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}]
238 [@b{-o} @var{objfile}] [@b{-R}]
239 [@b{--hash-size}=@var{NUM}] [@b{--reduce-memory-overheads}]
241 [@b{-v}] [@b{-version}] [@b{--version}]
242 [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}] [@b{-w}] [@b{-x}]
243 [@b{-Z}] [@b{@@@var{FILE}}]
244 [@b{--sectname-subst}] [@b{--size-check=[error|warning]}]
245 [@b{--target-help}] [@var{target-options}]
246 [@b{--}|@var{files} @dots{}]
248 @c Target dependent options are listed below. Keep the list sorted.
249 @c Add an empty line for separation.
252 @emph{Target AArch64 options:}
254 [@b{-mabi}=@var{ABI}]
258 @emph{Target Alpha options:}
260 [@b{-mdebug} | @b{-no-mdebug}]
261 [@b{-replace} | @b{-noreplace}]
262 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
263 [@b{-F}] [@b{-32addr}]
267 @emph{Target ARC options:}
273 @emph{Target ARM options:}
274 @c Don't document the deprecated options
275 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
276 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
277 [@b{-mfpu}=@var{floating-point-format}]
278 [@b{-mfloat-abi}=@var{abi}]
279 [@b{-meabi}=@var{ver}]
282 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
283 @b{-mapcs-reentrant}]
284 [@b{-mthumb-interwork}] [@b{-k}]
288 @emph{Target Blackfin options:}
289 [@b{-mcpu}=@var{processor}[-@var{sirevision}]]
296 @emph{Target CRIS options:}
297 [@b{--underscore} | @b{--no-underscore}]
299 [@b{--emulation=criself} | @b{--emulation=crisaout}]
300 [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}]
301 @c Deprecated -- deliberately not documented.
306 @emph{Target D10V options:}
311 @emph{Target D30V options:}
312 [@b{-O}|@b{-n}|@b{-N}]
316 @emph{Target EPIPHANY options:}
317 [@b{-mepiphany}|@b{-mepiphany16}]
321 @emph{Target H8/300 options:}
325 @c HPPA has no machine-dependent assembler options (yet).
329 @emph{Target i386 options:}
330 [@b{--32}|@b{--x32}|@b{--64}] [@b{-n}]
331 [@b{-march}=@var{CPU}[+@var{EXTENSION}@dots{}]] [@b{-mtune}=@var{CPU}]
335 @emph{Target i960 options:}
336 @c see md_parse_option in tc-i960.c
337 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
339 [@b{-b}] [@b{-no-relax}]
343 @emph{Target IA-64 options:}
344 [@b{-mconstant-gp}|@b{-mauto-pic}]
345 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
347 [@b{-mtune=itanium1}|@b{-mtune=itanium2}]
348 [@b{-munwind-check=warning}|@b{-munwind-check=error}]
349 [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}]
350 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
354 @emph{Target IP2K options:}
355 [@b{-mip2022}|@b{-mip2022ext}]
359 @emph{Target M32C options:}
360 [@b{-m32c}|@b{-m16c}] [-relax] [-h-tick-hex]
364 @emph{Target M32R options:}
365 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
370 @emph{Target M680X0 options:}
371 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
375 @emph{Target M68HC11 options:}
376 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}|@b{-mm9s12x}|@b{-mm9s12xg}]
377 [@b{-mshort}|@b{-mlong}]
378 [@b{-mshort-double}|@b{-mlong-double}]
379 [@b{--force-long-branches}] [@b{--short-branches}]
380 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
381 [@b{--print-opcodes}] [@b{--generate-example}]
385 @emph{Target MCORE options:}
386 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
387 [@b{-mcpu=[210|340]}]
391 @emph{Target Meta options:}
392 [@b{-mcpu=@var{cpu}}] [@b{-mfpu=@var{cpu}}] [@b{-mdsp=@var{cpu}}]
395 @emph{Target MICROBLAZE options:}
396 @c MicroBlaze has no machine-dependent assembler options.
400 @emph{Target MIPS options:}
401 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
402 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
403 [@b{-non_shared}] [@b{-xgot} [@b{-mvxworks-pic}]
404 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
405 [@b{-mfp64}] [@b{-mgp64}] [@b{-mfpxx}]
406 [@b{-modd-spreg}] [@b{-mno-odd-spreg}]
407 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
408 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
409 [@b{-mips32r3}] [@b{-mips32r5}] [@b{-mips32r6}] [@b{-mips64}] [@b{-mips64r2}]
410 [@b{-mips64r3}] [@b{-mips64r5}] [@b{-mips64r6}]
411 [@b{-construct-floats}] [@b{-no-construct-floats}]
412 [@b{-mnan=@var{encoding}}]
413 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
414 [@b{-mips16}] [@b{-no-mips16}]
415 [@b{-mmicromips}] [@b{-mno-micromips}]
416 [@b{-msmartmips}] [@b{-mno-smartmips}]
417 [@b{-mips3d}] [@b{-no-mips3d}]
418 [@b{-mdmx}] [@b{-no-mdmx}]
419 [@b{-mdsp}] [@b{-mno-dsp}]
420 [@b{-mdspr2}] [@b{-mno-dspr2}]
421 [@b{-mmsa}] [@b{-mno-msa}]
422 [@b{-mxpa}] [@b{-mno-xpa}]
423 [@b{-mmt}] [@b{-mno-mt}]
424 [@b{-mmcu}] [@b{-mno-mcu}]
425 [@b{-minsn32}] [@b{-mno-insn32}]
426 [@b{-mfix7000}] [@b{-mno-fix7000}]
427 [@b{-mfix-rm7000}] [@b{-mno-fix-rm7000}]
428 [@b{-mfix-vr4120}] [@b{-mno-fix-vr4120}]
429 [@b{-mfix-vr4130}] [@b{-mno-fix-vr4130}]
430 [@b{-mdebug}] [@b{-no-mdebug}]
431 [@b{-mpdr}] [@b{-mno-pdr}]
435 @emph{Target MMIX options:}
436 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
437 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
438 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
439 [@b{--linker-allocated-gregs}]
443 @emph{Target Nios II options:}
444 [@b{-relax-all}] [@b{-relax-section}] [@b{-no-relax}]
449 @emph{Target NDS32 options:}
450 [@b{-EL}] [@b{-EB}] [@b{-O}] [@b{-Os}] [@b{-mcpu=@var{cpu}}]
451 [@b{-misa=@var{isa}}] [@b{-mabi=@var{abi}}] [@b{-mall-ext}]
452 [@b{-m[no-]16-bit}] [@b{-m[no-]perf-ext}] [@b{-m[no-]perf2-ext}]
453 [@b{-m[no-]string-ext}] [@b{-m[no-]dsp-ext}] [@b{-m[no-]mac}] [@b{-m[no-]div}]
454 [@b{-m[no-]audio-isa-ext}] [@b{-m[no-]fpu-sp-ext}] [@b{-m[no-]fpu-dp-ext}]
455 [@b{-m[no-]fpu-fma}] [@b{-mfpu-freg=@var{FREG}}] [@b{-mreduced-regs}]
456 [@b{-mfull-regs}] [@b{-m[no-]dx-regs}] [@b{-mpic}] [@b{-mno-relax}]
461 @emph{Target PDP11 options:}
462 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
463 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
464 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
468 @emph{Target picoJava options:}
473 @emph{Target PowerPC options:}
475 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|@b{-m403}|@b{-m405}|
476 @b{-m440}|@b{-m464}|@b{-m476}|@b{-m7400}|@b{-m7410}|@b{-m7450}|@b{-m7455}|@b{-m750cl}|@b{-mppc64}|
477 @b{-m620}|@b{-me500}|@b{-e500x2}|@b{-me500mc}|@b{-me500mc64}|@b{-me5500}|@b{-me6500}|@b{-mppc64bridge}|
478 @b{-mbooke}|@b{-mpower4}|@b{-mpwr4}|@b{-mpower5}|@b{-mpwr5}|@b{-mpwr5x}|@b{-mpower6}|@b{-mpwr6}|
479 @b{-mpower7}|@b{-mpwr7}|@b{-mpower8}|@b{-mpwr8}|@b{-ma2}|@b{-mcell}|@b{-mspe}|@b{-mtitan}|@b{-me300}|@b{-mcom}]
480 [@b{-many}] [@b{-maltivec}|@b{-mvsx}|@b{-mhtm}|@b{-mvle}]
481 [@b{-mregnames}|@b{-mno-regnames}]
482 [@b{-mrelocatable}|@b{-mrelocatable-lib}|@b{-K PIC}] [@b{-memb}]
483 [@b{-mlittle}|@b{-mlittle-endian}|@b{-le}|@b{-mbig}|@b{-mbig-endian}|@b{-be}]
484 [@b{-msolaris}|@b{-mno-solaris}]
485 [@b{-nops=@var{count}}]
489 @emph{Target RL78 options:}
491 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
495 @emph{Target RX options:}
496 [@b{-mlittle-endian}|@b{-mbig-endian}]
497 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
498 [@b{-muse-conventional-section-names}]
499 [@b{-msmall-data-limit}]
502 [@b{-mint-register=@var{number}}]
503 [@b{-mgcc-abi}|@b{-mrx-abi}]
507 @emph{Target s390 options:}
508 [@b{-m31}|@b{-m64}] [@b{-mesa}|@b{-mzarch}] [@b{-march}=@var{CPU}]
509 [@b{-mregnames}|@b{-mno-regnames}]
510 [@b{-mwarn-areg-zero}]
514 @emph{Target SCORE options:}
515 [@b{-EB}][@b{-EL}][@b{-FIXDD}][@b{-NWARN}]
516 [@b{-SCORE5}][@b{-SCORE5U}][@b{-SCORE7}][@b{-SCORE3}]
517 [@b{-march=score7}][@b{-march=score3}]
518 [@b{-USE_R1}][@b{-KPIC}][@b{-O0}][@b{-G} @var{num}][@b{-V}]
522 @emph{Target SPARC options:}
523 @c The order here is important. See c-sparc.texi.
524 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
525 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
526 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
531 @emph{Target TIC54X options:}
532 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
533 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
537 @emph{Target TIC6X options:}
538 [@b{-march=@var{arch}}] [@b{-mbig-endian}|@b{-mlittle-endian}]
539 [@b{-mdsbt}|@b{-mno-dsbt}] [@b{-mpid=no}|@b{-mpid=near}|@b{-mpid=far}]
540 [@b{-mpic}|@b{-mno-pic}]
544 @emph{Target TILE-Gx options:}
545 [@b{-m32}|@b{-m64}][@b{-EB}][@b{-EL}]
548 @c TILEPro has no machine-dependent assembler options
552 @emph{Target Visium options:}
553 [@b{-mtune=@var{arch}}]
557 @emph{Target Xtensa options:}
558 [@b{--[no-]text-section-literals}] [@b{--[no-]auto-litpools}]
559 [@b{--[no-]absolute-literals}]
560 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
561 [@b{--[no-]transform}]
562 [@b{--rename-section} @var{oldname}=@var{newname}]
563 [@b{--[no-]trampolines}]
567 @emph{Target Z80 options:}
568 [@b{-z80}] [@b{-r800}]
569 [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}]
570 [@b{ -ignore-unportable-instructions}] [@b{-Wnup}]
571 [@b{ -warn-undocumented-instructions}] [@b{-Wud}]
572 [@b{ -warn-unportable-instructions}] [@b{-Wup}]
573 [@b{ -forbid-undocumented-instructions}] [@b{-Fud}]
574 [@b{ -forbid-unportable-instructions}] [@b{-Fup}]
578 @c Z8000 has no machine-dependent assembler options
587 @include at-file.texi
590 Turn on listings, in any of a variety of ways:
594 omit false conditionals
597 omit debugging directives
600 include general information, like @value{AS} version and options passed
603 include high-level source
609 include macro expansions
612 omit forms processing
618 set the name of the listing file
621 You may combine these options; for example, use @samp{-aln} for assembly
622 listing without forms processing. The @samp{=file} option, if used, must be
623 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
626 Begin in alternate macro mode.
628 @xref{Altmacro,,@code{.altmacro}}.
631 @item --compress-debug-sections
632 Compress DWARF debug sections using zlib with SHF_COMPRESSED from the
633 ELF ABI. The resulting object file may not be compatible with older
634 linkers and object file utilities. Note if compression would make a
635 given section @emph{larger} then it is not compressed.
638 @cindex @samp{--compress-debug-sections=} option
639 @item --compress-debug-sections=none
640 @itemx --compress-debug-sections=zlib
641 @itemx --compress-debug-sections=zlib-gnu
642 @itemx --compress-debug-sections=zlib-gabi
643 These options control how DWARF debug sections are compressed.
644 @option{--compress-debug-sections=none} is equivalent to
645 @option{--nocompress-debug-sections}.
646 @option{--compress-debug-sections=zlib} and
647 @option{--compress-debug-sections=zlib-gabi} are equivalent to
648 @option{--compress-debug-sections}.
649 @option{--compress-debug-sections=zlib-gnu} compresses DWARF debug
650 sections using zlib. The debug sections are renamed to begin with
651 @samp{.zdebug}. Note if compression would make a given section
652 @emph{larger} then it is not compressed nor renamed.
656 @item --nocompress-debug-sections
657 Do not compress DWARF debug sections. This is the default.
660 Ignored. This option is accepted for script compatibility with calls to
663 @item --debug-prefix-map @var{old}=@var{new}
664 When assembling files in directory @file{@var{old}}, record debugging
665 information describing them as in @file{@var{new}} instead.
667 @item --defsym @var{sym}=@var{value}
668 Define the symbol @var{sym} to be @var{value} before assembling the input file.
669 @var{value} must be an integer constant. As in C, a leading @samp{0x}
670 indicates a hexadecimal value, and a leading @samp{0} indicates an octal
671 value. The value of the symbol can be overridden inside a source file via the
672 use of a @code{.set} pseudo-op.
675 ``fast''---skip whitespace and comment preprocessing (assume source is
680 Generate debugging information for each assembler source line using whichever
681 debug format is preferred by the target. This currently means either STABS,
685 Generate stabs debugging information for each assembler line. This
686 may help debugging assembler code, if the debugger can handle it.
689 Generate stabs debugging information for each assembler line, with GNU
690 extensions that probably only gdb can handle, and that could make other
691 debuggers crash or refuse to read your program. This
692 may help debugging assembler code. Currently the only GNU extension is
693 the location of the current working directory at assembling time.
696 Generate DWARF2 debugging information for each assembler line. This
697 may help debugging assembler code, if the debugger can handle it. Note---this
698 option is only supported by some targets, not all of them.
700 @item --gdwarf-sections
701 Instead of creating a .debug_line section, create a series of
702 .debug_line.@var{foo} sections where @var{foo} is the name of the
703 corresponding code section. For example a code section called @var{.text.func}
704 will have its dwarf line number information placed into a section called
705 @var{.debug_line.text.func}. If the code section is just called @var{.text}
706 then debug line section will still be called just @var{.debug_line} without any
709 @item --size-check=error
710 @itemx --size-check=warning
711 Issue an error or warning for invalid ELF .size directive.
714 Print a summary of the command line options and exit.
717 Print a summary of all target specific options and exit.
720 Add directory @var{dir} to the search list for @code{.include} directives.
723 Don't warn about signed overflow.
726 @ifclear DIFF-TBL-KLUGE
727 This option is accepted but has no effect on the @value{TARGET} family.
729 @ifset DIFF-TBL-KLUGE
730 Issue warnings when difference tables altered for long displacements.
735 Keep (in the symbol table) local symbols. These symbols start with
736 system-specific local label prefixes, typically @samp{.L} for ELF systems
737 or @samp{L} for traditional a.out systems.
742 @item --listing-lhs-width=@var{number}
743 Set the maximum width, in words, of the output data column for an assembler
744 listing to @var{number}.
746 @item --listing-lhs-width2=@var{number}
747 Set the maximum width, in words, of the output data column for continuation
748 lines in an assembler listing to @var{number}.
750 @item --listing-rhs-width=@var{number}
751 Set the maximum width of an input source line, as displayed in a listing, to
754 @item --listing-cont-lines=@var{number}
755 Set the maximum number of lines printed in a listing for a single line of input
758 @item -o @var{objfile}
759 Name the object-file output from @command{@value{AS}} @var{objfile}.
762 Fold the data section into the text section.
764 @item --hash-size=@var{number}
765 Set the default size of GAS's hash tables to a prime number close to
766 @var{number}. Increasing this value can reduce the length of time it takes the
767 assembler to perform its tasks, at the expense of increasing the assembler's
768 memory requirements. Similarly reducing this value can reduce the memory
769 requirements at the expense of speed.
771 @item --reduce-memory-overheads
772 This option reduces GAS's memory requirements, at the expense of making the
773 assembly processes slower. Currently this switch is a synonym for
774 @samp{--hash-size=4051}, but in the future it may have other effects as well.
777 @item --sectname-subst
778 Honor substitution sequences in section names.
780 @xref{Section Name Substitutions,,@code{.section @var{name}}}.
785 Print the maximum space (in bytes) and total time (in seconds) used by
788 @item --strip-local-absolute
789 Remove local absolute symbols from the outgoing symbol table.
793 Print the @command{as} version.
796 Print the @command{as} version and exit.
800 Suppress warning messages.
802 @item --fatal-warnings
803 Treat warnings as errors.
806 Don't suppress warning messages or treat them as errors.
815 Generate an object file even after errors.
817 @item -- | @var{files} @dots{}
818 Standard input, or source files to assemble.
826 @xref{AArch64 Options}, for the options available when @value{AS} is configured
827 for the 64-bit mode of the ARM Architecture (AArch64).
832 The following options are available when @value{AS} is configured for the
833 64-bit mode of the ARM Architecture (AArch64).
836 @include c-aarch64.texi
837 @c ended inside the included file
845 @xref{Alpha Options}, for the options available when @value{AS} is configured
846 for an Alpha processor.
851 The following options are available when @value{AS} is configured for an Alpha
855 @include c-alpha.texi
856 @c ended inside the included file
863 The following options are available when @value{AS} is configured for
868 This option selects the core processor variant.
870 Select either big-endian (-EB) or little-endian (-EL) output.
875 The following options are available when @value{AS} is configured for the ARM
879 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
880 Specify which ARM processor variant is the target.
881 @item -march=@var{architecture}[+@var{extension}@dots{}]
882 Specify which ARM architecture variant is used by the target.
883 @item -mfpu=@var{floating-point-format}
884 Select which Floating Point architecture is the target.
885 @item -mfloat-abi=@var{abi}
886 Select which floating point ABI is in use.
888 Enable Thumb only instruction decoding.
889 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
890 Select which procedure calling convention is in use.
892 Select either big-endian (-EB) or little-endian (-EL) output.
893 @item -mthumb-interwork
894 Specify that the code has been generated with interworking between Thumb and
897 Turns on CodeComposer Studio assembly syntax compatibility mode.
899 Specify that PIC code has been generated.
907 @xref{Blackfin Options}, for the options available when @value{AS} is
908 configured for the Blackfin processor family.
913 The following options are available when @value{AS} is configured for
914 the Blackfin processor family.
918 @c ended inside the included file
925 See the info pages for documentation of the CRIS-specific options.
929 The following options are available when @value{AS} is configured for
932 @cindex D10V optimization
933 @cindex optimization, D10V
935 Optimize output by parallelizing instructions.
940 The following options are available when @value{AS} is configured for a D30V
943 @cindex D30V optimization
944 @cindex optimization, D30V
946 Optimize output by parallelizing instructions.
950 Warn when nops are generated.
952 @cindex D30V nops after 32-bit multiply
954 Warn when a nop after a 32-bit multiply instruction is generated.
960 The following options are available when @value{AS} is configured for the
961 Adapteva EPIPHANY series.
964 @xref{Epiphany Options}, for the options available when @value{AS} is
965 configured for an Epiphany processor.
970 The following options are available when @value{AS} is configured for
971 an Epiphany processor.
974 @include c-epiphany.texi
975 @c ended inside the included file
983 @xref{H8/300 Options}, for the options available when @value{AS} is configured
984 for an H8/300 processor.
989 The following options are available when @value{AS} is configured for an H8/300
993 @include c-h8300.texi
994 @c ended inside the included file
1002 @xref{i386-Options}, for the options available when @value{AS} is
1003 configured for an i386 processor.
1007 @c man begin OPTIONS
1008 The following options are available when @value{AS} is configured for
1011 @c man begin INCLUDE
1012 @include c-i386.texi
1013 @c ended inside the included file
1018 @c man begin OPTIONS
1020 The following options are available when @value{AS} is configured for the
1021 Intel 80960 processor.
1024 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
1025 Specify which variant of the 960 architecture is the target.
1028 Add code to collect statistics about branches taken.
1031 Do not alter compare-and-branch instructions for long displacements;
1038 The following options are available when @value{AS} is configured for the
1044 Specifies that the extended IP2022 instructions are allowed.
1047 Restores the default behaviour, which restricts the permitted instructions to
1048 just the basic IP2022 ones.
1054 The following options are available when @value{AS} is configured for the
1055 Renesas M32C and M16C processors.
1060 Assemble M32C instructions.
1063 Assemble M16C instructions (the default).
1066 Enable support for link-time relaxations.
1069 Support H'00 style hex constants in addition to 0x00 style.
1075 The following options are available when @value{AS} is configured for the
1076 Renesas M32R (formerly Mitsubishi M32R) series.
1081 Specify which processor in the M32R family is the target. The default
1082 is normally the M32R, but this option changes it to the M32RX.
1084 @item --warn-explicit-parallel-conflicts or --Wp
1085 Produce warning messages when questionable parallel constructs are
1088 @item --no-warn-explicit-parallel-conflicts or --Wnp
1089 Do not produce warning messages when questionable parallel constructs are
1096 The following options are available when @value{AS} is configured for the
1097 Motorola 68000 series.
1102 Shorten references to undefined symbols, to one word instead of two.
1104 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
1105 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
1106 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
1107 Specify what processor in the 68000 family is the target. The default
1108 is normally the 68020, but this can be changed at configuration time.
1110 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
1111 The target machine does (or does not) have a floating-point coprocessor.
1112 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
1113 the basic 68000 is not compatible with the 68881, a combination of the
1114 two can be specified, since it's possible to do emulation of the
1115 coprocessor instructions with the main processor.
1117 @item -m68851 | -mno-68851
1118 The target machine does (or does not) have a memory-management
1119 unit coprocessor. The default is to assume an MMU for 68020 and up.
1127 @xref{Nios II Options}, for the options available when @value{AS} is configured
1128 for an Altera Nios II processor.
1132 @c man begin OPTIONS
1133 The following options are available when @value{AS} is configured for an
1134 Altera Nios II processor.
1136 @c man begin INCLUDE
1137 @include c-nios2.texi
1138 @c ended inside the included file
1144 For details about the PDP-11 machine dependent features options,
1145 see @ref{PDP-11-Options}.
1148 @item -mpic | -mno-pic
1149 Generate position-independent (or position-dependent) code. The
1150 default is @option{-mpic}.
1153 @itemx -mall-extensions
1154 Enable all instruction set extensions. This is the default.
1156 @item -mno-extensions
1157 Disable all instruction set extensions.
1159 @item -m@var{extension} | -mno-@var{extension}
1160 Enable (or disable) a particular instruction set extension.
1163 Enable the instruction set extensions supported by a particular CPU, and
1164 disable all other extensions.
1166 @item -m@var{machine}
1167 Enable the instruction set extensions supported by a particular machine
1168 model, and disable all other extensions.
1174 The following options are available when @value{AS} is configured for
1175 a picoJava processor.
1179 @cindex PJ endianness
1180 @cindex endianness, PJ
1181 @cindex big endian output, PJ
1183 Generate ``big endian'' format output.
1185 @cindex little endian output, PJ
1187 Generate ``little endian'' format output.
1193 The following options are available when @value{AS} is configured for the
1194 Motorola 68HC11 or 68HC12 series.
1198 @item -m68hc11 | -m68hc12 | -m68hcs12 | -mm9s12x | -mm9s12xg
1199 Specify what processor is the target. The default is
1200 defined by the configuration option when building the assembler.
1202 @item --xgate-ramoffset
1203 Instruct the linker to offset RAM addresses from S12X address space into
1204 XGATE address space.
1207 Specify to use the 16-bit integer ABI.
1210 Specify to use the 32-bit integer ABI.
1212 @item -mshort-double
1213 Specify to use the 32-bit double ABI.
1216 Specify to use the 64-bit double ABI.
1218 @item --force-long-branches
1219 Relative branches are turned into absolute ones. This concerns
1220 conditional branches, unconditional branches and branches to a
1223 @item -S | --short-branches
1224 Do not turn relative branches into absolute ones
1225 when the offset is out of range.
1227 @item --strict-direct-mode
1228 Do not turn the direct addressing mode into extended addressing mode
1229 when the instruction does not support direct addressing mode.
1231 @item --print-insn-syntax
1232 Print the syntax of instruction in case of error.
1234 @item --print-opcodes
1235 Print the list of instructions with syntax and then exit.
1237 @item --generate-example
1238 Print an example of instruction for each possible instruction and then exit.
1239 This option is only useful for testing @command{@value{AS}}.
1245 The following options are available when @command{@value{AS}} is configured
1246 for the SPARC architecture:
1249 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
1250 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
1251 Explicitly select a variant of the SPARC architecture.
1253 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
1254 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
1256 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
1257 UltraSPARC extensions.
1259 @item -xarch=v8plus | -xarch=v8plusa
1260 For compatibility with the Solaris v9 assembler. These options are
1261 equivalent to -Av8plus and -Av8plusa, respectively.
1264 Warn when the assembler switches to another architecture.
1269 The following options are available when @value{AS} is configured for the 'c54x
1274 Enable extended addressing mode. All addresses and relocations will assume
1275 extended addressing (usually 23 bits).
1276 @item -mcpu=@var{CPU_VERSION}
1277 Sets the CPU version being compiled for.
1278 @item -merrors-to-file @var{FILENAME}
1279 Redirect error output to a file, for broken systems which don't support such
1280 behaviour in the shell.
1285 The following options are available when @value{AS} is configured for
1290 This option sets the largest size of an object that can be referenced
1291 implicitly with the @code{gp} register. It is only accepted for targets that
1292 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
1294 @cindex MIPS endianness
1295 @cindex endianness, MIPS
1296 @cindex big endian output, MIPS
1298 Generate ``big endian'' format output.
1300 @cindex little endian output, MIPS
1302 Generate ``little endian'' format output.
1320 Generate code for a particular MIPS Instruction Set Architecture level.
1321 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
1322 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
1323 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
1324 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips32r3},
1325 @samp{-mips32r5}, @samp{-mips32r6}, @samp{-mips64}, @samp{-mips64r2},
1326 @samp{-mips64r3}, @samp{-mips64r5}, and @samp{-mips64r6} correspond to generic
1327 MIPS V, MIPS32, MIPS32 Release 2, MIPS32 Release 3, MIPS32 Release 5, MIPS32
1328 Release 6, MIPS64, MIPS64 Release 2, MIPS64 Release 3, MIPS64 Release 5, and
1329 MIPS64 Release 6 ISA processors, respectively.
1331 @item -march=@var{cpu}
1332 Generate code for a particular MIPS CPU.
1334 @item -mtune=@var{cpu}
1335 Schedule and tune for a particular MIPS CPU.
1339 Cause nops to be inserted if the read of the destination register
1340 of an mfhi or mflo instruction occurs in the following two instructions.
1343 @itemx -mno-fix-rm7000
1344 Cause nops to be inserted if a dmult or dmultu instruction is
1345 followed by a load instruction.
1349 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
1350 section instead of the standard ELF .stabs sections.
1354 Control generation of @code{.pdr} sections.
1358 The register sizes are normally inferred from the ISA and ABI, but these
1359 flags force a certain group of registers to be treated as 32 bits wide at
1360 all times. @samp{-mgp32} controls the size of general-purpose registers
1361 and @samp{-mfp32} controls the size of floating-point registers.
1365 The register sizes are normally inferred from the ISA and ABI, but these
1366 flags force a certain group of registers to be treated as 64 bits wide at
1367 all times. @samp{-mgp64} controls the size of general-purpose registers
1368 and @samp{-mfp64} controls the size of floating-point registers.
1371 The register sizes are normally inferred from the ISA and ABI, but using
1372 this flag in combination with @samp{-mabi=32} enables an ABI variant
1373 which will operate correctly with floating-point registers which are
1377 @itemx -mno-odd-spreg
1378 Enable use of floating-point operations on odd-numbered single-precision
1379 registers when supported by the ISA. @samp{-mfpxx} implies
1380 @samp{-mno-odd-spreg}, otherwise the default is @samp{-modd-spreg}.
1384 Generate code for the MIPS 16 processor. This is equivalent to putting
1385 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
1386 turns off this option.
1389 @itemx -mno-micromips
1390 Generate code for the microMIPS processor. This is equivalent to putting
1391 @code{.set micromips} at the start of the assembly file. @samp{-mno-micromips}
1392 turns off this option. This is equivalent to putting @code{.set nomicromips}
1393 at the start of the assembly file.
1396 @itemx -mno-smartmips
1397 Enables the SmartMIPS extension to the MIPS32 instruction set. This is
1398 equivalent to putting @code{.set smartmips} at the start of the assembly file.
1399 @samp{-mno-smartmips} turns off this option.
1403 Generate code for the MIPS-3D Application Specific Extension.
1404 This tells the assembler to accept MIPS-3D instructions.
1405 @samp{-no-mips3d} turns off this option.
1409 Generate code for the MDMX Application Specific Extension.
1410 This tells the assembler to accept MDMX instructions.
1411 @samp{-no-mdmx} turns off this option.
1415 Generate code for the DSP Release 1 Application Specific Extension.
1416 This tells the assembler to accept DSP Release 1 instructions.
1417 @samp{-mno-dsp} turns off this option.
1421 Generate code for the DSP Release 2 Application Specific Extension.
1422 This option implies -mdsp.
1423 This tells the assembler to accept DSP Release 2 instructions.
1424 @samp{-mno-dspr2} turns off this option.
1428 Generate code for the MIPS SIMD Architecture Extension.
1429 This tells the assembler to accept MSA instructions.
1430 @samp{-mno-msa} turns off this option.
1434 Generate code for the MIPS eXtended Physical Address (XPA) Extension.
1435 This tells the assembler to accept XPA instructions.
1436 @samp{-mno-xpa} turns off this option.
1440 Generate code for the MT Application Specific Extension.
1441 This tells the assembler to accept MT instructions.
1442 @samp{-mno-mt} turns off this option.
1446 Generate code for the MCU Application Specific Extension.
1447 This tells the assembler to accept MCU instructions.
1448 @samp{-mno-mcu} turns off this option.
1452 Only use 32-bit instruction encodings when generating code for the
1453 microMIPS processor. This option inhibits the use of any 16-bit
1454 instructions. This is equivalent to putting @code{.set insn32} at
1455 the start of the assembly file. @samp{-mno-insn32} turns off this
1456 option. This is equivalent to putting @code{.set noinsn32} at the
1457 start of the assembly file. By default @samp{-mno-insn32} is
1458 selected, allowing all instructions to be used.
1460 @item --construct-floats
1461 @itemx --no-construct-floats
1462 The @samp{--no-construct-floats} option disables the construction of
1463 double width floating point constants by loading the two halves of the
1464 value into the two single width floating point registers that make up
1465 the double width register. By default @samp{--construct-floats} is
1466 selected, allowing construction of these floating point constants.
1468 @item --relax-branch
1469 @itemx --no-relax-branch
1470 The @samp{--relax-branch} option enables the relaxation of out-of-range
1471 branches. By default @samp{--no-relax-branch} is selected, causing any
1472 out-of-range branches to produce an error.
1474 @item -mnan=@var{encoding}
1475 Select between the IEEE 754-2008 (@option{-mnan=2008}) or the legacy
1476 (@option{-mnan=legacy}) NaN encoding format. The latter is the default.
1479 @item --emulation=@var{name}
1480 This option was formerly used to switch between ELF and ECOFF output
1481 on targets like IRIX 5 that supported both. MIPS ECOFF support was
1482 removed in GAS 2.24, so the option now serves little purpose.
1483 It is retained for backwards compatibility.
1485 The available configuration names are: @samp{mipself}, @samp{mipslelf} and
1486 @samp{mipsbelf}. Choosing @samp{mipself} now has no effect, since the output
1487 is always ELF. @samp{mipslelf} and @samp{mipsbelf} select little- and
1488 big-endian output respectively, but @samp{-EL} and @samp{-EB} are now the
1489 preferred options instead.
1492 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1499 Control how to deal with multiplication overflow and division by zero.
1500 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1501 (and only work for Instruction Set Architecture level 2 and higher);
1502 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1506 When this option is used, @command{@value{AS}} will issue a warning every
1507 time it generates a nop instruction from a macro.
1512 The following options are available when @value{AS} is configured for
1518 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1519 The command line option @samp{-nojsri2bsr} can be used to disable it.
1523 Enable or disable the silicon filter behaviour. By default this is disabled.
1524 The default can be overridden by the @samp{-sifilter} command line option.
1527 Alter jump instructions for long displacements.
1529 @item -mcpu=[210|340]
1530 Select the cpu type on the target hardware. This controls which instructions
1534 Assemble for a big endian target.
1537 Assemble for a little endian target.
1546 @xref{Meta Options}, for the options available when @value{AS} is configured
1547 for a Meta processor.
1551 @c man begin OPTIONS
1552 The following options are available when @value{AS} is configured for a
1555 @c man begin INCLUDE
1556 @include c-metag.texi
1557 @c ended inside the included file
1562 @c man begin OPTIONS
1564 See the info pages for documentation of the MMIX-specific options.
1570 @xref{NDS32 Options}, for the options available when @value{AS} is configured
1571 for a NDS32 processor.
1573 @c ended inside the included file
1577 @c man begin OPTIONS
1578 The following options are available when @value{AS} is configured for a
1581 @c man begin INCLUDE
1582 @include c-nds32.texi
1583 @c ended inside the included file
1590 @xref{PowerPC-Opts}, for the options available when @value{AS} is configured
1591 for a PowerPC processor.
1595 @c man begin OPTIONS
1596 The following options are available when @value{AS} is configured for a
1599 @c man begin INCLUDE
1601 @c ended inside the included file
1606 @c man begin OPTIONS
1608 See the info pages for documentation of the RX-specific options.
1612 The following options are available when @value{AS} is configured for the s390
1618 Select the word size, either 31/32 bits or 64 bits.
1621 Select the architecture mode, either the Enterprise System
1622 Architecture (esa) or the z/Architecture mode (zarch).
1623 @item -march=@var{processor}
1624 Specify which s390 processor variant is the target, @samp{g6}, @samp{g6},
1625 @samp{z900}, @samp{z990}, @samp{z9-109}, @samp{z9-ec}, @samp{z10},
1626 @samp{z196}, @samp{zEC12}, or @samp{z13}.
1628 @itemx -mno-regnames
1629 Allow or disallow symbolic names for registers.
1630 @item -mwarn-areg-zero
1631 Warn whenever the operand for a base or index register has been specified
1632 but evaluates to zero.
1640 @xref{TIC6X Options}, for the options available when @value{AS} is configured
1641 for a TMS320C6000 processor.
1645 @c man begin OPTIONS
1646 The following options are available when @value{AS} is configured for a
1647 TMS320C6000 processor.
1649 @c man begin INCLUDE
1650 @include c-tic6x.texi
1651 @c ended inside the included file
1659 @xref{TILE-Gx Options}, for the options available when @value{AS} is configured
1660 for a TILE-Gx processor.
1664 @c man begin OPTIONS
1665 The following options are available when @value{AS} is configured for a TILE-Gx
1668 @c man begin INCLUDE
1669 @include c-tilegx.texi
1670 @c ended inside the included file
1678 @xref{Visium Options}, for the options available when @value{AS} is configured
1679 for a Visium processor.
1683 @c man begin OPTIONS
1684 The following option is available when @value{AS} is configured for a Visium
1687 @c man begin INCLUDE
1688 @include c-visium.texi
1689 @c ended inside the included file
1697 @xref{Xtensa Options}, for the options available when @value{AS} is configured
1698 for an Xtensa processor.
1702 @c man begin OPTIONS
1703 The following options are available when @value{AS} is configured for an
1706 @c man begin INCLUDE
1707 @include c-xtensa.texi
1708 @c ended inside the included file
1713 @c man begin OPTIONS
1716 The following options are available when @value{AS} is configured for
1717 a Z80 family processor.
1720 Assemble for Z80 processor.
1722 Assemble for R800 processor.
1723 @item -ignore-undocumented-instructions
1725 Assemble undocumented Z80 instructions that also work on R800 without warning.
1726 @item -ignore-unportable-instructions
1728 Assemble all undocumented Z80 instructions without warning.
1729 @item -warn-undocumented-instructions
1731 Issue a warning for undocumented Z80 instructions that also work on R800.
1732 @item -warn-unportable-instructions
1734 Issue a warning for undocumented Z80 instructions that do not work on R800.
1735 @item -forbid-undocumented-instructions
1737 Treat all undocumented instructions as errors.
1738 @item -forbid-unportable-instructions
1740 Treat undocumented Z80 instructions that do not work on R800 as errors.
1747 * Manual:: Structure of this Manual
1748 * GNU Assembler:: The GNU Assembler
1749 * Object Formats:: Object File Formats
1750 * Command Line:: Command Line
1751 * Input Files:: Input Files
1752 * Object:: Output (Object) File
1753 * Errors:: Error and Warning Messages
1757 @section Structure of this Manual
1759 @cindex manual, structure and purpose
1760 This manual is intended to describe what you need to know to use
1761 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1762 notation for symbols, constants, and expressions; the directives that
1763 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1766 We also cover special features in the @value{TARGET}
1767 configuration of @command{@value{AS}}, including assembler directives.
1770 This manual also describes some of the machine-dependent features of
1771 various flavors of the assembler.
1774 @cindex machine instructions (not covered)
1775 On the other hand, this manual is @emph{not} intended as an introduction
1776 to programming in assembly language---let alone programming in general!
1777 In a similar vein, we make no attempt to introduce the machine
1778 architecture; we do @emph{not} describe the instruction set, standard
1779 mnemonics, registers or addressing modes that are standard to a
1780 particular architecture.
1782 You may want to consult the manufacturer's
1783 machine architecture manual for this information.
1787 For information on the H8/300 machine instruction set, see @cite{H8/300
1788 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1789 Programming Manual} (Renesas).
1792 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1793 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1794 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1795 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1798 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1802 @c I think this is premature---doc@cygnus.com, 17jan1991
1804 Throughout this manual, we assume that you are running @dfn{GNU},
1805 the portable operating system from the @dfn{Free Software
1806 Foundation, Inc.}. This restricts our attention to certain kinds of
1807 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1808 once this assumption is granted examples and definitions need less
1811 @command{@value{AS}} is part of a team of programs that turn a high-level
1812 human-readable series of instructions into a low-level
1813 computer-readable series of instructions. Different versions of
1814 @command{@value{AS}} are used for different kinds of computer.
1817 @c There used to be a section "Terminology" here, which defined
1818 @c "contents", "byte", "word", and "long". Defining "word" to any
1819 @c particular size is confusing when the .word directive may generate 16
1820 @c bits on one machine and 32 bits on another; in general, for the user
1821 @c version of this manual, none of these terms seem essential to define.
1822 @c They were used very little even in the former draft of the manual;
1823 @c this draft makes an effort to avoid them (except in names of
1827 @section The GNU Assembler
1829 @c man begin DESCRIPTION
1831 @sc{gnu} @command{as} is really a family of assemblers.
1833 This manual describes @command{@value{AS}}, a member of that family which is
1834 configured for the @value{TARGET} architectures.
1836 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1837 should find a fairly similar environment when you use it on another
1838 architecture. Each version has much in common with the others,
1839 including object file formats, most assembler directives (often called
1840 @dfn{pseudo-ops}) and assembler syntax.@refill
1842 @cindex purpose of @sc{gnu} assembler
1843 @command{@value{AS}} is primarily intended to assemble the output of the
1844 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1845 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1846 assemble correctly everything that other assemblers for the same
1847 machine would assemble.
1849 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1852 @c This remark should appear in generic version of manual; assumption
1853 @c here is that generic version sets M680x0.
1854 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1855 assembler for the same architecture; for example, we know of several
1856 incompatible versions of 680x0 assembly language syntax.
1861 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1862 program in one pass of the source file. This has a subtle impact on the
1863 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1865 @node Object Formats
1866 @section Object File Formats
1868 @cindex object file format
1869 The @sc{gnu} assembler can be configured to produce several alternative
1870 object file formats. For the most part, this does not affect how you
1871 write assembly language programs; but directives for debugging symbols
1872 are typically different in different file formats. @xref{Symbol
1873 Attributes,,Symbol Attributes}.
1876 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1877 @value{OBJ-NAME} format object files.
1879 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1881 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1882 @code{b.out} or COFF format object files.
1885 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1886 SOM or ELF format object files.
1891 @section Command Line
1893 @cindex command line conventions
1895 After the program name @command{@value{AS}}, the command line may contain
1896 options and file names. Options may appear in any order, and may be
1897 before, after, or between file names. The order of file names is
1900 @cindex standard input, as input file
1902 @file{--} (two hyphens) by itself names the standard input file
1903 explicitly, as one of the files for @command{@value{AS}} to assemble.
1905 @cindex options, command line
1906 Except for @samp{--} any command line argument that begins with a
1907 hyphen (@samp{-}) is an option. Each option changes the behavior of
1908 @command{@value{AS}}. No option changes the way another option works. An
1909 option is a @samp{-} followed by one or more letters; the case of
1910 the letter is important. All options are optional.
1912 Some options expect exactly one file name to follow them. The file
1913 name may either immediately follow the option's letter (compatible
1914 with older assemblers) or it may be the next command argument (@sc{gnu}
1915 standard). These two command lines are equivalent:
1918 @value{AS} -o my-object-file.o mumble.s
1919 @value{AS} -omy-object-file.o mumble.s
1923 @section Input Files
1926 @cindex source program
1927 @cindex files, input
1928 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1929 describe the program input to one run of @command{@value{AS}}. The program may
1930 be in one or more files; how the source is partitioned into files
1931 doesn't change the meaning of the source.
1933 @c I added "con" prefix to "catenation" just to prove I can overcome my
1934 @c APL training... doc@cygnus.com
1935 The source program is a concatenation of the text in all the files, in the
1938 @c man begin DESCRIPTION
1939 Each time you run @command{@value{AS}} it assembles exactly one source
1940 program. The source program is made up of one or more files.
1941 (The standard input is also a file.)
1943 You give @command{@value{AS}} a command line that has zero or more input file
1944 names. The input files are read (from left file name to right). A
1945 command line argument (in any position) that has no special meaning
1946 is taken to be an input file name.
1948 If you give @command{@value{AS}} no file names it attempts to read one input file
1949 from the @command{@value{AS}} standard input, which is normally your terminal. You
1950 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1953 Use @samp{--} if you need to explicitly name the standard input file
1954 in your command line.
1956 If the source is empty, @command{@value{AS}} produces a small, empty object
1961 @subheading Filenames and Line-numbers
1963 @cindex input file linenumbers
1964 @cindex line numbers, in input files
1965 There are two ways of locating a line in the input file (or files) and
1966 either may be used in reporting error messages. One way refers to a line
1967 number in a physical file; the other refers to a line number in a
1968 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1970 @dfn{Physical files} are those files named in the command line given
1971 to @command{@value{AS}}.
1973 @dfn{Logical files} are simply names declared explicitly by assembler
1974 directives; they bear no relation to physical files. Logical file names help
1975 error messages reflect the original source file, when @command{@value{AS}} source
1976 is itself synthesized from other files. @command{@value{AS}} understands the
1977 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1978 @ref{File,,@code{.file}}.
1981 @section Output (Object) File
1987 Every time you run @command{@value{AS}} it produces an output file, which is
1988 your assembly language program translated into numbers. This file
1989 is the object file. Its default name is
1997 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1999 You can give it another name by using the @option{-o} option. Conventionally,
2000 object file names end with @file{.o}. The default name is used for historical
2001 reasons: older assemblers were capable of assembling self-contained programs
2002 directly into a runnable program. (For some formats, this isn't currently
2003 possible, but it can be done for the @code{a.out} format.)
2007 The object file is meant for input to the linker @code{@value{LD}}. It contains
2008 assembled program code, information to help @code{@value{LD}} integrate
2009 the assembled program into a runnable file, and (optionally) symbolic
2010 information for the debugger.
2012 @c link above to some info file(s) like the description of a.out.
2013 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
2016 @section Error and Warning Messages
2018 @c man begin DESCRIPTION
2020 @cindex error messages
2021 @cindex warning messages
2022 @cindex messages from assembler
2023 @command{@value{AS}} may write warnings and error messages to the standard error
2024 file (usually your terminal). This should not happen when a compiler
2025 runs @command{@value{AS}} automatically. Warnings report an assumption made so
2026 that @command{@value{AS}} could keep assembling a flawed program; errors report a
2027 grave problem that stops the assembly.
2031 @cindex format of warning messages
2032 Warning messages have the format
2035 file_name:@b{NNN}:Warning Message Text
2039 @cindex line numbers, in warnings/errors
2040 (where @b{NNN} is a line number). If a logical file name has been given
2041 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
2042 the current input file is used. If a logical line number was given
2044 (@pxref{Line,,@code{.line}})
2046 then it is used to calculate the number printed,
2047 otherwise the actual line in the current source file is printed. The
2048 message text is intended to be self explanatory (in the grand Unix
2051 @cindex format of error messages
2052 Error messages have the format
2054 file_name:@b{NNN}:FATAL:Error Message Text
2056 The file name and line number are derived as for warning
2057 messages. The actual message text may be rather less explanatory
2058 because many of them aren't supposed to happen.
2061 @chapter Command-Line Options
2063 @cindex options, all versions of assembler
2064 This chapter describes command-line options available in @emph{all}
2065 versions of the @sc{gnu} assembler; see @ref{Machine Dependencies},
2066 for options specific
2068 to the @value{TARGET} target.
2071 to particular machine architectures.
2074 @c man begin DESCRIPTION
2076 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
2077 you can use the @samp{-Wa} option to pass arguments through to the assembler.
2078 The assembler arguments must be separated from each other (and the @samp{-Wa})
2079 by commas. For example:
2082 gcc -c -g -O -Wa,-alh,-L file.c
2086 This passes two options to the assembler: @samp{-alh} (emit a listing to
2087 standard output with high-level and assembly source) and @samp{-L} (retain
2088 local symbols in the symbol table).
2090 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
2091 command-line options are automatically passed to the assembler by the compiler.
2092 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
2093 precisely what options it passes to each compilation pass, including the
2099 * a:: -a[cdghlns] enable listings
2100 * alternate:: --alternate enable alternate macro syntax
2101 * D:: -D for compatibility
2102 * f:: -f to work faster
2103 * I:: -I for .include search path
2104 @ifclear DIFF-TBL-KLUGE
2105 * K:: -K for compatibility
2107 @ifset DIFF-TBL-KLUGE
2108 * K:: -K for difference tables
2111 * L:: -L to retain local symbols
2112 * listing:: --listing-XXX to configure listing output
2113 * M:: -M or --mri to assemble in MRI compatibility mode
2114 * MD:: --MD for dependency tracking
2115 * o:: -o to name the object file
2116 * R:: -R to join data and text sections
2117 * statistics:: --statistics to see statistics about assembly
2118 * traditional-format:: --traditional-format for compatible output
2119 * v:: -v to announce version
2120 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
2121 * Z:: -Z to make object file even after errors
2125 @section Enable Listings: @option{-a[cdghlns]}
2135 @cindex listings, enabling
2136 @cindex assembly listings, enabling
2138 These options enable listing output from the assembler. By itself,
2139 @samp{-a} requests high-level, assembly, and symbols listing.
2140 You can use other letters to select specific options for the list:
2141 @samp{-ah} requests a high-level language listing,
2142 @samp{-al} requests an output-program assembly listing, and
2143 @samp{-as} requests a symbol table listing.
2144 High-level listings require that a compiler debugging option like
2145 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
2148 Use the @samp{-ag} option to print a first section with general assembly
2149 information, like @value{AS} version, switches passed, or time stamp.
2151 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
2152 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
2153 other conditional), or a true @code{.if} followed by an @code{.else}, will be
2154 omitted from the listing.
2156 Use the @samp{-ad} option to omit debugging directives from the
2159 Once you have specified one of these options, you can further control
2160 listing output and its appearance using the directives @code{.list},
2161 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
2163 The @samp{-an} option turns off all forms processing.
2164 If you do not request listing output with one of the @samp{-a} options, the
2165 listing-control directives have no effect.
2167 The letters after @samp{-a} may be combined into one option,
2168 @emph{e.g.}, @samp{-aln}.
2170 Note if the assembler source is coming from the standard input (e.g.,
2172 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
2173 is being used) then the listing will not contain any comments or preprocessor
2174 directives. This is because the listing code buffers input source lines from
2175 stdin only after they have been preprocessed by the assembler. This reduces
2176 memory usage and makes the code more efficient.
2179 @section @option{--alternate}
2182 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
2185 @section @option{-D}
2188 This option has no effect whatsoever, but it is accepted to make it more
2189 likely that scripts written for other assemblers also work with
2190 @command{@value{AS}}.
2193 @section Work Faster: @option{-f}
2196 @cindex trusted compiler
2197 @cindex faster processing (@option{-f})
2198 @samp{-f} should only be used when assembling programs written by a
2199 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
2200 and comment preprocessing on
2201 the input file(s) before assembling them. @xref{Preprocessing,
2205 @emph{Warning:} if you use @samp{-f} when the files actually need to be
2206 preprocessed (if they contain comments, for example), @command{@value{AS}} does
2211 @section @code{.include} Search Path: @option{-I} @var{path}
2213 @kindex -I @var{path}
2214 @cindex paths for @code{.include}
2215 @cindex search path for @code{.include}
2216 @cindex @code{include} directive search path
2217 Use this option to add a @var{path} to the list of directories
2218 @command{@value{AS}} searches for files specified in @code{.include}
2219 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
2220 many times as necessary to include a variety of paths. The current
2221 working directory is always searched first; after that, @command{@value{AS}}
2222 searches any @samp{-I} directories in the same order as they were
2223 specified (left to right) on the command line.
2226 @section Difference Tables: @option{-K}
2229 @ifclear DIFF-TBL-KLUGE
2230 On the @value{TARGET} family, this option is allowed, but has no effect. It is
2231 permitted for compatibility with the @sc{gnu} assembler on other platforms,
2232 where it can be used to warn when the assembler alters the machine code
2233 generated for @samp{.word} directives in difference tables. The @value{TARGET}
2234 family does not have the addressing limitations that sometimes lead to this
2235 alteration on other platforms.
2238 @ifset DIFF-TBL-KLUGE
2239 @cindex difference tables, warning
2240 @cindex warning for altered difference tables
2241 @command{@value{AS}} sometimes alters the code emitted for directives of the
2242 form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}.
2243 You can use the @samp{-K} option if you want a warning issued when this
2248 @section Include Local Symbols: @option{-L}
2251 @cindex local symbols, retaining in output
2252 Symbols beginning with system-specific local label prefixes, typically
2253 @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are
2254 called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see
2255 such symbols when debugging, because they are intended for the use of
2256 programs (like compilers) that compose assembler programs, not for your
2257 notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard
2258 such symbols, so you do not normally debug with them.
2260 This option tells @command{@value{AS}} to retain those local symbols
2261 in the object file. Usually if you do this you also tell the linker
2262 @code{@value{LD}} to preserve those symbols.
2265 @section Configuring listing output: @option{--listing}
2267 The listing feature of the assembler can be enabled via the command line switch
2268 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
2269 hex dump of the corresponding locations in the output object file, and displays
2270 them as a listing file. The format of this listing can be controlled by
2271 directives inside the assembler source (i.e., @code{.list} (@pxref{List}),
2272 @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}),
2273 @code{.psize} (@pxref{Psize}), and
2274 @code{.eject} (@pxref{Eject}) and also by the following switches:
2277 @item --listing-lhs-width=@samp{number}
2278 @kindex --listing-lhs-width
2279 @cindex Width of first line disassembly output
2280 Sets the maximum width, in words, of the first line of the hex byte dump. This
2281 dump appears on the left hand side of the listing output.
2283 @item --listing-lhs-width2=@samp{number}
2284 @kindex --listing-lhs-width2
2285 @cindex Width of continuation lines of disassembly output
2286 Sets the maximum width, in words, of any further lines of the hex byte dump for
2287 a given input source line. If this value is not specified, it defaults to being
2288 the same as the value specified for @samp{--listing-lhs-width}. If neither
2289 switch is used the default is to one.
2291 @item --listing-rhs-width=@samp{number}
2292 @kindex --listing-rhs-width
2293 @cindex Width of source line output
2294 Sets the maximum width, in characters, of the source line that is displayed
2295 alongside the hex dump. The default value for this parameter is 100. The
2296 source line is displayed on the right hand side of the listing output.
2298 @item --listing-cont-lines=@samp{number}
2299 @kindex --listing-cont-lines
2300 @cindex Maximum number of continuation lines
2301 Sets the maximum number of continuation lines of hex dump that will be
2302 displayed for a given single line of source input. The default value is 4.
2306 @section Assemble in MRI Compatibility Mode: @option{-M}
2309 @cindex MRI compatibility mode
2310 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
2311 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
2312 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
2313 configured target) assembler from Microtec Research. The exact nature of the
2314 MRI syntax will not be documented here; see the MRI manuals for more
2315 information. Note in particular that the handling of macros and macro
2316 arguments is somewhat different. The purpose of this option is to permit
2317 assembling existing MRI assembler code using @command{@value{AS}}.
2319 The MRI compatibility is not complete. Certain operations of the MRI assembler
2320 depend upon its object file format, and can not be supported using other object
2321 file formats. Supporting these would require enhancing each object file format
2322 individually. These are:
2325 @item global symbols in common section
2327 The m68k MRI assembler supports common sections which are merged by the linker.
2328 Other object file formats do not support this. @command{@value{AS}} handles
2329 common sections by treating them as a single common symbol. It permits local
2330 symbols to be defined within a common section, but it can not support global
2331 symbols, since it has no way to describe them.
2333 @item complex relocations
2335 The MRI assemblers support relocations against a negated section address, and
2336 relocations which combine the start addresses of two or more sections. These
2337 are not support by other object file formats.
2339 @item @code{END} pseudo-op specifying start address
2341 The MRI @code{END} pseudo-op permits the specification of a start address.
2342 This is not supported by other object file formats. The start address may
2343 instead be specified using the @option{-e} option to the linker, or in a linker
2346 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
2348 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
2349 name to the output file. This is not supported by other object file formats.
2351 @item @code{ORG} pseudo-op
2353 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
2354 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
2355 which changes the location within the current section. Absolute sections are
2356 not supported by other object file formats. The address of a section may be
2357 assigned within a linker script.
2360 There are some other features of the MRI assembler which are not supported by
2361 @command{@value{AS}}, typically either because they are difficult or because they
2362 seem of little consequence. Some of these may be supported in future releases.
2366 @item EBCDIC strings
2368 EBCDIC strings are not supported.
2370 @item packed binary coded decimal
2372 Packed binary coded decimal is not supported. This means that the @code{DC.P}
2373 and @code{DCB.P} pseudo-ops are not supported.
2375 @item @code{FEQU} pseudo-op
2377 The m68k @code{FEQU} pseudo-op is not supported.
2379 @item @code{NOOBJ} pseudo-op
2381 The m68k @code{NOOBJ} pseudo-op is not supported.
2383 @item @code{OPT} branch control options
2385 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
2386 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
2387 relaxes all branches, whether forward or backward, to an appropriate size, so
2388 these options serve no purpose.
2390 @item @code{OPT} list control options
2392 The following m68k @code{OPT} list control options are ignored: @code{C},
2393 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
2394 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
2396 @item other @code{OPT} options
2398 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
2399 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
2401 @item @code{OPT} @code{D} option is default
2403 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
2404 @code{OPT NOD} may be used to turn it off.
2406 @item @code{XREF} pseudo-op.
2408 The m68k @code{XREF} pseudo-op is ignored.
2410 @item @code{.debug} pseudo-op
2412 The i960 @code{.debug} pseudo-op is not supported.
2414 @item @code{.extended} pseudo-op
2416 The i960 @code{.extended} pseudo-op is not supported.
2418 @item @code{.list} pseudo-op.
2420 The various options of the i960 @code{.list} pseudo-op are not supported.
2422 @item @code{.optimize} pseudo-op
2424 The i960 @code{.optimize} pseudo-op is not supported.
2426 @item @code{.output} pseudo-op
2428 The i960 @code{.output} pseudo-op is not supported.
2430 @item @code{.setreal} pseudo-op
2432 The i960 @code{.setreal} pseudo-op is not supported.
2437 @section Dependency Tracking: @option{--MD}
2440 @cindex dependency tracking
2443 @command{@value{AS}} can generate a dependency file for the file it creates. This
2444 file consists of a single rule suitable for @code{make} describing the
2445 dependencies of the main source file.
2447 The rule is written to the file named in its argument.
2449 This feature is used in the automatic updating of makefiles.
2452 @section Name the Object File: @option{-o}
2455 @cindex naming object file
2456 @cindex object file name
2457 There is always one object file output when you run @command{@value{AS}}. By
2458 default it has the name
2461 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
2475 You use this option (which takes exactly one filename) to give the
2476 object file a different name.
2478 Whatever the object file is called, @command{@value{AS}} overwrites any
2479 existing file of the same name.
2482 @section Join Data and Text Sections: @option{-R}
2485 @cindex data and text sections, joining
2486 @cindex text and data sections, joining
2487 @cindex joining text and data sections
2488 @cindex merging text and data sections
2489 @option{-R} tells @command{@value{AS}} to write the object file as if all
2490 data-section data lives in the text section. This is only done at
2491 the very last moment: your binary data are the same, but data
2492 section parts are relocated differently. The data section part of
2493 your object file is zero bytes long because all its bytes are
2494 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
2496 When you specify @option{-R} it would be possible to generate shorter
2497 address displacements (because we do not have to cross between text and
2498 data section). We refrain from doing this simply for compatibility with
2499 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
2502 When @command{@value{AS}} is configured for COFF or ELF output,
2503 this option is only useful if you use sections named @samp{.text} and
2508 @option{-R} is not supported for any of the HPPA targets. Using
2509 @option{-R} generates a warning from @command{@value{AS}}.
2513 @section Display Assembly Statistics: @option{--statistics}
2515 @kindex --statistics
2516 @cindex statistics, about assembly
2517 @cindex time, total for assembly
2518 @cindex space used, maximum for assembly
2519 Use @samp{--statistics} to display two statistics about the resources used by
2520 @command{@value{AS}}: the maximum amount of space allocated during the assembly
2521 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
2524 @node traditional-format
2525 @section Compatible Output: @option{--traditional-format}
2527 @kindex --traditional-format
2528 For some targets, the output of @command{@value{AS}} is different in some ways
2529 from the output of some existing assembler. This switch requests
2530 @command{@value{AS}} to use the traditional format instead.
2532 For example, it disables the exception frame optimizations which
2533 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
2536 @section Announce Version: @option{-v}
2540 @cindex assembler version
2541 @cindex version of assembler
2542 You can find out what version of as is running by including the
2543 option @samp{-v} (which you can also spell as @samp{-version}) on the
2547 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
2549 @command{@value{AS}} should never give a warning or error message when
2550 assembling compiler output. But programs written by people often
2551 cause @command{@value{AS}} to give a warning that a particular assumption was
2552 made. All such warnings are directed to the standard error file.
2556 @cindex suppressing warnings
2557 @cindex warnings, suppressing
2558 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
2559 This only affects the warning messages: it does not change any particular of
2560 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
2563 @kindex --fatal-warnings
2564 @cindex errors, caused by warnings
2565 @cindex warnings, causing error
2566 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
2567 files that generate warnings to be in error.
2570 @cindex warnings, switching on
2571 You can switch these options off again by specifying @option{--warn}, which
2572 causes warnings to be output as usual.
2575 @section Generate Object File in Spite of Errors: @option{-Z}
2576 @cindex object file, after errors
2577 @cindex errors, continuing after
2578 After an error message, @command{@value{AS}} normally produces no output. If for
2579 some reason you are interested in object file output even after
2580 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
2581 option. If there are any errors, @command{@value{AS}} continues anyways, and
2582 writes an object file after a final warning message of the form @samp{@var{n}
2583 errors, @var{m} warnings, generating bad object file.}
2588 @cindex machine-independent syntax
2589 @cindex syntax, machine-independent
2590 This chapter describes the machine-independent syntax allowed in a
2591 source file. @command{@value{AS}} syntax is similar to what many other
2592 assemblers use; it is inspired by the BSD 4.2
2597 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
2601 * Preprocessing:: Preprocessing
2602 * Whitespace:: Whitespace
2603 * Comments:: Comments
2604 * Symbol Intro:: Symbols
2605 * Statements:: Statements
2606 * Constants:: Constants
2610 @section Preprocessing
2612 @cindex preprocessing
2613 The @command{@value{AS}} internal preprocessor:
2615 @cindex whitespace, removed by preprocessor
2617 adjusts and removes extra whitespace. It leaves one space or tab before
2618 the keywords on a line, and turns any other whitespace on the line into
2621 @cindex comments, removed by preprocessor
2623 removes all comments, replacing them with a single space, or an
2624 appropriate number of newlines.
2626 @cindex constants, converted by preprocessor
2628 converts character constants into the appropriate numeric values.
2631 It does not do macro processing, include file handling, or
2632 anything else you may get from your C compiler's preprocessor. You can
2633 do include file processing with the @code{.include} directive
2634 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2635 to get other ``CPP'' style preprocessing by giving the input file a
2636 @samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of
2637 Output, gcc.info, Using GNU CC}.
2639 Excess whitespace, comments, and character constants
2640 cannot be used in the portions of the input text that are not
2643 @cindex turning preprocessing on and off
2644 @cindex preprocessing, turning on and off
2647 If the first line of an input file is @code{#NO_APP} or if you use the
2648 @samp{-f} option, whitespace and comments are not removed from the input file.
2649 Within an input file, you can ask for whitespace and comment removal in
2650 specific portions of the by putting a line that says @code{#APP} before the
2651 text that may contain whitespace or comments, and putting a line that says
2652 @code{#NO_APP} after this text. This feature is mainly intend to support
2653 @code{asm} statements in compilers whose output is otherwise free of comments
2660 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2661 Whitespace is used to separate symbols, and to make programs neater for
2662 people to read. Unless within character constants
2663 (@pxref{Characters,,Character Constants}), any whitespace means the same
2664 as exactly one space.
2670 There are two ways of rendering comments to @command{@value{AS}}. In both
2671 cases the comment is equivalent to one space.
2673 Anything from @samp{/*} through the next @samp{*/} is a comment.
2674 This means you may not nest these comments.
2678 The only way to include a newline ('\n') in a comment
2679 is to use this sort of comment.
2682 /* This sort of comment does not nest. */
2685 @cindex line comment character
2686 Anything from a @dfn{line comment} character up to the next newline is
2687 considered a comment and is ignored. The line comment character is target
2688 specific, and some targets multiple comment characters. Some targets also have
2689 line comment characters that only work if they are the first character on a
2690 line. Some targets use a sequence of two characters to introduce a line
2691 comment. Some targets can also change their line comment characters depending
2692 upon command line options that have been used. For more details see the
2693 @emph{Syntax} section in the documentation for individual targets.
2695 If the line comment character is the hash sign (@samp{#}) then it still has the
2696 special ability to enable and disable preprocessing (@pxref{Preprocessing}) and
2697 to specify logical line numbers:
2700 @cindex lines starting with @code{#}
2701 @cindex logical line numbers
2702 To be compatible with past assemblers, lines that begin with @samp{#} have a
2703 special interpretation. Following the @samp{#} should be an absolute
2704 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2705 line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a
2706 new logical file name. The rest of the line, if any, should be whitespace.
2708 If the first non-whitespace characters on the line are not numeric,
2709 the line is ignored. (Just like a comment.)
2712 # This is an ordinary comment.
2713 # 42-6 "new_file_name" # New logical file name
2714 # This is logical line # 36.
2716 This feature is deprecated, and may disappear from future versions
2717 of @command{@value{AS}}.
2722 @cindex characters used in symbols
2723 @ifclear SPECIAL-SYMS
2724 A @dfn{symbol} is one or more characters chosen from the set of all
2725 letters (both upper and lower case), digits and the three characters
2731 A @dfn{symbol} is one or more characters chosen from the set of all
2732 letters (both upper and lower case), digits and the three characters
2733 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2739 On most machines, you can also use @code{$} in symbol names; exceptions
2740 are noted in @ref{Machine Dependencies}.
2742 No symbol may begin with a digit. Case is significant.
2743 There is no length limit: all characters are significant. Multibyte characters
2744 are supported. Symbols are delimited by characters not in that set, or by the
2745 beginning of a file (since the source program must end with a newline, the end
2746 of a file is not a possible symbol delimiter). @xref{Symbols}.
2747 @cindex length of symbols
2752 @cindex statements, structure of
2753 @cindex line separator character
2754 @cindex statement separator character
2756 A @dfn{statement} ends at a newline character (@samp{\n}) or a
2757 @dfn{line separator character}. The line separator character is target
2758 specific and described in the @emph{Syntax} section of each
2759 target's documentation. Not all targets support a line separator character.
2760 The newline or line separator character is considered to be part of the
2761 preceding statement. Newlines and separators within character constants are an
2762 exception: they do not end statements.
2764 @cindex newline, required at file end
2765 @cindex EOF, newline must precede
2766 It is an error to end any statement with end-of-file: the last
2767 character of any input file should be a newline.@refill
2769 An empty statement is allowed, and may include whitespace. It is ignored.
2771 @cindex instructions and directives
2772 @cindex directives and instructions
2773 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2774 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2776 A statement begins with zero or more labels, optionally followed by a
2777 key symbol which determines what kind of statement it is. The key
2778 symbol determines the syntax of the rest of the statement. If the
2779 symbol begins with a dot @samp{.} then the statement is an assembler
2780 directive: typically valid for any computer. If the symbol begins with
2781 a letter the statement is an assembly language @dfn{instruction}: it
2782 assembles into a machine language instruction.
2784 Different versions of @command{@value{AS}} for different computers
2785 recognize different instructions. In fact, the same symbol may
2786 represent a different instruction in a different computer's assembly
2790 @cindex @code{:} (label)
2791 @cindex label (@code{:})
2792 A label is a symbol immediately followed by a colon (@code{:}).
2793 Whitespace before a label or after a colon is permitted, but you may not
2794 have whitespace between a label's symbol and its colon. @xref{Labels}.
2797 For HPPA targets, labels need not be immediately followed by a colon, but
2798 the definition of a label must begin in column zero. This also implies that
2799 only one label may be defined on each line.
2803 label: .directive followed by something
2804 another_label: # This is an empty statement.
2805 instruction operand_1, operand_2, @dots{}
2812 A constant is a number, written so that its value is known by
2813 inspection, without knowing any context. Like this:
2816 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2817 .ascii "Ring the bell\7" # A string constant.
2818 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2819 .float 0f-314159265358979323846264338327\
2820 95028841971.693993751E-40 # - pi, a flonum.
2825 * Characters:: Character Constants
2826 * Numbers:: Number Constants
2830 @subsection Character Constants
2832 @cindex character constants
2833 @cindex constants, character
2834 There are two kinds of character constants. A @dfn{character} stands
2835 for one character in one byte and its value may be used in
2836 numeric expressions. String constants (properly called string
2837 @emph{literals}) are potentially many bytes and their values may not be
2838 used in arithmetic expressions.
2842 * Chars:: Characters
2846 @subsubsection Strings
2848 @cindex string constants
2849 @cindex constants, string
2850 A @dfn{string} is written between double-quotes. It may contain
2851 double-quotes or null characters. The way to get special characters
2852 into a string is to @dfn{escape} these characters: precede them with
2853 a backslash @samp{\} character. For example @samp{\\} represents
2854 one backslash: the first @code{\} is an escape which tells
2855 @command{@value{AS}} to interpret the second character literally as a backslash
2856 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2857 escape character). The complete list of escapes follows.
2859 @cindex escape codes, character
2860 @cindex character escape codes
2863 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2865 @cindex @code{\b} (backspace character)
2866 @cindex backspace (@code{\b})
2868 Mnemonic for backspace; for ASCII this is octal code 010.
2871 @c Mnemonic for EOText; for ASCII this is octal code 004.
2873 @cindex @code{\f} (formfeed character)
2874 @cindex formfeed (@code{\f})
2876 Mnemonic for FormFeed; for ASCII this is octal code 014.
2878 @cindex @code{\n} (newline character)
2879 @cindex newline (@code{\n})
2881 Mnemonic for newline; for ASCII this is octal code 012.
2884 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2886 @cindex @code{\r} (carriage return character)
2887 @cindex carriage return (@code{\r})
2889 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2892 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2893 @c other assemblers.
2895 @cindex @code{\t} (tab)
2896 @cindex tab (@code{\t})
2898 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2901 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2902 @c @item \x @var{digit} @var{digit} @var{digit}
2903 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2905 @cindex @code{\@var{ddd}} (octal character code)
2906 @cindex octal character code (@code{\@var{ddd}})
2907 @item \ @var{digit} @var{digit} @var{digit}
2908 An octal character code. The numeric code is 3 octal digits.
2909 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2910 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2912 @cindex @code{\@var{xd...}} (hex character code)
2913 @cindex hex character code (@code{\@var{xd...}})
2914 @item \@code{x} @var{hex-digits...}
2915 A hex character code. All trailing hex digits are combined. Either upper or
2916 lower case @code{x} works.
2918 @cindex @code{\\} (@samp{\} character)
2919 @cindex backslash (@code{\\})
2921 Represents one @samp{\} character.
2924 @c Represents one @samp{'} (accent acute) character.
2925 @c This is needed in single character literals
2926 @c (@xref{Characters,,Character Constants}.) to represent
2929 @cindex @code{\"} (doublequote character)
2930 @cindex doublequote (@code{\"})
2932 Represents one @samp{"} character. Needed in strings to represent
2933 this character, because an unescaped @samp{"} would end the string.
2935 @item \ @var{anything-else}
2936 Any other character when escaped by @kbd{\} gives a warning, but
2937 assembles as if the @samp{\} was not present. The idea is that if
2938 you used an escape sequence you clearly didn't want the literal
2939 interpretation of the following character. However @command{@value{AS}} has no
2940 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2941 code and warns you of the fact.
2944 Which characters are escapable, and what those escapes represent,
2945 varies widely among assemblers. The current set is what we think
2946 the BSD 4.2 assembler recognizes, and is a subset of what most C
2947 compilers recognize. If you are in doubt, do not use an escape
2951 @subsubsection Characters
2953 @cindex single character constant
2954 @cindex character, single
2955 @cindex constant, single character
2956 A single character may be written as a single quote immediately
2957 followed by that character. The same escapes apply to characters as
2958 to strings. So if you want to write the character backslash, you
2959 must write @kbd{'\\} where the first @code{\} escapes the second
2960 @code{\}. As you can see, the quote is an acute accent, not a
2961 grave accent. A newline
2963 @ifclear abnormal-separator
2964 (or semicolon @samp{;})
2966 @ifset abnormal-separator
2968 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2973 immediately following an acute accent is taken as a literal character
2974 and does not count as the end of a statement. The value of a character
2975 constant in a numeric expression is the machine's byte-wide code for
2976 that character. @command{@value{AS}} assumes your character code is ASCII:
2977 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2980 @subsection Number Constants
2982 @cindex constants, number
2983 @cindex number constants
2984 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2985 are stored in the target machine. @emph{Integers} are numbers that
2986 would fit into an @code{int} in the C language. @emph{Bignums} are
2987 integers, but they are stored in more than 32 bits. @emph{Flonums}
2988 are floating point numbers, described below.
2991 * Integers:: Integers
2996 * Bit Fields:: Bit Fields
3002 @subsubsection Integers
3004 @cindex constants, integer
3006 @cindex binary integers
3007 @cindex integers, binary
3008 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
3009 the binary digits @samp{01}.
3011 @cindex octal integers
3012 @cindex integers, octal
3013 An octal integer is @samp{0} followed by zero or more of the octal
3014 digits (@samp{01234567}).
3016 @cindex decimal integers
3017 @cindex integers, decimal
3018 A decimal integer starts with a non-zero digit followed by zero or
3019 more digits (@samp{0123456789}).
3021 @cindex hexadecimal integers
3022 @cindex integers, hexadecimal
3023 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
3024 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
3026 Integers have the usual values. To denote a negative integer, use
3027 the prefix operator @samp{-} discussed under expressions
3028 (@pxref{Prefix Ops,,Prefix Operators}).
3031 @subsubsection Bignums
3034 @cindex constants, bignum
3035 A @dfn{bignum} has the same syntax and semantics as an integer
3036 except that the number (or its negative) takes more than 32 bits to
3037 represent in binary. The distinction is made because in some places
3038 integers are permitted while bignums are not.
3041 @subsubsection Flonums
3043 @cindex floating point numbers
3044 @cindex constants, floating point
3046 @cindex precision, floating point
3047 A @dfn{flonum} represents a floating point number. The translation is
3048 indirect: a decimal floating point number from the text is converted by
3049 @command{@value{AS}} to a generic binary floating point number of more than
3050 sufficient precision. This generic floating point number is converted
3051 to a particular computer's floating point format (or formats) by a
3052 portion of @command{@value{AS}} specialized to that computer.
3054 A flonum is written by writing (in order)
3059 (@samp{0} is optional on the HPPA.)
3063 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
3065 @kbd{e} is recommended. Case is not important.
3067 @c FIXME: verify if flonum syntax really this vague for most cases
3068 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
3069 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
3072 On the H8/300, Renesas / SuperH SH,
3073 and AMD 29K architectures, the letter must be
3074 one of the letters @samp{DFPRSX} (in upper or lower case).
3076 On the ARC, the letter must be one of the letters @samp{DFRS}
3077 (in upper or lower case).
3079 On the Intel 960 architecture, the letter must be
3080 one of the letters @samp{DFT} (in upper or lower case).
3082 On the HPPA architecture, the letter must be @samp{E} (upper case only).
3086 One of the letters @samp{DFRS} (in upper or lower case).
3089 One of the letters @samp{DFPRSX} (in upper or lower case).
3092 The letter @samp{E} (upper case only).
3095 One of the letters @samp{DFT} (in upper or lower case).
3100 An optional sign: either @samp{+} or @samp{-}.
3103 An optional @dfn{integer part}: zero or more decimal digits.
3106 An optional @dfn{fractional part}: @samp{.} followed by zero
3107 or more decimal digits.
3110 An optional exponent, consisting of:
3114 An @samp{E} or @samp{e}.
3115 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
3116 @c principle this can perfectly well be different on different targets.
3118 Optional sign: either @samp{+} or @samp{-}.
3120 One or more decimal digits.
3125 At least one of the integer part or the fractional part must be
3126 present. The floating point number has the usual base-10 value.
3128 @command{@value{AS}} does all processing using integers. Flonums are computed
3129 independently of any floating point hardware in the computer running
3130 @command{@value{AS}}.
3134 @c Bit fields are written as a general facility but are also controlled
3135 @c by a conditional-compilation flag---which is as of now (21mar91)
3136 @c turned on only by the i960 config of GAS.
3138 @subsubsection Bit Fields
3141 @cindex constants, bit field
3142 You can also define numeric constants as @dfn{bit fields}.
3143 Specify two numbers separated by a colon---
3145 @var{mask}:@var{value}
3148 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
3151 The resulting number is then packed
3153 @c this conditional paren in case bit fields turned on elsewhere than 960
3154 (in host-dependent byte order)
3156 into a field whose width depends on which assembler directive has the
3157 bit-field as its argument. Overflow (a result from the bitwise and
3158 requiring more binary digits to represent) is not an error; instead,
3159 more constants are generated, of the specified width, beginning with the
3160 least significant digits.@refill
3162 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
3163 @code{.short}, and @code{.word} accept bit-field arguments.
3168 @chapter Sections and Relocation
3173 * Secs Background:: Background
3174 * Ld Sections:: Linker Sections
3175 * As Sections:: Assembler Internal Sections
3176 * Sub-Sections:: Sub-Sections
3180 @node Secs Background
3183 Roughly, a section is a range of addresses, with no gaps; all data
3184 ``in'' those addresses is treated the same for some particular purpose.
3185 For example there may be a ``read only'' section.
3187 @cindex linker, and assembler
3188 @cindex assembler, and linker
3189 The linker @code{@value{LD}} reads many object files (partial programs) and
3190 combines their contents to form a runnable program. When @command{@value{AS}}
3191 emits an object file, the partial program is assumed to start at address 0.
3192 @code{@value{LD}} assigns the final addresses for the partial program, so that
3193 different partial programs do not overlap. This is actually an
3194 oversimplification, but it suffices to explain how @command{@value{AS}} uses
3197 @code{@value{LD}} moves blocks of bytes of your program to their run-time
3198 addresses. These blocks slide to their run-time addresses as rigid
3199 units; their length does not change and neither does the order of bytes
3200 within them. Such a rigid unit is called a @emph{section}. Assigning
3201 run-time addresses to sections is called @dfn{relocation}. It includes
3202 the task of adjusting mentions of object-file addresses so they refer to
3203 the proper run-time addresses.
3205 For the H8/300, and for the Renesas / SuperH SH,
3206 @command{@value{AS}} pads sections if needed to
3207 ensure they end on a word (sixteen bit) boundary.
3210 @cindex standard assembler sections
3211 An object file written by @command{@value{AS}} has at least three sections, any
3212 of which may be empty. These are named @dfn{text}, @dfn{data} and
3217 When it generates COFF or ELF output,
3219 @command{@value{AS}} can also generate whatever other named sections you specify
3220 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
3221 If you do not use any directives that place output in the @samp{.text}
3222 or @samp{.data} sections, these sections still exist, but are empty.
3227 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
3229 @command{@value{AS}} can also generate whatever other named sections you
3230 specify using the @samp{.space} and @samp{.subspace} directives. See
3231 @cite{HP9000 Series 800 Assembly Language Reference Manual}
3232 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
3233 assembler directives.
3236 Additionally, @command{@value{AS}} uses different names for the standard
3237 text, data, and bss sections when generating SOM output. Program text
3238 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
3239 BSS into @samp{$BSS$}.
3243 Within the object file, the text section starts at address @code{0}, the
3244 data section follows, and the bss section follows the data section.
3247 When generating either SOM or ELF output files on the HPPA, the text
3248 section starts at address @code{0}, the data section at address
3249 @code{0x4000000}, and the bss section follows the data section.
3252 To let @code{@value{LD}} know which data changes when the sections are
3253 relocated, and how to change that data, @command{@value{AS}} also writes to the
3254 object file details of the relocation needed. To perform relocation
3255 @code{@value{LD}} must know, each time an address in the object
3259 Where in the object file is the beginning of this reference to
3262 How long (in bytes) is this reference?
3264 Which section does the address refer to? What is the numeric value of
3266 (@var{address}) @minus{} (@var{start-address of section})?
3269 Is the reference to an address ``Program-Counter relative''?
3272 @cindex addresses, format of
3273 @cindex section-relative addressing
3274 In fact, every address @command{@value{AS}} ever uses is expressed as
3276 (@var{section}) + (@var{offset into section})
3279 Further, most expressions @command{@value{AS}} computes have this section-relative
3282 (For some object formats, such as SOM for the HPPA, some expressions are
3283 symbol-relative instead.)
3286 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
3287 @var{N} into section @var{secname}.''
3289 Apart from text, data and bss sections you need to know about the
3290 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
3291 addresses in the absolute section remain unchanged. For example, address
3292 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
3293 @code{@value{LD}}. Although the linker never arranges two partial programs'
3294 data sections with overlapping addresses after linking, @emph{by definition}
3295 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
3296 part of a program is always the same address when the program is running as
3297 address @code{@{absolute@ 239@}} in any other part of the program.
3299 The idea of sections is extended to the @dfn{undefined} section. Any
3300 address whose section is unknown at assembly time is by definition
3301 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
3302 Since numbers are always defined, the only way to generate an undefined
3303 address is to mention an undefined symbol. A reference to a named
3304 common block would be such a symbol: its value is unknown at assembly
3305 time so it has section @emph{undefined}.
3307 By analogy the word @emph{section} is used to describe groups of sections in
3308 the linked program. @code{@value{LD}} puts all partial programs' text
3309 sections in contiguous addresses in the linked program. It is
3310 customary to refer to the @emph{text section} of a program, meaning all
3311 the addresses of all partial programs' text sections. Likewise for
3312 data and bss sections.
3314 Some sections are manipulated by @code{@value{LD}}; others are invented for
3315 use of @command{@value{AS}} and have no meaning except during assembly.
3318 @section Linker Sections
3319 @code{@value{LD}} deals with just four kinds of sections, summarized below.
3324 @cindex named sections
3325 @cindex sections, named
3326 @item named sections
3329 @cindex text section
3330 @cindex data section
3334 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
3335 separate but equal sections. Anything you can say of one section is
3338 When the program is running, however, it is
3339 customary for the text section to be unalterable. The
3340 text section is often shared among processes: it contains
3341 instructions, constants and the like. The data section of a running
3342 program is usually alterable: for example, C variables would be stored
3343 in the data section.
3348 This section contains zeroed bytes when your program begins running. It
3349 is used to hold uninitialized variables or common storage. The length of
3350 each partial program's bss section is important, but because it starts
3351 out containing zeroed bytes there is no need to store explicit zero
3352 bytes in the object file. The bss section was invented to eliminate
3353 those explicit zeros from object files.
3355 @cindex absolute section
3356 @item absolute section
3357 Address 0 of this section is always ``relocated'' to runtime address 0.
3358 This is useful if you want to refer to an address that @code{@value{LD}} must
3359 not change when relocating. In this sense we speak of absolute
3360 addresses being ``unrelocatable'': they do not change during relocation.
3362 @cindex undefined section
3363 @item undefined section
3364 This ``section'' is a catch-all for address references to objects not in
3365 the preceding sections.
3366 @c FIXME: ref to some other doc on obj-file formats could go here.
3369 @cindex relocation example
3370 An idealized example of three relocatable sections follows.
3372 The example uses the traditional section names @samp{.text} and @samp{.data}.
3374 Memory addresses are on the horizontal axis.
3378 @c END TEXI2ROFF-KILL
3381 partial program # 1: |ttttt|dddd|00|
3388 partial program # 2: |TTT|DDD|000|
3391 +--+---+-----+--+----+---+-----+~~
3392 linked program: | |TTT|ttttt| |dddd|DDD|00000|
3393 +--+---+-----+--+----+---+-----+~~
3395 addresses: 0 @dots{}
3402 \line{\it Partial program \#1: \hfil}
3403 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3404 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
3406 \line{\it Partial program \#2: \hfil}
3407 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3408 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
3410 \line{\it linked program: \hfil}
3411 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
3412 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
3413 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
3414 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
3416 \line{\it addresses: \hfil}
3420 @c END TEXI2ROFF-KILL
3423 @section Assembler Internal Sections
3425 @cindex internal assembler sections
3426 @cindex sections in messages, internal
3427 These sections are meant only for the internal use of @command{@value{AS}}. They
3428 have no meaning at run-time. You do not really need to know about these
3429 sections for most purposes; but they can be mentioned in @command{@value{AS}}
3430 warning messages, so it might be helpful to have an idea of their
3431 meanings to @command{@value{AS}}. These sections are used to permit the
3432 value of every expression in your assembly language program to be a
3433 section-relative address.
3436 @cindex assembler internal logic error
3437 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
3438 An internal assembler logic error has been found. This means there is a
3439 bug in the assembler.
3441 @cindex expr (internal section)
3443 The assembler stores complex expression internally as combinations of
3444 symbols. When it needs to represent an expression as a symbol, it puts
3445 it in the expr section.
3447 @c FIXME item transfer[t] vector preload
3448 @c FIXME item transfer[t] vector postload
3449 @c FIXME item register
3453 @section Sub-Sections
3455 @cindex numbered subsections
3456 @cindex grouping data
3462 fall into two sections: text and data.
3464 You may have separate groups of
3466 data in named sections
3470 data in named sections
3476 that you want to end up near to each other in the object file, even though they
3477 are not contiguous in the assembler source. @command{@value{AS}} allows you to
3478 use @dfn{subsections} for this purpose. Within each section, there can be
3479 numbered subsections with values from 0 to 8192. Objects assembled into the
3480 same subsection go into the object file together with other objects in the same
3481 subsection. For example, a compiler might want to store constants in the text
3482 section, but might not want to have them interspersed with the program being
3483 assembled. In this case, the compiler could issue a @samp{.text 0} before each
3484 section of code being output, and a @samp{.text 1} before each group of
3485 constants being output.
3487 Subsections are optional. If you do not use subsections, everything
3488 goes in subsection number zero.
3491 Each subsection is zero-padded up to a multiple of four bytes.
3492 (Subsections may be padded a different amount on different flavors
3493 of @command{@value{AS}}.)
3497 On the H8/300 platform, each subsection is zero-padded to a word
3498 boundary (two bytes).
3499 The same is true on the Renesas SH.
3502 @c FIXME section padding (alignment)?
3503 @c Rich Pixley says padding here depends on target obj code format; that
3504 @c doesn't seem particularly useful to say without further elaboration,
3505 @c so for now I say nothing about it. If this is a generic BFD issue,
3506 @c these paragraphs might need to vanish from this manual, and be
3507 @c discussed in BFD chapter of binutils (or some such).
3511 Subsections appear in your object file in numeric order, lowest numbered
3512 to highest. (All this to be compatible with other people's assemblers.)
3513 The object file contains no representation of subsections; @code{@value{LD}} and
3514 other programs that manipulate object files see no trace of them.
3515 They just see all your text subsections as a text section, and all your
3516 data subsections as a data section.
3518 To specify which subsection you want subsequent statements assembled
3519 into, use a numeric argument to specify it, in a @samp{.text
3520 @var{expression}} or a @samp{.data @var{expression}} statement.
3523 When generating COFF output, you
3528 can also use an extra subsection
3529 argument with arbitrary named sections: @samp{.section @var{name},
3534 When generating ELF output, you
3539 can also use the @code{.subsection} directive (@pxref{SubSection})
3540 to specify a subsection: @samp{.subsection @var{expression}}.
3542 @var{Expression} should be an absolute expression
3543 (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0}
3544 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3545 begins in @code{text 0}. For instance:
3547 .text 0 # The default subsection is text 0 anyway.
3548 .ascii "This lives in the first text subsection. *"
3550 .ascii "But this lives in the second text subsection."
3552 .ascii "This lives in the data section,"
3553 .ascii "in the first data subsection."
3555 .ascii "This lives in the first text section,"
3556 .ascii "immediately following the asterisk (*)."
3559 Each section has a @dfn{location counter} incremented by one for every byte
3560 assembled into that section. Because subsections are merely a convenience
3561 restricted to @command{@value{AS}} there is no concept of a subsection location
3562 counter. There is no way to directly manipulate a location counter---but the
3563 @code{.align} directive changes it, and any label definition captures its
3564 current value. The location counter of the section where statements are being
3565 assembled is said to be the @dfn{active} location counter.
3568 @section bss Section
3571 @cindex common variable storage
3572 The bss section is used for local common variable storage.
3573 You may allocate address space in the bss section, but you may
3574 not dictate data to load into it before your program executes. When
3575 your program starts running, all the contents of the bss
3576 section are zeroed bytes.
3578 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3579 @ref{Lcomm,,@code{.lcomm}}.
3581 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3582 another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}.
3585 When assembling for a target which supports multiple sections, such as ELF or
3586 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3587 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3588 section. Typically the section will only contain symbol definitions and
3589 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3596 Symbols are a central concept: the programmer uses symbols to name
3597 things, the linker uses symbols to link, and the debugger uses symbols
3601 @cindex debuggers, and symbol order
3602 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3603 the same order they were declared. This may break some debuggers.
3608 * Setting Symbols:: Giving Symbols Other Values
3609 * Symbol Names:: Symbol Names
3610 * Dot:: The Special Dot Symbol
3611 * Symbol Attributes:: Symbol Attributes
3618 A @dfn{label} is written as a symbol immediately followed by a colon
3619 @samp{:}. The symbol then represents the current value of the
3620 active location counter, and is, for example, a suitable instruction
3621 operand. You are warned if you use the same symbol to represent two
3622 different locations: the first definition overrides any other
3626 On the HPPA, the usual form for a label need not be immediately followed by a
3627 colon, but instead must start in column zero. Only one label may be defined on
3628 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3629 provides a special directive @code{.label} for defining labels more flexibly.
3632 @node Setting Symbols
3633 @section Giving Symbols Other Values
3635 @cindex assigning values to symbols
3636 @cindex symbol values, assigning
3637 A symbol can be given an arbitrary value by writing a symbol, followed
3638 by an equals sign @samp{=}, followed by an expression
3639 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3640 directive. @xref{Set,,@code{.set}}. In the same way, using a double
3641 equals sign @samp{=}@samp{=} here represents an equivalent of the
3642 @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}.
3645 Blackfin does not support symbol assignment with @samp{=}.
3649 @section Symbol Names
3651 @cindex symbol names
3652 @cindex names, symbol
3653 @ifclear SPECIAL-SYMS
3654 Symbol names begin with a letter or with one of @samp{._}. On most
3655 machines, you can also use @code{$} in symbol names; exceptions are
3656 noted in @ref{Machine Dependencies}. That character may be followed by any
3657 string of digits, letters, dollar signs (unless otherwise noted for a
3658 particular target machine), and underscores.
3662 Symbol names begin with a letter or with one of @samp{._}. On the
3663 Renesas SH you can also use @code{$} in symbol names. That
3664 character may be followed by any string of digits, letters, dollar signs (save
3665 on the H8/300), and underscores.
3669 Case of letters is significant: @code{foo} is a different symbol name
3672 Symbol names do not start with a digit. An exception to this rule is made for
3673 Local Labels. See below.
3675 Multibyte characters are supported. To generate a symbol name containing
3676 multibyte characters enclose it within double quotes and use escape codes. cf
3677 @xref{Strings}. Generating a multibyte symbol name from a label is not
3678 currently supported.
3680 Each symbol has exactly one name. Each name in an assembly language program
3681 refers to exactly one symbol. You may use that symbol name any number of times
3684 @subheading Local Symbol Names
3686 @cindex local symbol names
3687 @cindex symbol names, local
3688 A local symbol is any symbol beginning with certain local label prefixes.
3689 By default, the local label prefix is @samp{.L} for ELF systems or
3690 @samp{L} for traditional a.out systems, but each target may have its own
3691 set of local label prefixes.
3693 On the HPPA local symbols begin with @samp{L$}.
3696 Local symbols are defined and used within the assembler, but they are
3697 normally not saved in object files. Thus, they are not visible when debugging.
3698 You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols})
3699 to retain the local symbols in the object files.
3701 @subheading Local Labels
3703 @cindex local labels
3704 @cindex temporary symbol names
3705 @cindex symbol names, temporary
3706 Local labels are different from local symbols. Local labels help compilers and
3707 programmers use names temporarily. They create symbols which are guaranteed to
3708 be unique over the entire scope of the input source code and which can be
3709 referred to by a simple notation. To define a local label, write a label of
3710 the form @samp{@b{N}:} (where @b{N} represents any non-negative integer).
3711 To refer to the most recent previous definition of that label write
3712 @samp{@b{N}b}, using the same number as when you defined the label. To refer
3713 to the next definition of a local label, write @samp{@b{N}f}. The @samp{b}
3714 stands for ``backwards'' and the @samp{f} stands for ``forwards''.
3716 There is no restriction on how you can use these labels, and you can reuse them
3717 too. So that it is possible to repeatedly define the same local label (using
3718 the same number @samp{@b{N}}), although you can only refer to the most recently
3719 defined local label of that number (for a backwards reference) or the next
3720 definition of a specific local label for a forward reference. It is also worth
3721 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3722 implemented in a slightly more efficient manner than the others.
3733 Which is the equivalent of:
3736 label_1: branch label_3
3737 label_2: branch label_1
3738 label_3: branch label_4
3739 label_4: branch label_3
3742 Local label names are only a notational device. They are immediately
3743 transformed into more conventional symbol names before the assembler uses them.
3744 The symbol names are stored in the symbol table, appear in error messages, and
3745 are optionally emitted to the object file. The names are constructed using
3749 @item @emph{local label prefix}
3750 All local symbols begin with the system-specific local label prefix.
3751 Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols
3752 that start with the local label prefix. These labels are
3753 used for symbols you are never intended to see. If you use the
3754 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3755 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3756 you may use them in debugging.
3759 This is the number that was used in the local label definition. So if the
3760 label is written @samp{55:} then the number is @samp{55}.
3763 This unusual character is included so you do not accidentally invent a symbol
3764 of the same name. The character has ASCII value of @samp{\002} (control-B).
3766 @item @emph{ordinal number}
3767 This is a serial number to keep the labels distinct. The first definition of
3768 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3769 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3770 the number @samp{1} and its 15th definition gets @samp{15} as well.
3773 So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and
3774 the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}.
3776 @subheading Dollar Local Labels
3777 @cindex dollar local symbols
3779 On some targets @code{@value{AS}} also supports an even more local form of
3780 local labels called dollar labels. These labels go out of scope (i.e., they
3781 become undefined) as soon as a non-local label is defined. Thus they remain
3782 valid for only a small region of the input source code. Normal local labels,
3783 by contrast, remain in scope for the entire file, or until they are redefined
3784 by another occurrence of the same local label.
3786 Dollar labels are defined in exactly the same way as ordinary local labels,
3787 except that they have a dollar sign suffix to their numeric value, e.g.,
3790 They can also be distinguished from ordinary local labels by their transformed
3791 names which use ASCII character @samp{\001} (control-A) as the magic character
3792 to distinguish them from ordinary labels. For example, the fifth definition of
3793 @samp{6$} may be named @samp{.L6@kbd{C-A}5}.
3796 @section The Special Dot Symbol
3798 @cindex dot (symbol)
3799 @cindex @code{.} (symbol)
3800 @cindex current address
3801 @cindex location counter
3802 The special symbol @samp{.} refers to the current address that
3803 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3804 .long .} defines @code{melvin} to contain its own address.
3805 Assigning a value to @code{.} is treated the same as a @code{.org}
3807 @ifclear no-space-dir
3808 Thus, the expression @samp{.=.+4} is the same as saying
3812 @node Symbol Attributes
3813 @section Symbol Attributes
3815 @cindex symbol attributes
3816 @cindex attributes, symbol
3817 Every symbol has, as well as its name, the attributes ``Value'' and
3818 ``Type''. Depending on output format, symbols can also have auxiliary
3821 The detailed definitions are in @file{a.out.h}.
3824 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3825 all these attributes, and probably won't warn you. This makes the
3826 symbol an externally defined symbol, which is generally what you
3830 * Symbol Value:: Value
3831 * Symbol Type:: Type
3834 * a.out Symbols:: Symbol Attributes: @code{a.out}
3838 * a.out Symbols:: Symbol Attributes: @code{a.out}
3841 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3846 * COFF Symbols:: Symbol Attributes for COFF
3849 * SOM Symbols:: Symbol Attributes for SOM
3856 @cindex value of a symbol
3857 @cindex symbol value
3858 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3859 location in the text, data, bss or absolute sections the value is the
3860 number of addresses from the start of that section to the label.
3861 Naturally for text, data and bss sections the value of a symbol changes
3862 as @code{@value{LD}} changes section base addresses during linking. Absolute
3863 symbols' values do not change during linking: that is why they are
3866 The value of an undefined symbol is treated in a special way. If it is
3867 0 then the symbol is not defined in this assembler source file, and
3868 @code{@value{LD}} tries to determine its value from other files linked into the
3869 same program. You make this kind of symbol simply by mentioning a symbol
3870 name without defining it. A non-zero value represents a @code{.comm}
3871 common declaration. The value is how much common storage to reserve, in
3872 bytes (addresses). The symbol refers to the first address of the
3878 @cindex type of a symbol
3880 The type attribute of a symbol contains relocation (section)
3881 information, any flag settings indicating that a symbol is external, and
3882 (optionally), other information for linkers and debuggers. The exact
3883 format depends on the object-code output format in use.
3888 @c The following avoids a "widow" subsection title. @group would be
3889 @c better if it were available outside examples.
3892 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3894 @cindex @code{b.out} symbol attributes
3895 @cindex symbol attributes, @code{b.out}
3896 These symbol attributes appear only when @command{@value{AS}} is configured for
3897 one of the Berkeley-descended object output formats---@code{a.out} or
3903 @subsection Symbol Attributes: @code{a.out}
3905 @cindex @code{a.out} symbol attributes
3906 @cindex symbol attributes, @code{a.out}
3912 @subsection Symbol Attributes: @code{a.out}
3914 @cindex @code{a.out} symbol attributes
3915 @cindex symbol attributes, @code{a.out}
3919 * Symbol Desc:: Descriptor
3920 * Symbol Other:: Other
3924 @subsubsection Descriptor
3926 @cindex descriptor, of @code{a.out} symbol
3927 This is an arbitrary 16-bit value. You may establish a symbol's
3928 descriptor value by using a @code{.desc} statement
3929 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3930 @command{@value{AS}}.
3933 @subsubsection Other
3935 @cindex other attribute, of @code{a.out} symbol
3936 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3941 @subsection Symbol Attributes for COFF
3943 @cindex COFF symbol attributes
3944 @cindex symbol attributes, COFF
3946 The COFF format supports a multitude of auxiliary symbol attributes;
3947 like the primary symbol attributes, they are set between @code{.def} and
3948 @code{.endef} directives.
3950 @subsubsection Primary Attributes
3952 @cindex primary attributes, COFF symbols
3953 The symbol name is set with @code{.def}; the value and type,
3954 respectively, with @code{.val} and @code{.type}.
3956 @subsubsection Auxiliary Attributes
3958 @cindex auxiliary attributes, COFF symbols
3959 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3960 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3961 table information for COFF.
3966 @subsection Symbol Attributes for SOM
3968 @cindex SOM symbol attributes
3969 @cindex symbol attributes, SOM
3971 The SOM format for the HPPA supports a multitude of symbol attributes set with
3972 the @code{.EXPORT} and @code{.IMPORT} directives.
3974 The attributes are described in @cite{HP9000 Series 800 Assembly
3975 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3976 @code{EXPORT} assembler directive documentation.
3980 @chapter Expressions
3984 @cindex numeric values
3985 An @dfn{expression} specifies an address or numeric value.
3986 Whitespace may precede and/or follow an expression.
3988 The result of an expression must be an absolute number, or else an offset into
3989 a particular section. If an expression is not absolute, and there is not
3990 enough information when @command{@value{AS}} sees the expression to know its
3991 section, a second pass over the source program might be necessary to interpret
3992 the expression---but the second pass is currently not implemented.
3993 @command{@value{AS}} aborts with an error message in this situation.
3996 * Empty Exprs:: Empty Expressions
3997 * Integer Exprs:: Integer Expressions
4001 @section Empty Expressions
4003 @cindex empty expressions
4004 @cindex expressions, empty
4005 An empty expression has no value: it is just whitespace or null.
4006 Wherever an absolute expression is required, you may omit the
4007 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
4008 is compatible with other assemblers.
4011 @section Integer Expressions
4013 @cindex integer expressions
4014 @cindex expressions, integer
4015 An @dfn{integer expression} is one or more @emph{arguments} delimited
4016 by @emph{operators}.
4019 * Arguments:: Arguments
4020 * Operators:: Operators
4021 * Prefix Ops:: Prefix Operators
4022 * Infix Ops:: Infix Operators
4026 @subsection Arguments
4028 @cindex expression arguments
4029 @cindex arguments in expressions
4030 @cindex operands in expressions
4031 @cindex arithmetic operands
4032 @dfn{Arguments} are symbols, numbers or subexpressions. In other
4033 contexts arguments are sometimes called ``arithmetic operands''. In
4034 this manual, to avoid confusing them with the ``instruction operands'' of
4035 the machine language, we use the term ``argument'' to refer to parts of
4036 expressions only, reserving the word ``operand'' to refer only to machine
4037 instruction operands.
4039 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
4040 @var{section} is one of text, data, bss, absolute,
4041 or undefined. @var{NNN} is a signed, 2's complement 32 bit
4044 Numbers are usually integers.
4046 A number can be a flonum or bignum. In this case, you are warned
4047 that only the low order 32 bits are used, and @command{@value{AS}} pretends
4048 these 32 bits are an integer. You may write integer-manipulating
4049 instructions that act on exotic constants, compatible with other
4052 @cindex subexpressions
4053 Subexpressions are a left parenthesis @samp{(} followed by an integer
4054 expression, followed by a right parenthesis @samp{)}; or a prefix
4055 operator followed by an argument.
4058 @subsection Operators
4060 @cindex operators, in expressions
4061 @cindex arithmetic functions
4062 @cindex functions, in expressions
4063 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
4064 operators are followed by an argument. Infix operators appear
4065 between their arguments. Operators may be preceded and/or followed by
4069 @subsection Prefix Operator
4071 @cindex prefix operators
4072 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
4073 one argument, which must be absolute.
4075 @c the tex/end tex stuff surrounding this small table is meant to make
4076 @c it align, on the printed page, with the similar table in the next
4077 @c section (which is inside an enumerate).
4079 \global\advance\leftskip by \itemindent
4084 @dfn{Negation}. Two's complement negation.
4086 @dfn{Complementation}. Bitwise not.
4090 \global\advance\leftskip by -\itemindent
4094 @subsection Infix Operators
4096 @cindex infix operators
4097 @cindex operators, permitted arguments
4098 @dfn{Infix operators} take two arguments, one on either side. Operators
4099 have precedence, but operations with equal precedence are performed left
4100 to right. Apart from @code{+} or @option{-}, both arguments must be
4101 absolute, and the result is absolute.
4104 @cindex operator precedence
4105 @cindex precedence of operators
4112 @dfn{Multiplication}.
4115 @dfn{Division}. Truncation is the same as the C operator @samp{/}
4121 @dfn{Shift Left}. Same as the C operator @samp{<<}.
4124 @dfn{Shift Right}. Same as the C operator @samp{>>}.
4128 Intermediate precedence
4133 @dfn{Bitwise Inclusive Or}.
4139 @dfn{Bitwise Exclusive Or}.
4142 @dfn{Bitwise Or Not}.
4149 @cindex addition, permitted arguments
4150 @cindex plus, permitted arguments
4151 @cindex arguments for addition
4153 @dfn{Addition}. If either argument is absolute, the result has the section of
4154 the other argument. You may not add together arguments from different
4157 @cindex subtraction, permitted arguments
4158 @cindex minus, permitted arguments
4159 @cindex arguments for subtraction
4161 @dfn{Subtraction}. If the right argument is absolute, the
4162 result has the section of the left argument.
4163 If both arguments are in the same section, the result is absolute.
4164 You may not subtract arguments from different sections.
4165 @c FIXME is there still something useful to say about undefined - undefined ?
4167 @cindex comparison expressions
4168 @cindex expressions, comparison
4173 @dfn{Is Not Equal To}
4177 @dfn{Is Greater Than}
4179 @dfn{Is Greater Than Or Equal To}
4181 @dfn{Is Less Than Or Equal To}
4183 The comparison operators can be used as infix operators. A true results has a
4184 value of -1 whereas a false result has a value of 0. Note, these operators
4185 perform signed comparisons.
4188 @item Lowest Precedence
4197 These two logical operations can be used to combine the results of sub
4198 expressions. Note, unlike the comparison operators a true result returns a
4199 value of 1 but a false results does still return 0. Also note that the logical
4200 or operator has a slightly lower precedence than logical and.
4205 In short, it's only meaningful to add or subtract the @emph{offsets} in an
4206 address; you can only have a defined section in one of the two arguments.
4209 @chapter Assembler Directives
4211 @cindex directives, machine independent
4212 @cindex pseudo-ops, machine independent
4213 @cindex machine independent directives
4214 All assembler directives have names that begin with a period (@samp{.}).
4215 The names are case insensitive for most targets, and usually written
4218 This chapter discusses directives that are available regardless of the
4219 target machine configuration for the @sc{gnu} assembler.
4221 Some machine configurations provide additional directives.
4222 @xref{Machine Dependencies}.
4225 @ifset machine-directives
4226 @xref{Machine Dependencies}, for additional directives.
4231 * Abort:: @code{.abort}
4233 * ABORT (COFF):: @code{.ABORT}
4236 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
4237 * Altmacro:: @code{.altmacro}
4238 * Ascii:: @code{.ascii "@var{string}"}@dots{}
4239 * Asciz:: @code{.asciz "@var{string}"}@dots{}
4240 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
4241 * Bundle directives:: @code{.bundle_align_mode @var{abs-expr}}, etc
4242 * Byte:: @code{.byte @var{expressions}}
4243 * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
4244 * Comm:: @code{.comm @var{symbol} , @var{length} }
4245 * Data:: @code{.data @var{subsection}}
4247 * Def:: @code{.def @var{name}}
4250 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
4256 * Double:: @code{.double @var{flonums}}
4257 * Eject:: @code{.eject}
4258 * Else:: @code{.else}
4259 * Elseif:: @code{.elseif}
4262 * Endef:: @code{.endef}
4265 * Endfunc:: @code{.endfunc}
4266 * Endif:: @code{.endif}
4267 * Equ:: @code{.equ @var{symbol}, @var{expression}}
4268 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
4269 * Eqv:: @code{.eqv @var{symbol}, @var{expression}}
4271 * Error:: @code{.error @var{string}}
4272 * Exitm:: @code{.exitm}
4273 * Extern:: @code{.extern}
4274 * Fail:: @code{.fail}
4275 * File:: @code{.file}
4276 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
4277 * Float:: @code{.float @var{flonums}}
4278 * Func:: @code{.func}
4279 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4281 * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
4282 * Hidden:: @code{.hidden @var{names}}
4285 * hword:: @code{.hword @var{expressions}}
4286 * Ident:: @code{.ident}
4287 * If:: @code{.if @var{absolute expression}}
4288 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4289 * Include:: @code{.include "@var{file}"}
4290 * Int:: @code{.int @var{expressions}}
4292 * Internal:: @code{.internal @var{names}}
4295 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
4296 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
4297 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
4298 * Lflags:: @code{.lflags}
4299 @ifclear no-line-dir
4300 * Line:: @code{.line @var{line-number}}
4303 * Linkonce:: @code{.linkonce [@var{type}]}
4304 * List:: @code{.list}
4305 * Ln:: @code{.ln @var{line-number}}
4306 * Loc:: @code{.loc @var{fileno} @var{lineno}}
4307 * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}}
4309 * Local:: @code{.local @var{names}}
4312 * Long:: @code{.long @var{expressions}}
4314 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
4317 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
4318 * MRI:: @code{.mri @var{val}}
4319 * Noaltmacro:: @code{.noaltmacro}
4320 * Nolist:: @code{.nolist}
4321 * Octa:: @code{.octa @var{bignums}}
4322 * Offset:: @code{.offset @var{loc}}
4323 * Org:: @code{.org @var{new-lc}, @var{fill}}
4324 * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4326 * PopSection:: @code{.popsection}
4327 * Previous:: @code{.previous}
4330 * Print:: @code{.print @var{string}}
4332 * Protected:: @code{.protected @var{names}}
4335 * Psize:: @code{.psize @var{lines}, @var{columns}}
4336 * Purgem:: @code{.purgem @var{name}}
4338 * PushSection:: @code{.pushsection @var{name}}
4341 * Quad:: @code{.quad @var{bignums}}
4342 * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
4343 * Rept:: @code{.rept @var{count}}
4344 * Sbttl:: @code{.sbttl "@var{subheading}"}
4346 * Scl:: @code{.scl @var{class}}
4349 * Section:: @code{.section @var{name}[, @var{flags}]}
4352 * Set:: @code{.set @var{symbol}, @var{expression}}
4353 * Short:: @code{.short @var{expressions}}
4354 * Single:: @code{.single @var{flonums}}
4356 * Size:: @code{.size [@var{name} , @var{expression}]}
4358 @ifclear no-space-dir
4359 * Skip:: @code{.skip @var{size} , @var{fill}}
4362 * Sleb128:: @code{.sleb128 @var{expressions}}
4363 @ifclear no-space-dir
4364 * Space:: @code{.space @var{size} , @var{fill}}
4367 * Stab:: @code{.stabd, .stabn, .stabs}
4370 * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
4371 * Struct:: @code{.struct @var{expression}}
4373 * SubSection:: @code{.subsection}
4374 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
4378 * Tag:: @code{.tag @var{structname}}
4381 * Text:: @code{.text @var{subsection}}
4382 * Title:: @code{.title "@var{heading}"}
4384 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
4387 * Uleb128:: @code{.uleb128 @var{expressions}}
4389 * Val:: @code{.val @var{addr}}
4393 * Version:: @code{.version "@var{string}"}
4394 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
4395 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
4398 * Warning:: @code{.warning @var{string}}
4399 * Weak:: @code{.weak @var{names}}
4400 * Weakref:: @code{.weakref @var{alias}, @var{symbol}}
4401 * Word:: @code{.word @var{expressions}}
4402 @ifclear no-space-dir
4403 * Zero:: @code{.zero @var{size}}
4405 * Deprecated:: Deprecated Directives
4409 @section @code{.abort}
4411 @cindex @code{abort} directive
4412 @cindex stopping the assembly
4413 This directive stops the assembly immediately. It is for
4414 compatibility with other assemblers. The original idea was that the
4415 assembly language source would be piped into the assembler. If the sender
4416 of the source quit, it could use this directive tells @command{@value{AS}} to
4417 quit also. One day @code{.abort} will not be supported.
4421 @section @code{.ABORT} (COFF)
4423 @cindex @code{ABORT} directive
4424 When producing COFF output, @command{@value{AS}} accepts this directive as a
4425 synonym for @samp{.abort}.
4428 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
4434 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4436 @cindex padding the location counter
4437 @cindex @code{align} directive
4438 Pad the location counter (in the current subsection) to a particular storage
4439 boundary. The first expression (which must be absolute) is the alignment
4440 required, as described below.
4442 The second expression (also absolute) gives the fill value to be stored in the
4443 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4444 padding bytes are normally zero. However, on some systems, if the section is
4445 marked as containing code and the fill value is omitted, the space is filled
4446 with no-op instructions.
4448 The third expression is also absolute, and is also optional. If it is present,
4449 it is the maximum number of bytes that should be skipped by this alignment
4450 directive. If doing the alignment would require skipping more bytes than the
4451 specified maximum, then the alignment is not done at all. You can omit the
4452 fill value (the second argument) entirely by simply using two commas after the
4453 required alignment; this can be useful if you want the alignment to be filled
4454 with no-op instructions when appropriate.
4456 The way the required alignment is specified varies from system to system.
4457 For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or1k,
4458 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
4459 alignment request in bytes. For example @samp{.align 8} advances
4460 the location counter until it is a multiple of 8. If the location counter
4461 is already a multiple of 8, no change is needed. For the tic54x, the
4462 first expression is the alignment request in words.
4464 For other systems, including ppc, i386 using a.out format, arm and
4465 strongarm, it is the
4466 number of low-order zero bits the location counter must have after
4467 advancement. For example @samp{.align 3} advances the location
4468 counter until it a multiple of 8. If the location counter is already a
4469 multiple of 8, no change is needed.
4471 This inconsistency is due to the different behaviors of the various
4472 native assemblers for these systems which GAS must emulate.
4473 GAS also provides @code{.balign} and @code{.p2align} directives,
4474 described later, which have a consistent behavior across all
4475 architectures (but are specific to GAS).
4478 @section @code{.altmacro}
4479 Enable alternate macro mode, enabling:
4482 @item LOCAL @var{name} [ , @dots{} ]
4483 One additional directive, @code{LOCAL}, is available. It is used to
4484 generate a string replacement for each of the @var{name} arguments, and
4485 replace any instances of @var{name} in each macro expansion. The
4486 replacement string is unique in the assembly, and different for each
4487 separate macro expansion. @code{LOCAL} allows you to write macros that
4488 define symbols, without fear of conflict between separate macro expansions.
4490 @item String delimiters
4491 You can write strings delimited in these other ways besides
4492 @code{"@var{string}"}:
4495 @item '@var{string}'
4496 You can delimit strings with single-quote characters.
4498 @item <@var{string}>
4499 You can delimit strings with matching angle brackets.
4502 @item single-character string escape
4503 To include any single character literally in a string (even if the
4504 character would otherwise have some special meaning), you can prefix the
4505 character with @samp{!} (an exclamation mark). For example, you can
4506 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4508 @item Expression results as strings
4509 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4510 and use the result as a string.
4514 @section @code{.ascii "@var{string}"}@dots{}
4516 @cindex @code{ascii} directive
4517 @cindex string literals
4518 @code{.ascii} expects zero or more string literals (@pxref{Strings})
4519 separated by commas. It assembles each string (with no automatic
4520 trailing zero byte) into consecutive addresses.
4523 @section @code{.asciz "@var{string}"}@dots{}
4525 @cindex @code{asciz} directive
4526 @cindex zero-terminated strings
4527 @cindex null-terminated strings
4528 @code{.asciz} is just like @code{.ascii}, but each string is followed by
4529 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
4532 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4534 @cindex padding the location counter given number of bytes
4535 @cindex @code{balign} directive
4536 Pad the location counter (in the current subsection) to a particular
4537 storage boundary. The first expression (which must be absolute) is the
4538 alignment request in bytes. For example @samp{.balign 8} advances
4539 the location counter until it is a multiple of 8. If the location counter
4540 is already a multiple of 8, no change is needed.
4542 The second expression (also absolute) gives the fill value to be stored in the
4543 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4544 padding bytes are normally zero. However, on some systems, if the section is
4545 marked as containing code and the fill value is omitted, the space is filled
4546 with no-op instructions.
4548 The third expression is also absolute, and is also optional. If it is present,
4549 it is the maximum number of bytes that should be skipped by this alignment
4550 directive. If doing the alignment would require skipping more bytes than the
4551 specified maximum, then the alignment is not done at all. You can omit the
4552 fill value (the second argument) entirely by simply using two commas after the
4553 required alignment; this can be useful if you want the alignment to be filled
4554 with no-op instructions when appropriate.
4556 @cindex @code{balignw} directive
4557 @cindex @code{balignl} directive
4558 The @code{.balignw} and @code{.balignl} directives are variants of the
4559 @code{.balign} directive. The @code{.balignw} directive treats the fill
4560 pattern as a two byte word value. The @code{.balignl} directives treats the
4561 fill pattern as a four byte longword value. For example, @code{.balignw
4562 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4563 filled in with the value 0x368d (the exact placement of the bytes depends upon
4564 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4567 @node Bundle directives
4568 @section Bundle directives
4569 @subsection @code{.bundle_align_mode @var{abs-expr}}
4570 @cindex @code{bundle_align_mode} directive
4572 @cindex instruction bundle
4573 @cindex aligned instruction bundle
4574 @code{.bundle_align_mode} enables or disables @dfn{aligned instruction
4575 bundle} mode. In this mode, sequences of adjacent instructions are grouped
4576 into fixed-sized @dfn{bundles}. If the argument is zero, this mode is
4577 disabled (which is the default state). If the argument it not zero, it
4578 gives the size of an instruction bundle as a power of two (as for the
4579 @code{.p2align} directive, @pxref{P2align}).
4581 For some targets, it's an ABI requirement that no instruction may span a
4582 certain aligned boundary. A @dfn{bundle} is simply a sequence of
4583 instructions that starts on an aligned boundary. For example, if
4584 @var{abs-expr} is @code{5} then the bundle size is 32, so each aligned
4585 chunk of 32 bytes is a bundle. When aligned instruction bundle mode is in
4586 effect, no single instruction may span a boundary between bundles. If an
4587 instruction would start too close to the end of a bundle for the length of
4588 that particular instruction to fit within the bundle, then the space at the
4589 end of that bundle is filled with no-op instructions so the instruction
4590 starts in the next bundle. As a corollary, it's an error if any single
4591 instruction's encoding is longer than the bundle size.
4593 @subsection @code{.bundle_lock} and @code{.bundle_unlock}
4594 @cindex @code{bundle_lock} directive
4595 @cindex @code{bundle_unlock} directive
4596 The @code{.bundle_lock} and directive @code{.bundle_unlock} directives
4597 allow explicit control over instruction bundle padding. These directives
4598 are only valid when @code{.bundle_align_mode} has been used to enable
4599 aligned instruction bundle mode. It's an error if they appear when
4600 @code{.bundle_align_mode} has not been used at all, or when the last
4601 directive was @w{@code{.bundle_align_mode 0}}.
4603 @cindex bundle-locked
4604 For some targets, it's an ABI requirement that certain instructions may
4605 appear only as part of specified permissible sequences of multiple
4606 instructions, all within the same bundle. A pair of @code{.bundle_lock}
4607 and @code{.bundle_unlock} directives define a @dfn{bundle-locked}
4608 instruction sequence. For purposes of aligned instruction bundle mode, a
4609 sequence starting with @code{.bundle_lock} and ending with
4610 @code{.bundle_unlock} is treated as a single instruction. That is, the
4611 entire sequence must fit into a single bundle and may not span a bundle
4612 boundary. If necessary, no-op instructions will be inserted before the
4613 first instruction of the sequence so that the whole sequence starts on an
4614 aligned bundle boundary. It's an error if the sequence is longer than the
4617 For convenience when using @code{.bundle_lock} and @code{.bundle_unlock}
4618 inside assembler macros (@pxref{Macro}), bundle-locked sequences may be
4619 nested. That is, a second @code{.bundle_lock} directive before the next
4620 @code{.bundle_unlock} directive has no effect except that it must be
4621 matched by another closing @code{.bundle_unlock} so that there is the
4622 same number of @code{.bundle_lock} and @code{.bundle_unlock} directives.
4625 @section @code{.byte @var{expressions}}
4627 @cindex @code{byte} directive
4628 @cindex integers, one byte
4629 @code{.byte} expects zero or more expressions, separated by commas.
4630 Each expression is assembled into the next byte.
4632 @node CFI directives
4633 @section CFI directives
4634 @subsection @code{.cfi_sections @var{section_list}}
4635 @cindex @code{cfi_sections} directive
4636 @code{.cfi_sections} may be used to specify whether CFI directives
4637 should emit @code{.eh_frame} section and/or @code{.debug_frame} section.
4638 If @var{section_list} is @code{.eh_frame}, @code{.eh_frame} is emitted,
4639 if @var{section_list} is @code{.debug_frame}, @code{.debug_frame} is emitted.
4640 To emit both use @code{.eh_frame, .debug_frame}. The default if this
4641 directive is not used is @code{.cfi_sections .eh_frame}.
4643 On targets that support compact unwinding tables these can be generated
4644 by specifying @code{.eh_frame_entry} instead of @code{.eh_frame}.
4646 @subsection @code{.cfi_startproc [simple]}
4647 @cindex @code{cfi_startproc} directive
4648 @code{.cfi_startproc} is used at the beginning of each function that
4649 should have an entry in @code{.eh_frame}. It initializes some internal
4650 data structures. Don't forget to close the function by
4651 @code{.cfi_endproc}.
4653 Unless @code{.cfi_startproc} is used along with parameter @code{simple}
4654 it also emits some architecture dependent initial CFI instructions.
4656 @subsection @code{.cfi_endproc}
4657 @cindex @code{cfi_endproc} directive
4658 @code{.cfi_endproc} is used at the end of a function where it closes its
4659 unwind entry previously opened by
4660 @code{.cfi_startproc}, and emits it to @code{.eh_frame}.
4662 @subsection @code{.cfi_personality @var{encoding} [, @var{exp}]}
4663 @cindex @code{cfi_personality} directive
4664 @code{.cfi_personality} defines personality routine and its encoding.
4665 @var{encoding} must be a constant determining how the personality
4666 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4667 argument is not present, otherwise second argument should be
4668 a constant or a symbol name. When using indirect encodings,
4669 the symbol provided should be the location where personality
4670 can be loaded from, not the personality routine itself.
4671 The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff},
4672 no personality routine.
4674 @subsection @code{.cfi_personality_id @var{id}}
4675 @cindex @code{cfi_personality_id} directive
4676 @code{cfi_personality_id} defines a personality routine by its index as
4677 defined in a compact unwinding format.
4678 Only valid when generating compact EH frames (i.e.
4679 with @code{.cfi_sections eh_frame_entry}.
4681 @subsection @code{.cfi_fde_data [@var{opcode1} [, @dots{}]]}
4682 @cindex @code{cfi_fde_data} directive
4683 @code{cfi_fde_data} is used to describe the compact unwind opcodes to be
4684 used for the current function. These are emitted inline in the
4685 @code{.eh_frame_entry} section if small enough and there is no LSDA, or
4686 in the @code{.gnu.extab} section otherwise.
4687 Only valid when generating compact EH frames (i.e.
4688 with @code{.cfi_sections eh_frame_entry}.
4690 @subsection @code{.cfi_lsda @var{encoding} [, @var{exp}]}
4691 @code{.cfi_lsda} defines LSDA and its encoding.
4692 @var{encoding} must be a constant determining how the LSDA
4693 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), the second
4694 argument is not present, otherwise the second argument should be a constant
4695 or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff},
4696 meaning that no LSDA is present.
4698 @subsection @code{.cfi_inline_lsda} [@var{align}]
4699 @code{.cfi_inline_lsda} marks the start of a LSDA data section and
4700 switches to the corresponding @code{.gnu.extab} section.
4701 Must be preceded by a CFI block containing a @code{.cfi_lsda} directive.
4702 Only valid when generating compact EH frames (i.e.
4703 with @code{.cfi_sections eh_frame_entry}.
4705 The table header and unwinding opcodes will be generated at this point,
4706 so that they are immediately followed by the LSDA data. The symbol
4707 referenced by the @code{.cfi_lsda} directive should still be defined
4708 in case a fallback FDE based encoding is used. The LSDA data is terminated
4709 by a section directive.
4711 The optional @var{align} argument specifies the alignment required.
4712 The alignment is specified as a power of two, as with the
4713 @code{.p2align} directive.
4715 @subsection @code{.cfi_def_cfa @var{register}, @var{offset}}
4716 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4717 address from @var{register} and add @var{offset} to it}.
4719 @subsection @code{.cfi_def_cfa_register @var{register}}
4720 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4721 now on @var{register} will be used instead of the old one. Offset
4724 @subsection @code{.cfi_def_cfa_offset @var{offset}}
4725 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4726 remains the same, but @var{offset} is new. Note that it is the
4727 absolute offset that will be added to a defined register to compute
4730 @subsection @code{.cfi_adjust_cfa_offset @var{offset}}
4731 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4732 value that is added/substracted from the previous offset.
4734 @subsection @code{.cfi_offset @var{register}, @var{offset}}
4735 Previous value of @var{register} is saved at offset @var{offset} from
4738 @subsection @code{.cfi_rel_offset @var{register}, @var{offset}}
4739 Previous value of @var{register} is saved at offset @var{offset} from
4740 the current CFA register. This is transformed to @code{.cfi_offset}
4741 using the known displacement of the CFA register from the CFA.
4742 This is often easier to use, because the number will match the
4743 code it's annotating.
4745 @subsection @code{.cfi_register @var{register1}, @var{register2}}
4746 Previous value of @var{register1} is saved in register @var{register2}.
4748 @subsection @code{.cfi_restore @var{register}}
4749 @code{.cfi_restore} says that the rule for @var{register} is now the
4750 same as it was at the beginning of the function, after all initial
4751 instruction added by @code{.cfi_startproc} were executed.
4753 @subsection @code{.cfi_undefined @var{register}}
4754 From now on the previous value of @var{register} can't be restored anymore.
4756 @subsection @code{.cfi_same_value @var{register}}
4757 Current value of @var{register} is the same like in the previous frame,
4758 i.e. no restoration needed.
4760 @subsection @code{.cfi_remember_state},
4761 First save all current rules for all registers by @code{.cfi_remember_state},
4762 then totally screw them up by subsequent @code{.cfi_*} directives and when
4763 everything is hopelessly bad, use @code{.cfi_restore_state} to restore
4764 the previous saved state.
4766 @subsection @code{.cfi_return_column @var{register}}
4767 Change return column @var{register}, i.e. the return address is either
4768 directly in @var{register} or can be accessed by rules for @var{register}.
4770 @subsection @code{.cfi_signal_frame}
4771 Mark current function as signal trampoline.
4773 @subsection @code{.cfi_window_save}
4774 SPARC register window has been saved.
4776 @subsection @code{.cfi_escape} @var{expression}[, @dots{}]
4777 Allows the user to add arbitrary bytes to the unwind info. One
4778 might use this to add OS-specific CFI opcodes, or generic CFI
4779 opcodes that GAS does not yet support.
4781 @subsection @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}}
4782 The current value of @var{register} is @var{label}. The value of @var{label}
4783 will be encoded in the output file according to @var{encoding}; see the
4784 description of @code{.cfi_personality} for details on this encoding.
4786 The usefulness of equating a register to a fixed label is probably
4787 limited to the return address register. Here, it can be useful to
4788 mark a code segment that has only one return address which is reached
4789 by a direct branch and no copy of the return address exists in memory
4790 or another register.
4793 @section @code{.comm @var{symbol} , @var{length} }
4795 @cindex @code{comm} directive
4796 @cindex symbol, common
4797 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
4798 common symbol in one object file may be merged with a defined or common symbol
4799 of the same name in another object file. If @code{@value{LD}} does not see a
4800 definition for the symbol--just one or more common symbols--then it will
4801 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
4802 absolute expression. If @code{@value{LD}} sees multiple common symbols with
4803 the same name, and they do not all have the same size, it will allocate space
4804 using the largest size.
4807 When using ELF or (as a GNU extension) PE, the @code{.comm} directive takes
4808 an optional third argument. This is the desired alignment of the symbol,
4809 specified for ELF as a byte boundary (for example, an alignment of 16 means
4810 that the least significant 4 bits of the address should be zero), and for PE
4811 as a power of two (for example, an alignment of 5 means aligned to a 32-byte
4812 boundary). The alignment must be an absolute expression, and it must be a
4813 power of two. If @code{@value{LD}} allocates uninitialized memory for the
4814 common symbol, it will use the alignment when placing the symbol. If no
4815 alignment is specified, @command{@value{AS}} will set the alignment to the
4816 largest power of two less than or equal to the size of the symbol, up to a
4817 maximum of 16 on ELF, or the default section alignment of 4 on PE@footnote{This
4818 is not the same as the executable image file alignment controlled by @code{@value{LD}}'s
4819 @samp{--section-alignment} option; image file sections in PE are aligned to
4820 multiples of 4096, which is far too large an alignment for ordinary variables.
4821 It is rather the default alignment for (non-debug) sections within object
4822 (@samp{*.o}) files, which are less strictly aligned.}.
4826 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4827 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4831 @section @code{.data @var{subsection}}
4833 @cindex @code{data} directive
4834 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4835 end of the data subsection numbered @var{subsection} (which is an
4836 absolute expression). If @var{subsection} is omitted, it defaults
4841 @section @code{.def @var{name}}
4843 @cindex @code{def} directive
4844 @cindex COFF symbols, debugging
4845 @cindex debugging COFF symbols
4846 Begin defining debugging information for a symbol @var{name}; the
4847 definition extends until the @code{.endef} directive is encountered.
4850 This directive is only observed when @command{@value{AS}} is configured for COFF
4851 format output; when producing @code{b.out}, @samp{.def} is recognized,
4858 @section @code{.desc @var{symbol}, @var{abs-expression}}
4860 @cindex @code{desc} directive
4861 @cindex COFF symbol descriptor
4862 @cindex symbol descriptor, COFF
4863 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4864 to the low 16 bits of an absolute expression.
4867 The @samp{.desc} directive is not available when @command{@value{AS}} is
4868 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4869 object format. For the sake of compatibility, @command{@value{AS}} accepts
4870 it, but produces no output, when configured for COFF.
4876 @section @code{.dim}
4878 @cindex @code{dim} directive
4879 @cindex COFF auxiliary symbol information
4880 @cindex auxiliary symbol information, COFF
4881 This directive is generated by compilers to include auxiliary debugging
4882 information in the symbol table. It is only permitted inside
4883 @code{.def}/@code{.endef} pairs.
4886 @samp{.dim} is only meaningful when generating COFF format output; when
4887 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4893 @section @code{.double @var{flonums}}
4895 @cindex @code{double} directive
4896 @cindex floating point numbers (double)
4897 @code{.double} expects zero or more flonums, separated by commas. It
4898 assembles floating point numbers.
4900 The exact kind of floating point numbers emitted depends on how
4901 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4905 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4906 in @sc{ieee} format.
4911 @section @code{.eject}
4913 @cindex @code{eject} directive
4914 @cindex new page, in listings
4915 @cindex page, in listings
4916 @cindex listing control: new page
4917 Force a page break at this point, when generating assembly listings.
4920 @section @code{.else}
4922 @cindex @code{else} directive
4923 @code{.else} is part of the @command{@value{AS}} support for conditional
4924 assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section
4925 of code to be assembled if the condition for the preceding @code{.if}
4929 @section @code{.elseif}
4931 @cindex @code{elseif} directive
4932 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4933 assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new
4934 @code{.if} block that would otherwise fill the entire @code{.else} section.
4937 @section @code{.end}
4939 @cindex @code{end} directive
4940 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4941 process anything in the file past the @code{.end} directive.
4945 @section @code{.endef}
4947 @cindex @code{endef} directive
4948 This directive flags the end of a symbol definition begun with
4952 @samp{.endef} is only meaningful when generating COFF format output; if
4953 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4954 directive but ignores it.
4959 @section @code{.endfunc}
4960 @cindex @code{endfunc} directive
4961 @code{.endfunc} marks the end of a function specified with @code{.func}.
4964 @section @code{.endif}
4966 @cindex @code{endif} directive
4967 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4968 it marks the end of a block of code that is only assembled
4969 conditionally. @xref{If,,@code{.if}}.
4972 @section @code{.equ @var{symbol}, @var{expression}}
4974 @cindex @code{equ} directive
4975 @cindex assigning values to symbols
4976 @cindex symbols, assigning values to
4977 This directive sets the value of @var{symbol} to @var{expression}.
4978 It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}.
4981 The syntax for @code{equ} on the HPPA is
4982 @samp{@var{symbol} .equ @var{expression}}.
4986 The syntax for @code{equ} on the Z80 is
4987 @samp{@var{symbol} equ @var{expression}}.
4988 On the Z80 it is an eror if @var{symbol} is already defined,
4989 but the symbol is not protected from later redefinition.
4990 Compare @ref{Equiv}.
4994 @section @code{.equiv @var{symbol}, @var{expression}}
4995 @cindex @code{equiv} directive
4996 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4997 the assembler will signal an error if @var{symbol} is already defined. Note a
4998 symbol which has been referenced but not actually defined is considered to be
5001 Except for the contents of the error message, this is roughly equivalent to
5008 plus it protects the symbol from later redefinition.
5011 @section @code{.eqv @var{symbol}, @var{expression}}
5012 @cindex @code{eqv} directive
5013 The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to
5014 evaluate the expression or any part of it immediately. Instead each time
5015 the resulting symbol is used in an expression, a snapshot of its current
5019 @section @code{.err}
5020 @cindex @code{err} directive
5021 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
5022 message and, unless the @option{-Z} option was used, it will not generate an
5023 object file. This can be used to signal an error in conditionally compiled code.
5026 @section @code{.error "@var{string}"}
5027 @cindex error directive
5029 Similarly to @code{.err}, this directive emits an error, but you can specify a
5030 string that will be emitted as the error message. If you don't specify the
5031 message, it defaults to @code{".error directive invoked in source file"}.
5032 @xref{Errors, ,Error and Warning Messages}.
5035 .error "This code has not been assembled and tested."
5039 @section @code{.exitm}
5040 Exit early from the current macro definition. @xref{Macro}.
5043 @section @code{.extern}
5045 @cindex @code{extern} directive
5046 @code{.extern} is accepted in the source program---for compatibility
5047 with other assemblers---but it is ignored. @command{@value{AS}} treats
5048 all undefined symbols as external.
5051 @section @code{.fail @var{expression}}
5053 @cindex @code{fail} directive
5054 Generates an error or a warning. If the value of the @var{expression} is 500
5055 or more, @command{@value{AS}} will print a warning message. If the value is less
5056 than 500, @command{@value{AS}} will print an error message. The message will
5057 include the value of @var{expression}. This can occasionally be useful inside
5058 complex nested macros or conditional assembly.
5061 @section @code{.file}
5062 @cindex @code{file} directive
5064 @ifclear no-file-dir
5065 There are two different versions of the @code{.file} directive. Targets
5066 that support DWARF2 line number information use the DWARF2 version of
5067 @code{.file}. Other targets use the default version.
5069 @subheading Default Version
5071 @cindex logical file name
5072 @cindex file name, logical
5073 This version of the @code{.file} directive tells @command{@value{AS}} that we
5074 are about to start a new logical file. The syntax is:
5080 @var{string} is the new file name. In general, the filename is
5081 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
5082 to specify an empty file name, you must give the quotes--@code{""}. This
5083 statement may go away in future: it is only recognized to be compatible with
5084 old @command{@value{AS}} programs.
5086 @subheading DWARF2 Version
5089 When emitting DWARF2 line number information, @code{.file} assigns filenames
5090 to the @code{.debug_line} file name table. The syntax is:
5093 .file @var{fileno} @var{filename}
5096 The @var{fileno} operand should be a unique positive integer to use as the
5097 index of the entry in the table. The @var{filename} operand is a C string
5100 The detail of filename indices is exposed to the user because the filename
5101 table is shared with the @code{.debug_info} section of the DWARF2 debugging
5102 information, and thus the user must know the exact indices that table
5106 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
5108 @cindex @code{fill} directive
5109 @cindex writing patterns in memory
5110 @cindex patterns, writing in memory
5111 @var{repeat}, @var{size} and @var{value} are absolute expressions.
5112 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
5113 may be zero or more. @var{Size} may be zero or more, but if it is
5114 more than 8, then it is deemed to have the value 8, compatible with
5115 other people's assemblers. The contents of each @var{repeat} bytes
5116 is taken from an 8-byte number. The highest order 4 bytes are
5117 zero. The lowest order 4 bytes are @var{value} rendered in the
5118 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
5119 Each @var{size} bytes in a repetition is taken from the lowest order
5120 @var{size} bytes of this number. Again, this bizarre behavior is
5121 compatible with other people's assemblers.
5123 @var{size} and @var{value} are optional.
5124 If the second comma and @var{value} are absent, @var{value} is
5125 assumed zero. If the first comma and following tokens are absent,
5126 @var{size} is assumed to be 1.
5129 @section @code{.float @var{flonums}}
5131 @cindex floating point numbers (single)
5132 @cindex @code{float} directive
5133 This directive assembles zero or more flonums, separated by commas. It
5134 has the same effect as @code{.single}.
5136 The exact kind of floating point numbers emitted depends on how
5137 @command{@value{AS}} is configured.
5138 @xref{Machine Dependencies}.
5142 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
5143 in @sc{ieee} format.
5148 @section @code{.func @var{name}[,@var{label}]}
5149 @cindex @code{func} directive
5150 @code{.func} emits debugging information to denote function @var{name}, and
5151 is ignored unless the file is assembled with debugging enabled.
5152 Only @samp{--gstabs[+]} is currently supported.
5153 @var{label} is the entry point of the function and if omitted @var{name}
5154 prepended with the @samp{leading char} is used.
5155 @samp{leading char} is usually @code{_} or nothing, depending on the target.
5156 All functions are currently defined to have @code{void} return type.
5157 The function must be terminated with @code{.endfunc}.
5160 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
5162 @cindex @code{global} directive
5163 @cindex symbol, making visible to linker
5164 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
5165 @var{symbol} in your partial program, its value is made available to
5166 other partial programs that are linked with it. Otherwise,
5167 @var{symbol} takes its attributes from a symbol of the same name
5168 from another file linked into the same program.
5170 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
5171 compatibility with other assemblers.
5174 On the HPPA, @code{.global} is not always enough to make it accessible to other
5175 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
5176 @xref{HPPA Directives, ,HPPA Assembler Directives}.
5181 @section @code{.gnu_attribute @var{tag},@var{value}}
5182 Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
5185 @section @code{.hidden @var{names}}
5187 @cindex @code{hidden} directive
5189 This is one of the ELF visibility directives. The other two are
5190 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
5191 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5193 This directive overrides the named symbols default visibility (which is set by
5194 their binding: local, global or weak). The directive sets the visibility to
5195 @code{hidden} which means that the symbols are not visible to other components.
5196 Such symbols are always considered to be @code{protected} as well.
5200 @section @code{.hword @var{expressions}}
5202 @cindex @code{hword} directive
5203 @cindex integers, 16-bit
5204 @cindex numbers, 16-bit
5205 @cindex sixteen bit integers
5206 This expects zero or more @var{expressions}, and emits
5207 a 16 bit number for each.
5210 This directive is a synonym for @samp{.short}; depending on the target
5211 architecture, it may also be a synonym for @samp{.word}.
5215 This directive is a synonym for @samp{.short}.
5218 This directive is a synonym for both @samp{.short} and @samp{.word}.
5223 @section @code{.ident}
5225 @cindex @code{ident} directive
5227 This directive is used by some assemblers to place tags in object files. The
5228 behavior of this directive varies depending on the target. When using the
5229 a.out object file format, @command{@value{AS}} simply accepts the directive for
5230 source-file compatibility with existing assemblers, but does not emit anything
5231 for it. When using COFF, comments are emitted to the @code{.comment} or
5232 @code{.rdata} section, depending on the target. When using ELF, comments are
5233 emitted to the @code{.comment} section.
5236 @section @code{.if @var{absolute expression}}
5238 @cindex conditional assembly
5239 @cindex @code{if} directive
5240 @code{.if} marks the beginning of a section of code which is only
5241 considered part of the source program being assembled if the argument
5242 (which must be an @var{absolute expression}) is non-zero. The end of
5243 the conditional section of code must be marked by @code{.endif}
5244 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
5245 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
5246 If you have several conditions to check, @code{.elseif} may be used to avoid
5247 nesting blocks if/else within each subsequent @code{.else} block.
5249 The following variants of @code{.if} are also supported:
5251 @cindex @code{ifdef} directive
5252 @item .ifdef @var{symbol}
5253 Assembles the following section of code if the specified @var{symbol}
5254 has been defined. Note a symbol which has been referenced but not yet defined
5255 is considered to be undefined.
5257 @cindex @code{ifb} directive
5258 @item .ifb @var{text}
5259 Assembles the following section of code if the operand is blank (empty).
5261 @cindex @code{ifc} directive
5262 @item .ifc @var{string1},@var{string2}
5263 Assembles the following section of code if the two strings are the same. The
5264 strings may be optionally quoted with single quotes. If they are not quoted,
5265 the first string stops at the first comma, and the second string stops at the
5266 end of the line. Strings which contain whitespace should be quoted. The
5267 string comparison is case sensitive.
5269 @cindex @code{ifeq} directive
5270 @item .ifeq @var{absolute expression}
5271 Assembles the following section of code if the argument is zero.
5273 @cindex @code{ifeqs} directive
5274 @item .ifeqs @var{string1},@var{string2}
5275 Another form of @code{.ifc}. The strings must be quoted using double quotes.
5277 @cindex @code{ifge} directive
5278 @item .ifge @var{absolute expression}
5279 Assembles the following section of code if the argument is greater than or
5282 @cindex @code{ifgt} directive
5283 @item .ifgt @var{absolute expression}
5284 Assembles the following section of code if the argument is greater than zero.
5286 @cindex @code{ifle} directive
5287 @item .ifle @var{absolute expression}
5288 Assembles the following section of code if the argument is less than or equal
5291 @cindex @code{iflt} directive
5292 @item .iflt @var{absolute expression}
5293 Assembles the following section of code if the argument is less than zero.
5295 @cindex @code{ifnb} directive
5296 @item .ifnb @var{text}
5297 Like @code{.ifb}, but the sense of the test is reversed: this assembles the
5298 following section of code if the operand is non-blank (non-empty).
5300 @cindex @code{ifnc} directive
5301 @item .ifnc @var{string1},@var{string2}.
5302 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
5303 following section of code if the two strings are not the same.
5305 @cindex @code{ifndef} directive
5306 @cindex @code{ifnotdef} directive
5307 @item .ifndef @var{symbol}
5308 @itemx .ifnotdef @var{symbol}
5309 Assembles the following section of code if the specified @var{symbol}
5310 has not been defined. Both spelling variants are equivalent. Note a symbol
5311 which has been referenced but not yet defined is considered to be undefined.
5313 @cindex @code{ifne} directive
5314 @item .ifne @var{absolute expression}
5315 Assembles the following section of code if the argument is not equal to zero
5316 (in other words, this is equivalent to @code{.if}).
5318 @cindex @code{ifnes} directive
5319 @item .ifnes @var{string1},@var{string2}
5320 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
5321 following section of code if the two strings are not the same.
5325 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
5327 @cindex @code{incbin} directive
5328 @cindex binary files, including
5329 The @code{incbin} directive includes @var{file} verbatim at the current
5330 location. You can control the search paths used with the @samp{-I} command-line
5331 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5334 The @var{skip} argument skips a number of bytes from the start of the
5335 @var{file}. The @var{count} argument indicates the maximum number of bytes to
5336 read. Note that the data is not aligned in any way, so it is the user's
5337 responsibility to make sure that proper alignment is provided both before and
5338 after the @code{incbin} directive.
5341 @section @code{.include "@var{file}"}
5343 @cindex @code{include} directive
5344 @cindex supporting files, including
5345 @cindex files, including
5346 This directive provides a way to include supporting files at specified
5347 points in your source program. The code from @var{file} is assembled as
5348 if it followed the point of the @code{.include}; when the end of the
5349 included file is reached, assembly of the original file continues. You
5350 can control the search paths used with the @samp{-I} command-line option
5351 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5355 @section @code{.int @var{expressions}}
5357 @cindex @code{int} directive
5358 @cindex integers, 32-bit
5359 Expect zero or more @var{expressions}, of any section, separated by commas.
5360 For each expression, emit a number that, at run time, is the value of that
5361 expression. The byte order and bit size of the number depends on what kind
5362 of target the assembly is for.
5366 On most forms of the H8/300, @code{.int} emits 16-bit
5367 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
5374 @section @code{.internal @var{names}}
5376 @cindex @code{internal} directive
5378 This is one of the ELF visibility directives. The other two are
5379 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
5380 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5382 This directive overrides the named symbols default visibility (which is set by
5383 their binding: local, global or weak). The directive sets the visibility to
5384 @code{internal} which means that the symbols are considered to be @code{hidden}
5385 (i.e., not visible to other components), and that some extra, processor specific
5386 processing must also be performed upon the symbols as well.
5390 @section @code{.irp @var{symbol},@var{values}}@dots{}
5392 @cindex @code{irp} directive
5393 Evaluate a sequence of statements assigning different values to @var{symbol}.
5394 The sequence of statements starts at the @code{.irp} directive, and is
5395 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
5396 set to @var{value}, and the sequence of statements is assembled. If no
5397 @var{value} is listed, the sequence of statements is assembled once, with
5398 @var{symbol} set to the null string. To refer to @var{symbol} within the
5399 sequence of statements, use @var{\symbol}.
5401 For example, assembling
5409 is equivalent to assembling
5417 For some caveats with the spelling of @var{symbol}, see also @ref{Macro}.
5420 @section @code{.irpc @var{symbol},@var{values}}@dots{}
5422 @cindex @code{irpc} directive
5423 Evaluate a sequence of statements assigning different values to @var{symbol}.
5424 The sequence of statements starts at the @code{.irpc} directive, and is
5425 terminated by an @code{.endr} directive. For each character in @var{value},
5426 @var{symbol} is set to the character, and the sequence of statements is
5427 assembled. If no @var{value} is listed, the sequence of statements is
5428 assembled once, with @var{symbol} set to the null string. To refer to
5429 @var{symbol} within the sequence of statements, use @var{\symbol}.
5431 For example, assembling
5439 is equivalent to assembling
5447 For some caveats with the spelling of @var{symbol}, see also the discussion
5451 @section @code{.lcomm @var{symbol} , @var{length}}
5453 @cindex @code{lcomm} directive
5454 @cindex local common symbols
5455 @cindex symbols, local common
5456 Reserve @var{length} (an absolute expression) bytes for a local common
5457 denoted by @var{symbol}. The section and value of @var{symbol} are
5458 those of the new local common. The addresses are allocated in the bss
5459 section, so that at run-time the bytes start off zeroed. @var{Symbol}
5460 is not declared global (@pxref{Global,,@code{.global}}), so is normally
5461 not visible to @code{@value{LD}}.
5464 Some targets permit a third argument to be used with @code{.lcomm}. This
5465 argument specifies the desired alignment of the symbol in the bss section.
5469 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
5470 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
5474 @section @code{.lflags}
5476 @cindex @code{lflags} directive (ignored)
5477 @command{@value{AS}} accepts this directive, for compatibility with other
5478 assemblers, but ignores it.
5480 @ifclear no-line-dir
5482 @section @code{.line @var{line-number}}
5484 @cindex @code{line} directive
5485 @cindex logical line number
5487 Change the logical line number. @var{line-number} must be an absolute
5488 expression. The next line has that logical line number. Therefore any other
5489 statements on the current line (after a statement separator character) are
5490 reported as on logical line number @var{line-number} @minus{} 1. One day
5491 @command{@value{AS}} will no longer support this directive: it is recognized only
5492 for compatibility with existing assembler programs.
5495 Even though this is a directive associated with the @code{a.out} or
5496 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
5497 when producing COFF output, and treats @samp{.line} as though it
5498 were the COFF @samp{.ln} @emph{if} it is found outside a
5499 @code{.def}/@code{.endef} pair.
5501 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
5502 used by compilers to generate auxiliary symbol information for
5507 @section @code{.linkonce [@var{type}]}
5509 @cindex @code{linkonce} directive
5510 @cindex common sections
5511 Mark the current section so that the linker only includes a single copy of it.
5512 This may be used to include the same section in several different object files,
5513 but ensure that the linker will only include it once in the final output file.
5514 The @code{.linkonce} pseudo-op must be used for each instance of the section.
5515 Duplicate sections are detected based on the section name, so it should be
5518 This directive is only supported by a few object file formats; as of this
5519 writing, the only object file format which supports it is the Portable
5520 Executable format used on Windows NT.
5522 The @var{type} argument is optional. If specified, it must be one of the
5523 following strings. For example:
5527 Not all types may be supported on all object file formats.
5531 Silently discard duplicate sections. This is the default.
5534 Warn if there are duplicate sections, but still keep only one copy.
5537 Warn if any of the duplicates have different sizes.
5540 Warn if any of the duplicates do not have exactly the same contents.
5544 @section @code{.list}
5546 @cindex @code{list} directive
5547 @cindex listing control, turning on
5548 Control (in conjunction with the @code{.nolist} directive) whether or
5549 not assembly listings are generated. These two directives maintain an
5550 internal counter (which is zero initially). @code{.list} increments the
5551 counter, and @code{.nolist} decrements it. Assembly listings are
5552 generated whenever the counter is greater than zero.
5554 By default, listings are disabled. When you enable them (with the
5555 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
5556 the initial value of the listing counter is one.
5559 @section @code{.ln @var{line-number}}
5561 @cindex @code{ln} directive
5562 @ifclear no-line-dir
5563 @samp{.ln} is a synonym for @samp{.line}.
5566 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
5567 must be an absolute expression. The next line has that logical
5568 line number, so any other statements on the current line (after a
5569 statement separator character @code{;}) are reported as on logical
5570 line number @var{line-number} @minus{} 1.
5573 This directive is accepted, but ignored, when @command{@value{AS}} is
5574 configured for @code{b.out}; its effect is only associated with COFF
5580 @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]}
5581 @cindex @code{loc} directive
5582 When emitting DWARF2 line number information,
5583 the @code{.loc} directive will add a row to the @code{.debug_line} line
5584 number matrix corresponding to the immediately following assembly
5585 instruction. The @var{fileno}, @var{lineno}, and optional @var{column}
5586 arguments will be applied to the @code{.debug_line} state machine before
5589 The @var{options} are a sequence of the following tokens in any order:
5593 This option will set the @code{basic_block} register in the
5594 @code{.debug_line} state machine to @code{true}.
5597 This option will set the @code{prologue_end} register in the
5598 @code{.debug_line} state machine to @code{true}.
5600 @item epilogue_begin
5601 This option will set the @code{epilogue_begin} register in the
5602 @code{.debug_line} state machine to @code{true}.
5604 @item is_stmt @var{value}
5605 This option will set the @code{is_stmt} register in the
5606 @code{.debug_line} state machine to @code{value}, which must be
5609 @item isa @var{value}
5610 This directive will set the @code{isa} register in the @code{.debug_line}
5611 state machine to @var{value}, which must be an unsigned integer.
5613 @item discriminator @var{value}
5614 This directive will set the @code{discriminator} register in the @code{.debug_line}
5615 state machine to @var{value}, which must be an unsigned integer.
5619 @node Loc_mark_labels
5620 @section @code{.loc_mark_labels @var{enable}}
5621 @cindex @code{loc_mark_labels} directive
5622 When emitting DWARF2 line number information,
5623 the @code{.loc_mark_labels} directive makes the assembler emit an entry
5624 to the @code{.debug_line} line number matrix with the @code{basic_block}
5625 register in the state machine set whenever a code label is seen.
5626 The @var{enable} argument should be either 1 or 0, to enable or disable
5627 this function respectively.
5631 @section @code{.local @var{names}}
5633 @cindex @code{local} directive
5634 This directive, which is available for ELF targets, marks each symbol in
5635 the comma-separated list of @code{names} as a local symbol so that it
5636 will not be externally visible. If the symbols do not already exist,
5637 they will be created.
5639 For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not
5640 accept an alignment argument, which is the case for most ELF targets,
5641 the @code{.local} directive can be used in combination with @code{.comm}
5642 (@pxref{Comm}) to define aligned local common data.
5646 @section @code{.long @var{expressions}}
5648 @cindex @code{long} directive
5649 @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}.
5652 @c no one seems to know what this is for or whether this description is
5653 @c what it really ought to do
5655 @section @code{.lsym @var{symbol}, @var{expression}}
5657 @cindex @code{lsym} directive
5658 @cindex symbol, not referenced in assembly
5659 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
5660 the hash table, ensuring it cannot be referenced by name during the
5661 rest of the assembly. This sets the attributes of the symbol to be
5662 the same as the expression value:
5664 @var{other} = @var{descriptor} = 0
5665 @var{type} = @r{(section of @var{expression})}
5666 @var{value} = @var{expression}
5669 The new symbol is not flagged as external.
5673 @section @code{.macro}
5676 The commands @code{.macro} and @code{.endm} allow you to define macros that
5677 generate assembly output. For example, this definition specifies a macro
5678 @code{sum} that puts a sequence of numbers into memory:
5681 .macro sum from=0, to=5
5690 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
5702 @item .macro @var{macname}
5703 @itemx .macro @var{macname} @var{macargs} @dots{}
5704 @cindex @code{macro} directive
5705 Begin the definition of a macro called @var{macname}. If your macro
5706 definition requires arguments, specify their names after the macro name,
5707 separated by commas or spaces. You can qualify the macro argument to
5708 indicate whether all invocations must specify a non-blank value (through
5709 @samp{:@code{req}}), or whether it takes all of the remaining arguments
5710 (through @samp{:@code{vararg}}). You can supply a default value for any
5711 macro argument by following the name with @samp{=@var{deflt}}. You
5712 cannot define two macros with the same @var{macname} unless it has been
5713 subject to the @code{.purgem} directive (@pxref{Purgem}) between the two
5714 definitions. For example, these are all valid @code{.macro} statements:
5718 Begin the definition of a macro called @code{comm}, which takes no
5721 @item .macro plus1 p, p1
5722 @itemx .macro plus1 p p1
5723 Either statement begins the definition of a macro called @code{plus1},
5724 which takes two arguments; within the macro definition, write
5725 @samp{\p} or @samp{\p1} to evaluate the arguments.
5727 @item .macro reserve_str p1=0 p2
5728 Begin the definition of a macro called @code{reserve_str}, with two
5729 arguments. The first argument has a default value, but not the second.
5730 After the definition is complete, you can call the macro either as
5731 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
5732 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
5733 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
5734 @samp{0}, and @samp{\p2} evaluating to @var{b}).
5736 @item .macro m p1:req, p2=0, p3:vararg
5737 Begin the definition of a macro called @code{m}, with at least three
5738 arguments. The first argument must always have a value specified, but
5739 not the second, which instead has a default value. The third formal
5740 will get assigned all remaining arguments specified at invocation time.
5742 When you call a macro, you can specify the argument values either by
5743 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
5744 @samp{sum to=17, from=9}.
5748 Note that since each of the @var{macargs} can be an identifier exactly
5749 as any other one permitted by the target architecture, there may be
5750 occasional problems if the target hand-crafts special meanings to certain
5751 characters when they occur in a special position. For example, if the colon
5752 (@code{:}) is generally permitted to be part of a symbol name, but the
5753 architecture specific code special-cases it when occurring as the final
5754 character of a symbol (to denote a label), then the macro parameter
5755 replacement code will have no way of knowing that and consider the whole
5756 construct (including the colon) an identifier, and check only this
5757 identifier for being the subject to parameter substitution. So for example
5758 this macro definition:
5766 might not work as expected. Invoking @samp{label foo} might not create a label
5767 called @samp{foo} but instead just insert the text @samp{\l:} into the
5768 assembler source, probably generating an error about an unrecognised
5771 Similarly problems might occur with the period character (@samp{.})
5772 which is often allowed inside opcode names (and hence identifier names). So
5773 for example constructing a macro to build an opcode from a base name and a
5774 length specifier like this:
5777 .macro opcode base length
5782 and invoking it as @samp{opcode store l} will not create a @samp{store.l}
5783 instruction but instead generate some kind of error as the assembler tries to
5784 interpret the text @samp{\base.\length}.
5786 There are several possible ways around this problem:
5789 @item Insert white space
5790 If it is possible to use white space characters then this is the simplest
5799 @item Use @samp{\()}
5800 The string @samp{\()} can be used to separate the end of a macro argument from
5801 the following text. eg:
5804 .macro opcode base length
5809 @item Use the alternate macro syntax mode
5810 In the alternative macro syntax mode the ampersand character (@samp{&}) can be
5811 used as a separator. eg:
5821 Note: this problem of correctly identifying string parameters to pseudo ops
5822 also applies to the identifiers used in @code{.irp} (@pxref{Irp})
5823 and @code{.irpc} (@pxref{Irpc}) as well.
5826 @cindex @code{endm} directive
5827 Mark the end of a macro definition.
5830 @cindex @code{exitm} directive
5831 Exit early from the current macro definition.
5833 @cindex number of macros executed
5834 @cindex macros, count executed
5836 @command{@value{AS}} maintains a counter of how many macros it has
5837 executed in this pseudo-variable; you can copy that number to your
5838 output with @samp{\@@}, but @emph{only within a macro definition}.
5840 @item LOCAL @var{name} [ , @dots{} ]
5841 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
5842 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
5843 @xref{Altmacro,,@code{.altmacro}}.
5847 @section @code{.mri @var{val}}
5849 @cindex @code{mri} directive
5850 @cindex MRI mode, temporarily
5851 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
5852 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
5853 affects code assembled until the next @code{.mri} directive, or until the end
5854 of the file. @xref{M, MRI mode, MRI mode}.
5857 @section @code{.noaltmacro}
5858 Disable alternate macro mode. @xref{Altmacro}.
5861 @section @code{.nolist}
5863 @cindex @code{nolist} directive
5864 @cindex listing control, turning off
5865 Control (in conjunction with the @code{.list} directive) whether or
5866 not assembly listings are generated. These two directives maintain an
5867 internal counter (which is zero initially). @code{.list} increments the
5868 counter, and @code{.nolist} decrements it. Assembly listings are
5869 generated whenever the counter is greater than zero.
5872 @section @code{.octa @var{bignums}}
5874 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
5875 @cindex @code{octa} directive
5876 @cindex integer, 16-byte
5877 @cindex sixteen byte integer
5878 This directive expects zero or more bignums, separated by commas. For each
5879 bignum, it emits a 16-byte integer.
5881 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
5882 hence @emph{octa}-word for 16 bytes.
5885 @section @code{.offset @var{loc}}
5887 @cindex @code{offset} directive
5888 Set the location counter to @var{loc} in the absolute section. @var{loc} must
5889 be an absolute expression. This directive may be useful for defining
5890 symbols with absolute values. Do not confuse it with the @code{.org}
5894 @section @code{.org @var{new-lc} , @var{fill}}
5896 @cindex @code{org} directive
5897 @cindex location counter, advancing
5898 @cindex advancing location counter
5899 @cindex current address, advancing
5900 Advance the location counter of the current section to
5901 @var{new-lc}. @var{new-lc} is either an absolute expression or an
5902 expression with the same section as the current subsection. That is,
5903 you can't use @code{.org} to cross sections: if @var{new-lc} has the
5904 wrong section, the @code{.org} directive is ignored. To be compatible
5905 with former assemblers, if the section of @var{new-lc} is absolute,
5906 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
5907 is the same as the current subsection.
5909 @code{.org} may only increase the location counter, or leave it
5910 unchanged; you cannot use @code{.org} to move the location counter
5913 @c double negative used below "not undefined" because this is a specific
5914 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
5915 @c section. doc@cygnus.com 18feb91
5916 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
5917 may not be undefined. If you really detest this restriction we eagerly await
5918 a chance to share your improved assembler.
5920 Beware that the origin is relative to the start of the section, not
5921 to the start of the subsection. This is compatible with other
5922 people's assemblers.
5924 When the location counter (of the current subsection) is advanced, the
5925 intervening bytes are filled with @var{fill} which should be an
5926 absolute expression. If the comma and @var{fill} are omitted,
5927 @var{fill} defaults to zero.
5930 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
5932 @cindex padding the location counter given a power of two
5933 @cindex @code{p2align} directive
5934 Pad the location counter (in the current subsection) to a particular
5935 storage boundary. The first expression (which must be absolute) is the
5936 number of low-order zero bits the location counter must have after
5937 advancement. For example @samp{.p2align 3} advances the location
5938 counter until it a multiple of 8. If the location counter is already a
5939 multiple of 8, no change is needed.
5941 The second expression (also absolute) gives the fill value to be stored in the
5942 padding bytes. It (and the comma) may be omitted. If it is omitted, the
5943 padding bytes are normally zero. However, on some systems, if the section is
5944 marked as containing code and the fill value is omitted, the space is filled
5945 with no-op instructions.
5947 The third expression is also absolute, and is also optional. If it is present,
5948 it is the maximum number of bytes that should be skipped by this alignment
5949 directive. If doing the alignment would require skipping more bytes than the
5950 specified maximum, then the alignment is not done at all. You can omit the
5951 fill value (the second argument) entirely by simply using two commas after the
5952 required alignment; this can be useful if you want the alignment to be filled
5953 with no-op instructions when appropriate.
5955 @cindex @code{p2alignw} directive
5956 @cindex @code{p2alignl} directive
5957 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5958 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5959 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5960 fill pattern as a four byte longword value. For example, @code{.p2alignw
5961 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5962 filled in with the value 0x368d (the exact placement of the bytes depends upon
5963 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5968 @section @code{.popsection}
5970 @cindex @code{popsection} directive
5971 @cindex Section Stack
5972 This is one of the ELF section stack manipulation directives. The others are
5973 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5974 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5977 This directive replaces the current section (and subsection) with the top
5978 section (and subsection) on the section stack. This section is popped off the
5984 @section @code{.previous}
5986 @cindex @code{previous} directive
5987 @cindex Section Stack
5988 This is one of the ELF section stack manipulation directives. The others are
5989 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5990 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5991 (@pxref{PopSection}).
5993 This directive swaps the current section (and subsection) with most recently
5994 referenced section/subsection pair prior to this one. Multiple
5995 @code{.previous} directives in a row will flip between two sections (and their
5996 subsections). For example:
6008 Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
6014 # Now in section A subsection 1
6018 # Now in section B subsection 0
6021 # Now in section B subsection 1
6024 # Now in section B subsection 0
6028 Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
6029 section B and 0x9abc into subsection 1 of section B.
6031 In terms of the section stack, this directive swaps the current section with
6032 the top section on the section stack.
6036 @section @code{.print @var{string}}
6038 @cindex @code{print} directive
6039 @command{@value{AS}} will print @var{string} on the standard output during
6040 assembly. You must put @var{string} in double quotes.
6044 @section @code{.protected @var{names}}
6046 @cindex @code{protected} directive
6048 This is one of the ELF visibility directives. The other two are
6049 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
6051 This directive overrides the named symbols default visibility (which is set by
6052 their binding: local, global or weak). The directive sets the visibility to
6053 @code{protected} which means that any references to the symbols from within the
6054 components that defines them must be resolved to the definition in that
6055 component, even if a definition in another component would normally preempt
6060 @section @code{.psize @var{lines} , @var{columns}}
6062 @cindex @code{psize} directive
6063 @cindex listing control: paper size
6064 @cindex paper size, for listings
6065 Use this directive to declare the number of lines---and, optionally, the
6066 number of columns---to use for each page, when generating listings.
6068 If you do not use @code{.psize}, listings use a default line-count
6069 of 60. You may omit the comma and @var{columns} specification; the
6070 default width is 200 columns.
6072 @command{@value{AS}} generates formfeeds whenever the specified number of
6073 lines is exceeded (or whenever you explicitly request one, using
6076 If you specify @var{lines} as @code{0}, no formfeeds are generated save
6077 those explicitly specified with @code{.eject}.
6080 @section @code{.purgem @var{name}}
6082 @cindex @code{purgem} directive
6083 Undefine the macro @var{name}, so that later uses of the string will not be
6084 expanded. @xref{Macro}.
6088 @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]}
6090 @cindex @code{pushsection} directive
6091 @cindex Section Stack
6092 This is one of the ELF section stack manipulation directives. The others are
6093 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
6094 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6097 This directive pushes the current section (and subsection) onto the
6098 top of the section stack, and then replaces the current section and
6099 subsection with @code{name} and @code{subsection}. The optional
6100 @code{flags}, @code{type} and @code{arguments} are treated the same
6101 as in the @code{.section} (@pxref{Section}) directive.
6105 @section @code{.quad @var{bignums}}
6107 @cindex @code{quad} directive
6108 @code{.quad} expects zero or more bignums, separated by commas. For
6109 each bignum, it emits
6111 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
6112 warning message; and just takes the lowest order 8 bytes of the bignum.
6113 @cindex eight-byte integer
6114 @cindex integer, 8-byte
6116 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
6117 hence @emph{quad}-word for 8 bytes.
6120 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
6121 warning message; and just takes the lowest order 16 bytes of the bignum.
6122 @cindex sixteen-byte integer
6123 @cindex integer, 16-byte
6127 @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
6129 @cindex @code{reloc} directive
6130 Generate a relocation at @var{offset} of type @var{reloc_name} with value
6131 @var{expression}. If @var{offset} is a number, the relocation is generated in
6132 the current section. If @var{offset} is an expression that resolves to a
6133 symbol plus offset, the relocation is generated in the given symbol's section.
6134 @var{expression}, if present, must resolve to a symbol plus addend or to an
6135 absolute value, but note that not all targets support an addend. e.g. ELF REL
6136 targets such as i386 store an addend in the section contents rather than in the
6137 relocation. This low level interface does not support addends stored in the
6141 @section @code{.rept @var{count}}
6143 @cindex @code{rept} directive
6144 Repeat the sequence of lines between the @code{.rept} directive and the next
6145 @code{.endr} directive @var{count} times.
6147 For example, assembling
6155 is equivalent to assembling
6164 @section @code{.sbttl "@var{subheading}"}
6166 @cindex @code{sbttl} directive
6167 @cindex subtitles for listings
6168 @cindex listing control: subtitle
6169 Use @var{subheading} as the title (third line, immediately after the
6170 title line) when generating assembly listings.
6172 This directive affects subsequent pages, as well as the current page if
6173 it appears within ten lines of the top of a page.
6177 @section @code{.scl @var{class}}
6179 @cindex @code{scl} directive
6180 @cindex symbol storage class (COFF)
6181 @cindex COFF symbol storage class
6182 Set the storage-class value for a symbol. This directive may only be
6183 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
6184 whether a symbol is static or external, or it may record further
6185 symbolic debugging information.
6188 The @samp{.scl} directive is primarily associated with COFF output; when
6189 configured to generate @code{b.out} output format, @command{@value{AS}}
6190 accepts this directive but ignores it.
6196 @section @code{.section @var{name}}
6198 @cindex named section
6199 Use the @code{.section} directive to assemble the following code into a section
6202 This directive is only supported for targets that actually support arbitrarily
6203 named sections; on @code{a.out} targets, for example, it is not accepted, even
6204 with a standard @code{a.out} section name.
6208 @c only print the extra heading if both COFF and ELF are set
6209 @subheading COFF Version
6212 @cindex @code{section} directive (COFF version)
6213 For COFF targets, the @code{.section} directive is used in one of the following
6217 .section @var{name}[, "@var{flags}"]
6218 .section @var{name}[, @var{subsection}]
6221 If the optional argument is quoted, it is taken as flags to use for the
6222 section. Each flag is a single character. The following flags are recognized:
6225 bss section (uninitialized data)
6227 section is not loaded
6233 exclude section from linking
6239 shared section (meaningful for PE targets)
6241 ignored. (For compatibility with the ELF version)
6243 section is not readable (meaningful for PE targets)
6245 single-digit power-of-two section alignment (GNU extension)
6248 If no flags are specified, the default flags depend upon the section name. If
6249 the section name is not recognized, the default will be for the section to be
6250 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
6251 from the section, rather than adding them, so if they are used on their own it
6252 will be as if no flags had been specified at all.
6254 If the optional argument to the @code{.section} directive is not quoted, it is
6255 taken as a subsection number (@pxref{Sub-Sections}).
6260 @c only print the extra heading if both COFF and ELF are set
6261 @subheading ELF Version
6264 @cindex Section Stack
6265 This is one of the ELF section stack manipulation directives. The others are
6266 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
6267 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
6268 @code{.previous} (@pxref{Previous}).
6270 @cindex @code{section} directive (ELF version)
6271 For ELF targets, the @code{.section} directive is used like this:
6274 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]]
6277 @anchor{Section Name Substitutions}
6278 @kindex --sectname-subst
6279 @cindex section name substitution
6280 If the @samp{--sectname-subst} command-line option is provided, the @var{name}
6281 argument may contain a substitution sequence. Only @code{%S} is supported
6282 at the moment, and substitutes the current section name. For example:
6285 .macro exception_code
6286 .section %S.exception
6287 [exception code here]
6302 The two @code{exception_code} invocations above would create the
6303 @code{.text.exception} and @code{.init.exception} sections respectively.
6304 This is useful e.g. to discriminate between anciliary sections that are
6305 tied to setup code to be discarded after use from anciliary sections that
6306 need to stay resident without having to define multiple @code{exception_code}
6307 macros just for that purpose.
6309 The optional @var{flags} argument is a quoted string which may contain any
6310 combination of the following characters:
6313 section is allocatable
6315 section is excluded from executable and shared library.
6319 section is executable
6321 section is mergeable
6323 section contains zero terminated strings
6325 section is a member of a section group
6327 section is used for thread-local-storage
6329 section is a member of the previously-current section's group, if any
6332 The optional @var{type} argument may contain one of the following constants:
6335 section contains data
6337 section does not contain data (i.e., section only occupies space)
6339 section contains data which is used by things other than the program
6341 section contains an array of pointers to init functions
6343 section contains an array of pointers to finish functions
6344 @item @@preinit_array
6345 section contains an array of pointers to pre-init functions
6348 Many targets only support the first three section types.
6350 Note on targets where the @code{@@} character is the start of a comment (eg
6351 ARM) then another character is used instead. For example the ARM port uses the
6354 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
6355 be specified as well as an extra argument---@var{entsize}---like this:
6358 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
6361 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
6362 constants, each @var{entsize} octets long. Sections with both @code{M} and
6363 @code{S} must contain zero terminated strings where each character is
6364 @var{entsize} bytes long. The linker may remove duplicates within sections with
6365 the same name, same entity size and same flags. @var{entsize} must be an
6366 absolute expression. For sections with both @code{M} and @code{S}, a string
6367 which is a suffix of a larger string is considered a duplicate. Thus
6368 @code{"def"} will be merged with @code{"abcdef"}; A reference to the first
6369 @code{"def"} will be changed to a reference to @code{"abcdef"+3}.
6371 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
6372 be present along with an additional field like this:
6375 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
6378 The @var{GroupName} field specifies the name of the section group to which this
6379 particular section belongs. The optional linkage field can contain:
6382 indicates that only one copy of this section should be retained
6387 Note: if both the @var{M} and @var{G} flags are present then the fields for
6388 the Merge flag should come first, like this:
6391 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
6394 If @var{flags} contains the @code{?} symbol then it may not also contain the
6395 @code{G} symbol and the @var{GroupName} or @var{linkage} fields should not be
6396 present. Instead, @code{?} says to consider the section that's current before
6397 this directive. If that section used @code{G}, then the new section will use
6398 @code{G} with those same @var{GroupName} and @var{linkage} fields implicitly.
6399 If not, then the @code{?} symbol has no effect.
6401 If no flags are specified, the default flags depend upon the section name. If
6402 the section name is not recognized, the default will be for the section to have
6403 none of the above flags: it will not be allocated in memory, nor writable, nor
6404 executable. The section will contain data.
6406 For ELF targets, the assembler supports another type of @code{.section}
6407 directive for compatibility with the Solaris assembler:
6410 .section "@var{name}"[, @var{flags}...]
6413 Note that the section name is quoted. There may be a sequence of comma
6417 section is allocatable
6421 section is executable
6423 section is excluded from executable and shared library.
6425 section is used for thread local storage
6428 This directive replaces the current section and subsection. See the
6429 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
6430 some examples of how this directive and the other section stack directives
6436 @section @code{.set @var{symbol}, @var{expression}}
6438 @cindex @code{set} directive
6439 @cindex symbol value, setting
6440 Set the value of @var{symbol} to @var{expression}. This
6441 changes @var{symbol}'s value and type to conform to
6442 @var{expression}. If @var{symbol} was flagged as external, it remains
6443 flagged (@pxref{Symbol Attributes}).
6445 You may @code{.set} a symbol many times in the same assembly provided that the
6446 values given to the symbol are constants. Values that are based on expressions
6447 involving other symbols are allowed, but some targets may restrict this to only
6448 being done once per assembly. This is because those targets do not set the
6449 addresses of symbols at assembly time, but rather delay the assignment until a
6450 final link is performed. This allows the linker a chance to change the code in
6451 the files, changing the location of, and the relative distance between, various
6454 If you @code{.set} a global symbol, the value stored in the object
6455 file is the last value stored into it.
6458 On Z80 @code{set} is a real instruction, use
6459 @samp{@var{symbol} defl @var{expression}} instead.
6463 @section @code{.short @var{expressions}}
6465 @cindex @code{short} directive
6467 @code{.short} is normally the same as @samp{.word}.
6468 @xref{Word,,@code{.word}}.
6470 In some configurations, however, @code{.short} and @code{.word} generate
6471 numbers of different lengths. @xref{Machine Dependencies}.
6475 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
6478 This expects zero or more @var{expressions}, and emits
6479 a 16 bit number for each.
6484 @section @code{.single @var{flonums}}
6486 @cindex @code{single} directive
6487 @cindex floating point numbers (single)
6488 This directive assembles zero or more flonums, separated by commas. It
6489 has the same effect as @code{.float}.
6491 The exact kind of floating point numbers emitted depends on how
6492 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
6496 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
6497 numbers in @sc{ieee} format.
6503 @section @code{.size}
6505 This directive is used to set the size associated with a symbol.
6509 @c only print the extra heading if both COFF and ELF are set
6510 @subheading COFF Version
6513 @cindex @code{size} directive (COFF version)
6514 For COFF targets, the @code{.size} directive is only permitted inside
6515 @code{.def}/@code{.endef} pairs. It is used like this:
6518 .size @var{expression}
6522 @samp{.size} is only meaningful when generating COFF format output; when
6523 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6530 @c only print the extra heading if both COFF and ELF are set
6531 @subheading ELF Version
6534 @cindex @code{size} directive (ELF version)
6535 For ELF targets, the @code{.size} directive is used like this:
6538 .size @var{name} , @var{expression}
6541 This directive sets the size associated with a symbol @var{name}.
6542 The size in bytes is computed from @var{expression} which can make use of label
6543 arithmetic. This directive is typically used to set the size of function
6548 @ifclear no-space-dir
6550 @section @code{.skip @var{size} , @var{fill}}
6552 @cindex @code{skip} directive
6553 @cindex filling memory
6554 This directive emits @var{size} bytes, each of value @var{fill}. Both
6555 @var{size} and @var{fill} are absolute expressions. If the comma and
6556 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
6561 @section @code{.sleb128 @var{expressions}}
6563 @cindex @code{sleb128} directive
6564 @var{sleb128} stands for ``signed little endian base 128.'' This is a
6565 compact, variable length representation of numbers used by the DWARF
6566 symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}.
6568 @ifclear no-space-dir
6570 @section @code{.space @var{size} , @var{fill}}
6572 @cindex @code{space} directive
6573 @cindex filling memory
6574 This directive emits @var{size} bytes, each of value @var{fill}. Both
6575 @var{size} and @var{fill} are absolute expressions. If the comma
6576 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
6581 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
6582 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
6583 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
6584 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
6592 @section @code{.stabd, .stabn, .stabs}
6594 @cindex symbolic debuggers, information for
6595 @cindex @code{stab@var{x}} directives
6596 There are three directives that begin @samp{.stab}.
6597 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
6598 The symbols are not entered in the @command{@value{AS}} hash table: they
6599 cannot be referenced elsewhere in the source file.
6600 Up to five fields are required:
6604 This is the symbol's name. It may contain any character except
6605 @samp{\000}, so is more general than ordinary symbol names. Some
6606 debuggers used to code arbitrarily complex structures into symbol names
6610 An absolute expression. The symbol's type is set to the low 8 bits of
6611 this expression. Any bit pattern is permitted, but @code{@value{LD}}
6612 and debuggers choke on silly bit patterns.
6615 An absolute expression. The symbol's ``other'' attribute is set to the
6616 low 8 bits of this expression.
6619 An absolute expression. The symbol's descriptor is set to the low 16
6620 bits of this expression.
6623 An absolute expression which becomes the symbol's value.
6626 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
6627 or @code{.stabs} statement, the symbol has probably already been created;
6628 you get a half-formed symbol in your object file. This is
6629 compatible with earlier assemblers!
6632 @cindex @code{stabd} directive
6633 @item .stabd @var{type} , @var{other} , @var{desc}
6635 The ``name'' of the symbol generated is not even an empty string.
6636 It is a null pointer, for compatibility. Older assemblers used a
6637 null pointer so they didn't waste space in object files with empty
6640 The symbol's value is set to the location counter,
6641 relocatably. When your program is linked, the value of this symbol
6642 is the address of the location counter when the @code{.stabd} was
6645 @cindex @code{stabn} directive
6646 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
6647 The name of the symbol is set to the empty string @code{""}.
6649 @cindex @code{stabs} directive
6650 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
6651 All five fields are specified.
6657 @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
6658 "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
6660 @cindex string, copying to object file
6661 @cindex string8, copying to object file
6662 @cindex string16, copying to object file
6663 @cindex string32, copying to object file
6664 @cindex string64, copying to object file
6665 @cindex @code{string} directive
6666 @cindex @code{string8} directive
6667 @cindex @code{string16} directive
6668 @cindex @code{string32} directive
6669 @cindex @code{string64} directive
6671 Copy the characters in @var{str} to the object file. You may specify more than
6672 one string to copy, separated by commas. Unless otherwise specified for a
6673 particular machine, the assembler marks the end of each string with a 0 byte.
6674 You can use any of the escape sequences described in @ref{Strings,,Strings}.
6676 The variants @code{string16}, @code{string32} and @code{string64} differ from
6677 the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
6678 copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
6679 are stored in target endianness byte order.
6685 .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
6686 .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
6691 @section @code{.struct @var{expression}}
6693 @cindex @code{struct} directive
6694 Switch to the absolute section, and set the section offset to @var{expression},
6695 which must be an absolute expression. You might use this as follows:
6704 This would define the symbol @code{field1} to have the value 0, the symbol
6705 @code{field2} to have the value 4, and the symbol @code{field3} to have the
6706 value 8. Assembly would be left in the absolute section, and you would need to
6707 use a @code{.section} directive of some sort to change to some other section
6708 before further assembly.
6712 @section @code{.subsection @var{name}}
6714 @cindex @code{subsection} directive
6715 @cindex Section Stack
6716 This is one of the ELF section stack manipulation directives. The others are
6717 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
6718 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6721 This directive replaces the current subsection with @code{name}. The current
6722 section is not changed. The replaced subsection is put onto the section stack
6723 in place of the then current top of stack subsection.
6728 @section @code{.symver}
6729 @cindex @code{symver} directive
6730 @cindex symbol versioning
6731 @cindex versions of symbols
6732 Use the @code{.symver} directive to bind symbols to specific version nodes
6733 within a source file. This is only supported on ELF platforms, and is
6734 typically used when assembling files to be linked into a shared library.
6735 There are cases where it may make sense to use this in objects to be bound
6736 into an application itself so as to override a versioned symbol from a
6739 For ELF targets, the @code{.symver} directive can be used like this:
6741 .symver @var{name}, @var{name2@@nodename}
6743 If the symbol @var{name} is defined within the file
6744 being assembled, the @code{.symver} directive effectively creates a symbol
6745 alias with the name @var{name2@@nodename}, and in fact the main reason that we
6746 just don't try and create a regular alias is that the @var{@@} character isn't
6747 permitted in symbol names. The @var{name2} part of the name is the actual name
6748 of the symbol by which it will be externally referenced. The name @var{name}
6749 itself is merely a name of convenience that is used so that it is possible to
6750 have definitions for multiple versions of a function within a single source
6751 file, and so that the compiler can unambiguously know which version of a
6752 function is being mentioned. The @var{nodename} portion of the alias should be
6753 the name of a node specified in the version script supplied to the linker when
6754 building a shared library. If you are attempting to override a versioned
6755 symbol from a shared library, then @var{nodename} should correspond to the
6756 nodename of the symbol you are trying to override.
6758 If the symbol @var{name} is not defined within the file being assembled, all
6759 references to @var{name} will be changed to @var{name2@@nodename}. If no
6760 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
6763 Another usage of the @code{.symver} directive is:
6765 .symver @var{name}, @var{name2@@@@nodename}
6767 In this case, the symbol @var{name} must exist and be defined within
6768 the file being assembled. It is similar to @var{name2@@nodename}. The
6769 difference is @var{name2@@@@nodename} will also be used to resolve
6770 references to @var{name2} by the linker.
6772 The third usage of the @code{.symver} directive is:
6774 .symver @var{name}, @var{name2@@@@@@nodename}
6776 When @var{name} is not defined within the
6777 file being assembled, it is treated as @var{name2@@nodename}. When
6778 @var{name} is defined within the file being assembled, the symbol
6779 name, @var{name}, will be changed to @var{name2@@@@nodename}.
6784 @section @code{.tag @var{structname}}
6786 @cindex COFF structure debugging
6787 @cindex structure debugging, COFF
6788 @cindex @code{tag} directive
6789 This directive is generated by compilers to include auxiliary debugging
6790 information in the symbol table. It is only permitted inside
6791 @code{.def}/@code{.endef} pairs. Tags are used to link structure
6792 definitions in the symbol table with instances of those structures.
6795 @samp{.tag} is only used when generating COFF format output; when
6796 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6802 @section @code{.text @var{subsection}}
6804 @cindex @code{text} directive
6805 Tells @command{@value{AS}} to assemble the following statements onto the end of
6806 the text subsection numbered @var{subsection}, which is an absolute
6807 expression. If @var{subsection} is omitted, subsection number zero
6811 @section @code{.title "@var{heading}"}
6813 @cindex @code{title} directive
6814 @cindex listing control: title line
6815 Use @var{heading} as the title (second line, immediately after the
6816 source file name and pagenumber) when generating assembly listings.
6818 This directive affects subsequent pages, as well as the current page if
6819 it appears within ten lines of the top of a page.
6823 @section @code{.type}
6825 This directive is used to set the type of a symbol.
6829 @c only print the extra heading if both COFF and ELF are set
6830 @subheading COFF Version
6833 @cindex COFF symbol type
6834 @cindex symbol type, COFF
6835 @cindex @code{type} directive (COFF version)
6836 For COFF targets, this directive is permitted only within
6837 @code{.def}/@code{.endef} pairs. It is used like this:
6843 This records the integer @var{int} as the type attribute of a symbol table
6847 @samp{.type} is associated only with COFF format output; when
6848 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
6849 directive but ignores it.
6855 @c only print the extra heading if both COFF and ELF are set
6856 @subheading ELF Version
6859 @cindex ELF symbol type
6860 @cindex symbol type, ELF
6861 @cindex @code{type} directive (ELF version)
6862 For ELF targets, the @code{.type} directive is used like this:
6865 .type @var{name} , @var{type description}
6868 This sets the type of symbol @var{name} to be either a
6869 function symbol or an object symbol. There are five different syntaxes
6870 supported for the @var{type description} field, in order to provide
6871 compatibility with various other assemblers.
6873 Because some of the characters used in these syntaxes (such as @samp{@@} and
6874 @samp{#}) are comment characters for some architectures, some of the syntaxes
6875 below do not work on all architectures. The first variant will be accepted by
6876 the GNU assembler on all architectures so that variant should be used for
6877 maximum portability, if you do not need to assemble your code with other
6880 The syntaxes supported are:
6883 .type <name> STT_<TYPE_IN_UPPER_CASE>
6884 .type <name>,#<type>
6885 .type <name>,@@<type>
6886 .type <name>,%<type>
6887 .type <name>,"<type>"
6890 The types supported are:
6895 Mark the symbol as being a function name.
6898 @itemx gnu_indirect_function
6899 Mark the symbol as an indirect function when evaluated during reloc
6900 processing. (This is only supported on assemblers targeting GNU systems).
6904 Mark the symbol as being a data object.
6908 Mark the symbol as being a thead-local data object.
6912 Mark the symbol as being a common data object.
6916 Does not mark the symbol in any way. It is supported just for completeness.
6918 @item gnu_unique_object
6919 Marks the symbol as being a globally unique data object. The dynamic linker
6920 will make sure that in the entire process there is just one symbol with this
6921 name and type in use. (This is only supported on assemblers targeting GNU
6926 Note: Some targets support extra types in addition to those listed above.
6932 @section @code{.uleb128 @var{expressions}}
6934 @cindex @code{uleb128} directive
6935 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
6936 compact, variable length representation of numbers used by the DWARF
6937 symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}.
6941 @section @code{.val @var{addr}}
6943 @cindex @code{val} directive
6944 @cindex COFF value attribute
6945 @cindex value attribute, COFF
6946 This directive, permitted only within @code{.def}/@code{.endef} pairs,
6947 records the address @var{addr} as the value attribute of a symbol table
6951 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
6952 configured for @code{b.out}, it accepts this directive but ignores it.
6958 @section @code{.version "@var{string}"}
6960 @cindex @code{version} directive
6961 This directive creates a @code{.note} section and places into it an ELF
6962 formatted note of type NT_VERSION. The note's name is set to @code{string}.
6967 @section @code{.vtable_entry @var{table}, @var{offset}}
6969 @cindex @code{vtable_entry} directive
6970 This directive finds or creates a symbol @code{table} and creates a
6971 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
6974 @section @code{.vtable_inherit @var{child}, @var{parent}}
6976 @cindex @code{vtable_inherit} directive
6977 This directive finds the symbol @code{child} and finds or creates the symbol
6978 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
6979 parent whose addend is the value of the child symbol. As a special case the
6980 parent name of @code{0} is treated as referring to the @code{*ABS*} section.
6984 @section @code{.warning "@var{string}"}
6985 @cindex warning directive
6986 Similar to the directive @code{.error}
6987 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
6990 @section @code{.weak @var{names}}
6992 @cindex @code{weak} directive
6993 This 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 COFF targets other than PE, weak symbols are a GNU extension. This
6997 directive sets the weak attribute on the comma separated list of symbol
6998 @code{names}. If the symbols do not already exist, they will be created.
7000 On the PE target, weak symbols are supported natively as weak aliases.
7001 When a weak symbol is created that is not an alias, GAS creates an
7002 alternate symbol to hold the default value.
7005 @section @code{.weakref @var{alias}, @var{target}}
7007 @cindex @code{weakref} directive
7008 This directive creates an alias to the target symbol that enables the symbol to
7009 be referenced with weak-symbol semantics, but without actually making it weak.
7010 If direct references or definitions of the symbol are present, then the symbol
7011 will not be weak, but if all references to it are through weak references, the
7012 symbol will be marked as weak in the symbol table.
7014 The effect is equivalent to moving all references to the alias to a separate
7015 assembly source file, renaming the alias to the symbol in it, declaring the
7016 symbol as weak there, and running a reloadable link to merge the object files
7017 resulting from the assembly of the new source file and the old source file that
7018 had the references to the alias removed.
7020 The alias itself never makes to the symbol table, and is entirely handled
7021 within the assembler.
7024 @section @code{.word @var{expressions}}
7026 @cindex @code{word} directive
7027 This directive expects zero or more @var{expressions}, of any section,
7028 separated by commas.
7031 For each expression, @command{@value{AS}} emits a 32-bit number.
7034 For each expression, @command{@value{AS}} emits a 16-bit number.
7039 The size of the number emitted, and its byte order,
7040 depend on what target computer the assembly is for.
7043 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
7044 @c happen---32-bit addressability, period; no long/short jumps.
7045 @ifset DIFF-TBL-KLUGE
7046 @cindex difference tables altered
7047 @cindex altered difference tables
7049 @emph{Warning: Special Treatment to support Compilers}
7053 Machines with a 32-bit address space, but that do less than 32-bit
7054 addressing, require the following special treatment. If the machine of
7055 interest to you does 32-bit addressing (or doesn't require it;
7056 @pxref{Machine Dependencies}), you can ignore this issue.
7059 In order to assemble compiler output into something that works,
7060 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
7061 Directives of the form @samp{.word sym1-sym2} are often emitted by
7062 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
7063 directive of the form @samp{.word sym1-sym2}, and the difference between
7064 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
7065 creates a @dfn{secondary jump table}, immediately before the next label.
7066 This secondary jump table is preceded by a short-jump to the
7067 first byte after the secondary table. This short-jump prevents the flow
7068 of control from accidentally falling into the new table. Inside the
7069 table is a long-jump to @code{sym2}. The original @samp{.word}
7070 contains @code{sym1} minus the address of the long-jump to
7073 If there were several occurrences of @samp{.word sym1-sym2} before the
7074 secondary jump table, all of them are adjusted. If there was a
7075 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
7076 long-jump to @code{sym4} is included in the secondary jump table,
7077 and the @code{.word} directives are adjusted to contain @code{sym3}
7078 minus the address of the long-jump to @code{sym4}; and so on, for as many
7079 entries in the original jump table as necessary.
7082 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
7083 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
7084 assembly language programmers.
7087 @c end DIFF-TBL-KLUGE
7089 @ifclear no-space-dir
7091 @section @code{.zero @var{size}}
7093 @cindex @code{zero} directive
7094 @cindex filling memory with zero bytes
7095 This directive emits @var{size} 0-valued bytes. @var{size} must be an absolute
7096 expression. This directive is actually an alias for the @samp{.skip} directive
7097 so in can take an optional second argument of the value to store in the bytes
7098 instead of zero. Using @samp{.zero} in this way would be confusing however.
7102 @section Deprecated Directives
7104 @cindex deprecated directives
7105 @cindex obsolescent directives
7106 One day these directives won't work.
7107 They are included for compatibility with older assemblers.
7114 @node Object Attributes
7115 @chapter Object Attributes
7116 @cindex object attributes
7118 @command{@value{AS}} assembles source files written for a specific architecture
7119 into object files for that architecture. But not all object files are alike.
7120 Many architectures support incompatible variations. For instance, floating
7121 point arguments might be passed in floating point registers if the object file
7122 requires hardware floating point support---or floating point arguments might be
7123 passed in integer registers if the object file supports processors with no
7124 hardware floating point unit. Or, if two objects are built for different
7125 generations of the same architecture, the combination may require the
7126 newer generation at run-time.
7128 This information is useful during and after linking. At link time,
7129 @command{@value{LD}} can warn about incompatible object files. After link
7130 time, tools like @command{gdb} can use it to process the linked file
7133 Compatibility information is recorded as a series of object attributes. Each
7134 attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
7135 string, and indicates who sets the meaning of the tag. The tag is an integer,
7136 and indicates what property the attribute describes. The value may be a string
7137 or an integer, and indicates how the property affects this object. Missing
7138 attributes are the same as attributes with a zero value or empty string value.
7140 Object attributes were developed as part of the ABI for the ARM Architecture.
7141 The file format is documented in @cite{ELF for the ARM Architecture}.
7144 * GNU Object Attributes:: @sc{gnu} Object Attributes
7145 * Defining New Object Attributes:: Defining New Object Attributes
7148 @node GNU Object Attributes
7149 @section @sc{gnu} Object Attributes
7151 The @code{.gnu_attribute} directive records an object attribute
7152 with vendor @samp{gnu}.
7154 Except for @samp{Tag_compatibility}, which has both an integer and a string for
7155 its value, @sc{gnu} attributes have a string value if the tag number is odd and
7156 an integer value if the tag number is even. The second bit (@code{@var{tag} &
7157 2} is set for architecture-independent attributes and clear for
7158 architecture-dependent ones.
7160 @subsection Common @sc{gnu} attributes
7162 These attributes are valid on all architectures.
7165 @item Tag_compatibility (32)
7166 The compatibility attribute takes an integer flag value and a vendor name. If
7167 the flag value is 0, the file is compatible with other toolchains. If it is 1,
7168 then the file is only compatible with the named toolchain. If it is greater
7169 than 1, the file can only be processed by other toolchains under some private
7170 arrangement indicated by the flag value and the vendor name.
7173 @subsection MIPS Attributes
7176 @item Tag_GNU_MIPS_ABI_FP (4)
7177 The floating-point ABI used by this object file. The value will be:
7181 0 for files not affected by the floating-point ABI.
7183 1 for files using the hardware floating-point ABI with a standard
7184 double-precision FPU.
7186 2 for files using the hardware floating-point ABI with a single-precision FPU.
7188 3 for files using the software floating-point ABI.
7190 4 for files using the deprecated hardware floating-point ABI which used 64-bit
7191 floating-point registers, 32-bit general-purpose registers and increased the
7192 number of callee-saved floating-point registers.
7194 5 for files using the hardware floating-point ABI with a double-precision FPU
7195 with either 32-bit or 64-bit floating-point registers and 32-bit
7196 general-purpose registers.
7198 6 for files using the hardware floating-point ABI with 64-bit floating-point
7199 registers and 32-bit general-purpose registers.
7201 7 for files using the hardware floating-point ABI with 64-bit floating-point
7202 registers, 32-bit general-purpose registers and a rule that forbids the
7203 direct use of odd-numbered single-precision floating-point registers.
7207 @subsection PowerPC Attributes
7210 @item Tag_GNU_Power_ABI_FP (4)
7211 The floating-point ABI used by this object file. The value will be:
7215 0 for files not affected by the floating-point ABI.
7217 1 for files using double-precision hardware floating-point ABI.
7219 2 for files using the software floating-point ABI.
7221 3 for files using single-precision hardware floating-point ABI.
7224 @item Tag_GNU_Power_ABI_Vector (8)
7225 The vector ABI used by this object file. The value will be:
7229 0 for files not affected by the vector ABI.
7231 1 for files using general purpose registers to pass vectors.
7233 2 for files using AltiVec registers to pass vectors.
7235 3 for files using SPE registers to pass vectors.
7239 @subsection IBM z Systems Attributes
7242 @item Tag_GNU_S390_ABI_Vector (8)
7243 The vector ABI used by this object file. The value will be:
7247 0 for files not affected by the vector ABI.
7249 1 for files using software vector ABI.
7251 2 for files using hardware vector ABI.
7255 @node Defining New Object Attributes
7256 @section Defining New Object Attributes
7258 If you want to define a new @sc{gnu} object attribute, here are the places you
7259 will need to modify. New attributes should be discussed on the @samp{binutils}
7264 This manual, which is the official register of attributes.
7266 The header for your architecture @file{include/elf}, to define the tag.
7268 The @file{bfd} support file for your architecture, to merge the attribute
7269 and issue any appropriate link warnings.
7271 Test cases in @file{ld/testsuite} for merging and link warnings.
7273 @file{binutils/readelf.c} to display your attribute.
7275 GCC, if you want the compiler to mark the attribute automatically.
7281 @node Machine Dependencies
7282 @chapter Machine Dependent Features
7284 @cindex machine dependencies
7285 The machine instruction sets are (almost by definition) different on
7286 each machine where @command{@value{AS}} runs. Floating point representations
7287 vary as well, and @command{@value{AS}} often supports a few additional
7288 directives or command-line options for compatibility with other
7289 assemblers on a particular platform. Finally, some versions of
7290 @command{@value{AS}} support special pseudo-instructions for branch
7293 This chapter discusses most of these differences, though it does not
7294 include details on any machine's instruction set. For details on that
7295 subject, see the hardware manufacturer's manual.
7299 * AArch64-Dependent:: AArch64 Dependent Features
7302 * Alpha-Dependent:: Alpha Dependent Features
7305 * ARC-Dependent:: ARC Dependent Features
7308 * ARM-Dependent:: ARM Dependent Features
7311 * AVR-Dependent:: AVR Dependent Features
7314 * Blackfin-Dependent:: Blackfin Dependent Features
7317 * CR16-Dependent:: CR16 Dependent Features
7320 * CRIS-Dependent:: CRIS Dependent Features
7323 * D10V-Dependent:: D10V Dependent Features
7326 * D30V-Dependent:: D30V Dependent Features
7329 * Epiphany-Dependent:: EPIPHANY Dependent Features
7332 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7335 * HPPA-Dependent:: HPPA Dependent Features
7338 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
7341 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
7344 * i860-Dependent:: Intel 80860 Dependent Features
7347 * i960-Dependent:: Intel 80960 Dependent Features
7350 * IA-64-Dependent:: Intel IA-64 Dependent Features
7353 * IP2K-Dependent:: IP2K Dependent Features
7356 * LM32-Dependent:: LM32 Dependent Features
7359 * M32C-Dependent:: M32C Dependent Features
7362 * M32R-Dependent:: M32R Dependent Features
7365 * M68K-Dependent:: M680x0 Dependent Features
7368 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
7371 * Meta-Dependent :: Meta Dependent Features
7374 * MicroBlaze-Dependent:: MICROBLAZE Dependent Features
7377 * MIPS-Dependent:: MIPS Dependent Features
7380 * MMIX-Dependent:: MMIX Dependent Features
7383 * MSP430-Dependent:: MSP430 Dependent Features
7386 * NDS32-Dependent:: Andes NDS32 Dependent Features
7389 * NiosII-Dependent:: Altera Nios II Dependent Features
7392 * NS32K-Dependent:: NS32K Dependent Features
7395 * PDP-11-Dependent:: PDP-11 Dependent Features
7398 * PJ-Dependent:: picoJava Dependent Features
7401 * PPC-Dependent:: PowerPC Dependent Features
7404 * RL78-Dependent:: RL78 Dependent Features
7407 * RX-Dependent:: RX Dependent Features
7410 * S/390-Dependent:: IBM S/390 Dependent Features
7413 * SCORE-Dependent:: SCORE Dependent Features
7416 * SH-Dependent:: Renesas / SuperH SH Dependent Features
7417 * SH64-Dependent:: SuperH SH64 Dependent Features
7420 * Sparc-Dependent:: SPARC Dependent Features
7423 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
7426 * TIC6X-Dependent :: TI TMS320C6x Dependent Features
7429 * TILE-Gx-Dependent :: Tilera TILE-Gx Dependent Features
7432 * TILEPro-Dependent :: Tilera TILEPro Dependent Features
7435 * V850-Dependent:: V850 Dependent Features
7438 * Vax-Dependent:: VAX Dependent Features
7441 * Visium-Dependent:: Visium Dependent Features
7444 * XGATE-Dependent:: XGATE Features
7447 * XSTORMY16-Dependent:: XStormy16 Dependent Features
7450 * Xtensa-Dependent:: Xtensa Dependent Features
7453 * Z80-Dependent:: Z80 Dependent Features
7456 * Z8000-Dependent:: Z8000 Dependent Features
7463 @c The following major nodes are *sections* in the GENERIC version, *chapters*
7464 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
7465 @c peculiarity: to preserve cross-references, there must be a node called
7466 @c "Machine Dependencies". Hence the conditional nodenames in each
7467 @c major node below. Node defaulting in makeinfo requires adjacency of
7468 @c node and sectioning commands; hence the repetition of @chapter BLAH
7469 @c in both conditional blocks.
7472 @include c-aarch64.texi
7476 @include c-alpha.texi
7492 @include c-bfin.texi
7496 @include c-cr16.texi
7500 @include c-cris.texi
7505 @node Machine Dependencies
7506 @chapter Machine Dependent Features
7508 The machine instruction sets are different on each Renesas chip family,
7509 and there are also some syntax differences among the families. This
7510 chapter describes the specific @command{@value{AS}} features for each
7514 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7515 * SH-Dependent:: Renesas SH Dependent Features
7522 @include c-d10v.texi
7526 @include c-d30v.texi
7530 @include c-epiphany.texi
7534 @include c-h8300.texi
7538 @include c-hppa.texi
7542 @include c-i370.texi
7546 @include c-i386.texi
7550 @include c-i860.texi
7554 @include c-i960.texi
7558 @include c-ia64.texi
7562 @include c-ip2k.texi
7566 @include c-lm32.texi
7570 @include c-m32c.texi
7574 @include c-m32r.texi
7578 @include c-m68k.texi
7582 @include c-m68hc11.texi
7586 @include c-metag.texi
7590 @include c-microblaze.texi
7594 @include c-mips.texi
7598 @include c-mmix.texi
7602 @include c-msp430.texi
7606 @include c-nds32.texi
7610 @include c-nios2.texi
7614 @include c-ns32k.texi
7618 @include c-pdp11.texi
7630 @include c-rl78.texi
7638 @include c-s390.texi
7642 @include c-score.texi
7647 @include c-sh64.texi
7651 @include c-sparc.texi
7655 @include c-tic54x.texi
7659 @include c-tic6x.texi
7663 @include c-tilegx.texi
7667 @include c-tilepro.texi
7671 @include c-v850.texi
7679 @include c-visium.texi
7683 @include c-xgate.texi
7687 @include c-xstormy16.texi
7691 @include c-xtensa.texi
7703 @c reverse effect of @down at top of generic Machine-Dep chapter
7707 @node Reporting Bugs
7708 @chapter Reporting Bugs
7709 @cindex bugs in assembler
7710 @cindex reporting bugs in assembler
7712 Your bug reports play an essential role in making @command{@value{AS}} reliable.
7714 Reporting a bug may help you by bringing a solution to your problem, or it may
7715 not. But in any case the principal function of a bug report is to help the
7716 entire community by making the next version of @command{@value{AS}} work better.
7717 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
7719 In order for a bug report to serve its purpose, you must include the
7720 information that enables us to fix the bug.
7723 * Bug Criteria:: Have you found a bug?
7724 * Bug Reporting:: How to report bugs
7728 @section Have You Found a Bug?
7729 @cindex bug criteria
7731 If you are not sure whether you have found a bug, here are some guidelines:
7734 @cindex fatal signal
7735 @cindex assembler crash
7736 @cindex crash of assembler
7738 If the assembler gets a fatal signal, for any input whatever, that is a
7739 @command{@value{AS}} bug. Reliable assemblers never crash.
7741 @cindex error on valid input
7743 If @command{@value{AS}} produces an error message for valid input, that is a bug.
7745 @cindex invalid input
7747 If @command{@value{AS}} does not produce an error message for invalid input, that
7748 is a bug. However, you should note that your idea of ``invalid input'' might
7749 be our idea of ``an extension'' or ``support for traditional practice''.
7752 If you are an experienced user of assemblers, your suggestions for improvement
7753 of @command{@value{AS}} are welcome in any case.
7757 @section How to Report Bugs
7759 @cindex assembler bugs, reporting
7761 A number of companies and individuals offer support for @sc{gnu} products. If
7762 you obtained @command{@value{AS}} from a support organization, we recommend you
7763 contact that organization first.
7765 You can find contact information for many support companies and
7766 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
7770 In any event, we also recommend that you send bug reports for @command{@value{AS}}
7774 The fundamental principle of reporting bugs usefully is this:
7775 @strong{report all the facts}. If you are not sure whether to state a
7776 fact or leave it out, state it!
7778 Often people omit facts because they think they know what causes the problem
7779 and assume that some details do not matter. Thus, you might assume that the
7780 name of a symbol you use in an example does not matter. Well, probably it does
7781 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
7782 happens to fetch from the location where that name is stored in memory;
7783 perhaps, if the name were different, the contents of that location would fool
7784 the assembler into doing the right thing despite the bug. Play it safe and
7785 give a specific, complete example. That is the easiest thing for you to do,
7786 and the most helpful.
7788 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
7789 it is new to us. Therefore, always write your bug reports on the assumption
7790 that the bug has not been reported previously.
7792 Sometimes people give a few sketchy facts and ask, ``Does this ring a
7793 bell?'' This cannot help us fix a bug, so it is basically useless. We
7794 respond by asking for enough details to enable us to investigate.
7795 You might as well expedite matters by sending them to begin with.
7797 To enable us to fix the bug, you should include all these things:
7801 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
7802 it with the @samp{--version} argument.
7804 Without this, we will not know whether there is any point in looking for
7805 the bug in the current version of @command{@value{AS}}.
7808 Any patches you may have applied to the @command{@value{AS}} source.
7811 The type of machine you are using, and the operating system name and
7815 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
7819 The command arguments you gave the assembler to assemble your example and
7820 observe the bug. To guarantee you will not omit something important, list them
7821 all. A copy of the Makefile (or the output from make) is sufficient.
7823 If we were to try to guess the arguments, we would probably guess wrong
7824 and then we might not encounter the bug.
7827 A complete input file that will reproduce the bug. If the bug is observed when
7828 the assembler is invoked via a compiler, send the assembler source, not the
7829 high level language source. Most compilers will produce the assembler source
7830 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
7831 the options @samp{-v --save-temps}; this will save the assembler source in a
7832 file with an extension of @file{.s}, and also show you exactly how
7833 @command{@value{AS}} is being run.
7836 A description of what behavior you observe that you believe is
7837 incorrect. For example, ``It gets a fatal signal.''
7839 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
7840 will certainly notice it. But if the bug is incorrect output, we might not
7841 notice unless it is glaringly wrong. You might as well not give us a chance to
7844 Even if the problem you experience is a fatal signal, you should still say so
7845 explicitly. Suppose something strange is going on, such as, your copy of
7846 @command{@value{AS}} is out of sync, or you have encountered a bug in the C
7847 library on your system. (This has happened!) Your copy might crash and ours
7848 would not. If you told us to expect a crash, then when ours fails to crash, we
7849 would know that the bug was not happening for us. If you had not told us to
7850 expect a crash, then we would not be able to draw any conclusion from our
7854 If you wish to suggest changes to the @command{@value{AS}} source, send us context
7855 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
7856 option. Always send diffs from the old file to the new file. If you even
7857 discuss something in the @command{@value{AS}} source, refer to it by context, not
7860 The line numbers in our development sources will not match those in your
7861 sources. Your line numbers would convey no useful information to us.
7864 Here are some things that are not necessary:
7868 A description of the envelope of the bug.
7870 Often people who encounter a bug spend a lot of time investigating
7871 which changes to the input file will make the bug go away and which
7872 changes will not affect it.
7874 This is often time consuming and not very useful, because the way we
7875 will find the bug is by running a single example under the debugger
7876 with breakpoints, not by pure deduction from a series of examples.
7877 We recommend that you save your time for something else.
7879 Of course, if you can find a simpler example to report @emph{instead}
7880 of the original one, that is a convenience for us. Errors in the
7881 output will be easier to spot, running under the debugger will take
7882 less time, and so on.
7884 However, simplification is not vital; if you do not want to do this,
7885 report the bug anyway and send us the entire test case you used.
7888 A patch for the bug.
7890 A patch for the bug does help us if it is a good one. But do not omit
7891 the necessary information, such as the test case, on the assumption that
7892 a patch is all we need. We might see problems with your patch and decide
7893 to fix the problem another way, or we might not understand it at all.
7895 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
7896 construct an example that will make the program follow a certain path through
7897 the code. If you do not send us the example, we will not be able to construct
7898 one, so we will not be able to verify that the bug is fixed.
7900 And if we cannot understand what bug you are trying to fix, or why your
7901 patch should be an improvement, we will not install it. A test case will
7902 help us to understand.
7905 A guess about what the bug is or what it depends on.
7907 Such guesses are usually wrong. Even we cannot guess right about such
7908 things without first using the debugger to find the facts.
7911 @node Acknowledgements
7912 @chapter Acknowledgements
7914 If you have contributed to GAS and your name isn't listed here,
7915 it is not meant as a slight. We just don't know about it. Send mail to the
7916 maintainer, and we'll correct the situation. Currently
7918 the maintainer is Nick Clifton (email address @code{nickc@@redhat.com}).
7920 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
7923 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
7924 information and the 68k series machines, most of the preprocessing pass, and
7925 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
7927 K. Richard Pixley maintained GAS for a while, adding various enhancements and
7928 many bug fixes, including merging support for several processors, breaking GAS
7929 up to handle multiple object file format back ends (including heavy rewrite,
7930 testing, an integration of the coff and b.out back ends), adding configuration
7931 including heavy testing and verification of cross assemblers and file splits
7932 and renaming, converted GAS to strictly ANSI C including full prototypes, added
7933 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
7934 port (including considerable amounts of reverse engineering), a SPARC opcode
7935 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
7936 assertions and made them work, much other reorganization, cleanup, and lint.
7938 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
7939 in format-specific I/O modules.
7941 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
7942 has done much work with it since.
7944 The Intel 80386 machine description was written by Eliot Dresselhaus.
7946 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
7948 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
7949 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
7951 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
7952 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
7953 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
7954 support a.out format.
7956 Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
7957 tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
7958 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
7959 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
7962 John Gilmore built the AMD 29000 support, added @code{.include} support, and
7963 simplified the configuration of which versions accept which directives. He
7964 updated the 68k machine description so that Motorola's opcodes always produced
7965 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
7966 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
7967 cross-compilation support, and one bug in relaxation that took a week and
7968 required the proverbial one-bit fix.
7970 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
7971 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
7972 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
7973 PowerPC assembler, and made a few other minor patches.
7975 Steve Chamberlain made GAS able to generate listings.
7977 Hewlett-Packard contributed support for the HP9000/300.
7979 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
7980 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
7981 formats). This work was supported by both the Center for Software Science at
7982 the University of Utah and Cygnus Support.
7984 Support for ELF format files has been worked on by Mark Eichin of Cygnus
7985 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
7986 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
7987 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
7988 and some initial 64-bit support).
7990 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
7992 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
7993 support for openVMS/Alpha.
7995 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
7998 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
7999 Inc.@: added support for Xtensa processors.
8001 Several engineers at Cygnus Support have also provided many small bug fixes and
8002 configuration enhancements.
8004 Jon Beniston added support for the Lattice Mico32 architecture.
8006 Many others have contributed large or small bugfixes and enhancements. If
8007 you have contributed significant work and are not mentioned on this list, and
8008 want to be, let us know. Some of the history has been lost; we are not
8009 intentionally leaving anyone out.
8011 @node GNU Free Documentation License
8012 @appendix GNU Free Documentation License
8016 @unnumbered AS Index
projects / deliverable / binutils-gdb.git / blob