1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright (C) 1991-2015 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{} 1991-2015 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{} 1991-2015 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-2}] [@b{--gdwarf-sections}]
234 [@b{--help}] [@b{-I} @var{dir}] [@b{-J}]
235 [@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}]
236 [@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}]
237 [@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}] [@b{-o}
238 @var{objfile}] [@b{-R}] [@b{--reduce-memory-overheads}] [@b{--statistics}]
239 [@b{-v}] [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}]
240 [@b{--fatal-warnings}] [@b{-w}] [@b{-x}] [@b{-Z}] [@b{@@@var{FILE}}]
241 [@b{--sectname-subst}] [@b{--size-check=[error|warning]}]
242 [@b{--target-help}] [@var{target-options}]
243 [@b{--}|@var{files} @dots{}]
245 @c Target dependent options are listed below. Keep the list sorted.
246 @c Add an empty line for separation.
249 @emph{Target AArch64 options:}
251 [@b{-mabi}=@var{ABI}]
255 @emph{Target Alpha options:}
257 [@b{-mdebug} | @b{-no-mdebug}]
258 [@b{-replace} | @b{-noreplace}]
259 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
260 [@b{-F}] [@b{-32addr}]
264 @emph{Target ARC options:}
270 @emph{Target ARM options:}
271 @c Don't document the deprecated options
272 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
273 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
274 [@b{-mfpu}=@var{floating-point-format}]
275 [@b{-mfloat-abi}=@var{abi}]
276 [@b{-meabi}=@var{ver}]
279 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
280 @b{-mapcs-reentrant}]
281 [@b{-mthumb-interwork}] [@b{-k}]
285 @emph{Target Blackfin options:}
286 [@b{-mcpu}=@var{processor}[-@var{sirevision}]]
293 @emph{Target CRIS options:}
294 [@b{--underscore} | @b{--no-underscore}]
296 [@b{--emulation=criself} | @b{--emulation=crisaout}]
297 [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}]
298 @c Deprecated -- deliberately not documented.
303 @emph{Target D10V options:}
308 @emph{Target D30V options:}
309 [@b{-O}|@b{-n}|@b{-N}]
313 @emph{Target EPIPHANY options:}
314 [@b{-mepiphany}|@b{-mepiphany16}]
318 @emph{Target H8/300 options:}
322 @c HPPA has no machine-dependent assembler options (yet).
326 @emph{Target i386 options:}
327 [@b{--32}|@b{--x32}|@b{--64}] [@b{-n}]
328 [@b{-march}=@var{CPU}[+@var{EXTENSION}@dots{}]] [@b{-mtune}=@var{CPU}]
332 @emph{Target i960 options:}
333 @c see md_parse_option in tc-i960.c
334 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
336 [@b{-b}] [@b{-no-relax}]
340 @emph{Target IA-64 options:}
341 [@b{-mconstant-gp}|@b{-mauto-pic}]
342 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
344 [@b{-mtune=itanium1}|@b{-mtune=itanium2}]
345 [@b{-munwind-check=warning}|@b{-munwind-check=error}]
346 [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}]
347 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
351 @emph{Target IP2K options:}
352 [@b{-mip2022}|@b{-mip2022ext}]
356 @emph{Target M32C options:}
357 [@b{-m32c}|@b{-m16c}] [-relax] [-h-tick-hex]
361 @emph{Target M32R options:}
362 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
367 @emph{Target M680X0 options:}
368 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
372 @emph{Target M68HC11 options:}
373 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}|@b{-mm9s12x}|@b{-mm9s12xg}]
374 [@b{-mshort}|@b{-mlong}]
375 [@b{-mshort-double}|@b{-mlong-double}]
376 [@b{--force-long-branches}] [@b{--short-branches}]
377 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
378 [@b{--print-opcodes}] [@b{--generate-example}]
382 @emph{Target MCORE options:}
383 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
384 [@b{-mcpu=[210|340]}]
388 @emph{Target Meta options:}
389 [@b{-mcpu=@var{cpu}}] [@b{-mfpu=@var{cpu}}] [@b{-mdsp=@var{cpu}}]
392 @emph{Target MICROBLAZE options:}
393 @c MicroBlaze has no machine-dependent assembler options.
397 @emph{Target MIPS options:}
398 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
399 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
400 [@b{-non_shared}] [@b{-xgot} [@b{-mvxworks-pic}]
401 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
402 [@b{-mfp64}] [@b{-mgp64}] [@b{-mfpxx}]
403 [@b{-modd-spreg}] [@b{-mno-odd-spreg}]
404 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
405 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
406 [@b{-mips32r3}] [@b{-mips32r5}] [@b{-mips32r6}] [@b{-mips64}] [@b{-mips64r2}]
407 [@b{-mips64r3}] [@b{-mips64r5}] [@b{-mips64r6}]
408 [@b{-construct-floats}] [@b{-no-construct-floats}]
409 [@b{-mnan=@var{encoding}}]
410 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
411 [@b{-mips16}] [@b{-no-mips16}]
412 [@b{-mmicromips}] [@b{-mno-micromips}]
413 [@b{-msmartmips}] [@b{-mno-smartmips}]
414 [@b{-mips3d}] [@b{-no-mips3d}]
415 [@b{-mdmx}] [@b{-no-mdmx}]
416 [@b{-mdsp}] [@b{-mno-dsp}]
417 [@b{-mdspr2}] [@b{-mno-dspr2}]
418 [@b{-mmsa}] [@b{-mno-msa}]
419 [@b{-mxpa}] [@b{-mno-xpa}]
420 [@b{-mmt}] [@b{-mno-mt}]
421 [@b{-mmcu}] [@b{-mno-mcu}]
422 [@b{-minsn32}] [@b{-mno-insn32}]
423 [@b{-mfix7000}] [@b{-mno-fix7000}]
424 [@b{-mfix-rm7000}] [@b{-mno-fix-rm7000}]
425 [@b{-mfix-vr4120}] [@b{-mno-fix-vr4120}]
426 [@b{-mfix-vr4130}] [@b{-mno-fix-vr4130}]
427 [@b{-mdebug}] [@b{-no-mdebug}]
428 [@b{-mpdr}] [@b{-mno-pdr}]
432 @emph{Target MMIX options:}
433 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
434 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
435 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
436 [@b{--linker-allocated-gregs}]
440 @emph{Target Nios II options:}
441 [@b{-relax-all}] [@b{-relax-section}] [@b{-no-relax}]
446 @emph{Target NDS32 options:}
447 [@b{-EL}] [@b{-EB}] [@b{-O}] [@b{-Os}] [@b{-mcpu=@var{cpu}}]
448 [@b{-misa=@var{isa}}] [@b{-mabi=@var{abi}}] [@b{-mall-ext}]
449 [@b{-m[no-]16-bit}] [@b{-m[no-]perf-ext}] [@b{-m[no-]perf2-ext}]
450 [@b{-m[no-]string-ext}] [@b{-m[no-]dsp-ext}] [@b{-m[no-]mac}] [@b{-m[no-]div}]
451 [@b{-m[no-]audio-isa-ext}] [@b{-m[no-]fpu-sp-ext}] [@b{-m[no-]fpu-dp-ext}]
452 [@b{-m[no-]fpu-fma}] [@b{-mfpu-freg=@var{FREG}}] [@b{-mreduced-regs}]
453 [@b{-mfull-regs}] [@b{-m[no-]dx-regs}] [@b{-mpic}] [@b{-mno-relax}]
458 @emph{Target PDP11 options:}
459 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
460 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
461 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
465 @emph{Target picoJava options:}
470 @emph{Target PowerPC options:}
472 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|@b{-m403}|@b{-m405}|
473 @b{-m440}|@b{-m464}|@b{-m476}|@b{-m7400}|@b{-m7410}|@b{-m7450}|@b{-m7455}|@b{-m750cl}|@b{-mppc64}|
474 @b{-m620}|@b{-me500}|@b{-e500x2}|@b{-me500mc}|@b{-me500mc64}|@b{-me5500}|@b{-me6500}|@b{-mppc64bridge}|
475 @b{-mbooke}|@b{-mpower4}|@b{-mpwr4}|@b{-mpower5}|@b{-mpwr5}|@b{-mpwr5x}|@b{-mpower6}|@b{-mpwr6}|
476 @b{-mpower7}|@b{-mpwr7}|@b{-mpower8}|@b{-mpwr8}|@b{-ma2}|@b{-mcell}|@b{-mspe}|@b{-mtitan}|@b{-me300}|@b{-mcom}]
477 [@b{-many}] [@b{-maltivec}|@b{-mvsx}|@b{-mhtm}|@b{-mvle}]
478 [@b{-mregnames}|@b{-mno-regnames}]
479 [@b{-mrelocatable}|@b{-mrelocatable-lib}|@b{-K PIC}] [@b{-memb}]
480 [@b{-mlittle}|@b{-mlittle-endian}|@b{-le}|@b{-mbig}|@b{-mbig-endian}|@b{-be}]
481 [@b{-msolaris}|@b{-mno-solaris}]
482 [@b{-nops=@var{count}}]
486 @emph{Target RL78 options:}
488 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
492 @emph{Target RX options:}
493 [@b{-mlittle-endian}|@b{-mbig-endian}]
494 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
495 [@b{-muse-conventional-section-names}]
496 [@b{-msmall-data-limit}]
499 [@b{-mint-register=@var{number}}]
500 [@b{-mgcc-abi}|@b{-mrx-abi}]
504 @emph{Target s390 options:}
505 [@b{-m31}|@b{-m64}] [@b{-mesa}|@b{-mzarch}] [@b{-march}=@var{CPU}]
506 [@b{-mregnames}|@b{-mno-regnames}]
507 [@b{-mwarn-areg-zero}]
511 @emph{Target SCORE options:}
512 [@b{-EB}][@b{-EL}][@b{-FIXDD}][@b{-NWARN}]
513 [@b{-SCORE5}][@b{-SCORE5U}][@b{-SCORE7}][@b{-SCORE3}]
514 [@b{-march=score7}][@b{-march=score3}]
515 [@b{-USE_R1}][@b{-KPIC}][@b{-O0}][@b{-G} @var{num}][@b{-V}]
519 @emph{Target SPARC options:}
520 @c The order here is important. See c-sparc.texi.
521 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
522 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
523 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
528 @emph{Target TIC54X options:}
529 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
530 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
534 @emph{Target TIC6X options:}
535 [@b{-march=@var{arch}}] [@b{-mbig-endian}|@b{-mlittle-endian}]
536 [@b{-mdsbt}|@b{-mno-dsbt}] [@b{-mpid=no}|@b{-mpid=near}|@b{-mpid=far}]
537 [@b{-mpic}|@b{-mno-pic}]
541 @emph{Target TILE-Gx options:}
542 [@b{-m32}|@b{-m64}][@b{-EB}][@b{-EL}]
545 @c TILEPro has no machine-dependent assembler options
549 @emph{Target Visium options:}
550 [@b{-mtune=@var{arch}}]
554 @emph{Target Xtensa options:}
555 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
556 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
557 [@b{--[no-]transform}]
558 [@b{--rename-section} @var{oldname}=@var{newname}]
559 [@b{--[no-]trampolines}]
563 @emph{Target Z80 options:}
564 [@b{-z80}] [@b{-r800}]
565 [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}]
566 [@b{ -ignore-unportable-instructions}] [@b{-Wnup}]
567 [@b{ -warn-undocumented-instructions}] [@b{-Wud}]
568 [@b{ -warn-unportable-instructions}] [@b{-Wup}]
569 [@b{ -forbid-undocumented-instructions}] [@b{-Fud}]
570 [@b{ -forbid-unportable-instructions}] [@b{-Fup}]
574 @c Z8000 has no machine-dependent assembler options
583 @include at-file.texi
586 Turn on listings, in any of a variety of ways:
590 omit false conditionals
593 omit debugging directives
596 include general information, like @value{AS} version and options passed
599 include high-level source
605 include macro expansions
608 omit forms processing
614 set the name of the listing file
617 You may combine these options; for example, use @samp{-aln} for assembly
618 listing without forms processing. The @samp{=file} option, if used, must be
619 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
622 Begin in alternate macro mode.
624 @xref{Altmacro,,@code{.altmacro}}.
627 @item --compress-debug-sections
628 Compress DWARF debug sections using zlib with SHF_COMPRESSED from the
629 ELF ABI. The resulting object file may not be compatible with older
630 linkers and object file utilities. Note if compression would make a
631 given section @emph{larger} then it is not compressed.
634 @cindex @samp{--compress-debug-sections=} option
635 @item --compress-debug-sections=none
636 @itemx --compress-debug-sections=zlib
637 @itemx --compress-debug-sections=zlib-gnu
638 @itemx --compress-debug-sections=zlib-gabi
639 These options control how DWARF debug sections are compressed.
640 @option{--compress-debug-sections=none} is equivalent to
641 @option{--nocompress-debug-sections}.
642 @option{--compress-debug-sections=zlib} and
643 @option{--compress-debug-sections=zlib-gabi} are equivalent to
644 @option{--compress-debug-sections}.
645 @option{--compress-debug-sections=zlib-gnu} compresses DWARF debug
646 sections using zlib. The debug sections are renamed to begin with
647 @samp{.zdebug}. Note if compression would make a given section
648 @emph{larger} then it is not compressed nor renamed.
652 @item --nocompress-debug-sections
653 Do not compress DWARF debug sections. This is the default.
656 Ignored. This option is accepted for script compatibility with calls to
659 @item --debug-prefix-map @var{old}=@var{new}
660 When assembling files in directory @file{@var{old}}, record debugging
661 information describing them as in @file{@var{new}} instead.
663 @item --defsym @var{sym}=@var{value}
664 Define the symbol @var{sym} to be @var{value} before assembling the input file.
665 @var{value} must be an integer constant. As in C, a leading @samp{0x}
666 indicates a hexadecimal value, and a leading @samp{0} indicates an octal
667 value. The value of the symbol can be overridden inside a source file via the
668 use of a @code{.set} pseudo-op.
671 ``fast''---skip whitespace and comment preprocessing (assume source is
676 Generate debugging information for each assembler source line using whichever
677 debug format is preferred by the target. This currently means either STABS,
681 Generate stabs debugging information for each assembler line. This
682 may help debugging assembler code, if the debugger can handle it.
685 Generate stabs debugging information for each assembler line, with GNU
686 extensions that probably only gdb can handle, and that could make other
687 debuggers crash or refuse to read your program. This
688 may help debugging assembler code. Currently the only GNU extension is
689 the location of the current working directory at assembling time.
692 Generate DWARF2 debugging information for each assembler line. This
693 may help debugging assembler code, if the debugger can handle it. Note---this
694 option is only supported by some targets, not all of them.
696 @item --gdwarf-sections
697 Instead of creating a .debug_line section, create a series of
698 .debug_line.@var{foo} sections where @var{foo} is the name of the
699 corresponding code section. For example a code section called @var{.text.func}
700 will have its dwarf line number information placed into a section called
701 @var{.debug_line.text.func}. If the code section is just called @var{.text}
702 then debug line section will still be called just @var{.debug_line} without any
705 @item --size-check=error
706 @itemx --size-check=warning
707 Issue an error or warning for invalid ELF .size directive.
710 Print a summary of the command line options and exit.
713 Print a summary of all target specific options and exit.
716 Add directory @var{dir} to the search list for @code{.include} directives.
719 Don't warn about signed overflow.
722 @ifclear DIFF-TBL-KLUGE
723 This option is accepted but has no effect on the @value{TARGET} family.
725 @ifset DIFF-TBL-KLUGE
726 Issue warnings when difference tables altered for long displacements.
731 Keep (in the symbol table) local symbols. These symbols start with
732 system-specific local label prefixes, typically @samp{.L} for ELF systems
733 or @samp{L} for traditional a.out systems.
738 @item --listing-lhs-width=@var{number}
739 Set the maximum width, in words, of the output data column for an assembler
740 listing to @var{number}.
742 @item --listing-lhs-width2=@var{number}
743 Set the maximum width, in words, of the output data column for continuation
744 lines in an assembler listing to @var{number}.
746 @item --listing-rhs-width=@var{number}
747 Set the maximum width of an input source line, as displayed in a listing, to
750 @item --listing-cont-lines=@var{number}
751 Set the maximum number of lines printed in a listing for a single line of input
754 @item -o @var{objfile}
755 Name the object-file output from @command{@value{AS}} @var{objfile}.
758 Fold the data section into the text section.
760 @kindex --hash-size=@var{number}
761 Set the default size of GAS's hash tables to a prime number close to
762 @var{number}. Increasing this value can reduce the length of time it takes the
763 assembler to perform its tasks, at the expense of increasing the assembler's
764 memory requirements. Similarly reducing this value can reduce the memory
765 requirements at the expense of speed.
767 @item --reduce-memory-overheads
768 This option reduces GAS's memory requirements, at the expense of making the
769 assembly processes slower. Currently this switch is a synonym for
770 @samp{--hash-size=4051}, but in the future it may have other effects as well.
773 @item --sectname-subst
774 Honor substitution sequences in section names.
776 @xref{Section Name Substitutions,,@code{.section @var{name}}}.
781 Print the maximum space (in bytes) and total time (in seconds) used by
784 @item --strip-local-absolute
785 Remove local absolute symbols from the outgoing symbol table.
789 Print the @command{as} version.
792 Print the @command{as} version and exit.
796 Suppress warning messages.
798 @item --fatal-warnings
799 Treat warnings as errors.
802 Don't suppress warning messages or treat them as errors.
811 Generate an object file even after errors.
813 @item -- | @var{files} @dots{}
814 Standard input, or source files to assemble.
822 @xref{AArch64 Options}, for the options available when @value{AS} is configured
823 for the 64-bit mode of the ARM Architecture (AArch64).
828 The following options are available when @value{AS} is configured for the
829 64-bit mode of the ARM Architecture (AArch64).
832 @include c-aarch64.texi
833 @c ended inside the included file
841 @xref{Alpha Options}, for the options available when @value{AS} is configured
842 for an Alpha processor.
847 The following options are available when @value{AS} is configured for an Alpha
851 @include c-alpha.texi
852 @c ended inside the included file
859 The following options are available when @value{AS} is configured for
864 This option selects the core processor variant.
866 Select either big-endian (-EB) or little-endian (-EL) output.
871 The following options are available when @value{AS} is configured for the ARM
875 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
876 Specify which ARM processor variant is the target.
877 @item -march=@var{architecture}[+@var{extension}@dots{}]
878 Specify which ARM architecture variant is used by the target.
879 @item -mfpu=@var{floating-point-format}
880 Select which Floating Point architecture is the target.
881 @item -mfloat-abi=@var{abi}
882 Select which floating point ABI is in use.
884 Enable Thumb only instruction decoding.
885 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
886 Select which procedure calling convention is in use.
888 Select either big-endian (-EB) or little-endian (-EL) output.
889 @item -mthumb-interwork
890 Specify that the code has been generated with interworking between Thumb and
893 Turns on CodeComposer Studio assembly syntax compatibility mode.
895 Specify that PIC code has been generated.
903 @xref{Blackfin Options}, for the options available when @value{AS} is
904 configured for the Blackfin processor family.
909 The following options are available when @value{AS} is configured for
910 the Blackfin processor family.
914 @c ended inside the included file
921 See the info pages for documentation of the CRIS-specific options.
925 The following options are available when @value{AS} is configured for
928 @cindex D10V optimization
929 @cindex optimization, D10V
931 Optimize output by parallelizing instructions.
936 The following options are available when @value{AS} is configured for a D30V
939 @cindex D30V optimization
940 @cindex optimization, D30V
942 Optimize output by parallelizing instructions.
946 Warn when nops are generated.
948 @cindex D30V nops after 32-bit multiply
950 Warn when a nop after a 32-bit multiply instruction is generated.
956 The following options are available when @value{AS} is configured for the
957 Adapteva EPIPHANY series.
960 @xref{Epiphany Options}, for the options available when @value{AS} is
961 configured for an Epiphany processor.
966 The following options are available when @value{AS} is configured for
967 an Epiphany processor.
970 @include c-epiphany.texi
971 @c ended inside the included file
979 @xref{H8/300 Options}, for the options available when @value{AS} is configured
980 for an H8/300 processor.
985 The following options are available when @value{AS} is configured for an H8/300
989 @include c-h8300.texi
990 @c ended inside the included file
998 @xref{i386-Options}, for the options available when @value{AS} is
999 configured for an i386 processor.
1003 @c man begin OPTIONS
1004 The following options are available when @value{AS} is configured for
1007 @c man begin INCLUDE
1008 @include c-i386.texi
1009 @c ended inside the included file
1014 @c man begin OPTIONS
1016 The following options are available when @value{AS} is configured for the
1017 Intel 80960 processor.
1020 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
1021 Specify which variant of the 960 architecture is the target.
1024 Add code to collect statistics about branches taken.
1027 Do not alter compare-and-branch instructions for long displacements;
1034 The following options are available when @value{AS} is configured for the
1040 Specifies that the extended IP2022 instructions are allowed.
1043 Restores the default behaviour, which restricts the permitted instructions to
1044 just the basic IP2022 ones.
1050 The following options are available when @value{AS} is configured for the
1051 Renesas M32C and M16C processors.
1056 Assemble M32C instructions.
1059 Assemble M16C instructions (the default).
1062 Enable support for link-time relaxations.
1065 Support H'00 style hex constants in addition to 0x00 style.
1071 The following options are available when @value{AS} is configured for the
1072 Renesas M32R (formerly Mitsubishi M32R) series.
1077 Specify which processor in the M32R family is the target. The default
1078 is normally the M32R, but this option changes it to the M32RX.
1080 @item --warn-explicit-parallel-conflicts or --Wp
1081 Produce warning messages when questionable parallel constructs are
1084 @item --no-warn-explicit-parallel-conflicts or --Wnp
1085 Do not produce warning messages when questionable parallel constructs are
1092 The following options are available when @value{AS} is configured for the
1093 Motorola 68000 series.
1098 Shorten references to undefined symbols, to one word instead of two.
1100 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
1101 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
1102 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
1103 Specify what processor in the 68000 family is the target. The default
1104 is normally the 68020, but this can be changed at configuration time.
1106 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
1107 The target machine does (or does not) have a floating-point coprocessor.
1108 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
1109 the basic 68000 is not compatible with the 68881, a combination of the
1110 two can be specified, since it's possible to do emulation of the
1111 coprocessor instructions with the main processor.
1113 @item -m68851 | -mno-68851
1114 The target machine does (or does not) have a memory-management
1115 unit coprocessor. The default is to assume an MMU for 68020 and up.
1123 @xref{Nios II Options}, for the options available when @value{AS} is configured
1124 for an Altera Nios II processor.
1128 @c man begin OPTIONS
1129 The following options are available when @value{AS} is configured for an
1130 Altera Nios II processor.
1132 @c man begin INCLUDE
1133 @include c-nios2.texi
1134 @c ended inside the included file
1140 For details about the PDP-11 machine dependent features options,
1141 see @ref{PDP-11-Options}.
1144 @item -mpic | -mno-pic
1145 Generate position-independent (or position-dependent) code. The
1146 default is @option{-mpic}.
1149 @itemx -mall-extensions
1150 Enable all instruction set extensions. This is the default.
1152 @item -mno-extensions
1153 Disable all instruction set extensions.
1155 @item -m@var{extension} | -mno-@var{extension}
1156 Enable (or disable) a particular instruction set extension.
1159 Enable the instruction set extensions supported by a particular CPU, and
1160 disable all other extensions.
1162 @item -m@var{machine}
1163 Enable the instruction set extensions supported by a particular machine
1164 model, and disable all other extensions.
1170 The following options are available when @value{AS} is configured for
1171 a picoJava processor.
1175 @cindex PJ endianness
1176 @cindex endianness, PJ
1177 @cindex big endian output, PJ
1179 Generate ``big endian'' format output.
1181 @cindex little endian output, PJ
1183 Generate ``little endian'' format output.
1189 The following options are available when @value{AS} is configured for the
1190 Motorola 68HC11 or 68HC12 series.
1194 @item -m68hc11 | -m68hc12 | -m68hcs12 | -mm9s12x | -mm9s12xg
1195 Specify what processor is the target. The default is
1196 defined by the configuration option when building the assembler.
1198 @item --xgate-ramoffset
1199 Instruct the linker to offset RAM addresses from S12X address space into
1200 XGATE address space.
1203 Specify to use the 16-bit integer ABI.
1206 Specify to use the 32-bit integer ABI.
1208 @item -mshort-double
1209 Specify to use the 32-bit double ABI.
1212 Specify to use the 64-bit double ABI.
1214 @item --force-long-branches
1215 Relative branches are turned into absolute ones. This concerns
1216 conditional branches, unconditional branches and branches to a
1219 @item -S | --short-branches
1220 Do not turn relative branches into absolute ones
1221 when the offset is out of range.
1223 @item --strict-direct-mode
1224 Do not turn the direct addressing mode into extended addressing mode
1225 when the instruction does not support direct addressing mode.
1227 @item --print-insn-syntax
1228 Print the syntax of instruction in case of error.
1230 @item --print-opcodes
1231 Print the list of instructions with syntax and then exit.
1233 @item --generate-example
1234 Print an example of instruction for each possible instruction and then exit.
1235 This option is only useful for testing @command{@value{AS}}.
1241 The following options are available when @command{@value{AS}} is configured
1242 for the SPARC architecture:
1245 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
1246 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
1247 Explicitly select a variant of the SPARC architecture.
1249 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
1250 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
1252 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
1253 UltraSPARC extensions.
1255 @item -xarch=v8plus | -xarch=v8plusa
1256 For compatibility with the Solaris v9 assembler. These options are
1257 equivalent to -Av8plus and -Av8plusa, respectively.
1260 Warn when the assembler switches to another architecture.
1265 The following options are available when @value{AS} is configured for the 'c54x
1270 Enable extended addressing mode. All addresses and relocations will assume
1271 extended addressing (usually 23 bits).
1272 @item -mcpu=@var{CPU_VERSION}
1273 Sets the CPU version being compiled for.
1274 @item -merrors-to-file @var{FILENAME}
1275 Redirect error output to a file, for broken systems which don't support such
1276 behaviour in the shell.
1281 The following options are available when @value{AS} is configured for
1286 This option sets the largest size of an object that can be referenced
1287 implicitly with the @code{gp} register. It is only accepted for targets that
1288 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
1290 @cindex MIPS endianness
1291 @cindex endianness, MIPS
1292 @cindex big endian output, MIPS
1294 Generate ``big endian'' format output.
1296 @cindex little endian output, MIPS
1298 Generate ``little endian'' format output.
1316 Generate code for a particular MIPS Instruction Set Architecture level.
1317 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
1318 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
1319 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
1320 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips32r3},
1321 @samp{-mips32r5}, @samp{-mips32r6}, @samp{-mips64}, @samp{-mips64r2},
1322 @samp{-mips64r3}, @samp{-mips64r5}, and @samp{-mips64r6} correspond to generic
1323 MIPS V, MIPS32, MIPS32 Release 2, MIPS32 Release 3, MIPS32 Release 5, MIPS32
1324 Release 6, MIPS64, MIPS64 Release 2, MIPS64 Release 3, MIPS64 Release 5, and
1325 MIPS64 Release 6 ISA processors, respectively.
1327 @item -march=@var{cpu}
1328 Generate code for a particular MIPS CPU.
1330 @item -mtune=@var{cpu}
1331 Schedule and tune for a particular MIPS CPU.
1335 Cause nops to be inserted if the read of the destination register
1336 of an mfhi or mflo instruction occurs in the following two instructions.
1339 @itemx -mno-fix-rm7000
1340 Cause nops to be inserted if a dmult or dmultu instruction is
1341 followed by a load instruction.
1345 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
1346 section instead of the standard ELF .stabs sections.
1350 Control generation of @code{.pdr} sections.
1354 The register sizes are normally inferred from the ISA and ABI, but these
1355 flags force a certain group of registers to be treated as 32 bits wide at
1356 all times. @samp{-mgp32} controls the size of general-purpose registers
1357 and @samp{-mfp32} controls the size of floating-point registers.
1361 The register sizes are normally inferred from the ISA and ABI, but these
1362 flags force a certain group of registers to be treated as 64 bits wide at
1363 all times. @samp{-mgp64} controls the size of general-purpose registers
1364 and @samp{-mfp64} controls the size of floating-point registers.
1367 The register sizes are normally inferred from the ISA and ABI, but using
1368 this flag in combination with @samp{-mabi=32} enables an ABI variant
1369 which will operate correctly with floating-point registers which are
1373 @itemx -mno-odd-spreg
1374 Enable use of floating-point operations on odd-numbered single-precision
1375 registers when supported by the ISA. @samp{-mfpxx} implies
1376 @samp{-mno-odd-spreg}, otherwise the default is @samp{-modd-spreg}.
1380 Generate code for the MIPS 16 processor. This is equivalent to putting
1381 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
1382 turns off this option.
1385 @itemx -mno-micromips
1386 Generate code for the microMIPS processor. This is equivalent to putting
1387 @code{.set micromips} at the start of the assembly file. @samp{-mno-micromips}
1388 turns off this option. This is equivalent to putting @code{.set nomicromips}
1389 at the start of the assembly file.
1392 @itemx -mno-smartmips
1393 Enables the SmartMIPS extension to the MIPS32 instruction set. This is
1394 equivalent to putting @code{.set smartmips} at the start of the assembly file.
1395 @samp{-mno-smartmips} turns off this option.
1399 Generate code for the MIPS-3D Application Specific Extension.
1400 This tells the assembler to accept MIPS-3D instructions.
1401 @samp{-no-mips3d} turns off this option.
1405 Generate code for the MDMX Application Specific Extension.
1406 This tells the assembler to accept MDMX instructions.
1407 @samp{-no-mdmx} turns off this option.
1411 Generate code for the DSP Release 1 Application Specific Extension.
1412 This tells the assembler to accept DSP Release 1 instructions.
1413 @samp{-mno-dsp} turns off this option.
1417 Generate code for the DSP Release 2 Application Specific Extension.
1418 This option implies -mdsp.
1419 This tells the assembler to accept DSP Release 2 instructions.
1420 @samp{-mno-dspr2} turns off this option.
1424 Generate code for the MIPS SIMD Architecture Extension.
1425 This tells the assembler to accept MSA instructions.
1426 @samp{-mno-msa} turns off this option.
1430 Generate code for the MIPS eXtended Physical Address (XPA) Extension.
1431 This tells the assembler to accept XPA instructions.
1432 @samp{-mno-xpa} turns off this option.
1436 Generate code for the MT Application Specific Extension.
1437 This tells the assembler to accept MT instructions.
1438 @samp{-mno-mt} turns off this option.
1442 Generate code for the MCU Application Specific Extension.
1443 This tells the assembler to accept MCU instructions.
1444 @samp{-mno-mcu} turns off this option.
1448 Only use 32-bit instruction encodings when generating code for the
1449 microMIPS processor. This option inhibits the use of any 16-bit
1450 instructions. This is equivalent to putting @code{.set insn32} at
1451 the start of the assembly file. @samp{-mno-insn32} turns off this
1452 option. This is equivalent to putting @code{.set noinsn32} at the
1453 start of the assembly file. By default @samp{-mno-insn32} is
1454 selected, allowing all instructions to be used.
1456 @item --construct-floats
1457 @itemx --no-construct-floats
1458 The @samp{--no-construct-floats} option disables the construction of
1459 double width floating point constants by loading the two halves of the
1460 value into the two single width floating point registers that make up
1461 the double width register. By default @samp{--construct-floats} is
1462 selected, allowing construction of these floating point constants.
1464 @item --relax-branch
1465 @itemx --no-relax-branch
1466 The @samp{--relax-branch} option enables the relaxation of out-of-range
1467 branches. By default @samp{--no-relax-branch} is selected, causing any
1468 out-of-range branches to produce an error.
1470 @item -mnan=@var{encoding}
1471 Select between the IEEE 754-2008 (@option{-mnan=2008}) or the legacy
1472 (@option{-mnan=legacy}) NaN encoding format. The latter is the default.
1475 @item --emulation=@var{name}
1476 This option was formerly used to switch between ELF and ECOFF output
1477 on targets like IRIX 5 that supported both. MIPS ECOFF support was
1478 removed in GAS 2.24, so the option now serves little purpose.
1479 It is retained for backwards compatibility.
1481 The available configuration names are: @samp{mipself}, @samp{mipslelf} and
1482 @samp{mipsbelf}. Choosing @samp{mipself} now has no effect, since the output
1483 is always ELF. @samp{mipslelf} and @samp{mipsbelf} select little- and
1484 big-endian output respectively, but @samp{-EL} and @samp{-EB} are now the
1485 preferred options instead.
1488 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1495 Control how to deal with multiplication overflow and division by zero.
1496 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1497 (and only work for Instruction Set Architecture level 2 and higher);
1498 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1502 When this option is used, @command{@value{AS}} will issue a warning every
1503 time it generates a nop instruction from a macro.
1508 The following options are available when @value{AS} is configured for
1514 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1515 The command line option @samp{-nojsri2bsr} can be used to disable it.
1519 Enable or disable the silicon filter behaviour. By default this is disabled.
1520 The default can be overridden by the @samp{-sifilter} command line option.
1523 Alter jump instructions for long displacements.
1525 @item -mcpu=[210|340]
1526 Select the cpu type on the target hardware. This controls which instructions
1530 Assemble for a big endian target.
1533 Assemble for a little endian target.
1542 @xref{Meta Options}, for the options available when @value{AS} is configured
1543 for a Meta processor.
1547 @c man begin OPTIONS
1548 The following options are available when @value{AS} is configured for a
1551 @c man begin INCLUDE
1552 @include c-metag.texi
1553 @c ended inside the included file
1558 @c man begin OPTIONS
1560 See the info pages for documentation of the MMIX-specific options.
1566 @xref{NDS32 Options}, for the options available when @value{AS} is configured
1567 for a NDS32 processor.
1569 @c ended inside the included file
1573 @c man begin OPTIONS
1574 The following options are available when @value{AS} is configured for a
1577 @c man begin INCLUDE
1578 @include c-nds32.texi
1579 @c ended inside the included file
1586 @xref{PowerPC-Opts}, for the options available when @value{AS} is configured
1587 for a PowerPC processor.
1591 @c man begin OPTIONS
1592 The following options are available when @value{AS} is configured for a
1595 @c man begin INCLUDE
1597 @c ended inside the included file
1602 @c man begin OPTIONS
1604 See the info pages for documentation of the RX-specific options.
1608 The following options are available when @value{AS} is configured for the s390
1614 Select the word size, either 31/32 bits or 64 bits.
1617 Select the architecture mode, either the Enterprise System
1618 Architecture (esa) or the z/Architecture mode (zarch).
1619 @item -march=@var{processor}
1620 Specify which s390 processor variant is the target, @samp{g6}, @samp{g6},
1621 @samp{z900}, @samp{z990}, @samp{z9-109}, @samp{z9-ec}, @samp{z10},
1622 @samp{z196}, @samp{zEC12}, or @samp{z13}.
1624 @itemx -mno-regnames
1625 Allow or disallow symbolic names for registers.
1626 @item -mwarn-areg-zero
1627 Warn whenever the operand for a base or index register has been specified
1628 but evaluates to zero.
1636 @xref{TIC6X Options}, for the options available when @value{AS} is configured
1637 for a TMS320C6000 processor.
1641 @c man begin OPTIONS
1642 The following options are available when @value{AS} is configured for a
1643 TMS320C6000 processor.
1645 @c man begin INCLUDE
1646 @include c-tic6x.texi
1647 @c ended inside the included file
1655 @xref{TILE-Gx Options}, for the options available when @value{AS} is configured
1656 for a TILE-Gx processor.
1660 @c man begin OPTIONS
1661 The following options are available when @value{AS} is configured for a TILE-Gx
1664 @c man begin INCLUDE
1665 @include c-tilegx.texi
1666 @c ended inside the included file
1674 @xref{Visium Options}, for the options available when @value{AS} is configured
1675 for a Visium processor.
1679 @c man begin OPTIONS
1680 The following option is available when @value{AS} is configured for a Visium
1683 @c man begin INCLUDE
1684 @include c-visium.texi
1685 @c ended inside the included file
1693 @xref{Xtensa Options}, for the options available when @value{AS} is configured
1694 for an Xtensa processor.
1698 @c man begin OPTIONS
1699 The following options are available when @value{AS} is configured for an
1702 @c man begin INCLUDE
1703 @include c-xtensa.texi
1704 @c ended inside the included file
1709 @c man begin OPTIONS
1712 The following options are available when @value{AS} is configured for
1713 a Z80 family processor.
1716 Assemble for Z80 processor.
1718 Assemble for R800 processor.
1719 @item -ignore-undocumented-instructions
1721 Assemble undocumented Z80 instructions that also work on R800 without warning.
1722 @item -ignore-unportable-instructions
1724 Assemble all undocumented Z80 instructions without warning.
1725 @item -warn-undocumented-instructions
1727 Issue a warning for undocumented Z80 instructions that also work on R800.
1728 @item -warn-unportable-instructions
1730 Issue a warning for undocumented Z80 instructions that do not work on R800.
1731 @item -forbid-undocumented-instructions
1733 Treat all undocumented instructions as errors.
1734 @item -forbid-unportable-instructions
1736 Treat undocumented Z80 instructions that do not work on R800 as errors.
1743 * Manual:: Structure of this Manual
1744 * GNU Assembler:: The GNU Assembler
1745 * Object Formats:: Object File Formats
1746 * Command Line:: Command Line
1747 * Input Files:: Input Files
1748 * Object:: Output (Object) File
1749 * Errors:: Error and Warning Messages
1753 @section Structure of this Manual
1755 @cindex manual, structure and purpose
1756 This manual is intended to describe what you need to know to use
1757 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1758 notation for symbols, constants, and expressions; the directives that
1759 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1762 We also cover special features in the @value{TARGET}
1763 configuration of @command{@value{AS}}, including assembler directives.
1766 This manual also describes some of the machine-dependent features of
1767 various flavors of the assembler.
1770 @cindex machine instructions (not covered)
1771 On the other hand, this manual is @emph{not} intended as an introduction
1772 to programming in assembly language---let alone programming in general!
1773 In a similar vein, we make no attempt to introduce the machine
1774 architecture; we do @emph{not} describe the instruction set, standard
1775 mnemonics, registers or addressing modes that are standard to a
1776 particular architecture.
1778 You may want to consult the manufacturer's
1779 machine architecture manual for this information.
1783 For information on the H8/300 machine instruction set, see @cite{H8/300
1784 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1785 Programming Manual} (Renesas).
1788 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1789 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1790 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1791 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1794 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1798 @c I think this is premature---doc@cygnus.com, 17jan1991
1800 Throughout this manual, we assume that you are running @dfn{GNU},
1801 the portable operating system from the @dfn{Free Software
1802 Foundation, Inc.}. This restricts our attention to certain kinds of
1803 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1804 once this assumption is granted examples and definitions need less
1807 @command{@value{AS}} is part of a team of programs that turn a high-level
1808 human-readable series of instructions into a low-level
1809 computer-readable series of instructions. Different versions of
1810 @command{@value{AS}} are used for different kinds of computer.
1813 @c There used to be a section "Terminology" here, which defined
1814 @c "contents", "byte", "word", and "long". Defining "word" to any
1815 @c particular size is confusing when the .word directive may generate 16
1816 @c bits on one machine and 32 bits on another; in general, for the user
1817 @c version of this manual, none of these terms seem essential to define.
1818 @c They were used very little even in the former draft of the manual;
1819 @c this draft makes an effort to avoid them (except in names of
1823 @section The GNU Assembler
1825 @c man begin DESCRIPTION
1827 @sc{gnu} @command{as} is really a family of assemblers.
1829 This manual describes @command{@value{AS}}, a member of that family which is
1830 configured for the @value{TARGET} architectures.
1832 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1833 should find a fairly similar environment when you use it on another
1834 architecture. Each version has much in common with the others,
1835 including object file formats, most assembler directives (often called
1836 @dfn{pseudo-ops}) and assembler syntax.@refill
1838 @cindex purpose of @sc{gnu} assembler
1839 @command{@value{AS}} is primarily intended to assemble the output of the
1840 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1841 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1842 assemble correctly everything that other assemblers for the same
1843 machine would assemble.
1845 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1848 @c This remark should appear in generic version of manual; assumption
1849 @c here is that generic version sets M680x0.
1850 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1851 assembler for the same architecture; for example, we know of several
1852 incompatible versions of 680x0 assembly language syntax.
1857 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1858 program in one pass of the source file. This has a subtle impact on the
1859 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1861 @node Object Formats
1862 @section Object File Formats
1864 @cindex object file format
1865 The @sc{gnu} assembler can be configured to produce several alternative
1866 object file formats. For the most part, this does not affect how you
1867 write assembly language programs; but directives for debugging symbols
1868 are typically different in different file formats. @xref{Symbol
1869 Attributes,,Symbol Attributes}.
1872 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1873 @value{OBJ-NAME} format object files.
1875 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1877 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1878 @code{b.out} or COFF format object files.
1881 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1882 SOM or ELF format object files.
1887 @section Command Line
1889 @cindex command line conventions
1891 After the program name @command{@value{AS}}, the command line may contain
1892 options and file names. Options may appear in any order, and may be
1893 before, after, or between file names. The order of file names is
1896 @cindex standard input, as input file
1898 @file{--} (two hyphens) by itself names the standard input file
1899 explicitly, as one of the files for @command{@value{AS}} to assemble.
1901 @cindex options, command line
1902 Except for @samp{--} any command line argument that begins with a
1903 hyphen (@samp{-}) is an option. Each option changes the behavior of
1904 @command{@value{AS}}. No option changes the way another option works. An
1905 option is a @samp{-} followed by one or more letters; the case of
1906 the letter is important. All options are optional.
1908 Some options expect exactly one file name to follow them. The file
1909 name may either immediately follow the option's letter (compatible
1910 with older assemblers) or it may be the next command argument (@sc{gnu}
1911 standard). These two command lines are equivalent:
1914 @value{AS} -o my-object-file.o mumble.s
1915 @value{AS} -omy-object-file.o mumble.s
1919 @section Input Files
1922 @cindex source program
1923 @cindex files, input
1924 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1925 describe the program input to one run of @command{@value{AS}}. The program may
1926 be in one or more files; how the source is partitioned into files
1927 doesn't change the meaning of the source.
1929 @c I added "con" prefix to "catenation" just to prove I can overcome my
1930 @c APL training... doc@cygnus.com
1931 The source program is a concatenation of the text in all the files, in the
1934 @c man begin DESCRIPTION
1935 Each time you run @command{@value{AS}} it assembles exactly one source
1936 program. The source program is made up of one or more files.
1937 (The standard input is also a file.)
1939 You give @command{@value{AS}} a command line that has zero or more input file
1940 names. The input files are read (from left file name to right). A
1941 command line argument (in any position) that has no special meaning
1942 is taken to be an input file name.
1944 If you give @command{@value{AS}} no file names it attempts to read one input file
1945 from the @command{@value{AS}} standard input, which is normally your terminal. You
1946 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1949 Use @samp{--} if you need to explicitly name the standard input file
1950 in your command line.
1952 If the source is empty, @command{@value{AS}} produces a small, empty object
1957 @subheading Filenames and Line-numbers
1959 @cindex input file linenumbers
1960 @cindex line numbers, in input files
1961 There are two ways of locating a line in the input file (or files) and
1962 either may be used in reporting error messages. One way refers to a line
1963 number in a physical file; the other refers to a line number in a
1964 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1966 @dfn{Physical files} are those files named in the command line given
1967 to @command{@value{AS}}.
1969 @dfn{Logical files} are simply names declared explicitly by assembler
1970 directives; they bear no relation to physical files. Logical file names help
1971 error messages reflect the original source file, when @command{@value{AS}} source
1972 is itself synthesized from other files. @command{@value{AS}} understands the
1973 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1974 @ref{File,,@code{.file}}.
1977 @section Output (Object) File
1983 Every time you run @command{@value{AS}} it produces an output file, which is
1984 your assembly language program translated into numbers. This file
1985 is the object file. Its default name is
1993 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1995 You can give it another name by using the @option{-o} option. Conventionally,
1996 object file names end with @file{.o}. The default name is used for historical
1997 reasons: older assemblers were capable of assembling self-contained programs
1998 directly into a runnable program. (For some formats, this isn't currently
1999 possible, but it can be done for the @code{a.out} format.)
2003 The object file is meant for input to the linker @code{@value{LD}}. It contains
2004 assembled program code, information to help @code{@value{LD}} integrate
2005 the assembled program into a runnable file, and (optionally) symbolic
2006 information for the debugger.
2008 @c link above to some info file(s) like the description of a.out.
2009 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
2012 @section Error and Warning Messages
2014 @c man begin DESCRIPTION
2016 @cindex error messages
2017 @cindex warning messages
2018 @cindex messages from assembler
2019 @command{@value{AS}} may write warnings and error messages to the standard error
2020 file (usually your terminal). This should not happen when a compiler
2021 runs @command{@value{AS}} automatically. Warnings report an assumption made so
2022 that @command{@value{AS}} could keep assembling a flawed program; errors report a
2023 grave problem that stops the assembly.
2027 @cindex format of warning messages
2028 Warning messages have the format
2031 file_name:@b{NNN}:Warning Message Text
2035 @cindex line numbers, in warnings/errors
2036 (where @b{NNN} is a line number). If a logical file name has been given
2037 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
2038 the current input file is used. If a logical line number was given
2040 (@pxref{Line,,@code{.line}})
2042 then it is used to calculate the number printed,
2043 otherwise the actual line in the current source file is printed. The
2044 message text is intended to be self explanatory (in the grand Unix
2047 @cindex format of error messages
2048 Error messages have the format
2050 file_name:@b{NNN}:FATAL:Error Message Text
2052 The file name and line number are derived as for warning
2053 messages. The actual message text may be rather less explanatory
2054 because many of them aren't supposed to happen.
2057 @chapter Command-Line Options
2059 @cindex options, all versions of assembler
2060 This chapter describes command-line options available in @emph{all}
2061 versions of the @sc{gnu} assembler; see @ref{Machine Dependencies},
2062 for options specific
2064 to the @value{TARGET} target.
2067 to particular machine architectures.
2070 @c man begin DESCRIPTION
2072 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
2073 you can use the @samp{-Wa} option to pass arguments through to the assembler.
2074 The assembler arguments must be separated from each other (and the @samp{-Wa})
2075 by commas. For example:
2078 gcc -c -g -O -Wa,-alh,-L file.c
2082 This passes two options to the assembler: @samp{-alh} (emit a listing to
2083 standard output with high-level and assembly source) and @samp{-L} (retain
2084 local symbols in the symbol table).
2086 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
2087 command-line options are automatically passed to the assembler by the compiler.
2088 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
2089 precisely what options it passes to each compilation pass, including the
2095 * a:: -a[cdghlns] enable listings
2096 * alternate:: --alternate enable alternate macro syntax
2097 * D:: -D for compatibility
2098 * f:: -f to work faster
2099 * I:: -I for .include search path
2100 @ifclear DIFF-TBL-KLUGE
2101 * K:: -K for compatibility
2103 @ifset DIFF-TBL-KLUGE
2104 * K:: -K for difference tables
2107 * L:: -L to retain local symbols
2108 * listing:: --listing-XXX to configure listing output
2109 * M:: -M or --mri to assemble in MRI compatibility mode
2110 * MD:: --MD for dependency tracking
2111 * o:: -o to name the object file
2112 * R:: -R to join data and text sections
2113 * statistics:: --statistics to see statistics about assembly
2114 * traditional-format:: --traditional-format for compatible output
2115 * v:: -v to announce version
2116 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
2117 * Z:: -Z to make object file even after errors
2121 @section Enable Listings: @option{-a[cdghlns]}
2131 @cindex listings, enabling
2132 @cindex assembly listings, enabling
2134 These options enable listing output from the assembler. By itself,
2135 @samp{-a} requests high-level, assembly, and symbols listing.
2136 You can use other letters to select specific options for the list:
2137 @samp{-ah} requests a high-level language listing,
2138 @samp{-al} requests an output-program assembly listing, and
2139 @samp{-as} requests a symbol table listing.
2140 High-level listings require that a compiler debugging option like
2141 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
2144 Use the @samp{-ag} option to print a first section with general assembly
2145 information, like @value{AS} version, switches passed, or time stamp.
2147 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
2148 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
2149 other conditional), or a true @code{.if} followed by an @code{.else}, will be
2150 omitted from the listing.
2152 Use the @samp{-ad} option to omit debugging directives from the
2155 Once you have specified one of these options, you can further control
2156 listing output and its appearance using the directives @code{.list},
2157 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
2159 The @samp{-an} option turns off all forms processing.
2160 If you do not request listing output with one of the @samp{-a} options, the
2161 listing-control directives have no effect.
2163 The letters after @samp{-a} may be combined into one option,
2164 @emph{e.g.}, @samp{-aln}.
2166 Note if the assembler source is coming from the standard input (e.g.,
2168 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
2169 is being used) then the listing will not contain any comments or preprocessor
2170 directives. This is because the listing code buffers input source lines from
2171 stdin only after they have been preprocessed by the assembler. This reduces
2172 memory usage and makes the code more efficient.
2175 @section @option{--alternate}
2178 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
2181 @section @option{-D}
2184 This option has no effect whatsoever, but it is accepted to make it more
2185 likely that scripts written for other assemblers also work with
2186 @command{@value{AS}}.
2189 @section Work Faster: @option{-f}
2192 @cindex trusted compiler
2193 @cindex faster processing (@option{-f})
2194 @samp{-f} should only be used when assembling programs written by a
2195 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
2196 and comment preprocessing on
2197 the input file(s) before assembling them. @xref{Preprocessing,
2201 @emph{Warning:} if you use @samp{-f} when the files actually need to be
2202 preprocessed (if they contain comments, for example), @command{@value{AS}} does
2207 @section @code{.include} Search Path: @option{-I} @var{path}
2209 @kindex -I @var{path}
2210 @cindex paths for @code{.include}
2211 @cindex search path for @code{.include}
2212 @cindex @code{include} directive search path
2213 Use this option to add a @var{path} to the list of directories
2214 @command{@value{AS}} searches for files specified in @code{.include}
2215 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
2216 many times as necessary to include a variety of paths. The current
2217 working directory is always searched first; after that, @command{@value{AS}}
2218 searches any @samp{-I} directories in the same order as they were
2219 specified (left to right) on the command line.
2222 @section Difference Tables: @option{-K}
2225 @ifclear DIFF-TBL-KLUGE
2226 On the @value{TARGET} family, this option is allowed, but has no effect. It is
2227 permitted for compatibility with the @sc{gnu} assembler on other platforms,
2228 where it can be used to warn when the assembler alters the machine code
2229 generated for @samp{.word} directives in difference tables. The @value{TARGET}
2230 family does not have the addressing limitations that sometimes lead to this
2231 alteration on other platforms.
2234 @ifset DIFF-TBL-KLUGE
2235 @cindex difference tables, warning
2236 @cindex warning for altered difference tables
2237 @command{@value{AS}} sometimes alters the code emitted for directives of the
2238 form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}.
2239 You can use the @samp{-K} option if you want a warning issued when this
2244 @section Include Local Symbols: @option{-L}
2247 @cindex local symbols, retaining in output
2248 Symbols beginning with system-specific local label prefixes, typically
2249 @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are
2250 called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see
2251 such symbols when debugging, because they are intended for the use of
2252 programs (like compilers) that compose assembler programs, not for your
2253 notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard
2254 such symbols, so you do not normally debug with them.
2256 This option tells @command{@value{AS}} to retain those local symbols
2257 in the object file. Usually if you do this you also tell the linker
2258 @code{@value{LD}} to preserve those symbols.
2261 @section Configuring listing output: @option{--listing}
2263 The listing feature of the assembler can be enabled via the command line switch
2264 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
2265 hex dump of the corresponding locations in the output object file, and displays
2266 them as a listing file. The format of this listing can be controlled by
2267 directives inside the assembler source (i.e., @code{.list} (@pxref{List}),
2268 @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}),
2269 @code{.psize} (@pxref{Psize}), and
2270 @code{.eject} (@pxref{Eject}) and also by the following switches:
2273 @item --listing-lhs-width=@samp{number}
2274 @kindex --listing-lhs-width
2275 @cindex Width of first line disassembly output
2276 Sets the maximum width, in words, of the first line of the hex byte dump. This
2277 dump appears on the left hand side of the listing output.
2279 @item --listing-lhs-width2=@samp{number}
2280 @kindex --listing-lhs-width2
2281 @cindex Width of continuation lines of disassembly output
2282 Sets the maximum width, in words, of any further lines of the hex byte dump for
2283 a given input source line. If this value is not specified, it defaults to being
2284 the same as the value specified for @samp{--listing-lhs-width}. If neither
2285 switch is used the default is to one.
2287 @item --listing-rhs-width=@samp{number}
2288 @kindex --listing-rhs-width
2289 @cindex Width of source line output
2290 Sets the maximum width, in characters, of the source line that is displayed
2291 alongside the hex dump. The default value for this parameter is 100. The
2292 source line is displayed on the right hand side of the listing output.
2294 @item --listing-cont-lines=@samp{number}
2295 @kindex --listing-cont-lines
2296 @cindex Maximum number of continuation lines
2297 Sets the maximum number of continuation lines of hex dump that will be
2298 displayed for a given single line of source input. The default value is 4.
2302 @section Assemble in MRI Compatibility Mode: @option{-M}
2305 @cindex MRI compatibility mode
2306 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
2307 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
2308 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
2309 configured target) assembler from Microtec Research. The exact nature of the
2310 MRI syntax will not be documented here; see the MRI manuals for more
2311 information. Note in particular that the handling of macros and macro
2312 arguments is somewhat different. The purpose of this option is to permit
2313 assembling existing MRI assembler code using @command{@value{AS}}.
2315 The MRI compatibility is not complete. Certain operations of the MRI assembler
2316 depend upon its object file format, and can not be supported using other object
2317 file formats. Supporting these would require enhancing each object file format
2318 individually. These are:
2321 @item global symbols in common section
2323 The m68k MRI assembler supports common sections which are merged by the linker.
2324 Other object file formats do not support this. @command{@value{AS}} handles
2325 common sections by treating them as a single common symbol. It permits local
2326 symbols to be defined within a common section, but it can not support global
2327 symbols, since it has no way to describe them.
2329 @item complex relocations
2331 The MRI assemblers support relocations against a negated section address, and
2332 relocations which combine the start addresses of two or more sections. These
2333 are not support by other object file formats.
2335 @item @code{END} pseudo-op specifying start address
2337 The MRI @code{END} pseudo-op permits the specification of a start address.
2338 This is not supported by other object file formats. The start address may
2339 instead be specified using the @option{-e} option to the linker, or in a linker
2342 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
2344 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
2345 name to the output file. This is not supported by other object file formats.
2347 @item @code{ORG} pseudo-op
2349 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
2350 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
2351 which changes the location within the current section. Absolute sections are
2352 not supported by other object file formats. The address of a section may be
2353 assigned within a linker script.
2356 There are some other features of the MRI assembler which are not supported by
2357 @command{@value{AS}}, typically either because they are difficult or because they
2358 seem of little consequence. Some of these may be supported in future releases.
2362 @item EBCDIC strings
2364 EBCDIC strings are not supported.
2366 @item packed binary coded decimal
2368 Packed binary coded decimal is not supported. This means that the @code{DC.P}
2369 and @code{DCB.P} pseudo-ops are not supported.
2371 @item @code{FEQU} pseudo-op
2373 The m68k @code{FEQU} pseudo-op is not supported.
2375 @item @code{NOOBJ} pseudo-op
2377 The m68k @code{NOOBJ} pseudo-op is not supported.
2379 @item @code{OPT} branch control options
2381 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
2382 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
2383 relaxes all branches, whether forward or backward, to an appropriate size, so
2384 these options serve no purpose.
2386 @item @code{OPT} list control options
2388 The following m68k @code{OPT} list control options are ignored: @code{C},
2389 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
2390 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
2392 @item other @code{OPT} options
2394 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
2395 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
2397 @item @code{OPT} @code{D} option is default
2399 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
2400 @code{OPT NOD} may be used to turn it off.
2402 @item @code{XREF} pseudo-op.
2404 The m68k @code{XREF} pseudo-op is ignored.
2406 @item @code{.debug} pseudo-op
2408 The i960 @code{.debug} pseudo-op is not supported.
2410 @item @code{.extended} pseudo-op
2412 The i960 @code{.extended} pseudo-op is not supported.
2414 @item @code{.list} pseudo-op.
2416 The various options of the i960 @code{.list} pseudo-op are not supported.
2418 @item @code{.optimize} pseudo-op
2420 The i960 @code{.optimize} pseudo-op is not supported.
2422 @item @code{.output} pseudo-op
2424 The i960 @code{.output} pseudo-op is not supported.
2426 @item @code{.setreal} pseudo-op
2428 The i960 @code{.setreal} pseudo-op is not supported.
2433 @section Dependency Tracking: @option{--MD}
2436 @cindex dependency tracking
2439 @command{@value{AS}} can generate a dependency file for the file it creates. This
2440 file consists of a single rule suitable for @code{make} describing the
2441 dependencies of the main source file.
2443 The rule is written to the file named in its argument.
2445 This feature is used in the automatic updating of makefiles.
2448 @section Name the Object File: @option{-o}
2451 @cindex naming object file
2452 @cindex object file name
2453 There is always one object file output when you run @command{@value{AS}}. By
2454 default it has the name
2457 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
2471 You use this option (which takes exactly one filename) to give the
2472 object file a different name.
2474 Whatever the object file is called, @command{@value{AS}} overwrites any
2475 existing file of the same name.
2478 @section Join Data and Text Sections: @option{-R}
2481 @cindex data and text sections, joining
2482 @cindex text and data sections, joining
2483 @cindex joining text and data sections
2484 @cindex merging text and data sections
2485 @option{-R} tells @command{@value{AS}} to write the object file as if all
2486 data-section data lives in the text section. This is only done at
2487 the very last moment: your binary data are the same, but data
2488 section parts are relocated differently. The data section part of
2489 your object file is zero bytes long because all its bytes are
2490 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
2492 When you specify @option{-R} it would be possible to generate shorter
2493 address displacements (because we do not have to cross between text and
2494 data section). We refrain from doing this simply for compatibility with
2495 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
2498 When @command{@value{AS}} is configured for COFF or ELF output,
2499 this option is only useful if you use sections named @samp{.text} and
2504 @option{-R} is not supported for any of the HPPA targets. Using
2505 @option{-R} generates a warning from @command{@value{AS}}.
2509 @section Display Assembly Statistics: @option{--statistics}
2511 @kindex --statistics
2512 @cindex statistics, about assembly
2513 @cindex time, total for assembly
2514 @cindex space used, maximum for assembly
2515 Use @samp{--statistics} to display two statistics about the resources used by
2516 @command{@value{AS}}: the maximum amount of space allocated during the assembly
2517 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
2520 @node traditional-format
2521 @section Compatible Output: @option{--traditional-format}
2523 @kindex --traditional-format
2524 For some targets, the output of @command{@value{AS}} is different in some ways
2525 from the output of some existing assembler. This switch requests
2526 @command{@value{AS}} to use the traditional format instead.
2528 For example, it disables the exception frame optimizations which
2529 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
2532 @section Announce Version: @option{-v}
2536 @cindex assembler version
2537 @cindex version of assembler
2538 You can find out what version of as is running by including the
2539 option @samp{-v} (which you can also spell as @samp{-version}) on the
2543 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
2545 @command{@value{AS}} should never give a warning or error message when
2546 assembling compiler output. But programs written by people often
2547 cause @command{@value{AS}} to give a warning that a particular assumption was
2548 made. All such warnings are directed to the standard error file.
2552 @cindex suppressing warnings
2553 @cindex warnings, suppressing
2554 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
2555 This only affects the warning messages: it does not change any particular of
2556 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
2559 @kindex --fatal-warnings
2560 @cindex errors, caused by warnings
2561 @cindex warnings, causing error
2562 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
2563 files that generate warnings to be in error.
2566 @cindex warnings, switching on
2567 You can switch these options off again by specifying @option{--warn}, which
2568 causes warnings to be output as usual.
2571 @section Generate Object File in Spite of Errors: @option{-Z}
2572 @cindex object file, after errors
2573 @cindex errors, continuing after
2574 After an error message, @command{@value{AS}} normally produces no output. If for
2575 some reason you are interested in object file output even after
2576 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
2577 option. If there are any errors, @command{@value{AS}} continues anyways, and
2578 writes an object file after a final warning message of the form @samp{@var{n}
2579 errors, @var{m} warnings, generating bad object file.}
2584 @cindex machine-independent syntax
2585 @cindex syntax, machine-independent
2586 This chapter describes the machine-independent syntax allowed in a
2587 source file. @command{@value{AS}} syntax is similar to what many other
2588 assemblers use; it is inspired by the BSD 4.2
2593 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
2597 * Preprocessing:: Preprocessing
2598 * Whitespace:: Whitespace
2599 * Comments:: Comments
2600 * Symbol Intro:: Symbols
2601 * Statements:: Statements
2602 * Constants:: Constants
2606 @section Preprocessing
2608 @cindex preprocessing
2609 The @command{@value{AS}} internal preprocessor:
2611 @cindex whitespace, removed by preprocessor
2613 adjusts and removes extra whitespace. It leaves one space or tab before
2614 the keywords on a line, and turns any other whitespace on the line into
2617 @cindex comments, removed by preprocessor
2619 removes all comments, replacing them with a single space, or an
2620 appropriate number of newlines.
2622 @cindex constants, converted by preprocessor
2624 converts character constants into the appropriate numeric values.
2627 It does not do macro processing, include file handling, or
2628 anything else you may get from your C compiler's preprocessor. You can
2629 do include file processing with the @code{.include} directive
2630 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2631 to get other ``CPP'' style preprocessing by giving the input file a
2632 @samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of
2633 Output, gcc.info, Using GNU CC}.
2635 Excess whitespace, comments, and character constants
2636 cannot be used in the portions of the input text that are not
2639 @cindex turning preprocessing on and off
2640 @cindex preprocessing, turning on and off
2643 If the first line of an input file is @code{#NO_APP} or if you use the
2644 @samp{-f} option, whitespace and comments are not removed from the input file.
2645 Within an input file, you can ask for whitespace and comment removal in
2646 specific portions of the by putting a line that says @code{#APP} before the
2647 text that may contain whitespace or comments, and putting a line that says
2648 @code{#NO_APP} after this text. This feature is mainly intend to support
2649 @code{asm} statements in compilers whose output is otherwise free of comments
2656 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2657 Whitespace is used to separate symbols, and to make programs neater for
2658 people to read. Unless within character constants
2659 (@pxref{Characters,,Character Constants}), any whitespace means the same
2660 as exactly one space.
2666 There are two ways of rendering comments to @command{@value{AS}}. In both
2667 cases the comment is equivalent to one space.
2669 Anything from @samp{/*} through the next @samp{*/} is a comment.
2670 This means you may not nest these comments.
2674 The only way to include a newline ('\n') in a comment
2675 is to use this sort of comment.
2678 /* This sort of comment does not nest. */
2681 @cindex line comment character
2682 Anything from a @dfn{line comment} character up to the next newline is
2683 considered a comment and is ignored. The line comment character is target
2684 specific, and some targets multiple comment characters. Some targets also have
2685 line comment characters that only work if they are the first character on a
2686 line. Some targets use a sequence of two characters to introduce a line
2687 comment. Some targets can also change their line comment characters depending
2688 upon command line options that have been used. For more details see the
2689 @emph{Syntax} section in the documentation for individual targets.
2691 If the line comment character is the hash sign (@samp{#}) then it still has the
2692 special ability to enable and disable preprocessing (@pxref{Preprocessing}) and
2693 to specify logical line numbers:
2696 @cindex lines starting with @code{#}
2697 @cindex logical line numbers
2698 To be compatible with past assemblers, lines that begin with @samp{#} have a
2699 special interpretation. Following the @samp{#} should be an absolute
2700 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2701 line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a
2702 new logical file name. The rest of the line, if any, should be whitespace.
2704 If the first non-whitespace characters on the line are not numeric,
2705 the line is ignored. (Just like a comment.)
2708 # This is an ordinary comment.
2709 # 42-6 "new_file_name" # New logical file name
2710 # This is logical line # 36.
2712 This feature is deprecated, and may disappear from future versions
2713 of @command{@value{AS}}.
2718 @cindex characters used in symbols
2719 @ifclear SPECIAL-SYMS
2720 A @dfn{symbol} is one or more characters chosen from the set of all
2721 letters (both upper and lower case), digits and the three characters
2727 A @dfn{symbol} is one or more characters chosen from the set of all
2728 letters (both upper and lower case), digits and the three characters
2729 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2735 On most machines, you can also use @code{$} in symbol names; exceptions
2736 are noted in @ref{Machine Dependencies}.
2738 No symbol may begin with a digit. Case is significant.
2739 There is no length limit: all characters are significant. Multibyte characters
2740 are supported. Symbols are delimited by characters not in that set, or by the
2741 beginning of a file (since the source program must end with a newline, the end
2742 of a file is not a possible symbol delimiter). @xref{Symbols}.
2743 @cindex length of symbols
2748 @cindex statements, structure of
2749 @cindex line separator character
2750 @cindex statement separator character
2752 A @dfn{statement} ends at a newline character (@samp{\n}) or a
2753 @dfn{line separator character}. The line separator character is target
2754 specific and described in the @emph{Syntax} section of each
2755 target's documentation. Not all targets support a line separator character.
2756 The newline or line separator character is considered to be part of the
2757 preceding statement. Newlines and separators within character constants are an
2758 exception: they do not end statements.
2760 @cindex newline, required at file end
2761 @cindex EOF, newline must precede
2762 It is an error to end any statement with end-of-file: the last
2763 character of any input file should be a newline.@refill
2765 An empty statement is allowed, and may include whitespace. It is ignored.
2767 @cindex instructions and directives
2768 @cindex directives and instructions
2769 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2770 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2772 A statement begins with zero or more labels, optionally followed by a
2773 key symbol which determines what kind of statement it is. The key
2774 symbol determines the syntax of the rest of the statement. If the
2775 symbol begins with a dot @samp{.} then the statement is an assembler
2776 directive: typically valid for any computer. If the symbol begins with
2777 a letter the statement is an assembly language @dfn{instruction}: it
2778 assembles into a machine language instruction.
2780 Different versions of @command{@value{AS}} for different computers
2781 recognize different instructions. In fact, the same symbol may
2782 represent a different instruction in a different computer's assembly
2786 @cindex @code{:} (label)
2787 @cindex label (@code{:})
2788 A label is a symbol immediately followed by a colon (@code{:}).
2789 Whitespace before a label or after a colon is permitted, but you may not
2790 have whitespace between a label's symbol and its colon. @xref{Labels}.
2793 For HPPA targets, labels need not be immediately followed by a colon, but
2794 the definition of a label must begin in column zero. This also implies that
2795 only one label may be defined on each line.
2799 label: .directive followed by something
2800 another_label: # This is an empty statement.
2801 instruction operand_1, operand_2, @dots{}
2808 A constant is a number, written so that its value is known by
2809 inspection, without knowing any context. Like this:
2812 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2813 .ascii "Ring the bell\7" # A string constant.
2814 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2815 .float 0f-314159265358979323846264338327\
2816 95028841971.693993751E-40 # - pi, a flonum.
2821 * Characters:: Character Constants
2822 * Numbers:: Number Constants
2826 @subsection Character Constants
2828 @cindex character constants
2829 @cindex constants, character
2830 There are two kinds of character constants. A @dfn{character} stands
2831 for one character in one byte and its value may be used in
2832 numeric expressions. String constants (properly called string
2833 @emph{literals}) are potentially many bytes and their values may not be
2834 used in arithmetic expressions.
2838 * Chars:: Characters
2842 @subsubsection Strings
2844 @cindex string constants
2845 @cindex constants, string
2846 A @dfn{string} is written between double-quotes. It may contain
2847 double-quotes or null characters. The way to get special characters
2848 into a string is to @dfn{escape} these characters: precede them with
2849 a backslash @samp{\} character. For example @samp{\\} represents
2850 one backslash: the first @code{\} is an escape which tells
2851 @command{@value{AS}} to interpret the second character literally as a backslash
2852 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2853 escape character). The complete list of escapes follows.
2855 @cindex escape codes, character
2856 @cindex character escape codes
2859 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2861 @cindex @code{\b} (backspace character)
2862 @cindex backspace (@code{\b})
2864 Mnemonic for backspace; for ASCII this is octal code 010.
2867 @c Mnemonic for EOText; for ASCII this is octal code 004.
2869 @cindex @code{\f} (formfeed character)
2870 @cindex formfeed (@code{\f})
2872 Mnemonic for FormFeed; for ASCII this is octal code 014.
2874 @cindex @code{\n} (newline character)
2875 @cindex newline (@code{\n})
2877 Mnemonic for newline; for ASCII this is octal code 012.
2880 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2882 @cindex @code{\r} (carriage return character)
2883 @cindex carriage return (@code{\r})
2885 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2888 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2889 @c other assemblers.
2891 @cindex @code{\t} (tab)
2892 @cindex tab (@code{\t})
2894 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2897 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2898 @c @item \x @var{digit} @var{digit} @var{digit}
2899 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2901 @cindex @code{\@var{ddd}} (octal character code)
2902 @cindex octal character code (@code{\@var{ddd}})
2903 @item \ @var{digit} @var{digit} @var{digit}
2904 An octal character code. The numeric code is 3 octal digits.
2905 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2906 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2908 @cindex @code{\@var{xd...}} (hex character code)
2909 @cindex hex character code (@code{\@var{xd...}})
2910 @item \@code{x} @var{hex-digits...}
2911 A hex character code. All trailing hex digits are combined. Either upper or
2912 lower case @code{x} works.
2914 @cindex @code{\\} (@samp{\} character)
2915 @cindex backslash (@code{\\})
2917 Represents one @samp{\} character.
2920 @c Represents one @samp{'} (accent acute) character.
2921 @c This is needed in single character literals
2922 @c (@xref{Characters,,Character Constants}.) to represent
2925 @cindex @code{\"} (doublequote character)
2926 @cindex doublequote (@code{\"})
2928 Represents one @samp{"} character. Needed in strings to represent
2929 this character, because an unescaped @samp{"} would end the string.
2931 @item \ @var{anything-else}
2932 Any other character when escaped by @kbd{\} gives a warning, but
2933 assembles as if the @samp{\} was not present. The idea is that if
2934 you used an escape sequence you clearly didn't want the literal
2935 interpretation of the following character. However @command{@value{AS}} has no
2936 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2937 code and warns you of the fact.
2940 Which characters are escapable, and what those escapes represent,
2941 varies widely among assemblers. The current set is what we think
2942 the BSD 4.2 assembler recognizes, and is a subset of what most C
2943 compilers recognize. If you are in doubt, do not use an escape
2947 @subsubsection Characters
2949 @cindex single character constant
2950 @cindex character, single
2951 @cindex constant, single character
2952 A single character may be written as a single quote immediately
2953 followed by that character. The same escapes apply to characters as
2954 to strings. So if you want to write the character backslash, you
2955 must write @kbd{'\\} where the first @code{\} escapes the second
2956 @code{\}. As you can see, the quote is an acute accent, not a
2957 grave accent. A newline
2959 @ifclear abnormal-separator
2960 (or semicolon @samp{;})
2962 @ifset abnormal-separator
2964 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2969 immediately following an acute accent is taken as a literal character
2970 and does not count as the end of a statement. The value of a character
2971 constant in a numeric expression is the machine's byte-wide code for
2972 that character. @command{@value{AS}} assumes your character code is ASCII:
2973 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2976 @subsection Number Constants
2978 @cindex constants, number
2979 @cindex number constants
2980 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2981 are stored in the target machine. @emph{Integers} are numbers that
2982 would fit into an @code{int} in the C language. @emph{Bignums} are
2983 integers, but they are stored in more than 32 bits. @emph{Flonums}
2984 are floating point numbers, described below.
2987 * Integers:: Integers
2992 * Bit Fields:: Bit Fields
2998 @subsubsection Integers
3000 @cindex constants, integer
3002 @cindex binary integers
3003 @cindex integers, binary
3004 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
3005 the binary digits @samp{01}.
3007 @cindex octal integers
3008 @cindex integers, octal
3009 An octal integer is @samp{0} followed by zero or more of the octal
3010 digits (@samp{01234567}).
3012 @cindex decimal integers
3013 @cindex integers, decimal
3014 A decimal integer starts with a non-zero digit followed by zero or
3015 more digits (@samp{0123456789}).
3017 @cindex hexadecimal integers
3018 @cindex integers, hexadecimal
3019 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
3020 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
3022 Integers have the usual values. To denote a negative integer, use
3023 the prefix operator @samp{-} discussed under expressions
3024 (@pxref{Prefix Ops,,Prefix Operators}).
3027 @subsubsection Bignums
3030 @cindex constants, bignum
3031 A @dfn{bignum} has the same syntax and semantics as an integer
3032 except that the number (or its negative) takes more than 32 bits to
3033 represent in binary. The distinction is made because in some places
3034 integers are permitted while bignums are not.
3037 @subsubsection Flonums
3039 @cindex floating point numbers
3040 @cindex constants, floating point
3042 @cindex precision, floating point
3043 A @dfn{flonum} represents a floating point number. The translation is
3044 indirect: a decimal floating point number from the text is converted by
3045 @command{@value{AS}} to a generic binary floating point number of more than
3046 sufficient precision. This generic floating point number is converted
3047 to a particular computer's floating point format (or formats) by a
3048 portion of @command{@value{AS}} specialized to that computer.
3050 A flonum is written by writing (in order)
3055 (@samp{0} is optional on the HPPA.)
3059 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
3061 @kbd{e} is recommended. Case is not important.
3063 @c FIXME: verify if flonum syntax really this vague for most cases
3064 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
3065 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
3068 On the H8/300, Renesas / SuperH SH,
3069 and AMD 29K architectures, the letter must be
3070 one of the letters @samp{DFPRSX} (in upper or lower case).
3072 On the ARC, the letter must be one of the letters @samp{DFRS}
3073 (in upper or lower case).
3075 On the Intel 960 architecture, the letter must be
3076 one of the letters @samp{DFT} (in upper or lower case).
3078 On the HPPA architecture, the letter must be @samp{E} (upper case only).
3082 One of the letters @samp{DFRS} (in upper or lower case).
3085 One of the letters @samp{DFPRSX} (in upper or lower case).
3088 The letter @samp{E} (upper case only).
3091 One of the letters @samp{DFT} (in upper or lower case).
3096 An optional sign: either @samp{+} or @samp{-}.
3099 An optional @dfn{integer part}: zero or more decimal digits.
3102 An optional @dfn{fractional part}: @samp{.} followed by zero
3103 or more decimal digits.
3106 An optional exponent, consisting of:
3110 An @samp{E} or @samp{e}.
3111 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
3112 @c principle this can perfectly well be different on different targets.
3114 Optional sign: either @samp{+} or @samp{-}.
3116 One or more decimal digits.
3121 At least one of the integer part or the fractional part must be
3122 present. The floating point number has the usual base-10 value.
3124 @command{@value{AS}} does all processing using integers. Flonums are computed
3125 independently of any floating point hardware in the computer running
3126 @command{@value{AS}}.
3130 @c Bit fields are written as a general facility but are also controlled
3131 @c by a conditional-compilation flag---which is as of now (21mar91)
3132 @c turned on only by the i960 config of GAS.
3134 @subsubsection Bit Fields
3137 @cindex constants, bit field
3138 You can also define numeric constants as @dfn{bit fields}.
3139 Specify two numbers separated by a colon---
3141 @var{mask}:@var{value}
3144 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
3147 The resulting number is then packed
3149 @c this conditional paren in case bit fields turned on elsewhere than 960
3150 (in host-dependent byte order)
3152 into a field whose width depends on which assembler directive has the
3153 bit-field as its argument. Overflow (a result from the bitwise and
3154 requiring more binary digits to represent) is not an error; instead,
3155 more constants are generated, of the specified width, beginning with the
3156 least significant digits.@refill
3158 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
3159 @code{.short}, and @code{.word} accept bit-field arguments.
3164 @chapter Sections and Relocation
3169 * Secs Background:: Background
3170 * Ld Sections:: Linker Sections
3171 * As Sections:: Assembler Internal Sections
3172 * Sub-Sections:: Sub-Sections
3176 @node Secs Background
3179 Roughly, a section is a range of addresses, with no gaps; all data
3180 ``in'' those addresses is treated the same for some particular purpose.
3181 For example there may be a ``read only'' section.
3183 @cindex linker, and assembler
3184 @cindex assembler, and linker
3185 The linker @code{@value{LD}} reads many object files (partial programs) and
3186 combines their contents to form a runnable program. When @command{@value{AS}}
3187 emits an object file, the partial program is assumed to start at address 0.
3188 @code{@value{LD}} assigns the final addresses for the partial program, so that
3189 different partial programs do not overlap. This is actually an
3190 oversimplification, but it suffices to explain how @command{@value{AS}} uses
3193 @code{@value{LD}} moves blocks of bytes of your program to their run-time
3194 addresses. These blocks slide to their run-time addresses as rigid
3195 units; their length does not change and neither does the order of bytes
3196 within them. Such a rigid unit is called a @emph{section}. Assigning
3197 run-time addresses to sections is called @dfn{relocation}. It includes
3198 the task of adjusting mentions of object-file addresses so they refer to
3199 the proper run-time addresses.
3201 For the H8/300, and for the Renesas / SuperH SH,
3202 @command{@value{AS}} pads sections if needed to
3203 ensure they end on a word (sixteen bit) boundary.
3206 @cindex standard assembler sections
3207 An object file written by @command{@value{AS}} has at least three sections, any
3208 of which may be empty. These are named @dfn{text}, @dfn{data} and
3213 When it generates COFF or ELF output,
3215 @command{@value{AS}} can also generate whatever other named sections you specify
3216 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
3217 If you do not use any directives that place output in the @samp{.text}
3218 or @samp{.data} sections, these sections still exist, but are empty.
3223 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
3225 @command{@value{AS}} can also generate whatever other named sections you
3226 specify using the @samp{.space} and @samp{.subspace} directives. See
3227 @cite{HP9000 Series 800 Assembly Language Reference Manual}
3228 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
3229 assembler directives.
3232 Additionally, @command{@value{AS}} uses different names for the standard
3233 text, data, and bss sections when generating SOM output. Program text
3234 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
3235 BSS into @samp{$BSS$}.
3239 Within the object file, the text section starts at address @code{0}, the
3240 data section follows, and the bss section follows the data section.
3243 When generating either SOM or ELF output files on the HPPA, the text
3244 section starts at address @code{0}, the data section at address
3245 @code{0x4000000}, and the bss section follows the data section.
3248 To let @code{@value{LD}} know which data changes when the sections are
3249 relocated, and how to change that data, @command{@value{AS}} also writes to the
3250 object file details of the relocation needed. To perform relocation
3251 @code{@value{LD}} must know, each time an address in the object
3255 Where in the object file is the beginning of this reference to
3258 How long (in bytes) is this reference?
3260 Which section does the address refer to? What is the numeric value of
3262 (@var{address}) @minus{} (@var{start-address of section})?
3265 Is the reference to an address ``Program-Counter relative''?
3268 @cindex addresses, format of
3269 @cindex section-relative addressing
3270 In fact, every address @command{@value{AS}} ever uses is expressed as
3272 (@var{section}) + (@var{offset into section})
3275 Further, most expressions @command{@value{AS}} computes have this section-relative
3278 (For some object formats, such as SOM for the HPPA, some expressions are
3279 symbol-relative instead.)
3282 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
3283 @var{N} into section @var{secname}.''
3285 Apart from text, data and bss sections you need to know about the
3286 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
3287 addresses in the absolute section remain unchanged. For example, address
3288 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
3289 @code{@value{LD}}. Although the linker never arranges two partial programs'
3290 data sections with overlapping addresses after linking, @emph{by definition}
3291 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
3292 part of a program is always the same address when the program is running as
3293 address @code{@{absolute@ 239@}} in any other part of the program.
3295 The idea of sections is extended to the @dfn{undefined} section. Any
3296 address whose section is unknown at assembly time is by definition
3297 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
3298 Since numbers are always defined, the only way to generate an undefined
3299 address is to mention an undefined symbol. A reference to a named
3300 common block would be such a symbol: its value is unknown at assembly
3301 time so it has section @emph{undefined}.
3303 By analogy the word @emph{section} is used to describe groups of sections in
3304 the linked program. @code{@value{LD}} puts all partial programs' text
3305 sections in contiguous addresses in the linked program. It is
3306 customary to refer to the @emph{text section} of a program, meaning all
3307 the addresses of all partial programs' text sections. Likewise for
3308 data and bss sections.
3310 Some sections are manipulated by @code{@value{LD}}; others are invented for
3311 use of @command{@value{AS}} and have no meaning except during assembly.
3314 @section Linker Sections
3315 @code{@value{LD}} deals with just four kinds of sections, summarized below.
3320 @cindex named sections
3321 @cindex sections, named
3322 @item named sections
3325 @cindex text section
3326 @cindex data section
3330 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
3331 separate but equal sections. Anything you can say of one section is
3334 When the program is running, however, it is
3335 customary for the text section to be unalterable. The
3336 text section is often shared among processes: it contains
3337 instructions, constants and the like. The data section of a running
3338 program is usually alterable: for example, C variables would be stored
3339 in the data section.
3344 This section contains zeroed bytes when your program begins running. It
3345 is used to hold uninitialized variables or common storage. The length of
3346 each partial program's bss section is important, but because it starts
3347 out containing zeroed bytes there is no need to store explicit zero
3348 bytes in the object file. The bss section was invented to eliminate
3349 those explicit zeros from object files.
3351 @cindex absolute section
3352 @item absolute section
3353 Address 0 of this section is always ``relocated'' to runtime address 0.
3354 This is useful if you want to refer to an address that @code{@value{LD}} must
3355 not change when relocating. In this sense we speak of absolute
3356 addresses being ``unrelocatable'': they do not change during relocation.
3358 @cindex undefined section
3359 @item undefined section
3360 This ``section'' is a catch-all for address references to objects not in
3361 the preceding sections.
3362 @c FIXME: ref to some other doc on obj-file formats could go here.
3365 @cindex relocation example
3366 An idealized example of three relocatable sections follows.
3368 The example uses the traditional section names @samp{.text} and @samp{.data}.
3370 Memory addresses are on the horizontal axis.
3374 @c END TEXI2ROFF-KILL
3377 partial program # 1: |ttttt|dddd|00|
3384 partial program # 2: |TTT|DDD|000|
3387 +--+---+-----+--+----+---+-----+~~
3388 linked program: | |TTT|ttttt| |dddd|DDD|00000|
3389 +--+---+-----+--+----+---+-----+~~
3391 addresses: 0 @dots{}
3398 \line{\it Partial program \#1: \hfil}
3399 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3400 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
3402 \line{\it Partial program \#2: \hfil}
3403 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3404 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
3406 \line{\it linked program: \hfil}
3407 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
3408 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
3409 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
3410 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
3412 \line{\it addresses: \hfil}
3416 @c END TEXI2ROFF-KILL
3419 @section Assembler Internal Sections
3421 @cindex internal assembler sections
3422 @cindex sections in messages, internal
3423 These sections are meant only for the internal use of @command{@value{AS}}. They
3424 have no meaning at run-time. You do not really need to know about these
3425 sections for most purposes; but they can be mentioned in @command{@value{AS}}
3426 warning messages, so it might be helpful to have an idea of their
3427 meanings to @command{@value{AS}}. These sections are used to permit the
3428 value of every expression in your assembly language program to be a
3429 section-relative address.
3432 @cindex assembler internal logic error
3433 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
3434 An internal assembler logic error has been found. This means there is a
3435 bug in the assembler.
3437 @cindex expr (internal section)
3439 The assembler stores complex expression internally as combinations of
3440 symbols. When it needs to represent an expression as a symbol, it puts
3441 it in the expr section.
3443 @c FIXME item transfer[t] vector preload
3444 @c FIXME item transfer[t] vector postload
3445 @c FIXME item register
3449 @section Sub-Sections
3451 @cindex numbered subsections
3452 @cindex grouping data
3458 fall into two sections: text and data.
3460 You may have separate groups of
3462 data in named sections
3466 data in named sections
3472 that you want to end up near to each other in the object file, even though they
3473 are not contiguous in the assembler source. @command{@value{AS}} allows you to
3474 use @dfn{subsections} for this purpose. Within each section, there can be
3475 numbered subsections with values from 0 to 8192. Objects assembled into the
3476 same subsection go into the object file together with other objects in the same
3477 subsection. For example, a compiler might want to store constants in the text
3478 section, but might not want to have them interspersed with the program being
3479 assembled. In this case, the compiler could issue a @samp{.text 0} before each
3480 section of code being output, and a @samp{.text 1} before each group of
3481 constants being output.
3483 Subsections are optional. If you do not use subsections, everything
3484 goes in subsection number zero.
3487 Each subsection is zero-padded up to a multiple of four bytes.
3488 (Subsections may be padded a different amount on different flavors
3489 of @command{@value{AS}}.)
3493 On the H8/300 platform, each subsection is zero-padded to a word
3494 boundary (two bytes).
3495 The same is true on the Renesas SH.
3498 @c FIXME section padding (alignment)?
3499 @c Rich Pixley says padding here depends on target obj code format; that
3500 @c doesn't seem particularly useful to say without further elaboration,
3501 @c so for now I say nothing about it. If this is a generic BFD issue,
3502 @c these paragraphs might need to vanish from this manual, and be
3503 @c discussed in BFD chapter of binutils (or some such).
3507 Subsections appear in your object file in numeric order, lowest numbered
3508 to highest. (All this to be compatible with other people's assemblers.)
3509 The object file contains no representation of subsections; @code{@value{LD}} and
3510 other programs that manipulate object files see no trace of them.
3511 They just see all your text subsections as a text section, and all your
3512 data subsections as a data section.
3514 To specify which subsection you want subsequent statements assembled
3515 into, use a numeric argument to specify it, in a @samp{.text
3516 @var{expression}} or a @samp{.data @var{expression}} statement.
3519 When generating COFF output, you
3524 can also use an extra subsection
3525 argument with arbitrary named sections: @samp{.section @var{name},
3530 When generating ELF output, you
3535 can also use the @code{.subsection} directive (@pxref{SubSection})
3536 to specify a subsection: @samp{.subsection @var{expression}}.
3538 @var{Expression} should be an absolute expression
3539 (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0}
3540 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3541 begins in @code{text 0}. For instance:
3543 .text 0 # The default subsection is text 0 anyway.
3544 .ascii "This lives in the first text subsection. *"
3546 .ascii "But this lives in the second text subsection."
3548 .ascii "This lives in the data section,"
3549 .ascii "in the first data subsection."
3551 .ascii "This lives in the first text section,"
3552 .ascii "immediately following the asterisk (*)."
3555 Each section has a @dfn{location counter} incremented by one for every byte
3556 assembled into that section. Because subsections are merely a convenience
3557 restricted to @command{@value{AS}} there is no concept of a subsection location
3558 counter. There is no way to directly manipulate a location counter---but the
3559 @code{.align} directive changes it, and any label definition captures its
3560 current value. The location counter of the section where statements are being
3561 assembled is said to be the @dfn{active} location counter.
3564 @section bss Section
3567 @cindex common variable storage
3568 The bss section is used for local common variable storage.
3569 You may allocate address space in the bss section, but you may
3570 not dictate data to load into it before your program executes. When
3571 your program starts running, all the contents of the bss
3572 section are zeroed bytes.
3574 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3575 @ref{Lcomm,,@code{.lcomm}}.
3577 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3578 another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}.
3581 When assembling for a target which supports multiple sections, such as ELF or
3582 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3583 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3584 section. Typically the section will only contain symbol definitions and
3585 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3592 Symbols are a central concept: the programmer uses symbols to name
3593 things, the linker uses symbols to link, and the debugger uses symbols
3597 @cindex debuggers, and symbol order
3598 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3599 the same order they were declared. This may break some debuggers.
3604 * Setting Symbols:: Giving Symbols Other Values
3605 * Symbol Names:: Symbol Names
3606 * Dot:: The Special Dot Symbol
3607 * Symbol Attributes:: Symbol Attributes
3614 A @dfn{label} is written as a symbol immediately followed by a colon
3615 @samp{:}. The symbol then represents the current value of the
3616 active location counter, and is, for example, a suitable instruction
3617 operand. You are warned if you use the same symbol to represent two
3618 different locations: the first definition overrides any other
3622 On the HPPA, the usual form for a label need not be immediately followed by a
3623 colon, but instead must start in column zero. Only one label may be defined on
3624 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3625 provides a special directive @code{.label} for defining labels more flexibly.
3628 @node Setting Symbols
3629 @section Giving Symbols Other Values
3631 @cindex assigning values to symbols
3632 @cindex symbol values, assigning
3633 A symbol can be given an arbitrary value by writing a symbol, followed
3634 by an equals sign @samp{=}, followed by an expression
3635 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3636 directive. @xref{Set,,@code{.set}}. In the same way, using a double
3637 equals sign @samp{=}@samp{=} here represents an equivalent of the
3638 @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}.
3641 Blackfin does not support symbol assignment with @samp{=}.
3645 @section Symbol Names
3647 @cindex symbol names
3648 @cindex names, symbol
3649 @ifclear SPECIAL-SYMS
3650 Symbol names begin with a letter or with one of @samp{._}. On most
3651 machines, you can also use @code{$} in symbol names; exceptions are
3652 noted in @ref{Machine Dependencies}. That character may be followed by any
3653 string of digits, letters, dollar signs (unless otherwise noted for a
3654 particular target machine), and underscores.
3658 Symbol names begin with a letter or with one of @samp{._}. On the
3659 Renesas SH you can also use @code{$} in symbol names. That
3660 character may be followed by any string of digits, letters, dollar signs (save
3661 on the H8/300), and underscores.
3665 Case of letters is significant: @code{foo} is a different symbol name
3668 Symbol names do not start with a digit. An exception to this rule is made for
3669 Local Labels. See below.
3671 Multibyte characters are supported. To generate a symbol name containing
3672 multibyte characters enclose it within double quotes and use escape codes. cf
3673 @xref{Strings}. Generating a multibyte symbol name from a label is not
3674 currently supported.
3676 Each symbol has exactly one name. Each name in an assembly language program
3677 refers to exactly one symbol. You may use that symbol name any number of times
3680 @subheading Local Symbol Names
3682 @cindex local symbol names
3683 @cindex symbol names, local
3684 A local symbol is any symbol beginning with certain local label prefixes.
3685 By default, the local label prefix is @samp{.L} for ELF systems or
3686 @samp{L} for traditional a.out systems, but each target may have its own
3687 set of local label prefixes.
3689 On the HPPA local symbols begin with @samp{L$}.
3692 Local symbols are defined and used within the assembler, but they are
3693 normally not saved in object files. Thus, they are not visible when debugging.
3694 You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols})
3695 to retain the local symbols in the object files.
3697 @subheading Local Labels
3699 @cindex local labels
3700 @cindex temporary symbol names
3701 @cindex symbol names, temporary
3702 Local labels are different from local symbols. Local labels help compilers and
3703 programmers use names temporarily. They create symbols which are guaranteed to
3704 be unique over the entire scope of the input source code and which can be
3705 referred to by a simple notation. To define a local label, write a label of
3706 the form @samp{@b{N}:} (where @b{N} represents any positive integer). To refer
3707 to the most recent previous definition of that label write @samp{@b{N}b}, using
3708 the same number as when you defined the label. To refer to the next definition
3709 of a local label, write @samp{@b{N}f}---the @samp{b} stands for ``backwards''
3710 and the @samp{f} stands for ``forwards''.
3712 There is no restriction on how you can use these labels, and you can reuse them
3713 too. So that it is possible to repeatedly define the same local label (using
3714 the same number @samp{@b{N}}), although you can only refer to the most recently
3715 defined local label of that number (for a backwards reference) or the next
3716 definition of a specific local label for a forward reference. It is also worth
3717 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3718 implemented in a slightly more efficient manner than the others.
3729 Which is the equivalent of:
3732 label_1: branch label_3
3733 label_2: branch label_1
3734 label_3: branch label_4
3735 label_4: branch label_3
3738 Local label names are only a notational device. They are immediately
3739 transformed into more conventional symbol names before the assembler uses them.
3740 The symbol names are stored in the symbol table, appear in error messages, and
3741 are optionally emitted to the object file. The names are constructed using
3745 @item @emph{local label prefix}
3746 All local symbols begin with the system-specific local label prefix.
3747 Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols
3748 that start with the local label prefix. These labels are
3749 used for symbols you are never intended to see. If you use the
3750 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3751 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3752 you may use them in debugging.
3755 This is the number that was used in the local label definition. So if the
3756 label is written @samp{55:} then the number is @samp{55}.
3759 This unusual character is included so you do not accidentally invent a symbol
3760 of the same name. The character has ASCII value of @samp{\002} (control-B).
3762 @item @emph{ordinal number}
3763 This is a serial number to keep the labels distinct. The first definition of
3764 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3765 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3766 the number @samp{1} and its 15th definition gets @samp{15} as well.
3769 So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and
3770 the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}.
3772 @subheading Dollar Local Labels
3773 @cindex dollar local symbols
3775 On some targets @code{@value{AS}} also supports an even more local form of
3776 local labels called dollar labels. These labels go out of scope (i.e., they
3777 become undefined) as soon as a non-local label is defined. Thus they remain
3778 valid for only a small region of the input source code. Normal local labels,
3779 by contrast, remain in scope for the entire file, or until they are redefined
3780 by another occurrence of the same local label.
3782 Dollar labels are defined in exactly the same way as ordinary local labels,
3783 except that they have a dollar sign suffix to their numeric value, e.g.,
3786 They can also be distinguished from ordinary local labels by their transformed
3787 names which use ASCII character @samp{\001} (control-A) as the magic character
3788 to distinguish them from ordinary labels. For example, the fifth definition of
3789 @samp{6$} may be named @samp{.L6@kbd{C-A}5}.
3792 @section The Special Dot Symbol
3794 @cindex dot (symbol)
3795 @cindex @code{.} (symbol)
3796 @cindex current address
3797 @cindex location counter
3798 The special symbol @samp{.} refers to the current address that
3799 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3800 .long .} defines @code{melvin} to contain its own address.
3801 Assigning a value to @code{.} is treated the same as a @code{.org}
3803 @ifclear no-space-dir
3804 Thus, the expression @samp{.=.+4} is the same as saying
3808 @node Symbol Attributes
3809 @section Symbol Attributes
3811 @cindex symbol attributes
3812 @cindex attributes, symbol
3813 Every symbol has, as well as its name, the attributes ``Value'' and
3814 ``Type''. Depending on output format, symbols can also have auxiliary
3817 The detailed definitions are in @file{a.out.h}.
3820 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3821 all these attributes, and probably won't warn you. This makes the
3822 symbol an externally defined symbol, which is generally what you
3826 * Symbol Value:: Value
3827 * Symbol Type:: Type
3830 * a.out Symbols:: Symbol Attributes: @code{a.out}
3834 * a.out Symbols:: Symbol Attributes: @code{a.out}
3837 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3842 * COFF Symbols:: Symbol Attributes for COFF
3845 * SOM Symbols:: Symbol Attributes for SOM
3852 @cindex value of a symbol
3853 @cindex symbol value
3854 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3855 location in the text, data, bss or absolute sections the value is the
3856 number of addresses from the start of that section to the label.
3857 Naturally for text, data and bss sections the value of a symbol changes
3858 as @code{@value{LD}} changes section base addresses during linking. Absolute
3859 symbols' values do not change during linking: that is why they are
3862 The value of an undefined symbol is treated in a special way. If it is
3863 0 then the symbol is not defined in this assembler source file, and
3864 @code{@value{LD}} tries to determine its value from other files linked into the
3865 same program. You make this kind of symbol simply by mentioning a symbol
3866 name without defining it. A non-zero value represents a @code{.comm}
3867 common declaration. The value is how much common storage to reserve, in
3868 bytes (addresses). The symbol refers to the first address of the
3874 @cindex type of a symbol
3876 The type attribute of a symbol contains relocation (section)
3877 information, any flag settings indicating that a symbol is external, and
3878 (optionally), other information for linkers and debuggers. The exact
3879 format depends on the object-code output format in use.
3884 @c The following avoids a "widow" subsection title. @group would be
3885 @c better if it were available outside examples.
3888 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3890 @cindex @code{b.out} symbol attributes
3891 @cindex symbol attributes, @code{b.out}
3892 These symbol attributes appear only when @command{@value{AS}} is configured for
3893 one of the Berkeley-descended object output formats---@code{a.out} or
3899 @subsection Symbol Attributes: @code{a.out}
3901 @cindex @code{a.out} symbol attributes
3902 @cindex symbol attributes, @code{a.out}
3908 @subsection Symbol Attributes: @code{a.out}
3910 @cindex @code{a.out} symbol attributes
3911 @cindex symbol attributes, @code{a.out}
3915 * Symbol Desc:: Descriptor
3916 * Symbol Other:: Other
3920 @subsubsection Descriptor
3922 @cindex descriptor, of @code{a.out} symbol
3923 This is an arbitrary 16-bit value. You may establish a symbol's
3924 descriptor value by using a @code{.desc} statement
3925 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3926 @command{@value{AS}}.
3929 @subsubsection Other
3931 @cindex other attribute, of @code{a.out} symbol
3932 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3937 @subsection Symbol Attributes for COFF
3939 @cindex COFF symbol attributes
3940 @cindex symbol attributes, COFF
3942 The COFF format supports a multitude of auxiliary symbol attributes;
3943 like the primary symbol attributes, they are set between @code{.def} and
3944 @code{.endef} directives.
3946 @subsubsection Primary Attributes
3948 @cindex primary attributes, COFF symbols
3949 The symbol name is set with @code{.def}; the value and type,
3950 respectively, with @code{.val} and @code{.type}.
3952 @subsubsection Auxiliary Attributes
3954 @cindex auxiliary attributes, COFF symbols
3955 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3956 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3957 table information for COFF.
3962 @subsection Symbol Attributes for SOM
3964 @cindex SOM symbol attributes
3965 @cindex symbol attributes, SOM
3967 The SOM format for the HPPA supports a multitude of symbol attributes set with
3968 the @code{.EXPORT} and @code{.IMPORT} directives.
3970 The attributes are described in @cite{HP9000 Series 800 Assembly
3971 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3972 @code{EXPORT} assembler directive documentation.
3976 @chapter Expressions
3980 @cindex numeric values
3981 An @dfn{expression} specifies an address or numeric value.
3982 Whitespace may precede and/or follow an expression.
3984 The result of an expression must be an absolute number, or else an offset into
3985 a particular section. If an expression is not absolute, and there is not
3986 enough information when @command{@value{AS}} sees the expression to know its
3987 section, a second pass over the source program might be necessary to interpret
3988 the expression---but the second pass is currently not implemented.
3989 @command{@value{AS}} aborts with an error message in this situation.
3992 * Empty Exprs:: Empty Expressions
3993 * Integer Exprs:: Integer Expressions
3997 @section Empty Expressions
3999 @cindex empty expressions
4000 @cindex expressions, empty
4001 An empty expression has no value: it is just whitespace or null.
4002 Wherever an absolute expression is required, you may omit the
4003 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
4004 is compatible with other assemblers.
4007 @section Integer Expressions
4009 @cindex integer expressions
4010 @cindex expressions, integer
4011 An @dfn{integer expression} is one or more @emph{arguments} delimited
4012 by @emph{operators}.
4015 * Arguments:: Arguments
4016 * Operators:: Operators
4017 * Prefix Ops:: Prefix Operators
4018 * Infix Ops:: Infix Operators
4022 @subsection Arguments
4024 @cindex expression arguments
4025 @cindex arguments in expressions
4026 @cindex operands in expressions
4027 @cindex arithmetic operands
4028 @dfn{Arguments} are symbols, numbers or subexpressions. In other
4029 contexts arguments are sometimes called ``arithmetic operands''. In
4030 this manual, to avoid confusing them with the ``instruction operands'' of
4031 the machine language, we use the term ``argument'' to refer to parts of
4032 expressions only, reserving the word ``operand'' to refer only to machine
4033 instruction operands.
4035 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
4036 @var{section} is one of text, data, bss, absolute,
4037 or undefined. @var{NNN} is a signed, 2's complement 32 bit
4040 Numbers are usually integers.
4042 A number can be a flonum or bignum. In this case, you are warned
4043 that only the low order 32 bits are used, and @command{@value{AS}} pretends
4044 these 32 bits are an integer. You may write integer-manipulating
4045 instructions that act on exotic constants, compatible with other
4048 @cindex subexpressions
4049 Subexpressions are a left parenthesis @samp{(} followed by an integer
4050 expression, followed by a right parenthesis @samp{)}; or a prefix
4051 operator followed by an argument.
4054 @subsection Operators
4056 @cindex operators, in expressions
4057 @cindex arithmetic functions
4058 @cindex functions, in expressions
4059 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
4060 operators are followed by an argument. Infix operators appear
4061 between their arguments. Operators may be preceded and/or followed by
4065 @subsection Prefix Operator
4067 @cindex prefix operators
4068 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
4069 one argument, which must be absolute.
4071 @c the tex/end tex stuff surrounding this small table is meant to make
4072 @c it align, on the printed page, with the similar table in the next
4073 @c section (which is inside an enumerate).
4075 \global\advance\leftskip by \itemindent
4080 @dfn{Negation}. Two's complement negation.
4082 @dfn{Complementation}. Bitwise not.
4086 \global\advance\leftskip by -\itemindent
4090 @subsection Infix Operators
4092 @cindex infix operators
4093 @cindex operators, permitted arguments
4094 @dfn{Infix operators} take two arguments, one on either side. Operators
4095 have precedence, but operations with equal precedence are performed left
4096 to right. Apart from @code{+} or @option{-}, both arguments must be
4097 absolute, and the result is absolute.
4100 @cindex operator precedence
4101 @cindex precedence of operators
4108 @dfn{Multiplication}.
4111 @dfn{Division}. Truncation is the same as the C operator @samp{/}
4117 @dfn{Shift Left}. Same as the C operator @samp{<<}.
4120 @dfn{Shift Right}. Same as the C operator @samp{>>}.
4124 Intermediate precedence
4129 @dfn{Bitwise Inclusive Or}.
4135 @dfn{Bitwise Exclusive Or}.
4138 @dfn{Bitwise Or Not}.
4145 @cindex addition, permitted arguments
4146 @cindex plus, permitted arguments
4147 @cindex arguments for addition
4149 @dfn{Addition}. If either argument is absolute, the result has the section of
4150 the other argument. You may not add together arguments from different
4153 @cindex subtraction, permitted arguments
4154 @cindex minus, permitted arguments
4155 @cindex arguments for subtraction
4157 @dfn{Subtraction}. If the right argument is absolute, the
4158 result has the section of the left argument.
4159 If both arguments are in the same section, the result is absolute.
4160 You may not subtract arguments from different sections.
4161 @c FIXME is there still something useful to say about undefined - undefined ?
4163 @cindex comparison expressions
4164 @cindex expressions, comparison
4169 @dfn{Is Not Equal To}
4173 @dfn{Is Greater Than}
4175 @dfn{Is Greater Than Or Equal To}
4177 @dfn{Is Less Than Or Equal To}
4179 The comparison operators can be used as infix operators. A true results has a
4180 value of -1 whereas a false result has a value of 0. Note, these operators
4181 perform signed comparisons.
4184 @item Lowest Precedence
4193 These two logical operations can be used to combine the results of sub
4194 expressions. Note, unlike the comparison operators a true result returns a
4195 value of 1 but a false results does still return 0. Also note that the logical
4196 or operator has a slightly lower precedence than logical and.
4201 In short, it's only meaningful to add or subtract the @emph{offsets} in an
4202 address; you can only have a defined section in one of the two arguments.
4205 @chapter Assembler Directives
4207 @cindex directives, machine independent
4208 @cindex pseudo-ops, machine independent
4209 @cindex machine independent directives
4210 All assembler directives have names that begin with a period (@samp{.}).
4211 The names are case insensitive for most targets, and usually written
4214 This chapter discusses directives that are available regardless of the
4215 target machine configuration for the @sc{gnu} assembler.
4217 Some machine configurations provide additional directives.
4218 @xref{Machine Dependencies}.
4221 @ifset machine-directives
4222 @xref{Machine Dependencies}, for additional directives.
4227 * Abort:: @code{.abort}
4229 * ABORT (COFF):: @code{.ABORT}
4232 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
4233 * Altmacro:: @code{.altmacro}
4234 * Ascii:: @code{.ascii "@var{string}"}@dots{}
4235 * Asciz:: @code{.asciz "@var{string}"}@dots{}
4236 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
4237 * Bundle directives:: @code{.bundle_align_mode @var{abs-expr}}, etc
4238 * Byte:: @code{.byte @var{expressions}}
4239 * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
4240 * Comm:: @code{.comm @var{symbol} , @var{length} }
4241 * Data:: @code{.data @var{subsection}}
4243 * Def:: @code{.def @var{name}}
4246 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
4252 * Double:: @code{.double @var{flonums}}
4253 * Eject:: @code{.eject}
4254 * Else:: @code{.else}
4255 * Elseif:: @code{.elseif}
4258 * Endef:: @code{.endef}
4261 * Endfunc:: @code{.endfunc}
4262 * Endif:: @code{.endif}
4263 * Equ:: @code{.equ @var{symbol}, @var{expression}}
4264 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
4265 * Eqv:: @code{.eqv @var{symbol}, @var{expression}}
4267 * Error:: @code{.error @var{string}}
4268 * Exitm:: @code{.exitm}
4269 * Extern:: @code{.extern}
4270 * Fail:: @code{.fail}
4271 * File:: @code{.file}
4272 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
4273 * Float:: @code{.float @var{flonums}}
4274 * Func:: @code{.func}
4275 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4277 * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
4278 * Hidden:: @code{.hidden @var{names}}
4281 * hword:: @code{.hword @var{expressions}}
4282 * Ident:: @code{.ident}
4283 * If:: @code{.if @var{absolute expression}}
4284 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4285 * Include:: @code{.include "@var{file}"}
4286 * Int:: @code{.int @var{expressions}}
4288 * Internal:: @code{.internal @var{names}}
4291 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
4292 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
4293 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
4294 * Lflags:: @code{.lflags}
4295 @ifclear no-line-dir
4296 * Line:: @code{.line @var{line-number}}
4299 * Linkonce:: @code{.linkonce [@var{type}]}
4300 * List:: @code{.list}
4301 * Ln:: @code{.ln @var{line-number}}
4302 * Loc:: @code{.loc @var{fileno} @var{lineno}}
4303 * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}}
4305 * Local:: @code{.local @var{names}}
4308 * Long:: @code{.long @var{expressions}}
4310 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
4313 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
4314 * MRI:: @code{.mri @var{val}}
4315 * Noaltmacro:: @code{.noaltmacro}
4316 * Nolist:: @code{.nolist}
4317 * Octa:: @code{.octa @var{bignums}}
4318 * Offset:: @code{.offset @var{loc}}
4319 * Org:: @code{.org @var{new-lc}, @var{fill}}
4320 * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4322 * PopSection:: @code{.popsection}
4323 * Previous:: @code{.previous}
4326 * Print:: @code{.print @var{string}}
4328 * Protected:: @code{.protected @var{names}}
4331 * Psize:: @code{.psize @var{lines}, @var{columns}}
4332 * Purgem:: @code{.purgem @var{name}}
4334 * PushSection:: @code{.pushsection @var{name}}
4337 * Quad:: @code{.quad @var{bignums}}
4338 * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
4339 * Rept:: @code{.rept @var{count}}
4340 * Sbttl:: @code{.sbttl "@var{subheading}"}
4342 * Scl:: @code{.scl @var{class}}
4345 * Section:: @code{.section @var{name}[, @var{flags}]}
4348 * Set:: @code{.set @var{symbol}, @var{expression}}
4349 * Short:: @code{.short @var{expressions}}
4350 * Single:: @code{.single @var{flonums}}
4352 * Size:: @code{.size [@var{name} , @var{expression}]}
4354 @ifclear no-space-dir
4355 * Skip:: @code{.skip @var{size} , @var{fill}}
4358 * Sleb128:: @code{.sleb128 @var{expressions}}
4359 @ifclear no-space-dir
4360 * Space:: @code{.space @var{size} , @var{fill}}
4363 * Stab:: @code{.stabd, .stabn, .stabs}
4366 * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
4367 * Struct:: @code{.struct @var{expression}}
4369 * SubSection:: @code{.subsection}
4370 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
4374 * Tag:: @code{.tag @var{structname}}
4377 * Text:: @code{.text @var{subsection}}
4378 * Title:: @code{.title "@var{heading}"}
4380 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
4383 * Uleb128:: @code{.uleb128 @var{expressions}}
4385 * Val:: @code{.val @var{addr}}
4389 * Version:: @code{.version "@var{string}"}
4390 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
4391 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
4394 * Warning:: @code{.warning @var{string}}
4395 * Weak:: @code{.weak @var{names}}
4396 * Weakref:: @code{.weakref @var{alias}, @var{symbol}}
4397 * Word:: @code{.word @var{expressions}}
4398 @ifclear no-space-dir
4399 * Zero:: @code{.zero @var{size}}
4401 * Deprecated:: Deprecated Directives
4405 @section @code{.abort}
4407 @cindex @code{abort} directive
4408 @cindex stopping the assembly
4409 This directive stops the assembly immediately. It is for
4410 compatibility with other assemblers. The original idea was that the
4411 assembly language source would be piped into the assembler. If the sender
4412 of the source quit, it could use this directive tells @command{@value{AS}} to
4413 quit also. One day @code{.abort} will not be supported.
4417 @section @code{.ABORT} (COFF)
4419 @cindex @code{ABORT} directive
4420 When producing COFF output, @command{@value{AS}} accepts this directive as a
4421 synonym for @samp{.abort}.
4424 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
4430 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4432 @cindex padding the location counter
4433 @cindex @code{align} directive
4434 Pad the location counter (in the current subsection) to a particular storage
4435 boundary. The first expression (which must be absolute) is the alignment
4436 required, as described below.
4438 The second expression (also absolute) gives the fill value to be stored in the
4439 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4440 padding bytes are normally zero. However, on some systems, if the section is
4441 marked as containing code and the fill value is omitted, the space is filled
4442 with no-op instructions.
4444 The third expression is also absolute, and is also optional. If it is present,
4445 it is the maximum number of bytes that should be skipped by this alignment
4446 directive. If doing the alignment would require skipping more bytes than the
4447 specified maximum, then the alignment is not done at all. You can omit the
4448 fill value (the second argument) entirely by simply using two commas after the
4449 required alignment; this can be useful if you want the alignment to be filled
4450 with no-op instructions when appropriate.
4452 The way the required alignment is specified varies from system to system.
4453 For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or1k,
4454 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
4455 alignment request in bytes. For example @samp{.align 8} advances
4456 the location counter until it is a multiple of 8. If the location counter
4457 is already a multiple of 8, no change is needed. For the tic54x, the
4458 first expression is the alignment request in words.
4460 For other systems, including ppc, i386 using a.out format, arm and
4461 strongarm, it is the
4462 number of low-order zero bits the location counter must have after
4463 advancement. For example @samp{.align 3} advances the location
4464 counter until it a multiple of 8. If the location counter is already a
4465 multiple of 8, no change is needed.
4467 This inconsistency is due to the different behaviors of the various
4468 native assemblers for these systems which GAS must emulate.
4469 GAS also provides @code{.balign} and @code{.p2align} directives,
4470 described later, which have a consistent behavior across all
4471 architectures (but are specific to GAS).
4474 @section @code{.altmacro}
4475 Enable alternate macro mode, enabling:
4478 @item LOCAL @var{name} [ , @dots{} ]
4479 One additional directive, @code{LOCAL}, is available. It is used to
4480 generate a string replacement for each of the @var{name} arguments, and
4481 replace any instances of @var{name} in each macro expansion. The
4482 replacement string is unique in the assembly, and different for each
4483 separate macro expansion. @code{LOCAL} allows you to write macros that
4484 define symbols, without fear of conflict between separate macro expansions.
4486 @item String delimiters
4487 You can write strings delimited in these other ways besides
4488 @code{"@var{string}"}:
4491 @item '@var{string}'
4492 You can delimit strings with single-quote characters.
4494 @item <@var{string}>
4495 You can delimit strings with matching angle brackets.
4498 @item single-character string escape
4499 To include any single character literally in a string (even if the
4500 character would otherwise have some special meaning), you can prefix the
4501 character with @samp{!} (an exclamation mark). For example, you can
4502 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4504 @item Expression results as strings
4505 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4506 and use the result as a string.
4510 @section @code{.ascii "@var{string}"}@dots{}
4512 @cindex @code{ascii} directive
4513 @cindex string literals
4514 @code{.ascii} expects zero or more string literals (@pxref{Strings})
4515 separated by commas. It assembles each string (with no automatic
4516 trailing zero byte) into consecutive addresses.
4519 @section @code{.asciz "@var{string}"}@dots{}
4521 @cindex @code{asciz} directive
4522 @cindex zero-terminated strings
4523 @cindex null-terminated strings
4524 @code{.asciz} is just like @code{.ascii}, but each string is followed by
4525 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
4528 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4530 @cindex padding the location counter given number of bytes
4531 @cindex @code{balign} directive
4532 Pad the location counter (in the current subsection) to a particular
4533 storage boundary. The first expression (which must be absolute) is the
4534 alignment request in bytes. For example @samp{.balign 8} advances
4535 the location counter until it is a multiple of 8. If the location counter
4536 is already a multiple of 8, no change is needed.
4538 The second expression (also absolute) gives the fill value to be stored in the
4539 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4540 padding bytes are normally zero. However, on some systems, if the section is
4541 marked as containing code and the fill value is omitted, the space is filled
4542 with no-op instructions.
4544 The third expression is also absolute, and is also optional. If it is present,
4545 it is the maximum number of bytes that should be skipped by this alignment
4546 directive. If doing the alignment would require skipping more bytes than the
4547 specified maximum, then the alignment is not done at all. You can omit the
4548 fill value (the second argument) entirely by simply using two commas after the
4549 required alignment; this can be useful if you want the alignment to be filled
4550 with no-op instructions when appropriate.
4552 @cindex @code{balignw} directive
4553 @cindex @code{balignl} directive
4554 The @code{.balignw} and @code{.balignl} directives are variants of the
4555 @code{.balign} directive. The @code{.balignw} directive treats the fill
4556 pattern as a two byte word value. The @code{.balignl} directives treats the
4557 fill pattern as a four byte longword value. For example, @code{.balignw
4558 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4559 filled in with the value 0x368d (the exact placement of the bytes depends upon
4560 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4563 @node Bundle directives
4564 @section Bundle directives
4565 @subsection @code{.bundle_align_mode @var{abs-expr}}
4566 @cindex @code{bundle_align_mode} directive
4568 @cindex instruction bundle
4569 @cindex aligned instruction bundle
4570 @code{.bundle_align_mode} enables or disables @dfn{aligned instruction
4571 bundle} mode. In this mode, sequences of adjacent instructions are grouped
4572 into fixed-sized @dfn{bundles}. If the argument is zero, this mode is
4573 disabled (which is the default state). If the argument it not zero, it
4574 gives the size of an instruction bundle as a power of two (as for the
4575 @code{.p2align} directive, @pxref{P2align}).
4577 For some targets, it's an ABI requirement that no instruction may span a
4578 certain aligned boundary. A @dfn{bundle} is simply a sequence of
4579 instructions that starts on an aligned boundary. For example, if
4580 @var{abs-expr} is @code{5} then the bundle size is 32, so each aligned
4581 chunk of 32 bytes is a bundle. When aligned instruction bundle mode is in
4582 effect, no single instruction may span a boundary between bundles. If an
4583 instruction would start too close to the end of a bundle for the length of
4584 that particular instruction to fit within the bundle, then the space at the
4585 end of that bundle is filled with no-op instructions so the instruction
4586 starts in the next bundle. As a corollary, it's an error if any single
4587 instruction's encoding is longer than the bundle size.
4589 @subsection @code{.bundle_lock} and @code{.bundle_unlock}
4590 @cindex @code{bundle_lock} directive
4591 @cindex @code{bundle_unlock} directive
4592 The @code{.bundle_lock} and directive @code{.bundle_unlock} directives
4593 allow explicit control over instruction bundle padding. These directives
4594 are only valid when @code{.bundle_align_mode} has been used to enable
4595 aligned instruction bundle mode. It's an error if they appear when
4596 @code{.bundle_align_mode} has not been used at all, or when the last
4597 directive was @w{@code{.bundle_align_mode 0}}.
4599 @cindex bundle-locked
4600 For some targets, it's an ABI requirement that certain instructions may
4601 appear only as part of specified permissible sequences of multiple
4602 instructions, all within the same bundle. A pair of @code{.bundle_lock}
4603 and @code{.bundle_unlock} directives define a @dfn{bundle-locked}
4604 instruction sequence. For purposes of aligned instruction bundle mode, a
4605 sequence starting with @code{.bundle_lock} and ending with
4606 @code{.bundle_unlock} is treated as a single instruction. That is, the
4607 entire sequence must fit into a single bundle and may not span a bundle
4608 boundary. If necessary, no-op instructions will be inserted before the
4609 first instruction of the sequence so that the whole sequence starts on an
4610 aligned bundle boundary. It's an error if the sequence is longer than the
4613 For convenience when using @code{.bundle_lock} and @code{.bundle_unlock}
4614 inside assembler macros (@pxref{Macro}), bundle-locked sequences may be
4615 nested. That is, a second @code{.bundle_lock} directive before the next
4616 @code{.bundle_unlock} directive has no effect except that it must be
4617 matched by another closing @code{.bundle_unlock} so that there is the
4618 same number of @code{.bundle_lock} and @code{.bundle_unlock} directives.
4621 @section @code{.byte @var{expressions}}
4623 @cindex @code{byte} directive
4624 @cindex integers, one byte
4625 @code{.byte} expects zero or more expressions, separated by commas.
4626 Each expression is assembled into the next byte.
4628 @node CFI directives
4629 @section CFI directives
4630 @subsection @code{.cfi_sections @var{section_list}}
4631 @cindex @code{cfi_sections} directive
4632 @code{.cfi_sections} may be used to specify whether CFI directives
4633 should emit @code{.eh_frame} section and/or @code{.debug_frame} section.
4634 If @var{section_list} is @code{.eh_frame}, @code{.eh_frame} is emitted,
4635 if @var{section_list} is @code{.debug_frame}, @code{.debug_frame} is emitted.
4636 To emit both use @code{.eh_frame, .debug_frame}. The default if this
4637 directive is not used is @code{.cfi_sections .eh_frame}.
4639 On targets that support compact unwinding tables these can be generated
4640 by specifying @code{.eh_frame_entry} instead of @code{.eh_frame}.
4642 @subsection @code{.cfi_startproc [simple]}
4643 @cindex @code{cfi_startproc} directive
4644 @code{.cfi_startproc} is used at the beginning of each function that
4645 should have an entry in @code{.eh_frame}. It initializes some internal
4646 data structures. Don't forget to close the function by
4647 @code{.cfi_endproc}.
4649 Unless @code{.cfi_startproc} is used along with parameter @code{simple}
4650 it also emits some architecture dependent initial CFI instructions.
4652 @subsection @code{.cfi_endproc}
4653 @cindex @code{cfi_endproc} directive
4654 @code{.cfi_endproc} is used at the end of a function where it closes its
4655 unwind entry previously opened by
4656 @code{.cfi_startproc}, and emits it to @code{.eh_frame}.
4658 @subsection @code{.cfi_personality @var{encoding} [, @var{exp}]}
4659 @cindex @code{cfi_personality} directive
4660 @code{.cfi_personality} defines personality routine and its encoding.
4661 @var{encoding} must be a constant determining how the personality
4662 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4663 argument is not present, otherwise second argument should be
4664 a constant or a symbol name. When using indirect encodings,
4665 the symbol provided should be the location where personality
4666 can be loaded from, not the personality routine itself.
4667 The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff},
4668 no personality routine.
4670 @subsection @code{.cfi_personality_id @var{id}}
4671 @cindex @code{cfi_personality_id} directive
4672 @code{cfi_personality_id} defines a personality routine by its index as
4673 defined in a compact unwinding format.
4674 Only valid when generating compact EH frames (i.e.
4675 with @code{.cfi_sections eh_frame_entry}.
4677 @subsection @code{.cfi_fde_data [@var{opcode1} [, @dots{}]]}
4678 @cindex @code{cfi_fde_data} directive
4679 @code{cfi_fde_data} is used to describe the compact unwind opcodes to be
4680 used for the current function. These are emitted inline in the
4681 @code{.eh_frame_entry} section if small enough and there is no LSDA, or
4682 in the @code{.gnu.extab} section otherwise.
4683 Only valid when generating compact EH frames (i.e.
4684 with @code{.cfi_sections eh_frame_entry}.
4686 @subsection @code{.cfi_lsda @var{encoding} [, @var{exp}]}
4687 @code{.cfi_lsda} defines LSDA and its encoding.
4688 @var{encoding} must be a constant determining how the LSDA
4689 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), the second
4690 argument is not present, otherwise the second argument should be a constant
4691 or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff},
4692 meaning that no LSDA is present.
4694 @subsection @code{.cfi_inline_lsda} [@var{align}]
4695 @code{.cfi_inline_lsda} marks the start of a LSDA data section and
4696 switches to the corresponding @code{.gnu.extab} section.
4697 Must be preceded by a CFI block containing a @code{.cfi_lsda} directive.
4698 Only valid when generating compact EH frames (i.e.
4699 with @code{.cfi_sections eh_frame_entry}.
4701 The table header and unwinding opcodes will be generated at this point,
4702 so that they are immediately followed by the LSDA data. The symbol
4703 referenced by the @code{.cfi_lsda} directive should still be defined
4704 in case a fallback FDE based encoding is used. The LSDA data is terminated
4705 by a section directive.
4707 The optional @var{align} argument specifies the alignment required.
4708 The alignment is specified as a power of two, as with the
4709 @code{.p2align} directive.
4711 @subsection @code{.cfi_def_cfa @var{register}, @var{offset}}
4712 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4713 address from @var{register} and add @var{offset} to it}.
4715 @subsection @code{.cfi_def_cfa_register @var{register}}
4716 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4717 now on @var{register} will be used instead of the old one. Offset
4720 @subsection @code{.cfi_def_cfa_offset @var{offset}}
4721 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4722 remains the same, but @var{offset} is new. Note that it is the
4723 absolute offset that will be added to a defined register to compute
4726 @subsection @code{.cfi_adjust_cfa_offset @var{offset}}
4727 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4728 value that is added/substracted from the previous offset.
4730 @subsection @code{.cfi_offset @var{register}, @var{offset}}
4731 Previous value of @var{register} is saved at offset @var{offset} from
4734 @subsection @code{.cfi_rel_offset @var{register}, @var{offset}}
4735 Previous value of @var{register} is saved at offset @var{offset} from
4736 the current CFA register. This is transformed to @code{.cfi_offset}
4737 using the known displacement of the CFA register from the CFA.
4738 This is often easier to use, because the number will match the
4739 code it's annotating.
4741 @subsection @code{.cfi_register @var{register1}, @var{register2}}
4742 Previous value of @var{register1} is saved in register @var{register2}.
4744 @subsection @code{.cfi_restore @var{register}}
4745 @code{.cfi_restore} says that the rule for @var{register} is now the
4746 same as it was at the beginning of the function, after all initial
4747 instruction added by @code{.cfi_startproc} were executed.
4749 @subsection @code{.cfi_undefined @var{register}}
4750 From now on the previous value of @var{register} can't be restored anymore.
4752 @subsection @code{.cfi_same_value @var{register}}
4753 Current value of @var{register} is the same like in the previous frame,
4754 i.e. no restoration needed.
4756 @subsection @code{.cfi_remember_state},
4757 First save all current rules for all registers by @code{.cfi_remember_state},
4758 then totally screw them up by subsequent @code{.cfi_*} directives and when
4759 everything is hopelessly bad, use @code{.cfi_restore_state} to restore
4760 the previous saved state.
4762 @subsection @code{.cfi_return_column @var{register}}
4763 Change return column @var{register}, i.e. the return address is either
4764 directly in @var{register} or can be accessed by rules for @var{register}.
4766 @subsection @code{.cfi_signal_frame}
4767 Mark current function as signal trampoline.
4769 @subsection @code{.cfi_window_save}
4770 SPARC register window has been saved.
4772 @subsection @code{.cfi_escape} @var{expression}[, @dots{}]
4773 Allows the user to add arbitrary bytes to the unwind info. One
4774 might use this to add OS-specific CFI opcodes, or generic CFI
4775 opcodes that GAS does not yet support.
4777 @subsection @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}}
4778 The current value of @var{register} is @var{label}. The value of @var{label}
4779 will be encoded in the output file according to @var{encoding}; see the
4780 description of @code{.cfi_personality} for details on this encoding.
4782 The usefulness of equating a register to a fixed label is probably
4783 limited to the return address register. Here, it can be useful to
4784 mark a code segment that has only one return address which is reached
4785 by a direct branch and no copy of the return address exists in memory
4786 or another register.
4789 @section @code{.comm @var{symbol} , @var{length} }
4791 @cindex @code{comm} directive
4792 @cindex symbol, common
4793 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
4794 common symbol in one object file may be merged with a defined or common symbol
4795 of the same name in another object file. If @code{@value{LD}} does not see a
4796 definition for the symbol--just one or more common symbols--then it will
4797 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
4798 absolute expression. If @code{@value{LD}} sees multiple common symbols with
4799 the same name, and they do not all have the same size, it will allocate space
4800 using the largest size.
4803 When using ELF or (as a GNU extension) PE, the @code{.comm} directive takes
4804 an optional third argument. This is the desired alignment of the symbol,
4805 specified for ELF as a byte boundary (for example, an alignment of 16 means
4806 that the least significant 4 bits of the address should be zero), and for PE
4807 as a power of two (for example, an alignment of 5 means aligned to a 32-byte
4808 boundary). The alignment must be an absolute expression, and it must be a
4809 power of two. If @code{@value{LD}} allocates uninitialized memory for the
4810 common symbol, it will use the alignment when placing the symbol. If no
4811 alignment is specified, @command{@value{AS}} will set the alignment to the
4812 largest power of two less than or equal to the size of the symbol, up to a
4813 maximum of 16 on ELF, or the default section alignment of 4 on PE@footnote{This
4814 is not the same as the executable image file alignment controlled by @code{@value{LD}}'s
4815 @samp{--section-alignment} option; image file sections in PE are aligned to
4816 multiples of 4096, which is far too large an alignment for ordinary variables.
4817 It is rather the default alignment for (non-debug) sections within object
4818 (@samp{*.o}) files, which are less strictly aligned.}.
4822 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4823 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4827 @section @code{.data @var{subsection}}
4829 @cindex @code{data} directive
4830 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4831 end of the data subsection numbered @var{subsection} (which is an
4832 absolute expression). If @var{subsection} is omitted, it defaults
4837 @section @code{.def @var{name}}
4839 @cindex @code{def} directive
4840 @cindex COFF symbols, debugging
4841 @cindex debugging COFF symbols
4842 Begin defining debugging information for a symbol @var{name}; the
4843 definition extends until the @code{.endef} directive is encountered.
4846 This directive is only observed when @command{@value{AS}} is configured for COFF
4847 format output; when producing @code{b.out}, @samp{.def} is recognized,
4854 @section @code{.desc @var{symbol}, @var{abs-expression}}
4856 @cindex @code{desc} directive
4857 @cindex COFF symbol descriptor
4858 @cindex symbol descriptor, COFF
4859 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4860 to the low 16 bits of an absolute expression.
4863 The @samp{.desc} directive is not available when @command{@value{AS}} is
4864 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4865 object format. For the sake of compatibility, @command{@value{AS}} accepts
4866 it, but produces no output, when configured for COFF.
4872 @section @code{.dim}
4874 @cindex @code{dim} directive
4875 @cindex COFF auxiliary symbol information
4876 @cindex auxiliary symbol information, COFF
4877 This directive is generated by compilers to include auxiliary debugging
4878 information in the symbol table. It is only permitted inside
4879 @code{.def}/@code{.endef} pairs.
4882 @samp{.dim} is only meaningful when generating COFF format output; when
4883 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4889 @section @code{.double @var{flonums}}
4891 @cindex @code{double} directive
4892 @cindex floating point numbers (double)
4893 @code{.double} expects zero or more flonums, separated by commas. It
4894 assembles floating point numbers.
4896 The exact kind of floating point numbers emitted depends on how
4897 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4901 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4902 in @sc{ieee} format.
4907 @section @code{.eject}
4909 @cindex @code{eject} directive
4910 @cindex new page, in listings
4911 @cindex page, in listings
4912 @cindex listing control: new page
4913 Force a page break at this point, when generating assembly listings.
4916 @section @code{.else}
4918 @cindex @code{else} directive
4919 @code{.else} is part of the @command{@value{AS}} support for conditional
4920 assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section
4921 of code to be assembled if the condition for the preceding @code{.if}
4925 @section @code{.elseif}
4927 @cindex @code{elseif} directive
4928 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4929 assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new
4930 @code{.if} block that would otherwise fill the entire @code{.else} section.
4933 @section @code{.end}
4935 @cindex @code{end} directive
4936 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4937 process anything in the file past the @code{.end} directive.
4941 @section @code{.endef}
4943 @cindex @code{endef} directive
4944 This directive flags the end of a symbol definition begun with
4948 @samp{.endef} is only meaningful when generating COFF format output; if
4949 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4950 directive but ignores it.
4955 @section @code{.endfunc}
4956 @cindex @code{endfunc} directive
4957 @code{.endfunc} marks the end of a function specified with @code{.func}.
4960 @section @code{.endif}
4962 @cindex @code{endif} directive
4963 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4964 it marks the end of a block of code that is only assembled
4965 conditionally. @xref{If,,@code{.if}}.
4968 @section @code{.equ @var{symbol}, @var{expression}}
4970 @cindex @code{equ} directive
4971 @cindex assigning values to symbols
4972 @cindex symbols, assigning values to
4973 This directive sets the value of @var{symbol} to @var{expression}.
4974 It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}.
4977 The syntax for @code{equ} on the HPPA is
4978 @samp{@var{symbol} .equ @var{expression}}.
4982 The syntax for @code{equ} on the Z80 is
4983 @samp{@var{symbol} equ @var{expression}}.
4984 On the Z80 it is an eror if @var{symbol} is already defined,
4985 but the symbol is not protected from later redefinition.
4986 Compare @ref{Equiv}.
4990 @section @code{.equiv @var{symbol}, @var{expression}}
4991 @cindex @code{equiv} directive
4992 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4993 the assembler will signal an error if @var{symbol} is already defined. Note a
4994 symbol which has been referenced but not actually defined is considered to be
4997 Except for the contents of the error message, this is roughly equivalent to
5004 plus it protects the symbol from later redefinition.
5007 @section @code{.eqv @var{symbol}, @var{expression}}
5008 @cindex @code{eqv} directive
5009 The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to
5010 evaluate the expression or any part of it immediately. Instead each time
5011 the resulting symbol is used in an expression, a snapshot of its current
5015 @section @code{.err}
5016 @cindex @code{err} directive
5017 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
5018 message and, unless the @option{-Z} option was used, it will not generate an
5019 object file. This can be used to signal an error in conditionally compiled code.
5022 @section @code{.error "@var{string}"}
5023 @cindex error directive
5025 Similarly to @code{.err}, this directive emits an error, but you can specify a
5026 string that will be emitted as the error message. If you don't specify the
5027 message, it defaults to @code{".error directive invoked in source file"}.
5028 @xref{Errors, ,Error and Warning Messages}.
5031 .error "This code has not been assembled and tested."
5035 @section @code{.exitm}
5036 Exit early from the current macro definition. @xref{Macro}.
5039 @section @code{.extern}
5041 @cindex @code{extern} directive
5042 @code{.extern} is accepted in the source program---for compatibility
5043 with other assemblers---but it is ignored. @command{@value{AS}} treats
5044 all undefined symbols as external.
5047 @section @code{.fail @var{expression}}
5049 @cindex @code{fail} directive
5050 Generates an error or a warning. If the value of the @var{expression} is 500
5051 or more, @command{@value{AS}} will print a warning message. If the value is less
5052 than 500, @command{@value{AS}} will print an error message. The message will
5053 include the value of @var{expression}. This can occasionally be useful inside
5054 complex nested macros or conditional assembly.
5057 @section @code{.file}
5058 @cindex @code{file} directive
5060 @ifclear no-file-dir
5061 There are two different versions of the @code{.file} directive. Targets
5062 that support DWARF2 line number information use the DWARF2 version of
5063 @code{.file}. Other targets use the default version.
5065 @subheading Default Version
5067 @cindex logical file name
5068 @cindex file name, logical
5069 This version of the @code{.file} directive tells @command{@value{AS}} that we
5070 are about to start a new logical file. The syntax is:
5076 @var{string} is the new file name. In general, the filename is
5077 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
5078 to specify an empty file name, you must give the quotes--@code{""}. This
5079 statement may go away in future: it is only recognized to be compatible with
5080 old @command{@value{AS}} programs.
5082 @subheading DWARF2 Version
5085 When emitting DWARF2 line number information, @code{.file} assigns filenames
5086 to the @code{.debug_line} file name table. The syntax is:
5089 .file @var{fileno} @var{filename}
5092 The @var{fileno} operand should be a unique positive integer to use as the
5093 index of the entry in the table. The @var{filename} operand is a C string
5096 The detail of filename indices is exposed to the user because the filename
5097 table is shared with the @code{.debug_info} section of the DWARF2 debugging
5098 information, and thus the user must know the exact indices that table
5102 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
5104 @cindex @code{fill} directive
5105 @cindex writing patterns in memory
5106 @cindex patterns, writing in memory
5107 @var{repeat}, @var{size} and @var{value} are absolute expressions.
5108 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
5109 may be zero or more. @var{Size} may be zero or more, but if it is
5110 more than 8, then it is deemed to have the value 8, compatible with
5111 other people's assemblers. The contents of each @var{repeat} bytes
5112 is taken from an 8-byte number. The highest order 4 bytes are
5113 zero. The lowest order 4 bytes are @var{value} rendered in the
5114 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
5115 Each @var{size} bytes in a repetition is taken from the lowest order
5116 @var{size} bytes of this number. Again, this bizarre behavior is
5117 compatible with other people's assemblers.
5119 @var{size} and @var{value} are optional.
5120 If the second comma and @var{value} are absent, @var{value} is
5121 assumed zero. If the first comma and following tokens are absent,
5122 @var{size} is assumed to be 1.
5125 @section @code{.float @var{flonums}}
5127 @cindex floating point numbers (single)
5128 @cindex @code{float} directive
5129 This directive assembles zero or more flonums, separated by commas. It
5130 has the same effect as @code{.single}.
5132 The exact kind of floating point numbers emitted depends on how
5133 @command{@value{AS}} is configured.
5134 @xref{Machine Dependencies}.
5138 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
5139 in @sc{ieee} format.
5144 @section @code{.func @var{name}[,@var{label}]}
5145 @cindex @code{func} directive
5146 @code{.func} emits debugging information to denote function @var{name}, and
5147 is ignored unless the file is assembled with debugging enabled.
5148 Only @samp{--gstabs[+]} is currently supported.
5149 @var{label} is the entry point of the function and if omitted @var{name}
5150 prepended with the @samp{leading char} is used.
5151 @samp{leading char} is usually @code{_} or nothing, depending on the target.
5152 All functions are currently defined to have @code{void} return type.
5153 The function must be terminated with @code{.endfunc}.
5156 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
5158 @cindex @code{global} directive
5159 @cindex symbol, making visible to linker
5160 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
5161 @var{symbol} in your partial program, its value is made available to
5162 other partial programs that are linked with it. Otherwise,
5163 @var{symbol} takes its attributes from a symbol of the same name
5164 from another file linked into the same program.
5166 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
5167 compatibility with other assemblers.
5170 On the HPPA, @code{.global} is not always enough to make it accessible to other
5171 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
5172 @xref{HPPA Directives, ,HPPA Assembler Directives}.
5177 @section @code{.gnu_attribute @var{tag},@var{value}}
5178 Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
5181 @section @code{.hidden @var{names}}
5183 @cindex @code{hidden} directive
5185 This is one of the ELF visibility directives. The other two are
5186 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
5187 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5189 This directive overrides the named symbols default visibility (which is set by
5190 their binding: local, global or weak). The directive sets the visibility to
5191 @code{hidden} which means that the symbols are not visible to other components.
5192 Such symbols are always considered to be @code{protected} as well.
5196 @section @code{.hword @var{expressions}}
5198 @cindex @code{hword} directive
5199 @cindex integers, 16-bit
5200 @cindex numbers, 16-bit
5201 @cindex sixteen bit integers
5202 This expects zero or more @var{expressions}, and emits
5203 a 16 bit number for each.
5206 This directive is a synonym for @samp{.short}; depending on the target
5207 architecture, it may also be a synonym for @samp{.word}.
5211 This directive is a synonym for @samp{.short}.
5214 This directive is a synonym for both @samp{.short} and @samp{.word}.
5219 @section @code{.ident}
5221 @cindex @code{ident} directive
5223 This directive is used by some assemblers to place tags in object files. The
5224 behavior of this directive varies depending on the target. When using the
5225 a.out object file format, @command{@value{AS}} simply accepts the directive for
5226 source-file compatibility with existing assemblers, but does not emit anything
5227 for it. When using COFF, comments are emitted to the @code{.comment} or
5228 @code{.rdata} section, depending on the target. When using ELF, comments are
5229 emitted to the @code{.comment} section.
5232 @section @code{.if @var{absolute expression}}
5234 @cindex conditional assembly
5235 @cindex @code{if} directive
5236 @code{.if} marks the beginning of a section of code which is only
5237 considered part of the source program being assembled if the argument
5238 (which must be an @var{absolute expression}) is non-zero. The end of
5239 the conditional section of code must be marked by @code{.endif}
5240 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
5241 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
5242 If you have several conditions to check, @code{.elseif} may be used to avoid
5243 nesting blocks if/else within each subsequent @code{.else} block.
5245 The following variants of @code{.if} are also supported:
5247 @cindex @code{ifdef} directive
5248 @item .ifdef @var{symbol}
5249 Assembles the following section of code if the specified @var{symbol}
5250 has been defined. Note a symbol which has been referenced but not yet defined
5251 is considered to be undefined.
5253 @cindex @code{ifb} directive
5254 @item .ifb @var{text}
5255 Assembles the following section of code if the operand is blank (empty).
5257 @cindex @code{ifc} directive
5258 @item .ifc @var{string1},@var{string2}
5259 Assembles the following section of code if the two strings are the same. The
5260 strings may be optionally quoted with single quotes. If they are not quoted,
5261 the first string stops at the first comma, and the second string stops at the
5262 end of the line. Strings which contain whitespace should be quoted. The
5263 string comparison is case sensitive.
5265 @cindex @code{ifeq} directive
5266 @item .ifeq @var{absolute expression}
5267 Assembles the following section of code if the argument is zero.
5269 @cindex @code{ifeqs} directive
5270 @item .ifeqs @var{string1},@var{string2}
5271 Another form of @code{.ifc}. The strings must be quoted using double quotes.
5273 @cindex @code{ifge} directive
5274 @item .ifge @var{absolute expression}
5275 Assembles the following section of code if the argument is greater than or
5278 @cindex @code{ifgt} directive
5279 @item .ifgt @var{absolute expression}
5280 Assembles the following section of code if the argument is greater than zero.
5282 @cindex @code{ifle} directive
5283 @item .ifle @var{absolute expression}
5284 Assembles the following section of code if the argument is less than or equal
5287 @cindex @code{iflt} directive
5288 @item .iflt @var{absolute expression}
5289 Assembles the following section of code if the argument is less than zero.
5291 @cindex @code{ifnb} directive
5292 @item .ifnb @var{text}
5293 Like @code{.ifb}, but the sense of the test is reversed: this assembles the
5294 following section of code if the operand is non-blank (non-empty).
5296 @cindex @code{ifnc} directive
5297 @item .ifnc @var{string1},@var{string2}.
5298 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
5299 following section of code if the two strings are not the same.
5301 @cindex @code{ifndef} directive
5302 @cindex @code{ifnotdef} directive
5303 @item .ifndef @var{symbol}
5304 @itemx .ifnotdef @var{symbol}
5305 Assembles the following section of code if the specified @var{symbol}
5306 has not been defined. Both spelling variants are equivalent. Note a symbol
5307 which has been referenced but not yet defined is considered to be undefined.
5309 @cindex @code{ifne} directive
5310 @item .ifne @var{absolute expression}
5311 Assembles the following section of code if the argument is not equal to zero
5312 (in other words, this is equivalent to @code{.if}).
5314 @cindex @code{ifnes} directive
5315 @item .ifnes @var{string1},@var{string2}
5316 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
5317 following section of code if the two strings are not the same.
5321 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
5323 @cindex @code{incbin} directive
5324 @cindex binary files, including
5325 The @code{incbin} directive includes @var{file} verbatim at the current
5326 location. You can control the search paths used with the @samp{-I} command-line
5327 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5330 The @var{skip} argument skips a number of bytes from the start of the
5331 @var{file}. The @var{count} argument indicates the maximum number of bytes to
5332 read. Note that the data is not aligned in any way, so it is the user's
5333 responsibility to make sure that proper alignment is provided both before and
5334 after the @code{incbin} directive.
5337 @section @code{.include "@var{file}"}
5339 @cindex @code{include} directive
5340 @cindex supporting files, including
5341 @cindex files, including
5342 This directive provides a way to include supporting files at specified
5343 points in your source program. The code from @var{file} is assembled as
5344 if it followed the point of the @code{.include}; when the end of the
5345 included file is reached, assembly of the original file continues. You
5346 can control the search paths used with the @samp{-I} command-line option
5347 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5351 @section @code{.int @var{expressions}}
5353 @cindex @code{int} directive
5354 @cindex integers, 32-bit
5355 Expect zero or more @var{expressions}, of any section, separated by commas.
5356 For each expression, emit a number that, at run time, is the value of that
5357 expression. The byte order and bit size of the number depends on what kind
5358 of target the assembly is for.
5362 On most forms of the H8/300, @code{.int} emits 16-bit
5363 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
5370 @section @code{.internal @var{names}}
5372 @cindex @code{internal} directive
5374 This is one of the ELF visibility directives. The other two are
5375 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
5376 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5378 This directive overrides the named symbols default visibility (which is set by
5379 their binding: local, global or weak). The directive sets the visibility to
5380 @code{internal} which means that the symbols are considered to be @code{hidden}
5381 (i.e., not visible to other components), and that some extra, processor specific
5382 processing must also be performed upon the symbols as well.
5386 @section @code{.irp @var{symbol},@var{values}}@dots{}
5388 @cindex @code{irp} directive
5389 Evaluate a sequence of statements assigning different values to @var{symbol}.
5390 The sequence of statements starts at the @code{.irp} directive, and is
5391 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
5392 set to @var{value}, and the sequence of statements is assembled. If no
5393 @var{value} is listed, the sequence of statements is assembled once, with
5394 @var{symbol} set to the null string. To refer to @var{symbol} within the
5395 sequence of statements, use @var{\symbol}.
5397 For example, assembling
5405 is equivalent to assembling
5413 For some caveats with the spelling of @var{symbol}, see also @ref{Macro}.
5416 @section @code{.irpc @var{symbol},@var{values}}@dots{}
5418 @cindex @code{irpc} directive
5419 Evaluate a sequence of statements assigning different values to @var{symbol}.
5420 The sequence of statements starts at the @code{.irpc} directive, and is
5421 terminated by an @code{.endr} directive. For each character in @var{value},
5422 @var{symbol} is set to the character, and the sequence of statements is
5423 assembled. If no @var{value} is listed, the sequence of statements is
5424 assembled once, with @var{symbol} set to the null string. To refer to
5425 @var{symbol} within the sequence of statements, use @var{\symbol}.
5427 For example, assembling
5435 is equivalent to assembling
5443 For some caveats with the spelling of @var{symbol}, see also the discussion
5447 @section @code{.lcomm @var{symbol} , @var{length}}
5449 @cindex @code{lcomm} directive
5450 @cindex local common symbols
5451 @cindex symbols, local common
5452 Reserve @var{length} (an absolute expression) bytes for a local common
5453 denoted by @var{symbol}. The section and value of @var{symbol} are
5454 those of the new local common. The addresses are allocated in the bss
5455 section, so that at run-time the bytes start off zeroed. @var{Symbol}
5456 is not declared global (@pxref{Global,,@code{.global}}), so is normally
5457 not visible to @code{@value{LD}}.
5460 Some targets permit a third argument to be used with @code{.lcomm}. This
5461 argument specifies the desired alignment of the symbol in the bss section.
5465 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
5466 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
5470 @section @code{.lflags}
5472 @cindex @code{lflags} directive (ignored)
5473 @command{@value{AS}} accepts this directive, for compatibility with other
5474 assemblers, but ignores it.
5476 @ifclear no-line-dir
5478 @section @code{.line @var{line-number}}
5480 @cindex @code{line} directive
5481 @cindex logical line number
5483 Change the logical line number. @var{line-number} must be an absolute
5484 expression. The next line has that logical line number. Therefore any other
5485 statements on the current line (after a statement separator character) are
5486 reported as on logical line number @var{line-number} @minus{} 1. One day
5487 @command{@value{AS}} will no longer support this directive: it is recognized only
5488 for compatibility with existing assembler programs.
5491 Even though this is a directive associated with the @code{a.out} or
5492 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
5493 when producing COFF output, and treats @samp{.line} as though it
5494 were the COFF @samp{.ln} @emph{if} it is found outside a
5495 @code{.def}/@code{.endef} pair.
5497 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
5498 used by compilers to generate auxiliary symbol information for
5503 @section @code{.linkonce [@var{type}]}
5505 @cindex @code{linkonce} directive
5506 @cindex common sections
5507 Mark the current section so that the linker only includes a single copy of it.
5508 This may be used to include the same section in several different object files,
5509 but ensure that the linker will only include it once in the final output file.
5510 The @code{.linkonce} pseudo-op must be used for each instance of the section.
5511 Duplicate sections are detected based on the section name, so it should be
5514 This directive is only supported by a few object file formats; as of this
5515 writing, the only object file format which supports it is the Portable
5516 Executable format used on Windows NT.
5518 The @var{type} argument is optional. If specified, it must be one of the
5519 following strings. For example:
5523 Not all types may be supported on all object file formats.
5527 Silently discard duplicate sections. This is the default.
5530 Warn if there are duplicate sections, but still keep only one copy.
5533 Warn if any of the duplicates have different sizes.
5536 Warn if any of the duplicates do not have exactly the same contents.
5540 @section @code{.list}
5542 @cindex @code{list} directive
5543 @cindex listing control, turning on
5544 Control (in conjunction with the @code{.nolist} directive) whether or
5545 not assembly listings are generated. These two directives maintain an
5546 internal counter (which is zero initially). @code{.list} increments the
5547 counter, and @code{.nolist} decrements it. Assembly listings are
5548 generated whenever the counter is greater than zero.
5550 By default, listings are disabled. When you enable them (with the
5551 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
5552 the initial value of the listing counter is one.
5555 @section @code{.ln @var{line-number}}
5557 @cindex @code{ln} directive
5558 @ifclear no-line-dir
5559 @samp{.ln} is a synonym for @samp{.line}.
5562 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
5563 must be an absolute expression. The next line has that logical
5564 line number, so any other statements on the current line (after a
5565 statement separator character @code{;}) are reported as on logical
5566 line number @var{line-number} @minus{} 1.
5569 This directive is accepted, but ignored, when @command{@value{AS}} is
5570 configured for @code{b.out}; its effect is only associated with COFF
5576 @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]}
5577 @cindex @code{loc} directive
5578 When emitting DWARF2 line number information,
5579 the @code{.loc} directive will add a row to the @code{.debug_line} line
5580 number matrix corresponding to the immediately following assembly
5581 instruction. The @var{fileno}, @var{lineno}, and optional @var{column}
5582 arguments will be applied to the @code{.debug_line} state machine before
5585 The @var{options} are a sequence of the following tokens in any order:
5589 This option will set the @code{basic_block} register in the
5590 @code{.debug_line} state machine to @code{true}.
5593 This option will set the @code{prologue_end} register in the
5594 @code{.debug_line} state machine to @code{true}.
5596 @item epilogue_begin
5597 This option will set the @code{epilogue_begin} register in the
5598 @code{.debug_line} state machine to @code{true}.
5600 @item is_stmt @var{value}
5601 This option will set the @code{is_stmt} register in the
5602 @code{.debug_line} state machine to @code{value}, which must be
5605 @item isa @var{value}
5606 This directive will set the @code{isa} register in the @code{.debug_line}
5607 state machine to @var{value}, which must be an unsigned integer.
5609 @item discriminator @var{value}
5610 This directive will set the @code{discriminator} register in the @code{.debug_line}
5611 state machine to @var{value}, which must be an unsigned integer.
5615 @node Loc_mark_labels
5616 @section @code{.loc_mark_labels @var{enable}}
5617 @cindex @code{loc_mark_labels} directive
5618 When emitting DWARF2 line number information,
5619 the @code{.loc_mark_labels} directive makes the assembler emit an entry
5620 to the @code{.debug_line} line number matrix with the @code{basic_block}
5621 register in the state machine set whenever a code label is seen.
5622 The @var{enable} argument should be either 1 or 0, to enable or disable
5623 this function respectively.
5627 @section @code{.local @var{names}}
5629 @cindex @code{local} directive
5630 This directive, which is available for ELF targets, marks each symbol in
5631 the comma-separated list of @code{names} as a local symbol so that it
5632 will not be externally visible. If the symbols do not already exist,
5633 they will be created.
5635 For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not
5636 accept an alignment argument, which is the case for most ELF targets,
5637 the @code{.local} directive can be used in combination with @code{.comm}
5638 (@pxref{Comm}) to define aligned local common data.
5642 @section @code{.long @var{expressions}}
5644 @cindex @code{long} directive
5645 @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}.
5648 @c no one seems to know what this is for or whether this description is
5649 @c what it really ought to do
5651 @section @code{.lsym @var{symbol}, @var{expression}}
5653 @cindex @code{lsym} directive
5654 @cindex symbol, not referenced in assembly
5655 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
5656 the hash table, ensuring it cannot be referenced by name during the
5657 rest of the assembly. This sets the attributes of the symbol to be
5658 the same as the expression value:
5660 @var{other} = @var{descriptor} = 0
5661 @var{type} = @r{(section of @var{expression})}
5662 @var{value} = @var{expression}
5665 The new symbol is not flagged as external.
5669 @section @code{.macro}
5672 The commands @code{.macro} and @code{.endm} allow you to define macros that
5673 generate assembly output. For example, this definition specifies a macro
5674 @code{sum} that puts a sequence of numbers into memory:
5677 .macro sum from=0, to=5
5686 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
5698 @item .macro @var{macname}
5699 @itemx .macro @var{macname} @var{macargs} @dots{}
5700 @cindex @code{macro} directive
5701 Begin the definition of a macro called @var{macname}. If your macro
5702 definition requires arguments, specify their names after the macro name,
5703 separated by commas or spaces. You can qualify the macro argument to
5704 indicate whether all invocations must specify a non-blank value (through
5705 @samp{:@code{req}}), or whether it takes all of the remaining arguments
5706 (through @samp{:@code{vararg}}). You can supply a default value for any
5707 macro argument by following the name with @samp{=@var{deflt}}. You
5708 cannot define two macros with the same @var{macname} unless it has been
5709 subject to the @code{.purgem} directive (@pxref{Purgem}) between the two
5710 definitions. For example, these are all valid @code{.macro} statements:
5714 Begin the definition of a macro called @code{comm}, which takes no
5717 @item .macro plus1 p, p1
5718 @itemx .macro plus1 p p1
5719 Either statement begins the definition of a macro called @code{plus1},
5720 which takes two arguments; within the macro definition, write
5721 @samp{\p} or @samp{\p1} to evaluate the arguments.
5723 @item .macro reserve_str p1=0 p2
5724 Begin the definition of a macro called @code{reserve_str}, with two
5725 arguments. The first argument has a default value, but not the second.
5726 After the definition is complete, you can call the macro either as
5727 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
5728 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
5729 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
5730 @samp{0}, and @samp{\p2} evaluating to @var{b}).
5732 @item .macro m p1:req, p2=0, p3:vararg
5733 Begin the definition of a macro called @code{m}, with at least three
5734 arguments. The first argument must always have a value specified, but
5735 not the second, which instead has a default value. The third formal
5736 will get assigned all remaining arguments specified at invocation time.
5738 When you call a macro, you can specify the argument values either by
5739 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
5740 @samp{sum to=17, from=9}.
5744 Note that since each of the @var{macargs} can be an identifier exactly
5745 as any other one permitted by the target architecture, there may be
5746 occasional problems if the target hand-crafts special meanings to certain
5747 characters when they occur in a special position. For example, if the colon
5748 (@code{:}) is generally permitted to be part of a symbol name, but the
5749 architecture specific code special-cases it when occurring as the final
5750 character of a symbol (to denote a label), then the macro parameter
5751 replacement code will have no way of knowing that and consider the whole
5752 construct (including the colon) an identifier, and check only this
5753 identifier for being the subject to parameter substitution. So for example
5754 this macro definition:
5762 might not work as expected. Invoking @samp{label foo} might not create a label
5763 called @samp{foo} but instead just insert the text @samp{\l:} into the
5764 assembler source, probably generating an error about an unrecognised
5767 Similarly problems might occur with the period character (@samp{.})
5768 which is often allowed inside opcode names (and hence identifier names). So
5769 for example constructing a macro to build an opcode from a base name and a
5770 length specifier like this:
5773 .macro opcode base length
5778 and invoking it as @samp{opcode store l} will not create a @samp{store.l}
5779 instruction but instead generate some kind of error as the assembler tries to
5780 interpret the text @samp{\base.\length}.
5782 There are several possible ways around this problem:
5785 @item Insert white space
5786 If it is possible to use white space characters then this is the simplest
5795 @item Use @samp{\()}
5796 The string @samp{\()} can be used to separate the end of a macro argument from
5797 the following text. eg:
5800 .macro opcode base length
5805 @item Use the alternate macro syntax mode
5806 In the alternative macro syntax mode the ampersand character (@samp{&}) can be
5807 used as a separator. eg:
5817 Note: this problem of correctly identifying string parameters to pseudo ops
5818 also applies to the identifiers used in @code{.irp} (@pxref{Irp})
5819 and @code{.irpc} (@pxref{Irpc}) as well.
5822 @cindex @code{endm} directive
5823 Mark the end of a macro definition.
5826 @cindex @code{exitm} directive
5827 Exit early from the current macro definition.
5829 @cindex number of macros executed
5830 @cindex macros, count executed
5832 @command{@value{AS}} maintains a counter of how many macros it has
5833 executed in this pseudo-variable; you can copy that number to your
5834 output with @samp{\@@}, but @emph{only within a macro definition}.
5836 @item LOCAL @var{name} [ , @dots{} ]
5837 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
5838 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
5839 @xref{Altmacro,,@code{.altmacro}}.
5843 @section @code{.mri @var{val}}
5845 @cindex @code{mri} directive
5846 @cindex MRI mode, temporarily
5847 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
5848 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
5849 affects code assembled until the next @code{.mri} directive, or until the end
5850 of the file. @xref{M, MRI mode, MRI mode}.
5853 @section @code{.noaltmacro}
5854 Disable alternate macro mode. @xref{Altmacro}.
5857 @section @code{.nolist}
5859 @cindex @code{nolist} directive
5860 @cindex listing control, turning off
5861 Control (in conjunction with the @code{.list} directive) whether or
5862 not assembly listings are generated. These two directives maintain an
5863 internal counter (which is zero initially). @code{.list} increments the
5864 counter, and @code{.nolist} decrements it. Assembly listings are
5865 generated whenever the counter is greater than zero.
5868 @section @code{.octa @var{bignums}}
5870 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
5871 @cindex @code{octa} directive
5872 @cindex integer, 16-byte
5873 @cindex sixteen byte integer
5874 This directive expects zero or more bignums, separated by commas. For each
5875 bignum, it emits a 16-byte integer.
5877 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
5878 hence @emph{octa}-word for 16 bytes.
5881 @section @code{.offset @var{loc}}
5883 @cindex @code{offset} directive
5884 Set the location counter to @var{loc} in the absolute section. @var{loc} must
5885 be an absolute expression. This directive may be useful for defining
5886 symbols with absolute values. Do not confuse it with the @code{.org}
5890 @section @code{.org @var{new-lc} , @var{fill}}
5892 @cindex @code{org} directive
5893 @cindex location counter, advancing
5894 @cindex advancing location counter
5895 @cindex current address, advancing
5896 Advance the location counter of the current section to
5897 @var{new-lc}. @var{new-lc} is either an absolute expression or an
5898 expression with the same section as the current subsection. That is,
5899 you can't use @code{.org} to cross sections: if @var{new-lc} has the
5900 wrong section, the @code{.org} directive is ignored. To be compatible
5901 with former assemblers, if the section of @var{new-lc} is absolute,
5902 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
5903 is the same as the current subsection.
5905 @code{.org} may only increase the location counter, or leave it
5906 unchanged; you cannot use @code{.org} to move the location counter
5909 @c double negative used below "not undefined" because this is a specific
5910 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
5911 @c section. doc@cygnus.com 18feb91
5912 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
5913 may not be undefined. If you really detest this restriction we eagerly await
5914 a chance to share your improved assembler.
5916 Beware that the origin is relative to the start of the section, not
5917 to the start of the subsection. This is compatible with other
5918 people's assemblers.
5920 When the location counter (of the current subsection) is advanced, the
5921 intervening bytes are filled with @var{fill} which should be an
5922 absolute expression. If the comma and @var{fill} are omitted,
5923 @var{fill} defaults to zero.
5926 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
5928 @cindex padding the location counter given a power of two
5929 @cindex @code{p2align} directive
5930 Pad the location counter (in the current subsection) to a particular
5931 storage boundary. The first expression (which must be absolute) is the
5932 number of low-order zero bits the location counter must have after
5933 advancement. For example @samp{.p2align 3} advances the location
5934 counter until it a multiple of 8. If the location counter is already a
5935 multiple of 8, no change is needed.
5937 The second expression (also absolute) gives the fill value to be stored in the
5938 padding bytes. It (and the comma) may be omitted. If it is omitted, the
5939 padding bytes are normally zero. However, on some systems, if the section is
5940 marked as containing code and the fill value is omitted, the space is filled
5941 with no-op instructions.
5943 The third expression is also absolute, and is also optional. If it is present,
5944 it is the maximum number of bytes that should be skipped by this alignment
5945 directive. If doing the alignment would require skipping more bytes than the
5946 specified maximum, then the alignment is not done at all. You can omit the
5947 fill value (the second argument) entirely by simply using two commas after the
5948 required alignment; this can be useful if you want the alignment to be filled
5949 with no-op instructions when appropriate.
5951 @cindex @code{p2alignw} directive
5952 @cindex @code{p2alignl} directive
5953 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5954 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5955 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5956 fill pattern as a four byte longword value. For example, @code{.p2alignw
5957 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5958 filled in with the value 0x368d (the exact placement of the bytes depends upon
5959 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5964 @section @code{.popsection}
5966 @cindex @code{popsection} directive
5967 @cindex Section Stack
5968 This is one of the ELF section stack manipulation directives. The others are
5969 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5970 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5973 This directive replaces the current section (and subsection) with the top
5974 section (and subsection) on the section stack. This section is popped off the
5980 @section @code{.previous}
5982 @cindex @code{previous} directive
5983 @cindex Section Stack
5984 This is one of the ELF section stack manipulation directives. The others are
5985 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5986 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5987 (@pxref{PopSection}).
5989 This directive swaps the current section (and subsection) with most recently
5990 referenced section/subsection pair prior to this one. Multiple
5991 @code{.previous} directives in a row will flip between two sections (and their
5992 subsections). For example:
6004 Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
6010 # Now in section A subsection 1
6014 # Now in section B subsection 0
6017 # Now in section B subsection 1
6020 # Now in section B subsection 0
6024 Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
6025 section B and 0x9abc into subsection 1 of section B.
6027 In terms of the section stack, this directive swaps the current section with
6028 the top section on the section stack.
6032 @section @code{.print @var{string}}
6034 @cindex @code{print} directive
6035 @command{@value{AS}} will print @var{string} on the standard output during
6036 assembly. You must put @var{string} in double quotes.
6040 @section @code{.protected @var{names}}
6042 @cindex @code{protected} directive
6044 This is one of the ELF visibility directives. The other two are
6045 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
6047 This directive overrides the named symbols default visibility (which is set by
6048 their binding: local, global or weak). The directive sets the visibility to
6049 @code{protected} which means that any references to the symbols from within the
6050 components that defines them must be resolved to the definition in that
6051 component, even if a definition in another component would normally preempt
6056 @section @code{.psize @var{lines} , @var{columns}}
6058 @cindex @code{psize} directive
6059 @cindex listing control: paper size
6060 @cindex paper size, for listings
6061 Use this directive to declare the number of lines---and, optionally, the
6062 number of columns---to use for each page, when generating listings.
6064 If you do not use @code{.psize}, listings use a default line-count
6065 of 60. You may omit the comma and @var{columns} specification; the
6066 default width is 200 columns.
6068 @command{@value{AS}} generates formfeeds whenever the specified number of
6069 lines is exceeded (or whenever you explicitly request one, using
6072 If you specify @var{lines} as @code{0}, no formfeeds are generated save
6073 those explicitly specified with @code{.eject}.
6076 @section @code{.purgem @var{name}}
6078 @cindex @code{purgem} directive
6079 Undefine the macro @var{name}, so that later uses of the string will not be
6080 expanded. @xref{Macro}.
6084 @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]}
6086 @cindex @code{pushsection} directive
6087 @cindex Section Stack
6088 This is one of the ELF section stack manipulation directives. The others are
6089 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
6090 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6093 This directive pushes the current section (and subsection) onto the
6094 top of the section stack, and then replaces the current section and
6095 subsection with @code{name} and @code{subsection}. The optional
6096 @code{flags}, @code{type} and @code{arguments} are treated the same
6097 as in the @code{.section} (@pxref{Section}) directive.
6101 @section @code{.quad @var{bignums}}
6103 @cindex @code{quad} directive
6104 @code{.quad} expects zero or more bignums, separated by commas. For
6105 each bignum, it emits
6107 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
6108 warning message; and just takes the lowest order 8 bytes of the bignum.
6109 @cindex eight-byte integer
6110 @cindex integer, 8-byte
6112 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
6113 hence @emph{quad}-word for 8 bytes.
6116 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
6117 warning message; and just takes the lowest order 16 bytes of the bignum.
6118 @cindex sixteen-byte integer
6119 @cindex integer, 16-byte
6123 @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
6125 @cindex @code{reloc} directive
6126 Generate a relocation at @var{offset} of type @var{reloc_name} with value
6127 @var{expression}. If @var{offset} is a number, the relocation is generated in
6128 the current section. If @var{offset} is an expression that resolves to a
6129 symbol plus offset, the relocation is generated in the given symbol's section.
6130 @var{expression}, if present, must resolve to a symbol plus addend or to an
6131 absolute value, but note that not all targets support an addend. e.g. ELF REL
6132 targets such as i386 store an addend in the section contents rather than in the
6133 relocation. This low level interface does not support addends stored in the
6137 @section @code{.rept @var{count}}
6139 @cindex @code{rept} directive
6140 Repeat the sequence of lines between the @code{.rept} directive and the next
6141 @code{.endr} directive @var{count} times.
6143 For example, assembling
6151 is equivalent to assembling
6160 @section @code{.sbttl "@var{subheading}"}
6162 @cindex @code{sbttl} directive
6163 @cindex subtitles for listings
6164 @cindex listing control: subtitle
6165 Use @var{subheading} as the title (third line, immediately after the
6166 title line) when generating assembly listings.
6168 This directive affects subsequent pages, as well as the current page if
6169 it appears within ten lines of the top of a page.
6173 @section @code{.scl @var{class}}
6175 @cindex @code{scl} directive
6176 @cindex symbol storage class (COFF)
6177 @cindex COFF symbol storage class
6178 Set the storage-class value for a symbol. This directive may only be
6179 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
6180 whether a symbol is static or external, or it may record further
6181 symbolic debugging information.
6184 The @samp{.scl} directive is primarily associated with COFF output; when
6185 configured to generate @code{b.out} output format, @command{@value{AS}}
6186 accepts this directive but ignores it.
6192 @section @code{.section @var{name}}
6194 @cindex named section
6195 Use the @code{.section} directive to assemble the following code into a section
6198 This directive is only supported for targets that actually support arbitrarily
6199 named sections; on @code{a.out} targets, for example, it is not accepted, even
6200 with a standard @code{a.out} section name.
6204 @c only print the extra heading if both COFF and ELF are set
6205 @subheading COFF Version
6208 @cindex @code{section} directive (COFF version)
6209 For COFF targets, the @code{.section} directive is used in one of the following
6213 .section @var{name}[, "@var{flags}"]
6214 .section @var{name}[, @var{subsection}]
6217 If the optional argument is quoted, it is taken as flags to use for the
6218 section. Each flag is a single character. The following flags are recognized:
6221 bss section (uninitialized data)
6223 section is not loaded
6229 exclude section from linking
6235 shared section (meaningful for PE targets)
6237 ignored. (For compatibility with the ELF version)
6239 section is not readable (meaningful for PE targets)
6241 single-digit power-of-two section alignment (GNU extension)
6244 If no flags are specified, the default flags depend upon the section name. If
6245 the section name is not recognized, the default will be for the section to be
6246 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
6247 from the section, rather than adding them, so if they are used on their own it
6248 will be as if no flags had been specified at all.
6250 If the optional argument to the @code{.section} directive is not quoted, it is
6251 taken as a subsection number (@pxref{Sub-Sections}).
6256 @c only print the extra heading if both COFF and ELF are set
6257 @subheading ELF Version
6260 @cindex Section Stack
6261 This is one of the ELF section stack manipulation directives. The others are
6262 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
6263 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
6264 @code{.previous} (@pxref{Previous}).
6266 @cindex @code{section} directive (ELF version)
6267 For ELF targets, the @code{.section} directive is used like this:
6270 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]]
6273 @anchor{Section Name Substitutions}
6274 @kindex --sectname-subst
6275 @cindex section name substitution
6276 If the @samp{--sectname-subst} command-line option is provided, the @var{name}
6277 argument may contain a substitution sequence. Only @code{%S} is supported
6278 at the moment, and substitutes the current section name. For example:
6281 .macro exception_code
6282 .section %S.exception
6283 [exception code here]
6298 The two @code{exception_code} invocations above would create the
6299 @code{.text.exception} and @code{.init.exception} sections respectively.
6300 This is useful e.g. to discriminate between anciliary sections that are
6301 tied to setup code to be discarded after use from anciliary sections that
6302 need to stay resident without having to define multiple @code{exception_code}
6303 macros just for that purpose.
6305 The optional @var{flags} argument is a quoted string which may contain any
6306 combination of the following characters:
6309 section is allocatable
6311 section is excluded from executable and shared library.
6315 section is executable
6317 section is mergeable
6319 section contains zero terminated strings
6321 section is a member of a section group
6323 section is used for thread-local-storage
6325 section is a member of the previously-current section's group, if any
6328 The optional @var{type} argument may contain one of the following constants:
6331 section contains data
6333 section does not contain data (i.e., section only occupies space)
6335 section contains data which is used by things other than the program
6337 section contains an array of pointers to init functions
6339 section contains an array of pointers to finish functions
6340 @item @@preinit_array
6341 section contains an array of pointers to pre-init functions
6344 Many targets only support the first three section types.
6346 Note on targets where the @code{@@} character is the start of a comment (eg
6347 ARM) then another character is used instead. For example the ARM port uses the
6350 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
6351 be specified as well as an extra argument---@var{entsize}---like this:
6354 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
6357 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
6358 constants, each @var{entsize} octets long. Sections with both @code{M} and
6359 @code{S} must contain zero terminated strings where each character is
6360 @var{entsize} bytes long. The linker may remove duplicates within sections with
6361 the same name, same entity size and same flags. @var{entsize} must be an
6362 absolute expression. For sections with both @code{M} and @code{S}, a string
6363 which is a suffix of a larger string is considered a duplicate. Thus
6364 @code{"def"} will be merged with @code{"abcdef"}; A reference to the first
6365 @code{"def"} will be changed to a reference to @code{"abcdef"+3}.
6367 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
6368 be present along with an additional field like this:
6371 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
6374 The @var{GroupName} field specifies the name of the section group to which this
6375 particular section belongs. The optional linkage field can contain:
6378 indicates that only one copy of this section should be retained
6383 Note: if both the @var{M} and @var{G} flags are present then the fields for
6384 the Merge flag should come first, like this:
6387 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
6390 If @var{flags} contains the @code{?} symbol then it may not also contain the
6391 @code{G} symbol and the @var{GroupName} or @var{linkage} fields should not be
6392 present. Instead, @code{?} says to consider the section that's current before
6393 this directive. If that section used @code{G}, then the new section will use
6394 @code{G} with those same @var{GroupName} and @var{linkage} fields implicitly.
6395 If not, then the @code{?} symbol has no effect.
6397 If no flags are specified, the default flags depend upon the section name. If
6398 the section name is not recognized, the default will be for the section to have
6399 none of the above flags: it will not be allocated in memory, nor writable, nor
6400 executable. The section will contain data.
6402 For ELF targets, the assembler supports another type of @code{.section}
6403 directive for compatibility with the Solaris assembler:
6406 .section "@var{name}"[, @var{flags}...]
6409 Note that the section name is quoted. There may be a sequence of comma
6413 section is allocatable
6417 section is executable
6419 section is excluded from executable and shared library.
6421 section is used for thread local storage
6424 This directive replaces the current section and subsection. See the
6425 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
6426 some examples of how this directive and the other section stack directives
6432 @section @code{.set @var{symbol}, @var{expression}}
6434 @cindex @code{set} directive
6435 @cindex symbol value, setting
6436 Set the value of @var{symbol} to @var{expression}. This
6437 changes @var{symbol}'s value and type to conform to
6438 @var{expression}. If @var{symbol} was flagged as external, it remains
6439 flagged (@pxref{Symbol Attributes}).
6441 You may @code{.set} a symbol many times in the same assembly provided that the
6442 values given to the symbol are constants. Values that are based on expressions
6443 involving other symbols are allowed, but some targets may restrict this to only
6444 being done once per assembly. This is because those targets do not set the
6445 addresses of symbols at assembly time, but rather delay the assignment until a
6446 final link is performed. This allows the linker a chance to change the code in
6447 the files, changing the location of, and the relative distance between, various
6450 If you @code{.set} a global symbol, the value stored in the object
6451 file is the last value stored into it.
6454 On Z80 @code{set} is a real instruction, use
6455 @samp{@var{symbol} defl @var{expression}} instead.
6459 @section @code{.short @var{expressions}}
6461 @cindex @code{short} directive
6463 @code{.short} is normally the same as @samp{.word}.
6464 @xref{Word,,@code{.word}}.
6466 In some configurations, however, @code{.short} and @code{.word} generate
6467 numbers of different lengths. @xref{Machine Dependencies}.
6471 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
6474 This expects zero or more @var{expressions}, and emits
6475 a 16 bit number for each.
6480 @section @code{.single @var{flonums}}
6482 @cindex @code{single} directive
6483 @cindex floating point numbers (single)
6484 This directive assembles zero or more flonums, separated by commas. It
6485 has the same effect as @code{.float}.
6487 The exact kind of floating point numbers emitted depends on how
6488 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
6492 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
6493 numbers in @sc{ieee} format.
6499 @section @code{.size}
6501 This directive is used to set the size associated with a symbol.
6505 @c only print the extra heading if both COFF and ELF are set
6506 @subheading COFF Version
6509 @cindex @code{size} directive (COFF version)
6510 For COFF targets, the @code{.size} directive is only permitted inside
6511 @code{.def}/@code{.endef} pairs. It is used like this:
6514 .size @var{expression}
6518 @samp{.size} is only meaningful when generating COFF format output; when
6519 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6526 @c only print the extra heading if both COFF and ELF are set
6527 @subheading ELF Version
6530 @cindex @code{size} directive (ELF version)
6531 For ELF targets, the @code{.size} directive is used like this:
6534 .size @var{name} , @var{expression}
6537 This directive sets the size associated with a symbol @var{name}.
6538 The size in bytes is computed from @var{expression} which can make use of label
6539 arithmetic. This directive is typically used to set the size of function
6544 @ifclear no-space-dir
6546 @section @code{.skip @var{size} , @var{fill}}
6548 @cindex @code{skip} directive
6549 @cindex filling memory
6550 This directive emits @var{size} bytes, each of value @var{fill}. Both
6551 @var{size} and @var{fill} are absolute expressions. If the comma and
6552 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
6557 @section @code{.sleb128 @var{expressions}}
6559 @cindex @code{sleb128} directive
6560 @var{sleb128} stands for ``signed little endian base 128.'' This is a
6561 compact, variable length representation of numbers used by the DWARF
6562 symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}.
6564 @ifclear no-space-dir
6566 @section @code{.space @var{size} , @var{fill}}
6568 @cindex @code{space} directive
6569 @cindex filling memory
6570 This directive emits @var{size} bytes, each of value @var{fill}. Both
6571 @var{size} and @var{fill} are absolute expressions. If the comma
6572 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
6577 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
6578 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
6579 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
6580 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
6588 @section @code{.stabd, .stabn, .stabs}
6590 @cindex symbolic debuggers, information for
6591 @cindex @code{stab@var{x}} directives
6592 There are three directives that begin @samp{.stab}.
6593 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
6594 The symbols are not entered in the @command{@value{AS}} hash table: they
6595 cannot be referenced elsewhere in the source file.
6596 Up to five fields are required:
6600 This is the symbol's name. It may contain any character except
6601 @samp{\000}, so is more general than ordinary symbol names. Some
6602 debuggers used to code arbitrarily complex structures into symbol names
6606 An absolute expression. The symbol's type is set to the low 8 bits of
6607 this expression. Any bit pattern is permitted, but @code{@value{LD}}
6608 and debuggers choke on silly bit patterns.
6611 An absolute expression. The symbol's ``other'' attribute is set to the
6612 low 8 bits of this expression.
6615 An absolute expression. The symbol's descriptor is set to the low 16
6616 bits of this expression.
6619 An absolute expression which becomes the symbol's value.
6622 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
6623 or @code{.stabs} statement, the symbol has probably already been created;
6624 you get a half-formed symbol in your object file. This is
6625 compatible with earlier assemblers!
6628 @cindex @code{stabd} directive
6629 @item .stabd @var{type} , @var{other} , @var{desc}
6631 The ``name'' of the symbol generated is not even an empty string.
6632 It is a null pointer, for compatibility. Older assemblers used a
6633 null pointer so they didn't waste space in object files with empty
6636 The symbol's value is set to the location counter,
6637 relocatably. When your program is linked, the value of this symbol
6638 is the address of the location counter when the @code{.stabd} was
6641 @cindex @code{stabn} directive
6642 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
6643 The name of the symbol is set to the empty string @code{""}.
6645 @cindex @code{stabs} directive
6646 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
6647 All five fields are specified.
6653 @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
6654 "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
6656 @cindex string, copying to object file
6657 @cindex string8, copying to object file
6658 @cindex string16, copying to object file
6659 @cindex string32, copying to object file
6660 @cindex string64, copying to object file
6661 @cindex @code{string} directive
6662 @cindex @code{string8} directive
6663 @cindex @code{string16} directive
6664 @cindex @code{string32} directive
6665 @cindex @code{string64} directive
6667 Copy the characters in @var{str} to the object file. You may specify more than
6668 one string to copy, separated by commas. Unless otherwise specified for a
6669 particular machine, the assembler marks the end of each string with a 0 byte.
6670 You can use any of the escape sequences described in @ref{Strings,,Strings}.
6672 The variants @code{string16}, @code{string32} and @code{string64} differ from
6673 the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
6674 copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
6675 are stored in target endianness byte order.
6681 .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
6682 .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
6687 @section @code{.struct @var{expression}}
6689 @cindex @code{struct} directive
6690 Switch to the absolute section, and set the section offset to @var{expression},
6691 which must be an absolute expression. You might use this as follows:
6700 This would define the symbol @code{field1} to have the value 0, the symbol
6701 @code{field2} to have the value 4, and the symbol @code{field3} to have the
6702 value 8. Assembly would be left in the absolute section, and you would need to
6703 use a @code{.section} directive of some sort to change to some other section
6704 before further assembly.
6708 @section @code{.subsection @var{name}}
6710 @cindex @code{subsection} directive
6711 @cindex Section Stack
6712 This is one of the ELF section stack manipulation directives. The others are
6713 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
6714 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6717 This directive replaces the current subsection with @code{name}. The current
6718 section is not changed. The replaced subsection is put onto the section stack
6719 in place of the then current top of stack subsection.
6724 @section @code{.symver}
6725 @cindex @code{symver} directive
6726 @cindex symbol versioning
6727 @cindex versions of symbols
6728 Use the @code{.symver} directive to bind symbols to specific version nodes
6729 within a source file. This is only supported on ELF platforms, and is
6730 typically used when assembling files to be linked into a shared library.
6731 There are cases where it may make sense to use this in objects to be bound
6732 into an application itself so as to override a versioned symbol from a
6735 For ELF targets, the @code{.symver} directive can be used like this:
6737 .symver @var{name}, @var{name2@@nodename}
6739 If the symbol @var{name} is defined within the file
6740 being assembled, the @code{.symver} directive effectively creates a symbol
6741 alias with the name @var{name2@@nodename}, and in fact the main reason that we
6742 just don't try and create a regular alias is that the @var{@@} character isn't
6743 permitted in symbol names. The @var{name2} part of the name is the actual name
6744 of the symbol by which it will be externally referenced. The name @var{name}
6745 itself is merely a name of convenience that is used so that it is possible to
6746 have definitions for multiple versions of a function within a single source
6747 file, and so that the compiler can unambiguously know which version of a
6748 function is being mentioned. The @var{nodename} portion of the alias should be
6749 the name of a node specified in the version script supplied to the linker when
6750 building a shared library. If you are attempting to override a versioned
6751 symbol from a shared library, then @var{nodename} should correspond to the
6752 nodename of the symbol you are trying to override.
6754 If the symbol @var{name} is not defined within the file being assembled, all
6755 references to @var{name} will be changed to @var{name2@@nodename}. If no
6756 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
6759 Another usage of the @code{.symver} directive is:
6761 .symver @var{name}, @var{name2@@@@nodename}
6763 In this case, the symbol @var{name} must exist and be defined within
6764 the file being assembled. It is similar to @var{name2@@nodename}. The
6765 difference is @var{name2@@@@nodename} will also be used to resolve
6766 references to @var{name2} by the linker.
6768 The third usage of the @code{.symver} directive is:
6770 .symver @var{name}, @var{name2@@@@@@nodename}
6772 When @var{name} is not defined within the
6773 file being assembled, it is treated as @var{name2@@nodename}. When
6774 @var{name} is defined within the file being assembled, the symbol
6775 name, @var{name}, will be changed to @var{name2@@@@nodename}.
6780 @section @code{.tag @var{structname}}
6782 @cindex COFF structure debugging
6783 @cindex structure debugging, COFF
6784 @cindex @code{tag} directive
6785 This directive is generated by compilers to include auxiliary debugging
6786 information in the symbol table. It is only permitted inside
6787 @code{.def}/@code{.endef} pairs. Tags are used to link structure
6788 definitions in the symbol table with instances of those structures.
6791 @samp{.tag} is only used when generating COFF format output; when
6792 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6798 @section @code{.text @var{subsection}}
6800 @cindex @code{text} directive
6801 Tells @command{@value{AS}} to assemble the following statements onto the end of
6802 the text subsection numbered @var{subsection}, which is an absolute
6803 expression. If @var{subsection} is omitted, subsection number zero
6807 @section @code{.title "@var{heading}"}
6809 @cindex @code{title} directive
6810 @cindex listing control: title line
6811 Use @var{heading} as the title (second line, immediately after the
6812 source file name and pagenumber) when generating assembly listings.
6814 This directive affects subsequent pages, as well as the current page if
6815 it appears within ten lines of the top of a page.
6819 @section @code{.type}
6821 This directive is used to set the type of a symbol.
6825 @c only print the extra heading if both COFF and ELF are set
6826 @subheading COFF Version
6829 @cindex COFF symbol type
6830 @cindex symbol type, COFF
6831 @cindex @code{type} directive (COFF version)
6832 For COFF targets, this directive is permitted only within
6833 @code{.def}/@code{.endef} pairs. It is used like this:
6839 This records the integer @var{int} as the type attribute of a symbol table
6843 @samp{.type} is associated only with COFF format output; when
6844 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
6845 directive but ignores it.
6851 @c only print the extra heading if both COFF and ELF are set
6852 @subheading ELF Version
6855 @cindex ELF symbol type
6856 @cindex symbol type, ELF
6857 @cindex @code{type} directive (ELF version)
6858 For ELF targets, the @code{.type} directive is used like this:
6861 .type @var{name} , @var{type description}
6864 This sets the type of symbol @var{name} to be either a
6865 function symbol or an object symbol. There are five different syntaxes
6866 supported for the @var{type description} field, in order to provide
6867 compatibility with various other assemblers.
6869 Because some of the characters used in these syntaxes (such as @samp{@@} and
6870 @samp{#}) are comment characters for some architectures, some of the syntaxes
6871 below do not work on all architectures. The first variant will be accepted by
6872 the GNU assembler on all architectures so that variant should be used for
6873 maximum portability, if you do not need to assemble your code with other
6876 The syntaxes supported are:
6879 .type <name> STT_<TYPE_IN_UPPER_CASE>
6880 .type <name>,#<type>
6881 .type <name>,@@<type>
6882 .type <name>,%<type>
6883 .type <name>,"<type>"
6886 The types supported are:
6891 Mark the symbol as being a function name.
6894 @itemx gnu_indirect_function
6895 Mark the symbol as an indirect function when evaluated during reloc
6896 processing. (This is only supported on assemblers targeting GNU systems).
6900 Mark the symbol as being a data object.
6904 Mark the symbol as being a thead-local data object.
6908 Mark the symbol as being a common data object.
6912 Does not mark the symbol in any way. It is supported just for completeness.
6914 @item gnu_unique_object
6915 Marks the symbol as being a globally unique data object. The dynamic linker
6916 will make sure that in the entire process there is just one symbol with this
6917 name and type in use. (This is only supported on assemblers targeting GNU
6922 Note: Some targets support extra types in addition to those listed above.
6928 @section @code{.uleb128 @var{expressions}}
6930 @cindex @code{uleb128} directive
6931 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
6932 compact, variable length representation of numbers used by the DWARF
6933 symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}.
6937 @section @code{.val @var{addr}}
6939 @cindex @code{val} directive
6940 @cindex COFF value attribute
6941 @cindex value attribute, COFF
6942 This directive, permitted only within @code{.def}/@code{.endef} pairs,
6943 records the address @var{addr} as the value attribute of a symbol table
6947 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
6948 configured for @code{b.out}, it accepts this directive but ignores it.
6954 @section @code{.version "@var{string}"}
6956 @cindex @code{version} directive
6957 This directive creates a @code{.note} section and places into it an ELF
6958 formatted note of type NT_VERSION. The note's name is set to @code{string}.
6963 @section @code{.vtable_entry @var{table}, @var{offset}}
6965 @cindex @code{vtable_entry} directive
6966 This directive finds or creates a symbol @code{table} and creates a
6967 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
6970 @section @code{.vtable_inherit @var{child}, @var{parent}}
6972 @cindex @code{vtable_inherit} directive
6973 This directive finds the symbol @code{child} and finds or creates the symbol
6974 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
6975 parent whose addend is the value of the child symbol. As a special case the
6976 parent name of @code{0} is treated as referring to the @code{*ABS*} section.
6980 @section @code{.warning "@var{string}"}
6981 @cindex warning directive
6982 Similar to the directive @code{.error}
6983 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
6986 @section @code{.weak @var{names}}
6988 @cindex @code{weak} directive
6989 This directive sets the weak attribute on the comma separated list of symbol
6990 @code{names}. If the symbols do not already exist, they will be created.
6992 On COFF targets other than PE, weak symbols are a GNU extension. This
6993 directive sets the weak attribute on the comma separated list of symbol
6994 @code{names}. If the symbols do not already exist, they will be created.
6996 On the PE target, weak symbols are supported natively as weak aliases.
6997 When a weak symbol is created that is not an alias, GAS creates an
6998 alternate symbol to hold the default value.
7001 @section @code{.weakref @var{alias}, @var{target}}
7003 @cindex @code{weakref} directive
7004 This directive creates an alias to the target symbol that enables the symbol to
7005 be referenced with weak-symbol semantics, but without actually making it weak.
7006 If direct references or definitions of the symbol are present, then the symbol
7007 will not be weak, but if all references to it are through weak references, the
7008 symbol will be marked as weak in the symbol table.
7010 The effect is equivalent to moving all references to the alias to a separate
7011 assembly source file, renaming the alias to the symbol in it, declaring the
7012 symbol as weak there, and running a reloadable link to merge the object files
7013 resulting from the assembly of the new source file and the old source file that
7014 had the references to the alias removed.
7016 The alias itself never makes to the symbol table, and is entirely handled
7017 within the assembler.
7020 @section @code{.word @var{expressions}}
7022 @cindex @code{word} directive
7023 This directive expects zero or more @var{expressions}, of any section,
7024 separated by commas.
7027 For each expression, @command{@value{AS}} emits a 32-bit number.
7030 For each expression, @command{@value{AS}} emits a 16-bit number.
7035 The size of the number emitted, and its byte order,
7036 depend on what target computer the assembly is for.
7039 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
7040 @c happen---32-bit addressability, period; no long/short jumps.
7041 @ifset DIFF-TBL-KLUGE
7042 @cindex difference tables altered
7043 @cindex altered difference tables
7045 @emph{Warning: Special Treatment to support Compilers}
7049 Machines with a 32-bit address space, but that do less than 32-bit
7050 addressing, require the following special treatment. If the machine of
7051 interest to you does 32-bit addressing (or doesn't require it;
7052 @pxref{Machine Dependencies}), you can ignore this issue.
7055 In order to assemble compiler output into something that works,
7056 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
7057 Directives of the form @samp{.word sym1-sym2} are often emitted by
7058 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
7059 directive of the form @samp{.word sym1-sym2}, and the difference between
7060 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
7061 creates a @dfn{secondary jump table}, immediately before the next label.
7062 This secondary jump table is preceded by a short-jump to the
7063 first byte after the secondary table. This short-jump prevents the flow
7064 of control from accidentally falling into the new table. Inside the
7065 table is a long-jump to @code{sym2}. The original @samp{.word}
7066 contains @code{sym1} minus the address of the long-jump to
7069 If there were several occurrences of @samp{.word sym1-sym2} before the
7070 secondary jump table, all of them are adjusted. If there was a
7071 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
7072 long-jump to @code{sym4} is included in the secondary jump table,
7073 and the @code{.word} directives are adjusted to contain @code{sym3}
7074 minus the address of the long-jump to @code{sym4}; and so on, for as many
7075 entries in the original jump table as necessary.
7078 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
7079 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
7080 assembly language programmers.
7083 @c end DIFF-TBL-KLUGE
7085 @ifclear no-space-dir
7087 @section @code{.zero @var{size}}
7089 @cindex @code{zero} directive
7090 @cindex filling memory with zero bytes
7091 This directive emits @var{size} 0-valued bytes. @var{size} must be an absolute
7092 expression. This directive is actually an alias for the @samp{.skip} directive
7093 so in can take an optional second argument of the value to store in the bytes
7094 instead of zero. Using @samp{.zero} in this way would be confusing however.
7098 @section Deprecated Directives
7100 @cindex deprecated directives
7101 @cindex obsolescent directives
7102 One day these directives won't work.
7103 They are included for compatibility with older assemblers.
7110 @node Object Attributes
7111 @chapter Object Attributes
7112 @cindex object attributes
7114 @command{@value{AS}} assembles source files written for a specific architecture
7115 into object files for that architecture. But not all object files are alike.
7116 Many architectures support incompatible variations. For instance, floating
7117 point arguments might be passed in floating point registers if the object file
7118 requires hardware floating point support---or floating point arguments might be
7119 passed in integer registers if the object file supports processors with no
7120 hardware floating point unit. Or, if two objects are built for different
7121 generations of the same architecture, the combination may require the
7122 newer generation at run-time.
7124 This information is useful during and after linking. At link time,
7125 @command{@value{LD}} can warn about incompatible object files. After link
7126 time, tools like @command{gdb} can use it to process the linked file
7129 Compatibility information is recorded as a series of object attributes. Each
7130 attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
7131 string, and indicates who sets the meaning of the tag. The tag is an integer,
7132 and indicates what property the attribute describes. The value may be a string
7133 or an integer, and indicates how the property affects this object. Missing
7134 attributes are the same as attributes with a zero value or empty string value.
7136 Object attributes were developed as part of the ABI for the ARM Architecture.
7137 The file format is documented in @cite{ELF for the ARM Architecture}.
7140 * GNU Object Attributes:: @sc{gnu} Object Attributes
7141 * Defining New Object Attributes:: Defining New Object Attributes
7144 @node GNU Object Attributes
7145 @section @sc{gnu} Object Attributes
7147 The @code{.gnu_attribute} directive records an object attribute
7148 with vendor @samp{gnu}.
7150 Except for @samp{Tag_compatibility}, which has both an integer and a string for
7151 its value, @sc{gnu} attributes have a string value if the tag number is odd and
7152 an integer value if the tag number is even. The second bit (@code{@var{tag} &
7153 2} is set for architecture-independent attributes and clear for
7154 architecture-dependent ones.
7156 @subsection Common @sc{gnu} attributes
7158 These attributes are valid on all architectures.
7161 @item Tag_compatibility (32)
7162 The compatibility attribute takes an integer flag value and a vendor name. If
7163 the flag value is 0, the file is compatible with other toolchains. If it is 1,
7164 then the file is only compatible with the named toolchain. If it is greater
7165 than 1, the file can only be processed by other toolchains under some private
7166 arrangement indicated by the flag value and the vendor name.
7169 @subsection MIPS Attributes
7172 @item Tag_GNU_MIPS_ABI_FP (4)
7173 The floating-point ABI used by this object file. The value will be:
7177 0 for files not affected by the floating-point ABI.
7179 1 for files using the hardware floating-point ABI with a standard
7180 double-precision FPU.
7182 2 for files using the hardware floating-point ABI with a single-precision FPU.
7184 3 for files using the software floating-point ABI.
7186 4 for files using the deprecated hardware floating-point ABI which used 64-bit
7187 floating-point registers, 32-bit general-purpose registers and increased the
7188 number of callee-saved floating-point registers.
7190 5 for files using the hardware floating-point ABI with a double-precision FPU
7191 with either 32-bit or 64-bit floating-point registers and 32-bit
7192 general-purpose registers.
7194 6 for files using the hardware floating-point ABI with 64-bit floating-point
7195 registers and 32-bit general-purpose registers.
7197 7 for files using the hardware floating-point ABI with 64-bit floating-point
7198 registers, 32-bit general-purpose registers and a rule that forbids the
7199 direct use of odd-numbered single-precision floating-point registers.
7203 @subsection PowerPC Attributes
7206 @item Tag_GNU_Power_ABI_FP (4)
7207 The floating-point ABI used by this object file. The value will be:
7211 0 for files not affected by the floating-point ABI.
7213 1 for files using double-precision hardware floating-point ABI.
7215 2 for files using the software floating-point ABI.
7217 3 for files using single-precision hardware floating-point ABI.
7220 @item Tag_GNU_Power_ABI_Vector (8)
7221 The vector ABI used by this object file. The value will be:
7225 0 for files not affected by the vector ABI.
7227 1 for files using general purpose registers to pass vectors.
7229 2 for files using AltiVec registers to pass vectors.
7231 3 for files using SPE registers to pass vectors.
7235 @subsection IBM z Systems Attributes
7238 @item Tag_GNU_S390_ABI_Vector (8)
7239 The vector ABI used by this object file. The value will be:
7243 0 for files not affected by the vector ABI.
7245 1 for files using software vector ABI.
7247 2 for files using hardware vector ABI.
7251 @node Defining New Object Attributes
7252 @section Defining New Object Attributes
7254 If you want to define a new @sc{gnu} object attribute, here are the places you
7255 will need to modify. New attributes should be discussed on the @samp{binutils}
7260 This manual, which is the official register of attributes.
7262 The header for your architecture @file{include/elf}, to define the tag.
7264 The @file{bfd} support file for your architecture, to merge the attribute
7265 and issue any appropriate link warnings.
7267 Test cases in @file{ld/testsuite} for merging and link warnings.
7269 @file{binutils/readelf.c} to display your attribute.
7271 GCC, if you want the compiler to mark the attribute automatically.
7277 @node Machine Dependencies
7278 @chapter Machine Dependent Features
7280 @cindex machine dependencies
7281 The machine instruction sets are (almost by definition) different on
7282 each machine where @command{@value{AS}} runs. Floating point representations
7283 vary as well, and @command{@value{AS}} often supports a few additional
7284 directives or command-line options for compatibility with other
7285 assemblers on a particular platform. Finally, some versions of
7286 @command{@value{AS}} support special pseudo-instructions for branch
7289 This chapter discusses most of these differences, though it does not
7290 include details on any machine's instruction set. For details on that
7291 subject, see the hardware manufacturer's manual.
7295 * AArch64-Dependent:: AArch64 Dependent Features
7298 * Alpha-Dependent:: Alpha Dependent Features
7301 * ARC-Dependent:: ARC Dependent Features
7304 * ARM-Dependent:: ARM Dependent Features
7307 * AVR-Dependent:: AVR Dependent Features
7310 * Blackfin-Dependent:: Blackfin Dependent Features
7313 * CR16-Dependent:: CR16 Dependent Features
7316 * CRIS-Dependent:: CRIS Dependent Features
7319 * D10V-Dependent:: D10V Dependent Features
7322 * D30V-Dependent:: D30V Dependent Features
7325 * Epiphany-Dependent:: EPIPHANY Dependent Features
7328 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7331 * HPPA-Dependent:: HPPA Dependent Features
7334 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
7337 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
7340 * i860-Dependent:: Intel 80860 Dependent Features
7343 * i960-Dependent:: Intel 80960 Dependent Features
7346 * IA-64-Dependent:: Intel IA-64 Dependent Features
7349 * IP2K-Dependent:: IP2K Dependent Features
7352 * LM32-Dependent:: LM32 Dependent Features
7355 * M32C-Dependent:: M32C Dependent Features
7358 * M32R-Dependent:: M32R Dependent Features
7361 * M68K-Dependent:: M680x0 Dependent Features
7364 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
7367 * Meta-Dependent :: Meta Dependent Features
7370 * MicroBlaze-Dependent:: MICROBLAZE Dependent Features
7373 * MIPS-Dependent:: MIPS Dependent Features
7376 * MMIX-Dependent:: MMIX Dependent Features
7379 * MSP430-Dependent:: MSP430 Dependent Features
7382 * NDS32-Dependent:: Andes NDS32 Dependent Features
7385 * NiosII-Dependent:: Altera Nios II Dependent Features
7388 * NS32K-Dependent:: NS32K Dependent Features
7391 * PDP-11-Dependent:: PDP-11 Dependent Features
7394 * PJ-Dependent:: picoJava Dependent Features
7397 * PPC-Dependent:: PowerPC Dependent Features
7400 * RL78-Dependent:: RL78 Dependent Features
7403 * RX-Dependent:: RX Dependent Features
7406 * S/390-Dependent:: IBM S/390 Dependent Features
7409 * SCORE-Dependent:: SCORE Dependent Features
7412 * SH-Dependent:: Renesas / SuperH SH Dependent Features
7413 * SH64-Dependent:: SuperH SH64 Dependent Features
7416 * Sparc-Dependent:: SPARC Dependent Features
7419 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
7422 * TIC6X-Dependent :: TI TMS320C6x Dependent Features
7425 * TILE-Gx-Dependent :: Tilera TILE-Gx Dependent Features
7428 * TILEPro-Dependent :: Tilera TILEPro Dependent Features
7431 * V850-Dependent:: V850 Dependent Features
7434 * Vax-Dependent:: VAX Dependent Features
7437 * Visium-Dependent:: Visium Dependent Features
7440 * XGATE-Dependent:: XGATE Features
7443 * XSTORMY16-Dependent:: XStormy16 Dependent Features
7446 * Xtensa-Dependent:: Xtensa Dependent Features
7449 * Z80-Dependent:: Z80 Dependent Features
7452 * Z8000-Dependent:: Z8000 Dependent Features
7459 @c The following major nodes are *sections* in the GENERIC version, *chapters*
7460 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
7461 @c peculiarity: to preserve cross-references, there must be a node called
7462 @c "Machine Dependencies". Hence the conditional nodenames in each
7463 @c major node below. Node defaulting in makeinfo requires adjacency of
7464 @c node and sectioning commands; hence the repetition of @chapter BLAH
7465 @c in both conditional blocks.
7468 @include c-aarch64.texi
7472 @include c-alpha.texi
7488 @include c-bfin.texi
7492 @include c-cr16.texi
7496 @include c-cris.texi
7501 @node Machine Dependencies
7502 @chapter Machine Dependent Features
7504 The machine instruction sets are different on each Renesas chip family,
7505 and there are also some syntax differences among the families. This
7506 chapter describes the specific @command{@value{AS}} features for each
7510 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7511 * SH-Dependent:: Renesas SH Dependent Features
7518 @include c-d10v.texi
7522 @include c-d30v.texi
7526 @include c-epiphany.texi
7530 @include c-h8300.texi
7534 @include c-hppa.texi
7538 @include c-i370.texi
7542 @include c-i386.texi
7546 @include c-i860.texi
7550 @include c-i960.texi
7554 @include c-ia64.texi
7558 @include c-ip2k.texi
7562 @include c-lm32.texi
7566 @include c-m32c.texi
7570 @include c-m32r.texi
7574 @include c-m68k.texi
7578 @include c-m68hc11.texi
7582 @include c-metag.texi
7586 @include c-microblaze.texi
7590 @include c-mips.texi
7594 @include c-mmix.texi
7598 @include c-msp430.texi
7602 @include c-nds32.texi
7606 @include c-nios2.texi
7610 @include c-ns32k.texi
7614 @include c-pdp11.texi
7626 @include c-rl78.texi
7634 @include c-s390.texi
7638 @include c-score.texi
7643 @include c-sh64.texi
7647 @include c-sparc.texi
7651 @include c-tic54x.texi
7655 @include c-tic6x.texi
7659 @include c-tilegx.texi
7663 @include c-tilepro.texi
7667 @include c-v850.texi
7675 @include c-visium.texi
7679 @include c-xgate.texi
7683 @include c-xstormy16.texi
7687 @include c-xtensa.texi
7699 @c reverse effect of @down at top of generic Machine-Dep chapter
7703 @node Reporting Bugs
7704 @chapter Reporting Bugs
7705 @cindex bugs in assembler
7706 @cindex reporting bugs in assembler
7708 Your bug reports play an essential role in making @command{@value{AS}} reliable.
7710 Reporting a bug may help you by bringing a solution to your problem, or it may
7711 not. But in any case the principal function of a bug report is to help the
7712 entire community by making the next version of @command{@value{AS}} work better.
7713 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
7715 In order for a bug report to serve its purpose, you must include the
7716 information that enables us to fix the bug.
7719 * Bug Criteria:: Have you found a bug?
7720 * Bug Reporting:: How to report bugs
7724 @section Have You Found a Bug?
7725 @cindex bug criteria
7727 If you are not sure whether you have found a bug, here are some guidelines:
7730 @cindex fatal signal
7731 @cindex assembler crash
7732 @cindex crash of assembler
7734 If the assembler gets a fatal signal, for any input whatever, that is a
7735 @command{@value{AS}} bug. Reliable assemblers never crash.
7737 @cindex error on valid input
7739 If @command{@value{AS}} produces an error message for valid input, that is a bug.
7741 @cindex invalid input
7743 If @command{@value{AS}} does not produce an error message for invalid input, that
7744 is a bug. However, you should note that your idea of ``invalid input'' might
7745 be our idea of ``an extension'' or ``support for traditional practice''.
7748 If you are an experienced user of assemblers, your suggestions for improvement
7749 of @command{@value{AS}} are welcome in any case.
7753 @section How to Report Bugs
7755 @cindex assembler bugs, reporting
7757 A number of companies and individuals offer support for @sc{gnu} products. If
7758 you obtained @command{@value{AS}} from a support organization, we recommend you
7759 contact that organization first.
7761 You can find contact information for many support companies and
7762 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
7766 In any event, we also recommend that you send bug reports for @command{@value{AS}}
7770 The fundamental principle of reporting bugs usefully is this:
7771 @strong{report all the facts}. If you are not sure whether to state a
7772 fact or leave it out, state it!
7774 Often people omit facts because they think they know what causes the problem
7775 and assume that some details do not matter. Thus, you might assume that the
7776 name of a symbol you use in an example does not matter. Well, probably it does
7777 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
7778 happens to fetch from the location where that name is stored in memory;
7779 perhaps, if the name were different, the contents of that location would fool
7780 the assembler into doing the right thing despite the bug. Play it safe and
7781 give a specific, complete example. That is the easiest thing for you to do,
7782 and the most helpful.
7784 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
7785 it is new to us. Therefore, always write your bug reports on the assumption
7786 that the bug has not been reported previously.
7788 Sometimes people give a few sketchy facts and ask, ``Does this ring a
7789 bell?'' This cannot help us fix a bug, so it is basically useless. We
7790 respond by asking for enough details to enable us to investigate.
7791 You might as well expedite matters by sending them to begin with.
7793 To enable us to fix the bug, you should include all these things:
7797 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
7798 it with the @samp{--version} argument.
7800 Without this, we will not know whether there is any point in looking for
7801 the bug in the current version of @command{@value{AS}}.
7804 Any patches you may have applied to the @command{@value{AS}} source.
7807 The type of machine you are using, and the operating system name and
7811 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
7815 The command arguments you gave the assembler to assemble your example and
7816 observe the bug. To guarantee you will not omit something important, list them
7817 all. A copy of the Makefile (or the output from make) is sufficient.
7819 If we were to try to guess the arguments, we would probably guess wrong
7820 and then we might not encounter the bug.
7823 A complete input file that will reproduce the bug. If the bug is observed when
7824 the assembler is invoked via a compiler, send the assembler source, not the
7825 high level language source. Most compilers will produce the assembler source
7826 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
7827 the options @samp{-v --save-temps}; this will save the assembler source in a
7828 file with an extension of @file{.s}, and also show you exactly how
7829 @command{@value{AS}} is being run.
7832 A description of what behavior you observe that you believe is
7833 incorrect. For example, ``It gets a fatal signal.''
7835 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
7836 will certainly notice it. But if the bug is incorrect output, we might not
7837 notice unless it is glaringly wrong. You might as well not give us a chance to
7840 Even if the problem you experience is a fatal signal, you should still say so
7841 explicitly. Suppose something strange is going on, such as, your copy of
7842 @command{@value{AS}} is out of sync, or you have encountered a bug in the C
7843 library on your system. (This has happened!) Your copy might crash and ours
7844 would not. If you told us to expect a crash, then when ours fails to crash, we
7845 would know that the bug was not happening for us. If you had not told us to
7846 expect a crash, then we would not be able to draw any conclusion from our
7850 If you wish to suggest changes to the @command{@value{AS}} source, send us context
7851 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
7852 option. Always send diffs from the old file to the new file. If you even
7853 discuss something in the @command{@value{AS}} source, refer to it by context, not
7856 The line numbers in our development sources will not match those in your
7857 sources. Your line numbers would convey no useful information to us.
7860 Here are some things that are not necessary:
7864 A description of the envelope of the bug.
7866 Often people who encounter a bug spend a lot of time investigating
7867 which changes to the input file will make the bug go away and which
7868 changes will not affect it.
7870 This is often time consuming and not very useful, because the way we
7871 will find the bug is by running a single example under the debugger
7872 with breakpoints, not by pure deduction from a series of examples.
7873 We recommend that you save your time for something else.
7875 Of course, if you can find a simpler example to report @emph{instead}
7876 of the original one, that is a convenience for us. Errors in the
7877 output will be easier to spot, running under the debugger will take
7878 less time, and so on.
7880 However, simplification is not vital; if you do not want to do this,
7881 report the bug anyway and send us the entire test case you used.
7884 A patch for the bug.
7886 A patch for the bug does help us if it is a good one. But do not omit
7887 the necessary information, such as the test case, on the assumption that
7888 a patch is all we need. We might see problems with your patch and decide
7889 to fix the problem another way, or we might not understand it at all.
7891 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
7892 construct an example that will make the program follow a certain path through
7893 the code. If you do not send us the example, we will not be able to construct
7894 one, so we will not be able to verify that the bug is fixed.
7896 And if we cannot understand what bug you are trying to fix, or why your
7897 patch should be an improvement, we will not install it. A test case will
7898 help us to understand.
7901 A guess about what the bug is or what it depends on.
7903 Such guesses are usually wrong. Even we cannot guess right about such
7904 things without first using the debugger to find the facts.
7907 @node Acknowledgements
7908 @chapter Acknowledgements
7910 If you have contributed to GAS and your name isn't listed here,
7911 it is not meant as a slight. We just don't know about it. Send mail to the
7912 maintainer, and we'll correct the situation. Currently
7914 the maintainer is Nick Clifton (email address @code{nickc@@redhat.com}).
7916 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
7919 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
7920 information and the 68k series machines, most of the preprocessing pass, and
7921 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
7923 K. Richard Pixley maintained GAS for a while, adding various enhancements and
7924 many bug fixes, including merging support for several processors, breaking GAS
7925 up to handle multiple object file format back ends (including heavy rewrite,
7926 testing, an integration of the coff and b.out back ends), adding configuration
7927 including heavy testing and verification of cross assemblers and file splits
7928 and renaming, converted GAS to strictly ANSI C including full prototypes, added
7929 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
7930 port (including considerable amounts of reverse engineering), a SPARC opcode
7931 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
7932 assertions and made them work, much other reorganization, cleanup, and lint.
7934 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
7935 in format-specific I/O modules.
7937 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
7938 has done much work with it since.
7940 The Intel 80386 machine description was written by Eliot Dresselhaus.
7942 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
7944 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
7945 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
7947 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
7948 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
7949 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
7950 support a.out format.
7952 Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
7953 tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
7954 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
7955 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
7958 John Gilmore built the AMD 29000 support, added @code{.include} support, and
7959 simplified the configuration of which versions accept which directives. He
7960 updated the 68k machine description so that Motorola's opcodes always produced
7961 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
7962 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
7963 cross-compilation support, and one bug in relaxation that took a week and
7964 required the proverbial one-bit fix.
7966 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
7967 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
7968 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
7969 PowerPC assembler, and made a few other minor patches.
7971 Steve Chamberlain made GAS able to generate listings.
7973 Hewlett-Packard contributed support for the HP9000/300.
7975 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
7976 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
7977 formats). This work was supported by both the Center for Software Science at
7978 the University of Utah and Cygnus Support.
7980 Support for ELF format files has been worked on by Mark Eichin of Cygnus
7981 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
7982 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
7983 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
7984 and some initial 64-bit support).
7986 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
7988 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
7989 support for openVMS/Alpha.
7991 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
7994 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
7995 Inc.@: added support for Xtensa processors.
7997 Several engineers at Cygnus Support have also provided many small bug fixes and
7998 configuration enhancements.
8000 Jon Beniston added support for the Lattice Mico32 architecture.
8002 Many others have contributed large or small bugfixes and enhancements. If
8003 you have contributed significant work and are not mentioned on this list, and
8004 want to be, let us know. Some of the history has been lost; we are not
8005 intentionally leaving anyone out.
8007 @node GNU Free Documentation License
8008 @appendix GNU Free Documentation License
8012 @unnumbered AS Index
projects / deliverable / binutils-gdb.git / blob