1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright (C) 1991-2015 Free Software Foundation, Inc.
3 @c UPDATE!! On future updates--
4 @c (1) check for new machine-dep cmdline options in
5 @c md_parse_option definitions in config/tc-*.c
6 @c (2) for platform-specific directives, examine md_pseudo_op
8 @c (3) for object-format specific directives, examine obj_pseudo_op
10 @c (4) portable directives in potable[] in read.c
14 @macro gcctabopt{body}
17 @c defaults, config file may override:
22 @include asconfig.texi
27 @c common OR combinations of conditions
53 @set abnormal-separator
57 @settitle Using @value{AS}
60 @settitle Using @value{AS} (@value{TARGET})
62 @setchapternewpage odd
67 @c WARE! Some of the machine-dependent sections contain tables of machine
68 @c instructions. Except in multi-column format, these tables look silly.
69 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
70 @c the multi-col format is faked within @example sections.
72 @c Again unfortunately, the natural size that fits on a page, for these tables,
73 @c is different depending on whether or not smallbook is turned on.
74 @c This matters, because of order: text flow switches columns at each page
77 @c The format faked in this source works reasonably well for smallbook,
78 @c not well for the default large-page format. This manual expects that if you
79 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
80 @c tables in question. You can turn on one without the other at your
81 @c discretion, of course.
84 @c the insn tables look just as silly in info files regardless of smallbook,
85 @c might as well show 'em anyways.
89 @dircategory Software development
91 * As: (as). The GNU assembler.
92 * Gas: (as). The GNU assembler.
100 This file documents the GNU Assembler "@value{AS}".
102 @c man begin COPYRIGHT
103 Copyright @copyright{} 1991-2015 Free Software Foundation, Inc.
105 Permission is granted to copy, distribute and/or modify this document
106 under the terms of the GNU Free Documentation License, Version 1.3
107 or any later version published by the Free Software Foundation;
108 with no Invariant Sections, with no Front-Cover Texts, and with no
109 Back-Cover Texts. A copy of the license is included in the
110 section entitled ``GNU Free Documentation License''.
116 @title Using @value{AS}
117 @subtitle The @sc{gnu} Assembler
119 @subtitle for the @value{TARGET} family
121 @ifset VERSION_PACKAGE
123 @subtitle @value{VERSION_PACKAGE}
126 @subtitle Version @value{VERSION}
129 The Free Software Foundation Inc.@: thanks The Nice Computer
130 Company of Australia for loaning Dean Elsner to write the
131 first (Vax) version of @command{as} for Project @sc{gnu}.
132 The proprietors, management and staff of TNCCA thank FSF for
133 distracting the boss while they got some work
136 @author Dean Elsner, Jay Fenlason & friends
140 \hfill {\it Using {\tt @value{AS}}}\par
141 \hfill Edited by Cygnus Support\par
143 %"boxit" macro for figures:
144 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
145 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
146 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
147 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
148 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
151 @vskip 0pt plus 1filll
152 Copyright @copyright{} 1991-2015 Free Software Foundation, Inc.
154 Permission is granted to copy, distribute and/or modify this document
155 under the terms of the GNU Free Documentation License, Version 1.3
156 or any later version published by the Free Software Foundation;
157 with no Invariant Sections, with no Front-Cover Texts, and with no
158 Back-Cover Texts. A copy of the license is included in the
159 section entitled ``GNU Free Documentation License''.
166 @top Using @value{AS}
168 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}}
169 @ifset VERSION_PACKAGE
170 @value{VERSION_PACKAGE}
172 version @value{VERSION}.
174 This version of the file describes @command{@value{AS}} configured to generate
175 code for @value{TARGET} architectures.
178 This document is distributed under the terms of the GNU Free
179 Documentation License. A copy of the license is included in the
180 section entitled ``GNU Free Documentation License''.
183 * Overview:: Overview
184 * Invoking:: Command-Line Options
186 * Sections:: Sections and Relocation
188 * Expressions:: Expressions
189 * Pseudo Ops:: Assembler Directives
191 * Object Attributes:: Object Attributes
193 * Machine Dependencies:: Machine Dependent Features
194 * Reporting Bugs:: Reporting Bugs
195 * Acknowledgements:: Who Did What
196 * GNU Free Documentation License:: GNU Free Documentation License
197 * AS Index:: AS Index
204 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
206 This version of the manual describes @command{@value{AS}} configured to generate
207 code for @value{TARGET} architectures.
211 @cindex invocation summary
212 @cindex option summary
213 @cindex summary of options
214 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
215 see @ref{Invoking,,Command-Line Options}.
217 @c man title AS the portable GNU assembler.
221 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
225 @c We don't use deffn and friends for the following because they seem
226 @c to be limited to one line for the header.
228 @c man begin SYNOPSIS
229 @value{AS} [@b{-a}[@b{cdghlns}][=@var{file}]] [@b{--alternate}] [@b{-D}]
230 [@b{--compress-debug-sections}] [@b{--nocompress-debug-sections}]
231 [@b{--debug-prefix-map} @var{old}=@var{new}]
232 [@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}]
233 [@b{--gstabs+}] [@b{--gdwarf-2}] [@b{--gdwarf-sections}]
234 [@b{--help}] [@b{-I} @var{dir}] [@b{-J}]
235 [@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}]
236 [@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}]
237 [@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}] [@b{-o}
238 @var{objfile}] [@b{-R}] [@b{--reduce-memory-overheads}] [@b{--statistics}]
239 [@b{-v}] [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}]
240 [@b{--fatal-warnings}] [@b{-w}] [@b{-x}] [@b{-Z}] [@b{@@@var{FILE}}]
241 [@b{--sectname-subst}] [@b{--size-check=[error|warning]}]
242 [@b{--target-help}] [@var{target-options}]
243 [@b{--}|@var{files} @dots{}]
245 @c Target dependent options are listed below. Keep the list sorted.
246 @c Add an empty line for separation.
249 @emph{Target AArch64 options:}
251 [@b{-mabi}=@var{ABI}]
255 @emph{Target Alpha options:}
257 [@b{-mdebug} | @b{-no-mdebug}]
258 [@b{-replace} | @b{-noreplace}]
259 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
260 [@b{-F}] [@b{-32addr}]
264 @emph{Target ARC options:}
270 @emph{Target ARM options:}
271 @c Don't document the deprecated options
272 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
273 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
274 [@b{-mfpu}=@var{floating-point-format}]
275 [@b{-mfloat-abi}=@var{abi}]
276 [@b{-meabi}=@var{ver}]
279 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
280 @b{-mapcs-reentrant}]
281 [@b{-mthumb-interwork}] [@b{-k}]
285 @emph{Target Blackfin options:}
286 [@b{-mcpu}=@var{processor}[-@var{sirevision}]]
293 @emph{Target CRIS options:}
294 [@b{--underscore} | @b{--no-underscore}]
296 [@b{--emulation=criself} | @b{--emulation=crisaout}]
297 [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}]
298 @c Deprecated -- deliberately not documented.
303 @emph{Target D10V options:}
308 @emph{Target D30V options:}
309 [@b{-O}|@b{-n}|@b{-N}]
313 @emph{Target EPIPHANY options:}
314 [@b{-mepiphany}|@b{-mepiphany16}]
318 @emph{Target H8/300 options:}
322 @c HPPA has no machine-dependent assembler options (yet).
326 @emph{Target i386 options:}
327 [@b{--32}|@b{--x32}|@b{--64}] [@b{-n}]
328 [@b{-march}=@var{CPU}[+@var{EXTENSION}@dots{}]] [@b{-mtune}=@var{CPU}]
332 @emph{Target i960 options:}
333 @c see md_parse_option in tc-i960.c
334 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
336 [@b{-b}] [@b{-no-relax}]
340 @emph{Target IA-64 options:}
341 [@b{-mconstant-gp}|@b{-mauto-pic}]
342 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
344 [@b{-mtune=itanium1}|@b{-mtune=itanium2}]
345 [@b{-munwind-check=warning}|@b{-munwind-check=error}]
346 [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}]
347 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
351 @emph{Target IP2K options:}
352 [@b{-mip2022}|@b{-mip2022ext}]
356 @emph{Target M32C options:}
357 [@b{-m32c}|@b{-m16c}] [-relax] [-h-tick-hex]
361 @emph{Target M32R options:}
362 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
367 @emph{Target M680X0 options:}
368 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
372 @emph{Target M68HC11 options:}
373 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}|@b{-mm9s12x}|@b{-mm9s12xg}]
374 [@b{-mshort}|@b{-mlong}]
375 [@b{-mshort-double}|@b{-mlong-double}]
376 [@b{--force-long-branches}] [@b{--short-branches}]
377 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
378 [@b{--print-opcodes}] [@b{--generate-example}]
382 @emph{Target MCORE options:}
383 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
384 [@b{-mcpu=[210|340]}]
388 @emph{Target Meta options:}
389 [@b{-mcpu=@var{cpu}}] [@b{-mfpu=@var{cpu}}] [@b{-mdsp=@var{cpu}}]
392 @emph{Target MICROBLAZE options:}
393 @c MicroBlaze has no machine-dependent assembler options.
397 @emph{Target MIPS options:}
398 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
399 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
400 [@b{-non_shared}] [@b{-xgot} [@b{-mvxworks-pic}]
401 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
402 [@b{-mfp64}] [@b{-mgp64}] [@b{-mfpxx}]
403 [@b{-modd-spreg}] [@b{-mno-odd-spreg}]
404 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
405 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
406 [@b{-mips32r3}] [@b{-mips32r5}] [@b{-mips32r6}] [@b{-mips64}] [@b{-mips64r2}]
407 [@b{-mips64r3}] [@b{-mips64r5}] [@b{-mips64r6}]
408 [@b{-construct-floats}] [@b{-no-construct-floats}]
409 [@b{-mnan=@var{encoding}}]
410 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
411 [@b{-mips16}] [@b{-no-mips16}]
412 [@b{-mmicromips}] [@b{-mno-micromips}]
413 [@b{-msmartmips}] [@b{-mno-smartmips}]
414 [@b{-mips3d}] [@b{-no-mips3d}]
415 [@b{-mdmx}] [@b{-no-mdmx}]
416 [@b{-mdsp}] [@b{-mno-dsp}]
417 [@b{-mdspr2}] [@b{-mno-dspr2}]
418 [@b{-mmsa}] [@b{-mno-msa}]
419 [@b{-mxpa}] [@b{-mno-xpa}]
420 [@b{-mmt}] [@b{-mno-mt}]
421 [@b{-mmcu}] [@b{-mno-mcu}]
422 [@b{-minsn32}] [@b{-mno-insn32}]
423 [@b{-mfix7000}] [@b{-mno-fix7000}]
424 [@b{-mfix-rm7000}] [@b{-mno-fix-rm7000}]
425 [@b{-mfix-vr4120}] [@b{-mno-fix-vr4120}]
426 [@b{-mfix-vr4130}] [@b{-mno-fix-vr4130}]
427 [@b{-mdebug}] [@b{-no-mdebug}]
428 [@b{-mpdr}] [@b{-mno-pdr}]
432 @emph{Target MMIX options:}
433 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
434 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
435 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
436 [@b{--linker-allocated-gregs}]
440 @emph{Target Nios II options:}
441 [@b{-relax-all}] [@b{-relax-section}] [@b{-no-relax}]
446 @emph{Target NDS32 options:}
447 [@b{-EL}] [@b{-EB}] [@b{-O}] [@b{-Os}] [@b{-mcpu=@var{cpu}}]
448 [@b{-misa=@var{isa}}] [@b{-mabi=@var{abi}}] [@b{-mall-ext}]
449 [@b{-m[no-]16-bit}] [@b{-m[no-]perf-ext}] [@b{-m[no-]perf2-ext}]
450 [@b{-m[no-]string-ext}] [@b{-m[no-]dsp-ext}] [@b{-m[no-]mac}] [@b{-m[no-]div}]
451 [@b{-m[no-]audio-isa-ext}] [@b{-m[no-]fpu-sp-ext}] [@b{-m[no-]fpu-dp-ext}]
452 [@b{-m[no-]fpu-fma}] [@b{-mfpu-freg=@var{FREG}}] [@b{-mreduced-regs}]
453 [@b{-mfull-regs}] [@b{-m[no-]dx-regs}] [@b{-mpic}] [@b{-mno-relax}]
458 @emph{Target PDP11 options:}
459 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
460 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
461 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
465 @emph{Target picoJava options:}
470 @emph{Target PowerPC options:}
472 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|@b{-m403}|@b{-m405}|
473 @b{-m440}|@b{-m464}|@b{-m476}|@b{-m7400}|@b{-m7410}|@b{-m7450}|@b{-m7455}|@b{-m750cl}|@b{-mppc64}|
474 @b{-m620}|@b{-me500}|@b{-e500x2}|@b{-me500mc}|@b{-me500mc64}|@b{-me5500}|@b{-me6500}|@b{-mppc64bridge}|
475 @b{-mbooke}|@b{-mpower4}|@b{-mpwr4}|@b{-mpower5}|@b{-mpwr5}|@b{-mpwr5x}|@b{-mpower6}|@b{-mpwr6}|
476 @b{-mpower7}|@b{-mpwr7}|@b{-mpower8}|@b{-mpwr8}|@b{-ma2}|@b{-mcell}|@b{-mspe}|@b{-mtitan}|@b{-me300}|@b{-mcom}]
477 [@b{-many}] [@b{-maltivec}|@b{-mvsx}|@b{-mhtm}|@b{-mvle}]
478 [@b{-mregnames}|@b{-mno-regnames}]
479 [@b{-mrelocatable}|@b{-mrelocatable-lib}|@b{-K PIC}] [@b{-memb}]
480 [@b{-mlittle}|@b{-mlittle-endian}|@b{-le}|@b{-mbig}|@b{-mbig-endian}|@b{-be}]
481 [@b{-msolaris}|@b{-mno-solaris}]
482 [@b{-nops=@var{count}}]
486 @emph{Target RL78 options:}
488 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
492 @emph{Target RX options:}
493 [@b{-mlittle-endian}|@b{-mbig-endian}]
494 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
495 [@b{-muse-conventional-section-names}]
496 [@b{-msmall-data-limit}]
499 [@b{-mint-register=@var{number}}]
500 [@b{-mgcc-abi}|@b{-mrx-abi}]
504 @emph{Target s390 options:}
505 [@b{-m31}|@b{-m64}] [@b{-mesa}|@b{-mzarch}] [@b{-march}=@var{CPU}]
506 [@b{-mregnames}|@b{-mno-regnames}]
507 [@b{-mwarn-areg-zero}]
511 @emph{Target SCORE options:}
512 [@b{-EB}][@b{-EL}][@b{-FIXDD}][@b{-NWARN}]
513 [@b{-SCORE5}][@b{-SCORE5U}][@b{-SCORE7}][@b{-SCORE3}]
514 [@b{-march=score7}][@b{-march=score3}]
515 [@b{-USE_R1}][@b{-KPIC}][@b{-O0}][@b{-G} @var{num}][@b{-V}]
519 @emph{Target SPARC options:}
520 @c The order here is important. See c-sparc.texi.
521 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
522 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
523 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
528 @emph{Target TIC54X options:}
529 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
530 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
534 @emph{Target TIC6X options:}
535 [@b{-march=@var{arch}}] [@b{-mbig-endian}|@b{-mlittle-endian}]
536 [@b{-mdsbt}|@b{-mno-dsbt}] [@b{-mpid=no}|@b{-mpid=near}|@b{-mpid=far}]
537 [@b{-mpic}|@b{-mno-pic}]
541 @emph{Target TILE-Gx options:}
542 [@b{-m32}|@b{-m64}][@b{-EB}][@b{-EL}]
545 @c TILEPro has no machine-dependent assembler options
549 @emph{Target Visium options:}
550 [@b{-mtune=@var{arch}}]
554 @emph{Target Xtensa options:}
555 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
556 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
557 [@b{--[no-]transform}]
558 [@b{--rename-section} @var{oldname}=@var{newname}]
559 [@b{--[no-]trampolines}]
563 @emph{Target Z80 options:}
564 [@b{-z80}] [@b{-r800}]
565 [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}]
566 [@b{ -ignore-unportable-instructions}] [@b{-Wnup}]
567 [@b{ -warn-undocumented-instructions}] [@b{-Wud}]
568 [@b{ -warn-unportable-instructions}] [@b{-Wup}]
569 [@b{ -forbid-undocumented-instructions}] [@b{-Fud}]
570 [@b{ -forbid-unportable-instructions}] [@b{-Fup}]
574 @c Z8000 has no machine-dependent assembler options
583 @include at-file.texi
586 Turn on listings, in any of a variety of ways:
590 omit false conditionals
593 omit debugging directives
596 include general information, like @value{AS} version and options passed
599 include high-level source
605 include macro expansions
608 omit forms processing
614 set the name of the listing file
617 You may combine these options; for example, use @samp{-aln} for assembly
618 listing without forms processing. The @samp{=file} option, if used, must be
619 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
622 Begin in alternate macro mode.
624 @xref{Altmacro,,@code{.altmacro}}.
627 @item --compress-debug-sections
628 Compress DWARF debug sections using zlib. The debug sections are renamed
629 to begin with @samp{.zdebug}, and the resulting object file may not be
630 compatible with older linkers and object file utilities. Note if compression
631 would make a given section @emph{larger} then it is not compressed or renamed.
634 @cindex @samp{--compress-debug-sections=} option
635 @item --compress-debug-sections=none
636 @itemx --compress-debug-sections=zlib
637 @itemx --compress-debug-sections=zlib-gnu
638 @itemx --compress-debug-sections=zlib-gabi
639 These options control how DWARF debug sections are compressed.
640 @option{--compress-debug-sections=none} is equivalent to
641 @option{--nocompress-debug-sections}.
642 @option{--compress-debug-sections=zlib} and
643 @option{--compress-debug-sections=zlib-gnu} are equivalent to
644 @option{--compress-debug-sections}.
645 @option{--compress-debug-sections=zlib-gabi} compresses
646 DWARF debug sections with SHF_COMPRESSED from the ELF ABI.
649 @item --nocompress-debug-sections
650 Do not compress DWARF debug sections. This is the default.
653 Ignored. This option is accepted for script compatibility with calls to
656 @item --debug-prefix-map @var{old}=@var{new}
657 When assembling files in directory @file{@var{old}}, record debugging
658 information describing them as in @file{@var{new}} instead.
660 @item --defsym @var{sym}=@var{value}
661 Define the symbol @var{sym} to be @var{value} before assembling the input file.
662 @var{value} must be an integer constant. As in C, a leading @samp{0x}
663 indicates a hexadecimal value, and a leading @samp{0} indicates an octal
664 value. The value of the symbol can be overridden inside a source file via the
665 use of a @code{.set} pseudo-op.
668 ``fast''---skip whitespace and comment preprocessing (assume source is
673 Generate debugging information for each assembler source line using whichever
674 debug format is preferred by the target. This currently means either STABS,
678 Generate stabs debugging information for each assembler line. This
679 may help debugging assembler code, if the debugger can handle it.
682 Generate stabs debugging information for each assembler line, with GNU
683 extensions that probably only gdb can handle, and that could make other
684 debuggers crash or refuse to read your program. This
685 may help debugging assembler code. Currently the only GNU extension is
686 the location of the current working directory at assembling time.
689 Generate DWARF2 debugging information for each assembler line. This
690 may help debugging assembler code, if the debugger can handle it. Note---this
691 option is only supported by some targets, not all of them.
693 @item --gdwarf-sections
694 Instead of creating a .debug_line section, create a series of
695 .debug_line.@var{foo} sections where @var{foo} is the name of the
696 corresponding code section. For example a code section called @var{.text.func}
697 will have its dwarf line number information placed into a section called
698 @var{.debug_line.text.func}. If the code section is just called @var{.text}
699 then debug line section will still be called just @var{.debug_line} without any
702 @item --size-check=error
703 @itemx --size-check=warning
704 Issue an error or warning for invalid ELF .size directive.
707 Print a summary of the command line options and exit.
710 Print a summary of all target specific options and exit.
713 Add directory @var{dir} to the search list for @code{.include} directives.
716 Don't warn about signed overflow.
719 @ifclear DIFF-TBL-KLUGE
720 This option is accepted but has no effect on the @value{TARGET} family.
722 @ifset DIFF-TBL-KLUGE
723 Issue warnings when difference tables altered for long displacements.
728 Keep (in the symbol table) local symbols. These symbols start with
729 system-specific local label prefixes, typically @samp{.L} for ELF systems
730 or @samp{L} for traditional a.out systems.
735 @item --listing-lhs-width=@var{number}
736 Set the maximum width, in words, of the output data column for an assembler
737 listing to @var{number}.
739 @item --listing-lhs-width2=@var{number}
740 Set the maximum width, in words, of the output data column for continuation
741 lines in an assembler listing to @var{number}.
743 @item --listing-rhs-width=@var{number}
744 Set the maximum width of an input source line, as displayed in a listing, to
747 @item --listing-cont-lines=@var{number}
748 Set the maximum number of lines printed in a listing for a single line of input
751 @item -o @var{objfile}
752 Name the object-file output from @command{@value{AS}} @var{objfile}.
755 Fold the data section into the text section.
757 @kindex --hash-size=@var{number}
758 Set the default size of GAS's hash tables to a prime number close to
759 @var{number}. Increasing this value can reduce the length of time it takes the
760 assembler to perform its tasks, at the expense of increasing the assembler's
761 memory requirements. Similarly reducing this value can reduce the memory
762 requirements at the expense of speed.
764 @item --reduce-memory-overheads
765 This option reduces GAS's memory requirements, at the expense of making the
766 assembly processes slower. Currently this switch is a synonym for
767 @samp{--hash-size=4051}, but in the future it may have other effects as well.
770 @item --sectname-subst
771 Honor substitution sequences in section names.
773 @xref{Section Name Substitutions,,@code{.section @var{name}}}.
778 Print the maximum space (in bytes) and total time (in seconds) used by
781 @item --strip-local-absolute
782 Remove local absolute symbols from the outgoing symbol table.
786 Print the @command{as} version.
789 Print the @command{as} version and exit.
793 Suppress warning messages.
795 @item --fatal-warnings
796 Treat warnings as errors.
799 Don't suppress warning messages or treat them as errors.
808 Generate an object file even after errors.
810 @item -- | @var{files} @dots{}
811 Standard input, or source files to assemble.
819 @xref{AArch64 Options}, for the options available when @value{AS} is configured
820 for the 64-bit mode of the ARM Architecture (AArch64).
825 The following options are available when @value{AS} is configured for the
826 64-bit mode of the ARM Architecture (AArch64).
829 @include c-aarch64.texi
830 @c ended inside the included file
838 @xref{Alpha Options}, for the options available when @value{AS} is configured
839 for an Alpha processor.
844 The following options are available when @value{AS} is configured for an Alpha
848 @include c-alpha.texi
849 @c ended inside the included file
856 The following options are available when @value{AS} is configured for
861 This option selects the core processor variant.
863 Select either big-endian (-EB) or little-endian (-EL) output.
868 The following options are available when @value{AS} is configured for the ARM
872 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
873 Specify which ARM processor variant is the target.
874 @item -march=@var{architecture}[+@var{extension}@dots{}]
875 Specify which ARM architecture variant is used by the target.
876 @item -mfpu=@var{floating-point-format}
877 Select which Floating Point architecture is the target.
878 @item -mfloat-abi=@var{abi}
879 Select which floating point ABI is in use.
881 Enable Thumb only instruction decoding.
882 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
883 Select which procedure calling convention is in use.
885 Select either big-endian (-EB) or little-endian (-EL) output.
886 @item -mthumb-interwork
887 Specify that the code has been generated with interworking between Thumb and
890 Turns on CodeComposer Studio assembly syntax compatibility mode.
892 Specify that PIC code has been generated.
900 @xref{Blackfin Options}, for the options available when @value{AS} is
901 configured for the Blackfin processor family.
906 The following options are available when @value{AS} is configured for
907 the Blackfin processor family.
911 @c ended inside the included file
918 See the info pages for documentation of the CRIS-specific options.
922 The following options are available when @value{AS} is configured for
925 @cindex D10V optimization
926 @cindex optimization, D10V
928 Optimize output by parallelizing instructions.
933 The following options are available when @value{AS} is configured for a D30V
936 @cindex D30V optimization
937 @cindex optimization, D30V
939 Optimize output by parallelizing instructions.
943 Warn when nops are generated.
945 @cindex D30V nops after 32-bit multiply
947 Warn when a nop after a 32-bit multiply instruction is generated.
953 The following options are available when @value{AS} is configured for the
954 Adapteva EPIPHANY series.
957 @xref{Epiphany Options}, for the options available when @value{AS} is
958 configured for an Epiphany processor.
963 The following options are available when @value{AS} is configured for
964 an Epiphany processor.
967 @include c-epiphany.texi
968 @c ended inside the included file
976 @xref{H8/300 Options}, for the options available when @value{AS} is configured
977 for an H8/300 processor.
982 The following options are available when @value{AS} is configured for an H8/300
986 @include c-h8300.texi
987 @c ended inside the included file
995 @xref{i386-Options}, for the options available when @value{AS} is
996 configured for an i386 processor.
1000 @c man begin OPTIONS
1001 The following options are available when @value{AS} is configured for
1004 @c man begin INCLUDE
1005 @include c-i386.texi
1006 @c ended inside the included file
1011 @c man begin OPTIONS
1013 The following options are available when @value{AS} is configured for the
1014 Intel 80960 processor.
1017 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
1018 Specify which variant of the 960 architecture is the target.
1021 Add code to collect statistics about branches taken.
1024 Do not alter compare-and-branch instructions for long displacements;
1031 The following options are available when @value{AS} is configured for the
1037 Specifies that the extended IP2022 instructions are allowed.
1040 Restores the default behaviour, which restricts the permitted instructions to
1041 just the basic IP2022 ones.
1047 The following options are available when @value{AS} is configured for the
1048 Renesas M32C and M16C processors.
1053 Assemble M32C instructions.
1056 Assemble M16C instructions (the default).
1059 Enable support for link-time relaxations.
1062 Support H'00 style hex constants in addition to 0x00 style.
1068 The following options are available when @value{AS} is configured for the
1069 Renesas M32R (formerly Mitsubishi M32R) series.
1074 Specify which processor in the M32R family is the target. The default
1075 is normally the M32R, but this option changes it to the M32RX.
1077 @item --warn-explicit-parallel-conflicts or --Wp
1078 Produce warning messages when questionable parallel constructs are
1081 @item --no-warn-explicit-parallel-conflicts or --Wnp
1082 Do not produce warning messages when questionable parallel constructs are
1089 The following options are available when @value{AS} is configured for the
1090 Motorola 68000 series.
1095 Shorten references to undefined symbols, to one word instead of two.
1097 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
1098 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
1099 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
1100 Specify what processor in the 68000 family is the target. The default
1101 is normally the 68020, but this can be changed at configuration time.
1103 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
1104 The target machine does (or does not) have a floating-point coprocessor.
1105 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
1106 the basic 68000 is not compatible with the 68881, a combination of the
1107 two can be specified, since it's possible to do emulation of the
1108 coprocessor instructions with the main processor.
1110 @item -m68851 | -mno-68851
1111 The target machine does (or does not) have a memory-management
1112 unit coprocessor. The default is to assume an MMU for 68020 and up.
1120 @xref{Nios II Options}, for the options available when @value{AS} is configured
1121 for an Altera Nios II processor.
1125 @c man begin OPTIONS
1126 The following options are available when @value{AS} is configured for an
1127 Altera Nios II processor.
1129 @c man begin INCLUDE
1130 @include c-nios2.texi
1131 @c ended inside the included file
1137 For details about the PDP-11 machine dependent features options,
1138 see @ref{PDP-11-Options}.
1141 @item -mpic | -mno-pic
1142 Generate position-independent (or position-dependent) code. The
1143 default is @option{-mpic}.
1146 @itemx -mall-extensions
1147 Enable all instruction set extensions. This is the default.
1149 @item -mno-extensions
1150 Disable all instruction set extensions.
1152 @item -m@var{extension} | -mno-@var{extension}
1153 Enable (or disable) a particular instruction set extension.
1156 Enable the instruction set extensions supported by a particular CPU, and
1157 disable all other extensions.
1159 @item -m@var{machine}
1160 Enable the instruction set extensions supported by a particular machine
1161 model, and disable all other extensions.
1167 The following options are available when @value{AS} is configured for
1168 a picoJava processor.
1172 @cindex PJ endianness
1173 @cindex endianness, PJ
1174 @cindex big endian output, PJ
1176 Generate ``big endian'' format output.
1178 @cindex little endian output, PJ
1180 Generate ``little endian'' format output.
1186 The following options are available when @value{AS} is configured for the
1187 Motorola 68HC11 or 68HC12 series.
1191 @item -m68hc11 | -m68hc12 | -m68hcs12 | -mm9s12x | -mm9s12xg
1192 Specify what processor is the target. The default is
1193 defined by the configuration option when building the assembler.
1195 @item --xgate-ramoffset
1196 Instruct the linker to offset RAM addresses from S12X address space into
1197 XGATE address space.
1200 Specify to use the 16-bit integer ABI.
1203 Specify to use the 32-bit integer ABI.
1205 @item -mshort-double
1206 Specify to use the 32-bit double ABI.
1209 Specify to use the 64-bit double ABI.
1211 @item --force-long-branches
1212 Relative branches are turned into absolute ones. This concerns
1213 conditional branches, unconditional branches and branches to a
1216 @item -S | --short-branches
1217 Do not turn relative branches into absolute ones
1218 when the offset is out of range.
1220 @item --strict-direct-mode
1221 Do not turn the direct addressing mode into extended addressing mode
1222 when the instruction does not support direct addressing mode.
1224 @item --print-insn-syntax
1225 Print the syntax of instruction in case of error.
1227 @item --print-opcodes
1228 Print the list of instructions with syntax and then exit.
1230 @item --generate-example
1231 Print an example of instruction for each possible instruction and then exit.
1232 This option is only useful for testing @command{@value{AS}}.
1238 The following options are available when @command{@value{AS}} is configured
1239 for the SPARC architecture:
1242 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
1243 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
1244 Explicitly select a variant of the SPARC architecture.
1246 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
1247 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
1249 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
1250 UltraSPARC extensions.
1252 @item -xarch=v8plus | -xarch=v8plusa
1253 For compatibility with the Solaris v9 assembler. These options are
1254 equivalent to -Av8plus and -Av8plusa, respectively.
1257 Warn when the assembler switches to another architecture.
1262 The following options are available when @value{AS} is configured for the 'c54x
1267 Enable extended addressing mode. All addresses and relocations will assume
1268 extended addressing (usually 23 bits).
1269 @item -mcpu=@var{CPU_VERSION}
1270 Sets the CPU version being compiled for.
1271 @item -merrors-to-file @var{FILENAME}
1272 Redirect error output to a file, for broken systems which don't support such
1273 behaviour in the shell.
1278 The following options are available when @value{AS} is configured for
1283 This option sets the largest size of an object that can be referenced
1284 implicitly with the @code{gp} register. It is only accepted for targets that
1285 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
1287 @cindex MIPS endianness
1288 @cindex endianness, MIPS
1289 @cindex big endian output, MIPS
1291 Generate ``big endian'' format output.
1293 @cindex little endian output, MIPS
1295 Generate ``little endian'' format output.
1313 Generate code for a particular MIPS Instruction Set Architecture level.
1314 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
1315 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
1316 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
1317 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips32r3},
1318 @samp{-mips32r5}, @samp{-mips32r6}, @samp{-mips64}, @samp{-mips64r2},
1319 @samp{-mips64r3}, @samp{-mips64r5}, and @samp{-mips64r6} correspond to generic
1320 MIPS V, MIPS32, MIPS32 Release 2, MIPS32 Release 3, MIPS32 Release 5, MIPS32
1321 Release 6, MIPS64, MIPS64 Release 2, MIPS64 Release 3, MIPS64 Release 5, and
1322 MIPS64 Release 6 ISA processors, respectively.
1324 @item -march=@var{cpu}
1325 Generate code for a particular MIPS CPU.
1327 @item -mtune=@var{cpu}
1328 Schedule and tune for a particular MIPS CPU.
1332 Cause nops to be inserted if the read of the destination register
1333 of an mfhi or mflo instruction occurs in the following two instructions.
1336 @itemx -mno-fix-rm7000
1337 Cause nops to be inserted if a dmult or dmultu instruction is
1338 followed by a load instruction.
1342 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
1343 section instead of the standard ELF .stabs sections.
1347 Control generation of @code{.pdr} sections.
1351 The register sizes are normally inferred from the ISA and ABI, but these
1352 flags force a certain group of registers to be treated as 32 bits wide at
1353 all times. @samp{-mgp32} controls the size of general-purpose registers
1354 and @samp{-mfp32} controls the size of floating-point registers.
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 64 bits wide at
1360 all times. @samp{-mgp64} controls the size of general-purpose registers
1361 and @samp{-mfp64} controls the size of floating-point registers.
1364 The register sizes are normally inferred from the ISA and ABI, but using
1365 this flag in combination with @samp{-mabi=32} enables an ABI variant
1366 which will operate correctly with floating-point registers which are
1370 @itemx -mno-odd-spreg
1371 Enable use of floating-point operations on odd-numbered single-precision
1372 registers when supported by the ISA. @samp{-mfpxx} implies
1373 @samp{-mno-odd-spreg}, otherwise the default is @samp{-modd-spreg}.
1377 Generate code for the MIPS 16 processor. This is equivalent to putting
1378 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
1379 turns off this option.
1382 @itemx -mno-micromips
1383 Generate code for the microMIPS processor. This is equivalent to putting
1384 @code{.set micromips} at the start of the assembly file. @samp{-mno-micromips}
1385 turns off this option. This is equivalent to putting @code{.set nomicromips}
1386 at the start of the assembly file.
1389 @itemx -mno-smartmips
1390 Enables the SmartMIPS extension to the MIPS32 instruction set. This is
1391 equivalent to putting @code{.set smartmips} at the start of the assembly file.
1392 @samp{-mno-smartmips} turns off this option.
1396 Generate code for the MIPS-3D Application Specific Extension.
1397 This tells the assembler to accept MIPS-3D instructions.
1398 @samp{-no-mips3d} turns off this option.
1402 Generate code for the MDMX Application Specific Extension.
1403 This tells the assembler to accept MDMX instructions.
1404 @samp{-no-mdmx} turns off this option.
1408 Generate code for the DSP Release 1 Application Specific Extension.
1409 This tells the assembler to accept DSP Release 1 instructions.
1410 @samp{-mno-dsp} turns off this option.
1414 Generate code for the DSP Release 2 Application Specific Extension.
1415 This option implies -mdsp.
1416 This tells the assembler to accept DSP Release 2 instructions.
1417 @samp{-mno-dspr2} turns off this option.
1421 Generate code for the MIPS SIMD Architecture Extension.
1422 This tells the assembler to accept MSA instructions.
1423 @samp{-mno-msa} turns off this option.
1427 Generate code for the MIPS eXtended Physical Address (XPA) Extension.
1428 This tells the assembler to accept XPA instructions.
1429 @samp{-mno-xpa} turns off this option.
1433 Generate code for the MT Application Specific Extension.
1434 This tells the assembler to accept MT instructions.
1435 @samp{-mno-mt} turns off this option.
1439 Generate code for the MCU Application Specific Extension.
1440 This tells the assembler to accept MCU instructions.
1441 @samp{-mno-mcu} turns off this option.
1445 Only use 32-bit instruction encodings when generating code for the
1446 microMIPS processor. This option inhibits the use of any 16-bit
1447 instructions. This is equivalent to putting @code{.set insn32} at
1448 the start of the assembly file. @samp{-mno-insn32} turns off this
1449 option. This is equivalent to putting @code{.set noinsn32} at the
1450 start of the assembly file. By default @samp{-mno-insn32} is
1451 selected, allowing all instructions to be used.
1453 @item --construct-floats
1454 @itemx --no-construct-floats
1455 The @samp{--no-construct-floats} option disables the construction of
1456 double width floating point constants by loading the two halves of the
1457 value into the two single width floating point registers that make up
1458 the double width register. By default @samp{--construct-floats} is
1459 selected, allowing construction of these floating point constants.
1461 @item --relax-branch
1462 @itemx --no-relax-branch
1463 The @samp{--relax-branch} option enables the relaxation of out-of-range
1464 branches. By default @samp{--no-relax-branch} is selected, causing any
1465 out-of-range branches to produce an error.
1467 @item -mnan=@var{encoding}
1468 Select between the IEEE 754-2008 (@option{-mnan=2008}) or the legacy
1469 (@option{-mnan=legacy}) NaN encoding format. The latter is the default.
1472 @item --emulation=@var{name}
1473 This option was formerly used to switch between ELF and ECOFF output
1474 on targets like IRIX 5 that supported both. MIPS ECOFF support was
1475 removed in GAS 2.24, so the option now serves little purpose.
1476 It is retained for backwards compatibility.
1478 The available configuration names are: @samp{mipself}, @samp{mipslelf} and
1479 @samp{mipsbelf}. Choosing @samp{mipself} now has no effect, since the output
1480 is always ELF. @samp{mipslelf} and @samp{mipsbelf} select little- and
1481 big-endian output respectively, but @samp{-EL} and @samp{-EB} are now the
1482 preferred options instead.
1485 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1492 Control how to deal with multiplication overflow and division by zero.
1493 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1494 (and only work for Instruction Set Architecture level 2 and higher);
1495 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1499 When this option is used, @command{@value{AS}} will issue a warning every
1500 time it generates a nop instruction from a macro.
1505 The following options are available when @value{AS} is configured for
1511 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1512 The command line option @samp{-nojsri2bsr} can be used to disable it.
1516 Enable or disable the silicon filter behaviour. By default this is disabled.
1517 The default can be overridden by the @samp{-sifilter} command line option.
1520 Alter jump instructions for long displacements.
1522 @item -mcpu=[210|340]
1523 Select the cpu type on the target hardware. This controls which instructions
1527 Assemble for a big endian target.
1530 Assemble for a little endian target.
1539 @xref{Meta Options}, for the options available when @value{AS} is configured
1540 for a Meta processor.
1544 @c man begin OPTIONS
1545 The following options are available when @value{AS} is configured for a
1548 @c man begin INCLUDE
1549 @include c-metag.texi
1550 @c ended inside the included file
1555 @c man begin OPTIONS
1557 See the info pages for documentation of the MMIX-specific options.
1563 @xref{NDS32 Options}, for the options available when @value{AS} is configured
1564 for a NDS32 processor.
1566 @c ended inside the included file
1570 @c man begin OPTIONS
1571 The following options are available when @value{AS} is configured for a
1574 @c man begin INCLUDE
1575 @include c-nds32.texi
1576 @c ended inside the included file
1583 @xref{PowerPC-Opts}, for the options available when @value{AS} is configured
1584 for a PowerPC processor.
1588 @c man begin OPTIONS
1589 The following options are available when @value{AS} is configured for a
1592 @c man begin INCLUDE
1594 @c ended inside the included file
1599 @c man begin OPTIONS
1601 See the info pages for documentation of the RX-specific options.
1605 The following options are available when @value{AS} is configured for the s390
1611 Select the word size, either 31/32 bits or 64 bits.
1614 Select the architecture mode, either the Enterprise System
1615 Architecture (esa) or the z/Architecture mode (zarch).
1616 @item -march=@var{processor}
1617 Specify which s390 processor variant is the target, @samp{g6}, @samp{g6},
1618 @samp{z900}, @samp{z990}, @samp{z9-109}, @samp{z9-ec}, @samp{z10},
1619 @samp{z196}, @samp{zEC12}, or @samp{z13}.
1621 @itemx -mno-regnames
1622 Allow or disallow symbolic names for registers.
1623 @item -mwarn-areg-zero
1624 Warn whenever the operand for a base or index register has been specified
1625 but evaluates to zero.
1633 @xref{TIC6X Options}, for the options available when @value{AS} is configured
1634 for a TMS320C6000 processor.
1638 @c man begin OPTIONS
1639 The following options are available when @value{AS} is configured for a
1640 TMS320C6000 processor.
1642 @c man begin INCLUDE
1643 @include c-tic6x.texi
1644 @c ended inside the included file
1652 @xref{TILE-Gx Options}, for the options available when @value{AS} is configured
1653 for a TILE-Gx processor.
1657 @c man begin OPTIONS
1658 The following options are available when @value{AS} is configured for a TILE-Gx
1661 @c man begin INCLUDE
1662 @include c-tilegx.texi
1663 @c ended inside the included file
1671 @xref{Visium Options}, for the options available when @value{AS} is configured
1672 for a Visium processor.
1676 @c man begin OPTIONS
1677 The following option is available when @value{AS} is configured for a Visium
1680 @c man begin INCLUDE
1681 @include c-visium.texi
1682 @c ended inside the included file
1690 @xref{Xtensa Options}, for the options available when @value{AS} is configured
1691 for an Xtensa processor.
1695 @c man begin OPTIONS
1696 The following options are available when @value{AS} is configured for an
1699 @c man begin INCLUDE
1700 @include c-xtensa.texi
1701 @c ended inside the included file
1706 @c man begin OPTIONS
1709 The following options are available when @value{AS} is configured for
1710 a Z80 family processor.
1713 Assemble for Z80 processor.
1715 Assemble for R800 processor.
1716 @item -ignore-undocumented-instructions
1718 Assemble undocumented Z80 instructions that also work on R800 without warning.
1719 @item -ignore-unportable-instructions
1721 Assemble all undocumented Z80 instructions without warning.
1722 @item -warn-undocumented-instructions
1724 Issue a warning for undocumented Z80 instructions that also work on R800.
1725 @item -warn-unportable-instructions
1727 Issue a warning for undocumented Z80 instructions that do not work on R800.
1728 @item -forbid-undocumented-instructions
1730 Treat all undocumented instructions as errors.
1731 @item -forbid-unportable-instructions
1733 Treat undocumented Z80 instructions that do not work on R800 as errors.
1740 * Manual:: Structure of this Manual
1741 * GNU Assembler:: The GNU Assembler
1742 * Object Formats:: Object File Formats
1743 * Command Line:: Command Line
1744 * Input Files:: Input Files
1745 * Object:: Output (Object) File
1746 * Errors:: Error and Warning Messages
1750 @section Structure of this Manual
1752 @cindex manual, structure and purpose
1753 This manual is intended to describe what you need to know to use
1754 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1755 notation for symbols, constants, and expressions; the directives that
1756 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1759 We also cover special features in the @value{TARGET}
1760 configuration of @command{@value{AS}}, including assembler directives.
1763 This manual also describes some of the machine-dependent features of
1764 various flavors of the assembler.
1767 @cindex machine instructions (not covered)
1768 On the other hand, this manual is @emph{not} intended as an introduction
1769 to programming in assembly language---let alone programming in general!
1770 In a similar vein, we make no attempt to introduce the machine
1771 architecture; we do @emph{not} describe the instruction set, standard
1772 mnemonics, registers or addressing modes that are standard to a
1773 particular architecture.
1775 You may want to consult the manufacturer's
1776 machine architecture manual for this information.
1780 For information on the H8/300 machine instruction set, see @cite{H8/300
1781 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1782 Programming Manual} (Renesas).
1785 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1786 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1787 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1788 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1791 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1795 @c I think this is premature---doc@cygnus.com, 17jan1991
1797 Throughout this manual, we assume that you are running @dfn{GNU},
1798 the portable operating system from the @dfn{Free Software
1799 Foundation, Inc.}. This restricts our attention to certain kinds of
1800 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1801 once this assumption is granted examples and definitions need less
1804 @command{@value{AS}} is part of a team of programs that turn a high-level
1805 human-readable series of instructions into a low-level
1806 computer-readable series of instructions. Different versions of
1807 @command{@value{AS}} are used for different kinds of computer.
1810 @c There used to be a section "Terminology" here, which defined
1811 @c "contents", "byte", "word", and "long". Defining "word" to any
1812 @c particular size is confusing when the .word directive may generate 16
1813 @c bits on one machine and 32 bits on another; in general, for the user
1814 @c version of this manual, none of these terms seem essential to define.
1815 @c They were used very little even in the former draft of the manual;
1816 @c this draft makes an effort to avoid them (except in names of
1820 @section The GNU Assembler
1822 @c man begin DESCRIPTION
1824 @sc{gnu} @command{as} is really a family of assemblers.
1826 This manual describes @command{@value{AS}}, a member of that family which is
1827 configured for the @value{TARGET} architectures.
1829 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1830 should find a fairly similar environment when you use it on another
1831 architecture. Each version has much in common with the others,
1832 including object file formats, most assembler directives (often called
1833 @dfn{pseudo-ops}) and assembler syntax.@refill
1835 @cindex purpose of @sc{gnu} assembler
1836 @command{@value{AS}} is primarily intended to assemble the output of the
1837 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1838 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1839 assemble correctly everything that other assemblers for the same
1840 machine would assemble.
1842 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1845 @c This remark should appear in generic version of manual; assumption
1846 @c here is that generic version sets M680x0.
1847 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1848 assembler for the same architecture; for example, we know of several
1849 incompatible versions of 680x0 assembly language syntax.
1854 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1855 program in one pass of the source file. This has a subtle impact on the
1856 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1858 @node Object Formats
1859 @section Object File Formats
1861 @cindex object file format
1862 The @sc{gnu} assembler can be configured to produce several alternative
1863 object file formats. For the most part, this does not affect how you
1864 write assembly language programs; but directives for debugging symbols
1865 are typically different in different file formats. @xref{Symbol
1866 Attributes,,Symbol Attributes}.
1869 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1870 @value{OBJ-NAME} format object files.
1872 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1874 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1875 @code{b.out} or COFF format object files.
1878 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1879 SOM or ELF format object files.
1884 @section Command Line
1886 @cindex command line conventions
1888 After the program name @command{@value{AS}}, the command line may contain
1889 options and file names. Options may appear in any order, and may be
1890 before, after, or between file names. The order of file names is
1893 @cindex standard input, as input file
1895 @file{--} (two hyphens) by itself names the standard input file
1896 explicitly, as one of the files for @command{@value{AS}} to assemble.
1898 @cindex options, command line
1899 Except for @samp{--} any command line argument that begins with a
1900 hyphen (@samp{-}) is an option. Each option changes the behavior of
1901 @command{@value{AS}}. No option changes the way another option works. An
1902 option is a @samp{-} followed by one or more letters; the case of
1903 the letter is important. All options are optional.
1905 Some options expect exactly one file name to follow them. The file
1906 name may either immediately follow the option's letter (compatible
1907 with older assemblers) or it may be the next command argument (@sc{gnu}
1908 standard). These two command lines are equivalent:
1911 @value{AS} -o my-object-file.o mumble.s
1912 @value{AS} -omy-object-file.o mumble.s
1916 @section Input Files
1919 @cindex source program
1920 @cindex files, input
1921 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1922 describe the program input to one run of @command{@value{AS}}. The program may
1923 be in one or more files; how the source is partitioned into files
1924 doesn't change the meaning of the source.
1926 @c I added "con" prefix to "catenation" just to prove I can overcome my
1927 @c APL training... doc@cygnus.com
1928 The source program is a concatenation of the text in all the files, in the
1931 @c man begin DESCRIPTION
1932 Each time you run @command{@value{AS}} it assembles exactly one source
1933 program. The source program is made up of one or more files.
1934 (The standard input is also a file.)
1936 You give @command{@value{AS}} a command line that has zero or more input file
1937 names. The input files are read (from left file name to right). A
1938 command line argument (in any position) that has no special meaning
1939 is taken to be an input file name.
1941 If you give @command{@value{AS}} no file names it attempts to read one input file
1942 from the @command{@value{AS}} standard input, which is normally your terminal. You
1943 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1946 Use @samp{--} if you need to explicitly name the standard input file
1947 in your command line.
1949 If the source is empty, @command{@value{AS}} produces a small, empty object
1954 @subheading Filenames and Line-numbers
1956 @cindex input file linenumbers
1957 @cindex line numbers, in input files
1958 There are two ways of locating a line in the input file (or files) and
1959 either may be used in reporting error messages. One way refers to a line
1960 number in a physical file; the other refers to a line number in a
1961 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1963 @dfn{Physical files} are those files named in the command line given
1964 to @command{@value{AS}}.
1966 @dfn{Logical files} are simply names declared explicitly by assembler
1967 directives; they bear no relation to physical files. Logical file names help
1968 error messages reflect the original source file, when @command{@value{AS}} source
1969 is itself synthesized from other files. @command{@value{AS}} understands the
1970 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1971 @ref{File,,@code{.file}}.
1974 @section Output (Object) File
1980 Every time you run @command{@value{AS}} it produces an output file, which is
1981 your assembly language program translated into numbers. This file
1982 is the object file. Its default name is
1990 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1992 You can give it another name by using the @option{-o} option. Conventionally,
1993 object file names end with @file{.o}. The default name is used for historical
1994 reasons: older assemblers were capable of assembling self-contained programs
1995 directly into a runnable program. (For some formats, this isn't currently
1996 possible, but it can be done for the @code{a.out} format.)
2000 The object file is meant for input to the linker @code{@value{LD}}. It contains
2001 assembled program code, information to help @code{@value{LD}} integrate
2002 the assembled program into a runnable file, and (optionally) symbolic
2003 information for the debugger.
2005 @c link above to some info file(s) like the description of a.out.
2006 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
2009 @section Error and Warning Messages
2011 @c man begin DESCRIPTION
2013 @cindex error messages
2014 @cindex warning messages
2015 @cindex messages from assembler
2016 @command{@value{AS}} may write warnings and error messages to the standard error
2017 file (usually your terminal). This should not happen when a compiler
2018 runs @command{@value{AS}} automatically. Warnings report an assumption made so
2019 that @command{@value{AS}} could keep assembling a flawed program; errors report a
2020 grave problem that stops the assembly.
2024 @cindex format of warning messages
2025 Warning messages have the format
2028 file_name:@b{NNN}:Warning Message Text
2032 @cindex line numbers, in warnings/errors
2033 (where @b{NNN} is a line number). If a logical file name has been given
2034 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
2035 the current input file is used. If a logical line number was given
2037 (@pxref{Line,,@code{.line}})
2039 then it is used to calculate the number printed,
2040 otherwise the actual line in the current source file is printed. The
2041 message text is intended to be self explanatory (in the grand Unix
2044 @cindex format of error messages
2045 Error messages have the format
2047 file_name:@b{NNN}:FATAL:Error Message Text
2049 The file name and line number are derived as for warning
2050 messages. The actual message text may be rather less explanatory
2051 because many of them aren't supposed to happen.
2054 @chapter Command-Line Options
2056 @cindex options, all versions of assembler
2057 This chapter describes command-line options available in @emph{all}
2058 versions of the @sc{gnu} assembler; see @ref{Machine Dependencies},
2059 for options specific
2061 to the @value{TARGET} target.
2064 to particular machine architectures.
2067 @c man begin DESCRIPTION
2069 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
2070 you can use the @samp{-Wa} option to pass arguments through to the assembler.
2071 The assembler arguments must be separated from each other (and the @samp{-Wa})
2072 by commas. For example:
2075 gcc -c -g -O -Wa,-alh,-L file.c
2079 This passes two options to the assembler: @samp{-alh} (emit a listing to
2080 standard output with high-level and assembly source) and @samp{-L} (retain
2081 local symbols in the symbol table).
2083 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
2084 command-line options are automatically passed to the assembler by the compiler.
2085 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
2086 precisely what options it passes to each compilation pass, including the
2092 * a:: -a[cdghlns] enable listings
2093 * alternate:: --alternate enable alternate macro syntax
2094 * D:: -D for compatibility
2095 * f:: -f to work faster
2096 * I:: -I for .include search path
2097 @ifclear DIFF-TBL-KLUGE
2098 * K:: -K for compatibility
2100 @ifset DIFF-TBL-KLUGE
2101 * K:: -K for difference tables
2104 * L:: -L to retain local symbols
2105 * listing:: --listing-XXX to configure listing output
2106 * M:: -M or --mri to assemble in MRI compatibility mode
2107 * MD:: --MD for dependency tracking
2108 * o:: -o to name the object file
2109 * R:: -R to join data and text sections
2110 * statistics:: --statistics to see statistics about assembly
2111 * traditional-format:: --traditional-format for compatible output
2112 * v:: -v to announce version
2113 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
2114 * Z:: -Z to make object file even after errors
2118 @section Enable Listings: @option{-a[cdghlns]}
2128 @cindex listings, enabling
2129 @cindex assembly listings, enabling
2131 These options enable listing output from the assembler. By itself,
2132 @samp{-a} requests high-level, assembly, and symbols listing.
2133 You can use other letters to select specific options for the list:
2134 @samp{-ah} requests a high-level language listing,
2135 @samp{-al} requests an output-program assembly listing, and
2136 @samp{-as} requests a symbol table listing.
2137 High-level listings require that a compiler debugging option like
2138 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
2141 Use the @samp{-ag} option to print a first section with general assembly
2142 information, like @value{AS} version, switches passed, or time stamp.
2144 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
2145 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
2146 other conditional), or a true @code{.if} followed by an @code{.else}, will be
2147 omitted from the listing.
2149 Use the @samp{-ad} option to omit debugging directives from the
2152 Once you have specified one of these options, you can further control
2153 listing output and its appearance using the directives @code{.list},
2154 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
2156 The @samp{-an} option turns off all forms processing.
2157 If you do not request listing output with one of the @samp{-a} options, the
2158 listing-control directives have no effect.
2160 The letters after @samp{-a} may be combined into one option,
2161 @emph{e.g.}, @samp{-aln}.
2163 Note if the assembler source is coming from the standard input (e.g.,
2165 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
2166 is being used) then the listing will not contain any comments or preprocessor
2167 directives. This is because the listing code buffers input source lines from
2168 stdin only after they have been preprocessed by the assembler. This reduces
2169 memory usage and makes the code more efficient.
2172 @section @option{--alternate}
2175 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
2178 @section @option{-D}
2181 This option has no effect whatsoever, but it is accepted to make it more
2182 likely that scripts written for other assemblers also work with
2183 @command{@value{AS}}.
2186 @section Work Faster: @option{-f}
2189 @cindex trusted compiler
2190 @cindex faster processing (@option{-f})
2191 @samp{-f} should only be used when assembling programs written by a
2192 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
2193 and comment preprocessing on
2194 the input file(s) before assembling them. @xref{Preprocessing,
2198 @emph{Warning:} if you use @samp{-f} when the files actually need to be
2199 preprocessed (if they contain comments, for example), @command{@value{AS}} does
2204 @section @code{.include} Search Path: @option{-I} @var{path}
2206 @kindex -I @var{path}
2207 @cindex paths for @code{.include}
2208 @cindex search path for @code{.include}
2209 @cindex @code{include} directive search path
2210 Use this option to add a @var{path} to the list of directories
2211 @command{@value{AS}} searches for files specified in @code{.include}
2212 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
2213 many times as necessary to include a variety of paths. The current
2214 working directory is always searched first; after that, @command{@value{AS}}
2215 searches any @samp{-I} directories in the same order as they were
2216 specified (left to right) on the command line.
2219 @section Difference Tables: @option{-K}
2222 @ifclear DIFF-TBL-KLUGE
2223 On the @value{TARGET} family, this option is allowed, but has no effect. It is
2224 permitted for compatibility with the @sc{gnu} assembler on other platforms,
2225 where it can be used to warn when the assembler alters the machine code
2226 generated for @samp{.word} directives in difference tables. The @value{TARGET}
2227 family does not have the addressing limitations that sometimes lead to this
2228 alteration on other platforms.
2231 @ifset DIFF-TBL-KLUGE
2232 @cindex difference tables, warning
2233 @cindex warning for altered difference tables
2234 @command{@value{AS}} sometimes alters the code emitted for directives of the
2235 form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}.
2236 You can use the @samp{-K} option if you want a warning issued when this
2241 @section Include Local Symbols: @option{-L}
2244 @cindex local symbols, retaining in output
2245 Symbols beginning with system-specific local label prefixes, typically
2246 @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are
2247 called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see
2248 such symbols when debugging, because they are intended for the use of
2249 programs (like compilers) that compose assembler programs, not for your
2250 notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard
2251 such symbols, so you do not normally debug with them.
2253 This option tells @command{@value{AS}} to retain those local symbols
2254 in the object file. Usually if you do this you also tell the linker
2255 @code{@value{LD}} to preserve those symbols.
2258 @section Configuring listing output: @option{--listing}
2260 The listing feature of the assembler can be enabled via the command line switch
2261 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
2262 hex dump of the corresponding locations in the output object file, and displays
2263 them as a listing file. The format of this listing can be controlled by
2264 directives inside the assembler source (i.e., @code{.list} (@pxref{List}),
2265 @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}),
2266 @code{.psize} (@pxref{Psize}), and
2267 @code{.eject} (@pxref{Eject}) and also by the following switches:
2270 @item --listing-lhs-width=@samp{number}
2271 @kindex --listing-lhs-width
2272 @cindex Width of first line disassembly output
2273 Sets the maximum width, in words, of the first line of the hex byte dump. This
2274 dump appears on the left hand side of the listing output.
2276 @item --listing-lhs-width2=@samp{number}
2277 @kindex --listing-lhs-width2
2278 @cindex Width of continuation lines of disassembly output
2279 Sets the maximum width, in words, of any further lines of the hex byte dump for
2280 a given input source line. If this value is not specified, it defaults to being
2281 the same as the value specified for @samp{--listing-lhs-width}. If neither
2282 switch is used the default is to one.
2284 @item --listing-rhs-width=@samp{number}
2285 @kindex --listing-rhs-width
2286 @cindex Width of source line output
2287 Sets the maximum width, in characters, of the source line that is displayed
2288 alongside the hex dump. The default value for this parameter is 100. The
2289 source line is displayed on the right hand side of the listing output.
2291 @item --listing-cont-lines=@samp{number}
2292 @kindex --listing-cont-lines
2293 @cindex Maximum number of continuation lines
2294 Sets the maximum number of continuation lines of hex dump that will be
2295 displayed for a given single line of source input. The default value is 4.
2299 @section Assemble in MRI Compatibility Mode: @option{-M}
2302 @cindex MRI compatibility mode
2303 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
2304 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
2305 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
2306 configured target) assembler from Microtec Research. The exact nature of the
2307 MRI syntax will not be documented here; see the MRI manuals for more
2308 information. Note in particular that the handling of macros and macro
2309 arguments is somewhat different. The purpose of this option is to permit
2310 assembling existing MRI assembler code using @command{@value{AS}}.
2312 The MRI compatibility is not complete. Certain operations of the MRI assembler
2313 depend upon its object file format, and can not be supported using other object
2314 file formats. Supporting these would require enhancing each object file format
2315 individually. These are:
2318 @item global symbols in common section
2320 The m68k MRI assembler supports common sections which are merged by the linker.
2321 Other object file formats do not support this. @command{@value{AS}} handles
2322 common sections by treating them as a single common symbol. It permits local
2323 symbols to be defined within a common section, but it can not support global
2324 symbols, since it has no way to describe them.
2326 @item complex relocations
2328 The MRI assemblers support relocations against a negated section address, and
2329 relocations which combine the start addresses of two or more sections. These
2330 are not support by other object file formats.
2332 @item @code{END} pseudo-op specifying start address
2334 The MRI @code{END} pseudo-op permits the specification of a start address.
2335 This is not supported by other object file formats. The start address may
2336 instead be specified using the @option{-e} option to the linker, or in a linker
2339 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
2341 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
2342 name to the output file. This is not supported by other object file formats.
2344 @item @code{ORG} pseudo-op
2346 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
2347 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
2348 which changes the location within the current section. Absolute sections are
2349 not supported by other object file formats. The address of a section may be
2350 assigned within a linker script.
2353 There are some other features of the MRI assembler which are not supported by
2354 @command{@value{AS}}, typically either because they are difficult or because they
2355 seem of little consequence. Some of these may be supported in future releases.
2359 @item EBCDIC strings
2361 EBCDIC strings are not supported.
2363 @item packed binary coded decimal
2365 Packed binary coded decimal is not supported. This means that the @code{DC.P}
2366 and @code{DCB.P} pseudo-ops are not supported.
2368 @item @code{FEQU} pseudo-op
2370 The m68k @code{FEQU} pseudo-op is not supported.
2372 @item @code{NOOBJ} pseudo-op
2374 The m68k @code{NOOBJ} pseudo-op is not supported.
2376 @item @code{OPT} branch control options
2378 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
2379 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
2380 relaxes all branches, whether forward or backward, to an appropriate size, so
2381 these options serve no purpose.
2383 @item @code{OPT} list control options
2385 The following m68k @code{OPT} list control options are ignored: @code{C},
2386 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
2387 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
2389 @item other @code{OPT} options
2391 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
2392 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
2394 @item @code{OPT} @code{D} option is default
2396 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
2397 @code{OPT NOD} may be used to turn it off.
2399 @item @code{XREF} pseudo-op.
2401 The m68k @code{XREF} pseudo-op is ignored.
2403 @item @code{.debug} pseudo-op
2405 The i960 @code{.debug} pseudo-op is not supported.
2407 @item @code{.extended} pseudo-op
2409 The i960 @code{.extended} pseudo-op is not supported.
2411 @item @code{.list} pseudo-op.
2413 The various options of the i960 @code{.list} pseudo-op are not supported.
2415 @item @code{.optimize} pseudo-op
2417 The i960 @code{.optimize} pseudo-op is not supported.
2419 @item @code{.output} pseudo-op
2421 The i960 @code{.output} pseudo-op is not supported.
2423 @item @code{.setreal} pseudo-op
2425 The i960 @code{.setreal} pseudo-op is not supported.
2430 @section Dependency Tracking: @option{--MD}
2433 @cindex dependency tracking
2436 @command{@value{AS}} can generate a dependency file for the file it creates. This
2437 file consists of a single rule suitable for @code{make} describing the
2438 dependencies of the main source file.
2440 The rule is written to the file named in its argument.
2442 This feature is used in the automatic updating of makefiles.
2445 @section Name the Object File: @option{-o}
2448 @cindex naming object file
2449 @cindex object file name
2450 There is always one object file output when you run @command{@value{AS}}. By
2451 default it has the name
2454 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
2468 You use this option (which takes exactly one filename) to give the
2469 object file a different name.
2471 Whatever the object file is called, @command{@value{AS}} overwrites any
2472 existing file of the same name.
2475 @section Join Data and Text Sections: @option{-R}
2478 @cindex data and text sections, joining
2479 @cindex text and data sections, joining
2480 @cindex joining text and data sections
2481 @cindex merging text and data sections
2482 @option{-R} tells @command{@value{AS}} to write the object file as if all
2483 data-section data lives in the text section. This is only done at
2484 the very last moment: your binary data are the same, but data
2485 section parts are relocated differently. The data section part of
2486 your object file is zero bytes long because all its bytes are
2487 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
2489 When you specify @option{-R} it would be possible to generate shorter
2490 address displacements (because we do not have to cross between text and
2491 data section). We refrain from doing this simply for compatibility with
2492 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
2495 When @command{@value{AS}} is configured for COFF or ELF output,
2496 this option is only useful if you use sections named @samp{.text} and
2501 @option{-R} is not supported for any of the HPPA targets. Using
2502 @option{-R} generates a warning from @command{@value{AS}}.
2506 @section Display Assembly Statistics: @option{--statistics}
2508 @kindex --statistics
2509 @cindex statistics, about assembly
2510 @cindex time, total for assembly
2511 @cindex space used, maximum for assembly
2512 Use @samp{--statistics} to display two statistics about the resources used by
2513 @command{@value{AS}}: the maximum amount of space allocated during the assembly
2514 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
2517 @node traditional-format
2518 @section Compatible Output: @option{--traditional-format}
2520 @kindex --traditional-format
2521 For some targets, the output of @command{@value{AS}} is different in some ways
2522 from the output of some existing assembler. This switch requests
2523 @command{@value{AS}} to use the traditional format instead.
2525 For example, it disables the exception frame optimizations which
2526 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
2529 @section Announce Version: @option{-v}
2533 @cindex assembler version
2534 @cindex version of assembler
2535 You can find out what version of as is running by including the
2536 option @samp{-v} (which you can also spell as @samp{-version}) on the
2540 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
2542 @command{@value{AS}} should never give a warning or error message when
2543 assembling compiler output. But programs written by people often
2544 cause @command{@value{AS}} to give a warning that a particular assumption was
2545 made. All such warnings are directed to the standard error file.
2549 @cindex suppressing warnings
2550 @cindex warnings, suppressing
2551 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
2552 This only affects the warning messages: it does not change any particular of
2553 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
2556 @kindex --fatal-warnings
2557 @cindex errors, caused by warnings
2558 @cindex warnings, causing error
2559 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
2560 files that generate warnings to be in error.
2563 @cindex warnings, switching on
2564 You can switch these options off again by specifying @option{--warn}, which
2565 causes warnings to be output as usual.
2568 @section Generate Object File in Spite of Errors: @option{-Z}
2569 @cindex object file, after errors
2570 @cindex errors, continuing after
2571 After an error message, @command{@value{AS}} normally produces no output. If for
2572 some reason you are interested in object file output even after
2573 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
2574 option. If there are any errors, @command{@value{AS}} continues anyways, and
2575 writes an object file after a final warning message of the form @samp{@var{n}
2576 errors, @var{m} warnings, generating bad object file.}
2581 @cindex machine-independent syntax
2582 @cindex syntax, machine-independent
2583 This chapter describes the machine-independent syntax allowed in a
2584 source file. @command{@value{AS}} syntax is similar to what many other
2585 assemblers use; it is inspired by the BSD 4.2
2590 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
2594 * Preprocessing:: Preprocessing
2595 * Whitespace:: Whitespace
2596 * Comments:: Comments
2597 * Symbol Intro:: Symbols
2598 * Statements:: Statements
2599 * Constants:: Constants
2603 @section Preprocessing
2605 @cindex preprocessing
2606 The @command{@value{AS}} internal preprocessor:
2608 @cindex whitespace, removed by preprocessor
2610 adjusts and removes extra whitespace. It leaves one space or tab before
2611 the keywords on a line, and turns any other whitespace on the line into
2614 @cindex comments, removed by preprocessor
2616 removes all comments, replacing them with a single space, or an
2617 appropriate number of newlines.
2619 @cindex constants, converted by preprocessor
2621 converts character constants into the appropriate numeric values.
2624 It does not do macro processing, include file handling, or
2625 anything else you may get from your C compiler's preprocessor. You can
2626 do include file processing with the @code{.include} directive
2627 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2628 to get other ``CPP'' style preprocessing by giving the input file a
2629 @samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of
2630 Output, gcc.info, Using GNU CC}.
2632 Excess whitespace, comments, and character constants
2633 cannot be used in the portions of the input text that are not
2636 @cindex turning preprocessing on and off
2637 @cindex preprocessing, turning on and off
2640 If the first line of an input file is @code{#NO_APP} or if you use the
2641 @samp{-f} option, whitespace and comments are not removed from the input file.
2642 Within an input file, you can ask for whitespace and comment removal in
2643 specific portions of the by putting a line that says @code{#APP} before the
2644 text that may contain whitespace or comments, and putting a line that says
2645 @code{#NO_APP} after this text. This feature is mainly intend to support
2646 @code{asm} statements in compilers whose output is otherwise free of comments
2653 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2654 Whitespace is used to separate symbols, and to make programs neater for
2655 people to read. Unless within character constants
2656 (@pxref{Characters,,Character Constants}), any whitespace means the same
2657 as exactly one space.
2663 There are two ways of rendering comments to @command{@value{AS}}. In both
2664 cases the comment is equivalent to one space.
2666 Anything from @samp{/*} through the next @samp{*/} is a comment.
2667 This means you may not nest these comments.
2671 The only way to include a newline ('\n') in a comment
2672 is to use this sort of comment.
2675 /* This sort of comment does not nest. */
2678 @cindex line comment character
2679 Anything from a @dfn{line comment} character up to the next newline is
2680 considered a comment and is ignored. The line comment character is target
2681 specific, and some targets multiple comment characters. Some targets also have
2682 line comment characters that only work if they are the first character on a
2683 line. Some targets use a sequence of two characters to introduce a line
2684 comment. Some targets can also change their line comment characters depending
2685 upon command line options that have been used. For more details see the
2686 @emph{Syntax} section in the documentation for individual targets.
2688 If the line comment character is the hash sign (@samp{#}) then it still has the
2689 special ability to enable and disable preprocessing (@pxref{Preprocessing}) and
2690 to specify logical line numbers:
2693 @cindex lines starting with @code{#}
2694 @cindex logical line numbers
2695 To be compatible with past assemblers, lines that begin with @samp{#} have a
2696 special interpretation. Following the @samp{#} should be an absolute
2697 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2698 line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a
2699 new logical file name. The rest of the line, if any, should be whitespace.
2701 If the first non-whitespace characters on the line are not numeric,
2702 the line is ignored. (Just like a comment.)
2705 # This is an ordinary comment.
2706 # 42-6 "new_file_name" # New logical file name
2707 # This is logical line # 36.
2709 This feature is deprecated, and may disappear from future versions
2710 of @command{@value{AS}}.
2715 @cindex characters used in symbols
2716 @ifclear SPECIAL-SYMS
2717 A @dfn{symbol} is one or more characters chosen from the set of all
2718 letters (both upper and lower case), digits and the three characters
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
2726 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2732 On most machines, you can also use @code{$} in symbol names; exceptions
2733 are noted in @ref{Machine Dependencies}.
2735 No symbol may begin with a digit. Case is significant.
2736 There is no length limit: all characters are significant. Multibyte characters
2737 are supported. Symbols are delimited by characters not in that set, or by the
2738 beginning of a file (since the source program must end with a newline, the end
2739 of a file is not a possible symbol delimiter). @xref{Symbols}.
2740 @cindex length of symbols
2745 @cindex statements, structure of
2746 @cindex line separator character
2747 @cindex statement separator character
2749 A @dfn{statement} ends at a newline character (@samp{\n}) or a
2750 @dfn{line separator character}. The line separator character is target
2751 specific and described in the @emph{Syntax} section of each
2752 target's documentation. Not all targets support a line separator character.
2753 The newline or line separator character is considered to be part of the
2754 preceding statement. Newlines and separators within character constants are an
2755 exception: they do not end statements.
2757 @cindex newline, required at file end
2758 @cindex EOF, newline must precede
2759 It is an error to end any statement with end-of-file: the last
2760 character of any input file should be a newline.@refill
2762 An empty statement is allowed, and may include whitespace. It is ignored.
2764 @cindex instructions and directives
2765 @cindex directives and instructions
2766 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2767 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2769 A statement begins with zero or more labels, optionally followed by a
2770 key symbol which determines what kind of statement it is. The key
2771 symbol determines the syntax of the rest of the statement. If the
2772 symbol begins with a dot @samp{.} then the statement is an assembler
2773 directive: typically valid for any computer. If the symbol begins with
2774 a letter the statement is an assembly language @dfn{instruction}: it
2775 assembles into a machine language instruction.
2777 Different versions of @command{@value{AS}} for different computers
2778 recognize different instructions. In fact, the same symbol may
2779 represent a different instruction in a different computer's assembly
2783 @cindex @code{:} (label)
2784 @cindex label (@code{:})
2785 A label is a symbol immediately followed by a colon (@code{:}).
2786 Whitespace before a label or after a colon is permitted, but you may not
2787 have whitespace between a label's symbol and its colon. @xref{Labels}.
2790 For HPPA targets, labels need not be immediately followed by a colon, but
2791 the definition of a label must begin in column zero. This also implies that
2792 only one label may be defined on each line.
2796 label: .directive followed by something
2797 another_label: # This is an empty statement.
2798 instruction operand_1, operand_2, @dots{}
2805 A constant is a number, written so that its value is known by
2806 inspection, without knowing any context. Like this:
2809 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2810 .ascii "Ring the bell\7" # A string constant.
2811 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2812 .float 0f-314159265358979323846264338327\
2813 95028841971.693993751E-40 # - pi, a flonum.
2818 * Characters:: Character Constants
2819 * Numbers:: Number Constants
2823 @subsection Character Constants
2825 @cindex character constants
2826 @cindex constants, character
2827 There are two kinds of character constants. A @dfn{character} stands
2828 for one character in one byte and its value may be used in
2829 numeric expressions. String constants (properly called string
2830 @emph{literals}) are potentially many bytes and their values may not be
2831 used in arithmetic expressions.
2835 * Chars:: Characters
2839 @subsubsection Strings
2841 @cindex string constants
2842 @cindex constants, string
2843 A @dfn{string} is written between double-quotes. It may contain
2844 double-quotes or null characters. The way to get special characters
2845 into a string is to @dfn{escape} these characters: precede them with
2846 a backslash @samp{\} character. For example @samp{\\} represents
2847 one backslash: the first @code{\} is an escape which tells
2848 @command{@value{AS}} to interpret the second character literally as a backslash
2849 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2850 escape character). The complete list of escapes follows.
2852 @cindex escape codes, character
2853 @cindex character escape codes
2856 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2858 @cindex @code{\b} (backspace character)
2859 @cindex backspace (@code{\b})
2861 Mnemonic for backspace; for ASCII this is octal code 010.
2864 @c Mnemonic for EOText; for ASCII this is octal code 004.
2866 @cindex @code{\f} (formfeed character)
2867 @cindex formfeed (@code{\f})
2869 Mnemonic for FormFeed; for ASCII this is octal code 014.
2871 @cindex @code{\n} (newline character)
2872 @cindex newline (@code{\n})
2874 Mnemonic for newline; for ASCII this is octal code 012.
2877 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2879 @cindex @code{\r} (carriage return character)
2880 @cindex carriage return (@code{\r})
2882 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2885 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2886 @c other assemblers.
2888 @cindex @code{\t} (tab)
2889 @cindex tab (@code{\t})
2891 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2894 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2895 @c @item \x @var{digit} @var{digit} @var{digit}
2896 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2898 @cindex @code{\@var{ddd}} (octal character code)
2899 @cindex octal character code (@code{\@var{ddd}})
2900 @item \ @var{digit} @var{digit} @var{digit}
2901 An octal character code. The numeric code is 3 octal digits.
2902 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2903 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2905 @cindex @code{\@var{xd...}} (hex character code)
2906 @cindex hex character code (@code{\@var{xd...}})
2907 @item \@code{x} @var{hex-digits...}
2908 A hex character code. All trailing hex digits are combined. Either upper or
2909 lower case @code{x} works.
2911 @cindex @code{\\} (@samp{\} character)
2912 @cindex backslash (@code{\\})
2914 Represents one @samp{\} character.
2917 @c Represents one @samp{'} (accent acute) character.
2918 @c This is needed in single character literals
2919 @c (@xref{Characters,,Character Constants}.) to represent
2922 @cindex @code{\"} (doublequote character)
2923 @cindex doublequote (@code{\"})
2925 Represents one @samp{"} character. Needed in strings to represent
2926 this character, because an unescaped @samp{"} would end the string.
2928 @item \ @var{anything-else}
2929 Any other character when escaped by @kbd{\} gives a warning, but
2930 assembles as if the @samp{\} was not present. The idea is that if
2931 you used an escape sequence you clearly didn't want the literal
2932 interpretation of the following character. However @command{@value{AS}} has no
2933 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2934 code and warns you of the fact.
2937 Which characters are escapable, and what those escapes represent,
2938 varies widely among assemblers. The current set is what we think
2939 the BSD 4.2 assembler recognizes, and is a subset of what most C
2940 compilers recognize. If you are in doubt, do not use an escape
2944 @subsubsection Characters
2946 @cindex single character constant
2947 @cindex character, single
2948 @cindex constant, single character
2949 A single character may be written as a single quote immediately
2950 followed by that character. The same escapes apply to characters as
2951 to strings. So if you want to write the character backslash, you
2952 must write @kbd{'\\} where the first @code{\} escapes the second
2953 @code{\}. As you can see, the quote is an acute accent, not a
2954 grave accent. A newline
2956 @ifclear abnormal-separator
2957 (or semicolon @samp{;})
2959 @ifset abnormal-separator
2961 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2966 immediately following an acute accent is taken as a literal character
2967 and does not count as the end of a statement. The value of a character
2968 constant in a numeric expression is the machine's byte-wide code for
2969 that character. @command{@value{AS}} assumes your character code is ASCII:
2970 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2973 @subsection Number Constants
2975 @cindex constants, number
2976 @cindex number constants
2977 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2978 are stored in the target machine. @emph{Integers} are numbers that
2979 would fit into an @code{int} in the C language. @emph{Bignums} are
2980 integers, but they are stored in more than 32 bits. @emph{Flonums}
2981 are floating point numbers, described below.
2984 * Integers:: Integers
2989 * Bit Fields:: Bit Fields
2995 @subsubsection Integers
2997 @cindex constants, integer
2999 @cindex binary integers
3000 @cindex integers, binary
3001 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
3002 the binary digits @samp{01}.
3004 @cindex octal integers
3005 @cindex integers, octal
3006 An octal integer is @samp{0} followed by zero or more of the octal
3007 digits (@samp{01234567}).
3009 @cindex decimal integers
3010 @cindex integers, decimal
3011 A decimal integer starts with a non-zero digit followed by zero or
3012 more digits (@samp{0123456789}).
3014 @cindex hexadecimal integers
3015 @cindex integers, hexadecimal
3016 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
3017 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
3019 Integers have the usual values. To denote a negative integer, use
3020 the prefix operator @samp{-} discussed under expressions
3021 (@pxref{Prefix Ops,,Prefix Operators}).
3024 @subsubsection Bignums
3027 @cindex constants, bignum
3028 A @dfn{bignum} has the same syntax and semantics as an integer
3029 except that the number (or its negative) takes more than 32 bits to
3030 represent in binary. The distinction is made because in some places
3031 integers are permitted while bignums are not.
3034 @subsubsection Flonums
3036 @cindex floating point numbers
3037 @cindex constants, floating point
3039 @cindex precision, floating point
3040 A @dfn{flonum} represents a floating point number. The translation is
3041 indirect: a decimal floating point number from the text is converted by
3042 @command{@value{AS}} to a generic binary floating point number of more than
3043 sufficient precision. This generic floating point number is converted
3044 to a particular computer's floating point format (or formats) by a
3045 portion of @command{@value{AS}} specialized to that computer.
3047 A flonum is written by writing (in order)
3052 (@samp{0} is optional on the HPPA.)
3056 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
3058 @kbd{e} is recommended. Case is not important.
3060 @c FIXME: verify if flonum syntax really this vague for most cases
3061 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
3062 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
3065 On the H8/300, Renesas / SuperH SH,
3066 and AMD 29K architectures, the letter must be
3067 one of the letters @samp{DFPRSX} (in upper or lower case).
3069 On the ARC, the letter must be one of the letters @samp{DFRS}
3070 (in upper or lower case).
3072 On the Intel 960 architecture, the letter must be
3073 one of the letters @samp{DFT} (in upper or lower case).
3075 On the HPPA architecture, the letter must be @samp{E} (upper case only).
3079 One of the letters @samp{DFRS} (in upper or lower case).
3082 One of the letters @samp{DFPRSX} (in upper or lower case).
3085 The letter @samp{E} (upper case only).
3088 One of the letters @samp{DFT} (in upper or lower case).
3093 An optional sign: either @samp{+} or @samp{-}.
3096 An optional @dfn{integer part}: zero or more decimal digits.
3099 An optional @dfn{fractional part}: @samp{.} followed by zero
3100 or more decimal digits.
3103 An optional exponent, consisting of:
3107 An @samp{E} or @samp{e}.
3108 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
3109 @c principle this can perfectly well be different on different targets.
3111 Optional sign: either @samp{+} or @samp{-}.
3113 One or more decimal digits.
3118 At least one of the integer part or the fractional part must be
3119 present. The floating point number has the usual base-10 value.
3121 @command{@value{AS}} does all processing using integers. Flonums are computed
3122 independently of any floating point hardware in the computer running
3123 @command{@value{AS}}.
3127 @c Bit fields are written as a general facility but are also controlled
3128 @c by a conditional-compilation flag---which is as of now (21mar91)
3129 @c turned on only by the i960 config of GAS.
3131 @subsubsection Bit Fields
3134 @cindex constants, bit field
3135 You can also define numeric constants as @dfn{bit fields}.
3136 Specify two numbers separated by a colon---
3138 @var{mask}:@var{value}
3141 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
3144 The resulting number is then packed
3146 @c this conditional paren in case bit fields turned on elsewhere than 960
3147 (in host-dependent byte order)
3149 into a field whose width depends on which assembler directive has the
3150 bit-field as its argument. Overflow (a result from the bitwise and
3151 requiring more binary digits to represent) is not an error; instead,
3152 more constants are generated, of the specified width, beginning with the
3153 least significant digits.@refill
3155 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
3156 @code{.short}, and @code{.word} accept bit-field arguments.
3161 @chapter Sections and Relocation
3166 * Secs Background:: Background
3167 * Ld Sections:: Linker Sections
3168 * As Sections:: Assembler Internal Sections
3169 * Sub-Sections:: Sub-Sections
3173 @node Secs Background
3176 Roughly, a section is a range of addresses, with no gaps; all data
3177 ``in'' those addresses is treated the same for some particular purpose.
3178 For example there may be a ``read only'' section.
3180 @cindex linker, and assembler
3181 @cindex assembler, and linker
3182 The linker @code{@value{LD}} reads many object files (partial programs) and
3183 combines their contents to form a runnable program. When @command{@value{AS}}
3184 emits an object file, the partial program is assumed to start at address 0.
3185 @code{@value{LD}} assigns the final addresses for the partial program, so that
3186 different partial programs do not overlap. This is actually an
3187 oversimplification, but it suffices to explain how @command{@value{AS}} uses
3190 @code{@value{LD}} moves blocks of bytes of your program to their run-time
3191 addresses. These blocks slide to their run-time addresses as rigid
3192 units; their length does not change and neither does the order of bytes
3193 within them. Such a rigid unit is called a @emph{section}. Assigning
3194 run-time addresses to sections is called @dfn{relocation}. It includes
3195 the task of adjusting mentions of object-file addresses so they refer to
3196 the proper run-time addresses.
3198 For the H8/300, and for the Renesas / SuperH SH,
3199 @command{@value{AS}} pads sections if needed to
3200 ensure they end on a word (sixteen bit) boundary.
3203 @cindex standard assembler sections
3204 An object file written by @command{@value{AS}} has at least three sections, any
3205 of which may be empty. These are named @dfn{text}, @dfn{data} and
3210 When it generates COFF or ELF output,
3212 @command{@value{AS}} can also generate whatever other named sections you specify
3213 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
3214 If you do not use any directives that place output in the @samp{.text}
3215 or @samp{.data} sections, these sections still exist, but are empty.
3220 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
3222 @command{@value{AS}} can also generate whatever other named sections you
3223 specify using the @samp{.space} and @samp{.subspace} directives. See
3224 @cite{HP9000 Series 800 Assembly Language Reference Manual}
3225 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
3226 assembler directives.
3229 Additionally, @command{@value{AS}} uses different names for the standard
3230 text, data, and bss sections when generating SOM output. Program text
3231 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
3232 BSS into @samp{$BSS$}.
3236 Within the object file, the text section starts at address @code{0}, the
3237 data section follows, and the bss section follows the data section.
3240 When generating either SOM or ELF output files on the HPPA, the text
3241 section starts at address @code{0}, the data section at address
3242 @code{0x4000000}, and the bss section follows the data section.
3245 To let @code{@value{LD}} know which data changes when the sections are
3246 relocated, and how to change that data, @command{@value{AS}} also writes to the
3247 object file details of the relocation needed. To perform relocation
3248 @code{@value{LD}} must know, each time an address in the object
3252 Where in the object file is the beginning of this reference to
3255 How long (in bytes) is this reference?
3257 Which section does the address refer to? What is the numeric value of
3259 (@var{address}) @minus{} (@var{start-address of section})?
3262 Is the reference to an address ``Program-Counter relative''?
3265 @cindex addresses, format of
3266 @cindex section-relative addressing
3267 In fact, every address @command{@value{AS}} ever uses is expressed as
3269 (@var{section}) + (@var{offset into section})
3272 Further, most expressions @command{@value{AS}} computes have this section-relative
3275 (For some object formats, such as SOM for the HPPA, some expressions are
3276 symbol-relative instead.)
3279 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
3280 @var{N} into section @var{secname}.''
3282 Apart from text, data and bss sections you need to know about the
3283 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
3284 addresses in the absolute section remain unchanged. For example, address
3285 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
3286 @code{@value{LD}}. Although the linker never arranges two partial programs'
3287 data sections with overlapping addresses after linking, @emph{by definition}
3288 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
3289 part of a program is always the same address when the program is running as
3290 address @code{@{absolute@ 239@}} in any other part of the program.
3292 The idea of sections is extended to the @dfn{undefined} section. Any
3293 address whose section is unknown at assembly time is by definition
3294 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
3295 Since numbers are always defined, the only way to generate an undefined
3296 address is to mention an undefined symbol. A reference to a named
3297 common block would be such a symbol: its value is unknown at assembly
3298 time so it has section @emph{undefined}.
3300 By analogy the word @emph{section} is used to describe groups of sections in
3301 the linked program. @code{@value{LD}} puts all partial programs' text
3302 sections in contiguous addresses in the linked program. It is
3303 customary to refer to the @emph{text section} of a program, meaning all
3304 the addresses of all partial programs' text sections. Likewise for
3305 data and bss sections.
3307 Some sections are manipulated by @code{@value{LD}}; others are invented for
3308 use of @command{@value{AS}} and have no meaning except during assembly.
3311 @section Linker Sections
3312 @code{@value{LD}} deals with just four kinds of sections, summarized below.
3317 @cindex named sections
3318 @cindex sections, named
3319 @item named sections
3322 @cindex text section
3323 @cindex data section
3327 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
3328 separate but equal sections. Anything you can say of one section is
3331 When the program is running, however, it is
3332 customary for the text section to be unalterable. The
3333 text section is often shared among processes: it contains
3334 instructions, constants and the like. The data section of a running
3335 program is usually alterable: for example, C variables would be stored
3336 in the data section.
3341 This section contains zeroed bytes when your program begins running. It
3342 is used to hold uninitialized variables or common storage. The length of
3343 each partial program's bss section is important, but because it starts
3344 out containing zeroed bytes there is no need to store explicit zero
3345 bytes in the object file. The bss section was invented to eliminate
3346 those explicit zeros from object files.
3348 @cindex absolute section
3349 @item absolute section
3350 Address 0 of this section is always ``relocated'' to runtime address 0.
3351 This is useful if you want to refer to an address that @code{@value{LD}} must
3352 not change when relocating. In this sense we speak of absolute
3353 addresses being ``unrelocatable'': they do not change during relocation.
3355 @cindex undefined section
3356 @item undefined section
3357 This ``section'' is a catch-all for address references to objects not in
3358 the preceding sections.
3359 @c FIXME: ref to some other doc on obj-file formats could go here.
3362 @cindex relocation example
3363 An idealized example of three relocatable sections follows.
3365 The example uses the traditional section names @samp{.text} and @samp{.data}.
3367 Memory addresses are on the horizontal axis.
3371 @c END TEXI2ROFF-KILL
3374 partial program # 1: |ttttt|dddd|00|
3381 partial program # 2: |TTT|DDD|000|
3384 +--+---+-----+--+----+---+-----+~~
3385 linked program: | |TTT|ttttt| |dddd|DDD|00000|
3386 +--+---+-----+--+----+---+-----+~~
3388 addresses: 0 @dots{}
3395 \line{\it Partial program \#1: \hfil}
3396 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3397 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
3399 \line{\it Partial program \#2: \hfil}
3400 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3401 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
3403 \line{\it linked program: \hfil}
3404 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
3405 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
3406 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
3407 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
3409 \line{\it addresses: \hfil}
3413 @c END TEXI2ROFF-KILL
3416 @section Assembler Internal Sections
3418 @cindex internal assembler sections
3419 @cindex sections in messages, internal
3420 These sections are meant only for the internal use of @command{@value{AS}}. They
3421 have no meaning at run-time. You do not really need to know about these
3422 sections for most purposes; but they can be mentioned in @command{@value{AS}}
3423 warning messages, so it might be helpful to have an idea of their
3424 meanings to @command{@value{AS}}. These sections are used to permit the
3425 value of every expression in your assembly language program to be a
3426 section-relative address.
3429 @cindex assembler internal logic error
3430 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
3431 An internal assembler logic error has been found. This means there is a
3432 bug in the assembler.
3434 @cindex expr (internal section)
3436 The assembler stores complex expression internally as combinations of
3437 symbols. When it needs to represent an expression as a symbol, it puts
3438 it in the expr section.
3440 @c FIXME item transfer[t] vector preload
3441 @c FIXME item transfer[t] vector postload
3442 @c FIXME item register
3446 @section Sub-Sections
3448 @cindex numbered subsections
3449 @cindex grouping data
3455 fall into two sections: text and data.
3457 You may have separate groups of
3459 data in named sections
3463 data in named sections
3469 that you want to end up near to each other in the object file, even though they
3470 are not contiguous in the assembler source. @command{@value{AS}} allows you to
3471 use @dfn{subsections} for this purpose. Within each section, there can be
3472 numbered subsections with values from 0 to 8192. Objects assembled into the
3473 same subsection go into the object file together with other objects in the same
3474 subsection. For example, a compiler might want to store constants in the text
3475 section, but might not want to have them interspersed with the program being
3476 assembled. In this case, the compiler could issue a @samp{.text 0} before each
3477 section of code being output, and a @samp{.text 1} before each group of
3478 constants being output.
3480 Subsections are optional. If you do not use subsections, everything
3481 goes in subsection number zero.
3484 Each subsection is zero-padded up to a multiple of four bytes.
3485 (Subsections may be padded a different amount on different flavors
3486 of @command{@value{AS}}.)
3490 On the H8/300 platform, each subsection is zero-padded to a word
3491 boundary (two bytes).
3492 The same is true on the Renesas SH.
3495 @c FIXME section padding (alignment)?
3496 @c Rich Pixley says padding here depends on target obj code format; that
3497 @c doesn't seem particularly useful to say without further elaboration,
3498 @c so for now I say nothing about it. If this is a generic BFD issue,
3499 @c these paragraphs might need to vanish from this manual, and be
3500 @c discussed in BFD chapter of binutils (or some such).
3504 Subsections appear in your object file in numeric order, lowest numbered
3505 to highest. (All this to be compatible with other people's assemblers.)
3506 The object file contains no representation of subsections; @code{@value{LD}} and
3507 other programs that manipulate object files see no trace of them.
3508 They just see all your text subsections as a text section, and all your
3509 data subsections as a data section.
3511 To specify which subsection you want subsequent statements assembled
3512 into, use a numeric argument to specify it, in a @samp{.text
3513 @var{expression}} or a @samp{.data @var{expression}} statement.
3516 When generating COFF output, you
3521 can also use an extra subsection
3522 argument with arbitrary named sections: @samp{.section @var{name},
3527 When generating ELF output, you
3532 can also use the @code{.subsection} directive (@pxref{SubSection})
3533 to specify a subsection: @samp{.subsection @var{expression}}.
3535 @var{Expression} should be an absolute expression
3536 (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0}
3537 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3538 begins in @code{text 0}. For instance:
3540 .text 0 # The default subsection is text 0 anyway.
3541 .ascii "This lives in the first text subsection. *"
3543 .ascii "But this lives in the second text subsection."
3545 .ascii "This lives in the data section,"
3546 .ascii "in the first data subsection."
3548 .ascii "This lives in the first text section,"
3549 .ascii "immediately following the asterisk (*)."
3552 Each section has a @dfn{location counter} incremented by one for every byte
3553 assembled into that section. Because subsections are merely a convenience
3554 restricted to @command{@value{AS}} there is no concept of a subsection location
3555 counter. There is no way to directly manipulate a location counter---but the
3556 @code{.align} directive changes it, and any label definition captures its
3557 current value. The location counter of the section where statements are being
3558 assembled is said to be the @dfn{active} location counter.
3561 @section bss Section
3564 @cindex common variable storage
3565 The bss section is used for local common variable storage.
3566 You may allocate address space in the bss section, but you may
3567 not dictate data to load into it before your program executes. When
3568 your program starts running, all the contents of the bss
3569 section are zeroed bytes.
3571 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3572 @ref{Lcomm,,@code{.lcomm}}.
3574 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3575 another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}.
3578 When assembling for a target which supports multiple sections, such as ELF or
3579 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3580 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3581 section. Typically the section will only contain symbol definitions and
3582 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3589 Symbols are a central concept: the programmer uses symbols to name
3590 things, the linker uses symbols to link, and the debugger uses symbols
3594 @cindex debuggers, and symbol order
3595 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3596 the same order they were declared. This may break some debuggers.
3601 * Setting Symbols:: Giving Symbols Other Values
3602 * Symbol Names:: Symbol Names
3603 * Dot:: The Special Dot Symbol
3604 * Symbol Attributes:: Symbol Attributes
3611 A @dfn{label} is written as a symbol immediately followed by a colon
3612 @samp{:}. The symbol then represents the current value of the
3613 active location counter, and is, for example, a suitable instruction
3614 operand. You are warned if you use the same symbol to represent two
3615 different locations: the first definition overrides any other
3619 On the HPPA, the usual form for a label need not be immediately followed by a
3620 colon, but instead must start in column zero. Only one label may be defined on
3621 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3622 provides a special directive @code{.label} for defining labels more flexibly.
3625 @node Setting Symbols
3626 @section Giving Symbols Other Values
3628 @cindex assigning values to symbols
3629 @cindex symbol values, assigning
3630 A symbol can be given an arbitrary value by writing a symbol, followed
3631 by an equals sign @samp{=}, followed by an expression
3632 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3633 directive. @xref{Set,,@code{.set}}. In the same way, using a double
3634 equals sign @samp{=}@samp{=} here represents an equivalent of the
3635 @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}.
3638 Blackfin does not support symbol assignment with @samp{=}.
3642 @section Symbol Names
3644 @cindex symbol names
3645 @cindex names, symbol
3646 @ifclear SPECIAL-SYMS
3647 Symbol names begin with a letter or with one of @samp{._}. On most
3648 machines, you can also use @code{$} in symbol names; exceptions are
3649 noted in @ref{Machine Dependencies}. That character may be followed by any
3650 string of digits, letters, dollar signs (unless otherwise noted for a
3651 particular target machine), and underscores.
3655 Symbol names begin with a letter or with one of @samp{._}. On the
3656 Renesas SH you can also use @code{$} in symbol names. That
3657 character may be followed by any string of digits, letters, dollar signs (save
3658 on the H8/300), and underscores.
3662 Case of letters is significant: @code{foo} is a different symbol name
3665 Symbol names do not start with a digit. An exception to this rule is made for
3666 Local Labels. See below.
3668 Multibyte characters are supported. To generate a symbol name containing
3669 multibyte characters enclose it within double quotes and use escape codes. cf
3670 @xref{Strings}. Generating a multibyte symbol name from a label is not
3671 currently supported.
3673 Each symbol has exactly one name. Each name in an assembly language program
3674 refers to exactly one symbol. You may use that symbol name any number of times
3677 @subheading Local Symbol Names
3679 @cindex local symbol names
3680 @cindex symbol names, local
3681 A local symbol is any symbol beginning with certain local label prefixes.
3682 By default, the local label prefix is @samp{.L} for ELF systems or
3683 @samp{L} for traditional a.out systems, but each target may have its own
3684 set of local label prefixes.
3686 On the HPPA local symbols begin with @samp{L$}.
3689 Local symbols are defined and used within the assembler, but they are
3690 normally not saved in object files. Thus, they are not visible when debugging.
3691 You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols})
3692 to retain the local symbols in the object files.
3694 @subheading Local Labels
3696 @cindex local labels
3697 @cindex temporary symbol names
3698 @cindex symbol names, temporary
3699 Local labels are different from local symbols. Local labels help compilers and
3700 programmers use names temporarily. They create symbols which are guaranteed to
3701 be unique over the entire scope of the input source code and which can be
3702 referred to by a simple notation. To define a local label, write a label of
3703 the form @samp{@b{N}:} (where @b{N} represents any positive integer). To refer
3704 to the most recent previous definition of that label write @samp{@b{N}b}, using
3705 the same number as when you defined the label. To refer to the next definition
3706 of a local label, write @samp{@b{N}f}---the @samp{b} stands for ``backwards''
3707 and the @samp{f} stands for ``forwards''.
3709 There is no restriction on how you can use these labels, and you can reuse them
3710 too. So that it is possible to repeatedly define the same local label (using
3711 the same number @samp{@b{N}}), although you can only refer to the most recently
3712 defined local label of that number (for a backwards reference) or the next
3713 definition of a specific local label for a forward reference. It is also worth
3714 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3715 implemented in a slightly more efficient manner than the others.
3726 Which is the equivalent of:
3729 label_1: branch label_3
3730 label_2: branch label_1
3731 label_3: branch label_4
3732 label_4: branch label_3
3735 Local label names are only a notational device. They are immediately
3736 transformed into more conventional symbol names before the assembler uses them.
3737 The symbol names are stored in the symbol table, appear in error messages, and
3738 are optionally emitted to the object file. The names are constructed using
3742 @item @emph{local label prefix}
3743 All local symbols begin with the system-specific local label prefix.
3744 Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols
3745 that start with the local label prefix. These labels are
3746 used for symbols you are never intended to see. If you use the
3747 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3748 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3749 you may use them in debugging.
3752 This is the number that was used in the local label definition. So if the
3753 label is written @samp{55:} then the number is @samp{55}.
3756 This unusual character is included so you do not accidentally invent a symbol
3757 of the same name. The character has ASCII value of @samp{\002} (control-B).
3759 @item @emph{ordinal number}
3760 This is a serial number to keep the labels distinct. The first definition of
3761 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3762 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3763 the number @samp{1} and its 15th definition gets @samp{15} as well.
3766 So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and
3767 the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}.
3769 @subheading Dollar Local Labels
3770 @cindex dollar local symbols
3772 On some targets @code{@value{AS}} also supports an even more local form of
3773 local labels called dollar labels. These labels go out of scope (i.e., they
3774 become undefined) as soon as a non-local label is defined. Thus they remain
3775 valid for only a small region of the input source code. Normal local labels,
3776 by contrast, remain in scope for the entire file, or until they are redefined
3777 by another occurrence of the same local label.
3779 Dollar labels are defined in exactly the same way as ordinary local labels,
3780 except that they have a dollar sign suffix to their numeric value, e.g.,
3783 They can also be distinguished from ordinary local labels by their transformed
3784 names which use ASCII character @samp{\001} (control-A) as the magic character
3785 to distinguish them from ordinary labels. For example, the fifth definition of
3786 @samp{6$} may be named @samp{.L6@kbd{C-A}5}.
3789 @section The Special Dot Symbol
3791 @cindex dot (symbol)
3792 @cindex @code{.} (symbol)
3793 @cindex current address
3794 @cindex location counter
3795 The special symbol @samp{.} refers to the current address that
3796 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3797 .long .} defines @code{melvin} to contain its own address.
3798 Assigning a value to @code{.} is treated the same as a @code{.org}
3800 @ifclear no-space-dir
3801 Thus, the expression @samp{.=.+4} is the same as saying
3805 @node Symbol Attributes
3806 @section Symbol Attributes
3808 @cindex symbol attributes
3809 @cindex attributes, symbol
3810 Every symbol has, as well as its name, the attributes ``Value'' and
3811 ``Type''. Depending on output format, symbols can also have auxiliary
3814 The detailed definitions are in @file{a.out.h}.
3817 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3818 all these attributes, and probably won't warn you. This makes the
3819 symbol an externally defined symbol, which is generally what you
3823 * Symbol Value:: Value
3824 * Symbol Type:: Type
3827 * a.out Symbols:: Symbol Attributes: @code{a.out}
3831 * a.out Symbols:: Symbol Attributes: @code{a.out}
3834 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3839 * COFF Symbols:: Symbol Attributes for COFF
3842 * SOM Symbols:: Symbol Attributes for SOM
3849 @cindex value of a symbol
3850 @cindex symbol value
3851 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3852 location in the text, data, bss or absolute sections the value is the
3853 number of addresses from the start of that section to the label.
3854 Naturally for text, data and bss sections the value of a symbol changes
3855 as @code{@value{LD}} changes section base addresses during linking. Absolute
3856 symbols' values do not change during linking: that is why they are
3859 The value of an undefined symbol is treated in a special way. If it is
3860 0 then the symbol is not defined in this assembler source file, and
3861 @code{@value{LD}} tries to determine its value from other files linked into the
3862 same program. You make this kind of symbol simply by mentioning a symbol
3863 name without defining it. A non-zero value represents a @code{.comm}
3864 common declaration. The value is how much common storage to reserve, in
3865 bytes (addresses). The symbol refers to the first address of the
3871 @cindex type of a symbol
3873 The type attribute of a symbol contains relocation (section)
3874 information, any flag settings indicating that a symbol is external, and
3875 (optionally), other information for linkers and debuggers. The exact
3876 format depends on the object-code output format in use.
3881 @c The following avoids a "widow" subsection title. @group would be
3882 @c better if it were available outside examples.
3885 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3887 @cindex @code{b.out} symbol attributes
3888 @cindex symbol attributes, @code{b.out}
3889 These symbol attributes appear only when @command{@value{AS}} is configured for
3890 one of the Berkeley-descended object output formats---@code{a.out} or
3896 @subsection Symbol Attributes: @code{a.out}
3898 @cindex @code{a.out} symbol attributes
3899 @cindex symbol attributes, @code{a.out}
3905 @subsection Symbol Attributes: @code{a.out}
3907 @cindex @code{a.out} symbol attributes
3908 @cindex symbol attributes, @code{a.out}
3912 * Symbol Desc:: Descriptor
3913 * Symbol Other:: Other
3917 @subsubsection Descriptor
3919 @cindex descriptor, of @code{a.out} symbol
3920 This is an arbitrary 16-bit value. You may establish a symbol's
3921 descriptor value by using a @code{.desc} statement
3922 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3923 @command{@value{AS}}.
3926 @subsubsection Other
3928 @cindex other attribute, of @code{a.out} symbol
3929 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3934 @subsection Symbol Attributes for COFF
3936 @cindex COFF symbol attributes
3937 @cindex symbol attributes, COFF
3939 The COFF format supports a multitude of auxiliary symbol attributes;
3940 like the primary symbol attributes, they are set between @code{.def} and
3941 @code{.endef} directives.
3943 @subsubsection Primary Attributes
3945 @cindex primary attributes, COFF symbols
3946 The symbol name is set with @code{.def}; the value and type,
3947 respectively, with @code{.val} and @code{.type}.
3949 @subsubsection Auxiliary Attributes
3951 @cindex auxiliary attributes, COFF symbols
3952 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3953 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3954 table information for COFF.
3959 @subsection Symbol Attributes for SOM
3961 @cindex SOM symbol attributes
3962 @cindex symbol attributes, SOM
3964 The SOM format for the HPPA supports a multitude of symbol attributes set with
3965 the @code{.EXPORT} and @code{.IMPORT} directives.
3967 The attributes are described in @cite{HP9000 Series 800 Assembly
3968 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3969 @code{EXPORT} assembler directive documentation.
3973 @chapter Expressions
3977 @cindex numeric values
3978 An @dfn{expression} specifies an address or numeric value.
3979 Whitespace may precede and/or follow an expression.
3981 The result of an expression must be an absolute number, or else an offset into
3982 a particular section. If an expression is not absolute, and there is not
3983 enough information when @command{@value{AS}} sees the expression to know its
3984 section, a second pass over the source program might be necessary to interpret
3985 the expression---but the second pass is currently not implemented.
3986 @command{@value{AS}} aborts with an error message in this situation.
3989 * Empty Exprs:: Empty Expressions
3990 * Integer Exprs:: Integer Expressions
3994 @section Empty Expressions
3996 @cindex empty expressions
3997 @cindex expressions, empty
3998 An empty expression has no value: it is just whitespace or null.
3999 Wherever an absolute expression is required, you may omit the
4000 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
4001 is compatible with other assemblers.
4004 @section Integer Expressions
4006 @cindex integer expressions
4007 @cindex expressions, integer
4008 An @dfn{integer expression} is one or more @emph{arguments} delimited
4009 by @emph{operators}.
4012 * Arguments:: Arguments
4013 * Operators:: Operators
4014 * Prefix Ops:: Prefix Operators
4015 * Infix Ops:: Infix Operators
4019 @subsection Arguments
4021 @cindex expression arguments
4022 @cindex arguments in expressions
4023 @cindex operands in expressions
4024 @cindex arithmetic operands
4025 @dfn{Arguments} are symbols, numbers or subexpressions. In other
4026 contexts arguments are sometimes called ``arithmetic operands''. In
4027 this manual, to avoid confusing them with the ``instruction operands'' of
4028 the machine language, we use the term ``argument'' to refer to parts of
4029 expressions only, reserving the word ``operand'' to refer only to machine
4030 instruction operands.
4032 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
4033 @var{section} is one of text, data, bss, absolute,
4034 or undefined. @var{NNN} is a signed, 2's complement 32 bit
4037 Numbers are usually integers.
4039 A number can be a flonum or bignum. In this case, you are warned
4040 that only the low order 32 bits are used, and @command{@value{AS}} pretends
4041 these 32 bits are an integer. You may write integer-manipulating
4042 instructions that act on exotic constants, compatible with other
4045 @cindex subexpressions
4046 Subexpressions are a left parenthesis @samp{(} followed by an integer
4047 expression, followed by a right parenthesis @samp{)}; or a prefix
4048 operator followed by an argument.
4051 @subsection Operators
4053 @cindex operators, in expressions
4054 @cindex arithmetic functions
4055 @cindex functions, in expressions
4056 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
4057 operators are followed by an argument. Infix operators appear
4058 between their arguments. Operators may be preceded and/or followed by
4062 @subsection Prefix Operator
4064 @cindex prefix operators
4065 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
4066 one argument, which must be absolute.
4068 @c the tex/end tex stuff surrounding this small table is meant to make
4069 @c it align, on the printed page, with the similar table in the next
4070 @c section (which is inside an enumerate).
4072 \global\advance\leftskip by \itemindent
4077 @dfn{Negation}. Two's complement negation.
4079 @dfn{Complementation}. Bitwise not.
4083 \global\advance\leftskip by -\itemindent
4087 @subsection Infix Operators
4089 @cindex infix operators
4090 @cindex operators, permitted arguments
4091 @dfn{Infix operators} take two arguments, one on either side. Operators
4092 have precedence, but operations with equal precedence are performed left
4093 to right. Apart from @code{+} or @option{-}, both arguments must be
4094 absolute, and the result is absolute.
4097 @cindex operator precedence
4098 @cindex precedence of operators
4105 @dfn{Multiplication}.
4108 @dfn{Division}. Truncation is the same as the C operator @samp{/}
4114 @dfn{Shift Left}. Same as the C operator @samp{<<}.
4117 @dfn{Shift Right}. Same as the C operator @samp{>>}.
4121 Intermediate precedence
4126 @dfn{Bitwise Inclusive Or}.
4132 @dfn{Bitwise Exclusive Or}.
4135 @dfn{Bitwise Or Not}.
4142 @cindex addition, permitted arguments
4143 @cindex plus, permitted arguments
4144 @cindex arguments for addition
4146 @dfn{Addition}. If either argument is absolute, the result has the section of
4147 the other argument. You may not add together arguments from different
4150 @cindex subtraction, permitted arguments
4151 @cindex minus, permitted arguments
4152 @cindex arguments for subtraction
4154 @dfn{Subtraction}. If the right argument is absolute, the
4155 result has the section of the left argument.
4156 If both arguments are in the same section, the result is absolute.
4157 You may not subtract arguments from different sections.
4158 @c FIXME is there still something useful to say about undefined - undefined ?
4160 @cindex comparison expressions
4161 @cindex expressions, comparison
4166 @dfn{Is Not Equal To}
4170 @dfn{Is Greater Than}
4172 @dfn{Is Greater Than Or Equal To}
4174 @dfn{Is Less Than Or Equal To}
4176 The comparison operators can be used as infix operators. A true results has a
4177 value of -1 whereas a false result has a value of 0. Note, these operators
4178 perform signed comparisons.
4181 @item Lowest Precedence
4190 These two logical operations can be used to combine the results of sub
4191 expressions. Note, unlike the comparison operators a true result returns a
4192 value of 1 but a false results does still return 0. Also note that the logical
4193 or operator has a slightly lower precedence than logical and.
4198 In short, it's only meaningful to add or subtract the @emph{offsets} in an
4199 address; you can only have a defined section in one of the two arguments.
4202 @chapter Assembler Directives
4204 @cindex directives, machine independent
4205 @cindex pseudo-ops, machine independent
4206 @cindex machine independent directives
4207 All assembler directives have names that begin with a period (@samp{.}).
4208 The rest of the name is letters, usually in lower case.
4210 This chapter discusses directives that are available regardless of the
4211 target machine configuration for the @sc{gnu} assembler.
4213 Some machine configurations provide additional directives.
4214 @xref{Machine Dependencies}.
4217 @ifset machine-directives
4218 @xref{Machine Dependencies}, for additional directives.
4223 * Abort:: @code{.abort}
4225 * ABORT (COFF):: @code{.ABORT}
4228 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
4229 * Altmacro:: @code{.altmacro}
4230 * Ascii:: @code{.ascii "@var{string}"}@dots{}
4231 * Asciz:: @code{.asciz "@var{string}"}@dots{}
4232 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
4233 * Bundle directives:: @code{.bundle_align_mode @var{abs-expr}}, etc
4234 * Byte:: @code{.byte @var{expressions}}
4235 * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
4236 * Comm:: @code{.comm @var{symbol} , @var{length} }
4237 * Data:: @code{.data @var{subsection}}
4239 * Def:: @code{.def @var{name}}
4242 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
4248 * Double:: @code{.double @var{flonums}}
4249 * Eject:: @code{.eject}
4250 * Else:: @code{.else}
4251 * Elseif:: @code{.elseif}
4254 * Endef:: @code{.endef}
4257 * Endfunc:: @code{.endfunc}
4258 * Endif:: @code{.endif}
4259 * Equ:: @code{.equ @var{symbol}, @var{expression}}
4260 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
4261 * Eqv:: @code{.eqv @var{symbol}, @var{expression}}
4263 * Error:: @code{.error @var{string}}
4264 * Exitm:: @code{.exitm}
4265 * Extern:: @code{.extern}
4266 * Fail:: @code{.fail}
4267 * File:: @code{.file}
4268 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
4269 * Float:: @code{.float @var{flonums}}
4270 * Func:: @code{.func}
4271 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4273 * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
4274 * Hidden:: @code{.hidden @var{names}}
4277 * hword:: @code{.hword @var{expressions}}
4278 * Ident:: @code{.ident}
4279 * If:: @code{.if @var{absolute expression}}
4280 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4281 * Include:: @code{.include "@var{file}"}
4282 * Int:: @code{.int @var{expressions}}
4284 * Internal:: @code{.internal @var{names}}
4287 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
4288 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
4289 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
4290 * Lflags:: @code{.lflags}
4291 @ifclear no-line-dir
4292 * Line:: @code{.line @var{line-number}}
4295 * Linkonce:: @code{.linkonce [@var{type}]}
4296 * List:: @code{.list}
4297 * Ln:: @code{.ln @var{line-number}}
4298 * Loc:: @code{.loc @var{fileno} @var{lineno}}
4299 * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}}
4301 * Local:: @code{.local @var{names}}
4304 * Long:: @code{.long @var{expressions}}
4306 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
4309 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
4310 * MRI:: @code{.mri @var{val}}
4311 * Noaltmacro:: @code{.noaltmacro}
4312 * Nolist:: @code{.nolist}
4313 * Octa:: @code{.octa @var{bignums}}
4314 * Offset:: @code{.offset @var{loc}}
4315 * Org:: @code{.org @var{new-lc}, @var{fill}}
4316 * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4318 * PopSection:: @code{.popsection}
4319 * Previous:: @code{.previous}
4322 * Print:: @code{.print @var{string}}
4324 * Protected:: @code{.protected @var{names}}
4327 * Psize:: @code{.psize @var{lines}, @var{columns}}
4328 * Purgem:: @code{.purgem @var{name}}
4330 * PushSection:: @code{.pushsection @var{name}}
4333 * Quad:: @code{.quad @var{bignums}}
4334 * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
4335 * Rept:: @code{.rept @var{count}}
4336 * Sbttl:: @code{.sbttl "@var{subheading}"}
4338 * Scl:: @code{.scl @var{class}}
4341 * Section:: @code{.section @var{name}[, @var{flags}]}
4344 * Set:: @code{.set @var{symbol}, @var{expression}}
4345 * Short:: @code{.short @var{expressions}}
4346 * Single:: @code{.single @var{flonums}}
4348 * Size:: @code{.size [@var{name} , @var{expression}]}
4350 @ifclear no-space-dir
4351 * Skip:: @code{.skip @var{size} , @var{fill}}
4354 * Sleb128:: @code{.sleb128 @var{expressions}}
4355 @ifclear no-space-dir
4356 * Space:: @code{.space @var{size} , @var{fill}}
4359 * Stab:: @code{.stabd, .stabn, .stabs}
4362 * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
4363 * Struct:: @code{.struct @var{expression}}
4365 * SubSection:: @code{.subsection}
4366 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
4370 * Tag:: @code{.tag @var{structname}}
4373 * Text:: @code{.text @var{subsection}}
4374 * Title:: @code{.title "@var{heading}"}
4376 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
4379 * Uleb128:: @code{.uleb128 @var{expressions}}
4381 * Val:: @code{.val @var{addr}}
4385 * Version:: @code{.version "@var{string}"}
4386 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
4387 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
4390 * Warning:: @code{.warning @var{string}}
4391 * Weak:: @code{.weak @var{names}}
4392 * Weakref:: @code{.weakref @var{alias}, @var{symbol}}
4393 * Word:: @code{.word @var{expressions}}
4394 @ifclear no-space-dir
4395 * Zero:: @code{.zero @var{size}}
4397 * Deprecated:: Deprecated Directives
4401 @section @code{.abort}
4403 @cindex @code{abort} directive
4404 @cindex stopping the assembly
4405 This directive stops the assembly immediately. It is for
4406 compatibility with other assemblers. The original idea was that the
4407 assembly language source would be piped into the assembler. If the sender
4408 of the source quit, it could use this directive tells @command{@value{AS}} to
4409 quit also. One day @code{.abort} will not be supported.
4413 @section @code{.ABORT} (COFF)
4415 @cindex @code{ABORT} directive
4416 When producing COFF output, @command{@value{AS}} accepts this directive as a
4417 synonym for @samp{.abort}.
4420 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
4426 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4428 @cindex padding the location counter
4429 @cindex @code{align} directive
4430 Pad the location counter (in the current subsection) to a particular storage
4431 boundary. The first expression (which must be absolute) is the alignment
4432 required, as described below.
4434 The second expression (also absolute) gives the fill value to be stored in the
4435 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4436 padding bytes are normally zero. However, on some systems, if the section is
4437 marked as containing code and the fill value is omitted, the space is filled
4438 with no-op instructions.
4440 The third expression is also absolute, and is also optional. If it is present,
4441 it is the maximum number of bytes that should be skipped by this alignment
4442 directive. If doing the alignment would require skipping more bytes than the
4443 specified maximum, then the alignment is not done at all. You can omit the
4444 fill value (the second argument) entirely by simply using two commas after the
4445 required alignment; this can be useful if you want the alignment to be filled
4446 with no-op instructions when appropriate.
4448 The way the required alignment is specified varies from system to system.
4449 For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or1k,
4450 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
4451 alignment request in bytes. For example @samp{.align 8} advances
4452 the location counter until it is a multiple of 8. If the location counter
4453 is already a multiple of 8, no change is needed. For the tic54x, the
4454 first expression is the alignment request in words.
4456 For other systems, including ppc, i386 using a.out format, arm and
4457 strongarm, it is the
4458 number of low-order zero bits the location counter must have after
4459 advancement. For example @samp{.align 3} advances the location
4460 counter until it a multiple of 8. If the location counter is already a
4461 multiple of 8, no change is needed.
4463 This inconsistency is due to the different behaviors of the various
4464 native assemblers for these systems which GAS must emulate.
4465 GAS also provides @code{.balign} and @code{.p2align} directives,
4466 described later, which have a consistent behavior across all
4467 architectures (but are specific to GAS).
4470 @section @code{.altmacro}
4471 Enable alternate macro mode, enabling:
4474 @item LOCAL @var{name} [ , @dots{} ]
4475 One additional directive, @code{LOCAL}, is available. It is used to
4476 generate a string replacement for each of the @var{name} arguments, and
4477 replace any instances of @var{name} in each macro expansion. The
4478 replacement string is unique in the assembly, and different for each
4479 separate macro expansion. @code{LOCAL} allows you to write macros that
4480 define symbols, without fear of conflict between separate macro expansions.
4482 @item String delimiters
4483 You can write strings delimited in these other ways besides
4484 @code{"@var{string}"}:
4487 @item '@var{string}'
4488 You can delimit strings with single-quote characters.
4490 @item <@var{string}>
4491 You can delimit strings with matching angle brackets.
4494 @item single-character string escape
4495 To include any single character literally in a string (even if the
4496 character would otherwise have some special meaning), you can prefix the
4497 character with @samp{!} (an exclamation mark). For example, you can
4498 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4500 @item Expression results as strings
4501 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4502 and use the result as a string.
4506 @section @code{.ascii "@var{string}"}@dots{}
4508 @cindex @code{ascii} directive
4509 @cindex string literals
4510 @code{.ascii} expects zero or more string literals (@pxref{Strings})
4511 separated by commas. It assembles each string (with no automatic
4512 trailing zero byte) into consecutive addresses.
4515 @section @code{.asciz "@var{string}"}@dots{}
4517 @cindex @code{asciz} directive
4518 @cindex zero-terminated strings
4519 @cindex null-terminated strings
4520 @code{.asciz} is just like @code{.ascii}, but each string is followed by
4521 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
4524 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4526 @cindex padding the location counter given number of bytes
4527 @cindex @code{balign} directive
4528 Pad the location counter (in the current subsection) to a particular
4529 storage boundary. The first expression (which must be absolute) is the
4530 alignment request in bytes. For example @samp{.balign 8} advances
4531 the location counter until it is a multiple of 8. If the location counter
4532 is already a multiple of 8, no change is needed.
4534 The second expression (also absolute) gives the fill value to be stored in the
4535 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4536 padding bytes are normally zero. However, on some systems, if the section is
4537 marked as containing code and the fill value is omitted, the space is filled
4538 with no-op instructions.
4540 The third expression is also absolute, and is also optional. If it is present,
4541 it is the maximum number of bytes that should be skipped by this alignment
4542 directive. If doing the alignment would require skipping more bytes than the
4543 specified maximum, then the alignment is not done at all. You can omit the
4544 fill value (the second argument) entirely by simply using two commas after the
4545 required alignment; this can be useful if you want the alignment to be filled
4546 with no-op instructions when appropriate.
4548 @cindex @code{balignw} directive
4549 @cindex @code{balignl} directive
4550 The @code{.balignw} and @code{.balignl} directives are variants of the
4551 @code{.balign} directive. The @code{.balignw} directive treats the fill
4552 pattern as a two byte word value. The @code{.balignl} directives treats the
4553 fill pattern as a four byte longword value. For example, @code{.balignw
4554 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4555 filled in with the value 0x368d (the exact placement of the bytes depends upon
4556 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4559 @node Bundle directives
4560 @section Bundle directives
4561 @subsection @code{.bundle_align_mode @var{abs-expr}}
4562 @cindex @code{bundle_align_mode} directive
4564 @cindex instruction bundle
4565 @cindex aligned instruction bundle
4566 @code{.bundle_align_mode} enables or disables @dfn{aligned instruction
4567 bundle} mode. In this mode, sequences of adjacent instructions are grouped
4568 into fixed-sized @dfn{bundles}. If the argument is zero, this mode is
4569 disabled (which is the default state). If the argument it not zero, it
4570 gives the size of an instruction bundle as a power of two (as for the
4571 @code{.p2align} directive, @pxref{P2align}).
4573 For some targets, it's an ABI requirement that no instruction may span a
4574 certain aligned boundary. A @dfn{bundle} is simply a sequence of
4575 instructions that starts on an aligned boundary. For example, if
4576 @var{abs-expr} is @code{5} then the bundle size is 32, so each aligned
4577 chunk of 32 bytes is a bundle. When aligned instruction bundle mode is in
4578 effect, no single instruction may span a boundary between bundles. If an
4579 instruction would start too close to the end of a bundle for the length of
4580 that particular instruction to fit within the bundle, then the space at the
4581 end of that bundle is filled with no-op instructions so the instruction
4582 starts in the next bundle. As a corollary, it's an error if any single
4583 instruction's encoding is longer than the bundle size.
4585 @subsection @code{.bundle_lock} and @code{.bundle_unlock}
4586 @cindex @code{bundle_lock} directive
4587 @cindex @code{bundle_unlock} directive
4588 The @code{.bundle_lock} and directive @code{.bundle_unlock} directives
4589 allow explicit control over instruction bundle padding. These directives
4590 are only valid when @code{.bundle_align_mode} has been used to enable
4591 aligned instruction bundle mode. It's an error if they appear when
4592 @code{.bundle_align_mode} has not been used at all, or when the last
4593 directive was @w{@code{.bundle_align_mode 0}}.
4595 @cindex bundle-locked
4596 For some targets, it's an ABI requirement that certain instructions may
4597 appear only as part of specified permissible sequences of multiple
4598 instructions, all within the same bundle. A pair of @code{.bundle_lock}
4599 and @code{.bundle_unlock} directives define a @dfn{bundle-locked}
4600 instruction sequence. For purposes of aligned instruction bundle mode, a
4601 sequence starting with @code{.bundle_lock} and ending with
4602 @code{.bundle_unlock} is treated as a single instruction. That is, the
4603 entire sequence must fit into a single bundle and may not span a bundle
4604 boundary. If necessary, no-op instructions will be inserted before the
4605 first instruction of the sequence so that the whole sequence starts on an
4606 aligned bundle boundary. It's an error if the sequence is longer than the
4609 For convenience when using @code{.bundle_lock} and @code{.bundle_unlock}
4610 inside assembler macros (@pxref{Macro}), bundle-locked sequences may be
4611 nested. That is, a second @code{.bundle_lock} directive before the next
4612 @code{.bundle_unlock} directive has no effect except that it must be
4613 matched by another closing @code{.bundle_unlock} so that there is the
4614 same number of @code{.bundle_lock} and @code{.bundle_unlock} directives.
4617 @section @code{.byte @var{expressions}}
4619 @cindex @code{byte} directive
4620 @cindex integers, one byte
4621 @code{.byte} expects zero or more expressions, separated by commas.
4622 Each expression is assembled into the next byte.
4624 @node CFI directives
4625 @section CFI directives
4626 @subsection @code{.cfi_sections @var{section_list}}
4627 @cindex @code{cfi_sections} directive
4628 @code{.cfi_sections} may be used to specify whether CFI directives
4629 should emit @code{.eh_frame} section and/or @code{.debug_frame} section.
4630 If @var{section_list} is @code{.eh_frame}, @code{.eh_frame} is emitted,
4631 if @var{section_list} is @code{.debug_frame}, @code{.debug_frame} is emitted.
4632 To emit both use @code{.eh_frame, .debug_frame}. The default if this
4633 directive is not used is @code{.cfi_sections .eh_frame}.
4635 On targets that support compact unwinding tables these can be generated
4636 by specifying @code{.eh_frame_entry} instead of @code{.eh_frame}.
4638 @subsection @code{.cfi_startproc [simple]}
4639 @cindex @code{cfi_startproc} directive
4640 @code{.cfi_startproc} is used at the beginning of each function that
4641 should have an entry in @code{.eh_frame}. It initializes some internal
4642 data structures. Don't forget to close the function by
4643 @code{.cfi_endproc}.
4645 Unless @code{.cfi_startproc} is used along with parameter @code{simple}
4646 it also emits some architecture dependent initial CFI instructions.
4648 @subsection @code{.cfi_endproc}
4649 @cindex @code{cfi_endproc} directive
4650 @code{.cfi_endproc} is used at the end of a function where it closes its
4651 unwind entry previously opened by
4652 @code{.cfi_startproc}, and emits it to @code{.eh_frame}.
4654 @subsection @code{.cfi_personality @var{encoding} [, @var{exp}]}
4655 @cindex @code{cfi_personality} directive
4656 @code{.cfi_personality} defines personality routine and its encoding.
4657 @var{encoding} must be a constant determining how the personality
4658 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4659 argument is not present, otherwise second argument should be
4660 a constant or a symbol name. When using indirect encodings,
4661 the symbol provided should be the location where personality
4662 can be loaded from, not the personality routine itself.
4663 The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff},
4664 no personality routine.
4666 @subsection @code{.cfi_personality_id @var{id}}
4667 @cindex @code{cfi_personality_id} directive
4668 @code{cfi_personality_id} defines a personality routine by its index as
4669 defined in a compact unwinding format.
4670 Only valid when generating compact EH frames (i.e.
4671 with @code{.cfi_sections eh_frame_entry}.
4673 @subsection @code{.cfi_fde_data [@var{opcode1} [, @dots{}]]}
4674 @cindex @code{cfi_fde_data} directive
4675 @code{cfi_fde_data} is used to describe the compact unwind opcodes to be
4676 used for the current function. These are emitted inline in the
4677 @code{.eh_frame_entry} section if small enough and there is no LSDA, or
4678 in the @code{.gnu.extab} section otherwise.
4679 Only valid when generating compact EH frames (i.e.
4680 with @code{.cfi_sections eh_frame_entry}.
4682 @subsection @code{.cfi_lsda @var{encoding} [, @var{exp}]}
4683 @code{.cfi_lsda} defines LSDA and its encoding.
4684 @var{encoding} must be a constant determining how the LSDA
4685 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), the second
4686 argument is not present, otherwise the second argument should be a constant
4687 or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff},
4688 meaning that no LSDA is present.
4690 @subsection @code{.cfi_inline_lsda} [@var{align}]
4691 @code{.cfi_inline_lsda} marks the start of a LSDA data section and
4692 switches to the corresponding @code{.gnu.extab} section.
4693 Must be preceded by a CFI block containing a @code{.cfi_lsda} directive.
4694 Only valid when generating compact EH frames (i.e.
4695 with @code{.cfi_sections eh_frame_entry}.
4697 The table header and unwinding opcodes will be generated at this point,
4698 so that they are immediately followed by the LSDA data. The symbol
4699 referenced by the @code{.cfi_lsda} directive should still be defined
4700 in case a fallback FDE based encoding is used. The LSDA data is terminated
4701 by a section directive.
4703 The optional @var{align} argument specifies the alignment required.
4704 The alignment is specified as a power of two, as with the
4705 @code{.p2align} directive.
4707 @subsection @code{.cfi_def_cfa @var{register}, @var{offset}}
4708 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4709 address from @var{register} and add @var{offset} to it}.
4711 @subsection @code{.cfi_def_cfa_register @var{register}}
4712 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4713 now on @var{register} will be used instead of the old one. Offset
4716 @subsection @code{.cfi_def_cfa_offset @var{offset}}
4717 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4718 remains the same, but @var{offset} is new. Note that it is the
4719 absolute offset that will be added to a defined register to compute
4722 @subsection @code{.cfi_adjust_cfa_offset @var{offset}}
4723 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4724 value that is added/substracted from the previous offset.
4726 @subsection @code{.cfi_offset @var{register}, @var{offset}}
4727 Previous value of @var{register} is saved at offset @var{offset} from
4730 @subsection @code{.cfi_rel_offset @var{register}, @var{offset}}
4731 Previous value of @var{register} is saved at offset @var{offset} from
4732 the current CFA register. This is transformed to @code{.cfi_offset}
4733 using the known displacement of the CFA register from the CFA.
4734 This is often easier to use, because the number will match the
4735 code it's annotating.
4737 @subsection @code{.cfi_register @var{register1}, @var{register2}}
4738 Previous value of @var{register1} is saved in register @var{register2}.
4740 @subsection @code{.cfi_restore @var{register}}
4741 @code{.cfi_restore} says that the rule for @var{register} is now the
4742 same as it was at the beginning of the function, after all initial
4743 instruction added by @code{.cfi_startproc} were executed.
4745 @subsection @code{.cfi_undefined @var{register}}
4746 From now on the previous value of @var{register} can't be restored anymore.
4748 @subsection @code{.cfi_same_value @var{register}}
4749 Current value of @var{register} is the same like in the previous frame,
4750 i.e. no restoration needed.
4752 @subsection @code{.cfi_remember_state},
4753 First save all current rules for all registers by @code{.cfi_remember_state},
4754 then totally screw them up by subsequent @code{.cfi_*} directives and when
4755 everything is hopelessly bad, use @code{.cfi_restore_state} to restore
4756 the previous saved state.
4758 @subsection @code{.cfi_return_column @var{register}}
4759 Change return column @var{register}, i.e. the return address is either
4760 directly in @var{register} or can be accessed by rules for @var{register}.
4762 @subsection @code{.cfi_signal_frame}
4763 Mark current function as signal trampoline.
4765 @subsection @code{.cfi_window_save}
4766 SPARC register window has been saved.
4768 @subsection @code{.cfi_escape} @var{expression}[, @dots{}]
4769 Allows the user to add arbitrary bytes to the unwind info. One
4770 might use this to add OS-specific CFI opcodes, or generic CFI
4771 opcodes that GAS does not yet support.
4773 @subsection @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}}
4774 The current value of @var{register} is @var{label}. The value of @var{label}
4775 will be encoded in the output file according to @var{encoding}; see the
4776 description of @code{.cfi_personality} for details on this encoding.
4778 The usefulness of equating a register to a fixed label is probably
4779 limited to the return address register. Here, it can be useful to
4780 mark a code segment that has only one return address which is reached
4781 by a direct branch and no copy of the return address exists in memory
4782 or another register.
4785 @section @code{.comm @var{symbol} , @var{length} }
4787 @cindex @code{comm} directive
4788 @cindex symbol, common
4789 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
4790 common symbol in one object file may be merged with a defined or common symbol
4791 of the same name in another object file. If @code{@value{LD}} does not see a
4792 definition for the symbol--just one or more common symbols--then it will
4793 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
4794 absolute expression. If @code{@value{LD}} sees multiple common symbols with
4795 the same name, and they do not all have the same size, it will allocate space
4796 using the largest size.
4799 When using ELF or (as a GNU extension) PE, the @code{.comm} directive takes
4800 an optional third argument. This is the desired alignment of the symbol,
4801 specified for ELF as a byte boundary (for example, an alignment of 16 means
4802 that the least significant 4 bits of the address should be zero), and for PE
4803 as a power of two (for example, an alignment of 5 means aligned to a 32-byte
4804 boundary). The alignment must be an absolute expression, and it must be a
4805 power of two. If @code{@value{LD}} allocates uninitialized memory for the
4806 common symbol, it will use the alignment when placing the symbol. If no
4807 alignment is specified, @command{@value{AS}} will set the alignment to the
4808 largest power of two less than or equal to the size of the symbol, up to a
4809 maximum of 16 on ELF, or the default section alignment of 4 on PE@footnote{This
4810 is not the same as the executable image file alignment controlled by @code{@value{LD}}'s
4811 @samp{--section-alignment} option; image file sections in PE are aligned to
4812 multiples of 4096, which is far too large an alignment for ordinary variables.
4813 It is rather the default alignment for (non-debug) sections within object
4814 (@samp{*.o}) files, which are less strictly aligned.}.
4818 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4819 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4823 @section @code{.data @var{subsection}}
4825 @cindex @code{data} directive
4826 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4827 end of the data subsection numbered @var{subsection} (which is an
4828 absolute expression). If @var{subsection} is omitted, it defaults
4833 @section @code{.def @var{name}}
4835 @cindex @code{def} directive
4836 @cindex COFF symbols, debugging
4837 @cindex debugging COFF symbols
4838 Begin defining debugging information for a symbol @var{name}; the
4839 definition extends until the @code{.endef} directive is encountered.
4842 This directive is only observed when @command{@value{AS}} is configured for COFF
4843 format output; when producing @code{b.out}, @samp{.def} is recognized,
4850 @section @code{.desc @var{symbol}, @var{abs-expression}}
4852 @cindex @code{desc} directive
4853 @cindex COFF symbol descriptor
4854 @cindex symbol descriptor, COFF
4855 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4856 to the low 16 bits of an absolute expression.
4859 The @samp{.desc} directive is not available when @command{@value{AS}} is
4860 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4861 object format. For the sake of compatibility, @command{@value{AS}} accepts
4862 it, but produces no output, when configured for COFF.
4868 @section @code{.dim}
4870 @cindex @code{dim} directive
4871 @cindex COFF auxiliary symbol information
4872 @cindex auxiliary symbol information, COFF
4873 This directive is generated by compilers to include auxiliary debugging
4874 information in the symbol table. It is only permitted inside
4875 @code{.def}/@code{.endef} pairs.
4878 @samp{.dim} is only meaningful when generating COFF format output; when
4879 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4885 @section @code{.double @var{flonums}}
4887 @cindex @code{double} directive
4888 @cindex floating point numbers (double)
4889 @code{.double} expects zero or more flonums, separated by commas. It
4890 assembles floating point numbers.
4892 The exact kind of floating point numbers emitted depends on how
4893 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4897 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4898 in @sc{ieee} format.
4903 @section @code{.eject}
4905 @cindex @code{eject} directive
4906 @cindex new page, in listings
4907 @cindex page, in listings
4908 @cindex listing control: new page
4909 Force a page break at this point, when generating assembly listings.
4912 @section @code{.else}
4914 @cindex @code{else} directive
4915 @code{.else} is part of the @command{@value{AS}} support for conditional
4916 assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section
4917 of code to be assembled if the condition for the preceding @code{.if}
4921 @section @code{.elseif}
4923 @cindex @code{elseif} directive
4924 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4925 assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new
4926 @code{.if} block that would otherwise fill the entire @code{.else} section.
4929 @section @code{.end}
4931 @cindex @code{end} directive
4932 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4933 process anything in the file past the @code{.end} directive.
4937 @section @code{.endef}
4939 @cindex @code{endef} directive
4940 This directive flags the end of a symbol definition begun with
4944 @samp{.endef} is only meaningful when generating COFF format output; if
4945 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4946 directive but ignores it.
4951 @section @code{.endfunc}
4952 @cindex @code{endfunc} directive
4953 @code{.endfunc} marks the end of a function specified with @code{.func}.
4956 @section @code{.endif}
4958 @cindex @code{endif} directive
4959 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4960 it marks the end of a block of code that is only assembled
4961 conditionally. @xref{If,,@code{.if}}.
4964 @section @code{.equ @var{symbol}, @var{expression}}
4966 @cindex @code{equ} directive
4967 @cindex assigning values to symbols
4968 @cindex symbols, assigning values to
4969 This directive sets the value of @var{symbol} to @var{expression}.
4970 It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}.
4973 The syntax for @code{equ} on the HPPA is
4974 @samp{@var{symbol} .equ @var{expression}}.
4978 The syntax for @code{equ} on the Z80 is
4979 @samp{@var{symbol} equ @var{expression}}.
4980 On the Z80 it is an eror if @var{symbol} is already defined,
4981 but the symbol is not protected from later redefinition.
4982 Compare @ref{Equiv}.
4986 @section @code{.equiv @var{symbol}, @var{expression}}
4987 @cindex @code{equiv} directive
4988 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4989 the assembler will signal an error if @var{symbol} is already defined. Note a
4990 symbol which has been referenced but not actually defined is considered to be
4993 Except for the contents of the error message, this is roughly equivalent to
5000 plus it protects the symbol from later redefinition.
5003 @section @code{.eqv @var{symbol}, @var{expression}}
5004 @cindex @code{eqv} directive
5005 The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to
5006 evaluate the expression or any part of it immediately. Instead each time
5007 the resulting symbol is used in an expression, a snapshot of its current
5011 @section @code{.err}
5012 @cindex @code{err} directive
5013 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
5014 message and, unless the @option{-Z} option was used, it will not generate an
5015 object file. This can be used to signal an error in conditionally compiled code.
5018 @section @code{.error "@var{string}"}
5019 @cindex error directive
5021 Similarly to @code{.err}, this directive emits an error, but you can specify a
5022 string that will be emitted as the error message. If you don't specify the
5023 message, it defaults to @code{".error directive invoked in source file"}.
5024 @xref{Errors, ,Error and Warning Messages}.
5027 .error "This code has not been assembled and tested."
5031 @section @code{.exitm}
5032 Exit early from the current macro definition. @xref{Macro}.
5035 @section @code{.extern}
5037 @cindex @code{extern} directive
5038 @code{.extern} is accepted in the source program---for compatibility
5039 with other assemblers---but it is ignored. @command{@value{AS}} treats
5040 all undefined symbols as external.
5043 @section @code{.fail @var{expression}}
5045 @cindex @code{fail} directive
5046 Generates an error or a warning. If the value of the @var{expression} is 500
5047 or more, @command{@value{AS}} will print a warning message. If the value is less
5048 than 500, @command{@value{AS}} will print an error message. The message will
5049 include the value of @var{expression}. This can occasionally be useful inside
5050 complex nested macros or conditional assembly.
5053 @section @code{.file}
5054 @cindex @code{file} directive
5056 @ifclear no-file-dir
5057 There are two different versions of the @code{.file} directive. Targets
5058 that support DWARF2 line number information use the DWARF2 version of
5059 @code{.file}. Other targets use the default version.
5061 @subheading Default Version
5063 @cindex logical file name
5064 @cindex file name, logical
5065 This version of the @code{.file} directive tells @command{@value{AS}} that we
5066 are about to start a new logical file. The syntax is:
5072 @var{string} is the new file name. In general, the filename is
5073 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
5074 to specify an empty file name, you must give the quotes--@code{""}. This
5075 statement may go away in future: it is only recognized to be compatible with
5076 old @command{@value{AS}} programs.
5078 @subheading DWARF2 Version
5081 When emitting DWARF2 line number information, @code{.file} assigns filenames
5082 to the @code{.debug_line} file name table. The syntax is:
5085 .file @var{fileno} @var{filename}
5088 The @var{fileno} operand should be a unique positive integer to use as the
5089 index of the entry in the table. The @var{filename} operand is a C string
5092 The detail of filename indices is exposed to the user because the filename
5093 table is shared with the @code{.debug_info} section of the DWARF2 debugging
5094 information, and thus the user must know the exact indices that table
5098 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
5100 @cindex @code{fill} directive
5101 @cindex writing patterns in memory
5102 @cindex patterns, writing in memory
5103 @var{repeat}, @var{size} and @var{value} are absolute expressions.
5104 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
5105 may be zero or more. @var{Size} may be zero or more, but if it is
5106 more than 8, then it is deemed to have the value 8, compatible with
5107 other people's assemblers. The contents of each @var{repeat} bytes
5108 is taken from an 8-byte number. The highest order 4 bytes are
5109 zero. The lowest order 4 bytes are @var{value} rendered in the
5110 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
5111 Each @var{size} bytes in a repetition is taken from the lowest order
5112 @var{size} bytes of this number. Again, this bizarre behavior is
5113 compatible with other people's assemblers.
5115 @var{size} and @var{value} are optional.
5116 If the second comma and @var{value} are absent, @var{value} is
5117 assumed zero. If the first comma and following tokens are absent,
5118 @var{size} is assumed to be 1.
5121 @section @code{.float @var{flonums}}
5123 @cindex floating point numbers (single)
5124 @cindex @code{float} directive
5125 This directive assembles zero or more flonums, separated by commas. It
5126 has the same effect as @code{.single}.
5128 The exact kind of floating point numbers emitted depends on how
5129 @command{@value{AS}} is configured.
5130 @xref{Machine Dependencies}.
5134 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
5135 in @sc{ieee} format.
5140 @section @code{.func @var{name}[,@var{label}]}
5141 @cindex @code{func} directive
5142 @code{.func} emits debugging information to denote function @var{name}, and
5143 is ignored unless the file is assembled with debugging enabled.
5144 Only @samp{--gstabs[+]} is currently supported.
5145 @var{label} is the entry point of the function and if omitted @var{name}
5146 prepended with the @samp{leading char} is used.
5147 @samp{leading char} is usually @code{_} or nothing, depending on the target.
5148 All functions are currently defined to have @code{void} return type.
5149 The function must be terminated with @code{.endfunc}.
5152 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
5154 @cindex @code{global} directive
5155 @cindex symbol, making visible to linker
5156 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
5157 @var{symbol} in your partial program, its value is made available to
5158 other partial programs that are linked with it. Otherwise,
5159 @var{symbol} takes its attributes from a symbol of the same name
5160 from another file linked into the same program.
5162 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
5163 compatibility with other assemblers.
5166 On the HPPA, @code{.global} is not always enough to make it accessible to other
5167 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
5168 @xref{HPPA Directives, ,HPPA Assembler Directives}.
5173 @section @code{.gnu_attribute @var{tag},@var{value}}
5174 Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
5177 @section @code{.hidden @var{names}}
5179 @cindex @code{hidden} directive
5181 This is one of the ELF visibility directives. The other two are
5182 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
5183 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5185 This directive overrides the named symbols default visibility (which is set by
5186 their binding: local, global or weak). The directive sets the visibility to
5187 @code{hidden} which means that the symbols are not visible to other components.
5188 Such symbols are always considered to be @code{protected} as well.
5192 @section @code{.hword @var{expressions}}
5194 @cindex @code{hword} directive
5195 @cindex integers, 16-bit
5196 @cindex numbers, 16-bit
5197 @cindex sixteen bit integers
5198 This expects zero or more @var{expressions}, and emits
5199 a 16 bit number for each.
5202 This directive is a synonym for @samp{.short}; depending on the target
5203 architecture, it may also be a synonym for @samp{.word}.
5207 This directive is a synonym for @samp{.short}.
5210 This directive is a synonym for both @samp{.short} and @samp{.word}.
5215 @section @code{.ident}
5217 @cindex @code{ident} directive
5219 This directive is used by some assemblers to place tags in object files. The
5220 behavior of this directive varies depending on the target. When using the
5221 a.out object file format, @command{@value{AS}} simply accepts the directive for
5222 source-file compatibility with existing assemblers, but does not emit anything
5223 for it. When using COFF, comments are emitted to the @code{.comment} or
5224 @code{.rdata} section, depending on the target. When using ELF, comments are
5225 emitted to the @code{.comment} section.
5228 @section @code{.if @var{absolute expression}}
5230 @cindex conditional assembly
5231 @cindex @code{if} directive
5232 @code{.if} marks the beginning of a section of code which is only
5233 considered part of the source program being assembled if the argument
5234 (which must be an @var{absolute expression}) is non-zero. The end of
5235 the conditional section of code must be marked by @code{.endif}
5236 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
5237 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
5238 If you have several conditions to check, @code{.elseif} may be used to avoid
5239 nesting blocks if/else within each subsequent @code{.else} block.
5241 The following variants of @code{.if} are also supported:
5243 @cindex @code{ifdef} directive
5244 @item .ifdef @var{symbol}
5245 Assembles the following section of code if the specified @var{symbol}
5246 has been defined. Note a symbol which has been referenced but not yet defined
5247 is considered to be undefined.
5249 @cindex @code{ifb} directive
5250 @item .ifb @var{text}
5251 Assembles the following section of code if the operand is blank (empty).
5253 @cindex @code{ifc} directive
5254 @item .ifc @var{string1},@var{string2}
5255 Assembles the following section of code if the two strings are the same. The
5256 strings may be optionally quoted with single quotes. If they are not quoted,
5257 the first string stops at the first comma, and the second string stops at the
5258 end of the line. Strings which contain whitespace should be quoted. The
5259 string comparison is case sensitive.
5261 @cindex @code{ifeq} directive
5262 @item .ifeq @var{absolute expression}
5263 Assembles the following section of code if the argument is zero.
5265 @cindex @code{ifeqs} directive
5266 @item .ifeqs @var{string1},@var{string2}
5267 Another form of @code{.ifc}. The strings must be quoted using double quotes.
5269 @cindex @code{ifge} directive
5270 @item .ifge @var{absolute expression}
5271 Assembles the following section of code if the argument is greater than or
5274 @cindex @code{ifgt} directive
5275 @item .ifgt @var{absolute expression}
5276 Assembles the following section of code if the argument is greater than zero.
5278 @cindex @code{ifle} directive
5279 @item .ifle @var{absolute expression}
5280 Assembles the following section of code if the argument is less than or equal
5283 @cindex @code{iflt} directive
5284 @item .iflt @var{absolute expression}
5285 Assembles the following section of code if the argument is less than zero.
5287 @cindex @code{ifnb} directive
5288 @item .ifnb @var{text}
5289 Like @code{.ifb}, but the sense of the test is reversed: this assembles the
5290 following section of code if the operand is non-blank (non-empty).
5292 @cindex @code{ifnc} directive
5293 @item .ifnc @var{string1},@var{string2}.
5294 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
5295 following section of code if the two strings are not the same.
5297 @cindex @code{ifndef} directive
5298 @cindex @code{ifnotdef} directive
5299 @item .ifndef @var{symbol}
5300 @itemx .ifnotdef @var{symbol}
5301 Assembles the following section of code if the specified @var{symbol}
5302 has not been defined. Both spelling variants are equivalent. Note a symbol
5303 which has been referenced but not yet defined is considered to be undefined.
5305 @cindex @code{ifne} directive
5306 @item .ifne @var{absolute expression}
5307 Assembles the following section of code if the argument is not equal to zero
5308 (in other words, this is equivalent to @code{.if}).
5310 @cindex @code{ifnes} directive
5311 @item .ifnes @var{string1},@var{string2}
5312 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
5313 following section of code if the two strings are not the same.
5317 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
5319 @cindex @code{incbin} directive
5320 @cindex binary files, including
5321 The @code{incbin} directive includes @var{file} verbatim at the current
5322 location. You can control the search paths used with the @samp{-I} command-line
5323 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5326 The @var{skip} argument skips a number of bytes from the start of the
5327 @var{file}. The @var{count} argument indicates the maximum number of bytes to
5328 read. Note that the data is not aligned in any way, so it is the user's
5329 responsibility to make sure that proper alignment is provided both before and
5330 after the @code{incbin} directive.
5333 @section @code{.include "@var{file}"}
5335 @cindex @code{include} directive
5336 @cindex supporting files, including
5337 @cindex files, including
5338 This directive provides a way to include supporting files at specified
5339 points in your source program. The code from @var{file} is assembled as
5340 if it followed the point of the @code{.include}; when the end of the
5341 included file is reached, assembly of the original file continues. You
5342 can control the search paths used with the @samp{-I} command-line option
5343 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5347 @section @code{.int @var{expressions}}
5349 @cindex @code{int} directive
5350 @cindex integers, 32-bit
5351 Expect zero or more @var{expressions}, of any section, separated by commas.
5352 For each expression, emit a number that, at run time, is the value of that
5353 expression. The byte order and bit size of the number depends on what kind
5354 of target the assembly is for.
5358 On most forms of the H8/300, @code{.int} emits 16-bit
5359 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
5366 @section @code{.internal @var{names}}
5368 @cindex @code{internal} directive
5370 This is one of the ELF visibility directives. The other two are
5371 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
5372 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5374 This directive overrides the named symbols default visibility (which is set by
5375 their binding: local, global or weak). The directive sets the visibility to
5376 @code{internal} which means that the symbols are considered to be @code{hidden}
5377 (i.e., not visible to other components), and that some extra, processor specific
5378 processing must also be performed upon the symbols as well.
5382 @section @code{.irp @var{symbol},@var{values}}@dots{}
5384 @cindex @code{irp} directive
5385 Evaluate a sequence of statements assigning different values to @var{symbol}.
5386 The sequence of statements starts at the @code{.irp} directive, and is
5387 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
5388 set to @var{value}, and the sequence of statements is assembled. If no
5389 @var{value} is listed, the sequence of statements is assembled once, with
5390 @var{symbol} set to the null string. To refer to @var{symbol} within the
5391 sequence of statements, use @var{\symbol}.
5393 For example, assembling
5401 is equivalent to assembling
5409 For some caveats with the spelling of @var{symbol}, see also @ref{Macro}.
5412 @section @code{.irpc @var{symbol},@var{values}}@dots{}
5414 @cindex @code{irpc} directive
5415 Evaluate a sequence of statements assigning different values to @var{symbol}.
5416 The sequence of statements starts at the @code{.irpc} directive, and is
5417 terminated by an @code{.endr} directive. For each character in @var{value},
5418 @var{symbol} is set to the character, and the sequence of statements is
5419 assembled. If no @var{value} is listed, the sequence of statements is
5420 assembled once, with @var{symbol} set to the null string. To refer to
5421 @var{symbol} within the sequence of statements, use @var{\symbol}.
5423 For example, assembling
5431 is equivalent to assembling
5439 For some caveats with the spelling of @var{symbol}, see also the discussion
5443 @section @code{.lcomm @var{symbol} , @var{length}}
5445 @cindex @code{lcomm} directive
5446 @cindex local common symbols
5447 @cindex symbols, local common
5448 Reserve @var{length} (an absolute expression) bytes for a local common
5449 denoted by @var{symbol}. The section and value of @var{symbol} are
5450 those of the new local common. The addresses are allocated in the bss
5451 section, so that at run-time the bytes start off zeroed. @var{Symbol}
5452 is not declared global (@pxref{Global,,@code{.global}}), so is normally
5453 not visible to @code{@value{LD}}.
5456 Some targets permit a third argument to be used with @code{.lcomm}. This
5457 argument specifies the desired alignment of the symbol in the bss section.
5461 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
5462 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
5466 @section @code{.lflags}
5468 @cindex @code{lflags} directive (ignored)
5469 @command{@value{AS}} accepts this directive, for compatibility with other
5470 assemblers, but ignores it.
5472 @ifclear no-line-dir
5474 @section @code{.line @var{line-number}}
5476 @cindex @code{line} directive
5477 @cindex logical line number
5479 Change the logical line number. @var{line-number} must be an absolute
5480 expression. The next line has that logical line number. Therefore any other
5481 statements on the current line (after a statement separator character) are
5482 reported as on logical line number @var{line-number} @minus{} 1. One day
5483 @command{@value{AS}} will no longer support this directive: it is recognized only
5484 for compatibility with existing assembler programs.
5487 Even though this is a directive associated with the @code{a.out} or
5488 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
5489 when producing COFF output, and treats @samp{.line} as though it
5490 were the COFF @samp{.ln} @emph{if} it is found outside a
5491 @code{.def}/@code{.endef} pair.
5493 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
5494 used by compilers to generate auxiliary symbol information for
5499 @section @code{.linkonce [@var{type}]}
5501 @cindex @code{linkonce} directive
5502 @cindex common sections
5503 Mark the current section so that the linker only includes a single copy of it.
5504 This may be used to include the same section in several different object files,
5505 but ensure that the linker will only include it once in the final output file.
5506 The @code{.linkonce} pseudo-op must be used for each instance of the section.
5507 Duplicate sections are detected based on the section name, so it should be
5510 This directive is only supported by a few object file formats; as of this
5511 writing, the only object file format which supports it is the Portable
5512 Executable format used on Windows NT.
5514 The @var{type} argument is optional. If specified, it must be one of the
5515 following strings. For example:
5519 Not all types may be supported on all object file formats.
5523 Silently discard duplicate sections. This is the default.
5526 Warn if there are duplicate sections, but still keep only one copy.
5529 Warn if any of the duplicates have different sizes.
5532 Warn if any of the duplicates do not have exactly the same contents.
5536 @section @code{.list}
5538 @cindex @code{list} directive
5539 @cindex listing control, turning on
5540 Control (in conjunction with the @code{.nolist} directive) whether or
5541 not assembly listings are generated. These two directives maintain an
5542 internal counter (which is zero initially). @code{.list} increments the
5543 counter, and @code{.nolist} decrements it. Assembly listings are
5544 generated whenever the counter is greater than zero.
5546 By default, listings are disabled. When you enable them (with the
5547 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
5548 the initial value of the listing counter is one.
5551 @section @code{.ln @var{line-number}}
5553 @cindex @code{ln} directive
5554 @ifclear no-line-dir
5555 @samp{.ln} is a synonym for @samp{.line}.
5558 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
5559 must be an absolute expression. The next line has that logical
5560 line number, so any other statements on the current line (after a
5561 statement separator character @code{;}) are reported as on logical
5562 line number @var{line-number} @minus{} 1.
5565 This directive is accepted, but ignored, when @command{@value{AS}} is
5566 configured for @code{b.out}; its effect is only associated with COFF
5572 @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]}
5573 @cindex @code{loc} directive
5574 When emitting DWARF2 line number information,
5575 the @code{.loc} directive will add a row to the @code{.debug_line} line
5576 number matrix corresponding to the immediately following assembly
5577 instruction. The @var{fileno}, @var{lineno}, and optional @var{column}
5578 arguments will be applied to the @code{.debug_line} state machine before
5581 The @var{options} are a sequence of the following tokens in any order:
5585 This option will set the @code{basic_block} register in the
5586 @code{.debug_line} state machine to @code{true}.
5589 This option will set the @code{prologue_end} register in the
5590 @code{.debug_line} state machine to @code{true}.
5592 @item epilogue_begin
5593 This option will set the @code{epilogue_begin} register in the
5594 @code{.debug_line} state machine to @code{true}.
5596 @item is_stmt @var{value}
5597 This option will set the @code{is_stmt} register in the
5598 @code{.debug_line} state machine to @code{value}, which must be
5601 @item isa @var{value}
5602 This directive will set the @code{isa} register in the @code{.debug_line}
5603 state machine to @var{value}, which must be an unsigned integer.
5605 @item discriminator @var{value}
5606 This directive will set the @code{discriminator} register in the @code{.debug_line}
5607 state machine to @var{value}, which must be an unsigned integer.
5611 @node Loc_mark_labels
5612 @section @code{.loc_mark_labels @var{enable}}
5613 @cindex @code{loc_mark_labels} directive
5614 When emitting DWARF2 line number information,
5615 the @code{.loc_mark_labels} directive makes the assembler emit an entry
5616 to the @code{.debug_line} line number matrix with the @code{basic_block}
5617 register in the state machine set whenever a code label is seen.
5618 The @var{enable} argument should be either 1 or 0, to enable or disable
5619 this function respectively.
5623 @section @code{.local @var{names}}
5625 @cindex @code{local} directive
5626 This directive, which is available for ELF targets, marks each symbol in
5627 the comma-separated list of @code{names} as a local symbol so that it
5628 will not be externally visible. If the symbols do not already exist,
5629 they will be created.
5631 For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not
5632 accept an alignment argument, which is the case for most ELF targets,
5633 the @code{.local} directive can be used in combination with @code{.comm}
5634 (@pxref{Comm}) to define aligned local common data.
5638 @section @code{.long @var{expressions}}
5640 @cindex @code{long} directive
5641 @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}.
5644 @c no one seems to know what this is for or whether this description is
5645 @c what it really ought to do
5647 @section @code{.lsym @var{symbol}, @var{expression}}
5649 @cindex @code{lsym} directive
5650 @cindex symbol, not referenced in assembly
5651 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
5652 the hash table, ensuring it cannot be referenced by name during the
5653 rest of the assembly. This sets the attributes of the symbol to be
5654 the same as the expression value:
5656 @var{other} = @var{descriptor} = 0
5657 @var{type} = @r{(section of @var{expression})}
5658 @var{value} = @var{expression}
5661 The new symbol is not flagged as external.
5665 @section @code{.macro}
5668 The commands @code{.macro} and @code{.endm} allow you to define macros that
5669 generate assembly output. For example, this definition specifies a macro
5670 @code{sum} that puts a sequence of numbers into memory:
5673 .macro sum from=0, to=5
5682 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
5694 @item .macro @var{macname}
5695 @itemx .macro @var{macname} @var{macargs} @dots{}
5696 @cindex @code{macro} directive
5697 Begin the definition of a macro called @var{macname}. If your macro
5698 definition requires arguments, specify their names after the macro name,
5699 separated by commas or spaces. You can qualify the macro argument to
5700 indicate whether all invocations must specify a non-blank value (through
5701 @samp{:@code{req}}), or whether it takes all of the remaining arguments
5702 (through @samp{:@code{vararg}}). You can supply a default value for any
5703 macro argument by following the name with @samp{=@var{deflt}}. You
5704 cannot define two macros with the same @var{macname} unless it has been
5705 subject to the @code{.purgem} directive (@pxref{Purgem}) between the two
5706 definitions. For example, these are all valid @code{.macro} statements:
5710 Begin the definition of a macro called @code{comm}, which takes no
5713 @item .macro plus1 p, p1
5714 @itemx .macro plus1 p p1
5715 Either statement begins the definition of a macro called @code{plus1},
5716 which takes two arguments; within the macro definition, write
5717 @samp{\p} or @samp{\p1} to evaluate the arguments.
5719 @item .macro reserve_str p1=0 p2
5720 Begin the definition of a macro called @code{reserve_str}, with two
5721 arguments. The first argument has a default value, but not the second.
5722 After the definition is complete, you can call the macro either as
5723 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
5724 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
5725 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
5726 @samp{0}, and @samp{\p2} evaluating to @var{b}).
5728 @item .macro m p1:req, p2=0, p3:vararg
5729 Begin the definition of a macro called @code{m}, with at least three
5730 arguments. The first argument must always have a value specified, but
5731 not the second, which instead has a default value. The third formal
5732 will get assigned all remaining arguments specified at invocation time.
5734 When you call a macro, you can specify the argument values either by
5735 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
5736 @samp{sum to=17, from=9}.
5740 Note that since each of the @var{macargs} can be an identifier exactly
5741 as any other one permitted by the target architecture, there may be
5742 occasional problems if the target hand-crafts special meanings to certain
5743 characters when they occur in a special position. For example, if the colon
5744 (@code{:}) is generally permitted to be part of a symbol name, but the
5745 architecture specific code special-cases it when occurring as the final
5746 character of a symbol (to denote a label), then the macro parameter
5747 replacement code will have no way of knowing that and consider the whole
5748 construct (including the colon) an identifier, and check only this
5749 identifier for being the subject to parameter substitution. So for example
5750 this macro definition:
5758 might not work as expected. Invoking @samp{label foo} might not create a label
5759 called @samp{foo} but instead just insert the text @samp{\l:} into the
5760 assembler source, probably generating an error about an unrecognised
5763 Similarly problems might occur with the period character (@samp{.})
5764 which is often allowed inside opcode names (and hence identifier names). So
5765 for example constructing a macro to build an opcode from a base name and a
5766 length specifier like this:
5769 .macro opcode base length
5774 and invoking it as @samp{opcode store l} will not create a @samp{store.l}
5775 instruction but instead generate some kind of error as the assembler tries to
5776 interpret the text @samp{\base.\length}.
5778 There are several possible ways around this problem:
5781 @item Insert white space
5782 If it is possible to use white space characters then this is the simplest
5791 @item Use @samp{\()}
5792 The string @samp{\()} can be used to separate the end of a macro argument from
5793 the following text. eg:
5796 .macro opcode base length
5801 @item Use the alternate macro syntax mode
5802 In the alternative macro syntax mode the ampersand character (@samp{&}) can be
5803 used as a separator. eg:
5813 Note: this problem of correctly identifying string parameters to pseudo ops
5814 also applies to the identifiers used in @code{.irp} (@pxref{Irp})
5815 and @code{.irpc} (@pxref{Irpc}) as well.
5818 @cindex @code{endm} directive
5819 Mark the end of a macro definition.
5822 @cindex @code{exitm} directive
5823 Exit early from the current macro definition.
5825 @cindex number of macros executed
5826 @cindex macros, count executed
5828 @command{@value{AS}} maintains a counter of how many macros it has
5829 executed in this pseudo-variable; you can copy that number to your
5830 output with @samp{\@@}, but @emph{only within a macro definition}.
5832 @item LOCAL @var{name} [ , @dots{} ]
5833 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
5834 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
5835 @xref{Altmacro,,@code{.altmacro}}.
5839 @section @code{.mri @var{val}}
5841 @cindex @code{mri} directive
5842 @cindex MRI mode, temporarily
5843 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
5844 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
5845 affects code assembled until the next @code{.mri} directive, or until the end
5846 of the file. @xref{M, MRI mode, MRI mode}.
5849 @section @code{.noaltmacro}
5850 Disable alternate macro mode. @xref{Altmacro}.
5853 @section @code{.nolist}
5855 @cindex @code{nolist} directive
5856 @cindex listing control, turning off
5857 Control (in conjunction with the @code{.list} directive) whether or
5858 not assembly listings are generated. These two directives maintain an
5859 internal counter (which is zero initially). @code{.list} increments the
5860 counter, and @code{.nolist} decrements it. Assembly listings are
5861 generated whenever the counter is greater than zero.
5864 @section @code{.octa @var{bignums}}
5866 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
5867 @cindex @code{octa} directive
5868 @cindex integer, 16-byte
5869 @cindex sixteen byte integer
5870 This directive expects zero or more bignums, separated by commas. For each
5871 bignum, it emits a 16-byte integer.
5873 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
5874 hence @emph{octa}-word for 16 bytes.
5877 @section @code{.offset @var{loc}}
5879 @cindex @code{offset} directive
5880 Set the location counter to @var{loc} in the absolute section. @var{loc} must
5881 be an absolute expression. This directive may be useful for defining
5882 symbols with absolute values. Do not confuse it with the @code{.org}
5886 @section @code{.org @var{new-lc} , @var{fill}}
5888 @cindex @code{org} directive
5889 @cindex location counter, advancing
5890 @cindex advancing location counter
5891 @cindex current address, advancing
5892 Advance the location counter of the current section to
5893 @var{new-lc}. @var{new-lc} is either an absolute expression or an
5894 expression with the same section as the current subsection. That is,
5895 you can't use @code{.org} to cross sections: if @var{new-lc} has the
5896 wrong section, the @code{.org} directive is ignored. To be compatible
5897 with former assemblers, if the section of @var{new-lc} is absolute,
5898 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
5899 is the same as the current subsection.
5901 @code{.org} may only increase the location counter, or leave it
5902 unchanged; you cannot use @code{.org} to move the location counter
5905 @c double negative used below "not undefined" because this is a specific
5906 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
5907 @c section. doc@cygnus.com 18feb91
5908 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
5909 may not be undefined. If you really detest this restriction we eagerly await
5910 a chance to share your improved assembler.
5912 Beware that the origin is relative to the start of the section, not
5913 to the start of the subsection. This is compatible with other
5914 people's assemblers.
5916 When the location counter (of the current subsection) is advanced, the
5917 intervening bytes are filled with @var{fill} which should be an
5918 absolute expression. If the comma and @var{fill} are omitted,
5919 @var{fill} defaults to zero.
5922 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
5924 @cindex padding the location counter given a power of two
5925 @cindex @code{p2align} directive
5926 Pad the location counter (in the current subsection) to a particular
5927 storage boundary. The first expression (which must be absolute) is the
5928 number of low-order zero bits the location counter must have after
5929 advancement. For example @samp{.p2align 3} advances the location
5930 counter until it a multiple of 8. If the location counter is already a
5931 multiple of 8, no change is needed.
5933 The second expression (also absolute) gives the fill value to be stored in the
5934 padding bytes. It (and the comma) may be omitted. If it is omitted, the
5935 padding bytes are normally zero. However, on some systems, if the section is
5936 marked as containing code and the fill value is omitted, the space is filled
5937 with no-op instructions.
5939 The third expression is also absolute, and is also optional. If it is present,
5940 it is the maximum number of bytes that should be skipped by this alignment
5941 directive. If doing the alignment would require skipping more bytes than the
5942 specified maximum, then the alignment is not done at all. You can omit the
5943 fill value (the second argument) entirely by simply using two commas after the
5944 required alignment; this can be useful if you want the alignment to be filled
5945 with no-op instructions when appropriate.
5947 @cindex @code{p2alignw} directive
5948 @cindex @code{p2alignl} directive
5949 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5950 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5951 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5952 fill pattern as a four byte longword value. For example, @code{.p2alignw
5953 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5954 filled in with the value 0x368d (the exact placement of the bytes depends upon
5955 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5960 @section @code{.popsection}
5962 @cindex @code{popsection} directive
5963 @cindex Section Stack
5964 This is one of the ELF section stack manipulation directives. The others are
5965 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5966 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5969 This directive replaces the current section (and subsection) with the top
5970 section (and subsection) on the section stack. This section is popped off the
5976 @section @code{.previous}
5978 @cindex @code{previous} directive
5979 @cindex Section Stack
5980 This is one of the ELF section stack manipulation directives. The others are
5981 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5982 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5983 (@pxref{PopSection}).
5985 This directive swaps the current section (and subsection) with most recently
5986 referenced section/subsection pair prior to this one. Multiple
5987 @code{.previous} directives in a row will flip between two sections (and their
5988 subsections). For example:
6000 Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
6006 # Now in section A subsection 1
6010 # Now in section B subsection 0
6013 # Now in section B subsection 1
6016 # Now in section B subsection 0
6020 Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
6021 section B and 0x9abc into subsection 1 of section B.
6023 In terms of the section stack, this directive swaps the current section with
6024 the top section on the section stack.
6028 @section @code{.print @var{string}}
6030 @cindex @code{print} directive
6031 @command{@value{AS}} will print @var{string} on the standard output during
6032 assembly. You must put @var{string} in double quotes.
6036 @section @code{.protected @var{names}}
6038 @cindex @code{protected} directive
6040 This is one of the ELF visibility directives. The other two are
6041 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
6043 This directive overrides the named symbols default visibility (which is set by
6044 their binding: local, global or weak). The directive sets the visibility to
6045 @code{protected} which means that any references to the symbols from within the
6046 components that defines them must be resolved to the definition in that
6047 component, even if a definition in another component would normally preempt
6052 @section @code{.psize @var{lines} , @var{columns}}
6054 @cindex @code{psize} directive
6055 @cindex listing control: paper size
6056 @cindex paper size, for listings
6057 Use this directive to declare the number of lines---and, optionally, the
6058 number of columns---to use for each page, when generating listings.
6060 If you do not use @code{.psize}, listings use a default line-count
6061 of 60. You may omit the comma and @var{columns} specification; the
6062 default width is 200 columns.
6064 @command{@value{AS}} generates formfeeds whenever the specified number of
6065 lines is exceeded (or whenever you explicitly request one, using
6068 If you specify @var{lines} as @code{0}, no formfeeds are generated save
6069 those explicitly specified with @code{.eject}.
6072 @section @code{.purgem @var{name}}
6074 @cindex @code{purgem} directive
6075 Undefine the macro @var{name}, so that later uses of the string will not be
6076 expanded. @xref{Macro}.
6080 @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]}
6082 @cindex @code{pushsection} directive
6083 @cindex Section Stack
6084 This is one of the ELF section stack manipulation directives. The others are
6085 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
6086 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6089 This directive pushes the current section (and subsection) onto the
6090 top of the section stack, and then replaces the current section and
6091 subsection with @code{name} and @code{subsection}. The optional
6092 @code{flags}, @code{type} and @code{arguments} are treated the same
6093 as in the @code{.section} (@pxref{Section}) directive.
6097 @section @code{.quad @var{bignums}}
6099 @cindex @code{quad} directive
6100 @code{.quad} expects zero or more bignums, separated by commas. For
6101 each bignum, it emits
6103 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
6104 warning message; and just takes the lowest order 8 bytes of the bignum.
6105 @cindex eight-byte integer
6106 @cindex integer, 8-byte
6108 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
6109 hence @emph{quad}-word for 8 bytes.
6112 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
6113 warning message; and just takes the lowest order 16 bytes of the bignum.
6114 @cindex sixteen-byte integer
6115 @cindex integer, 16-byte
6119 @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
6121 @cindex @code{reloc} directive
6122 Generate a relocation at @var{offset} of type @var{reloc_name} with value
6123 @var{expression}. If @var{offset} is a number, the relocation is generated in
6124 the current section. If @var{offset} is an expression that resolves to a
6125 symbol plus offset, the relocation is generated in the given symbol's section.
6126 @var{expression}, if present, must resolve to a symbol plus addend or to an
6127 absolute value, but note that not all targets support an addend. e.g. ELF REL
6128 targets such as i386 store an addend in the section contents rather than in the
6129 relocation. This low level interface does not support addends stored in the
6133 @section @code{.rept @var{count}}
6135 @cindex @code{rept} directive
6136 Repeat the sequence of lines between the @code{.rept} directive and the next
6137 @code{.endr} directive @var{count} times.
6139 For example, assembling
6147 is equivalent to assembling
6156 @section @code{.sbttl "@var{subheading}"}
6158 @cindex @code{sbttl} directive
6159 @cindex subtitles for listings
6160 @cindex listing control: subtitle
6161 Use @var{subheading} as the title (third line, immediately after the
6162 title line) when generating assembly listings.
6164 This directive affects subsequent pages, as well as the current page if
6165 it appears within ten lines of the top of a page.
6169 @section @code{.scl @var{class}}
6171 @cindex @code{scl} directive
6172 @cindex symbol storage class (COFF)
6173 @cindex COFF symbol storage class
6174 Set the storage-class value for a symbol. This directive may only be
6175 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
6176 whether a symbol is static or external, or it may record further
6177 symbolic debugging information.
6180 The @samp{.scl} directive is primarily associated with COFF output; when
6181 configured to generate @code{b.out} output format, @command{@value{AS}}
6182 accepts this directive but ignores it.
6188 @section @code{.section @var{name}}
6190 @cindex named section
6191 Use the @code{.section} directive to assemble the following code into a section
6194 This directive is only supported for targets that actually support arbitrarily
6195 named sections; on @code{a.out} targets, for example, it is not accepted, even
6196 with a standard @code{a.out} section name.
6200 @c only print the extra heading if both COFF and ELF are set
6201 @subheading COFF Version
6204 @cindex @code{section} directive (COFF version)
6205 For COFF targets, the @code{.section} directive is used in one of the following
6209 .section @var{name}[, "@var{flags}"]
6210 .section @var{name}[, @var{subsection}]
6213 If the optional argument is quoted, it is taken as flags to use for the
6214 section. Each flag is a single character. The following flags are recognized:
6217 bss section (uninitialized data)
6219 section is not loaded
6225 exclude section from linking
6231 shared section (meaningful for PE targets)
6233 ignored. (For compatibility with the ELF version)
6235 section is not readable (meaningful for PE targets)
6237 single-digit power-of-two section alignment (GNU extension)
6240 If no flags are specified, the default flags depend upon the section name. If
6241 the section name is not recognized, the default will be for the section to be
6242 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
6243 from the section, rather than adding them, so if they are used on their own it
6244 will be as if no flags had been specified at all.
6246 If the optional argument to the @code{.section} directive is not quoted, it is
6247 taken as a subsection number (@pxref{Sub-Sections}).
6252 @c only print the extra heading if both COFF and ELF are set
6253 @subheading ELF Version
6256 @cindex Section Stack
6257 This is one of the ELF section stack manipulation directives. The others are
6258 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
6259 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
6260 @code{.previous} (@pxref{Previous}).
6262 @cindex @code{section} directive (ELF version)
6263 For ELF targets, the @code{.section} directive is used like this:
6266 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]]
6269 @anchor{Section Name Substitutions}
6270 @kindex --sectname-subst
6271 @cindex section name substitution
6272 If the @samp{--sectname-subst} command-line option is provided, the @var{name}
6273 argument may contain a substitution sequence. Only @code{%S} is supported
6274 at the moment, and substitutes the current section name. For example:
6277 .macro exception_code
6278 .section %S.exception
6279 [exception code here]
6294 The two @code{exception_code} invocations above would create the
6295 @code{.text.exception} and @code{.init.exception} sections respectively.
6296 This is useful e.g. to discriminate between anciliary sections that are
6297 tied to setup code to be discarded after use from anciliary sections that
6298 need to stay resident without having to define multiple @code{exception_code}
6299 macros just for that purpose.
6301 The optional @var{flags} argument is a quoted string which may contain any
6302 combination of the following characters:
6305 section is allocatable
6307 section is excluded from executable and shared library.
6311 section is executable
6313 section is mergeable
6315 section contains zero terminated strings
6317 section is a member of a section group
6319 section is used for thread-local-storage
6321 section is a member of the previously-current section's group, if any
6324 The optional @var{type} argument may contain one of the following constants:
6327 section contains data
6329 section does not contain data (i.e., section only occupies space)
6331 section contains data which is used by things other than the program
6333 section contains an array of pointers to init functions
6335 section contains an array of pointers to finish functions
6336 @item @@preinit_array
6337 section contains an array of pointers to pre-init functions
6340 Many targets only support the first three section types.
6342 Note on targets where the @code{@@} character is the start of a comment (eg
6343 ARM) then another character is used instead. For example the ARM port uses the
6346 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
6347 be specified as well as an extra argument---@var{entsize}---like this:
6350 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
6353 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
6354 constants, each @var{entsize} octets long. Sections with both @code{M} and
6355 @code{S} must contain zero terminated strings where each character is
6356 @var{entsize} bytes long. The linker may remove duplicates within sections with
6357 the same name, same entity size and same flags. @var{entsize} must be an
6358 absolute expression. For sections with both @code{M} and @code{S}, a string
6359 which is a suffix of a larger string is considered a duplicate. Thus
6360 @code{"def"} will be merged with @code{"abcdef"}; A reference to the first
6361 @code{"def"} will be changed to a reference to @code{"abcdef"+3}.
6363 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
6364 be present along with an additional field like this:
6367 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
6370 The @var{GroupName} field specifies the name of the section group to which this
6371 particular section belongs. The optional linkage field can contain:
6374 indicates that only one copy of this section should be retained
6379 Note: if both the @var{M} and @var{G} flags are present then the fields for
6380 the Merge flag should come first, like this:
6383 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
6386 If @var{flags} contains the @code{?} symbol then it may not also contain the
6387 @code{G} symbol and the @var{GroupName} or @var{linkage} fields should not be
6388 present. Instead, @code{?} says to consider the section that's current before
6389 this directive. If that section used @code{G}, then the new section will use
6390 @code{G} with those same @var{GroupName} and @var{linkage} fields implicitly.
6391 If not, then the @code{?} symbol has no effect.
6393 If no flags are specified, the default flags depend upon the section name. If
6394 the section name is not recognized, the default will be for the section to have
6395 none of the above flags: it will not be allocated in memory, nor writable, nor
6396 executable. The section will contain data.
6398 For ELF targets, the assembler supports another type of @code{.section}
6399 directive for compatibility with the Solaris assembler:
6402 .section "@var{name}"[, @var{flags}...]
6405 Note that the section name is quoted. There may be a sequence of comma
6409 section is allocatable
6413 section is executable
6415 section is excluded from executable and shared library.
6417 section is used for thread local storage
6420 This directive replaces the current section and subsection. See the
6421 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
6422 some examples of how this directive and the other section stack directives
6428 @section @code{.set @var{symbol}, @var{expression}}
6430 @cindex @code{set} directive
6431 @cindex symbol value, setting
6432 Set the value of @var{symbol} to @var{expression}. This
6433 changes @var{symbol}'s value and type to conform to
6434 @var{expression}. If @var{symbol} was flagged as external, it remains
6435 flagged (@pxref{Symbol Attributes}).
6437 You may @code{.set} a symbol many times in the same assembly provided that the
6438 values given to the symbol are constants. Values that are based on expressions
6439 involving other symbols are allowed, but some targets may restrict this to only
6440 being done once per assembly. This is because those targets do not set the
6441 addresses of symbols at assembly time, but rather delay the assignment until a
6442 final link is performed. This allows the linker a chance to change the code in
6443 the files, changing the location of, and the relative distance between, various
6446 If you @code{.set} a global symbol, the value stored in the object
6447 file is the last value stored into it.
6450 On Z80 @code{set} is a real instruction, use
6451 @samp{@var{symbol} defl @var{expression}} instead.
6455 @section @code{.short @var{expressions}}
6457 @cindex @code{short} directive
6459 @code{.short} is normally the same as @samp{.word}.
6460 @xref{Word,,@code{.word}}.
6462 In some configurations, however, @code{.short} and @code{.word} generate
6463 numbers of different lengths. @xref{Machine Dependencies}.
6467 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
6470 This expects zero or more @var{expressions}, and emits
6471 a 16 bit number for each.
6476 @section @code{.single @var{flonums}}
6478 @cindex @code{single} directive
6479 @cindex floating point numbers (single)
6480 This directive assembles zero or more flonums, separated by commas. It
6481 has the same effect as @code{.float}.
6483 The exact kind of floating point numbers emitted depends on how
6484 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
6488 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
6489 numbers in @sc{ieee} format.
6495 @section @code{.size}
6497 This directive is used to set the size associated with a symbol.
6501 @c only print the extra heading if both COFF and ELF are set
6502 @subheading COFF Version
6505 @cindex @code{size} directive (COFF version)
6506 For COFF targets, the @code{.size} directive is only permitted inside
6507 @code{.def}/@code{.endef} pairs. It is used like this:
6510 .size @var{expression}
6514 @samp{.size} is only meaningful when generating COFF format output; when
6515 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6522 @c only print the extra heading if both COFF and ELF are set
6523 @subheading ELF Version
6526 @cindex @code{size} directive (ELF version)
6527 For ELF targets, the @code{.size} directive is used like this:
6530 .size @var{name} , @var{expression}
6533 This directive sets the size associated with a symbol @var{name}.
6534 The size in bytes is computed from @var{expression} which can make use of label
6535 arithmetic. This directive is typically used to set the size of function
6540 @ifclear no-space-dir
6542 @section @code{.skip @var{size} , @var{fill}}
6544 @cindex @code{skip} directive
6545 @cindex filling memory
6546 This directive emits @var{size} bytes, each of value @var{fill}. Both
6547 @var{size} and @var{fill} are absolute expressions. If the comma and
6548 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
6553 @section @code{.sleb128 @var{expressions}}
6555 @cindex @code{sleb128} directive
6556 @var{sleb128} stands for ``signed little endian base 128.'' This is a
6557 compact, variable length representation of numbers used by the DWARF
6558 symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}.
6560 @ifclear no-space-dir
6562 @section @code{.space @var{size} , @var{fill}}
6564 @cindex @code{space} directive
6565 @cindex filling memory
6566 This directive emits @var{size} bytes, each of value @var{fill}. Both
6567 @var{size} and @var{fill} are absolute expressions. If the comma
6568 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
6573 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
6574 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
6575 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
6576 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
6584 @section @code{.stabd, .stabn, .stabs}
6586 @cindex symbolic debuggers, information for
6587 @cindex @code{stab@var{x}} directives
6588 There are three directives that begin @samp{.stab}.
6589 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
6590 The symbols are not entered in the @command{@value{AS}} hash table: they
6591 cannot be referenced elsewhere in the source file.
6592 Up to five fields are required:
6596 This is the symbol's name. It may contain any character except
6597 @samp{\000}, so is more general than ordinary symbol names. Some
6598 debuggers used to code arbitrarily complex structures into symbol names
6602 An absolute expression. The symbol's type is set to the low 8 bits of
6603 this expression. Any bit pattern is permitted, but @code{@value{LD}}
6604 and debuggers choke on silly bit patterns.
6607 An absolute expression. The symbol's ``other'' attribute is set to the
6608 low 8 bits of this expression.
6611 An absolute expression. The symbol's descriptor is set to the low 16
6612 bits of this expression.
6615 An absolute expression which becomes the symbol's value.
6618 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
6619 or @code{.stabs} statement, the symbol has probably already been created;
6620 you get a half-formed symbol in your object file. This is
6621 compatible with earlier assemblers!
6624 @cindex @code{stabd} directive
6625 @item .stabd @var{type} , @var{other} , @var{desc}
6627 The ``name'' of the symbol generated is not even an empty string.
6628 It is a null pointer, for compatibility. Older assemblers used a
6629 null pointer so they didn't waste space in object files with empty
6632 The symbol's value is set to the location counter,
6633 relocatably. When your program is linked, the value of this symbol
6634 is the address of the location counter when the @code{.stabd} was
6637 @cindex @code{stabn} directive
6638 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
6639 The name of the symbol is set to the empty string @code{""}.
6641 @cindex @code{stabs} directive
6642 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
6643 All five fields are specified.
6649 @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
6650 "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
6652 @cindex string, copying to object file
6653 @cindex string8, copying to object file
6654 @cindex string16, copying to object file
6655 @cindex string32, copying to object file
6656 @cindex string64, copying to object file
6657 @cindex @code{string} directive
6658 @cindex @code{string8} directive
6659 @cindex @code{string16} directive
6660 @cindex @code{string32} directive
6661 @cindex @code{string64} directive
6663 Copy the characters in @var{str} to the object file. You may specify more than
6664 one string to copy, separated by commas. Unless otherwise specified for a
6665 particular machine, the assembler marks the end of each string with a 0 byte.
6666 You can use any of the escape sequences described in @ref{Strings,,Strings}.
6668 The variants @code{string16}, @code{string32} and @code{string64} differ from
6669 the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
6670 copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
6671 are stored in target endianness byte order.
6677 .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
6678 .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
6683 @section @code{.struct @var{expression}}
6685 @cindex @code{struct} directive
6686 Switch to the absolute section, and set the section offset to @var{expression},
6687 which must be an absolute expression. You might use this as follows:
6696 This would define the symbol @code{field1} to have the value 0, the symbol
6697 @code{field2} to have the value 4, and the symbol @code{field3} to have the
6698 value 8. Assembly would be left in the absolute section, and you would need to
6699 use a @code{.section} directive of some sort to change to some other section
6700 before further assembly.
6704 @section @code{.subsection @var{name}}
6706 @cindex @code{subsection} directive
6707 @cindex Section Stack
6708 This is one of the ELF section stack manipulation directives. The others are
6709 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
6710 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6713 This directive replaces the current subsection with @code{name}. The current
6714 section is not changed. The replaced subsection is put onto the section stack
6715 in place of the then current top of stack subsection.
6720 @section @code{.symver}
6721 @cindex @code{symver} directive
6722 @cindex symbol versioning
6723 @cindex versions of symbols
6724 Use the @code{.symver} directive to bind symbols to specific version nodes
6725 within a source file. This is only supported on ELF platforms, and is
6726 typically used when assembling files to be linked into a shared library.
6727 There are cases where it may make sense to use this in objects to be bound
6728 into an application itself so as to override a versioned symbol from a
6731 For ELF targets, the @code{.symver} directive can be used like this:
6733 .symver @var{name}, @var{name2@@nodename}
6735 If the symbol @var{name} is defined within the file
6736 being assembled, the @code{.symver} directive effectively creates a symbol
6737 alias with the name @var{name2@@nodename}, and in fact the main reason that we
6738 just don't try and create a regular alias is that the @var{@@} character isn't
6739 permitted in symbol names. The @var{name2} part of the name is the actual name
6740 of the symbol by which it will be externally referenced. The name @var{name}
6741 itself is merely a name of convenience that is used so that it is possible to
6742 have definitions for multiple versions of a function within a single source
6743 file, and so that the compiler can unambiguously know which version of a
6744 function is being mentioned. The @var{nodename} portion of the alias should be
6745 the name of a node specified in the version script supplied to the linker when
6746 building a shared library. If you are attempting to override a versioned
6747 symbol from a shared library, then @var{nodename} should correspond to the
6748 nodename of the symbol you are trying to override.
6750 If the symbol @var{name} is not defined within the file being assembled, all
6751 references to @var{name} will be changed to @var{name2@@nodename}. If no
6752 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
6755 Another usage of the @code{.symver} directive is:
6757 .symver @var{name}, @var{name2@@@@nodename}
6759 In this case, the symbol @var{name} must exist and be defined within
6760 the file being assembled. It is similar to @var{name2@@nodename}. The
6761 difference is @var{name2@@@@nodename} will also be used to resolve
6762 references to @var{name2} by the linker.
6764 The third usage of the @code{.symver} directive is:
6766 .symver @var{name}, @var{name2@@@@@@nodename}
6768 When @var{name} is not defined within the
6769 file being assembled, it is treated as @var{name2@@nodename}. When
6770 @var{name} is defined within the file being assembled, the symbol
6771 name, @var{name}, will be changed to @var{name2@@@@nodename}.
6776 @section @code{.tag @var{structname}}
6778 @cindex COFF structure debugging
6779 @cindex structure debugging, COFF
6780 @cindex @code{tag} directive
6781 This directive is generated by compilers to include auxiliary debugging
6782 information in the symbol table. It is only permitted inside
6783 @code{.def}/@code{.endef} pairs. Tags are used to link structure
6784 definitions in the symbol table with instances of those structures.
6787 @samp{.tag} is only used when generating COFF format output; when
6788 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6794 @section @code{.text @var{subsection}}
6796 @cindex @code{text} directive
6797 Tells @command{@value{AS}} to assemble the following statements onto the end of
6798 the text subsection numbered @var{subsection}, which is an absolute
6799 expression. If @var{subsection} is omitted, subsection number zero
6803 @section @code{.title "@var{heading}"}
6805 @cindex @code{title} directive
6806 @cindex listing control: title line
6807 Use @var{heading} as the title (second line, immediately after the
6808 source file name and pagenumber) when generating assembly listings.
6810 This directive affects subsequent pages, as well as the current page if
6811 it appears within ten lines of the top of a page.
6815 @section @code{.type}
6817 This directive is used to set the type of a symbol.
6821 @c only print the extra heading if both COFF and ELF are set
6822 @subheading COFF Version
6825 @cindex COFF symbol type
6826 @cindex symbol type, COFF
6827 @cindex @code{type} directive (COFF version)
6828 For COFF targets, this directive is permitted only within
6829 @code{.def}/@code{.endef} pairs. It is used like this:
6835 This records the integer @var{int} as the type attribute of a symbol table
6839 @samp{.type} is associated only with COFF format output; when
6840 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
6841 directive but ignores it.
6847 @c only print the extra heading if both COFF and ELF are set
6848 @subheading ELF Version
6851 @cindex ELF symbol type
6852 @cindex symbol type, ELF
6853 @cindex @code{type} directive (ELF version)
6854 For ELF targets, the @code{.type} directive is used like this:
6857 .type @var{name} , @var{type description}
6860 This sets the type of symbol @var{name} to be either a
6861 function symbol or an object symbol. There are five different syntaxes
6862 supported for the @var{type description} field, in order to provide
6863 compatibility with various other assemblers.
6865 Because some of the characters used in these syntaxes (such as @samp{@@} and
6866 @samp{#}) are comment characters for some architectures, some of the syntaxes
6867 below do not work on all architectures. The first variant will be accepted by
6868 the GNU assembler on all architectures so that variant should be used for
6869 maximum portability, if you do not need to assemble your code with other
6872 The syntaxes supported are:
6875 .type <name> STT_<TYPE_IN_UPPER_CASE>
6876 .type <name>,#<type>
6877 .type <name>,@@<type>
6878 .type <name>,%<type>
6879 .type <name>,"<type>"
6882 The types supported are:
6887 Mark the symbol as being a function name.
6890 @itemx gnu_indirect_function
6891 Mark the symbol as an indirect function when evaluated during reloc
6892 processing. (This is only supported on assemblers targeting GNU systems).
6896 Mark the symbol as being a data object.
6900 Mark the symbol as being a thead-local data object.
6904 Mark the symbol as being a common data object.
6908 Does not mark the symbol in any way. It is supported just for completeness.
6910 @item gnu_unique_object
6911 Marks the symbol as being a globally unique data object. The dynamic linker
6912 will make sure that in the entire process there is just one symbol with this
6913 name and type in use. (This is only supported on assemblers targeting GNU
6918 Note: Some targets support extra types in addition to those listed above.
6924 @section @code{.uleb128 @var{expressions}}
6926 @cindex @code{uleb128} directive
6927 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
6928 compact, variable length representation of numbers used by the DWARF
6929 symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}.
6933 @section @code{.val @var{addr}}
6935 @cindex @code{val} directive
6936 @cindex COFF value attribute
6937 @cindex value attribute, COFF
6938 This directive, permitted only within @code{.def}/@code{.endef} pairs,
6939 records the address @var{addr} as the value attribute of a symbol table
6943 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
6944 configured for @code{b.out}, it accepts this directive but ignores it.
6950 @section @code{.version "@var{string}"}
6952 @cindex @code{version} directive
6953 This directive creates a @code{.note} section and places into it an ELF
6954 formatted note of type NT_VERSION. The note's name is set to @code{string}.
6959 @section @code{.vtable_entry @var{table}, @var{offset}}
6961 @cindex @code{vtable_entry} directive
6962 This directive finds or creates a symbol @code{table} and creates a
6963 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
6966 @section @code{.vtable_inherit @var{child}, @var{parent}}
6968 @cindex @code{vtable_inherit} directive
6969 This directive finds the symbol @code{child} and finds or creates the symbol
6970 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
6971 parent whose addend is the value of the child symbol. As a special case the
6972 parent name of @code{0} is treated as referring to the @code{*ABS*} section.
6976 @section @code{.warning "@var{string}"}
6977 @cindex warning directive
6978 Similar to the directive @code{.error}
6979 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
6982 @section @code{.weak @var{names}}
6984 @cindex @code{weak} directive
6985 This directive sets the weak attribute on the comma separated list of symbol
6986 @code{names}. If the symbols do not already exist, they will be created.
6988 On COFF targets other than PE, weak symbols are a GNU extension. This
6989 directive sets the weak attribute on the comma separated list of symbol
6990 @code{names}. If the symbols do not already exist, they will be created.
6992 On the PE target, weak symbols are supported natively as weak aliases.
6993 When a weak symbol is created that is not an alias, GAS creates an
6994 alternate symbol to hold the default value.
6997 @section @code{.weakref @var{alias}, @var{target}}
6999 @cindex @code{weakref} directive
7000 This directive creates an alias to the target symbol that enables the symbol to
7001 be referenced with weak-symbol semantics, but without actually making it weak.
7002 If direct references or definitions of the symbol are present, then the symbol
7003 will not be weak, but if all references to it are through weak references, the
7004 symbol will be marked as weak in the symbol table.
7006 The effect is equivalent to moving all references to the alias to a separate
7007 assembly source file, renaming the alias to the symbol in it, declaring the
7008 symbol as weak there, and running a reloadable link to merge the object files
7009 resulting from the assembly of the new source file and the old source file that
7010 had the references to the alias removed.
7012 The alias itself never makes to the symbol table, and is entirely handled
7013 within the assembler.
7016 @section @code{.word @var{expressions}}
7018 @cindex @code{word} directive
7019 This directive expects zero or more @var{expressions}, of any section,
7020 separated by commas.
7023 For each expression, @command{@value{AS}} emits a 32-bit number.
7026 For each expression, @command{@value{AS}} emits a 16-bit number.
7031 The size of the number emitted, and its byte order,
7032 depend on what target computer the assembly is for.
7035 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
7036 @c happen---32-bit addressability, period; no long/short jumps.
7037 @ifset DIFF-TBL-KLUGE
7038 @cindex difference tables altered
7039 @cindex altered difference tables
7041 @emph{Warning: Special Treatment to support Compilers}
7045 Machines with a 32-bit address space, but that do less than 32-bit
7046 addressing, require the following special treatment. If the machine of
7047 interest to you does 32-bit addressing (or doesn't require it;
7048 @pxref{Machine Dependencies}), you can ignore this issue.
7051 In order to assemble compiler output into something that works,
7052 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
7053 Directives of the form @samp{.word sym1-sym2} are often emitted by
7054 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
7055 directive of the form @samp{.word sym1-sym2}, and the difference between
7056 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
7057 creates a @dfn{secondary jump table}, immediately before the next label.
7058 This secondary jump table is preceded by a short-jump to the
7059 first byte after the secondary table. This short-jump prevents the flow
7060 of control from accidentally falling into the new table. Inside the
7061 table is a long-jump to @code{sym2}. The original @samp{.word}
7062 contains @code{sym1} minus the address of the long-jump to
7065 If there were several occurrences of @samp{.word sym1-sym2} before the
7066 secondary jump table, all of them are adjusted. If there was a
7067 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
7068 long-jump to @code{sym4} is included in the secondary jump table,
7069 and the @code{.word} directives are adjusted to contain @code{sym3}
7070 minus the address of the long-jump to @code{sym4}; and so on, for as many
7071 entries in the original jump table as necessary.
7074 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
7075 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
7076 assembly language programmers.
7079 @c end DIFF-TBL-KLUGE
7081 @ifclear no-space-dir
7083 @section @code{.zero @var{size}}
7085 @cindex @code{zero} directive
7086 @cindex filling memory with zero bytes
7087 This directive emits @var{size} 0-valued bytes. @var{size} must be an absolute
7088 expression. This directive is actually an alias for the @samp{.skip} directive
7089 so in can take an optional second argument of the value to store in the bytes
7090 instead of zero. Using @samp{.zero} in this way would be confusing however.
7094 @section Deprecated Directives
7096 @cindex deprecated directives
7097 @cindex obsolescent directives
7098 One day these directives won't work.
7099 They are included for compatibility with older assemblers.
7106 @node Object Attributes
7107 @chapter Object Attributes
7108 @cindex object attributes
7110 @command{@value{AS}} assembles source files written for a specific architecture
7111 into object files for that architecture. But not all object files are alike.
7112 Many architectures support incompatible variations. For instance, floating
7113 point arguments might be passed in floating point registers if the object file
7114 requires hardware floating point support---or floating point arguments might be
7115 passed in integer registers if the object file supports processors with no
7116 hardware floating point unit. Or, if two objects are built for different
7117 generations of the same architecture, the combination may require the
7118 newer generation at run-time.
7120 This information is useful during and after linking. At link time,
7121 @command{@value{LD}} can warn about incompatible object files. After link
7122 time, tools like @command{gdb} can use it to process the linked file
7125 Compatibility information is recorded as a series of object attributes. Each
7126 attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
7127 string, and indicates who sets the meaning of the tag. The tag is an integer,
7128 and indicates what property the attribute describes. The value may be a string
7129 or an integer, and indicates how the property affects this object. Missing
7130 attributes are the same as attributes with a zero value or empty string value.
7132 Object attributes were developed as part of the ABI for the ARM Architecture.
7133 The file format is documented in @cite{ELF for the ARM Architecture}.
7136 * GNU Object Attributes:: @sc{gnu} Object Attributes
7137 * Defining New Object Attributes:: Defining New Object Attributes
7140 @node GNU Object Attributes
7141 @section @sc{gnu} Object Attributes
7143 The @code{.gnu_attribute} directive records an object attribute
7144 with vendor @samp{gnu}.
7146 Except for @samp{Tag_compatibility}, which has both an integer and a string for
7147 its value, @sc{gnu} attributes have a string value if the tag number is odd and
7148 an integer value if the tag number is even. The second bit (@code{@var{tag} &
7149 2} is set for architecture-independent attributes and clear for
7150 architecture-dependent ones.
7152 @subsection Common @sc{gnu} attributes
7154 These attributes are valid on all architectures.
7157 @item Tag_compatibility (32)
7158 The compatibility attribute takes an integer flag value and a vendor name. If
7159 the flag value is 0, the file is compatible with other toolchains. If it is 1,
7160 then the file is only compatible with the named toolchain. If it is greater
7161 than 1, the file can only be processed by other toolchains under some private
7162 arrangement indicated by the flag value and the vendor name.
7165 @subsection MIPS Attributes
7168 @item Tag_GNU_MIPS_ABI_FP (4)
7169 The floating-point ABI used by this object file. The value will be:
7173 0 for files not affected by the floating-point ABI.
7175 1 for files using the hardware floating-point ABI with a standard
7176 double-precision FPU.
7178 2 for files using the hardware floating-point ABI with a single-precision FPU.
7180 3 for files using the software floating-point ABI.
7182 4 for files using the deprecated hardware floating-point ABI which used 64-bit
7183 floating-point registers, 32-bit general-purpose registers and increased the
7184 number of callee-saved floating-point registers.
7186 5 for files using the hardware floating-point ABI with a double-precision FPU
7187 with either 32-bit or 64-bit floating-point registers and 32-bit
7188 general-purpose registers.
7190 6 for files using the hardware floating-point ABI with 64-bit floating-point
7191 registers and 32-bit general-purpose registers.
7193 7 for files using the hardware floating-point ABI with 64-bit floating-point
7194 registers, 32-bit general-purpose registers and a rule that forbids the
7195 direct use of odd-numbered single-precision floating-point registers.
7199 @subsection PowerPC Attributes
7202 @item Tag_GNU_Power_ABI_FP (4)
7203 The floating-point ABI used by this object file. The value will be:
7207 0 for files not affected by the floating-point ABI.
7209 1 for files using double-precision hardware floating-point ABI.
7211 2 for files using the software floating-point ABI.
7213 3 for files using single-precision hardware floating-point ABI.
7216 @item Tag_GNU_Power_ABI_Vector (8)
7217 The vector ABI used by this object file. The value will be:
7221 0 for files not affected by the vector ABI.
7223 1 for files using general purpose registers to pass vectors.
7225 2 for files using AltiVec registers to pass vectors.
7227 3 for files using SPE registers to pass vectors.
7231 @subsection IBM z Systems Attributes
7234 @item Tag_GNU_S390_ABI_Vector (8)
7235 The vector ABI used by this object file. The value will be:
7239 0 for files not affected by the vector ABI.
7241 1 for files using software vector ABI.
7243 2 for files using hardware vector ABI.
7247 @node Defining New Object Attributes
7248 @section Defining New Object Attributes
7250 If you want to define a new @sc{gnu} object attribute, here are the places you
7251 will need to modify. New attributes should be discussed on the @samp{binutils}
7256 This manual, which is the official register of attributes.
7258 The header for your architecture @file{include/elf}, to define the tag.
7260 The @file{bfd} support file for your architecture, to merge the attribute
7261 and issue any appropriate link warnings.
7263 Test cases in @file{ld/testsuite} for merging and link warnings.
7265 @file{binutils/readelf.c} to display your attribute.
7267 GCC, if you want the compiler to mark the attribute automatically.
7273 @node Machine Dependencies
7274 @chapter Machine Dependent Features
7276 @cindex machine dependencies
7277 The machine instruction sets are (almost by definition) different on
7278 each machine where @command{@value{AS}} runs. Floating point representations
7279 vary as well, and @command{@value{AS}} often supports a few additional
7280 directives or command-line options for compatibility with other
7281 assemblers on a particular platform. Finally, some versions of
7282 @command{@value{AS}} support special pseudo-instructions for branch
7285 This chapter discusses most of these differences, though it does not
7286 include details on any machine's instruction set. For details on that
7287 subject, see the hardware manufacturer's manual.
7291 * AArch64-Dependent:: AArch64 Dependent Features
7294 * Alpha-Dependent:: Alpha Dependent Features
7297 * ARC-Dependent:: ARC Dependent Features
7300 * ARM-Dependent:: ARM Dependent Features
7303 * AVR-Dependent:: AVR Dependent Features
7306 * Blackfin-Dependent:: Blackfin Dependent Features
7309 * CR16-Dependent:: CR16 Dependent Features
7312 * CRIS-Dependent:: CRIS Dependent Features
7315 * D10V-Dependent:: D10V Dependent Features
7318 * D30V-Dependent:: D30V Dependent Features
7321 * Epiphany-Dependent:: EPIPHANY Dependent Features
7324 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7327 * HPPA-Dependent:: HPPA Dependent Features
7330 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
7333 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
7336 * i860-Dependent:: Intel 80860 Dependent Features
7339 * i960-Dependent:: Intel 80960 Dependent Features
7342 * IA-64-Dependent:: Intel IA-64 Dependent Features
7345 * IP2K-Dependent:: IP2K Dependent Features
7348 * LM32-Dependent:: LM32 Dependent Features
7351 * M32C-Dependent:: M32C Dependent Features
7354 * M32R-Dependent:: M32R Dependent Features
7357 * M68K-Dependent:: M680x0 Dependent Features
7360 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
7363 * Meta-Dependent :: Meta Dependent Features
7366 * MicroBlaze-Dependent:: MICROBLAZE Dependent Features
7369 * MIPS-Dependent:: MIPS Dependent Features
7372 * MMIX-Dependent:: MMIX Dependent Features
7375 * MSP430-Dependent:: MSP430 Dependent Features
7378 * NDS32-Dependent:: Andes NDS32 Dependent Features
7381 * NiosII-Dependent:: Altera Nios II Dependent Features
7384 * NS32K-Dependent:: NS32K Dependent Features
7387 * PDP-11-Dependent:: PDP-11 Dependent Features
7390 * PJ-Dependent:: picoJava Dependent Features
7393 * PPC-Dependent:: PowerPC Dependent Features
7396 * RL78-Dependent:: RL78 Dependent Features
7399 * RX-Dependent:: RX Dependent Features
7402 * S/390-Dependent:: IBM S/390 Dependent Features
7405 * SCORE-Dependent:: SCORE Dependent Features
7408 * SH-Dependent:: Renesas / SuperH SH Dependent Features
7409 * SH64-Dependent:: SuperH SH64 Dependent Features
7412 * Sparc-Dependent:: SPARC Dependent Features
7415 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
7418 * TIC6X-Dependent :: TI TMS320C6x Dependent Features
7421 * TILE-Gx-Dependent :: Tilera TILE-Gx Dependent Features
7424 * TILEPro-Dependent :: Tilera TILEPro Dependent Features
7427 * V850-Dependent:: V850 Dependent Features
7430 * Vax-Dependent:: VAX Dependent Features
7433 * Visium-Dependent:: Visium Dependent Features
7436 * XGATE-Dependent:: XGATE Features
7439 * XSTORMY16-Dependent:: XStormy16 Dependent Features
7442 * Xtensa-Dependent:: Xtensa Dependent Features
7445 * Z80-Dependent:: Z80 Dependent Features
7448 * Z8000-Dependent:: Z8000 Dependent Features
7455 @c The following major nodes are *sections* in the GENERIC version, *chapters*
7456 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
7457 @c peculiarity: to preserve cross-references, there must be a node called
7458 @c "Machine Dependencies". Hence the conditional nodenames in each
7459 @c major node below. Node defaulting in makeinfo requires adjacency of
7460 @c node and sectioning commands; hence the repetition of @chapter BLAH
7461 @c in both conditional blocks.
7464 @include c-aarch64.texi
7468 @include c-alpha.texi
7484 @include c-bfin.texi
7488 @include c-cr16.texi
7492 @include c-cris.texi
7497 @node Machine Dependencies
7498 @chapter Machine Dependent Features
7500 The machine instruction sets are different on each Renesas chip family,
7501 and there are also some syntax differences among the families. This
7502 chapter describes the specific @command{@value{AS}} features for each
7506 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7507 * SH-Dependent:: Renesas SH Dependent Features
7514 @include c-d10v.texi
7518 @include c-d30v.texi
7522 @include c-epiphany.texi
7526 @include c-h8300.texi
7530 @include c-hppa.texi
7534 @include c-i370.texi
7538 @include c-i386.texi
7542 @include c-i860.texi
7546 @include c-i960.texi
7550 @include c-ia64.texi
7554 @include c-ip2k.texi
7558 @include c-lm32.texi
7562 @include c-m32c.texi
7566 @include c-m32r.texi
7570 @include c-m68k.texi
7574 @include c-m68hc11.texi
7578 @include c-metag.texi
7582 @include c-microblaze.texi
7586 @include c-mips.texi
7590 @include c-mmix.texi
7594 @include c-msp430.texi
7598 @include c-nds32.texi
7602 @include c-nios2.texi
7606 @include c-ns32k.texi
7610 @include c-pdp11.texi
7622 @include c-rl78.texi
7630 @include c-s390.texi
7634 @include c-score.texi
7639 @include c-sh64.texi
7643 @include c-sparc.texi
7647 @include c-tic54x.texi
7651 @include c-tic6x.texi
7655 @include c-tilegx.texi
7659 @include c-tilepro.texi
7663 @include c-v850.texi
7671 @include c-visium.texi
7675 @include c-xgate.texi
7679 @include c-xstormy16.texi
7683 @include c-xtensa.texi
7695 @c reverse effect of @down at top of generic Machine-Dep chapter
7699 @node Reporting Bugs
7700 @chapter Reporting Bugs
7701 @cindex bugs in assembler
7702 @cindex reporting bugs in assembler
7704 Your bug reports play an essential role in making @command{@value{AS}} reliable.
7706 Reporting a bug may help you by bringing a solution to your problem, or it may
7707 not. But in any case the principal function of a bug report is to help the
7708 entire community by making the next version of @command{@value{AS}} work better.
7709 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
7711 In order for a bug report to serve its purpose, you must include the
7712 information that enables us to fix the bug.
7715 * Bug Criteria:: Have you found a bug?
7716 * Bug Reporting:: How to report bugs
7720 @section Have You Found a Bug?
7721 @cindex bug criteria
7723 If you are not sure whether you have found a bug, here are some guidelines:
7726 @cindex fatal signal
7727 @cindex assembler crash
7728 @cindex crash of assembler
7730 If the assembler gets a fatal signal, for any input whatever, that is a
7731 @command{@value{AS}} bug. Reliable assemblers never crash.
7733 @cindex error on valid input
7735 If @command{@value{AS}} produces an error message for valid input, that is a bug.
7737 @cindex invalid input
7739 If @command{@value{AS}} does not produce an error message for invalid input, that
7740 is a bug. However, you should note that your idea of ``invalid input'' might
7741 be our idea of ``an extension'' or ``support for traditional practice''.
7744 If you are an experienced user of assemblers, your suggestions for improvement
7745 of @command{@value{AS}} are welcome in any case.
7749 @section How to Report Bugs
7751 @cindex assembler bugs, reporting
7753 A number of companies and individuals offer support for @sc{gnu} products. If
7754 you obtained @command{@value{AS}} from a support organization, we recommend you
7755 contact that organization first.
7757 You can find contact information for many support companies and
7758 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
7762 In any event, we also recommend that you send bug reports for @command{@value{AS}}
7766 The fundamental principle of reporting bugs usefully is this:
7767 @strong{report all the facts}. If you are not sure whether to state a
7768 fact or leave it out, state it!
7770 Often people omit facts because they think they know what causes the problem
7771 and assume that some details do not matter. Thus, you might assume that the
7772 name of a symbol you use in an example does not matter. Well, probably it does
7773 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
7774 happens to fetch from the location where that name is stored in memory;
7775 perhaps, if the name were different, the contents of that location would fool
7776 the assembler into doing the right thing despite the bug. Play it safe and
7777 give a specific, complete example. That is the easiest thing for you to do,
7778 and the most helpful.
7780 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
7781 it is new to us. Therefore, always write your bug reports on the assumption
7782 that the bug has not been reported previously.
7784 Sometimes people give a few sketchy facts and ask, ``Does this ring a
7785 bell?'' This cannot help us fix a bug, so it is basically useless. We
7786 respond by asking for enough details to enable us to investigate.
7787 You might as well expedite matters by sending them to begin with.
7789 To enable us to fix the bug, you should include all these things:
7793 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
7794 it with the @samp{--version} argument.
7796 Without this, we will not know whether there is any point in looking for
7797 the bug in the current version of @command{@value{AS}}.
7800 Any patches you may have applied to the @command{@value{AS}} source.
7803 The type of machine you are using, and the operating system name and
7807 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
7811 The command arguments you gave the assembler to assemble your example and
7812 observe the bug. To guarantee you will not omit something important, list them
7813 all. A copy of the Makefile (or the output from make) is sufficient.
7815 If we were to try to guess the arguments, we would probably guess wrong
7816 and then we might not encounter the bug.
7819 A complete input file that will reproduce the bug. If the bug is observed when
7820 the assembler is invoked via a compiler, send the assembler source, not the
7821 high level language source. Most compilers will produce the assembler source
7822 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
7823 the options @samp{-v --save-temps}; this will save the assembler source in a
7824 file with an extension of @file{.s}, and also show you exactly how
7825 @command{@value{AS}} is being run.
7828 A description of what behavior you observe that you believe is
7829 incorrect. For example, ``It gets a fatal signal.''
7831 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
7832 will certainly notice it. But if the bug is incorrect output, we might not
7833 notice unless it is glaringly wrong. You might as well not give us a chance to
7836 Even if the problem you experience is a fatal signal, you should still say so
7837 explicitly. Suppose something strange is going on, such as, your copy of
7838 @command{@value{AS}} is out of sync, or you have encountered a bug in the C
7839 library on your system. (This has happened!) Your copy might crash and ours
7840 would not. If you told us to expect a crash, then when ours fails to crash, we
7841 would know that the bug was not happening for us. If you had not told us to
7842 expect a crash, then we would not be able to draw any conclusion from our
7846 If you wish to suggest changes to the @command{@value{AS}} source, send us context
7847 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
7848 option. Always send diffs from the old file to the new file. If you even
7849 discuss something in the @command{@value{AS}} source, refer to it by context, not
7852 The line numbers in our development sources will not match those in your
7853 sources. Your line numbers would convey no useful information to us.
7856 Here are some things that are not necessary:
7860 A description of the envelope of the bug.
7862 Often people who encounter a bug spend a lot of time investigating
7863 which changes to the input file will make the bug go away and which
7864 changes will not affect it.
7866 This is often time consuming and not very useful, because the way we
7867 will find the bug is by running a single example under the debugger
7868 with breakpoints, not by pure deduction from a series of examples.
7869 We recommend that you save your time for something else.
7871 Of course, if you can find a simpler example to report @emph{instead}
7872 of the original one, that is a convenience for us. Errors in the
7873 output will be easier to spot, running under the debugger will take
7874 less time, and so on.
7876 However, simplification is not vital; if you do not want to do this,
7877 report the bug anyway and send us the entire test case you used.
7880 A patch for the bug.
7882 A patch for the bug does help us if it is a good one. But do not omit
7883 the necessary information, such as the test case, on the assumption that
7884 a patch is all we need. We might see problems with your patch and decide
7885 to fix the problem another way, or we might not understand it at all.
7887 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
7888 construct an example that will make the program follow a certain path through
7889 the code. If you do not send us the example, we will not be able to construct
7890 one, so we will not be able to verify that the bug is fixed.
7892 And if we cannot understand what bug you are trying to fix, or why your
7893 patch should be an improvement, we will not install it. A test case will
7894 help us to understand.
7897 A guess about what the bug is or what it depends on.
7899 Such guesses are usually wrong. Even we cannot guess right about such
7900 things without first using the debugger to find the facts.
7903 @node Acknowledgements
7904 @chapter Acknowledgements
7906 If you have contributed to GAS and your name isn't listed here,
7907 it is not meant as a slight. We just don't know about it. Send mail to the
7908 maintainer, and we'll correct the situation. Currently
7910 the maintainer is Nick Clifton (email address @code{nickc@@redhat.com}).
7912 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
7915 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
7916 information and the 68k series machines, most of the preprocessing pass, and
7917 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
7919 K. Richard Pixley maintained GAS for a while, adding various enhancements and
7920 many bug fixes, including merging support for several processors, breaking GAS
7921 up to handle multiple object file format back ends (including heavy rewrite,
7922 testing, an integration of the coff and b.out back ends), adding configuration
7923 including heavy testing and verification of cross assemblers and file splits
7924 and renaming, converted GAS to strictly ANSI C including full prototypes, added
7925 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
7926 port (including considerable amounts of reverse engineering), a SPARC opcode
7927 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
7928 assertions and made them work, much other reorganization, cleanup, and lint.
7930 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
7931 in format-specific I/O modules.
7933 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
7934 has done much work with it since.
7936 The Intel 80386 machine description was written by Eliot Dresselhaus.
7938 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
7940 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
7941 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
7943 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
7944 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
7945 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
7946 support a.out format.
7948 Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
7949 tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
7950 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
7951 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
7954 John Gilmore built the AMD 29000 support, added @code{.include} support, and
7955 simplified the configuration of which versions accept which directives. He
7956 updated the 68k machine description so that Motorola's opcodes always produced
7957 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
7958 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
7959 cross-compilation support, and one bug in relaxation that took a week and
7960 required the proverbial one-bit fix.
7962 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
7963 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
7964 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
7965 PowerPC assembler, and made a few other minor patches.
7967 Steve Chamberlain made GAS able to generate listings.
7969 Hewlett-Packard contributed support for the HP9000/300.
7971 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
7972 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
7973 formats). This work was supported by both the Center for Software Science at
7974 the University of Utah and Cygnus Support.
7976 Support for ELF format files has been worked on by Mark Eichin of Cygnus
7977 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
7978 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
7979 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
7980 and some initial 64-bit support).
7982 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
7984 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
7985 support for openVMS/Alpha.
7987 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
7990 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
7991 Inc.@: added support for Xtensa processors.
7993 Several engineers at Cygnus Support have also provided many small bug fixes and
7994 configuration enhancements.
7996 Jon Beniston added support for the Lattice Mico32 architecture.
7998 Many others have contributed large or small bugfixes and enhancements. If
7999 you have contributed significant work and are not mentioned on this list, and
8000 want to be, let us know. Some of the history has been lost; we are not
8001 intentionally leaving anyone out.
8003 @node GNU Free Documentation License
8004 @appendix GNU Free Documentation License
8008 @unnumbered AS Index
projects / external / binutils.git / blob