2248 your assembly language program translated into numbers. This file
2249 is the object file. Its default name is @code{a.out}.
2250 You can give it another name by using the @option{-o} option. Conventionally,
2251 object file names end with @file{.o}. The default name is used for historical
2252 reasons: older assemblers were capable of assembling self-contained programs
2253 directly into a runnable program. (For some formats, this isn't currently
2254 possible, but it can be done for the @code{a.out} format.)
2258 The object file is meant for input to the linker @code{@value{LD}}. It contains
2259 assembled program code, information to help @code{@value{LD}} integrate
2260 the assembled program into a runnable file, and (optionally) symbolic
2261 information for the debugger.
2263 @c link above to some info file(s) like the description of a.out.
2264 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
2267 @section Error and Warning Messages
2269 @c man begin DESCRIPTION
2271 @cindex error messages
2272 @cindex warning messages
2273 @cindex messages from assembler
2274 @command{@value{AS}} may write warnings and error messages to the standard error
2275 file (usually your terminal). This should not happen when a compiler
2276 runs @command{@value{AS}} automatically. Warnings report an assumption made so
2277 that @command{@value{AS}} could keep assembling a flawed program; errors report a
2278 grave problem that stops the assembly.
2282 @cindex format of warning messages
2283 Warning messages have the format
2286 file_name:@b{NNN}:Warning Message Text
2290 @cindex file names and line numbers, in warnings/errors
2291 (where @b{NNN} is a line number). If both a logical file name
2292 (@pxref{File,,@code{.file}}) and a logical line number
2294 (@pxref{Line,,@code{.line}})
2296 have been given then they will be used, otherwise the file name and line number
2297 in the current assembler source file will be used. The message text is
2298 intended to be self explanatory (in the grand Unix tradition).
2300 Note the file name must be set via the logical version of the @code{.file}
2301 directive, not the DWARF2 version of the @code{.file} directive. For example:
2305 error_assembler_source
2311 produces this output:
2315 asm.s:2: Error: no such instruction: `error_assembler_source'
2316 foo.c:31: Error: no such instruction: `error_c_source'
2319 @cindex format of error messages
2320 Error messages have the format
2323 file_name:@b{NNN}:FATAL:Error Message Text
2326 The file name and line number are derived as for warning
2327 messages. The actual message text may be rather less explanatory
2328 because many of them aren't supposed to happen.
2331 @chapter Command-Line Options
2333 @cindex options, all versions of assembler
2334 This chapter describes command-line options available in @emph{all}
2335 versions of the @sc{gnu} assembler; see @ref{Machine Dependencies},
2336 for options specific
2338 to the @value{TARGET} target.
2341 to particular machine architectures.
2344 @c man begin DESCRIPTION
2346 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
2347 you can use the @samp{-Wa} option to pass arguments through to the assembler.
2348 The assembler arguments must be separated from each other (and the @samp{-Wa})
2349 by commas. For example:
2352 gcc -c -g -O -Wa,-alh,-L file.c
2356 This passes two options to the assembler: @samp{-alh} (emit a listing to
2357 standard output with high-level and assembly source) and @samp{-L} (retain
2358 local symbols in the symbol table).
2360 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
2361 command-line options are automatically passed to the assembler by the compiler.
2362 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
2363 precisely what options it passes to each compilation pass, including the
2369 * a:: -a[cdghlns] enable listings
2370 * alternate:: --alternate enable alternate macro syntax
2371 * D:: -D for compatibility
2372 * f:: -f to work faster
2373 * I:: -I for .include search path
2374 @ifclear DIFF-TBL-KLUGE
2375 * K:: -K for compatibility
2377 @ifset DIFF-TBL-KLUGE
2378 * K:: -K for difference tables
2381 * L:: -L to retain local symbols
2382 * listing:: --listing-XXX to configure listing output
2383 * M:: -M or --mri to assemble in MRI compatibility mode
2384 * MD:: --MD for dependency tracking
2385 * no-pad-sections:: --no-pad-sections to stop section padding
2386 * o:: -o to name the object file
2387 * R:: -R to join data and text sections
2388 * statistics:: --statistics to see statistics about assembly
2389 * traditional-format:: --traditional-format for compatible output
2390 * v:: -v to announce version
2391 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
2392 * Z:: -Z to make object file even after errors
2396 @section Enable Listings: @option{-a[cdghlns]}
2406 @cindex listings, enabling
2407 @cindex assembly listings, enabling
2409 These options enable listing output from the assembler. By itself,
2410 @samp{-a} requests high-level, assembly, and symbols listing.
2411 You can use other letters to select specific options for the list:
2412 @samp{-ah} requests a high-level language listing,
2413 @samp{-al} requests an output-program assembly listing, and
2414 @samp{-as} requests a symbol table listing.
2415 High-level listings require that a compiler debugging option like
2416 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
2419 Use the @samp{-ag} option to print a first section with general assembly
2420 information, like @value{AS} version, switches passed, or time stamp.
2422 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
2423 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
2424 other conditional), or a true @code{.if} followed by an @code{.else}, will be
2425 omitted from the listing.
2427 Use the @samp{-ad} option to omit debugging directives from the
2430 Once you have specified one of these options, you can further control
2431 listing output and its appearance using the directives @code{.list},
2432 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
2434 The @samp{-an} option turns off all forms processing.
2435 If you do not request listing output with one of the @samp{-a} options, the
2436 listing-control directives have no effect.
2438 The letters after @samp{-a} may be combined into one option,
2439 @emph{e.g.}, @samp{-aln}.
2441 Note if the assembler source is coming from the standard input (e.g.,
2443 is being created by @code{@value{GCC}} and the @samp{-pipe} command-line switch
2444 is being used) then the listing will not contain any comments or preprocessor
2445 directives. This is because the listing code buffers input source lines from
2446 stdin only after they have been preprocessed by the assembler. This reduces
2447 memory usage and makes the code more efficient.
2450 @section @option{--alternate}
2453 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
2456 @section @option{-D}
2459 This option has no effect whatsoever, but it is accepted to make it more
2460 likely that scripts written for other assemblers also work with
2461 @command{@value{AS}}.
2464 @section Work Faster: @option{-f}
2467 @cindex trusted compiler
2468 @cindex faster processing (@option{-f})
2469 @samp{-f} should only be used when assembling programs written by a
2470 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
2471 and comment preprocessing on
2472 the input file(s) before assembling them. @xref{Preprocessing,
2476 @emph{Warning:} if you use @samp{-f} when the files actually need to be
2477 preprocessed (if they contain comments, for example), @command{@value{AS}} does
2482 @section @code{.include} Search Path: @option{-I} @var{path}
2484 @kindex -I @var{path}
2485 @cindex paths for @code{.include}
2486 @cindex search path for @code{.include}
2487 @cindex @code{include} directive search path
2488 Use this option to add a @var{path} to the list of directories
2489 @command{@value{AS}} searches for files specified in @code{.include}
2490 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
2491 many times as necessary to include a variety of paths. The current
2492 working directory is always searched first; after that, @command{@value{AS}}
2493 searches any @samp{-I} directories in the same order as they were
2494 specified (left to right) on the command line.
2497 @section Difference Tables: @option{-K}
2500 @ifclear DIFF-TBL-KLUGE
2501 On the @value{TARGET} family, this option is allowed, but has no effect. It is
2502 permitted for compatibility with the @sc{gnu} assembler on other platforms,
2503 where it can be used to warn when the assembler alters the machine code
2504 generated for @samp{.word} directives in difference tables. The @value{TARGET}
2505 family does not have the addressing limitations that sometimes lead to this
2506 alteration on other platforms.
2509 @ifset DIFF-TBL-KLUGE
2510 @cindex difference tables, warning
2511 @cindex warning for altered difference tables
2512 @command{@value{AS}} sometimes alters the code emitted for directives of the
2513 form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}.
2514 You can use the @samp{-K} option if you want a warning issued when this
2519 @section Include Local Symbols: @option{-L}
2522 @cindex local symbols, retaining in output
2523 Symbols beginning with system-specific local label prefixes, typically
2524 @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are
2525 called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see
2526 such symbols when debugging, because they are intended for the use of
2527 programs (like compilers) that compose assembler programs, not for your
2528 notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard
2529 such symbols, so you do not normally debug with them.
2531 This option tells @command{@value{AS}} to retain those local symbols
2532 in the object file. Usually if you do this you also tell the linker
2533 @code{@value{LD}} to preserve those symbols.
2536 @section Configuring listing output: @option{--listing}
2538 The listing feature of the assembler can be enabled via the command-line switch
2539 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
2540 hex dump of the corresponding locations in the output object file, and displays
2541 them as a listing file. The format of this listing can be controlled by
2542 directives inside the assembler source (i.e., @code{.list} (@pxref{List}),
2543 @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}),
2544 @code{.psize} (@pxref{Psize}), and
2545 @code{.eject} (@pxref{Eject}) and also by the following switches:
2548 @item --listing-lhs-width=@samp{number}
2549 @kindex --listing-lhs-width
2550 @cindex Width of first line disassembly output
2551 Sets the maximum width, in words, of the first line of the hex byte dump. This
2552 dump appears on the left hand side of the listing output.
2554 @item --listing-lhs-width2=@samp{number}
2555 @kindex --listing-lhs-width2
2556 @cindex Width of continuation lines of disassembly output
2557 Sets the maximum width, in words, of any further lines of the hex byte dump for
2558 a given input source line. If this value is not specified, it defaults to being
2559 the same as the value specified for @samp{--listing-lhs-width}. If neither
2560 switch is used the default is to one.
2562 @item --listing-rhs-width=@samp{number}
2563 @kindex --listing-rhs-width
2564 @cindex Width of source line output
2565 Sets the maximum width, in characters, of the source line that is displayed
2566 alongside the hex dump. The default value for this parameter is 100. The
2567 source line is displayed on the right hand side of the listing output.
2569 @item --listing-cont-lines=@samp{number}
2570 @kindex --listing-cont-lines
2571 @cindex Maximum number of continuation lines
2572 Sets the maximum number of continuation lines of hex dump that will be
2573 displayed for a given single line of source input. The default value is 4.
2577 @section Assemble in MRI Compatibility Mode: @option{-M}
2580 @cindex MRI compatibility mode
2581 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
2582 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
2583 compatible with the @code{ASM68K} assembler from Microtec Research.
2584 The exact nature of the
2585 MRI syntax will not be documented here; see the MRI manuals for more
2586 information. Note in particular that the handling of macros and macro
2587 arguments is somewhat different. The purpose of this option is to permit
2588 assembling existing MRI assembler code using @command{@value{AS}}.
2590 The MRI compatibility is not complete. Certain operations of the MRI assembler
2591 depend upon its object file format, and can not be supported using other object
2592 file formats. Supporting these would require enhancing each object file format
2593 individually. These are:
2596 @item global symbols in common section
2598 The m68k MRI assembler supports common sections which are merged by the linker.
2599 Other object file formats do not support this. @command{@value{AS}} handles
2600 common sections by treating them as a single common symbol. It permits local
2601 symbols to be defined within a common section, but it can not support global
2602 symbols, since it has no way to describe them.
2604 @item complex relocations
2606 The MRI assemblers support relocations against a negated section address, and
2607 relocations which combine the start addresses of two or more sections. These
2608 are not support by other object file formats.
2610 @item @code{END} pseudo-op specifying start address
2612 The MRI @code{END} pseudo-op permits the specification of a start address.
2613 This is not supported by other object file formats. The start address may
2614 instead be specified using the @option{-e} option to the linker, or in a linker
2617 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
2619 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
2620 name to the output file. This is not supported by other object file formats.
2622 @item @code{ORG} pseudo-op
2624 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
2625 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
2626 which changes the location within the current section. Absolute sections are
2627 not supported by other object file formats. The address of a section may be
2628 assigned within a linker script.
2631 There are some other features of the MRI assembler which are not supported by
2632 @command{@value{AS}}, typically either because they are difficult or because they
2633 seem of little consequence. Some of these may be supported in future releases.
2637 @item EBCDIC strings
2639 EBCDIC strings are not supported.
2641 @item packed binary coded decimal
2643 Packed binary coded decimal is not supported. This means that the @code{DC.P}
2644 and @code{DCB.P} pseudo-ops are not supported.
2646 @item @code{FEQU} pseudo-op
2648 The m68k @code{FEQU} pseudo-op is not supported.
2650 @item @code{NOOBJ} pseudo-op
2652 The m68k @code{NOOBJ} pseudo-op is not supported.
2654 @item @code{OPT} branch control options
2656 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
2657 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
2658 relaxes all branches, whether forward or backward, to an appropriate size, so
2659 these options serve no purpose.
2661 @item @code{OPT} list control options
2663 The following m68k @code{OPT} list control options are ignored: @code{C},
2664 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
2665 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
2667 @item other @code{OPT} options
2669 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
2670 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
2672 @item @code{OPT} @code{D} option is default
2674 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
2675 @code{OPT NOD} may be used to turn it off.
2677 @item @code{XREF} pseudo-op.
2679 The m68k @code{XREF} pseudo-op is ignored.
2684 @section Dependency Tracking: @option{--MD}
2687 @cindex dependency tracking
2690 @command{@value{AS}} can generate a dependency file for the file it creates. This
2691 file consists of a single rule suitable for @code{make} describing the
2692 dependencies of the main source file.
2694 The rule is written to the file named in its argument.
2696 This feature is used in the automatic updating of makefiles.
2698 @node no-pad-sections
2699 @section Output Section Padding
2700 @kindex --no-pad-sections
2701 @cindex output section padding
2702 Normally the assembler will pad the end of each output section up to its
2703 alignment boundary. But this can waste space, which can be significant on
2704 memory constrained targets. So the @option{--no-pad-sections} option will
2705 disable this behaviour.
2708 @section Name the Object File: @option{-o}
2711 @cindex naming object file
2712 @cindex object file name
2713 There is always one object file output when you run @command{@value{AS}}. By
2714 default it has the name @file{a.out}.
2715 You use this option (which takes exactly one filename) to give the
2716 object file a different name.
2718 Whatever the object file is called, @command{@value{AS}} overwrites any
2719 existing file of the same name.
2722 @section Join Data and Text Sections: @option{-R}
2725 @cindex data and text sections, joining
2726 @cindex text and data sections, joining
2727 @cindex joining text and data sections
2728 @cindex merging text and data sections
2729 @option{-R} tells @command{@value{AS}} to write the object file as if all
2730 data-section data lives in the text section. This is only done at
2731 the very last moment: your binary data are the same, but data
2732 section parts are relocated differently. The data section part of
2733 your object file is zero bytes long because all its bytes are
2734 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
2736 When you specify @option{-R} it would be possible to generate shorter
2737 address displacements (because we do not have to cross between text and
2738 data section). We refrain from doing this simply for compatibility with
2739 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
2742 When @command{@value{AS}} is configured for COFF or ELF output,
2743 this option is only useful if you use sections named @samp{.text} and
2748 @option{-R} is not supported for any of the HPPA targets. Using
2749 @option{-R} generates a warning from @command{@value{AS}}.
2753 @section Display Assembly Statistics: @option{--statistics}
2755 @kindex --statistics
2756 @cindex statistics, about assembly
2757 @cindex time, total for assembly
2758 @cindex space used, maximum for assembly
2759 Use @samp{--statistics} to display two statistics about the resources used by
2760 @command{@value{AS}}: the maximum amount of space allocated during the assembly
2761 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
2764 @node traditional-format
2765 @section Compatible Output: @option{--traditional-format}
2767 @kindex --traditional-format
2768 For some targets, the output of @command{@value{AS}} is different in some ways
2769 from the output of some existing assembler. This switch requests
2770 @command{@value{AS}} to use the traditional format instead.
2772 For example, it disables the exception frame optimizations which
2773 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
2776 @section Announce Version: @option{-v}
2780 @cindex assembler version
2781 @cindex version of assembler
2782 You can find out what version of as is running by including the
2783 option @samp{-v} (which you can also spell as @samp{-version}) on the
2787 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
2789 @command{@value{AS}} should never give a warning or error message when
2790 assembling compiler output. But programs written by people often
2791 cause @command{@value{AS}} to give a warning that a particular assumption was
2792 made. All such warnings are directed to the standard error file.
2796 @cindex suppressing warnings
2797 @cindex warnings, suppressing
2798 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
2799 This only affects the warning messages: it does not change any particular of
2800 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
2803 @kindex --fatal-warnings
2804 @cindex errors, caused by warnings
2805 @cindex warnings, causing error
2806 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
2807 files that generate warnings to be in error.
2810 @cindex warnings, switching on
2811 You can switch these options off again by specifying @option{--warn}, which
2812 causes warnings to be output as usual.
2815 @section Generate Object File in Spite of Errors: @option{-Z}
2816 @cindex object file, after errors
2817 @cindex errors, continuing after
2818 After an error message, @command{@value{AS}} normally produces no output. If for
2819 some reason you are interested in object file output even after
2820 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
2821 option. If there are any errors, @command{@value{AS}} continues anyways, and
2822 writes an object file after a final warning message of the form @samp{@var{n}
2823 errors, @var{m} warnings, generating bad object file.}
2828 @cindex machine-independent syntax
2829 @cindex syntax, machine-independent
2830 This chapter describes the machine-independent syntax allowed in a
2831 source file. @command{@value{AS}} syntax is similar to what many other
2832 assemblers use; it is inspired by the BSD 4.2
2837 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
2841 * Preprocessing:: Preprocessing
2842 * Whitespace:: Whitespace
2843 * Comments:: Comments
2844 * Symbol Intro:: Symbols
2845 * Statements:: Statements
2846 * Constants:: Constants
2850 @section Preprocessing
2852 @cindex preprocessing
2853 The @command{@value{AS}} internal preprocessor:
2855 @cindex whitespace, removed by preprocessor
2857 adjusts and removes extra whitespace. It leaves one space or tab before
2858 the keywords on a line, and turns any other whitespace on the line into
2861 @cindex comments, removed by preprocessor
2863 removes all comments, replacing them with a single space, or an
2864 appropriate number of newlines.
2866 @cindex constants, converted by preprocessor
2868 converts character constants into the appropriate numeric values.
2871 It does not do macro processing, include file handling, or
2872 anything else you may get from your C compiler's preprocessor. You can
2873 do include file processing with the @code{.include} directive
2874 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2875 to get other ``CPP'' style preprocessing by giving the input file a
2876 @samp{.S} suffix. @url{https://gcc.gnu.org/onlinedocs/gcc/Overall-Options.html#Overall-Options,
2877 See the 'Options Controlling the Kind of Output' section of the GCC manual for
2880 Excess whitespace, comments, and character constants
2881 cannot be used in the portions of the input text that are not
2884 @cindex turning preprocessing on and off
2885 @cindex preprocessing, turning on and off
2888 If the first line of an input file is @code{#NO_APP} or if you use the
2889 @samp{-f} option, whitespace and comments are not removed from the input file.
2890 Within an input file, you can ask for whitespace and comment removal in
2891 specific portions of the file by putting a line that says @code{#APP} before the
2892 text that may contain whitespace or comments, and putting a line that says
2893 @code{#NO_APP} after this text. This feature is mainly intended to support
2894 @code{asm} statements in compilers whose output is otherwise free of comments
2901 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2902 Whitespace is used to separate symbols, and to make programs neater for
2903 people to read. Unless within character constants
2904 (@pxref{Characters,,Character Constants}), any whitespace means the same
2905 as exactly one space.
2911 There are two ways of rendering comments to @command{@value{AS}}. In both
2912 cases the comment is equivalent to one space.
2914 Anything from @samp{/*} through the next @samp{*/} is a comment.
2915 This means you may not nest these comments.
2919 The only way to include a newline ('\n') in a comment
2920 is to use this sort of comment.
2923 /* This sort of comment does not nest. */
2926 @cindex line comment character
2927 Anything from a @dfn{line comment} character up to the next newline is
2928 considered a comment and is ignored. The line comment character is target
2929 specific, and some targets support multiple comment characters. Some targets
2930 also have line comment characters that only work if they are the first
2931 character on a line. Some targets use a sequence of two characters to
2932 introduce a line comment. Some targets can also change their line comment
2933 characters depending upon command-line options that have been used. For more
2934 details see the @emph{Syntax} section in the documentation for individual
2937 If the line comment character is the hash sign (@samp{#}) then it still has the
2938 special ability to enable and disable preprocessing (@pxref{Preprocessing}) and
2939 to specify logical line numbers:
2942 @cindex lines starting with @code{#}
2943 @cindex logical line numbers
2944 To be compatible with past assemblers, lines that begin with @samp{#} have a
2945 special interpretation. Following the @samp{#} should be an absolute
2946 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2947 line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a
2948 new logical file name. The rest of the line, if any, should be whitespace.
2950 If the first non-whitespace characters on the line are not numeric,
2951 the line is ignored. (Just like a comment.)
2954 # This is an ordinary comment.
2955 # 42-6 "new_file_name" # New logical file name
2956 # This is logical line # 36.
2958 This feature is deprecated, and may disappear from future versions
2959 of @command{@value{AS}}.
2964 @cindex characters used in symbols
2965 @ifclear SPECIAL-SYMS
2966 A @dfn{symbol} is one or more characters chosen from the set of all
2967 letters (both upper and lower case), digits and the three characters
2973 A @dfn{symbol} is one or more characters chosen from the set of all
2974 letters (both upper and lower case), digits and the three characters
2975 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2981 On most machines, you can also use @code{$} in symbol names; exceptions
2982 are noted in @ref{Machine Dependencies}.
2984 No symbol may begin with a digit. Case is significant.
2985 There is no length limit; all characters are significant. Multibyte characters
2986 are supported, but note that the setting of the
2987 @option{--multibyte-handling} option might prevent their use. Symbols
2988 are delimited by characters not in that set, or by the beginning of a file
2989 (since the source program must end with a newline, the end of a file is not a
2990 possible symbol delimiter). @xref{Symbols}.
2992 Symbol names may also be enclosed in double quote @code{"} characters. In such
2993 cases any characters are allowed, except for the NUL character. If a double
2994 quote character is to be included in the symbol name it must be preceded by a
2995 backslash @code{\} character.
2996 @cindex length of symbols
3001 @cindex statements, structure of
3002 @cindex line separator character
3003 @cindex statement separator character
3005 A @dfn{statement} ends at a newline character (@samp{\n}) or a
3006 @dfn{line separator character}. The line separator character is target
3007 specific and described in the @emph{Syntax} section of each
3008 target's documentation. Not all targets support a line separator character.
3009 The newline or line separator character is considered to be part of the
3010 preceding statement. Newlines and separators within character constants are an
3011 exception: they do not end statements.
3013 @cindex newline, required at file end
3014 @cindex EOF, newline must precede
3015 It is an error to end any statement with end-of-file: the last
3016 character of any input file should be a newline.@refill
3018 An empty statement is allowed, and may include whitespace. It is ignored.
3020 @cindex instructions and directives
3021 @cindex directives and instructions
3022 @c "key symbol" is not used elsewhere in the document; seems pedantic to
3023 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
3025 A statement begins with zero or more labels, optionally followed by a
3026 key symbol which determines what kind of statement it is. The key
3027 symbol determines the syntax of the rest of the statement. If the
3028 symbol begins with a dot @samp{.} then the statement is an assembler
3029 directive: typically valid for any computer. If the symbol begins with
3030 a letter the statement is an assembly language @dfn{instruction}: it
3031 assembles into a machine language instruction.
3033 Different versions of @command{@value{AS}} for different computers
3034 recognize different instructions. In fact, the same symbol may
3035 represent a different instruction in a different computer's assembly
3039 @cindex @code{:} (label)
3040 @cindex label (@code{:})
3041 A label is a symbol immediately followed by a colon (@code{:}).
3042 Whitespace before a label or after a colon is permitted, but you may not
3043 have whitespace between a label's symbol and its colon. @xref{Labels}.
3046 For HPPA targets, labels need not be immediately followed by a colon, but
3047 the definition of a label must begin in column zero. This also implies that
3048 only one label may be defined on each line.
3052 label: .directive followed by something
3053 another_label: # This is an empty statement.
3054 instruction operand_1, operand_2, @dots{}
3061 A constant is a number, written so that its value is known by
3062 inspection, without knowing any context. Like this:
3065 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
3066 .ascii "Ring the bell\7" # A string constant.
3067 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
3068 .float 0f-314159265358979323846264338327\
3069 95028841971.693993751E-40 # - pi, a flonum.
3074 * Characters:: Character Constants
3075 * Numbers:: Number Constants
3079 @subsection Character Constants
3081 @cindex character constants
3082 @cindex constants, character
3083 There are two kinds of character constants. A @dfn{character} stands
3084 for one character in one byte and its value may be used in
3085 numeric expressions. String constants (properly called string
3086 @emph{literals}) are potentially many bytes and their values may not be
3087 used in arithmetic expressions.
3091 * Chars:: Characters
3095 @subsubsection Strings
3097 @cindex string constants
3098 @cindex constants, string
3099 A @dfn{string} is written between double-quotes. It may contain
3100 double-quotes or null characters. The way to get special characters
3101 into a string is to @dfn{escape} these characters: precede them with
3102 a backslash @samp{\} character. For example @samp{\\} represents
3103 one backslash: the first @code{\} is an escape which tells
3104 @command{@value{AS}} to interpret the second character literally as a backslash
3105 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
3106 escape character). The complete list of escapes follows.
3108 @cindex escape codes, character
3109 @cindex character escape codes
3110 @c NOTE: Cindex entries must not start with a backlash character.
3111 @c NOTE: This confuses the pdf2texi script when it is creating the
3112 @c NOTE: index based upon the first character and so it generates:
3113 @c NOTE: \initial {\\}
3114 @c NOTE: which then results in the error message:
3115 @c NOTE: Argument of \\ has an extra }.
3116 @c NOTE: So in the index entries below a space character has been
3117 @c NOTE: prepended to avoid this problem.
3120 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
3122 @cindex @code{ \b} (backspace character)
3123 @cindex backspace (@code{\b})
3125 Mnemonic for backspace; for ASCII this is octal code 010.
3128 @c Mnemonic for EOText; for ASCII this is octal code 004.
3130 @cindex @code{ \f} (formfeed character)
3131 @cindex formfeed (@code{\f})
3133 Mnemonic for FormFeed; for ASCII this is octal code 014.
3135 @cindex @code{ \n} (newline character)
3136 @cindex newline (@code{\n})
3138 Mnemonic for newline; for ASCII this is octal code 012.
3141 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
3143 @cindex @code{ \r} (carriage return character)
3144 @cindex carriage return (@code{backslash-r})
3146 Mnemonic for carriage-Return; for ASCII this is octal code 015.
3149 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
3150 @c other assemblers.
3152 @cindex @code{ \t} (tab)
3153 @cindex tab (@code{\t})
3155 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
3158 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
3159 @c @item \x @var{digit} @var{digit} @var{digit}
3160 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
3162 @cindex @code{ \@var{ddd}} (octal character code)
3163 @cindex octal character code (@code{\@var{ddd}})
3164 @item \ @var{digit} @var{digit} @var{digit}
3165 An octal character code. The numeric code is 3 octal digits.
3166 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
3167 for example, @code{\008} has the value 010, and @code{\009} the value 011.
3169 @cindex @code{ \@var{xd...}} (hex character code)
3170 @cindex hex character code (@code{\@var{xd...}})
3171 @item \@code{x} @var{hex-digits...}
3172 A hex character code. All trailing hex digits are combined. Either upper or
3173 lower case @code{x} works.
3175 @cindex @code{ \\} (@samp{\} character)
3176 @cindex backslash (@code{\\})
3178 Represents one @samp{\} character.
3181 @c Represents one @samp{'} (accent acute) character.
3182 @c This is needed in single character literals
3183 @c (@xref{Characters,,Character Constants}.) to represent
3186 @cindex @code{ \"} (doublequote character)
3187 @cindex doublequote (@code{\"})
3189 Represents one @samp{"} character. Needed in strings to represent
3190 this character, because an unescaped @samp{"} would end the string.
3192 @item \ @var{anything-else}
3193 Any other character when escaped by @kbd{\} gives a warning, but
3194 assembles as if the @samp{\} was not present. The idea is that if
3195 you used an escape sequence you clearly didn't want the literal
3196 interpretation of the following character. However @command{@value{AS}} has no
3197 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
3198 code and warns you of the fact.
3201 Which characters are escapable, and what those escapes represent,
3202 varies widely among assemblers. The current set is what we think
3203 the BSD 4.2 assembler recognizes, and is a subset of what most C
3204 compilers recognize. If you are in doubt, do not use an escape
3208 @subsubsection Characters
3210 @cindex single character constant
3211 @cindex character, single
3212 @cindex constant, single character
3213 A single character may be written as a single quote immediately followed by
3214 that character. Some backslash escapes apply to characters, @code{\b},
3215 @code{\f}, @code{\n}, @code{\r}, @code{\t}, and @code{\"} with the same meaning
3216 as for strings, plus @code{\'} for a single quote. So if you want to write the
3217 character backslash, you must write @kbd{'\\} where the first @code{\} escapes
3218 the second @code{\}. As you can see, the quote is an acute accent, not a grave
3221 @ifclear abnormal-separator
3222 (or semicolon @samp{;})
3224 @ifset abnormal-separator
3226 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
3231 immediately following an acute accent is taken as a literal character
3232 and does not count as the end of a statement. The value of a character
3233 constant in a numeric expression is the machine's byte-wide code for
3234 that character. @command{@value{AS}} assumes your character code is ASCII:
3235 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
3238 @subsection Number Constants
3240 @cindex constants, number
3241 @cindex number constants
3242 @command{@value{AS}} distinguishes three kinds of numbers according to how they
3243 are stored in the target machine. @emph{Integers} are numbers that
3244 would fit into an @code{int} in the C language. @emph{Bignums} are
3245 integers, but they are stored in more than 32 bits. @emph{Flonums}
3246 are floating point numbers, described below.
3249 * Integers:: Integers
3257 @subsubsection Integers
3259 @cindex constants, integer
3261 @cindex binary integers
3262 @cindex integers, binary
3263 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
3264 the binary digits @samp{01}.
3266 @cindex octal integers
3267 @cindex integers, octal
3268 An octal integer is @samp{0} followed by zero or more of the octal
3269 digits (@samp{01234567}).
3271 @cindex decimal integers
3272 @cindex integers, decimal
3273 A decimal integer starts with a non-zero digit followed by zero or
3274 more digits (@samp{0123456789}).
3276 @cindex hexadecimal integers
3277 @cindex integers, hexadecimal
3278 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
3279 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
3281 Integers have the usual values. To denote a negative integer, use
3282 the prefix operator @samp{-} discussed under expressions
3283 (@pxref{Prefix Ops,,Prefix Operators}).
3286 @subsubsection Bignums
3289 @cindex constants, bignum
3290 A @dfn{bignum} has the same syntax and semantics as an integer
3291 except that the number (or its negative) takes more than 32 bits to
3292 represent in binary. The distinction is made because in some places
3293 integers are permitted while bignums are not.
3296 @subsubsection Flonums
3298 @cindex floating point numbers
3299 @cindex constants, floating point
3301 @cindex precision, floating point
3302 A @dfn{flonum} represents a floating point number. The translation is
3303 indirect: a decimal floating point number from the text is converted by
3304 @command{@value{AS}} to a generic binary floating point number of more than
3305 sufficient precision. This generic floating point number is converted
3306 to a particular computer's floating point format (or formats) by a
3307 portion of @command{@value{AS}} specialized to that computer.
3309 A flonum is written by writing (in order)
3314 (@samp{0} is optional on the HPPA.)
3318 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
3320 @kbd{e} is recommended. Case is not important.
3322 @c FIXME: verify if flonum syntax really this vague for most cases
3323 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
3324 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
3327 On the H8/300 and Renesas / SuperH SH architectures, the letter must be
3328 one of the letters @samp{DFPRSX} (in upper or lower case).
3330 On the ARC, the letter must be one of the letters @samp{DFRS}
3331 (in upper or lower case).
3333 On the HPPA architecture, the letter must be @samp{E} (upper case only).
3337 One of the letters @samp{DFRS} (in upper or lower case).
3340 One of the letters @samp{DFPRSX} (in upper or lower case).
3343 The letter @samp{E} (upper case only).
3348 An optional sign: either @samp{+} or @samp{-}.
3351 An optional @dfn{integer part}: zero or more decimal digits.
3354 An optional @dfn{fractional part}: @samp{.} followed by zero
3355 or more decimal digits.
3358 An optional exponent, consisting of:
3362 An @samp{E} or @samp{e}.
3363 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
3364 @c principle this can perfectly well be different on different targets.
3366 Optional sign: either @samp{+} or @samp{-}.
3368 One or more decimal digits.
3373 At least one of the integer part or the fractional part must be
3374 present. The floating point number has the usual base-10 value.
3376 @command{@value{AS}} does all processing using integers. Flonums are computed
3377 independently of any floating point hardware in the computer running
3378 @command{@value{AS}}.
3381 @chapter Sections and Relocation
3386 * Secs Background:: Background
3387 * Ld Sections:: Linker Sections
3388 * As Sections:: Assembler Internal Sections
3389 * Sub-Sections:: Sub-Sections
3393 @node Secs Background
3396 Roughly, a section is a range of addresses, with no gaps; all data
3397 ``in'' those addresses is treated the same for some particular purpose.
3398 For example there may be a ``read only'' section.
3400 @cindex linker, and assembler
3401 @cindex assembler, and linker
3402 The linker @code{@value{LD}} reads many object files (partial programs) and
3403 combines their contents to form a runnable program. When @command{@value{AS}}
3404 emits an object file, the partial program is assumed to start at address 0.
3405 @code{@value{LD}} assigns the final addresses for the partial program, so that
3406 different partial programs do not overlap. This is actually an
3407 oversimplification, but it suffices to explain how @command{@value{AS}} uses
3410 @code{@value{LD}} moves blocks of bytes of your program to their run-time
3411 addresses. These blocks slide to their run-time addresses as rigid
3412 units; their length does not change and neither does the order of bytes
3413 within them. Such a rigid unit is called a @emph{section}. Assigning
3414 run-time addresses to sections is called @dfn{relocation}. It includes
3415 the task of adjusting mentions of object-file addresses so they refer to
3416 the proper run-time addresses.
3418 For the H8/300, and for the Renesas / SuperH SH,
3419 @command{@value{AS}} pads sections if needed to
3420 ensure they end on a word (sixteen bit) boundary.
3423 @cindex standard assembler sections
3424 An object file written by @command{@value{AS}} has at least three sections, any
3425 of which may be empty. These are named @dfn{text}, @dfn{data} and
3430 When it generates COFF or ELF output,
3432 @command{@value{AS}} can also generate whatever other named sections you specify
3433 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
3434 If you do not use any directives that place output in the @samp{.text}
3435 or @samp{.data} sections, these sections still exist, but are empty.
3440 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
3442 @command{@value{AS}} can also generate whatever other named sections you
3443 specify using the @samp{.space} and @samp{.subspace} directives. See
3444 @cite{HP9000 Series 800 Assembly Language Reference Manual}
3445 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
3446 assembler directives.
3449 Additionally, @command{@value{AS}} uses different names for the standard
3450 text, data, and bss sections when generating SOM output. Program text
3451 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
3452 BSS into @samp{$BSS$}.
3456 Within the object file, the text section starts at address @code{0}, the
3457 data section follows, and the bss section follows the data section.
3460 When generating either SOM or ELF output files on the HPPA, the text
3461 section starts at address @code{0}, the data section at address
3462 @code{0x4000000}, and the bss section follows the data section.
3465 To let @code{@value{LD}} know which data changes when the sections are
3466 relocated, and how to change that data, @command{@value{AS}} also writes to the
3467 object file details of the relocation needed. To perform relocation
3468 @code{@value{LD}} must know, each time an address in the object
3472 Where in the object file is the beginning of this reference to
3475 How long (in bytes) is this reference?
3477 Which section does the address refer to? What is the numeric value of
3479 (@var{address}) @minus{} (@var{start-address of section})?
3482 Is the reference to an address ``Program-Counter relative''?
3485 @cindex addresses, format of
3486 @cindex section-relative addressing
3487 In fact, every address @command{@value{AS}} ever uses is expressed as
3489 (@var{section}) + (@var{offset into section})
3492 Further, most expressions @command{@value{AS}} computes have this section-relative
3495 (For some object formats, such as SOM for the HPPA, some expressions are
3496 symbol-relative instead.)
3499 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
3500 @var{N} into section @var{secname}.''
3502 Apart from text, data and bss sections you need to know about the
3503 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
3504 addresses in the absolute section remain unchanged. For example, address
3505 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
3506 @code{@value{LD}}. Although the linker never arranges two partial programs'
3507 data sections with overlapping addresses after linking, @emph{by definition}
3508 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
3509 part of a program is always the same address when the program is running as
3510 address @code{@{absolute@ 239@}} in any other part of the program.
3512 The idea of sections is extended to the @dfn{undefined} section. Any
3513 address whose section is unknown at assembly time is by definition
3514 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
3515 Since numbers are always defined, the only way to generate an undefined
3516 address is to mention an undefined symbol. A reference to a named
3517 common block would be such a symbol: its value is unknown at assembly
3518 time so it has section @emph{undefined}.
3520 By analogy the word @emph{section} is used to describe groups of sections in
3521 the linked program. @code{@value{LD}} puts all partial programs' text
3522 sections in contiguous addresses in the linked program. It is
3523 customary to refer to the @emph{text section} of a program, meaning all
3524 the addresses of all partial programs' text sections. Likewise for
3525 data and bss sections.
3527 Some sections are manipulated by @code{@value{LD}}; others are invented for
3528 use of @command{@value{AS}} and have no meaning except during assembly.
3531 @section Linker Sections
3532 @code{@value{LD}} deals with just four kinds of sections, summarized below.
3537 @cindex named sections
3538 @cindex sections, named
3539 @item named sections
3542 @cindex text section
3543 @cindex data section
3547 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
3548 separate but equal sections. Anything you can say of one section is
3551 When the program is running, however, it is
3552 customary for the text section to be unalterable. The
3553 text section is often shared among processes: it contains
3554 instructions, constants and the like. The data section of a running
3555 program is usually alterable: for example, C variables would be stored
3556 in the data section.
3561 This section contains zeroed bytes when your program begins running. It
3562 is used to hold uninitialized variables or common storage. The length of
3563 each partial program's bss section is important, but because it starts
3564 out containing zeroed bytes there is no need to store explicit zero
3565 bytes in the object file. The bss section was invented to eliminate
3566 those explicit zeros from object files.
3568 @cindex absolute section
3569 @item absolute section
3570 Address 0 of this section is always ``relocated'' to runtime address 0.
3571 This is useful if you want to refer to an address that @code{@value{LD}} must
3572 not change when relocating. In this sense we speak of absolute
3573 addresses being ``unrelocatable'': they do not change during relocation.
3575 @cindex undefined section
3576 @item undefined section
3577 This ``section'' is a catch-all for address references to objects not in
3578 the preceding sections.
3579 @c FIXME: ref to some other doc on obj-file formats could go here.
3582 @cindex relocation example
3583 An idealized example of three relocatable sections follows.
3585 The example uses the traditional section names @samp{.text} and @samp{.data}.
3587 Memory addresses are on the horizontal axis.
3591 @c END TEXI2ROFF-KILL
3594 partial program # 1: |ttttt|dddd|00|
3601 partial program # 2: |TTT|DDD|000|
3604 +--+---+-----+--+----+---+-----+~~
3605 linked program: | |TTT|ttttt| |dddd|DDD|00000|
3606 +--+---+-----+--+----+---+-----+~~
3608 addresses: 0 @dots{}
3615 \line{\it Partial program \#1: \hfil}
3616 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3617 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
3619 \line{\it Partial program \#2: \hfil}
3620 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3621 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
3623 \line{\it linked program: \hfil}
3624 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
3625 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
3626 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
3627 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
3629 \line{\it addresses: \hfil}
3633 @c END TEXI2ROFF-KILL
3636 @section Assembler Internal Sections
3638 @cindex internal assembler sections
3639 @cindex sections in messages, internal
3640 These sections are meant only for the internal use of @command{@value{AS}}. They
3641 have no meaning at run-time. You do not really need to know about these
3642 sections for most purposes; but they can be mentioned in @command{@value{AS}}
3643 warning messages, so it might be helpful to have an idea of their
3644 meanings to @command{@value{AS}}. These sections are used to permit the
3645 value of every expression in your assembly language program to be a
3646 section-relative address.
3649 @cindex assembler internal logic error
3650 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
3651 An internal assembler logic error has been found. This means there is a
3652 bug in the assembler.
3654 @cindex expr (internal section)
3656 The assembler stores complex expressions internally as combinations of
3657 symbols. When it needs to represent an expression as a symbol, it puts
3658 it in the expr section.
3660 @c FIXME item transfer[t] vector preload
3661 @c FIXME item transfer[t] vector postload
3662 @c FIXME item register
3666 @section Sub-Sections
3668 @cindex numbered subsections
3669 @cindex grouping data
3675 fall into two sections: text and data.
3677 You may have separate groups of
3679 data in named sections
3683 data in named sections
3689 that you want to end up near to each other in the object file, even though they
3690 are not contiguous in the assembler source. @command{@value{AS}} allows you to
3691 use @dfn{subsections} for this purpose. Within each section, there can be
3692 numbered subsections with values from 0 to 8192. Objects assembled into the
3693 same subsection go into the object file together with other objects in the same
3694 subsection. For example, a compiler might want to store constants in the text
3695 section, but might not want to have them interspersed with the program being
3696 assembled. In this case, the compiler could issue a @samp{.text 0} before each
3697 section of code being output, and a @samp{.text 1} before each group of
3698 constants being output.
3700 Subsections are optional. If you do not use subsections, everything
3701 goes in subsection number zero.
3704 Each subsection is zero-padded up to a multiple of four bytes.
3705 (Subsections may be padded a different amount on different flavors
3706 of @command{@value{AS}}.)
3710 On the H8/300 platform, each subsection is zero-padded to a word
3711 boundary (two bytes).
3712 The same is true on the Renesas SH.
3716 Subsections appear in your object file in numeric order, lowest numbered
3717 to highest. (All this to be compatible with other people's assemblers.)
3718 The object file contains no representation of subsections; @code{@value{LD}} and
3719 other programs that manipulate object files see no trace of them.
3720 They just see all your text subsections as a text section, and all your
3721 data subsections as a data section.
3723 To specify which subsection you want subsequent statements assembled
3724 into, use a numeric argument to specify it, in a @samp{.text
3725 @var{expression}} or a @samp{.data @var{expression}} statement.
3728 When generating COFF output, you
3733 can also use an extra subsection
3734 argument with arbitrary named sections: @samp{.section @var{name},
3739 When generating ELF output, you
3744 can also use the @code{.subsection} directive (@pxref{SubSection})
3745 to specify a subsection: @samp{.subsection @var{expression}}.
3747 @var{Expression} should be an absolute expression
3748 (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0}
3749 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3750 begins in @code{text 0}. For instance:
3752 .text 0 # The default subsection is text 0 anyway.
3753 .ascii "This lives in the first text subsection. *"
3755 .ascii "But this lives in the second text subsection."
3757 .ascii "This lives in the data section,"
3758 .ascii "in the first data subsection."
3760 .ascii "This lives in the first text section,"
3761 .ascii "immediately following the asterisk (*)."
3764 Each section has a @dfn{location counter} incremented by one for every byte
3765 assembled into that section. Because subsections are merely a convenience
3766 restricted to @command{@value{AS}} there is no concept of a subsection location
3767 counter. There is no way to directly manipulate a location counter---but the
3768 @code{.align} directive changes it, and any label definition captures its
3769 current value. The location counter of the section where statements are being
3770 assembled is said to be the @dfn{active} location counter.
3773 @section bss Section
3776 @cindex common variable storage
3777 The bss section is used for local common variable storage.
3778 You may allocate address space in the bss section, but you may
3779 not dictate data to load into it before your program executes. When
3780 your program starts running, all the contents of the bss
3781 section are zeroed bytes.
3783 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3784 @ref{Lcomm,,@code{.lcomm}}.
3786 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3787 another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}.
3790 When assembling for a target which supports multiple sections, such as ELF or
3791 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3792 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3793 section. Typically the section will only contain symbol definitions and
3794 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3801 Symbols are a central concept: the programmer uses symbols to name
3802 things, the linker uses symbols to link, and the debugger uses symbols
3806 @cindex debuggers, and symbol order
3807 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3808 the same order they were declared. This may break some debuggers.
3813 * Setting Symbols:: Giving Symbols Other Values
3814 * Symbol Names:: Symbol Names
3815 * Dot:: The Special Dot Symbol
3816 * Symbol Attributes:: Symbol Attributes
3823 A @dfn{label} is written as a symbol immediately followed by a colon
3824 @samp{:}. The symbol then represents the current value of the
3825 active location counter, and is, for example, a suitable instruction
3826 operand. You are warned if you use the same symbol to represent two
3827 different locations: the first definition overrides any other
3831 On the HPPA, the usual form for a label need not be immediately followed by a
3832 colon, but instead must start in column zero. Only one label may be defined on
3833 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3834 provides a special directive @code{.label} for defining labels more flexibly.
3837 @node Setting Symbols
3838 @section Giving Symbols Other Values
3840 @cindex assigning values to symbols
3841 @cindex symbol values, assigning
3842 A symbol can be given an arbitrary value by writing a symbol, followed
3843 by an equals sign @samp{=}, followed by an expression
3844 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3845 directive. @xref{Set,,@code{.set}}. In the same way, using a double
3846 equals sign @samp{=}@samp{=} here represents an equivalent of the
3847 @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}.
3850 Blackfin does not support symbol assignment with @samp{=}.
3854 @section Symbol Names
3856 @cindex symbol names
3857 @cindex names, symbol
3858 @ifclear SPECIAL-SYMS
3859 Symbol names begin with a letter or with one of @samp{._}. On most
3860 machines, you can also use @code{$} in symbol names; exceptions are
3861 noted in @ref{Machine Dependencies}. That character may be followed by any
3862 string of digits, letters, dollar signs (unless otherwise noted for a
3863 particular target machine), and underscores. These restrictions do not
3864 apply when quoting symbol names by @samp{"}, which is permitted for most
3865 targets. Escaping characters in quoted symbol names with @samp{\} generally
3866 extends only to @samp{\} itself and @samp{"}, at the time of writing.
3870 Symbol names begin with a letter or with one of @samp{._}. On the
3871 Renesas SH you can also use @code{$} in symbol names. That
3872 character may be followed by any string of digits, letters, dollar signs (save
3873 on the H8/300), and underscores.
3877 Case of letters is significant: @code{foo} is a different symbol name
3880 Symbol names do not start with a digit. An exception to this rule is made for
3881 Local Labels. See below.
3883 Multibyte characters are supported, but note that the setting of the
3884 @option{multibyte-handling} option might prevent their use.
3885 To generate a symbol name containing
3886 multibyte characters enclose it within double quotes and use escape codes. cf
3887 @xref{Strings}. Generating a multibyte symbol name from a label is not
3888 currently supported.
3890 Since multibyte symbol names are unusual, and could possibly be used
3891 maliciously, @command{@value{AS}} provides a command line option
3892 (@option{--multibyte-handling=warn-sym-only}) which can be used to generate a
3893 warning message whenever a symbol name containing multibyte characters is defined.
3895 Each symbol has exactly one name. Each name in an assembly language program
3896 refers to exactly one symbol. You may use that symbol name any number of times
3899 @subheading Local Symbol Names
3901 @cindex local symbol names
3902 @cindex symbol names, local
3903 A local symbol is any symbol beginning with certain local label prefixes.
3904 By default, the local label prefix is @samp{.L} for ELF systems or
3905 @samp{L} for traditional a.out systems, but each target may have its own
3906 set of local label prefixes.
3908 On the HPPA local symbols begin with @samp{L$}.
3911 Local symbols are defined and used within the assembler, but they are
3912 normally not saved in object files. Thus, they are not visible when debugging.
3913 You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols})
3914 to retain the local symbols in the object files.
3916 @subheading Local Labels
3918 @cindex local labels
3919 @cindex temporary symbol names
3920 @cindex symbol names, temporary
3921 Local labels are different from local symbols. Local labels help compilers and
3922 programmers use names temporarily. They create symbols which are guaranteed to
3923 be unique over the entire scope of the input source code and which can be
3924 referred to by a simple notation. To define a local label, write a label of
3925 the form @samp{@b{N}:} (where @b{N} represents any non-negative integer).
3926 To refer to the most recent previous definition of that label write
3927 @samp{@b{N}b}, using the same number as when you defined the label. To refer
3928 to the next definition of a local label, write @samp{@b{N}f}. The @samp{b}
3929 stands for ``backwards'' and the @samp{f} stands for ``forwards''.
3931 There is no restriction on how you can use these labels, and you can reuse them
3932 too. So that it is possible to repeatedly define the same local label (using
3933 the same number @samp{@b{N}}), although you can only refer to the most recently
3934 defined local label of that number (for a backwards reference) or the next
3935 definition of a specific local label for a forward reference. It is also worth
3936 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3937 implemented in a slightly more efficient manner than the others.
3948 Which is the equivalent of:
3951 label_1: branch label_3
3952 label_2: branch label_1
3953 label_3: branch label_4
3954 label_4: branch label_3
3957 Local label names are only a notational device. They are immediately
3958 transformed into more conventional symbol names before the assembler uses them.
3959 The symbol names are stored in the symbol table, appear in error messages, and
3960 are optionally emitted to the object file. The names are constructed using
3964 @item @emph{local label prefix}
3965 All local symbols begin with the system-specific local label prefix.
3966 Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols
3967 that start with the local label prefix. These labels are
3968 used for symbols you are never intended to see. If you use the
3969 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3970 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3971 you may use them in debugging.
3974 This is the number that was used in the local label definition. So if the
3975 label is written @samp{55:} then the number is @samp{55}.
3978 This unusual character is included so you do not accidentally invent a symbol
3979 of the same name. The character has ASCII value of @samp{\002} (control-B).
3981 @item @emph{ordinal number}
3982 This is a serial number to keep the labels distinct. The first definition of
3983 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3984 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3985 the number @samp{1} and its 15th definition gets @samp{15} as well.
3988 So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and
3989 the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}.
3991 @subheading Dollar Local Labels
3992 @cindex dollar local symbols
3994 On some targets @code{@value{AS}} also supports an even more local form of
3995 local labels called dollar labels. These labels go out of scope (i.e., they
3996 become undefined) as soon as a non-local label is defined. Thus they remain
3997 valid for only a small region of the input source code. Normal local labels,
3998 by contrast, remain in scope for the entire file, or until they are redefined
3999 by another occurrence of the same local label.
4001 Dollar labels are defined in exactly the same way as ordinary local labels,
4002 except that they have a dollar sign suffix to their numeric value, e.g.,
4005 They can also be distinguished from ordinary local labels by their transformed
4006 names which use ASCII character @samp{\001} (control-A) as the magic character
4007 to distinguish them from ordinary labels. For example, the fifth definition of
4008 @samp{6$} may be named @samp{.L6@kbd{C-A}5}.
4011 @section The Special Dot Symbol
4013 @cindex dot (symbol)
4014 @cindex @code{.} (symbol)
4015 @cindex current address
4016 @cindex location counter
4017 The special symbol @samp{.} refers to the current address that
4018 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
4019 .long .} defines @code{melvin} to contain its own address.
4020 Assigning a value to @code{.} is treated the same as a @code{.org}
4022 @ifclear no-space-dir
4023 Thus, the expression @samp{.=.+4} is the same as saying
4027 @node Symbol Attributes
4028 @section Symbol Attributes
4030 @cindex symbol attributes
4031 @cindex attributes, symbol
4032 Every symbol has, as well as its name, the attributes ``Value'' and
4033 ``Type''. Depending on output format, symbols can also have auxiliary
4036 The detailed definitions are in @file{a.out.h}.
4039 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
4040 all these attributes, and probably won't warn you. This makes the
4041 symbol an externally defined symbol, which is generally what you
4045 * Symbol Value:: Value
4046 * Symbol Type:: Type
4048 * a.out Symbols:: Symbol Attributes: @code{a.out}
4051 * COFF Symbols:: Symbol Attributes for COFF
4054 * SOM Symbols:: Symbol Attributes for SOM
4061 @cindex value of a symbol
4062 @cindex symbol value
4063 The value of a symbol is (usually) 32 bits. For a symbol which labels a
4064 location in the text, data, bss or absolute sections the value is the
4065 number of addresses from the start of that section to the label.
4066 Naturally for text, data and bss sections the value of a symbol changes
4067 as @code{@value{LD}} changes section base addresses during linking. Absolute
4068 symbols' values do not change during linking: that is why they are
4071 The value of an undefined symbol is treated in a special way. If it is
4072 0 then the symbol is not defined in this assembler source file, and
4073 @code{@value{LD}} tries to determine its value from other files linked into the
4074 same program. You make this kind of symbol simply by mentioning a symbol
4075 name without defining it. A non-zero value represents a @code{.comm}
4076 common declaration. The value is how much common storage to reserve, in
4077 bytes (addresses). The symbol refers to the first address of the
4083 @cindex type of a symbol
4085 The type attribute of a symbol contains relocation (section)
4086 information, any flag settings indicating that a symbol is external, and
4087 (optionally), other information for linkers and debuggers. The exact
4088 format depends on the object-code output format in use.
4092 @subsection Symbol Attributes: @code{a.out}
4094 @cindex @code{a.out} symbol attributes
4095 @cindex symbol attributes, @code{a.out}
4098 * Symbol Desc:: Descriptor
4099 * Symbol Other:: Other
4103 @subsubsection Descriptor
4105 @cindex descriptor, of @code{a.out} symbol
4106 This is an arbitrary 16-bit value. You may establish a symbol's
4107 descriptor value by using a @code{.desc} statement
4108 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
4109 @command{@value{AS}}.
4112 @subsubsection Other
4114 @cindex other attribute, of @code{a.out} symbol
4115 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
4120 @subsection Symbol Attributes for COFF
4122 @cindex COFF symbol attributes
4123 @cindex symbol attributes, COFF
4125 The COFF format supports a multitude of auxiliary symbol attributes;
4126 like the primary symbol attributes, they are set between @code{.def} and
4127 @code{.endef} directives.
4129 @subsubsection Primary Attributes
4131 @cindex primary attributes, COFF symbols
4132 The symbol name is set with @code{.def}; the value and type,
4133 respectively, with @code{.val} and @code{.type}.
4135 @subsubsection Auxiliary Attributes
4137 @cindex auxiliary attributes, COFF symbols
4138 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
4139 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
4140 table information for COFF.
4145 @subsection Symbol Attributes for SOM
4147 @cindex SOM symbol attributes
4148 @cindex symbol attributes, SOM
4150 The SOM format for the HPPA supports a multitude of symbol attributes set with
4151 the @code{.EXPORT} and @code{.IMPORT} directives.
4153 The attributes are described in @cite{HP9000 Series 800 Assembly
4154 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
4155 @code{EXPORT} assembler directive documentation.
4159 @chapter Expressions
4163 @cindex numeric values
4164 An @dfn{expression} specifies an address or numeric value.
4165 Whitespace may precede and/or follow an expression.
4167 The result of an expression must be an absolute number, or else an offset into
4168 a particular section. If an expression is not absolute, and there is not
4169 enough information when @command{@value{AS}} sees the expression to know its
4170 section, a second pass over the source program might be necessary to interpret
4171 the expression---but the second pass is currently not implemented.
4172 @command{@value{AS}} aborts with an error message in this situation.
4175 * Empty Exprs:: Empty Expressions
4176 * Integer Exprs:: Integer Expressions
4180 @section Empty Expressions
4182 @cindex empty expressions
4183 @cindex expressions, empty
4184 An empty expression has no value: it is just whitespace or null.
4185 Wherever an absolute expression is required, you may omit the
4186 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
4187 is compatible with other assemblers.
4190 @section Integer Expressions
4192 @cindex integer expressions
4193 @cindex expressions, integer
4194 An @dfn{integer expression} is one or more @emph{arguments} delimited
4195 by @emph{operators}.
4198 * Arguments:: Arguments
4199 * Operators:: Operators
4200 * Prefix Ops:: Prefix Operators
4201 * Infix Ops:: Infix Operators
4205 @subsection Arguments
4207 @cindex expression arguments
4208 @cindex arguments in expressions
4209 @cindex operands in expressions
4210 @cindex arithmetic operands
4211 @dfn{Arguments} are symbols, numbers or subexpressions. In other
4212 contexts arguments are sometimes called ``arithmetic operands''. In
4213 this manual, to avoid confusing them with the ``instruction operands'' of
4214 the machine language, we use the term ``argument'' to refer to parts of
4215 expressions only, reserving the word ``operand'' to refer only to machine
4216 instruction operands.
4218 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
4219 @var{section} is one of text, data, bss, absolute,
4220 or undefined. @var{NNN} is a signed, 2's complement 32 bit
4223 Numbers are usually integers.
4225 A number can be a flonum or bignum. In this case, you are warned
4226 that only the low order 32 bits are used, and @command{@value{AS}} pretends
4227 these 32 bits are an integer. You may write integer-manipulating
4228 instructions that act on exotic constants, compatible with other
4231 @cindex subexpressions
4232 Subexpressions are a left parenthesis @samp{(} followed by an integer
4233 expression, followed by a right parenthesis @samp{)}; or a prefix
4234 operator followed by an argument.
4237 @subsection Operators
4239 @cindex operators, in expressions
4240 @cindex arithmetic functions
4241 @cindex functions, in expressions
4242 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
4243 operators are followed by an argument. Infix operators appear
4244 between their arguments. Operators may be preceded and/or followed by
4248 @subsection Prefix Operator
4250 @cindex prefix operators
4251 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
4252 one argument, which must be absolute.
4254 @c the tex/end tex stuff surrounding this small table is meant to make
4255 @c it align, on the printed page, with the similar table in the next
4256 @c section (which is inside an enumerate).
4258 \global\advance\leftskip by \itemindent
4263 @dfn{Negation}. Two's complement negation.
4265 @dfn{Complementation}. Bitwise not.
4269 \global\advance\leftskip by -\itemindent
4273 @subsection Infix Operators
4275 @cindex infix operators
4276 @cindex operators, permitted arguments
4277 @dfn{Infix operators} take two arguments, one on either side. Operators
4278 have precedence, but operations with equal precedence are performed left
4279 to right. Apart from @code{+} or @option{-}, both arguments must be
4280 absolute, and the result is absolute.
4283 @cindex operator precedence
4284 @cindex precedence of operators
4291 @dfn{Multiplication}.
4294 @dfn{Division}. Truncation is the same as the C operator @samp{/}
4300 @dfn{Shift Left}. Same as the C operator @samp{<<}.
4303 @dfn{Shift Right}. Same as the C operator @samp{>>}.
4307 Intermediate precedence
4312 @dfn{Bitwise Inclusive Or}.
4318 @dfn{Bitwise Exclusive Or}.
4321 @dfn{Bitwise Or Not}.
4328 @cindex addition, permitted arguments
4329 @cindex plus, permitted arguments
4330 @cindex arguments for addition
4332 @dfn{Addition}. If either argument is absolute, the result has the section of
4333 the other argument. You may not add together arguments from different
4336 @cindex subtraction, permitted arguments
4337 @cindex minus, permitted arguments
4338 @cindex arguments for subtraction
4340 @dfn{Subtraction}. If the right argument is absolute, the
4341 result has the section of the left argument.
4342 If both arguments are in the same section, the result is absolute.
4343 You may not subtract arguments from different sections.
4344 @c FIXME is there still something useful to say about undefined - undefined ?
4346 @cindex comparison expressions
4347 @cindex expressions, comparison
4352 @dfn{Is Not Equal To}
4356 @dfn{Is Greater Than}
4358 @dfn{Is Greater Than Or Equal To}
4360 @dfn{Is Less Than Or Equal To}
4362 The comparison operators can be used as infix operators. A true result has a
4363 value of -1 whereas a false result has a value of 0. Note, these operators
4364 perform signed comparisons.
4367 @item Lowest Precedence
4376 These two logical operations can be used to combine the results of sub
4377 expressions. Note, unlike the comparison operators a true result returns a
4378 value of 1 but a false result does still return 0. Also note that the logical
4379 or operator has a slightly lower precedence than logical and.
4384 In short, it's only meaningful to add or subtract the @emph{offsets} in an
4385 address; you can only have a defined section in one of the two arguments.
4388 @chapter Assembler Directives
4390 @cindex directives, machine independent
4391 @cindex pseudo-ops, machine independent
4392 @cindex machine independent directives
4393 All assembler directives have names that begin with a period (@samp{.}).
4394 The names are case insensitive for most targets, and usually written
4397 This chapter discusses directives that are available regardless of the
4398 target machine configuration for the @sc{gnu} assembler.
4400 Some machine configurations provide additional directives.
4401 @xref{Machine Dependencies}.
4404 @ifset machine-directives
4405 @xref{Machine Dependencies}, for additional directives.
4410 * Abort:: @code{.abort}
4412 * ABORT (COFF):: @code{.ABORT}
4415 * Align:: @code{.align [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
4416 * Altmacro:: @code{.altmacro}
4417 * Ascii:: @code{.ascii "@var{string}"}@dots{}
4418 * Asciz:: @code{.asciz "@var{string}"}@dots{}
4419 * Attach_to_group:: @code{.attach_to_group @var{name}}
4420 * Balign:: @code{.balign [@var{abs-expr}[, @var{abs-expr}]]}
4421 * Bss:: @code{.bss @var{subsection}}
4422 * Bundle directives:: @code{.bundle_align_mode @var{abs-expr}}, etc
4423 * Byte:: @code{.byte @var{expressions}}
4424 * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
4425 * Comm:: @code{.comm @var{symbol} , @var{length} }
4426 * Data:: @code{.data @var{subsection}}
4427 * Dc:: @code{.dc[@var{size}] @var{expressions}}
4428 * Dcb:: @code{.dcb[@var{size}] @var{number} [,@var{fill}]}
4429 * Ds:: @code{.ds[@var{size}] @var{number} [,@var{fill}]}
4431 * Def:: @code{.def @var{name}}
4434 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
4440 * Double:: @code{.double @var{flonums}}
4441 * Eject:: @code{.eject}
4442 * Else:: @code{.else}
4443 * Elseif:: @code{.elseif}
4446 * Endef:: @code{.endef}
4449 * Endfunc:: @code{.endfunc}
4450 * Endif:: @code{.endif}
4451 * Equ:: @code{.equ @var{symbol}, @var{expression}}
4452 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
4453 * Eqv:: @code{.eqv @var{symbol}, @var{expression}}
4455 * Error:: @code{.error @var{string}}
4456 * Exitm:: @code{.exitm}
4457 * Extern:: @code{.extern}
4458 * Fail:: @code{.fail}
4459 * File:: @code{.file}
4460 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
4461 * Float:: @code{.float @var{flonums}}
4462 * Func:: @code{.func}
4463 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4465 * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
4466 * Hidden:: @code{.hidden @var{names}}
4469 * hword:: @code{.hword @var{expressions}}
4470 * Ident:: @code{.ident}
4471 * If:: @code{.if @var{absolute expression}}
4472 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4473 * Include:: @code{.include "@var{file}"}
4474 * Int:: @code{.int @var{expressions}}
4476 * Internal:: @code{.internal @var{names}}
4479 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
4480 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
4481 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
4482 * Lflags:: @code{.lflags}
4483 @ifclear no-line-dir
4484 * Line:: @code{.line @var{line-number}}
4487 * Linkonce:: @code{.linkonce [@var{type}]}
4488 * List:: @code{.list}
4489 * Ln:: @code{.ln @var{line-number}}
4490 * Loc:: @code{.loc @var{fileno} @var{lineno}}
4491 * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}}
4493 * Local:: @code{.local @var{names}}
4496 * Long:: @code{.long @var{expressions}}
4498 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
4501 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
4502 * MRI:: @code{.mri @var{val}}
4503 * Noaltmacro:: @code{.noaltmacro}
4504 * Nolist:: @code{.nolist}
4506 * Nops:: @code{.nops @var{size}[, @var{control}]}
4507 * Octa:: @code{.octa @var{bignums}}
4508 * Offset:: @code{.offset @var{loc}}
4509 * Org:: @code{.org @var{new-lc}, @var{fill}}
4510 * P2align:: @code{.p2align [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
4512 * PopSection:: @code{.popsection}
4513 * Previous:: @code{.previous}
4516 * Print:: @code{.print @var{string}}
4518 * Protected:: @code{.protected @var{names}}
4521 * Psize:: @code{.psize @var{lines}, @var{columns}}
4522 * Purgem:: @code{.purgem @var{name}}
4524 * PushSection:: @code{.pushsection @var{name}}
4527 * Quad:: @code{.quad @var{bignums}}
4528 * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
4529 * Rept:: @code{.rept @var{count}}
4530 * Sbttl:: @code{.sbttl "@var{subheading}"}
4532 * Scl:: @code{.scl @var{class}}
4535 * Section:: @code{.section @var{name}[, @var{flags}]}
4538 * Set:: @code{.set @var{symbol}, @var{expression}}
4539 * Short:: @code{.short @var{expressions}}
4540 * Single:: @code{.single @var{flonums}}
4542 * Size:: @code{.size [@var{name} , @var{expression}]}
4544 @ifclear no-space-dir
4545 * Skip:: @code{.skip @var{size} [,@var{fill}]}
4548 * Sleb128:: @code{.sleb128 @var{expressions}}
4549 @ifclear no-space-dir
4550 * Space:: @code{.space @var{size} [,@var{fill}]}
4553 * Stab:: @code{.stabd, .stabn, .stabs}
4556 * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
4557 * Struct:: @code{.struct @var{expression}}
4559 * SubSection:: @code{.subsection}
4560 * Symver:: @code{.symver @var{name},@var{name2@@nodename}[,@var{visibility}]}
4564 * Tag:: @code{.tag @var{structname}}
4567 * Text:: @code{.text @var{subsection}}
4568 * Title:: @code{.title "@var{heading}"}
4570 * Tls_common:: @code{.tls_common @var{symbol}, @var{length}[, @var{alignment}]}
4573 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
4576 * Uleb128:: @code{.uleb128 @var{expressions}}
4578 * Val:: @code{.val @var{addr}}
4582 * Version:: @code{.version "@var{string}"}
4583 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
4584 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
4587 * Warning:: @code{.warning @var{string}}
4588 * Weak:: @code{.weak @var{names}}
4589 * Weakref:: @code{.weakref @var{alias}, @var{symbol}}
4590 * Word:: @code{.word @var{expressions}}
4591 @ifclear no-space-dir
4592 * Zero:: @code{.zero @var{size}}
4594 * 2byte:: @code{.2byte @var{expressions}}
4595 * 4byte:: @code{.4byte @var{expressions}}
4596 * 8byte:: @code{.8byte @var{bignums}}
4597 * Deprecated:: Deprecated Directives
4601 @section @code{.abort}
4603 @cindex @code{abort} directive
4604 @cindex stopping the assembly
4605 This directive stops the assembly immediately. It is for
4606 compatibility with other assemblers. The original idea was that the
4607 assembly language source would be piped into the assembler. If the sender
4608 of the source quit, it could use this directive tells @command{@value{AS}} to
4609 quit also. One day @code{.abort} will not be supported.
4613 @section @code{.ABORT} (COFF)
4615 @cindex @code{ABORT} directive
4616 When producing COFF output, @command{@value{AS}} accepts this directive as a
4617 synonym for @samp{.abort}.
4622 @section @code{.align [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
4624 @cindex padding the location counter
4625 @cindex @code{align} directive
4626 Pad the location counter (in the current subsection) to a particular storage
4627 boundary. The first expression (which must be absolute) is the alignment
4628 required, as described below. If this expression is omitted then a default
4629 value of 0 is used, effectively disabling alignment requirements.
4631 The second expression (also absolute) gives the fill value to be stored in the
4632 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4633 padding bytes are normally zero. However, on most systems, if the section is
4634 marked as containing code and the fill value is omitted, the space is filled
4635 with no-op instructions.
4637 The third expression is also absolute, and is also optional. If it is present,
4638 it is the maximum number of bytes that should be skipped by this alignment
4639 directive. If doing the alignment would require skipping more bytes than the
4640 specified maximum, then the alignment is not done at all. You can omit the
4641 fill value (the second argument) entirely by simply using two commas after the
4642 required alignment; this can be useful if you want the alignment to be filled
4643 with no-op instructions when appropriate.
4645 The way the required alignment is specified varies from system to system.
4646 For the arc, hppa, i386 using ELF, iq2000, m68k, or1k,
4647 s390, sparc, tic4x and xtensa, the first expression is the
4648 alignment request in bytes. For example @samp{.align 8} advances
4649 the location counter until it is a multiple of 8. If the location counter
4650 is already a multiple of 8, no change is needed. For the tic54x, the
4651 first expression is the alignment request in words.
4653 For other systems, including ppc, i386 using a.out format, arm and
4654 strongarm, it is the
4655 number of low-order zero bits the location counter must have after
4656 advancement. For example @samp{.align 3} advances the location
4657 counter until it is a multiple of 8. If the location counter is already a
4658 multiple of 8, no change is needed.
4660 This inconsistency is due to the different behaviors of the various
4661 native assemblers for these systems which GAS must emulate.
4662 GAS also provides @code{.balign} and @code{.p2align} directives,
4663 described later, which have a consistent behavior across all
4664 architectures (but are specific to GAS).
4667 @section @code{.altmacro}
4668 Enable alternate macro mode, enabling:
4671 @item LOCAL @var{name} [ , @dots{} ]
4672 One additional directive, @code{LOCAL}, is available. It is used to
4673 generate a string replacement for each of the @var{name} arguments, and
4674 replace any instances of @var{name} in each macro expansion. The
4675 replacement string is unique in the assembly, and different for each
4676 separate macro expansion. @code{LOCAL} allows you to write macros that
4677 define symbols, without fear of conflict between separate macro expansions.
4679 @item String delimiters
4680 You can write strings delimited in these other ways besides
4681 @code{"@var{string}"}:
4684 @item '@var{string}'
4685 You can delimit strings with single-quote characters.
4687 @item <@var{string}>
4688 You can delimit strings with matching angle brackets.
4691 @item single-character string escape
4692 To include any single character literally in a string (even if the
4693 character would otherwise have some special meaning), you can prefix the
4694 character with @samp{!} (an exclamation mark). For example, you can
4695 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4697 @item Expression results as strings
4698 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4699 and use the result as a string.
4703 @section @code{.ascii "@var{string}"}@dots{}
4705 @cindex @code{ascii} directive
4706 @cindex string literals
4707 @code{.ascii} expects zero or more string literals (@pxref{Strings})
4708 separated by commas. It assembles each string (with no automatic
4709 trailing zero byte) into consecutive addresses.
4712 @section @code{.asciz "@var{string}"}@dots{}
4714 @cindex @code{asciz} directive
4715 @cindex zero-terminated strings
4716 @cindex null-terminated strings
4717 @code{.asciz} is just like @code{.ascii}, but each string is followed by
4718 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''. Note that
4719 multiple string arguments not separated by commas will be concatenated
4720 together and only one final zero byte will be stored.
4722 @node Attach_to_group
4723 @section @code{.attach_to_group @var{name}}
4724 Attaches the current section to the named group. This is like declaring
4725 the section with the @code{G} attribute, but can be done after the section
4726 has been created. Note if the group section does not exist at the point that
4727 this directive is used then it will be created.
4730 @section @code{.balign[wl] [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
4732 @cindex padding the location counter given number of bytes
4733 @cindex @code{balign} directive
4734 Pad the location counter (in the current subsection) to a particular
4735 storage boundary. The first expression (which must be absolute) is the
4736 alignment request in bytes. For example @samp{.balign 8} advances
4737 the location counter until it is a multiple of 8. If the location counter
4738 is already a multiple of 8, no change is needed. If the expression is omitted
4739 then a default value of 0 is used, effectively disabling alignment requirements.
4741 The second expression (also absolute) gives the fill value to be stored in the
4742 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4743 padding bytes are normally zero. However, on most systems, if the section is
4744 marked as containing code and the fill value is omitted, the space is filled
4745 with no-op instructions.
4747 The third expression is also absolute, and is also optional. If it is present,
4748 it is the maximum number of bytes that should be skipped by this alignment
4749 directive. If doing the alignment would require skipping more bytes than the
4750 specified maximum, then the alignment is not done at all. You can omit the
4751 fill value (the second argument) entirely by simply using two commas after the
4752 required alignment; this can be useful if you want the alignment to be filled
4753 with no-op instructions when appropriate.
4755 @cindex @code{balignw} directive
4756 @cindex @code{balignl} directive
4757 The @code{.balignw} and @code{.balignl} directives are variants of the
4758 @code{.balign} directive. The @code{.balignw} directive treats the fill
4759 pattern as a two byte word value. The @code{.balignl} directives treats the
4760 fill pattern as a four byte longword value. For example, @code{.balignw
4761 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4762 filled in with the value 0x368d (the exact placement of the bytes depends upon
4763 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4767 @section @code{.bss @var{subsection}}
4768 @cindex @code{bss} directive
4770 @code{.bss} tells @command{@value{AS}} to assemble the following statements
4771 onto the end of the bss section.
4773 For ELF based targets an optional @var{subsection} expression (which must
4774 evaluate to a positive integer) can be provided. In this case the statements
4775 are appended to the end of the indicated bss subsection.
4778 @node Bundle directives
4779 @section Bundle directives
4780 @subsection @code{.bundle_align_mode @var{abs-expr}}
4781 @cindex @code{bundle_align_mode} directive
4783 @cindex instruction bundle
4784 @cindex aligned instruction bundle
4785 @code{.bundle_align_mode} enables or disables @dfn{aligned instruction
4786 bundle} mode. In this mode, sequences of adjacent instructions are grouped
4787 into fixed-sized @dfn{bundles}. If the argument is zero, this mode is
4788 disabled (which is the default state). If the argument it not zero, it
4789 gives the size of an instruction bundle as a power of two (as for the
4790 @code{.p2align} directive, @pxref{P2align}).
4792 For some targets, it's an ABI requirement that no instruction may span a
4793 certain aligned boundary. A @dfn{bundle} is simply a sequence of
4794 instructions that starts on an aligned boundary. For example, if
4795 @var{abs-expr} is @code{5} then the bundle size is 32, so each aligned
4796 chunk of 32 bytes is a bundle. When aligned instruction bundle mode is in
4797 effect, no single instruction may span a boundary between bundles. If an
4798 instruction would start too close to the end of a bundle for the length of
4799 that particular instruction to fit within the bundle, then the space at the
4800 end of that bundle is filled with no-op instructions so the instruction
4801 starts in the next bundle. As a corollary, it's an error if any single
4802 instruction's encoding is longer than the bundle size.
4804 @subsection @code{.bundle_lock} and @code{.bundle_unlock}
4805 @cindex @code{bundle_lock} directive
4806 @cindex @code{bundle_unlock} directive
4807 The @code{.bundle_lock} and directive @code{.bundle_unlock} directives
4808 allow explicit control over instruction bundle padding. These directives
4809 are only valid when @code{.bundle_align_mode} has been used to enable
4810 aligned instruction bundle mode. It's an error if they appear when
4811 @code{.bundle_align_mode} has not been used at all, or when the last
4812 directive was @w{@code{.bundle_align_mode 0}}.
4814 @cindex bundle-locked
4815 For some targets, it's an ABI requirement that certain instructions may
4816 appear only as part of specified permissible sequences of multiple
4817 instructions, all within the same bundle. A pair of @code{.bundle_lock}
4818 and @code{.bundle_unlock} directives define a @dfn{bundle-locked}
4819 instruction sequence. For purposes of aligned instruction bundle mode, a
4820 sequence starting with @code{.bundle_lock} and ending with
4821 @code{.bundle_unlock} is treated as a single instruction. That is, the
4822 entire sequence must fit into a single bundle and may not span a bundle
4823 boundary. If necessary, no-op instructions will be inserted before the
4824 first instruction of the sequence so that the whole sequence starts on an
4825 aligned bundle boundary. It's an error if the sequence is longer than the
4828 For convenience when using @code{.bundle_lock} and @code{.bundle_unlock}
4829 inside assembler macros (@pxref{Macro}), bundle-locked sequences may be
4830 nested. That is, a second @code{.bundle_lock} directive before the next
4831 @code{.bundle_unlock} directive has no effect except that it must be
4832 matched by another closing @code{.bundle_unlock} so that there is the
4833 same number of @code{.bundle_lock} and @code{.bundle_unlock} directives.
4836 @section @code{.byte @var{expressions}}
4838 @cindex @code{byte} directive
4839 @cindex integers, one byte
4840 @code{.byte} expects zero or more expressions, separated by commas.
4841 Each expression is assembled into the next byte.
4843 @node CFI directives
4844 @section CFI directives
4845 @subsection @code{.cfi_sections @var{section_list}}
4846 @cindex @code{cfi_sections} directive
4847 @code{.cfi_sections} may be used to specify whether CFI directives
4848 should emit @code{.eh_frame} section and/or @code{.debug_frame} section.
4849 If @var{section_list} is @code{.eh_frame}, @code{.eh_frame} is emitted,
4850 if @var{section_list} is @code{.debug_frame}, @code{.debug_frame} is emitted.
4851 To emit both use @code{.eh_frame, .debug_frame}. The default if this
4852 directive is not used is @code{.cfi_sections .eh_frame}.
4854 On targets that support compact unwinding tables these can be generated
4855 by specifying @code{.eh_frame_entry} instead of @code{.eh_frame}.
4857 Some targets may support an additional name, such as @code{.c6xabi.exidx}
4858 which is used by the @value{TIC6X} target.
4860 The @code{.cfi_sections} directive can be repeated, with the same or different
4861 arguments, provided that CFI generation has not yet started. Once CFI
4862 generation has started however the section list is fixed and any attempts to
4863 redefine it will result in an error.
4865 @subsection @code{.cfi_startproc [simple]}
4866 @cindex @code{cfi_startproc} directive
4867 @code{.cfi_startproc} is used at the beginning of each function that
4868 should have an entry in @code{.eh_frame}. It initializes some internal
4869 data structures. Don't forget to close the function by
4870 @code{.cfi_endproc}.
4872 Unless @code{.cfi_startproc} is used along with parameter @code{simple}
4873 it also emits some architecture dependent initial CFI instructions.
4875 @subsection @code{.cfi_endproc}
4876 @cindex @code{cfi_endproc} directive
4877 @code{.cfi_endproc} is used at the end of a function where it closes its
4878 unwind entry previously opened by
4879 @code{.cfi_startproc}, and emits it to @code{.eh_frame}.
4881 @subsection @code{.cfi_personality @var{encoding} [, @var{exp}]}
4882 @cindex @code{cfi_personality} directive
4883 @code{.cfi_personality} defines personality routine and its encoding.
4884 @var{encoding} must be a constant determining how the personality
4885 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4886 argument is not present, otherwise second argument should be
4887 a constant or a symbol name. When using indirect encodings,
4888 the symbol provided should be the location where personality
4889 can be loaded from, not the personality routine itself.
4890 The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff},
4891 no personality routine.
4893 @subsection @code{.cfi_personality_id @var{id}}
4894 @cindex @code{cfi_personality_id} directive
4895 @code{cfi_personality_id} defines a personality routine by its index as
4896 defined in a compact unwinding format.
4897 Only valid when generating compact EH frames (i.e.
4898 with @code{.cfi_sections eh_frame_entry}.
4900 @subsection @code{.cfi_fde_data [@var{opcode1} [, @dots{}]]}
4901 @cindex @code{cfi_fde_data} directive
4902 @code{cfi_fde_data} is used to describe the compact unwind opcodes to be
4903 used for the current function. These are emitted inline in the
4904 @code{.eh_frame_entry} section if small enough and there is no LSDA, or
4905 in the @code{.gnu.extab} section otherwise.
4906 Only valid when generating compact EH frames (i.e.
4907 with @code{.cfi_sections eh_frame_entry}.
4909 @subsection @code{.cfi_lsda @var{encoding} [, @var{exp}]}
4910 @code{.cfi_lsda} defines LSDA and its encoding.
4911 @var{encoding} must be a constant determining how the LSDA
4912 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), the second
4913 argument is not present, otherwise the second argument should be a constant
4914 or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff},
4915 meaning that no LSDA is present.
4917 @subsection @code{.cfi_inline_lsda} [@var{align}]
4918 @code{.cfi_inline_lsda} marks the start of a LSDA data section and
4919 switches to the corresponding @code{.gnu.extab} section.
4920 Must be preceded by a CFI block containing a @code{.cfi_lsda} directive.
4921 Only valid when generating compact EH frames (i.e.
4922 with @code{.cfi_sections eh_frame_entry}.
4924 The table header and unwinding opcodes will be generated at this point,
4925 so that they are immediately followed by the LSDA data. The symbol
4926 referenced by the @code{.cfi_lsda} directive should still be defined
4927 in case a fallback FDE based encoding is used. The LSDA data is terminated
4928 by a section directive.
4930 The optional @var{align} argument specifies the alignment required.
4931 The alignment is specified as a power of two, as with the
4932 @code{.p2align} directive.
4934 @subsection @code{.cfi_def_cfa @var{register}, @var{offset}}
4935 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4936 address from @var{register} and add @var{offset} to it}.
4938 @subsection @code{.cfi_def_cfa_register @var{register}}
4939 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4940 now on @var{register} will be used instead of the old one. Offset
4943 @subsection @code{.cfi_def_cfa_offset @var{offset}}
4944 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4945 remains the same, but @var{offset} is new. Note that it is the
4946 absolute offset that will be added to a defined register to compute
4949 @subsection @code{.cfi_adjust_cfa_offset @var{offset}}
4950 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4951 value that is added/subtracted from the previous offset.
4953 @subsection @code{.cfi_offset @var{register}, @var{offset}}
4954 Previous value of @var{register} is saved at offset @var{offset} from
4957 @subsection @code{.cfi_val_offset @var{register}, @var{offset}}
4958 Previous value of @var{register} is CFA + @var{offset}.
4960 @subsection @code{.cfi_rel_offset @var{register}, @var{offset}}
4961 Previous value of @var{register} is saved at offset @var{offset} from
4962 the current CFA register. This is transformed to @code{.cfi_offset}
4963 using the known displacement of the CFA register from the CFA.
4964 This is often easier to use, because the number will match the
4965 code it's annotating.
4967 @subsection @code{.cfi_register @var{register1}, @var{register2}}
4968 Previous value of @var{register1} is saved in register @var{register2}.
4970 @subsection @code{.cfi_restore @var{register}}
4971 @code{.cfi_restore} says that the rule for @var{register} is now the
4972 same as it was at the beginning of the function, after all initial
4973 instruction added by @code{.cfi_startproc} were executed.
4975 @subsection @code{.cfi_undefined @var{register}}
4976 From now on the previous value of @var{register} can't be restored anymore.
4978 @subsection @code{.cfi_same_value @var{register}}
4979 Current value of @var{register} is the same like in the previous frame,
4980 i.e. no restoration needed.
4982 @subsection @code{.cfi_remember_state} and @code{.cfi_restore_state}
4983 @code{.cfi_remember_state} pushes the set of rules for every register onto an
4984 implicit stack, while @code{.cfi_restore_state} pops them off the stack and
4985 places them in the current row. This is useful for situations where you have
4986 multiple @code{.cfi_*} directives that need to be undone due to the control
4987 flow of the program. For example, we could have something like this (assuming
4988 the CFA is the value of @code{rbp}):
4998 .cfi_def_cfa %rsp, 8
5001 /* Do something else */
5004 Here, we want the @code{.cfi} directives to affect only the rows corresponding
5005 to the instructions before @code{label}. This means we'd have to add multiple
5006 @code{.cfi} directives after @code{label} to recreate the original save
5007 locations of the registers, as well as setting the CFA back to the value of
5008 @code{rbp}. This would be clumsy, and result in a larger binary size. Instead,
5020 .cfi_def_cfa %rsp, 8
5024 /* Do something else */
5027 That way, the rules for the instructions after @code{label} will be the same
5028 as before the first @code{.cfi_restore} without having to use multiple
5029 @code{.cfi} directives.
5031 @subsection @code{.cfi_return_column @var{register}}
5032 Change return column @var{register}, i.e. the return address is either
5033 directly in @var{register} or can be accessed by rules for @var{register}.
5035 @subsection @code{.cfi_signal_frame}
5036 Mark current function as signal trampoline.
5038 @subsection @code{.cfi_window_save}
5039 SPARC register window has been saved.
5041 @subsection @code{.cfi_escape} @var{expression}[, @dots{}]
5042 Allows the user to add arbitrary bytes to the unwind info. One
5043 might use this to add OS-specific CFI opcodes, or generic CFI
5044 opcodes that GAS does not yet support.
5046 @subsection @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}}
5047 The current value of @var{register} is @var{label}. The value of @var{label}
5048 will be encoded in the output file according to @var{encoding}; see the
5049 description of @code{.cfi_personality} for details on this encoding.
5051 The usefulness of equating a register to a fixed label is probably
5052 limited to the return address register. Here, it can be useful to
5053 mark a code segment that has only one return address which is reached
5054 by a direct branch and no copy of the return address exists in memory
5055 or another register.
5058 @section @code{.comm @var{symbol} , @var{length} }
5060 @cindex @code{comm} directive
5061 @cindex symbol, common
5062 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
5063 common symbol in one object file may be merged with a defined or common symbol
5064 of the same name in another object file. If @code{@value{LD}} does not see a
5065 definition for the symbol--just one or more common symbols--then it will
5066 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
5067 absolute expression. If @code{@value{LD}} sees multiple common symbols with
5068 the same name, and they do not all have the same size, it will allocate space
5069 using the largest size.
5072 When using ELF or (as a GNU extension) PE, the @code{.comm} directive takes
5073 an optional third argument. This is the desired alignment of the symbol,
5074 specified for ELF as a byte boundary (for example, an alignment of 16 means
5075 that the least significant 4 bits of the address should be zero), and for PE
5076 as a power of two (for example, an alignment of 5 means aligned to a 32-byte
5077 boundary). The alignment must be an absolute expression, and it must be a
5078 power of two. If @code{@value{LD}} allocates uninitialized memory for the
5079 common symbol, it will use the alignment when placing the symbol. If no
5080 alignment is specified, @command{@value{AS}} will set the alignment to the
5081 largest power of two less than or equal to the size of the symbol, up to a
5082 maximum of 16 on ELF, or the default section alignment of 4 on PE@footnote{This
5083 is not the same as the executable image file alignment controlled by @code{@value{LD}}'s
5084 @samp{--section-alignment} option; image file sections in PE are aligned to
5085 multiples of 4096, which is far too large an alignment for ordinary variables.
5086 It is rather the default alignment for (non-debug) sections within object
5087 (@samp{*.o}) files, which are less strictly aligned.}.
5091 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
5092 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
5096 @section @code{.data @var{subsection}}
5097 @cindex @code{data} directive
5099 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
5100 end of the data subsection numbered @var{subsection} (which is an
5101 absolute expression). If @var{subsection} is omitted, it defaults
5105 @section @code{.dc[@var{size}] @var{expressions}}
5106 @cindex @code{dc} directive
5108 The @code{.dc} directive expects zero or more @var{expressions} separated by
5109 commas. These expressions are evaluated and their values inserted into the
5110 current section. The size of the emitted value depends upon the suffix to the
5111 @code{.dc} directive:
5115 Emits N-bit values, where N is the size of an address on the target system.
5119 Emits double precision floating-point values.
5121 Emits 32-bit values.
5123 Emits single precision floating-point values.
5125 Emits 16-bit values.
5126 Note - this is true even on targets where the @code{.word} directive would emit
5129 Emits long double precision floating-point values.
5132 If no suffix is used then @samp{.w} is assumed.
5134 The byte ordering is target dependent, as is the size and format of floating
5138 @section @code{.dcb[@var{size}] @var{number} [,@var{fill}]}
5139 @cindex @code{dcb} directive
5140 This directive emits @var{number} copies of @var{fill}, each of @var{size}
5141 bytes. Both @var{number} and @var{fill} are absolute expressions. If the
5142 comma and @var{fill} are omitted, @var{fill} is assumed to be zero. The
5143 @var{size} suffix, if present, must be one of:
5147 Emits single byte values.
5149 Emits double-precision floating point values.
5151 Emits 4-byte values.
5153 Emits single-precision floating point values.
5155 Emits 2-byte values.
5157 Emits long double-precision floating point values.
5160 If the @var{size} suffix is omitted then @samp{.w} is assumed.
5162 The byte ordering is target dependent, as is the size and format of floating
5166 @section @code{.ds[@var{size}] @var{number} [,@var{fill}]}
5167 @cindex @code{ds} directive
5168 This directive emits @var{number} copies of @var{fill}, each of @var{size}
5169 bytes. Both @var{number} and @var{fill} are absolute expressions. If the
5170 comma and @var{fill} are omitted, @var{fill} is assumed to be zero. The
5171 @var{size} suffix, if present, must be one of:
5175 Emits single byte values.
5177 Emits 8-byte values.
5179 Emits 4-byte values.
5181 Emits values with size matching packed-decimal floating-point ones.
5183 Emits 4-byte values.
5185 Emits 2-byte values.
5187 Emits values with size matching long double precision floating-point ones.
5190 Note - unlike the @code{.dcb} directive the @samp{.d}, @samp{.s} and @samp{.x}
5191 suffixes do not indicate that floating-point values are to be inserted.
5193 If the @var{size} suffix is omitted then @samp{.w} is assumed.
5195 The byte ordering is target dependent.
5200 @section @code{.def @var{name}}
5202 @cindex @code{def} directive
5203 @cindex COFF symbols, debugging
5204 @cindex debugging COFF symbols
5205 Begin defining debugging information for a symbol @var{name}; the
5206 definition extends until the @code{.endef} directive is encountered.
5211 @section @code{.desc @var{symbol}, @var{abs-expression}}
5213 @cindex @code{desc} directive
5214 @cindex COFF symbol descriptor
5215 @cindex symbol descriptor, COFF
5216 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
5217 to the low 16 bits of an absolute expression.
5220 The @samp{.desc} directive is not available when @command{@value{AS}} is
5221 configured for COFF output; it is only for @code{a.out} or @code{b.out}
5222 object format. For the sake of compatibility, @command{@value{AS}} accepts
5223 it, but produces no output, when configured for COFF.
5229 @section @code{.dim}
5231 @cindex @code{dim} directive
5232 @cindex COFF auxiliary symbol information
5233 @cindex auxiliary symbol information, COFF
5234 This directive is generated by compilers to include auxiliary debugging
5235 information in the symbol table. It is only permitted inside
5236 @code{.def}/@code{.endef} pairs.
5240 @section @code{.double @var{flonums}}
5242 @cindex @code{double} directive
5243 @cindex floating point numbers (double)
5244 @code{.double} expects zero or more flonums, separated by commas. It
5245 assembles floating point numbers.
5247 The exact kind of floating point numbers emitted depends on how
5248 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5252 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
5253 in @sc{ieee} format.
5258 @section @code{.eject}
5260 @cindex @code{eject} directive
5261 @cindex new page, in listings
5262 @cindex page, in listings
5263 @cindex listing control: new page
5264 Force a page break at this point, when generating assembly listings.
5267 @section @code{.else}
5269 @cindex @code{else} directive
5270 @code{.else} is part of the @command{@value{AS}} support for conditional
5271 assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section
5272 of code to be assembled if the condition for the preceding @code{.if}
5276 @section @code{.elseif}
5278 @cindex @code{elseif} directive
5279 @code{.elseif} is part of the @command{@value{AS}} support for conditional
5280 assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new
5281 @code{.if} block that would otherwise fill the entire @code{.else} section.
5284 @section @code{.end}
5286 @cindex @code{end} directive
5287 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
5288 process anything in the file past the @code{.end} directive.
5292 @section @code{.endef}
5294 @cindex @code{endef} directive
5295 This directive flags the end of a symbol definition begun with
5300 @section @code{.endfunc}
5301 @cindex @code{endfunc} directive
5302 @code{.endfunc} marks the end of a function specified with @code{.func}.
5305 @section @code{.endif}
5307 @cindex @code{endif} directive
5308 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
5309 it marks the end of a block of code that is only assembled
5310 conditionally. @xref{If,,@code{.if}}.
5313 @section @code{.equ @var{symbol}, @var{expression}}
5315 @cindex @code{equ} directive
5316 @cindex assigning values to symbols
5317 @cindex symbols, assigning values to
5318 This directive sets the value of @var{symbol} to @var{expression}.
5319 It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}.
5322 The syntax for @code{equ} on the HPPA is
5323 @samp{@var{symbol} .equ @var{expression}}.
5327 The syntax for @code{equ} on the Z80 is
5328 @samp{@var{symbol} equ @var{expression}}.
5329 On the Z80 it is an error if @var{symbol} is already defined,
5330 but the symbol is not protected from later redefinition.
5331 Compare @ref{Equiv}.
5335 @section @code{.equiv @var{symbol}, @var{expression}}
5336 @cindex @code{equiv} directive
5337 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
5338 the assembler will signal an error if @var{symbol} is already defined. Note a
5339 symbol which has been referenced but not actually defined is considered to be
5342 Except for the contents of the error message, this is roughly equivalent to
5349 plus it protects the symbol from later redefinition.
5352 @section @code{.eqv @var{symbol}, @var{expression}}
5353 @cindex @code{eqv} directive
5354 The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to
5355 evaluate the expression or any part of it immediately. Instead each time
5356 the resulting symbol is used in an expression, a snapshot of its current
5360 @section @code{.err}
5361 @cindex @code{err} directive
5362 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
5363 message and, unless the @option{-Z} option was used, it will not generate an
5364 object file. This can be used to signal an error in conditionally compiled code.
5367 @section @code{.error "@var{string}"}
5368 @cindex error directive
5370 Similarly to @code{.err}, this directive emits an error, but you can specify a
5371 string that will be emitted as the error message. If you don't specify the
5372 message, it defaults to @code{".error directive invoked in source file"}.
5373 @xref{Errors, ,Error and Warning Messages}.
5376 .error "This code has not been assembled and tested."
5380 @section @code{.exitm}
5381 Exit early from the current macro definition. @xref{Macro}.
5384 @section @code{.extern}
5386 @cindex @code{extern} directive
5387 @code{.extern} is accepted in the source program---for compatibility
5388 with other assemblers---but it is ignored. @command{@value{AS}} treats
5389 all undefined symbols as external.
5392 @section @code{.fail @var{expression}}
5394 @cindex @code{fail} directive
5395 Generates an error or a warning. If the value of the @var{expression} is 500
5396 or more, @command{@value{AS}} will print a warning message. If the value is less
5397 than 500, @command{@value{AS}} will print an error message. The message will
5398 include the value of @var{expression}. This can occasionally be useful inside
5399 complex nested macros or conditional assembly.
5402 @section @code{.file}
5403 @cindex @code{file} directive
5405 @ifclear no-file-dir
5406 There are two different versions of the @code{.file} directive. Targets
5407 that support DWARF2 line number information use the DWARF2 version of
5408 @code{.file}. Other targets use the default version.
5410 @subheading Default Version
5412 @cindex logical file name
5413 @cindex file name, logical
5414 This version of the @code{.file} directive tells @command{@value{AS}} that we
5415 are about to start a new logical file. The syntax is:
5421 @var{string} is the new file name. In general, the filename is
5422 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
5423 to specify an empty file name, you must give the quotes--@code{""}. This
5424 statement may go away in future: it is only recognized to be compatible with
5425 old @command{@value{AS}} programs.
5427 @subheading DWARF2 Version
5430 When emitting DWARF2 line number information, @code{.file} assigns filenames
5431 to the @code{.debug_line} file name table. The syntax is:
5434 .file @var{fileno} @var{filename}
5437 The @var{fileno} operand should be a unique positive integer to use as the
5438 index of the entry in the table. The @var{filename} operand is a C string
5439 literal enclosed in double quotes. The @var{filename} can include directory
5440 elements. If it does, then the directory will be added to the directory table
5441 and the basename will be added to the file table.
5443 The detail of filename indices is exposed to the user because the filename
5444 table is shared with the @code{.debug_info} section of the DWARF2 debugging
5445 information, and thus the user must know the exact indices that table
5448 If DWARF5 support has been enabled via the @option{-gdwarf-5} option then
5449 an extended version of @code{.file} is also allowed:
5452 .file @var{fileno} [@var{dirname}] @var{filename} [md5 @var{value}]
5455 With this version a separate directory name is allowed, although if this is
5456 used then @var{filename} should not contain any directory component, except
5457 for @var{fileno} equal to 0: in this case, @var{dirname} is expected to be
5458 the current directory and @var{filename} the currently processed file, and
5459 the latter need not be located in the former. In addtion an MD5 hash value
5460 of the contents of @var{filename} can be provided. This will be stored in
5461 the the file table as well, and can be used by tools reading the debug
5462 information to verify that the contents of the source file match the
5463 contents of the compiled file.
5466 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
5468 @cindex @code{fill} directive
5469 @cindex writing patterns in memory
5470 @cindex patterns, writing in memory
5471 @var{repeat}, @var{size} and @var{value} are absolute expressions.
5472 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
5473 may be zero or more. @var{Size} may be zero or more, but if it is
5474 more than 8, then it is deemed to have the value 8, compatible with
5475 other people's assemblers. The contents of each @var{repeat} bytes
5476 is taken from an 8-byte number. The highest order 4 bytes are
5477 zero. The lowest order 4 bytes are @var{value} rendered in the
5478 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
5479 Each @var{size} bytes in a repetition is taken from the lowest order
5480 @var{size} bytes of this number. Again, this bizarre behavior is
5481 compatible with other people's assemblers.
5483 @var{size} and @var{value} are optional.
5484 If the second comma and @var{value} are absent, @var{value} is
5485 assumed zero. If the first comma and following tokens are absent,
5486 @var{size} is assumed to be 1.
5489 @section @code{.float @var{flonums}}
5491 @cindex floating point numbers (single)
5492 @cindex @code{float} directive
5493 This directive assembles zero or more flonums, separated by commas. It
5494 has the same effect as @code{.single}.
5496 The exact kind of floating point numbers emitted depends on how
5497 @command{@value{AS}} is configured.
5498 @xref{Machine Dependencies}.
5502 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
5503 in @sc{ieee} format.
5508 @section @code{.func @var{name}[,@var{label}]}
5509 @cindex @code{func} directive
5510 @code{.func} emits debugging information to denote function @var{name}, and
5511 is ignored unless the file is assembled with debugging enabled.
5512 Only @samp{--gstabs[+]} is currently supported.
5513 @var{label} is the entry point of the function and if omitted @var{name}
5514 prepended with the @samp{leading char} is used.
5515 @samp{leading char} is usually @code{_} or nothing, depending on the target.
5516 All functions are currently defined to have @code{void} return type.
5517 The function must be terminated with @code{.endfunc}.
5520 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
5522 @cindex @code{global} directive
5523 @cindex symbol, making visible to linker
5524 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
5525 @var{symbol} in your partial program, its value is made available to
5526 other partial programs that are linked with it. Otherwise,
5527 @var{symbol} takes its attributes from a symbol of the same name
5528 from another file linked into the same program.
5530 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
5531 compatibility with other assemblers.
5534 On the HPPA, @code{.global} is not always enough to make it accessible to other
5535 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
5536 @xref{HPPA Directives, ,HPPA Assembler Directives}.
5541 @section @code{.gnu_attribute @var{tag},@var{value}}
5542 Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
5545 @section @code{.hidden @var{names}}
5547 @cindex @code{hidden} directive
5549 This is one of the ELF visibility directives. The other two are
5550 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
5551 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5553 This directive overrides the named symbols default visibility (which is set by
5554 their binding: local, global or weak). The directive sets the visibility to
5555 @code{hidden} which means that the symbols are not visible to other components.
5556 Such symbols are always considered to be @code{protected} as well.
5560 @section @code{.hword @var{expressions}}
5562 @cindex @code{hword} directive
5563 @cindex integers, 16-bit
5564 @cindex numbers, 16-bit
5565 @cindex sixteen bit integers
5566 This expects zero or more @var{expressions}, and emits
5567 a 16 bit number for each.
5570 This directive is a synonym for @samp{.short}; depending on the target
5571 architecture, it may also be a synonym for @samp{.word}.
5575 This directive is a synonym for @samp{.short}.
5578 This directive is a synonym for both @samp{.short} and @samp{.word}.
5583 @section @code{.ident}
5585 @cindex @code{ident} directive
5587 This directive is used by some assemblers to place tags in object files. The
5588 behavior of this directive varies depending on the target. When using the
5589 a.out object file format, @command{@value{AS}} simply accepts the directive for
5590 source-file compatibility with existing assemblers, but does not emit anything
5591 for it. When using COFF, comments are emitted to the @code{.comment} or
5592 @code{.rdata} section, depending on the target. When using ELF, comments are
5593 emitted to the @code{.comment} section.
5596 @section @code{.if @var{absolute expression}}
5598 @cindex conditional assembly
5599 @cindex @code{if} directive
5600 @code{.if} marks the beginning of a section of code which is only
5601 considered part of the source program being assembled if the argument
5602 (which must be an @var{absolute expression}) is non-zero. The end of
5603 the conditional section of code must be marked by @code{.endif}
5604 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
5605 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
5606 If you have several conditions to check, @code{.elseif} may be used to avoid
5607 nesting blocks if/else within each subsequent @code{.else} block.
5609 The following variants of @code{.if} are also supported:
5611 @cindex @code{ifdef} directive
5612 @item .ifdef @var{symbol}
5613 Assembles the following section of code if the specified @var{symbol}
5614 has been defined. Note a symbol which has been referenced but not yet defined
5615 is considered to be undefined.
5617 @cindex @code{ifb} directive
5618 @item .ifb @var{text}
5619 Assembles the following section of code if the operand is blank (empty).
5621 @cindex @code{ifc} directive
5622 @item .ifc @var{string1},@var{string2}
5623 Assembles the following section of code if the two strings are the same. The
5624 strings may be optionally quoted with single quotes. If they are not quoted,
5625 the first string stops at the first comma, and the second string stops at the
5626 end of the line. Strings which contain whitespace should be quoted. The
5627 string comparison is case sensitive.
5629 @cindex @code{ifeq} directive
5630 @item .ifeq @var{absolute expression}
5631 Assembles the following section of code if the argument is zero.
5633 @cindex @code{ifeqs} directive
5634 @item .ifeqs @var{string1},@var{string2}
5635 Another form of @code{.ifc}. The strings must be quoted using double quotes.
5637 @cindex @code{ifge} directive
5638 @item .ifge @var{absolute expression}
5639 Assembles the following section of code if the argument is greater than or
5642 @cindex @code{ifgt} directive
5643 @item .ifgt @var{absolute expression}
5644 Assembles the following section of code if the argument is greater than zero.
5646 @cindex @code{ifle} directive
5647 @item .ifle @var{absolute expression}
5648 Assembles the following section of code if the argument is less than or equal
5651 @cindex @code{iflt} directive
5652 @item .iflt @var{absolute expression}
5653 Assembles the following section of code if the argument is less than zero.
5655 @cindex @code{ifnb} directive
5656 @item .ifnb @var{text}
5657 Like @code{.ifb}, but the sense of the test is reversed: this assembles the
5658 following section of code if the operand is non-blank (non-empty).
5660 @cindex @code{ifnc} directive
5661 @item .ifnc @var{string1},@var{string2}.
5662 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
5663 following section of code if the two strings are not the same.
5665 @cindex @code{ifndef} directive
5666 @cindex @code{ifnotdef} directive
5667 @item .ifndef @var{symbol}
5668 @itemx .ifnotdef @var{symbol}
5669 Assembles the following section of code if the specified @var{symbol}
5670 has not been defined. Both spelling variants are equivalent. Note a symbol
5671 which has been referenced but not yet defined is considered to be undefined.
5673 @cindex @code{ifne} directive
5674 @item .ifne @var{absolute expression}
5675 Assembles the following section of code if the argument is not equal to zero
5676 (in other words, this is equivalent to @code{.if}).
5678 @cindex @code{ifnes} directive
5679 @item .ifnes @var{string1},@var{string2}
5680 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
5681 following section of code if the two strings are not the same.
5685 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
5687 @cindex @code{incbin} directive
5688 @cindex binary files, including
5689 The @code{incbin} directive includes @var{file} verbatim at the current
5690 location. You can control the search paths used with the @samp{-I} command-line
5691 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5694 The @var{skip} argument skips a number of bytes from the start of the
5695 @var{file}. The @var{count} argument indicates the maximum number of bytes to
5696 read. Note that the data is not aligned in any way, so it is the user's
5697 responsibility to make sure that proper alignment is provided both before and
5698 after the @code{incbin} directive.
5701 @section @code{.include "@var{file}"}
5703 @cindex @code{include} directive
5704 @cindex supporting files, including
5705 @cindex files, including
5706 This directive provides a way to include supporting files at specified
5707 points in your source program. The code from @var{file} is assembled as
5708 if it followed the point of the @code{.include}; when the end of the
5709 included file is reached, assembly of the original file continues. You
5710 can control the search paths used with the @samp{-I} command-line option
5711 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5715 @section @code{.int @var{expressions}}
5717 @cindex @code{int} directive
5718 @cindex integers, 32-bit
5719 Expect zero or more @var{expressions}, of any section, separated by commas.
5720 For each expression, emit a number that, at run time, is the value of that
5721 expression. The byte order and bit size of the number depends on what kind
5722 of target the assembly is for.
5726 On most forms of the H8/300, @code{.int} emits 16-bit
5727 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
5734 @section @code{.internal @var{names}}
5736 @cindex @code{internal} directive
5738 This is one of the ELF visibility directives. The other two are
5739 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
5740 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5742 This directive overrides the named symbols default visibility (which is set by
5743 their binding: local, global or weak). The directive sets the visibility to
5744 @code{internal} which means that the symbols are considered to be @code{hidden}
5745 (i.e., not visible to other components), and that some extra, processor specific
5746 processing must also be performed upon the symbols as well.
5750 @section @code{.irp @var{symbol},@var{values}}@dots{}
5752 @cindex @code{irp} directive
5753 Evaluate a sequence of statements assigning different values to @var{symbol}.
5754 The sequence of statements starts at the @code{.irp} directive, and is
5755 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
5756 set to @var{value}, and the sequence of statements is assembled. If no
5757 @var{value} is listed, the sequence of statements is assembled once, with
5758 @var{symbol} set to the null string. To refer to @var{symbol} within the
5759 sequence of statements, use @var{\symbol}.
5761 For example, assembling
5769 is equivalent to assembling
5777 For some caveats with the spelling of @var{symbol}, see also @ref{Macro}.
5780 @section @code{.irpc @var{symbol},@var{values}}@dots{}
5782 @cindex @code{irpc} directive
5783 Evaluate a sequence of statements assigning different values to @var{symbol}.
5784 The sequence of statements starts at the @code{.irpc} directive, and is
5785 terminated by an @code{.endr} directive. For each character in @var{value},
5786 @var{symbol} is set to the character, and the sequence of statements is
5787 assembled. If no @var{value} is listed, the sequence of statements is
5788 assembled once, with @var{symbol} set to the null string. To refer to
5789 @var{symbol} within the sequence of statements, use @var{\symbol}.
5791 For example, assembling
5799 is equivalent to assembling
5807 For some caveats with the spelling of @var{symbol}, see also the discussion
5811 @section @code{.lcomm @var{symbol} , @var{length}}
5813 @cindex @code{lcomm} directive
5814 @cindex local common symbols
5815 @cindex symbols, local common
5816 Reserve @var{length} (an absolute expression) bytes for a local common
5817 denoted by @var{symbol}. The section and value of @var{symbol} are
5818 those of the new local common. The addresses are allocated in the bss
5819 section, so that at run-time the bytes start off zeroed. @var{Symbol}
5820 is not declared global (@pxref{Global,,@code{.global}}), so is normally
5821 not visible to @code{@value{LD}}.
5824 Some targets permit a third argument to be used with @code{.lcomm}. This
5825 argument specifies the desired alignment of the symbol in the bss section.
5829 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
5830 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
5834 @section @code{.lflags}
5836 @cindex @code{lflags} directive (ignored)
5837 @command{@value{AS}} accepts this directive, for compatibility with other
5838 assemblers, but ignores it.
5840 @ifclear no-line-dir
5842 @section @code{.line @var{line-number}}
5844 @cindex @code{line} directive
5845 @cindex logical line number
5847 Change the logical line number. @var{line-number} must be an absolute
5848 expression. The next line has that logical line number. Therefore any other
5849 statements on the current line (after a statement separator character) are
5850 reported as on logical line number @var{line-number} @minus{} 1. One day
5851 @command{@value{AS}} will no longer support this directive: it is recognized only
5852 for compatibility with existing assembler programs.
5855 Even though this is a directive associated with the @code{a.out} or
5856 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
5857 when producing COFF output, and treats @samp{.line} as though it
5858 were the COFF @samp{.ln} @emph{if} it is found outside a
5859 @code{.def}/@code{.endef} pair.
5861 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
5862 used by compilers to generate auxiliary symbol information for
5867 @section @code{.linkonce [@var{type}]}
5869 @cindex @code{linkonce} directive
5870 @cindex common sections
5871 Mark the current section so that the linker only includes a single copy of it.
5872 This may be used to include the same section in several different object files,
5873 but ensure that the linker will only include it once in the final output file.
5874 The @code{.linkonce} pseudo-op must be used for each instance of the section.
5875 Duplicate sections are detected based on the section name, so it should be
5878 This directive is only supported by a few object file formats; as of this
5879 writing, the only object file format which supports it is the Portable
5880 Executable format used on Windows NT.
5882 The @var{type} argument is optional. If specified, it must be one of the
5883 following strings. For example:
5887 Not all types may be supported on all object file formats.
5891 Silently discard duplicate sections. This is the default.
5894 Warn if there are duplicate sections, but still keep only one copy.
5897 Warn if any of the duplicates have different sizes.
5900 Warn if any of the duplicates do not have exactly the same contents.
5904 @section @code{.list}
5906 @cindex @code{list} directive
5907 @cindex listing control, turning on
5908 Control (in conjunction with the @code{.nolist} directive) whether or
5909 not assembly listings are generated. These two directives maintain an
5910 internal counter (which is zero initially). @code{.list} increments the
5911 counter, and @code{.nolist} decrements it. Assembly listings are
5912 generated whenever the counter is greater than zero.
5914 By default, listings are disabled. When you enable them (with the
5915 @samp{-a} command-line option; @pxref{Invoking,,Command-Line Options}),
5916 the initial value of the listing counter is one.
5919 @section @code{.ln @var{line-number}}
5921 @cindex @code{ln} directive
5922 @ifclear no-line-dir
5923 @samp{.ln} is a synonym for @samp{.line}.
5926 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
5927 must be an absolute expression. The next line has that logical
5928 line number, so any other statements on the current line (after a
5929 statement separator character @code{;}) are reported as on logical
5930 line number @var{line-number} @minus{} 1.
5934 @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]}
5935 @cindex @code{loc} directive
5936 When emitting DWARF2 line number information,
5937 the @code{.loc} directive will add a row to the @code{.debug_line} line
5938 number matrix corresponding to the immediately following assembly
5939 instruction. The @var{fileno}, @var{lineno}, and optional @var{column}
5940 arguments will be applied to the @code{.debug_line} state machine before
5941 the row is added. It is an error for the input assembly file to generate
5942 a non-empty @code{.debug_line} and also use @code{loc} directives.
5944 The @var{options} are a sequence of the following tokens in any order:
5948 This option will set the @code{basic_block} register in the
5949 @code{.debug_line} state machine to @code{true}.
5952 This option will set the @code{prologue_end} register in the
5953 @code{.debug_line} state machine to @code{true}.
5955 @item epilogue_begin
5956 This option will set the @code{epilogue_begin} register in the
5957 @code{.debug_line} state machine to @code{true}.
5959 @item is_stmt @var{value}
5960 This option will set the @code{is_stmt} register in the
5961 @code{.debug_line} state machine to @code{value}, which must be
5964 @item isa @var{value}
5965 This directive will set the @code{isa} register in the @code{.debug_line}
5966 state machine to @var{value}, which must be an unsigned integer.
5968 @item discriminator @var{value}
5969 This directive will set the @code{discriminator} register in the @code{.debug_line}
5970 state machine to @var{value}, which must be an unsigned integer.
5972 @item view @var{value}
5973 This option causes a row to be added to @code{.debug_line} in reference to the
5974 current address (which might not be the same as that of the following assembly
5975 instruction), and to associate @var{value} with the @code{view} register in the
5976 @code{.debug_line} state machine. If @var{value} is a label, both the
5977 @code{view} register and the label are set to the number of prior @code{.loc}
5978 directives at the same program location. If @var{value} is the literal
5979 @code{0}, the @code{view} register is set to zero, and the assembler asserts
5980 that there aren't any prior @code{.loc} directives at the same program
5981 location. If @var{value} is the literal @code{-0}, the assembler arrange for
5982 the @code{view} register to be reset in this row, even if there are prior
5983 @code{.loc} directives at the same program location.
5987 @node Loc_mark_labels
5988 @section @code{.loc_mark_labels @var{enable}}
5989 @cindex @code{loc_mark_labels} directive
5990 When emitting DWARF2 line number information,
5991 the @code{.loc_mark_labels} directive makes the assembler emit an entry
5992 to the @code{.debug_line} line number matrix with the @code{basic_block}
5993 register in the state machine set whenever a code label is seen.
5994 The @var{enable} argument should be either 1 or 0, to enable or disable
5995 this function respectively.
5999 @section @code{.local @var{names}}
6001 @cindex @code{local} directive
6002 This directive, which is available for ELF targets, marks each symbol in
6003 the comma-separated list of @code{names} as a local symbol so that it
6004 will not be externally visible. If the symbols do not already exist,
6005 they will be created.
6007 For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not
6008 accept an alignment argument, which is the case for most ELF targets,
6009 the @code{.local} directive can be used in combination with @code{.comm}
6010 (@pxref{Comm}) to define aligned local common data.
6014 @section @code{.long @var{expressions}}
6016 @cindex @code{long} directive
6017 @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}.
6020 @c no one seems to know what this is for or whether this description is
6021 @c what it really ought to do
6023 @section @code{.lsym @var{symbol}, @var{expression}}
6025 @cindex @code{lsym} directive
6026 @cindex symbol, not referenced in assembly
6027 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
6028 the hash table, ensuring it cannot be referenced by name during the
6029 rest of the assembly. This sets the attributes of the symbol to be
6030 the same as the expression value:
6032 @var{other} = @var{descriptor} = 0
6033 @var{type} = @r{(section of @var{expression})}
6034 @var{value} = @var{expression}
6037 The new symbol is not flagged as external.
6041 @section @code{.macro}
6044 The commands @code{.macro} and @code{.endm} allow you to define macros that
6045 generate assembly output. For example, this definition specifies a macro
6046 @code{sum} that puts a sequence of numbers into memory:
6049 .macro sum from=0, to=5
6058 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
6070 @item .macro @var{macname}
6071 @itemx .macro @var{macname} @var{macargs} @dots{}
6072 @cindex @code{macro} directive
6073 Begin the definition of a macro called @var{macname}. If your macro
6074 definition requires arguments, specify their names after the macro name,
6075 separated by commas or spaces. You can qualify the macro argument to
6076 indicate whether all invocations must specify a non-blank value (through
6077 @samp{:@code{req}}), or whether it takes all of the remaining arguments
6078 (through @samp{:@code{vararg}}). You can supply a default value for any
6079 macro argument by following the name with @samp{=@var{deflt}}. You
6080 cannot define two macros with the same @var{macname} unless it has been
6081 subject to the @code{.purgem} directive (@pxref{Purgem}) between the two
6082 definitions. For example, these are all valid @code{.macro} statements:
6086 Begin the definition of a macro called @code{comm}, which takes no
6089 @item .macro plus1 p, p1
6090 @itemx .macro plus1 p p1
6091 Either statement begins the definition of a macro called @code{plus1},
6092 which takes two arguments; within the macro definition, write
6093 @samp{\p} or @samp{\p1} to evaluate the arguments.
6095 @item .macro reserve_str p1=0 p2
6096 Begin the definition of a macro called @code{reserve_str}, with two
6097 arguments. The first argument has a default value, but not the second.
6098 After the definition is complete, you can call the macro either as
6099 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
6100 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
6101 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
6102 @samp{0}, and @samp{\p2} evaluating to @var{b}).
6104 @item .macro m p1:req, p2=0, p3:vararg
6105 Begin the definition of a macro called @code{m}, with at least three
6106 arguments. The first argument must always have a value specified, but
6107 not the second, which instead has a default value. The third formal
6108 will get assigned all remaining arguments specified at invocation time.
6110 When you call a macro, you can specify the argument values either by
6111 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
6112 @samp{sum to=17, from=9}.
6116 Note that since each of the @var{macargs} can be an identifier exactly
6117 as any other one permitted by the target architecture, there may be
6118 occasional problems if the target hand-crafts special meanings to certain
6119 characters when they occur in a special position. For example, if the colon
6120 (@code{:}) is generally permitted to be part of a symbol name, but the
6121 architecture specific code special-cases it when occurring as the final
6122 character of a symbol (to denote a label), then the macro parameter
6123 replacement code will have no way of knowing that and consider the whole
6124 construct (including the colon) an identifier, and check only this
6125 identifier for being the subject to parameter substitution. So for example
6126 this macro definition:
6134 might not work as expected. Invoking @samp{label foo} might not create a label
6135 called @samp{foo} but instead just insert the text @samp{\l:} into the
6136 assembler source, probably generating an error about an unrecognised
6139 Similarly problems might occur with the period character (@samp{.})
6140 which is often allowed inside opcode names (and hence identifier names). So
6141 for example constructing a macro to build an opcode from a base name and a
6142 length specifier like this:
6145 .macro opcode base length
6150 and invoking it as @samp{opcode store l} will not create a @samp{store.l}
6151 instruction but instead generate some kind of error as the assembler tries to
6152 interpret the text @samp{\base.\length}.
6154 There are several possible ways around this problem:
6157 @item Insert white space
6158 If it is possible to use white space characters then this is the simplest
6167 @item Use @samp{\()}
6168 The string @samp{\()} can be used to separate the end of a macro argument from
6169 the following text. eg:
6172 .macro opcode base length
6177 @item Use the alternate macro syntax mode
6178 In the alternative macro syntax mode the ampersand character (@samp{&}) can be
6179 used as a separator. eg:
6189 Note: this problem of correctly identifying string parameters to pseudo ops
6190 also applies to the identifiers used in @code{.irp} (@pxref{Irp})
6191 and @code{.irpc} (@pxref{Irpc}) as well.
6193 Another issue can occur with the actual arguments passed during macro
6194 invocation: Multiple arguments can be separated by blanks or commas. To have
6195 arguments actually contain blanks or commas (or potentially other non-alpha-
6196 numeric characters), individual arguments will need to be enclosed in either
6197 parentheses @code{()}, square brackets @code{[]}, or double quote @code{"}
6198 characters. The latter may be the only viable option in certain situations,
6199 as only double quotes are actually stripped while establishing arguments. It
6200 may be important to be aware of two escaping models used when processing such
6201 quoted argument strings: For one two adjacent double quotes represent a single
6202 double quote in the resulting argument, going along the lines of the stripping
6203 of the enclosing quotes. But then double quotes can also be escaped by a
6204 backslash @code{\}, but this backslash will not be retained in the resulting
6205 actual argument as then seen / used while expanding the macro.
6207 As a consequence to the first of these escaping mechanisms two string literals
6208 intended to be representing separate macro arguments need to be separated by
6209 white space (or, better yet, by a comma). To state it differently, such
6210 adjacent string literals - even if separated only by a blank - will not be
6211 concatenated when determining macro arguments, even if they're only separated
6212 by white space. This is unlike certain other pseudo ops, e.g. @code{.ascii}.
6215 @cindex @code{endm} directive
6216 Mark the end of a macro definition.
6219 @cindex @code{exitm} directive
6220 Exit early from the current macro definition.
6222 @cindex number of macros executed
6223 @cindex macros, count executed
6225 @command{@value{AS}} maintains a counter of how many macros it has
6226 executed in this pseudo-variable; you can copy that number to your
6227 output with @samp{\@@}, but @emph{only within a macro definition}.
6229 @item LOCAL @var{name} [ , @dots{} ]
6230 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
6231 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
6232 @xref{Altmacro,,@code{.altmacro}}.
6236 @section @code{.mri @var{val}}
6238 @cindex @code{mri} directive
6239 @cindex MRI mode, temporarily
6240 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
6241 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
6242 affects code assembled until the next @code{.mri} directive, or until the end
6243 of the file. @xref{M, MRI mode, MRI mode}.
6246 @section @code{.noaltmacro}
6247 Disable alternate macro mode. @xref{Altmacro}.
6250 @section @code{.nolist}
6252 @cindex @code{nolist} directive
6253 @cindex listing control, turning off
6254 Control (in conjunction with the @code{.list} directive) whether or
6255 not assembly listings are generated. These two directives maintain an
6256 internal counter (which is zero initially). @code{.list} increments the
6257 counter, and @code{.nolist} decrements it. Assembly listings are
6258 generated whenever the counter is greater than zero.
6261 @section @code{.nop [@var{size}]}
6263 @cindex @code{nop} directive
6264 @cindex filling memory with no-op instructions
6265 This directive emits no-op instructions. It is provided on all architectures,
6266 allowing the creation of architecture neutral tests involving actual code. The
6267 size of the generated instruction is target specific, but if the optional
6268 @var{size} argument is given and resolves to an absolute positive value at that
6269 point in assembly (no forward expressions allowed) then the fewest no-op
6270 instructions are emitted that equal or exceed a total @var{size} in bytes.
6271 @code{.nop} does affect the generation of DWARF debug line information.
6272 Some targets do not support using @code{.nop} with @var{size}.
6275 @section @code{.nops @var{size}[, @var{control}]}
6277 @cindex @code{nops} directive
6278 @cindex filling memory with no-op instructions
6279 This directive emits no-op instructions. It is specific to the Intel 80386 and
6280 AMD x86-64 targets. It takes a @var{size} argument and generates @var{size}
6281 bytes of no-op instructions. @var{size} must be absolute and positive. These
6282 bytes do not affect the generation of DWARF debug line information.
6284 The optional @var{control} argument specifies a size limit for a single no-op
6285 instruction. If not provided then a value of 0 is assumed. The valid values
6286 of @var{control} are between 0 and 4 in 16-bit mode, between 0 and 7 when
6287 tuning for older processors in 32-bit mode, between 0 and 11 in 64-bit mode or
6288 when tuning for newer processors in 32-bit mode. When 0 is used, the no-op
6289 instruction size limit is set to the maximum supported size.
6292 @section @code{.octa @var{bignums}}
6294 @c FIXME: double size emitted for "octa" on some? Or warn?
6295 @cindex @code{octa} directive
6296 @cindex integer, 16-byte
6297 @cindex sixteen byte integer
6298 This directive expects zero or more bignums, separated by commas. For each
6299 bignum, it emits a 16-byte integer.
6301 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
6302 hence @emph{octa}-word for 16 bytes.
6305 @section @code{.offset @var{loc}}
6307 @cindex @code{offset} directive
6308 Set the location counter to @var{loc} in the absolute section. @var{loc} must
6309 be an absolute expression. This directive may be useful for defining
6310 symbols with absolute values. Do not confuse it with the @code{.org}
6314 @section @code{.org @var{new-lc} , @var{fill}}
6316 @cindex @code{org} directive
6317 @cindex location counter, advancing
6318 @cindex advancing location counter
6319 @cindex current address, advancing
6320 Advance the location counter of the current section to
6321 @var{new-lc}. @var{new-lc} is either an absolute expression or an
6322 expression with the same section as the current subsection. That is,
6323 you can't use @code{.org} to cross sections: if @var{new-lc} has the
6324 wrong section, the @code{.org} directive is ignored. To be compatible
6325 with former assemblers, if the section of @var{new-lc} is absolute,
6326 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
6327 is the same as the current subsection.
6329 @code{.org} may only increase the location counter, or leave it
6330 unchanged; you cannot use @code{.org} to move the location counter
6333 @c double negative used below "not undefined" because this is a specific
6334 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
6335 @c section. doc@cygnus.com 18feb91
6336 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
6337 may not be undefined. If you really detest this restriction we eagerly await
6338 a chance to share your improved assembler.
6340 Beware that the origin is relative to the start of the section, not
6341 to the start of the subsection. This is compatible with other
6342 people's assemblers.
6344 When the location counter (of the current subsection) is advanced, the
6345 intervening bytes are filled with @var{fill} which should be an
6346 absolute expression. If the comma and @var{fill} are omitted,
6347 @var{fill} defaults to zero.
6350 @section @code{.p2align[wl] [@var{abs-expr}[, @var{abs-expr}[, @var{abs-expr}]]]}
6352 @cindex padding the location counter given a power of two
6353 @cindex @code{p2align} directive
6354 Pad the location counter (in the current subsection) to a particular
6355 storage boundary. The first expression (which must be absolute) is the
6356 number of low-order zero bits the location counter must have after
6357 advancement. For example @samp{.p2align 3} advances the location
6358 counter until it is a multiple of 8. If the location counter is already a
6359 multiple of 8, no change is needed. If the expression is omitted then a
6360 default value of 0 is used, effectively disabling alignment requirements.
6362 The second expression (also absolute) gives the fill value to be stored in the
6363 padding bytes. It (and the comma) may be omitted. If it is omitted, the
6364 padding bytes are normally zero. However, on most systems, if the section is
6365 marked as containing code and the fill value is omitted, the space is filled
6366 with no-op instructions.
6368 The third expression is also absolute, and is also optional. If it is present,
6369 it is the maximum number of bytes that should be skipped by this alignment
6370 directive. If doing the alignment would require skipping more bytes than the
6371 specified maximum, then the alignment is not done at all. You can omit the
6372 fill value (the second argument) entirely by simply using two commas after the
6373 required alignment; this can be useful if you want the alignment to be filled
6374 with no-op instructions when appropriate.
6376 @cindex @code{p2alignw} directive
6377 @cindex @code{p2alignl} directive
6378 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
6379 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
6380 pattern as a two byte word value. The @code{.p2alignl} directives treats the
6381 fill pattern as a four byte longword value. For example, @code{.p2alignw
6382 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
6383 filled in with the value 0x368d (the exact placement of the bytes depends upon
6384 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
6389 @section @code{.popsection}
6391 @cindex @code{popsection} directive
6392 @cindex Section Stack
6393 This is one of the ELF section stack manipulation directives. The others are
6394 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
6395 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
6398 This directive replaces the current section (and subsection) with the top
6399 section (and subsection) on the section stack. This section is popped off the
6405 @section @code{.previous}
6407 @cindex @code{previous} directive
6408 @cindex Section Stack
6409 This is one of the ELF section stack manipulation directives. The others are
6410 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
6411 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
6412 (@pxref{PopSection}).
6414 This directive swaps the current section (and subsection) with most recently
6415 referenced section/subsection pair prior to this one. Multiple
6416 @code{.previous} directives in a row will flip between two sections (and their
6417 subsections). For example:
6429 Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
6435 # Now in section A subsection 1
6439 # Now in section B subsection 0
6442 # Now in section B subsection 1
6445 # Now in section B subsection 0
6449 Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
6450 section B and 0x9abc into subsection 1 of section B.
6452 In terms of the section stack, this directive swaps the current section with
6453 the top section on the section stack.
6457 @section @code{.print @var{string}}
6459 @cindex @code{print} directive
6460 @command{@value{AS}} will print @var{string} on the standard output during
6461 assembly. You must put @var{string} in double quotes.
6465 @section @code{.protected @var{names}}
6467 @cindex @code{protected} directive
6469 This is one of the ELF visibility directives. The other two are
6470 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
6472 This directive overrides the named symbols default visibility (which is set by
6473 their binding: local, global or weak). The directive sets the visibility to
6474 @code{protected} which means that any references to the symbols from within the
6475 components that defines them must be resolved to the definition in that
6476 component, even if a definition in another component would normally preempt
6481 @section @code{.psize @var{lines} , @var{columns}}
6483 @cindex @code{psize} directive
6484 @cindex listing control: paper size
6485 @cindex paper size, for listings
6486 Use this directive to declare the number of lines---and, optionally, the
6487 number of columns---to use for each page, when generating listings.
6489 If you do not use @code{.psize}, listings use a default line-count
6490 of 60. You may omit the comma and @var{columns} specification; the
6491 default width is 200 columns.
6493 @command{@value{AS}} generates formfeeds whenever the specified number of
6494 lines is exceeded (or whenever you explicitly request one, using
6497 If you specify @var{lines} as @code{0}, no formfeeds are generated save
6498 those explicitly specified with @code{.eject}.
6501 @section @code{.purgem @var{name}}
6503 @cindex @code{purgem} directive
6504 Undefine the macro @var{name}, so that later uses of the string will not be
6505 expanded. @xref{Macro}.
6509 @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]}
6511 @cindex @code{pushsection} directive
6512 @cindex Section Stack
6513 This is one of the ELF section stack manipulation directives. The others are
6514 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
6515 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6518 This directive pushes the current section (and subsection) onto the
6519 top of the section stack, and then replaces the current section and
6520 subsection with @code{name} and @code{subsection}. The optional
6521 @code{flags}, @code{type} and @code{arguments} are treated the same
6522 as in the @code{.section} (@pxref{Section}) directive.
6526 @section @code{.quad @var{bignums}}
6528 @cindex @code{quad} directive
6529 @code{.quad} expects zero or more bignums, separated by commas. For
6530 each bignum, it emits
6532 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
6533 warning message; and just takes the lowest order 8 bytes of the bignum.
6534 @cindex eight-byte integer
6535 @cindex integer, 8-byte
6537 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
6538 hence @emph{quad}-word for 8 bytes.
6541 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
6542 warning message; and just takes the lowest order 16 bytes of the bignum.
6543 @cindex sixteen-byte integer
6544 @cindex integer, 16-byte
6548 @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
6550 @cindex @code{reloc} directive
6551 Generate a relocation at @var{offset} of type @var{reloc_name} with value
6552 @var{expression}. If @var{offset} is a number, the relocation is generated in
6553 the current section. If @var{offset} is an expression that resolves to a
6554 symbol plus offset, the relocation is generated in the given symbol's section.
6555 @var{expression}, if present, must resolve to a symbol plus addend or to an
6556 absolute value, but note that not all targets support an addend. e.g. ELF REL
6557 targets such as i386 store an addend in the section contents rather than in the
6558 relocation. This low level interface does not support addends stored in the
6562 @section @code{.rept @var{count}}
6564 @cindex @code{rept} directive
6565 Repeat the sequence of lines between the @code{.rept} directive and the next
6566 @code{.endr} directive @var{count} times.
6568 For example, assembling
6576 is equivalent to assembling
6584 A count of zero is allowed, but nothing is generated. Negative counts are not
6585 allowed and if encountered will be treated as if they were zero.
6588 @section @code{.sbttl "@var{subheading}"}
6590 @cindex @code{sbttl} directive
6591 @cindex subtitles for listings
6592 @cindex listing control: subtitle
6593 Use @var{subheading} as the title (third line, immediately after the
6594 title line) when generating assembly listings.
6596 This directive affects subsequent pages, as well as the current page if
6597 it appears within ten lines of the top of a page.
6601 @section @code{.scl @var{class}}
6603 @cindex @code{scl} directive
6604 @cindex symbol storage class (COFF)
6605 @cindex COFF symbol storage class
6606 Set the storage-class value for a symbol. This directive may only be
6607 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
6608 whether a symbol is static or external, or it may record further
6609 symbolic debugging information.
6614 @section @code{.section @var{name}}
6616 @cindex named section
6617 Use the @code{.section} directive to assemble the following code into a section
6620 This directive is only supported for targets that actually support arbitrarily
6621 named sections; on @code{a.out} targets, for example, it is not accepted, even
6622 with a standard @code{a.out} section name.
6626 @c only print the extra heading if both COFF and ELF are set
6627 @subheading COFF Version
6630 @cindex @code{section} directive (COFF version)
6631 For COFF targets, the @code{.section} directive is used in one of the following
6635 .section @var{name}[, "@var{flags}"]
6636 .section @var{name}[, @var{subsection}]
6639 If the optional argument is quoted, it is taken as flags to use for the
6640 section. Each flag is a single character. The following flags are recognized:
6644 bss section (uninitialized data)
6646 section is not loaded
6652 exclude section from linking
6658 shared section (meaningful for PE targets)
6660 ignored. (For compatibility with the ELF version)
6662 section is not readable (meaningful for PE targets)
6664 single-digit power-of-two section alignment (GNU extension)
6667 If no flags are specified, the default flags depend upon the section name. If
6668 the section name is not recognized, the default will be for the section to be
6669 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
6670 from the section, rather than adding them, so if they are used on their own it
6671 will be as if no flags had been specified at all.
6673 If the optional argument to the @code{.section} directive is not quoted, it is
6674 taken as a subsection number (@pxref{Sub-Sections}).
6679 @c only print the extra heading if both COFF and ELF are set
6680 @subheading ELF Version
6683 @cindex Section Stack
6684 This is one of the ELF section stack manipulation directives. The others are
6685 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
6686 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
6687 @code{.previous} (@pxref{Previous}).
6689 @cindex @code{section} directive (ELF version)
6690 For ELF targets, the @code{.section} directive is used like this:
6693 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]]
6696 @anchor{Section Name Substitutions}
6697 @kindex --sectname-subst
6698 @cindex section name substitution
6699 If the @samp{--sectname-subst} command-line option is provided, the @var{name}
6700 argument may contain a substitution sequence. Only @code{%S} is supported
6701 at the moment, and substitutes the current section name. For example:
6704 .macro exception_code
6705 .section %S.exception
6706 [exception code here]
6721 The two @code{exception_code} invocations above would create the
6722 @code{.text.exception} and @code{.init.exception} sections respectively.
6723 This is useful e.g. to discriminate between ancillary sections that are
6724 tied to setup code to be discarded after use from ancillary sections that
6725 need to stay resident without having to define multiple @code{exception_code}
6726 macros just for that purpose.
6728 The optional @var{flags} argument is a quoted string which may contain any
6729 combination of the following characters:
6733 section is allocatable
6735 section is a GNU_MBIND section
6737 section is excluded from executable and shared library.
6739 section references a symbol defined in another section (the linked-to
6740 section) in the same file.
6744 section is executable
6746 section is mergeable
6748 section contains zero terminated strings
6750 section is a member of a section group
6752 section is used for thread-local-storage
6754 section is a member of the previously-current section's group, if any
6756 retained section (apply SHF_GNU_RETAIN to prevent linker garbage
6757 collection, GNU ELF extension)
6758 @item @code{<number>}
6759 a numeric value indicating the bits to be set in the ELF section header's flags
6760 field. Note - if one or more of the alphabetic characters described above is
6761 also included in the flags field, their bit values will be ORed into the
6763 @item @code{<target specific>}
6764 some targets extend this list with their own flag characters
6767 Note - once a section's flags have been set they cannot be changed. There are
6768 a few exceptions to this rule however. Processor and application specific
6769 flags can be added to an already defined section. The @code{.interp},
6770 @code{.strtab} and @code{.symtab} sections can have the allocate flag
6771 (@code{a}) set after they are initially defined, and the @code{.note-GNU-stack}
6772 section may have the executable (@code{x}) flag added. Also note that the
6773 @code{.attach_to_group} directive can be used to add a section to a group even
6774 if the section was not originally declared to be part of that group.
6776 The optional @var{type} argument may contain one of the following constants:
6780 section contains data
6782 section does not contain data (i.e., section only occupies space)
6784 section contains data which is used by things other than the program
6786 section contains an array of pointers to init functions
6788 section contains an array of pointers to finish functions
6789 @item @@preinit_array
6790 section contains an array of pointers to pre-init functions
6791 @item @@@code{<number>}
6792 a numeric value to be set as the ELF section header's type field.
6793 @item @@@code{<target specific>}
6794 some targets extend this list with their own types
6797 Many targets only support the first three section types. The type may be
6798 enclosed in double quotes if necessary.
6800 Note on targets where the @code{@@} character is the start of a comment (eg
6801 ARM) then another character is used instead. For example the ARM port uses the
6804 Note - some sections, eg @code{.text} and @code{.data} are considered to be
6805 special and have fixed types. Any attempt to declare them with a different
6806 type will generate an error from the assembler.
6808 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
6809 be specified as well as an extra argument---@var{entsize}---like this:
6812 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
6815 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
6816 constants, each @var{entsize} octets long. Sections with both @code{M} and
6817 @code{S} must contain zero terminated strings where each character is
6818 @var{entsize} bytes long. The linker may remove duplicates within sections with
6819 the same name, same entity size and same flags. @var{entsize} must be an
6820 absolute expression. For sections with both @code{M} and @code{S}, a string
6821 which is a suffix of a larger string is considered a duplicate. Thus
6822 @code{"def"} will be merged with @code{"abcdef"}; A reference to the first
6823 @code{"def"} will be changed to a reference to @code{"abcdef"+3}.
6825 If @var{flags} contains the @code{o} flag, then the @var{type} argument
6826 must be present along with an additional field like this:
6829 .section @var{name},"@var{flags}"o,@@@var{type},@var{SymbolName}|@var{SectionIndex}
6832 The @var{SymbolName} field specifies the symbol name which the section
6833 references. Alternatively a numeric @var{SectionIndex} can be provided. This
6834 is not generally a good idea as section indicies are rarely known at assembly
6835 time, but the facility is provided for testing purposes. An index of zero is
6836 allowed. It indicates that the linked-to section has already been discarded.
6838 Note: If both the @var{M} and @var{o} flags are present, then the fields
6839 for the Merge flag should come first, like this:
6842 .section @var{name},"@var{flags}"Mo,@@@var{type},@var{entsize},@var{SymbolName}
6845 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
6846 be present along with an additional field like this:
6849 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
6852 The @var{GroupName} field specifies the name of the section group to which this
6853 particular section belongs. The optional linkage field can contain:
6857 indicates that only one copy of this section should be retained
6862 Note: if both the @var{M} and @var{G} flags are present then the fields for
6863 the Merge flag should come first, like this:
6866 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
6869 If both @code{o} flag and @code{G} flag are present, then the
6870 @var{SymbolName} field for @code{o} comes first, like this:
6873 .section @var{name},"@var{flags}"oG,@@@var{type},@var{SymbolName},@var{GroupName}[,@var{linkage}]
6876 If @var{flags} contains the @code{?} symbol then it may not also contain the
6877 @code{G} symbol and the @var{GroupName} or @var{linkage} fields should not be
6878 present. Instead, @code{?} says to consider the section that's current before
6879 this directive. If that section used @code{G}, then the new section will use
6880 @code{G} with those same @var{GroupName} and @var{linkage} fields implicitly.
6881 If not, then the @code{?} symbol has no effect.
6883 The optional @var{unique,@code{<number>}} argument must come last. It
6884 assigns @var{@code{<number>}} as a unique section ID to distinguish
6885 different sections with the same section name like these:
6888 .section @var{name},"@var{flags}",@@@var{type},@var{unique,@code{<number>}}
6889 .section @var{name},"@var{flags}"G,@@@var{type},@var{GroupName},[@var{linkage}],@var{unique,@code{<number>}}
6890 .section @var{name},"@var{flags}"MG,@@@var{type},@var{entsize},@var{GroupName}[,@var{linkage}],@var{unique,@code{<number>}}
6893 The valid values of @var{@code{<number>}} are between 0 and 4294967295.
6895 If no flags are specified, the default flags depend upon the section name. If
6896 the section name is not recognized, the default will be for the section to have
6897 none of the above flags: it will not be allocated in memory, nor writable, nor
6898 executable. The section will contain data.
6900 For ELF targets, the assembler supports another type of @code{.section}
6901 directive for compatibility with the Solaris assembler:
6904 .section "@var{name}"[, @var{flags}...]
6907 Note that the section name is quoted. There may be a sequence of comma
6912 section is allocatable
6916 section is executable
6918 section is excluded from executable and shared library.
6920 section is used for thread local storage
6923 This directive replaces the current section and subsection. See the
6924 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
6925 some examples of how this directive and the other section stack directives
6931 @section @code{.set @var{symbol}, @var{expression}}
6933 @cindex @code{set} directive
6934 @cindex symbol value, setting
6935 Set the value of @var{symbol} to @var{expression}. This
6936 changes @var{symbol}'s value and type to conform to
6937 @var{expression}. If @var{symbol} was flagged as external, it remains
6938 flagged (@pxref{Symbol Attributes}).
6940 You may @code{.set} a symbol many times in the same assembly provided that the
6941 values given to the symbol are constants. Values that are based on expressions
6942 involving other symbols are allowed, but some targets may restrict this to only
6943 being done once per assembly. This is because those targets do not set the
6944 addresses of symbols at assembly time, but rather delay the assignment until a
6945 final link is performed. This allows the linker a chance to change the code in
6946 the files, changing the location of, and the relative distance between, various
6949 If you @code{.set} a global symbol, the value stored in the object
6950 file is the last value stored into it.
6953 On Z80 @code{set} is a real instruction, use @code{.set} or
6954 @samp{@var{symbol} defl @var{expression}} instead.
6958 @section @code{.short @var{expressions}}
6960 @cindex @code{short} directive
6962 @code{.short} is normally the same as @samp{.word}.
6963 @xref{Word,,@code{.word}}.
6965 In some configurations, however, @code{.short} and @code{.word} generate
6966 numbers of different lengths. @xref{Machine Dependencies}.
6970 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
6973 This expects zero or more @var{expressions}, and emits
6974 a 16 bit number for each.
6979 @section @code{.single @var{flonums}}
6981 @cindex @code{single} directive
6982 @cindex floating point numbers (single)
6983 This directive assembles zero or more flonums, separated by commas. It
6984 has the same effect as @code{.float}.
6986 The exact kind of floating point numbers emitted depends on how
6987 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
6991 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
6992 numbers in @sc{ieee} format.
6998 @section @code{.size}
7000 This directive is used to set the size associated with a symbol.
7004 @c only print the extra heading if both COFF and ELF are set
7005 @subheading COFF Version
7008 @cindex @code{size} directive (COFF version)
7009 For COFF targets, the @code{.size} directive is only permitted inside
7010 @code{.def}/@code{.endef} pairs. It is used like this:
7013 .size @var{expression}
7020 @c only print the extra heading if both COFF and ELF are set
7021 @subheading ELF Version
7024 @cindex @code{size} directive (ELF version)
7025 For ELF targets, the @code{.size} directive is used like this:
7028 .size @var{name} , @var{expression}
7031 This directive sets the size associated with a symbol @var{name}.
7032 The size in bytes is computed from @var{expression} which can make use of label
7033 arithmetic. This directive is typically used to set the size of function
7038 @ifclear no-space-dir
7040 @section @code{.skip @var{size} [,@var{fill}]}
7042 @cindex @code{skip} directive
7043 @cindex filling memory
7044 This directive emits @var{size} bytes, each of value @var{fill}. Both
7045 @var{size} and @var{fill} are absolute expressions. If the comma and
7046 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
7051 @section @code{.sleb128 @var{expressions}}
7053 @cindex @code{sleb128} directive
7054 @var{sleb128} stands for ``signed little endian base 128.'' This is a
7055 compact, variable length representation of numbers used by the DWARF
7056 symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}.
7058 @ifclear no-space-dir
7060 @section @code{.space @var{size} [,@var{fill}]}
7062 @cindex @code{space} directive
7063 @cindex filling memory
7064 This directive emits @var{size} bytes, each of value @var{fill}. Both
7065 @var{size} and @var{fill} are absolute expressions. If the comma
7066 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
7071 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
7072 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
7073 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
7074 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
7082 @section @code{.stabd, .stabn, .stabs}
7084 @cindex symbolic debuggers, information for
7085 @cindex @code{stab@var{x}} directives
7086 There are three directives that begin @samp{.stab}.
7087 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
7088 The symbols are not entered in the @command{@value{AS}} hash table: they
7089 cannot be referenced elsewhere in the source file.
7090 Up to five fields are required:
7094 This is the symbol's name. It may contain any character except
7095 @samp{\000}, so is more general than ordinary symbol names. Some
7096 debuggers used to code arbitrarily complex structures into symbol names
7100 An absolute expression. The symbol's type is set to the low 8 bits of
7101 this expression. Any bit pattern is permitted, but @code{@value{LD}}
7102 and debuggers choke on silly bit patterns.
7105 An absolute expression. The symbol's ``other'' attribute is set to the
7106 low 8 bits of this expression.
7109 An absolute expression. The symbol's descriptor is set to the low 16
7110 bits of this expression.
7113 An absolute expression which becomes the symbol's value.
7116 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
7117 or @code{.stabs} statement, the symbol has probably already been created;
7118 you get a half-formed symbol in your object file. This is
7119 compatible with earlier assemblers!
7122 @cindex @code{stabd} directive
7123 @item .stabd @var{type} , @var{other} , @var{desc}
7125 The ``name'' of the symbol generated is not even an empty string.
7126 It is a null pointer, for compatibility. Older assemblers used a
7127 null pointer so they didn't waste space in object files with empty
7130 The symbol's value is set to the location counter,
7131 relocatably. When your program is linked, the value of this symbol
7132 is the address of the location counter when the @code{.stabd} was
7135 @cindex @code{stabn} directive
7136 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
7137 The name of the symbol is set to the empty string @code{""}.
7139 @cindex @code{stabs} directive
7140 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
7141 All five fields are specified.
7147 @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
7148 "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
7150 @cindex string, copying to object file
7151 @cindex string8, copying to object file
7152 @cindex string16, copying to object file
7153 @cindex string32, copying to object file
7154 @cindex string64, copying to object file
7155 @cindex @code{string} directive
7156 @cindex @code{string8} directive
7157 @cindex @code{string16} directive
7158 @cindex @code{string32} directive
7159 @cindex @code{string64} directive
7161 Copy the characters in @var{str} to the object file. You may specify more than
7162 one string to copy, separated by commas. Unless otherwise specified for a
7163 particular machine, the assembler marks the end of each string with a 0 byte.
7164 You can use any of the escape sequences described in @ref{Strings,,Strings}.
7166 The variants @code{string16}, @code{string32} and @code{string64} differ from
7167 the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
7168 copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
7169 are stored in target endianness byte order.
7175 .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
7176 .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
7181 @section @code{.struct @var{expression}}
7183 @cindex @code{struct} directive
7184 Switch to the absolute section, and set the section offset to @var{expression},
7185 which must be an absolute expression. You might use this as follows:
7194 This would define the symbol @code{field1} to have the value 0, the symbol
7195 @code{field2} to have the value 4, and the symbol @code{field3} to have the
7196 value 8. Assembly would be left in the absolute section, and you would need to
7197 use a @code{.section} directive of some sort to change to some other section
7198 before further assembly.
7202 @section @code{.subsection @var{name}}
7204 @cindex @code{subsection} directive
7205 @cindex Section Stack
7206 This is one of the ELF section stack manipulation directives. The others are
7207 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
7208 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
7211 This directive replaces the current subsection with @code{name}. The current
7212 section is not changed. The replaced subsection is put onto the section stack
7213 in place of the then current top of stack subsection.
7218 @section @code{.symver}
7219 @cindex @code{symver} directive
7220 @cindex symbol versioning
7221 @cindex versions of symbols
7222 Use the @code{.symver} directive to bind symbols to specific version nodes
7223 within a source file. This is only supported on ELF platforms, and is
7224 typically used when assembling files to be linked into a shared library.
7225 There are cases where it may make sense to use this in objects to be bound
7226 into an application itself so as to override a versioned symbol from a
7229 For ELF targets, the @code{.symver} directive can be used like this:
7231 .symver @var{name}, @var{name2@@nodename}[ ,@var{visibility}]
7233 If the original symbol @var{name} is defined within the file
7234 being assembled, the @code{.symver} directive effectively creates a symbol
7235 alias with the name @var{name2@@nodename}, and in fact the main reason that we
7236 just don't try and create a regular alias is that the @var{@@} character isn't
7237 permitted in symbol names. The @var{name2} part of the name is the actual name
7238 of the symbol by which it will be externally referenced. The name @var{name}
7239 itself is merely a name of convenience that is used so that it is possible to
7240 have definitions for multiple versions of a function within a single source
7241 file, and so that the compiler can unambiguously know which version of a
7242 function is being mentioned. The @var{nodename} portion of the alias should be
7243 the name of a node specified in the version script supplied to the linker when
7244 building a shared library. If you are attempting to override a versioned
7245 symbol from a shared library, then @var{nodename} should correspond to the
7246 nodename of the symbol you are trying to override. The optional argument
7247 @var{visibility} updates the visibility of the original symbol. The valid
7248 visibilities are @code{local}, @code{hidden}, and @code{remove}. The
7249 @code{local} visibility makes the original symbol a local symbol
7250 (@pxref{Local}). The @code{hidden} visibility sets the visibility of the
7251 original symbol to @code{hidden} (@pxref{Hidden}). The @code{remove}
7252 visibility removes the original symbol from the symbol table. If visibility
7253 isn't specified, the original symbol is unchanged.
7255 If the symbol @var{name} is not defined within the file being assembled, all
7256 references to @var{name} will be changed to @var{name2@@nodename}. If no
7257 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
7260 Another usage of the @code{.symver} directive is:
7262 .symver @var{name}, @var{name2@@@@nodename}
7264 In this case, the symbol @var{name} must exist and be defined within
7265 the file being assembled. It is similar to @var{name2@@nodename}. The
7266 difference is @var{name2@@@@nodename} will also be used to resolve
7267 references to @var{name2} by the linker.
7269 The third usage of the @code{.symver} directive is:
7271 .symver @var{name}, @var{name2@@@@@@nodename}
7273 When @var{name} is not defined within the
7274 file being assembled, it is treated as @var{name2@@nodename}. When
7275 @var{name} is defined within the file being assembled, the symbol
7276 name, @var{name}, will be changed to @var{name2@@@@nodename}.
7281 @section @code{.tag @var{structname}}
7283 @cindex COFF structure debugging
7284 @cindex structure debugging, COFF
7285 @cindex @code{tag} directive
7286 This directive is generated by compilers to include auxiliary debugging
7287 information in the symbol table. It is only permitted inside
7288 @code{.def}/@code{.endef} pairs. Tags are used to link structure
7289 definitions in the symbol table with instances of those structures.
7293 @section @code{.text @var{subsection}}
7295 @cindex @code{text} directive
7296 Tells @command{@value{AS}} to assemble the following statements onto the end of
7297 the text subsection numbered @var{subsection}, which is an absolute
7298 expression. If @var{subsection} is omitted, subsection number zero
7302 @section @code{.title "@var{heading}"}
7304 @cindex @code{title} directive
7305 @cindex listing control: title line
7306 Use @var{heading} as the title (second line, immediately after the
7307 source file name and pagenumber) when generating assembly listings.
7309 This directive affects subsequent pages, as well as the current page if
7310 it appears within ten lines of the top of a page.
7314 @section @code{.tls_common @var{symbol}, @var{length}[, @var{alignment}]}
7316 @cindex @code{tls_common} directive
7317 This directive behaves in the same way as the @code{.comm} directive
7318 (@pxref{Comm}) except that @var{symbol} has type of STT_TLS instead of
7324 @section @code{.type}
7326 This directive is used to set the type of a symbol.
7330 @c only print the extra heading if both COFF and ELF are set
7331 @subheading COFF Version
7334 @cindex COFF symbol type
7335 @cindex symbol type, COFF
7336 @cindex @code{type} directive (COFF version)
7337 For COFF targets, this directive is permitted only within
7338 @code{.def}/@code{.endef} pairs. It is used like this:
7344 This records the integer @var{int} as the type attribute of a symbol table
7351 @c only print the extra heading if both COFF and ELF are set
7352 @subheading ELF Version
7355 @cindex ELF symbol type
7356 @cindex symbol type, ELF
7357 @cindex @code{type} directive (ELF version)
7358 For ELF targets, the @code{.type} directive is used like this:
7361 .type @var{name} , @var{type description}
7364 This sets the type of symbol @var{name} to be either a
7365 function symbol or an object symbol. There are five different syntaxes
7366 supported for the @var{type description} field, in order to provide
7367 compatibility with various other assemblers.
7369 Because some of the characters used in these syntaxes (such as @samp{@@} and
7370 @samp{#}) are comment characters for some architectures, some of the syntaxes
7371 below do not work on all architectures. The first variant will be accepted by
7372 the GNU assembler on all architectures so that variant should be used for
7373 maximum portability, if you do not need to assemble your code with other
7376 The syntaxes supported are:
7379 .type <name> STT_<TYPE_IN_UPPER_CASE>
7380 .type <name>,#<type>
7381 .type <name>,@@<type>
7382 .type <name>,%<type>
7383 .type <name>,"<type>"
7386 The types supported are:
7391 Mark the symbol as being a function name.
7394 @itemx gnu_indirect_function
7395 Mark the symbol as an indirect function when evaluated during reloc
7396 processing. (This is only supported on assemblers targeting GNU systems).
7400 Mark the symbol as being a data object.
7404 Mark the symbol as being a thread-local data object.
7408 Mark the symbol as being a common data object.
7412 Does not mark the symbol in any way. It is supported just for completeness.
7414 @item gnu_unique_object
7415 Marks the symbol as being a globally unique data object. The dynamic linker
7416 will make sure that in the entire process there is just one symbol with this
7417 name and type in use. (This is only supported on assemblers targeting GNU
7422 Changing between incompatible types other than from/to STT_NOTYPE will
7423 result in a diagnostic. An intermediate change to STT_NOTYPE will silence
7426 Note: Some targets support extra types in addition to those listed above.
7432 @section @code{.uleb128 @var{expressions}}
7434 @cindex @code{uleb128} directive
7435 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
7436 compact, variable length representation of numbers used by the DWARF
7437 symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}.
7441 @section @code{.val @var{addr}}
7443 @cindex @code{val} directive
7444 @cindex COFF value attribute
7445 @cindex value attribute, COFF
7446 This directive, permitted only within @code{.def}/@code{.endef} pairs,
7447 records the address @var{addr} as the value attribute of a symbol table
7453 @section @code{.version "@var{string}"}
7455 @cindex @code{version} directive
7456 This directive creates a @code{.note} section and places into it an ELF
7457 formatted note of type NT_VERSION. The note's name is set to @code{string}.
7462 @section @code{.vtable_entry @var{table}, @var{offset}}
7464 @cindex @code{vtable_entry} directive
7465 This directive finds or creates a symbol @code{table} and creates a
7466 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
7469 @section @code{.vtable_inherit @var{child}, @var{parent}}
7471 @cindex @code{vtable_inherit} directive
7472 This directive finds the symbol @code{child} and finds or creates the symbol
7473 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
7474 parent whose addend is the value of the child symbol. As a special case the
7475 parent name of @code{0} is treated as referring to the @code{*ABS*} section.
7479 @section @code{.warning "@var{string}"}
7480 @cindex warning directive
7481 Similar to the directive @code{.error}
7482 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
7485 @section @code{.weak @var{names}}
7487 @cindex @code{weak} directive
7488 This directive sets the weak attribute on the comma separated list of symbol
7489 @code{names}. If the symbols do not already exist, they will be created.
7491 On COFF targets other than PE, weak symbols are a GNU extension. This
7492 directive sets the weak attribute on the comma separated list of symbol
7493 @code{names}. If the symbols do not already exist, they will be created.
7495 On the PE target, weak symbols are supported natively as weak aliases.
7496 When a weak symbol is created that is not an alias, GAS creates an
7497 alternate symbol to hold the default value.
7500 @section @code{.weakref @var{alias}, @var{target}}
7502 @cindex @code{weakref} directive
7503 This directive creates an alias to the target symbol that enables the symbol to
7504 be referenced with weak-symbol semantics, but without actually making it weak.
7505 If direct references or definitions of the symbol are present, then the symbol
7506 will not be weak, but if all references to it are through weak references, the
7507 symbol will be marked as weak in the symbol table.
7509 The effect is equivalent to moving all references to the alias to a separate
7510 assembly source file, renaming the alias to the symbol in it, declaring the
7511 symbol as weak there, and running a reloadable link to merge the object files
7512 resulting from the assembly of the new source file and the old source file that
7513 had the references to the alias removed.
7515 The alias itself never makes to the symbol table, and is entirely handled
7516 within the assembler.
7519 @section @code{.word @var{expressions}}
7521 @cindex @code{word} directive
7522 This directive expects zero or more @var{expressions}, of any section,
7523 separated by commas.
7526 For each expression, @command{@value{AS}} emits a 32-bit number.
7529 For each expression, @command{@value{AS}} emits a 16-bit number.
7534 The size of the number emitted, and its byte order,
7535 depend on what target computer the assembly is for.
7538 @c on sparc the "special treatment to support compilers" doesn't
7539 @c happen---32-bit addressability, period; no long/short jumps.
7540 @ifset DIFF-TBL-KLUGE
7541 @cindex difference tables altered
7542 @cindex altered difference tables
7544 @emph{Warning: Special Treatment to support Compilers}
7548 Machines with a 32-bit address space, but that do less than 32-bit
7549 addressing, require the following special treatment. If the machine of
7550 interest to you does 32-bit addressing (or doesn't require it;
7551 @pxref{Machine Dependencies}), you can ignore this issue.
7554 In order to assemble compiler output into something that works,
7555 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
7556 Directives of the form @samp{.word sym1-sym2} are often emitted by
7557 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
7558 directive of the form @samp{.word sym1-sym2}, and the difference between
7559 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
7560 creates a @dfn{secondary jump table}, immediately before the next label.
7561 This secondary jump table is preceded by a short-jump to the
7562 first byte after the secondary table. This short-jump prevents the flow
7563 of control from accidentally falling into the new table. Inside the
7564 table is a long-jump to @code{sym2}. The original @samp{.word}
7565 contains @code{sym1} minus the address of the long-jump to
7568 If there were several occurrences of @samp{.word sym1-sym2} before the
7569 secondary jump table, all of them are adjusted. If there was a
7570 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
7571 long-jump to @code{sym4} is included in the secondary jump table,
7572 and the @code{.word} directives are adjusted to contain @code{sym3}
7573 minus the address of the long-jump to @code{sym4}; and so on, for as many
7574 entries in the original jump table as necessary.
7577 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
7578 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
7579 assembly language programmers.
7582 @c end DIFF-TBL-KLUGE
7584 @ifclear no-space-dir
7586 @section @code{.zero @var{size}}
7588 @cindex @code{zero} directive
7589 @cindex filling memory with zero bytes
7590 This directive emits @var{size} 0-valued bytes. @var{size} must be an absolute
7591 expression. This directive is actually an alias for the @samp{.skip} directive
7592 so it can take an optional second argument of the value to store in the bytes
7593 instead of zero. Using @samp{.zero} in this way would be confusing however.
7597 @section @code{.2byte @var{expression} [, @var{expression}]*}
7598 @cindex @code{2byte} directive
7599 @cindex two-byte integer
7600 @cindex integer, 2-byte
7602 This directive expects zero or more expressions, separated by commas. If there
7603 are no expressions then the directive does nothing. Otherwise each expression
7604 is evaluated in turn and placed in the next two bytes of the current output
7605 section, using the endian model of the target. If an expression will not fit
7606 in two bytes, a warning message is displayed and the least significant two
7607 bytes of the expression's value are used. If an expression cannot be evaluated
7608 at assembly time then relocations will be generated in order to compute the
7611 This directive does not apply any alignment before or after inserting the
7612 values. As a result of this, if relocations are generated, they may be
7613 different from those used for inserting values with a guaranteed alignment.
7616 @section @code{.4byte @var{expression} [, @var{expression}]*}
7617 @cindex @code{4byte} directive
7618 @cindex four-byte integer
7619 @cindex integer, 4-byte
7621 Like the @option{.2byte} directive, except that it inserts unaligned, four byte
7622 long values into the output.
7625 @section @code{.8byte @var{expression} [, @var{expression}]*}
7626 @cindex @code{8byte} directive
7627 @cindex eight-byte integer
7628 @cindex integer, 8-byte
7630 Like the @option{.2byte} directive, except that it inserts unaligned, eight
7631 byte long bignum values into the output.
7634 @section Deprecated Directives
7636 @cindex deprecated directives
7637 @cindex obsolescent directives
7638 One day these directives won't work.
7639 They are included for compatibility with older assemblers.
7646 @node Object Attributes
7647 @chapter Object Attributes
7648 @cindex object attributes
7650 @command{@value{AS}} assembles source files written for a specific architecture
7651 into object files for that architecture. But not all object files are alike.
7652 Many architectures support incompatible variations. For instance, floating
7653 point arguments might be passed in floating point registers if the object file
7654 requires hardware floating point support---or floating point arguments might be
7655 passed in integer registers if the object file supports processors with no
7656 hardware floating point unit. Or, if two objects are built for different
7657 generations of the same architecture, the combination may require the
7658 newer generation at run-time.
7660 This information is useful during and after linking. At link time,
7661 @command{@value{LD}} can warn about incompatible object files. After link
7662 time, tools like @command{gdb} can use it to process the linked file
7665 Compatibility information is recorded as a series of object attributes. Each
7666 attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
7667 string, and indicates who sets the meaning of the tag. The tag is an integer,
7668 and indicates what property the attribute describes. The value may be a string
7669 or an integer, and indicates how the property affects this object. Missing
7670 attributes are the same as attributes with a zero value or empty string value.
7672 Object attributes were developed as part of the ABI for the ARM Architecture.
7673 The file format is documented in @cite{ELF for the ARM Architecture}.
7676 * GNU Object Attributes:: @sc{gnu} Object Attributes
7677 * Defining New Object Attributes:: Defining New Object Attributes
7680 @node GNU Object Attributes
7681 @section @sc{gnu} Object Attributes
7683 The @code{.gnu_attribute} directive records an object attribute
7684 with vendor @samp{gnu}.
7686 Except for @samp{Tag_compatibility}, which has both an integer and a string for
7687 its value, @sc{gnu} attributes have a string value if the tag number is odd and
7688 an integer value if the tag number is even. The second bit (@code{@var{tag} &
7689 2} is set for architecture-independent attributes and clear for
7690 architecture-dependent ones.
7692 @subsection Common @sc{gnu} attributes
7694 These attributes are valid on all architectures.
7697 @item Tag_compatibility (32)
7698 The compatibility attribute takes an integer flag value and a vendor name. If
7699 the flag value is 0, the file is compatible with other toolchains. If it is 1,
7700 then the file is only compatible with the named toolchain. If it is greater
7701 than 1, the file can only be processed by other toolchains under some private
7702 arrangement indicated by the flag value and the vendor name.
7705 @subsection M680x0 Attributes
7708 @item Tag_GNU_M68K_ABI_FP (4)
7709 The floating-point ABI used by this object file. The value will be:
7713 0 for files not affected by the floating-point ABI.
7715 1 for files using double-precision hardware floating-point ABI.
7717 2 for files using the software floating-point ABI.
7721 @subsection MIPS Attributes
7724 @item Tag_GNU_MIPS_ABI_FP (4)
7725 The floating-point ABI used by this object file. The value will be:
7729 0 for files not affected by the floating-point ABI.
7731 1 for files using the hardware floating-point ABI with a standard
7732 double-precision FPU.
7734 2 for files using the hardware floating-point ABI with a single-precision FPU.
7736 3 for files using the software floating-point ABI.
7738 4 for files using the deprecated hardware floating-point ABI which used 64-bit
7739 floating-point registers, 32-bit general-purpose registers and increased the
7740 number of callee-saved floating-point registers.
7742 5 for files using the hardware floating-point ABI with a double-precision FPU
7743 with either 32-bit or 64-bit floating-point registers and 32-bit
7744 general-purpose registers.
7746 6 for files using the hardware floating-point ABI with 64-bit floating-point
7747 registers and 32-bit general-purpose registers.
7749 7 for files using the hardware floating-point ABI with 64-bit floating-point
7750 registers, 32-bit general-purpose registers and a rule that forbids the
7751 direct use of odd-numbered single-precision floating-point registers.
7755 @subsection PowerPC Attributes
7758 @item Tag_GNU_Power_ABI_FP (4)
7759 The floating-point ABI used by this object file. The value will be:
7763 0 for files not affected by the floating-point ABI.
7765 1 for files using double-precision hardware floating-point ABI.
7767 2 for files using the software floating-point ABI.
7769 3 for files using single-precision hardware floating-point ABI.
7772 @item Tag_GNU_Power_ABI_Vector (8)
7773 The vector ABI used by this object file. The value will be:
7777 0 for files not affected by the vector ABI.
7779 1 for files using general purpose registers to pass vectors.
7781 2 for files using AltiVec registers to pass vectors.
7783 3 for files using SPE registers to pass vectors.
7787 @subsection IBM z Systems Attributes
7790 @item Tag_GNU_S390_ABI_Vector (8)
7791 The vector ABI used by this object file. The value will be:
7795 0 for files not affected by the vector ABI.
7797 1 for files using software vector ABI.
7799 2 for files using hardware vector ABI.
7803 @subsection MSP430 Attributes
7806 @item Tag_GNU_MSP430_Data_Region (4)
7807 The data region used by this object file. The value will be:
7811 0 for files not using the large memory model.
7813 1 for files which have been compiled with the condition that all
7814 data is in the lower memory region, i.e. below address 0x10000.
7816 2 for files which allow data to be placed in the full 20-bit memory range.
7820 @node Defining New Object Attributes
7821 @section Defining New Object Attributes
7823 If you want to define a new @sc{gnu} object attribute, here are the places you
7824 will need to modify. New attributes should be discussed on the @samp{binutils}
7829 This manual, which is the official register of attributes.
7831 The header for your architecture @file{include/elf}, to define the tag.
7833 The @file{bfd} support file for your architecture, to merge the attribute
7834 and issue any appropriate link warnings.
7836 Test cases in @file{ld/testsuite} for merging and link warnings.
7838 @file{binutils/readelf.c} to display your attribute.
7840 GCC, if you want the compiler to mark the attribute automatically.
7846 @node Machine Dependencies
7847 @chapter Machine Dependent Features
7849 @cindex machine dependencies
7850 The machine instruction sets are (almost by definition) different on
7851 each machine where @command{@value{AS}} runs. Floating point representations
7852 vary as well, and @command{@value{AS}} often supports a few additional
7853 directives or command-line options for compatibility with other
7854 assemblers on a particular platform. Finally, some versions of
7855 @command{@value{AS}} support special pseudo-instructions for branch
7858 This chapter discusses most of these differences, though it does not
7859 include details on any machine's instruction set. For details on that
7860 subject, see the hardware manufacturer's manual.
7864 * AArch64-Dependent:: AArch64 Dependent Features
7867 * Alpha-Dependent:: Alpha Dependent Features
7870 * ARC-Dependent:: ARC Dependent Features
7873 * ARM-Dependent:: ARM Dependent Features
7876 * AVR-Dependent:: AVR Dependent Features
7879 * Blackfin-Dependent:: Blackfin Dependent Features
7882 * BPF-Dependent:: BPF Dependent Features
7885 * CR16-Dependent:: CR16 Dependent Features
7888 * CRIS-Dependent:: CRIS Dependent Features
7891 * C-SKY-Dependent:: C-SKY Dependent Features
7894 * D10V-Dependent:: D10V Dependent Features
7897 * D30V-Dependent:: D30V Dependent Features
7900 * Epiphany-Dependent:: EPIPHANY Dependent Features
7903 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7906 * HPPA-Dependent:: HPPA Dependent Features
7909 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
7912 * IA-64-Dependent:: Intel IA-64 Dependent Features
7915 * IP2K-Dependent:: IP2K Dependent Features
7918 * LoongArch-Dependent:: LoongArch Dependent Features
7921 * LM32-Dependent:: LM32 Dependent Features
7924 * M32C-Dependent:: M32C Dependent Features
7927 * M32R-Dependent:: M32R Dependent Features
7930 * M68K-Dependent:: M680x0 Dependent Features
7933 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
7936 * S12Z-Dependent:: S12Z Dependent Features
7939 * Meta-Dependent :: Meta Dependent Features
7942 * MicroBlaze-Dependent:: MICROBLAZE Dependent Features
7945 * MIPS-Dependent:: MIPS Dependent Features
7948 * MMIX-Dependent:: MMIX Dependent Features
7951 * MSP430-Dependent:: MSP430 Dependent Features
7954 * NDS32-Dependent:: Andes NDS32 Dependent Features
7957 * NiosII-Dependent:: Altera Nios II Dependent Features
7960 * NS32K-Dependent:: NS32K Dependent Features
7963 * OpenRISC-Dependent:: OpenRISC 1000 Features
7966 * PDP-11-Dependent:: PDP-11 Dependent Features
7969 * PJ-Dependent:: picoJava Dependent Features
7972 * PPC-Dependent:: PowerPC Dependent Features
7975 * PRU-Dependent:: PRU Dependent Features
7978 * RISC-V-Dependent:: RISC-V Dependent Features
7981 * RL78-Dependent:: RL78 Dependent Features
7984 * RX-Dependent:: RX Dependent Features
7987 * S/390-Dependent:: IBM S/390 Dependent Features
7990 * SCORE-Dependent:: SCORE Dependent Features
7993 * SH-Dependent:: Renesas / SuperH SH Dependent Features
7996 * Sparc-Dependent:: SPARC Dependent Features
7999 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
8002 * TIC6X-Dependent :: TI TMS320C6x Dependent Features
8005 * TILE-Gx-Dependent :: Tilera TILE-Gx Dependent Features
8008 * TILEPro-Dependent :: Tilera TILEPro Dependent Features
8011 * V850-Dependent:: V850 Dependent Features
8014 * Vax-Dependent:: VAX Dependent Features
8017 * Visium-Dependent:: Visium Dependent Features
8020 * WebAssembly-Dependent:: WebAssembly Dependent Features
8023 * XGATE-Dependent:: XGATE Dependent Features
8026 * XSTORMY16-Dependent:: XStormy16 Dependent Features
8029 * Xtensa-Dependent:: Xtensa Dependent Features
8032 * Z80-Dependent:: Z80 Dependent Features
8035 * Z8000-Dependent:: Z8000 Dependent Features
8042 @c The following major nodes are *sections* in the GENERIC version, *chapters*
8043 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
8044 @c peculiarity: to preserve cross-references, there must be a node called
8045 @c "Machine Dependencies". Hence the conditional nodenames in each
8046 @c major node below. Node defaulting in makeinfo requires adjacency of
8047 @c node and sectioning commands; hence the repetition of @chapter BLAH
8048 @c in both conditional blocks.
8051 @include c-aarch64.texi
8055 @include c-alpha.texi
8071 @include c-bfin.texi
8079 @include c-cr16.texi
8083 @include c-cris.texi
8087 @include c-csky.texi
8092 @node Machine Dependencies
8093 @chapter Machine Dependent Features
8095 The machine instruction sets are different on each Renesas chip family,
8096 and there are also some syntax differences among the families. This
8097 chapter describes the specific @command{@value{AS}} features for each
8101 * H8/300-Dependent:: Renesas H8/300 Dependent Features
8102 * SH-Dependent:: Renesas SH Dependent Features
8109 @include c-d10v.texi
8113 @include c-d30v.texi
8117 @include c-epiphany.texi
8121 @include c-h8300.texi
8125 @include c-hppa.texi
8129 @include c-i386.texi
8133 @include c-ia64.texi
8137 @include c-ip2k.texi
8141 @include c-lm32.texi
8145 @include c-loongarch.texi
8149 @include c-m32c.texi
8153 @include c-m32r.texi
8157 @include c-m68k.texi
8161 @include c-m68hc11.texi
8165 @include c-s12z.texi
8169 @include c-metag.texi
8173 @include c-microblaze.texi
8177 @include c-mips.texi
8181 @include c-mmix.texi
8185 @include c-msp430.texi
8189 @include c-nds32.texi
8193 @include c-nios2.texi
8197 @include c-ns32k.texi
8201 @include c-or1k.texi
8205 @include c-pdp11.texi
8221 @include c-riscv.texi
8225 @include c-rl78.texi
8233 @include c-s390.texi
8237 @include c-score.texi
8245 @include c-sparc.texi
8249 @include c-tic54x.texi
8253 @include c-tic6x.texi
8257 @include c-tilegx.texi
8261 @include c-tilepro.texi
8265 @include c-v850.texi
8273 @include c-visium.texi
8277 @include c-wasm32.texi
8281 @include c-xgate.texi
8285 @include c-xstormy16.texi
8289 @include c-xtensa.texi
8301 @c reverse effect of @down at top of generic Machine-Dep chapter
8305 @node Reporting Bugs
8306 @chapter Reporting Bugs
8307 @cindex bugs in assembler
8308 @cindex reporting bugs in assembler
8310 Your bug reports play an essential role in making @command{@value{AS}} reliable.
8312 Reporting a bug may help you by bringing a solution to your problem, or it may
8313 not. But in any case the principal function of a bug report is to help the
8314 entire community by making the next version of @command{@value{AS}} work better.
8315 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
8317 In order for a bug report to serve its purpose, you must include the
8318 information that enables us to fix the bug.
8321 * Bug Criteria:: Have you found a bug?
8322 * Bug Reporting:: How to report bugs
8326 @section Have You Found a Bug?
8327 @cindex bug criteria
8329 If you are not sure whether you have found a bug, here are some guidelines:
8332 @cindex fatal signal
8333 @cindex assembler crash
8334 @cindex crash of assembler
8336 If the assembler gets a fatal signal, for any input whatever, that is a
8337 @command{@value{AS}} bug. Reliable assemblers never crash.
8339 @cindex error on valid input
8341 If @command{@value{AS}} produces an error message for valid input, that is a bug.
8343 @cindex invalid input
8345 If @command{@value{AS}} does not produce an error message for invalid input, that
8346 is a bug. However, you should note that your idea of ``invalid input'' might
8347 be our idea of ``an extension'' or ``support for traditional practice''.
8350 If you are an experienced user of assemblers, your suggestions for improvement
8351 of @command{@value{AS}} are welcome in any case.
8355 @section How to Report Bugs
8357 @cindex assembler bugs, reporting
8359 A number of companies and individuals offer support for @sc{gnu} products. If
8360 you obtained @command{@value{AS}} from a support organization, we recommend you
8361 contact that organization first.
8363 You can find contact information for many support companies and
8364 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
8368 In any event, we also recommend that you send bug reports for @command{@value{AS}}
8372 The fundamental principle of reporting bugs usefully is this:
8373 @strong{report all the facts}. If you are not sure whether to state a
8374 fact or leave it out, state it!
8376 Often people omit facts because they think they know what causes the problem
8377 and assume that some details do not matter. Thus, you might assume that the
8378 name of a symbol you use in an example does not matter. Well, probably it does
8379 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
8380 happens to fetch from the location where that name is stored in memory;
8381 perhaps, if the name were different, the contents of that location would fool
8382 the assembler into doing the right thing despite the bug. Play it safe and
8383 give a specific, complete example. That is the easiest thing for you to do,
8384 and the most helpful.
8386 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
8387 it is new to us. Therefore, always write your bug reports on the assumption
8388 that the bug has not been reported previously.
8390 Sometimes people give a few sketchy facts and ask, ``Does this ring a
8391 bell?'' This cannot help us fix a bug, so it is basically useless. We
8392 respond by asking for enough details to enable us to investigate.
8393 You might as well expedite matters by sending them to begin with.
8395 To enable us to fix the bug, you should include all these things:
8399 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
8400 it with the @samp{--version} argument.
8402 Without this, we will not know whether there is any point in looking for
8403 the bug in the current version of @command{@value{AS}}.
8406 Any patches you may have applied to the @command{@value{AS}} source.
8409 The type of machine you are using, and the operating system name and
8413 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
8417 The command arguments you gave the assembler to assemble your example and
8418 observe the bug. To guarantee you will not omit something important, list them
8419 all. A copy of the Makefile (or the output from make) is sufficient.
8421 If we were to try to guess the arguments, we would probably guess wrong
8422 and then we might not encounter the bug.
8425 A complete input file that will reproduce the bug. If the bug is observed when
8426 the assembler is invoked via a compiler, send the assembler source, not the
8427 high level language source. Most compilers will produce the assembler source
8428 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
8429 the options @samp{-v --save-temps}; this will save the assembler source in a
8430 file with an extension of @file{.s}, and also show you exactly how
8431 @command{@value{AS}} is being run.
8434 A description of what behavior you observe that you believe is
8435 incorrect. For example, ``It gets a fatal signal.''
8437 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
8438 will certainly notice it. But if the bug is incorrect output, we might not
8439 notice unless it is glaringly wrong. You might as well not give us a chance to
8442 Even if the problem you experience is a fatal signal, you should still say so
8443 explicitly. Suppose something strange is going on, such as, your copy of
8444 @command{@value{AS}} is out of sync, or you have encountered a bug in the C
8445 library on your system. (This has happened!) Your copy might crash and ours
8446 would not. If you told us to expect a crash, then when ours fails to crash, we
8447 would know that the bug was not happening for us. If you had not told us to
8448 expect a crash, then we would not be able to draw any conclusion from our
8452 If you wish to suggest changes to the @command{@value{AS}} source, send us context
8453 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
8454 option. Always send diffs from the old file to the new file. If you even
8455 discuss something in the @command{@value{AS}} source, refer to it by context, not
8458 The line numbers in our development sources will not match those in your
8459 sources. Your line numbers would convey no useful information to us.
8462 Here are some things that are not necessary:
8466 A description of the envelope of the bug.
8468 Often people who encounter a bug spend a lot of time investigating
8469 which changes to the input file will make the bug go away and which
8470 changes will not affect it.
8472 This is often time consuming and not very useful, because the way we
8473 will find the bug is by running a single example under the debugger
8474 with breakpoints, not by pure deduction from a series of examples.
8475 We recommend that you save your time for something else.
8477 Of course, if you can find a simpler example to report @emph{instead}
8478 of the original one, that is a convenience for us. Errors in the
8479 output will be easier to spot, running under the debugger will take
8480 less time, and so on.
8482 However, simplification is not vital; if you do not want to do this,
8483 report the bug anyway and send us the entire test case you used.
8486 A patch for the bug.
8488 A patch for the bug does help us if it is a good one. But do not omit
8489 the necessary information, such as the test case, on the assumption that
8490 a patch is all we need. We might see problems with your patch and decide
8491 to fix the problem another way, or we might not understand it at all.
8493 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
8494 construct an example that will make the program follow a certain path through
8495 the code. If you do not send us the example, we will not be able to construct
8496 one, so we will not be able to verify that the bug is fixed.
8498 And if we cannot understand what bug you are trying to fix, or why your
8499 patch should be an improvement, we will not install it. A test case will
8500 help us to understand.
8503 A guess about what the bug is or what it depends on.
8505 Such guesses are usually wrong. Even we cannot guess right about such
8506 things without first using the debugger to find the facts.
8509 @node Acknowledgements
8510 @chapter Acknowledgements
8512 If you have contributed to GAS and your name isn't listed here,
8513 it is not meant as a slight. We just don't know about it. Send mail to the
8514 maintainer, and we'll correct the situation. Currently
8516 the maintainer is Nick Clifton (email address @code{nickc@@redhat.com}).
8518 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
8521 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
8522 information and the 68k series machines, most of the preprocessing pass, and
8523 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
8525 K. Richard Pixley maintained GAS for a while, adding various enhancements and
8526 many bug fixes, including merging support for several processors, breaking GAS
8527 up to handle multiple object file format back ends (including heavy rewrite,
8528 testing, an integration of the coff and b.out back ends), adding configuration
8529 including heavy testing and verification of cross assemblers and file splits
8530 and renaming, converted GAS to strictly ANSI C including full prototypes, added
8531 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
8532 port (including considerable amounts of reverse engineering), a SPARC opcode
8533 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
8534 assertions and made them work, much other reorganization, cleanup, and lint.
8536 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
8537 in format-specific I/O modules.
8539 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
8540 has done much work with it since.
8542 The Intel 80386 machine description was written by Eliot Dresselhaus.
8544 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
8546 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
8547 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
8549 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
8550 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
8551 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
8552 support a.out format.
8554 Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
8555 tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
8556 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
8557 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
8560 John Gilmore built the AMD 29000 support, added @code{.include} support, and
8561 simplified the configuration of which versions accept which directives. He
8562 updated the 68k machine description so that Motorola's opcodes always produced
8563 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
8564 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
8565 cross-compilation support, and one bug in relaxation that took a week and
8566 required the proverbial one-bit fix.
8568 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
8569 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
8570 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
8571 PowerPC assembler, and made a few other minor patches.
8573 Steve Chamberlain made GAS able to generate listings.
8575 Hewlett-Packard contributed support for the HP9000/300.
8577 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
8578 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
8579 formats). This work was supported by both the Center for Software Science at
8580 the University of Utah and Cygnus Support.
8582 Support for ELF format files has been worked on by Mark Eichin of Cygnus
8583 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
8584 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
8585 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
8586 and some initial 64-bit support).
8588 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
8590 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
8591 support for openVMS/Alpha.
8593 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
8596 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
8597 Inc.@: added support for Xtensa processors.
8599 Several engineers at Cygnus Support have also provided many small bug fixes and
8600 configuration enhancements.
8602 Jon Beniston added support for the Lattice Mico32 architecture.
8604 Many others have contributed large or small bugfixes and enhancements. If
8605 you have contributed significant work and are not mentioned on this list, and
8606 want to be, let us know. Some of the history has been lost; we are not
8607 intentionally leaving anyone out.
8609 @node GNU Free Documentation License
8610 @appendix GNU Free Documentation License
8614 @unnumbered AS Index