1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright 1991-2013 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{} 1991-2013 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{} 1991-2013 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{--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:}
254 @emph{Target Alpha options:}
256 [@b{-mdebug} | @b{-no-mdebug}]
257 [@b{-replace} | @b{-noreplace}]
258 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
259 [@b{-F}] [@b{-32addr}]
263 @emph{Target ARC options:}
269 @emph{Target ARM options:}
270 @c Don't document the deprecated options
271 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
272 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
273 [@b{-mfpu}=@var{floating-point-format}]
274 [@b{-mfloat-abi}=@var{abi}]
275 [@b{-meabi}=@var{ver}]
278 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
279 @b{-mapcs-reentrant}]
280 [@b{-mthumb-interwork}] [@b{-k}]
284 @emph{Target Blackfin options:}
285 [@b{-mcpu}=@var{processor}[-@var{sirevision}]]
292 @emph{Target CRIS options:}
293 [@b{--underscore} | @b{--no-underscore}]
295 [@b{--emulation=criself} | @b{--emulation=crisaout}]
296 [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}]
297 @c Deprecated -- deliberately not documented.
302 @emph{Target D10V options:}
307 @emph{Target D30V options:}
308 [@b{-O}|@b{-n}|@b{-N}]
312 @emph{Target EPIPHANY options:}
313 [@b{-mepiphany}|@b{-mepiphany16}]
317 @emph{Target H8/300 options:}
321 @c HPPA has no machine-dependent assembler options (yet).
325 @emph{Target i386 options:}
326 [@b{--32}|@b{--x32}|@b{--64}] [@b{-n}]
327 [@b{-march}=@var{CPU}[+@var{EXTENSION}@dots{}]] [@b{-mtune}=@var{CPU}]
331 @emph{Target i960 options:}
332 @c see md_parse_option in tc-i960.c
333 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
335 [@b{-b}] [@b{-no-relax}]
339 @emph{Target IA-64 options:}
340 [@b{-mconstant-gp}|@b{-mauto-pic}]
341 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
343 [@b{-mtune=itanium1}|@b{-mtune=itanium2}]
344 [@b{-munwind-check=warning}|@b{-munwind-check=error}]
345 [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}]
346 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
350 @emph{Target IP2K options:}
351 [@b{-mip2022}|@b{-mip2022ext}]
355 @emph{Target M32C options:}
356 [@b{-m32c}|@b{-m16c}] [-relax] [-h-tick-hex]
360 @emph{Target M32R options:}
361 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
366 @emph{Target M680X0 options:}
367 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
371 @emph{Target M68HC11 options:}
372 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}|@b{-mm9s12x}|@b{-mm9s12xg}]
373 [@b{-mshort}|@b{-mlong}]
374 [@b{-mshort-double}|@b{-mlong-double}]
375 [@b{--force-long-branches}] [@b{--short-branches}]
376 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
377 [@b{--print-opcodes}] [@b{--generate-example}]
381 @emph{Target MCORE options:}
382 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
383 [@b{-mcpu=[210|340]}]
387 @emph{Target Meta options:}
388 [@b{-mcpu=@var{cpu}}] [@b{-mfpu=@var{cpu}}] [@b{-mdsp=@var{cpu}}]
391 @emph{Target MICROBLAZE options:}
392 @c MicroBlaze has no machine-dependent assembler options.
396 @emph{Target MIPS options:}
397 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
398 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
399 [@b{-non_shared}] [@b{-xgot} [@b{-mvxworks-pic}]
400 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
401 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
402 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
403 [@b{-mips64}] [@b{-mips64r2}]
404 [@b{-construct-floats}] [@b{-no-construct-floats}]
405 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
406 [@b{-mips16}] [@b{-no-mips16}]
407 [@b{-mmicromips}] [@b{-mno-micromips}]
408 [@b{-msmartmips}] [@b{-mno-smartmips}]
409 [@b{-mips3d}] [@b{-no-mips3d}]
410 [@b{-mdmx}] [@b{-no-mdmx}]
411 [@b{-mdsp}] [@b{-mno-dsp}]
412 [@b{-mdspr2}] [@b{-mno-dspr2}]
413 [@b{-mmt}] [@b{-mno-mt}]
414 [@b{-mmcu}] [@b{-mno-mcu}]
415 [@b{-mfix7000}] [@b{-mno-fix7000}]
416 [@b{-mfix-vr4120}] [@b{-mno-fix-vr4120}]
417 [@b{-mfix-vr4130}] [@b{-mno-fix-vr4130}]
418 [@b{-mdebug}] [@b{-no-mdebug}]
419 [@b{-mpdr}] [@b{-mno-pdr}]
423 @emph{Target MMIX options:}
424 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
425 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
426 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
427 [@b{--linker-allocated-gregs}]
431 @emph{Target Nios II options:}
432 [@b{-relax-all}] [@b{-relax-section}] [@b{-no-relax}]
437 @emph{Target PDP11 options:}
438 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
439 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
440 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
444 @emph{Target picoJava options:}
449 @emph{Target PowerPC options:}
451 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|@b{-m403}|@b{-m405}|
452 @b{-m440}|@b{-m464}|@b{-m476}|@b{-m7400}|@b{-m7410}|@b{-m7450}|@b{-m7455}|@b{-m750cl}|@b{-mppc64}|
453 @b{-m620}|@b{-me500}|@b{-e500x2}|@b{-me500mc}|@b{-me500mc64}|@b{-me5500}|@b{-me6500}|@b{-mppc64bridge}|
454 @b{-mbooke}|@b{-mpower4}|@b{-mpwr4}|@b{-mpower5}|@b{-mpwr5}|@b{-mpwr5x}|@b{-mpower6}|@b{-mpwr6}|
455 @b{-mpower7}|@b{-mpwr7}|@b{-mpower8}|@b{-mpwr8}|@b{-ma2}|@b{-mcell}|@b{-mspe}|@b{-mtitan}|@b{-me300}|@b{-mcom}]
456 [@b{-many}] [@b{-maltivec}|@b{-mvsx}|@b{-mhtm}|@b{-mvle}]
457 [@b{-mregnames}|@b{-mno-regnames}]
458 [@b{-mrelocatable}|@b{-mrelocatable-lib}|@b{-K PIC}] [@b{-memb}]
459 [@b{-mlittle}|@b{-mlittle-endian}|@b{-le}|@b{-mbig}|@b{-mbig-endian}|@b{-be}]
460 [@b{-msolaris}|@b{-mno-solaris}]
461 [@b{-nops=@var{count}}]
465 @emph{Target RX options:}
466 [@b{-mlittle-endian}|@b{-mbig-endian}]
467 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
468 [@b{-muse-conventional-section-names}]
469 [@b{-msmall-data-limit}]
472 [@b{-mint-register=@var{number}}]
473 [@b{-mgcc-abi}|@b{-mrx-abi}]
477 @emph{Target s390 options:}
478 [@b{-m31}|@b{-m64}] [@b{-mesa}|@b{-mzarch}] [@b{-march}=@var{CPU}]
479 [@b{-mregnames}|@b{-mno-regnames}]
480 [@b{-mwarn-areg-zero}]
484 @emph{Target SCORE options:}
485 [@b{-EB}][@b{-EL}][@b{-FIXDD}][@b{-NWARN}]
486 [@b{-SCORE5}][@b{-SCORE5U}][@b{-SCORE7}][@b{-SCORE3}]
487 [@b{-march=score7}][@b{-march=score3}]
488 [@b{-USE_R1}][@b{-KPIC}][@b{-O0}][@b{-G} @var{num}][@b{-V}]
492 @emph{Target SPARC options:}
493 @c The order here is important. See c-sparc.texi.
494 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
495 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
496 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
501 @emph{Target TIC54X options:}
502 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
503 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
508 @emph{Target TIC6X options:}
509 [@b{-march=@var{arch}}] [@b{-mbig-endian}|@b{-mlittle-endian}]
510 [@b{-mdsbt}|@b{-mno-dsbt}] [@b{-mpid=no}|@b{-mpid=near}|@b{-mpid=far}]
511 [@b{-mpic}|@b{-mno-pic}]
515 @emph{Target TILE-Gx options:}
516 [@b{-m32}|@b{-m64}][@b{-EB}][@b{-EL}]
519 @c TILEPro has no machine-dependent assembler options
524 @emph{Target Xtensa options:}
525 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
526 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
527 [@b{--[no-]transform}]
528 [@b{--rename-section} @var{oldname}=@var{newname}]
533 @emph{Target Z80 options:}
534 [@b{-z80}] [@b{-r800}]
535 [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}]
536 [@b{ -ignore-unportable-instructions}] [@b{-Wnup}]
537 [@b{ -warn-undocumented-instructions}] [@b{-Wud}]
538 [@b{ -warn-unportable-instructions}] [@b{-Wup}]
539 [@b{ -forbid-undocumented-instructions}] [@b{-Fud}]
540 [@b{ -forbid-unportable-instructions}] [@b{-Fup}]
544 @c Z8000 has no machine-dependent assembler options
553 @include at-file.texi
556 Turn on listings, in any of a variety of ways:
560 omit false conditionals
563 omit debugging directives
566 include general information, like @value{AS} version and options passed
569 include high-level source
575 include macro expansions
578 omit forms processing
584 set the name of the listing file
587 You may combine these options; for example, use @samp{-aln} for assembly
588 listing without forms processing. The @samp{=file} option, if used, must be
589 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
592 Begin in alternate macro mode.
594 @xref{Altmacro,,@code{.altmacro}}.
597 @item --compress-debug-sections
598 Compress DWARF debug sections using zlib. The debug sections are renamed
599 to begin with @samp{.zdebug}, and the resulting object file may not be
600 compatible with older linkers and object file utilities.
602 @item --nocompress-debug-sections
603 Do not compress DWARF debug sections. This is the default.
606 Ignored. This option is accepted for script compatibility with calls to
609 @item --debug-prefix-map @var{old}=@var{new}
610 When assembling files in directory @file{@var{old}}, record debugging
611 information describing them as in @file{@var{new}} instead.
613 @item --defsym @var{sym}=@var{value}
614 Define the symbol @var{sym} to be @var{value} before assembling the input file.
615 @var{value} must be an integer constant. As in C, a leading @samp{0x}
616 indicates a hexadecimal value, and a leading @samp{0} indicates an octal
617 value. The value of the symbol can be overridden inside a source file via the
618 use of a @code{.set} pseudo-op.
621 ``fast''---skip whitespace and comment preprocessing (assume source is
626 Generate debugging information for each assembler source line using whichever
627 debug format is preferred by the target. This currently means either STABS,
631 Generate stabs debugging information for each assembler line. This
632 may help debugging assembler code, if the debugger can handle it.
635 Generate stabs debugging information for each assembler line, with GNU
636 extensions that probably only gdb can handle, and that could make other
637 debuggers crash or refuse to read your program. This
638 may help debugging assembler code. Currently the only GNU extension is
639 the location of the current working directory at assembling time.
642 Generate DWARF2 debugging information for each assembler line. This
643 may help debugging assembler code, if the debugger can handle it. Note---this
644 option is only supported by some targets, not all of them.
646 @item --gdwarf-sections
647 Instead of creating a .debug_line section, create a series of
648 .debug_line.@var{foo} sections where @var{foo} is the name of the
649 corresponding code section. For example a code section called @var{.text.func}
650 will have its dwarf line number information placed into a section called
651 @var{.debug_line.text.func}. If the code section is just called @var{.text}
652 then debug line section will still be called just @var{.debug_line} without any
655 @item --size-check=error
656 @itemx --size-check=warning
657 Issue an error or warning for invalid ELF .size directive.
660 Print a summary of the command line options and exit.
663 Print a summary of all target specific options and exit.
666 Add directory @var{dir} to the search list for @code{.include} directives.
669 Don't warn about signed overflow.
672 @ifclear DIFF-TBL-KLUGE
673 This option is accepted but has no effect on the @value{TARGET} family.
675 @ifset DIFF-TBL-KLUGE
676 Issue warnings when difference tables altered for long displacements.
681 Keep (in the symbol table) local symbols. These symbols start with
682 system-specific local label prefixes, typically @samp{.L} for ELF systems
683 or @samp{L} for traditional a.out systems.
688 @item --listing-lhs-width=@var{number}
689 Set the maximum width, in words, of the output data column for an assembler
690 listing to @var{number}.
692 @item --listing-lhs-width2=@var{number}
693 Set the maximum width, in words, of the output data column for continuation
694 lines in an assembler listing to @var{number}.
696 @item --listing-rhs-width=@var{number}
697 Set the maximum width of an input source line, as displayed in a listing, to
700 @item --listing-cont-lines=@var{number}
701 Set the maximum number of lines printed in a listing for a single line of input
704 @item -o @var{objfile}
705 Name the object-file output from @command{@value{AS}} @var{objfile}.
708 Fold the data section into the text section.
710 @kindex --hash-size=@var{number}
711 Set the default size of GAS's hash tables to a prime number close to
712 @var{number}. Increasing this value can reduce the length of time it takes the
713 assembler to perform its tasks, at the expense of increasing the assembler's
714 memory requirements. Similarly reducing this value can reduce the memory
715 requirements at the expense of speed.
717 @item --reduce-memory-overheads
718 This option reduces GAS's memory requirements, at the expense of making the
719 assembly processes slower. Currently this switch is a synonym for
720 @samp{--hash-size=4051}, but in the future it may have other effects as well.
723 Print the maximum space (in bytes) and total time (in seconds) used by
726 @item --strip-local-absolute
727 Remove local absolute symbols from the outgoing symbol table.
731 Print the @command{as} version.
734 Print the @command{as} version and exit.
738 Suppress warning messages.
740 @item --fatal-warnings
741 Treat warnings as errors.
744 Don't suppress warning messages or treat them as errors.
753 Generate an object file even after errors.
755 @item -- | @var{files} @dots{}
756 Standard input, or source files to assemble.
764 @xref{AArch64 Options}, for the options available when @value{AS} is configured
765 for the 64-bit mode of the ARM Architecture (AArch64).
770 The following options are available when @value{AS} is configured for the
771 64-bit mode of the ARM Architecture (AArch64).
774 @include c-aarch64.texi
775 @c ended inside the included file
783 @xref{Alpha Options}, for the options available when @value{AS} is configured
784 for an Alpha processor.
789 The following options are available when @value{AS} is configured for an Alpha
793 @include c-alpha.texi
794 @c ended inside the included file
801 The following options are available when @value{AS} is configured for
806 This option selects the core processor variant.
808 Select either big-endian (-EB) or little-endian (-EL) output.
813 The following options are available when @value{AS} is configured for the ARM
817 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
818 Specify which ARM processor variant is the target.
819 @item -march=@var{architecture}[+@var{extension}@dots{}]
820 Specify which ARM architecture variant is used by the target.
821 @item -mfpu=@var{floating-point-format}
822 Select which Floating Point architecture is the target.
823 @item -mfloat-abi=@var{abi}
824 Select which floating point ABI is in use.
826 Enable Thumb only instruction decoding.
827 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
828 Select which procedure calling convention is in use.
830 Select either big-endian (-EB) or little-endian (-EL) output.
831 @item -mthumb-interwork
832 Specify that the code has been generated with interworking between Thumb and
835 Specify that PIC code has been generated.
843 @xref{Blackfin Options}, for the options available when @value{AS} is
844 configured for the Blackfin processor family.
849 The following options are available when @value{AS} is configured for
850 the Blackfin processor family.
854 @c ended inside the included file
861 See the info pages for documentation of the CRIS-specific options.
865 The following options are available when @value{AS} is configured for
868 @cindex D10V optimization
869 @cindex optimization, D10V
871 Optimize output by parallelizing instructions.
876 The following options are available when @value{AS} is configured for a D30V
879 @cindex D30V optimization
880 @cindex optimization, D30V
882 Optimize output by parallelizing instructions.
886 Warn when nops are generated.
888 @cindex D30V nops after 32-bit multiply
890 Warn when a nop after a 32-bit multiply instruction is generated.
896 The following options are available when @value{AS} is configured for the
897 Adapteva EPIPHANY series.
900 @xref{Epiphany Options}, for the options available when @value{AS} is
901 configured for an Epiphany processor.
906 The following options are available when @value{AS} is configured for
907 an Epiphany processor.
910 @include c-epiphany.texi
911 @c ended inside the included file
919 @xref{H8/300 Options}, for the options available when @value{AS} is configured
920 for an H8/300 processor.
925 The following options are available when @value{AS} is configured for an H8/300
929 @include c-h8300.texi
930 @c ended inside the included file
938 @xref{i386-Options}, for the options available when @value{AS} is
939 configured for an i386 processor.
944 The following options are available when @value{AS} is configured for
949 @c ended inside the included file
956 The following options are available when @value{AS} is configured for the
957 Intel 80960 processor.
960 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
961 Specify which variant of the 960 architecture is the target.
964 Add code to collect statistics about branches taken.
967 Do not alter compare-and-branch instructions for long displacements;
974 The following options are available when @value{AS} is configured for the
980 Specifies that the extended IP2022 instructions are allowed.
983 Restores the default behaviour, which restricts the permitted instructions to
984 just the basic IP2022 ones.
990 The following options are available when @value{AS} is configured for the
991 Renesas M32C and M16C processors.
996 Assemble M32C instructions.
999 Assemble M16C instructions (the default).
1002 Enable support for link-time relaxations.
1005 Support H'00 style hex constants in addition to 0x00 style.
1011 The following options are available when @value{AS} is configured for the
1012 Renesas M32R (formerly Mitsubishi M32R) series.
1017 Specify which processor in the M32R family is the target. The default
1018 is normally the M32R, but this option changes it to the M32RX.
1020 @item --warn-explicit-parallel-conflicts or --Wp
1021 Produce warning messages when questionable parallel constructs are
1024 @item --no-warn-explicit-parallel-conflicts or --Wnp
1025 Do not produce warning messages when questionable parallel constructs are
1032 The following options are available when @value{AS} is configured for the
1033 Motorola 68000 series.
1038 Shorten references to undefined symbols, to one word instead of two.
1040 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
1041 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
1042 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
1043 Specify what processor in the 68000 family is the target. The default
1044 is normally the 68020, but this can be changed at configuration time.
1046 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
1047 The target machine does (or does not) have a floating-point coprocessor.
1048 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
1049 the basic 68000 is not compatible with the 68881, a combination of the
1050 two can be specified, since it's possible to do emulation of the
1051 coprocessor instructions with the main processor.
1053 @item -m68851 | -mno-68851
1054 The target machine does (or does not) have a memory-management
1055 unit coprocessor. The default is to assume an MMU for 68020 and up.
1063 @xref{Nios II Options}, for the options available when @value{AS} is configured
1064 for an Altera Nios II processor.
1068 @c man begin OPTIONS
1069 The following options are available when @value{AS} is configured for an
1070 Altera Nios II processor.
1072 @c man begin INCLUDE
1073 @include c-nios2.texi
1074 @c ended inside the included file
1080 For details about the PDP-11 machine dependent features options,
1081 see @ref{PDP-11-Options}.
1084 @item -mpic | -mno-pic
1085 Generate position-independent (or position-dependent) code. The
1086 default is @option{-mpic}.
1089 @itemx -mall-extensions
1090 Enable all instruction set extensions. This is the default.
1092 @item -mno-extensions
1093 Disable all instruction set extensions.
1095 @item -m@var{extension} | -mno-@var{extension}
1096 Enable (or disable) a particular instruction set extension.
1099 Enable the instruction set extensions supported by a particular CPU, and
1100 disable all other extensions.
1102 @item -m@var{machine}
1103 Enable the instruction set extensions supported by a particular machine
1104 model, and disable all other extensions.
1110 The following options are available when @value{AS} is configured for
1111 a picoJava processor.
1115 @cindex PJ endianness
1116 @cindex endianness, PJ
1117 @cindex big endian output, PJ
1119 Generate ``big endian'' format output.
1121 @cindex little endian output, PJ
1123 Generate ``little endian'' format output.
1129 The following options are available when @value{AS} is configured for the
1130 Motorola 68HC11 or 68HC12 series.
1134 @item -m68hc11 | -m68hc12 | -m68hcs12 | -mm9s12x | -mm9s12xg
1135 Specify what processor is the target. The default is
1136 defined by the configuration option when building the assembler.
1138 @item --xgate-ramoffset
1139 Instruct the linker to offset RAM addresses from S12X address space into
1140 XGATE address space.
1143 Specify to use the 16-bit integer ABI.
1146 Specify to use the 32-bit integer ABI.
1148 @item -mshort-double
1149 Specify to use the 32-bit double ABI.
1152 Specify to use the 64-bit double ABI.
1154 @item --force-long-branches
1155 Relative branches are turned into absolute ones. This concerns
1156 conditional branches, unconditional branches and branches to a
1159 @item -S | --short-branches
1160 Do not turn relative branches into absolute ones
1161 when the offset is out of range.
1163 @item --strict-direct-mode
1164 Do not turn the direct addressing mode into extended addressing mode
1165 when the instruction does not support direct addressing mode.
1167 @item --print-insn-syntax
1168 Print the syntax of instruction in case of error.
1170 @item --print-opcodes
1171 Print the list of instructions with syntax and then exit.
1173 @item --generate-example
1174 Print an example of instruction for each possible instruction and then exit.
1175 This option is only useful for testing @command{@value{AS}}.
1181 The following options are available when @command{@value{AS}} is configured
1182 for the SPARC architecture:
1185 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
1186 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
1187 Explicitly select a variant of the SPARC architecture.
1189 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
1190 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
1192 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
1193 UltraSPARC extensions.
1195 @item -xarch=v8plus | -xarch=v8plusa
1196 For compatibility with the Solaris v9 assembler. These options are
1197 equivalent to -Av8plus and -Av8plusa, respectively.
1200 Warn when the assembler switches to another architecture.
1205 The following options are available when @value{AS} is configured for the 'c54x
1210 Enable extended addressing mode. All addresses and relocations will assume
1211 extended addressing (usually 23 bits).
1212 @item -mcpu=@var{CPU_VERSION}
1213 Sets the CPU version being compiled for.
1214 @item -merrors-to-file @var{FILENAME}
1215 Redirect error output to a file, for broken systems which don't support such
1216 behaviour in the shell.
1221 The following options are available when @value{AS} is configured for
1222 a @sc{mips} processor.
1226 This option sets the largest size of an object that can be referenced
1227 implicitly with the @code{gp} register. It is only accepted for targets that
1228 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
1230 @cindex MIPS endianness
1231 @cindex endianness, MIPS
1232 @cindex big endian output, MIPS
1234 Generate ``big endian'' format output.
1236 @cindex little endian output, MIPS
1238 Generate ``little endian'' format output.
1250 Generate code for a particular @sc{mips} Instruction Set Architecture level.
1251 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
1252 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
1253 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
1254 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and
1256 correspond to generic
1257 @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64},
1258 and @samp{MIPS64 Release 2}
1259 ISA processors, respectively.
1261 @item -march=@var{CPU}
1262 Generate code for a particular @sc{mips} cpu.
1264 @item -mtune=@var{cpu}
1265 Schedule and tune for a particular @sc{mips} cpu.
1269 Cause nops to be inserted if the read of the destination register
1270 of an mfhi or mflo instruction occurs in the following two instructions.
1274 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
1275 section instead of the standard ELF .stabs sections.
1279 Control generation of @code{.pdr} sections.
1283 The register sizes are normally inferred from the ISA and ABI, but these
1284 flags force a certain group of registers to be treated as 32 bits wide at
1285 all times. @samp{-mgp32} controls the size of general-purpose registers
1286 and @samp{-mfp32} controls the size of floating-point registers.
1290 Generate code for the MIPS 16 processor. This is equivalent to putting
1291 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
1292 turns off this option.
1295 @itemx -mno-micromips
1296 Generate code for the microMIPS processor. This is equivalent to putting
1297 @code{.set micromips} at the start of the assembly file. @samp{-mno-micromips}
1298 turns off this option. This is equivalent to putting @code{.set nomicromips}
1299 at the start of the assembly file.
1302 @itemx -mno-smartmips
1303 Enables the SmartMIPS extension to the MIPS32 instruction set. This is
1304 equivalent to putting @code{.set smartmips} at the start of the assembly file.
1305 @samp{-mno-smartmips} turns off this option.
1309 Generate code for the MIPS-3D Application Specific Extension.
1310 This tells the assembler to accept MIPS-3D instructions.
1311 @samp{-no-mips3d} turns off this option.
1315 Generate code for the MDMX Application Specific Extension.
1316 This tells the assembler to accept MDMX instructions.
1317 @samp{-no-mdmx} turns off this option.
1321 Generate code for the DSP Release 1 Application Specific Extension.
1322 This tells the assembler to accept DSP Release 1 instructions.
1323 @samp{-mno-dsp} turns off this option.
1327 Generate code for the DSP Release 2 Application Specific Extension.
1328 This option implies -mdsp.
1329 This tells the assembler to accept DSP Release 2 instructions.
1330 @samp{-mno-dspr2} turns off this option.
1334 Generate code for the MT Application Specific Extension.
1335 This tells the assembler to accept MT instructions.
1336 @samp{-mno-mt} turns off this option.
1340 Generate code for the MCU Application Specific Extension.
1341 This tells the assembler to accept MCU instructions.
1342 @samp{-mno-mcu} turns off this option.
1344 @item --construct-floats
1345 @itemx --no-construct-floats
1346 The @samp{--no-construct-floats} option disables the construction of
1347 double width floating point constants by loading the two halves of the
1348 value into the two single width floating point registers that make up
1349 the double width register. By default @samp{--construct-floats} is
1350 selected, allowing construction of these floating point constants.
1353 @item --emulation=@var{name}
1354 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
1355 for some other target, in all respects, including output format (choosing
1356 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
1357 debugging information or store symbol table information, and default
1358 endianness. The available configuration names are: @samp{mipsecoff},
1359 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
1360 @samp{mipsbelf}. The first two do not alter the default endianness from that
1361 of the primary target for which the assembler was configured; the others change
1362 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
1363 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
1364 selection in any case.
1366 This option is currently supported only when the primary target
1367 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
1368 Furthermore, the primary target or others specified with
1369 @samp{--enable-targets=@dots{}} at configuration time must include support for
1370 the other format, if both are to be available. For example, the Irix 5
1371 configuration includes support for both.
1373 Eventually, this option will support more configurations, with more
1374 fine-grained control over the assembler's behavior, and will be supported for
1378 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1385 Control how to deal with multiplication overflow and division by zero.
1386 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1387 (and only work for Instruction Set Architecture level 2 and higher);
1388 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1392 When this option is used, @command{@value{AS}} will issue a warning every
1393 time it generates a nop instruction from a macro.
1398 The following options are available when @value{AS} is configured for
1404 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1405 The command line option @samp{-nojsri2bsr} can be used to disable it.
1409 Enable or disable the silicon filter behaviour. By default this is disabled.
1410 The default can be overridden by the @samp{-sifilter} command line option.
1413 Alter jump instructions for long displacements.
1415 @item -mcpu=[210|340]
1416 Select the cpu type on the target hardware. This controls which instructions
1420 Assemble for a big endian target.
1423 Assemble for a little endian target.
1432 @xref{Meta Options}, for the options available when @value{AS} is configured
1433 for a Meta processor.
1437 @c man begin OPTIONS
1438 The following options are available when @value{AS} is configured for a
1441 @c man begin INCLUDE
1442 @include c-metag.texi
1443 @c ended inside the included file
1448 @c man begin OPTIONS
1450 See the info pages for documentation of the MMIX-specific options.
1457 @xref{PowerPC-Opts}, for the options available when @value{AS} is configured
1458 for a PowerPC processor.
1462 @c man begin OPTIONS
1463 The following options are available when @value{AS} is configured for a
1466 @c man begin INCLUDE
1468 @c ended inside the included file
1473 @c man begin OPTIONS
1475 See the info pages for documentation of the RX-specific options.
1479 The following options are available when @value{AS} is configured for the s390
1485 Select the word size, either 31/32 bits or 64 bits.
1488 Select the architecture mode, either the Enterprise System
1489 Architecture (esa) or the z/Architecture mode (zarch).
1490 @item -march=@var{processor}
1491 Specify which s390 processor variant is the target, @samp{g6}, @samp{g6},
1492 @samp{z900}, @samp{z990}, @samp{z9-109}, @samp{z9-ec}, @samp{z10},
1493 @samp{z196}, or @samp{zEC12}.
1495 @itemx -mno-regnames
1496 Allow or disallow symbolic names for registers.
1497 @item -mwarn-areg-zero
1498 Warn whenever the operand for a base or index register has been specified
1499 but evaluates to zero.
1507 @xref{TIC6X Options}, for the options available when @value{AS} is configured
1508 for a TMS320C6000 processor.
1512 @c man begin OPTIONS
1513 The following options are available when @value{AS} is configured for a
1514 TMS320C6000 processor.
1516 @c man begin INCLUDE
1517 @include c-tic6x.texi
1518 @c ended inside the included file
1526 @xref{TILE-Gx Options}, for the options available when @value{AS} is configured
1527 for a TILE-Gx processor.
1531 @c man begin OPTIONS
1532 The following options are available when @value{AS} is configured for a TILE-Gx
1535 @c man begin INCLUDE
1536 @include c-tilegx.texi
1537 @c ended inside the included file
1545 @xref{Xtensa Options}, for the options available when @value{AS} is configured
1546 for an Xtensa processor.
1550 @c man begin OPTIONS
1551 The following options are available when @value{AS} is configured for an
1554 @c man begin INCLUDE
1555 @include c-xtensa.texi
1556 @c ended inside the included file
1561 @c man begin OPTIONS
1564 The following options are available when @value{AS} is configured for
1565 a Z80 family processor.
1568 Assemble for Z80 processor.
1570 Assemble for R800 processor.
1571 @item -ignore-undocumented-instructions
1573 Assemble undocumented Z80 instructions that also work on R800 without warning.
1574 @item -ignore-unportable-instructions
1576 Assemble all undocumented Z80 instructions without warning.
1577 @item -warn-undocumented-instructions
1579 Issue a warning for undocumented Z80 instructions that also work on R800.
1580 @item -warn-unportable-instructions
1582 Issue a warning for undocumented Z80 instructions that do not work on R800.
1583 @item -forbid-undocumented-instructions
1585 Treat all undocumented instructions as errors.
1586 @item -forbid-unportable-instructions
1588 Treat undocumented Z80 instructions that do not work on R800 as errors.
1595 * Manual:: Structure of this Manual
1596 * GNU Assembler:: The GNU Assembler
1597 * Object Formats:: Object File Formats
1598 * Command Line:: Command Line
1599 * Input Files:: Input Files
1600 * Object:: Output (Object) File
1601 * Errors:: Error and Warning Messages
1605 @section Structure of this Manual
1607 @cindex manual, structure and purpose
1608 This manual is intended to describe what you need to know to use
1609 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1610 notation for symbols, constants, and expressions; the directives that
1611 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1614 We also cover special features in the @value{TARGET}
1615 configuration of @command{@value{AS}}, including assembler directives.
1618 This manual also describes some of the machine-dependent features of
1619 various flavors of the assembler.
1622 @cindex machine instructions (not covered)
1623 On the other hand, this manual is @emph{not} intended as an introduction
1624 to programming in assembly language---let alone programming in general!
1625 In a similar vein, we make no attempt to introduce the machine
1626 architecture; we do @emph{not} describe the instruction set, standard
1627 mnemonics, registers or addressing modes that are standard to a
1628 particular architecture.
1630 You may want to consult the manufacturer's
1631 machine architecture manual for this information.
1635 For information on the H8/300 machine instruction set, see @cite{H8/300
1636 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1637 Programming Manual} (Renesas).
1640 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1641 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1642 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1643 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1646 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1650 @c I think this is premature---doc@cygnus.com, 17jan1991
1652 Throughout this manual, we assume that you are running @dfn{GNU},
1653 the portable operating system from the @dfn{Free Software
1654 Foundation, Inc.}. This restricts our attention to certain kinds of
1655 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1656 once this assumption is granted examples and definitions need less
1659 @command{@value{AS}} is part of a team of programs that turn a high-level
1660 human-readable series of instructions into a low-level
1661 computer-readable series of instructions. Different versions of
1662 @command{@value{AS}} are used for different kinds of computer.
1665 @c There used to be a section "Terminology" here, which defined
1666 @c "contents", "byte", "word", and "long". Defining "word" to any
1667 @c particular size is confusing when the .word directive may generate 16
1668 @c bits on one machine and 32 bits on another; in general, for the user
1669 @c version of this manual, none of these terms seem essential to define.
1670 @c They were used very little even in the former draft of the manual;
1671 @c this draft makes an effort to avoid them (except in names of
1675 @section The GNU Assembler
1677 @c man begin DESCRIPTION
1679 @sc{gnu} @command{as} is really a family of assemblers.
1681 This manual describes @command{@value{AS}}, a member of that family which is
1682 configured for the @value{TARGET} architectures.
1684 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1685 should find a fairly similar environment when you use it on another
1686 architecture. Each version has much in common with the others,
1687 including object file formats, most assembler directives (often called
1688 @dfn{pseudo-ops}) and assembler syntax.@refill
1690 @cindex purpose of @sc{gnu} assembler
1691 @command{@value{AS}} is primarily intended to assemble the output of the
1692 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1693 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1694 assemble correctly everything that other assemblers for the same
1695 machine would assemble.
1697 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1700 @c This remark should appear in generic version of manual; assumption
1701 @c here is that generic version sets M680x0.
1702 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1703 assembler for the same architecture; for example, we know of several
1704 incompatible versions of 680x0 assembly language syntax.
1709 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1710 program in one pass of the source file. This has a subtle impact on the
1711 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1713 @node Object Formats
1714 @section Object File Formats
1716 @cindex object file format
1717 The @sc{gnu} assembler can be configured to produce several alternative
1718 object file formats. For the most part, this does not affect how you
1719 write assembly language programs; but directives for debugging symbols
1720 are typically different in different file formats. @xref{Symbol
1721 Attributes,,Symbol Attributes}.
1724 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1725 @value{OBJ-NAME} format object files.
1727 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1729 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1730 @code{b.out} or COFF format object files.
1733 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1734 SOM or ELF format object files.
1739 @section Command Line
1741 @cindex command line conventions
1743 After the program name @command{@value{AS}}, the command line may contain
1744 options and file names. Options may appear in any order, and may be
1745 before, after, or between file names. The order of file names is
1748 @cindex standard input, as input file
1750 @file{--} (two hyphens) by itself names the standard input file
1751 explicitly, as one of the files for @command{@value{AS}} to assemble.
1753 @cindex options, command line
1754 Except for @samp{--} any command line argument that begins with a
1755 hyphen (@samp{-}) is an option. Each option changes the behavior of
1756 @command{@value{AS}}. No option changes the way another option works. An
1757 option is a @samp{-} followed by one or more letters; the case of
1758 the letter is important. All options are optional.
1760 Some options expect exactly one file name to follow them. The file
1761 name may either immediately follow the option's letter (compatible
1762 with older assemblers) or it may be the next command argument (@sc{gnu}
1763 standard). These two command lines are equivalent:
1766 @value{AS} -o my-object-file.o mumble.s
1767 @value{AS} -omy-object-file.o mumble.s
1771 @section Input Files
1774 @cindex source program
1775 @cindex files, input
1776 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1777 describe the program input to one run of @command{@value{AS}}. The program may
1778 be in one or more files; how the source is partitioned into files
1779 doesn't change the meaning of the source.
1781 @c I added "con" prefix to "catenation" just to prove I can overcome my
1782 @c APL training... doc@cygnus.com
1783 The source program is a concatenation of the text in all the files, in the
1786 @c man begin DESCRIPTION
1787 Each time you run @command{@value{AS}} it assembles exactly one source
1788 program. The source program is made up of one or more files.
1789 (The standard input is also a file.)
1791 You give @command{@value{AS}} a command line that has zero or more input file
1792 names. The input files are read (from left file name to right). A
1793 command line argument (in any position) that has no special meaning
1794 is taken to be an input file name.
1796 If you give @command{@value{AS}} no file names it attempts to read one input file
1797 from the @command{@value{AS}} standard input, which is normally your terminal. You
1798 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1801 Use @samp{--} if you need to explicitly name the standard input file
1802 in your command line.
1804 If the source is empty, @command{@value{AS}} produces a small, empty object
1809 @subheading Filenames and Line-numbers
1811 @cindex input file linenumbers
1812 @cindex line numbers, in input files
1813 There are two ways of locating a line in the input file (or files) and
1814 either may be used in reporting error messages. One way refers to a line
1815 number in a physical file; the other refers to a line number in a
1816 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1818 @dfn{Physical files} are those files named in the command line given
1819 to @command{@value{AS}}.
1821 @dfn{Logical files} are simply names declared explicitly by assembler
1822 directives; they bear no relation to physical files. Logical file names help
1823 error messages reflect the original source file, when @command{@value{AS}} source
1824 is itself synthesized from other files. @command{@value{AS}} understands the
1825 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1826 @ref{File,,@code{.file}}.
1829 @section Output (Object) File
1835 Every time you run @command{@value{AS}} it produces an output file, which is
1836 your assembly language program translated into numbers. This file
1837 is the object file. Its default name is
1845 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1847 You can give it another name by using the @option{-o} option. Conventionally,
1848 object file names end with @file{.o}. The default name is used for historical
1849 reasons: older assemblers were capable of assembling self-contained programs
1850 directly into a runnable program. (For some formats, this isn't currently
1851 possible, but it can be done for the @code{a.out} format.)
1855 The object file is meant for input to the linker @code{@value{LD}}. It contains
1856 assembled program code, information to help @code{@value{LD}} integrate
1857 the assembled program into a runnable file, and (optionally) symbolic
1858 information for the debugger.
1860 @c link above to some info file(s) like the description of a.out.
1861 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1864 @section Error and Warning Messages
1866 @c man begin DESCRIPTION
1868 @cindex error messages
1869 @cindex warning messages
1870 @cindex messages from assembler
1871 @command{@value{AS}} may write warnings and error messages to the standard error
1872 file (usually your terminal). This should not happen when a compiler
1873 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1874 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1875 grave problem that stops the assembly.
1879 @cindex format of warning messages
1880 Warning messages have the format
1883 file_name:@b{NNN}:Warning Message Text
1887 @cindex line numbers, in warnings/errors
1888 (where @b{NNN} is a line number). If a logical file name has been given
1889 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1890 the current input file is used. If a logical line number was given
1892 (@pxref{Line,,@code{.line}})
1894 then it is used to calculate the number printed,
1895 otherwise the actual line in the current source file is printed. The
1896 message text is intended to be self explanatory (in the grand Unix
1899 @cindex format of error messages
1900 Error messages have the format
1902 file_name:@b{NNN}:FATAL:Error Message Text
1904 The file name and line number are derived as for warning
1905 messages. The actual message text may be rather less explanatory
1906 because many of them aren't supposed to happen.
1909 @chapter Command-Line Options
1911 @cindex options, all versions of assembler
1912 This chapter describes command-line options available in @emph{all}
1913 versions of the @sc{gnu} assembler; see @ref{Machine Dependencies},
1914 for options specific
1916 to the @value{TARGET} target.
1919 to particular machine architectures.
1922 @c man begin DESCRIPTION
1924 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
1925 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1926 The assembler arguments must be separated from each other (and the @samp{-Wa})
1927 by commas. For example:
1930 gcc -c -g -O -Wa,-alh,-L file.c
1934 This passes two options to the assembler: @samp{-alh} (emit a listing to
1935 standard output with high-level and assembly source) and @samp{-L} (retain
1936 local symbols in the symbol table).
1938 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1939 command-line options are automatically passed to the assembler by the compiler.
1940 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1941 precisely what options it passes to each compilation pass, including the
1947 * a:: -a[cdghlns] enable listings
1948 * alternate:: --alternate enable alternate macro syntax
1949 * D:: -D for compatibility
1950 * f:: -f to work faster
1951 * I:: -I for .include search path
1952 @ifclear DIFF-TBL-KLUGE
1953 * K:: -K for compatibility
1955 @ifset DIFF-TBL-KLUGE
1956 * K:: -K for difference tables
1959 * L:: -L to retain local symbols
1960 * listing:: --listing-XXX to configure listing output
1961 * M:: -M or --mri to assemble in MRI compatibility mode
1962 * MD:: --MD for dependency tracking
1963 * o:: -o to name the object file
1964 * R:: -R to join data and text sections
1965 * statistics:: --statistics to see statistics about assembly
1966 * traditional-format:: --traditional-format for compatible output
1967 * v:: -v to announce version
1968 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1969 * Z:: -Z to make object file even after errors
1973 @section Enable Listings: @option{-a[cdghlns]}
1983 @cindex listings, enabling
1984 @cindex assembly listings, enabling
1986 These options enable listing output from the assembler. By itself,
1987 @samp{-a} requests high-level, assembly, and symbols listing.
1988 You can use other letters to select specific options for the list:
1989 @samp{-ah} requests a high-level language listing,
1990 @samp{-al} requests an output-program assembly listing, and
1991 @samp{-as} requests a symbol table listing.
1992 High-level listings require that a compiler debugging option like
1993 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1996 Use the @samp{-ag} option to print a first section with general assembly
1997 information, like @value{AS} version, switches passed, or time stamp.
1999 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
2000 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
2001 other conditional), or a true @code{.if} followed by an @code{.else}, will be
2002 omitted from the listing.
2004 Use the @samp{-ad} option to omit debugging directives from the
2007 Once you have specified one of these options, you can further control
2008 listing output and its appearance using the directives @code{.list},
2009 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
2011 The @samp{-an} option turns off all forms processing.
2012 If you do not request listing output with one of the @samp{-a} options, the
2013 listing-control directives have no effect.
2015 The letters after @samp{-a} may be combined into one option,
2016 @emph{e.g.}, @samp{-aln}.
2018 Note if the assembler source is coming from the standard input (e.g.,
2020 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
2021 is being used) then the listing will not contain any comments or preprocessor
2022 directives. This is because the listing code buffers input source lines from
2023 stdin only after they have been preprocessed by the assembler. This reduces
2024 memory usage and makes the code more efficient.
2027 @section @option{--alternate}
2030 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
2033 @section @option{-D}
2036 This option has no effect whatsoever, but it is accepted to make it more
2037 likely that scripts written for other assemblers also work with
2038 @command{@value{AS}}.
2041 @section Work Faster: @option{-f}
2044 @cindex trusted compiler
2045 @cindex faster processing (@option{-f})
2046 @samp{-f} should only be used when assembling programs written by a
2047 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
2048 and comment preprocessing on
2049 the input file(s) before assembling them. @xref{Preprocessing,
2053 @emph{Warning:} if you use @samp{-f} when the files actually need to be
2054 preprocessed (if they contain comments, for example), @command{@value{AS}} does
2059 @section @code{.include} Search Path: @option{-I} @var{path}
2061 @kindex -I @var{path}
2062 @cindex paths for @code{.include}
2063 @cindex search path for @code{.include}
2064 @cindex @code{include} directive search path
2065 Use this option to add a @var{path} to the list of directories
2066 @command{@value{AS}} searches for files specified in @code{.include}
2067 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
2068 many times as necessary to include a variety of paths. The current
2069 working directory is always searched first; after that, @command{@value{AS}}
2070 searches any @samp{-I} directories in the same order as they were
2071 specified (left to right) on the command line.
2074 @section Difference Tables: @option{-K}
2077 @ifclear DIFF-TBL-KLUGE
2078 On the @value{TARGET} family, this option is allowed, but has no effect. It is
2079 permitted for compatibility with the @sc{gnu} assembler on other platforms,
2080 where it can be used to warn when the assembler alters the machine code
2081 generated for @samp{.word} directives in difference tables. The @value{TARGET}
2082 family does not have the addressing limitations that sometimes lead to this
2083 alteration on other platforms.
2086 @ifset DIFF-TBL-KLUGE
2087 @cindex difference tables, warning
2088 @cindex warning for altered difference tables
2089 @command{@value{AS}} sometimes alters the code emitted for directives of the
2090 form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}.
2091 You can use the @samp{-K} option if you want a warning issued when this
2096 @section Include Local Symbols: @option{-L}
2099 @cindex local symbols, retaining in output
2100 Symbols beginning with system-specific local label prefixes, typically
2101 @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are
2102 called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see
2103 such symbols when debugging, because they are intended for the use of
2104 programs (like compilers) that compose assembler programs, not for your
2105 notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard
2106 such symbols, so you do not normally debug with them.
2108 This option tells @command{@value{AS}} to retain those local symbols
2109 in the object file. Usually if you do this you also tell the linker
2110 @code{@value{LD}} to preserve those symbols.
2113 @section Configuring listing output: @option{--listing}
2115 The listing feature of the assembler can be enabled via the command line switch
2116 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
2117 hex dump of the corresponding locations in the output object file, and displays
2118 them as a listing file. The format of this listing can be controlled by
2119 directives inside the assembler source (i.e., @code{.list} (@pxref{List}),
2120 @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}),
2121 @code{.psize} (@pxref{Psize}), and
2122 @code{.eject} (@pxref{Eject}) and also by the following switches:
2125 @item --listing-lhs-width=@samp{number}
2126 @kindex --listing-lhs-width
2127 @cindex Width of first line disassembly output
2128 Sets the maximum width, in words, of the first line of the hex byte dump. This
2129 dump appears on the left hand side of the listing output.
2131 @item --listing-lhs-width2=@samp{number}
2132 @kindex --listing-lhs-width2
2133 @cindex Width of continuation lines of disassembly output
2134 Sets the maximum width, in words, of any further lines of the hex byte dump for
2135 a given input source line. If this value is not specified, it defaults to being
2136 the same as the value specified for @samp{--listing-lhs-width}. If neither
2137 switch is used the default is to one.
2139 @item --listing-rhs-width=@samp{number}
2140 @kindex --listing-rhs-width
2141 @cindex Width of source line output
2142 Sets the maximum width, in characters, of the source line that is displayed
2143 alongside the hex dump. The default value for this parameter is 100. The
2144 source line is displayed on the right hand side of the listing output.
2146 @item --listing-cont-lines=@samp{number}
2147 @kindex --listing-cont-lines
2148 @cindex Maximum number of continuation lines
2149 Sets the maximum number of continuation lines of hex dump that will be
2150 displayed for a given single line of source input. The default value is 4.
2154 @section Assemble in MRI Compatibility Mode: @option{-M}
2157 @cindex MRI compatibility mode
2158 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
2159 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
2160 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
2161 configured target) assembler from Microtec Research. The exact nature of the
2162 MRI syntax will not be documented here; see the MRI manuals for more
2163 information. Note in particular that the handling of macros and macro
2164 arguments is somewhat different. The purpose of this option is to permit
2165 assembling existing MRI assembler code using @command{@value{AS}}.
2167 The MRI compatibility is not complete. Certain operations of the MRI assembler
2168 depend upon its object file format, and can not be supported using other object
2169 file formats. Supporting these would require enhancing each object file format
2170 individually. These are:
2173 @item global symbols in common section
2175 The m68k MRI assembler supports common sections which are merged by the linker.
2176 Other object file formats do not support this. @command{@value{AS}} handles
2177 common sections by treating them as a single common symbol. It permits local
2178 symbols to be defined within a common section, but it can not support global
2179 symbols, since it has no way to describe them.
2181 @item complex relocations
2183 The MRI assemblers support relocations against a negated section address, and
2184 relocations which combine the start addresses of two or more sections. These
2185 are not support by other object file formats.
2187 @item @code{END} pseudo-op specifying start address
2189 The MRI @code{END} pseudo-op permits the specification of a start address.
2190 This is not supported by other object file formats. The start address may
2191 instead be specified using the @option{-e} option to the linker, or in a linker
2194 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
2196 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
2197 name to the output file. This is not supported by other object file formats.
2199 @item @code{ORG} pseudo-op
2201 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
2202 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
2203 which changes the location within the current section. Absolute sections are
2204 not supported by other object file formats. The address of a section may be
2205 assigned within a linker script.
2208 There are some other features of the MRI assembler which are not supported by
2209 @command{@value{AS}}, typically either because they are difficult or because they
2210 seem of little consequence. Some of these may be supported in future releases.
2214 @item EBCDIC strings
2216 EBCDIC strings are not supported.
2218 @item packed binary coded decimal
2220 Packed binary coded decimal is not supported. This means that the @code{DC.P}
2221 and @code{DCB.P} pseudo-ops are not supported.
2223 @item @code{FEQU} pseudo-op
2225 The m68k @code{FEQU} pseudo-op is not supported.
2227 @item @code{NOOBJ} pseudo-op
2229 The m68k @code{NOOBJ} pseudo-op is not supported.
2231 @item @code{OPT} branch control options
2233 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
2234 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
2235 relaxes all branches, whether forward or backward, to an appropriate size, so
2236 these options serve no purpose.
2238 @item @code{OPT} list control options
2240 The following m68k @code{OPT} list control options are ignored: @code{C},
2241 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
2242 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
2244 @item other @code{OPT} options
2246 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
2247 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
2249 @item @code{OPT} @code{D} option is default
2251 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
2252 @code{OPT NOD} may be used to turn it off.
2254 @item @code{XREF} pseudo-op.
2256 The m68k @code{XREF} pseudo-op is ignored.
2258 @item @code{.debug} pseudo-op
2260 The i960 @code{.debug} pseudo-op is not supported.
2262 @item @code{.extended} pseudo-op
2264 The i960 @code{.extended} pseudo-op is not supported.
2266 @item @code{.list} pseudo-op.
2268 The various options of the i960 @code{.list} pseudo-op are not supported.
2270 @item @code{.optimize} pseudo-op
2272 The i960 @code{.optimize} pseudo-op is not supported.
2274 @item @code{.output} pseudo-op
2276 The i960 @code{.output} pseudo-op is not supported.
2278 @item @code{.setreal} pseudo-op
2280 The i960 @code{.setreal} pseudo-op is not supported.
2285 @section Dependency Tracking: @option{--MD}
2288 @cindex dependency tracking
2291 @command{@value{AS}} can generate a dependency file for the file it creates. This
2292 file consists of a single rule suitable for @code{make} describing the
2293 dependencies of the main source file.
2295 The rule is written to the file named in its argument.
2297 This feature is used in the automatic updating of makefiles.
2300 @section Name the Object File: @option{-o}
2303 @cindex naming object file
2304 @cindex object file name
2305 There is always one object file output when you run @command{@value{AS}}. By
2306 default it has the name
2309 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
2323 You use this option (which takes exactly one filename) to give the
2324 object file a different name.
2326 Whatever the object file is called, @command{@value{AS}} overwrites any
2327 existing file of the same name.
2330 @section Join Data and Text Sections: @option{-R}
2333 @cindex data and text sections, joining
2334 @cindex text and data sections, joining
2335 @cindex joining text and data sections
2336 @cindex merging text and data sections
2337 @option{-R} tells @command{@value{AS}} to write the object file as if all
2338 data-section data lives in the text section. This is only done at
2339 the very last moment: your binary data are the same, but data
2340 section parts are relocated differently. The data section part of
2341 your object file is zero bytes long because all its bytes are
2342 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
2344 When you specify @option{-R} it would be possible to generate shorter
2345 address displacements (because we do not have to cross between text and
2346 data section). We refrain from doing this simply for compatibility with
2347 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
2350 When @command{@value{AS}} is configured for COFF or ELF output,
2351 this option is only useful if you use sections named @samp{.text} and
2356 @option{-R} is not supported for any of the HPPA targets. Using
2357 @option{-R} generates a warning from @command{@value{AS}}.
2361 @section Display Assembly Statistics: @option{--statistics}
2363 @kindex --statistics
2364 @cindex statistics, about assembly
2365 @cindex time, total for assembly
2366 @cindex space used, maximum for assembly
2367 Use @samp{--statistics} to display two statistics about the resources used by
2368 @command{@value{AS}}: the maximum amount of space allocated during the assembly
2369 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
2372 @node traditional-format
2373 @section Compatible Output: @option{--traditional-format}
2375 @kindex --traditional-format
2376 For some targets, the output of @command{@value{AS}} is different in some ways
2377 from the output of some existing assembler. This switch requests
2378 @command{@value{AS}} to use the traditional format instead.
2380 For example, it disables the exception frame optimizations which
2381 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
2384 @section Announce Version: @option{-v}
2388 @cindex assembler version
2389 @cindex version of assembler
2390 You can find out what version of as is running by including the
2391 option @samp{-v} (which you can also spell as @samp{-version}) on the
2395 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
2397 @command{@value{AS}} should never give a warning or error message when
2398 assembling compiler output. But programs written by people often
2399 cause @command{@value{AS}} to give a warning that a particular assumption was
2400 made. All such warnings are directed to the standard error file.
2404 @cindex suppressing warnings
2405 @cindex warnings, suppressing
2406 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
2407 This only affects the warning messages: it does not change any particular of
2408 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
2411 @kindex --fatal-warnings
2412 @cindex errors, caused by warnings
2413 @cindex warnings, causing error
2414 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
2415 files that generate warnings to be in error.
2418 @cindex warnings, switching on
2419 You can switch these options off again by specifying @option{--warn}, which
2420 causes warnings to be output as usual.
2423 @section Generate Object File in Spite of Errors: @option{-Z}
2424 @cindex object file, after errors
2425 @cindex errors, continuing after
2426 After an error message, @command{@value{AS}} normally produces no output. If for
2427 some reason you are interested in object file output even after
2428 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
2429 option. If there are any errors, @command{@value{AS}} continues anyways, and
2430 writes an object file after a final warning message of the form @samp{@var{n}
2431 errors, @var{m} warnings, generating bad object file.}
2436 @cindex machine-independent syntax
2437 @cindex syntax, machine-independent
2438 This chapter describes the machine-independent syntax allowed in a
2439 source file. @command{@value{AS}} syntax is similar to what many other
2440 assemblers use; it is inspired by the BSD 4.2
2445 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
2449 * Preprocessing:: Preprocessing
2450 * Whitespace:: Whitespace
2451 * Comments:: Comments
2452 * Symbol Intro:: Symbols
2453 * Statements:: Statements
2454 * Constants:: Constants
2458 @section Preprocessing
2460 @cindex preprocessing
2461 The @command{@value{AS}} internal preprocessor:
2463 @cindex whitespace, removed by preprocessor
2465 adjusts and removes extra whitespace. It leaves one space or tab before
2466 the keywords on a line, and turns any other whitespace on the line into
2469 @cindex comments, removed by preprocessor
2471 removes all comments, replacing them with a single space, or an
2472 appropriate number of newlines.
2474 @cindex constants, converted by preprocessor
2476 converts character constants into the appropriate numeric values.
2479 It does not do macro processing, include file handling, or
2480 anything else you may get from your C compiler's preprocessor. You can
2481 do include file processing with the @code{.include} directive
2482 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2483 to get other ``CPP'' style preprocessing by giving the input file a
2484 @samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of
2485 Output, gcc.info, Using GNU CC}.
2487 Excess whitespace, comments, and character constants
2488 cannot be used in the portions of the input text that are not
2491 @cindex turning preprocessing on and off
2492 @cindex preprocessing, turning on and off
2495 If the first line of an input file is @code{#NO_APP} or if you use the
2496 @samp{-f} option, whitespace and comments are not removed from the input file.
2497 Within an input file, you can ask for whitespace and comment removal in
2498 specific portions of the by putting a line that says @code{#APP} before the
2499 text that may contain whitespace or comments, and putting a line that says
2500 @code{#NO_APP} after this text. This feature is mainly intend to support
2501 @code{asm} statements in compilers whose output is otherwise free of comments
2508 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2509 Whitespace is used to separate symbols, and to make programs neater for
2510 people to read. Unless within character constants
2511 (@pxref{Characters,,Character Constants}), any whitespace means the same
2512 as exactly one space.
2518 There are two ways of rendering comments to @command{@value{AS}}. In both
2519 cases the comment is equivalent to one space.
2521 Anything from @samp{/*} through the next @samp{*/} is a comment.
2522 This means you may not nest these comments.
2526 The only way to include a newline ('\n') in a comment
2527 is to use this sort of comment.
2530 /* This sort of comment does not nest. */
2533 @cindex line comment character
2534 Anything from a @dfn{line comment} character up to the next newline is
2535 considered a comment and is ignored. The line comment character is target
2536 specific, and some targets multiple comment characters. Some targets also have
2537 line comment characters that only work if they are the first character on a
2538 line. Some targets use a sequence of two characters to introduce a line
2539 comment. Some targets can also change their line comment characters depending
2540 upon command line options that have been used. For more details see the
2541 @emph{Syntax} section in the documentation for individual targets.
2543 If the line comment character is the hash sign (@samp{#}) then it still has the
2544 special ability to enable and disable preprocessing (@pxref{Preprocessing}) and
2545 to specify logical line numbers:
2548 @cindex lines starting with @code{#}
2549 @cindex logical line numbers
2550 To be compatible with past assemblers, lines that begin with @samp{#} have a
2551 special interpretation. Following the @samp{#} should be an absolute
2552 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2553 line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a
2554 new logical file name. The rest of the line, if any, should be whitespace.
2556 If the first non-whitespace characters on the line are not numeric,
2557 the line is ignored. (Just like a comment.)
2560 # This is an ordinary comment.
2561 # 42-6 "new_file_name" # New logical file name
2562 # This is logical line # 36.
2564 This feature is deprecated, and may disappear from future versions
2565 of @command{@value{AS}}.
2570 @cindex characters used in symbols
2571 @ifclear SPECIAL-SYMS
2572 A @dfn{symbol} is one or more characters chosen from the set of all
2573 letters (both upper and lower case), digits and the three characters
2579 A @dfn{symbol} is one or more characters chosen from the set of all
2580 letters (both upper and lower case), digits and the three characters
2581 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2587 On most machines, you can also use @code{$} in symbol names; exceptions
2588 are noted in @ref{Machine Dependencies}.
2590 No symbol may begin with a digit. Case is significant.
2591 There is no length limit: all characters are significant. Multibyte characters
2592 are supported. Symbols are delimited by characters not in that set, or by the
2593 beginning of a file (since the source program must end with a newline, the end
2594 of a file is not a possible symbol delimiter). @xref{Symbols}.
2595 @cindex length of symbols
2600 @cindex statements, structure of
2601 @cindex line separator character
2602 @cindex statement separator character
2604 A @dfn{statement} ends at a newline character (@samp{\n}) or a
2605 @dfn{line separator character}. The line separator character is target
2606 specific and described in the @emph{Syntax} section of each
2607 target's documentation. Not all targets support a line separator character.
2608 The newline or line separator character is considered to be part of the
2609 preceding statement. Newlines and separators within character constants are an
2610 exception: they do not end statements.
2612 @cindex newline, required at file end
2613 @cindex EOF, newline must precede
2614 It is an error to end any statement with end-of-file: the last
2615 character of any input file should be a newline.@refill
2617 An empty statement is allowed, and may include whitespace. It is ignored.
2619 @cindex instructions and directives
2620 @cindex directives and instructions
2621 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2622 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2624 A statement begins with zero or more labels, optionally followed by a
2625 key symbol which determines what kind of statement it is. The key
2626 symbol determines the syntax of the rest of the statement. If the
2627 symbol begins with a dot @samp{.} then the statement is an assembler
2628 directive: typically valid for any computer. If the symbol begins with
2629 a letter the statement is an assembly language @dfn{instruction}: it
2630 assembles into a machine language instruction.
2632 Different versions of @command{@value{AS}} for different computers
2633 recognize different instructions. In fact, the same symbol may
2634 represent a different instruction in a different computer's assembly
2638 @cindex @code{:} (label)
2639 @cindex label (@code{:})
2640 A label is a symbol immediately followed by a colon (@code{:}).
2641 Whitespace before a label or after a colon is permitted, but you may not
2642 have whitespace between a label's symbol and its colon. @xref{Labels}.
2645 For HPPA targets, labels need not be immediately followed by a colon, but
2646 the definition of a label must begin in column zero. This also implies that
2647 only one label may be defined on each line.
2651 label: .directive followed by something
2652 another_label: # This is an empty statement.
2653 instruction operand_1, operand_2, @dots{}
2660 A constant is a number, written so that its value is known by
2661 inspection, without knowing any context. Like this:
2664 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2665 .ascii "Ring the bell\7" # A string constant.
2666 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2667 .float 0f-314159265358979323846264338327\
2668 95028841971.693993751E-40 # - pi, a flonum.
2673 * Characters:: Character Constants
2674 * Numbers:: Number Constants
2678 @subsection Character Constants
2680 @cindex character constants
2681 @cindex constants, character
2682 There are two kinds of character constants. A @dfn{character} stands
2683 for one character in one byte and its value may be used in
2684 numeric expressions. String constants (properly called string
2685 @emph{literals}) are potentially many bytes and their values may not be
2686 used in arithmetic expressions.
2690 * Chars:: Characters
2694 @subsubsection Strings
2696 @cindex string constants
2697 @cindex constants, string
2698 A @dfn{string} is written between double-quotes. It may contain
2699 double-quotes or null characters. The way to get special characters
2700 into a string is to @dfn{escape} these characters: precede them with
2701 a backslash @samp{\} character. For example @samp{\\} represents
2702 one backslash: the first @code{\} is an escape which tells
2703 @command{@value{AS}} to interpret the second character literally as a backslash
2704 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2705 escape character). The complete list of escapes follows.
2707 @cindex escape codes, character
2708 @cindex character escape codes
2711 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2713 @cindex @code{\b} (backspace character)
2714 @cindex backspace (@code{\b})
2716 Mnemonic for backspace; for ASCII this is octal code 010.
2719 @c Mnemonic for EOText; for ASCII this is octal code 004.
2721 @cindex @code{\f} (formfeed character)
2722 @cindex formfeed (@code{\f})
2724 Mnemonic for FormFeed; for ASCII this is octal code 014.
2726 @cindex @code{\n} (newline character)
2727 @cindex newline (@code{\n})
2729 Mnemonic for newline; for ASCII this is octal code 012.
2732 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2734 @cindex @code{\r} (carriage return character)
2735 @cindex carriage return (@code{\r})
2737 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2740 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2741 @c other assemblers.
2743 @cindex @code{\t} (tab)
2744 @cindex tab (@code{\t})
2746 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2749 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2750 @c @item \x @var{digit} @var{digit} @var{digit}
2751 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2753 @cindex @code{\@var{ddd}} (octal character code)
2754 @cindex octal character code (@code{\@var{ddd}})
2755 @item \ @var{digit} @var{digit} @var{digit}
2756 An octal character code. The numeric code is 3 octal digits.
2757 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2758 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2760 @cindex @code{\@var{xd...}} (hex character code)
2761 @cindex hex character code (@code{\@var{xd...}})
2762 @item \@code{x} @var{hex-digits...}
2763 A hex character code. All trailing hex digits are combined. Either upper or
2764 lower case @code{x} works.
2766 @cindex @code{\\} (@samp{\} character)
2767 @cindex backslash (@code{\\})
2769 Represents one @samp{\} character.
2772 @c Represents one @samp{'} (accent acute) character.
2773 @c This is needed in single character literals
2774 @c (@xref{Characters,,Character Constants}.) to represent
2777 @cindex @code{\"} (doublequote character)
2778 @cindex doublequote (@code{\"})
2780 Represents one @samp{"} character. Needed in strings to represent
2781 this character, because an unescaped @samp{"} would end the string.
2783 @item \ @var{anything-else}
2784 Any other character when escaped by @kbd{\} gives a warning, but
2785 assembles as if the @samp{\} was not present. The idea is that if
2786 you used an escape sequence you clearly didn't want the literal
2787 interpretation of the following character. However @command{@value{AS}} has no
2788 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2789 code and warns you of the fact.
2792 Which characters are escapable, and what those escapes represent,
2793 varies widely among assemblers. The current set is what we think
2794 the BSD 4.2 assembler recognizes, and is a subset of what most C
2795 compilers recognize. If you are in doubt, do not use an escape
2799 @subsubsection Characters
2801 @cindex single character constant
2802 @cindex character, single
2803 @cindex constant, single character
2804 A single character may be written as a single quote immediately
2805 followed by that character. The same escapes apply to characters as
2806 to strings. So if you want to write the character backslash, you
2807 must write @kbd{'\\} where the first @code{\} escapes the second
2808 @code{\}. As you can see, the quote is an acute accent, not a
2809 grave accent. A newline
2811 @ifclear abnormal-separator
2812 (or semicolon @samp{;})
2814 @ifset abnormal-separator
2816 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2821 immediately following an acute accent is taken as a literal character
2822 and does not count as the end of a statement. The value of a character
2823 constant in a numeric expression is the machine's byte-wide code for
2824 that character. @command{@value{AS}} assumes your character code is ASCII:
2825 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2828 @subsection Number Constants
2830 @cindex constants, number
2831 @cindex number constants
2832 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2833 are stored in the target machine. @emph{Integers} are numbers that
2834 would fit into an @code{int} in the C language. @emph{Bignums} are
2835 integers, but they are stored in more than 32 bits. @emph{Flonums}
2836 are floating point numbers, described below.
2839 * Integers:: Integers
2844 * Bit Fields:: Bit Fields
2850 @subsubsection Integers
2852 @cindex constants, integer
2854 @cindex binary integers
2855 @cindex integers, binary
2856 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2857 the binary digits @samp{01}.
2859 @cindex octal integers
2860 @cindex integers, octal
2861 An octal integer is @samp{0} followed by zero or more of the octal
2862 digits (@samp{01234567}).
2864 @cindex decimal integers
2865 @cindex integers, decimal
2866 A decimal integer starts with a non-zero digit followed by zero or
2867 more digits (@samp{0123456789}).
2869 @cindex hexadecimal integers
2870 @cindex integers, hexadecimal
2871 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2872 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2874 Integers have the usual values. To denote a negative integer, use
2875 the prefix operator @samp{-} discussed under expressions
2876 (@pxref{Prefix Ops,,Prefix Operators}).
2879 @subsubsection Bignums
2882 @cindex constants, bignum
2883 A @dfn{bignum} has the same syntax and semantics as an integer
2884 except that the number (or its negative) takes more than 32 bits to
2885 represent in binary. The distinction is made because in some places
2886 integers are permitted while bignums are not.
2889 @subsubsection Flonums
2891 @cindex floating point numbers
2892 @cindex constants, floating point
2894 @cindex precision, floating point
2895 A @dfn{flonum} represents a floating point number. The translation is
2896 indirect: a decimal floating point number from the text is converted by
2897 @command{@value{AS}} to a generic binary floating point number of more than
2898 sufficient precision. This generic floating point number is converted
2899 to a particular computer's floating point format (or formats) by a
2900 portion of @command{@value{AS}} specialized to that computer.
2902 A flonum is written by writing (in order)
2907 (@samp{0} is optional on the HPPA.)
2911 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2913 @kbd{e} is recommended. Case is not important.
2915 @c FIXME: verify if flonum syntax really this vague for most cases
2916 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2917 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2920 On the H8/300, Renesas / SuperH SH,
2921 and AMD 29K architectures, the letter must be
2922 one of the letters @samp{DFPRSX} (in upper or lower case).
2924 On the ARC, the letter must be one of the letters @samp{DFRS}
2925 (in upper or lower case).
2927 On the Intel 960 architecture, the letter must be
2928 one of the letters @samp{DFT} (in upper or lower case).
2930 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2934 One of the letters @samp{DFRS} (in upper or lower case).
2937 One of the letters @samp{DFPRSX} (in upper or lower case).
2940 The letter @samp{E} (upper case only).
2943 One of the letters @samp{DFT} (in upper or lower case).
2948 An optional sign: either @samp{+} or @samp{-}.
2951 An optional @dfn{integer part}: zero or more decimal digits.
2954 An optional @dfn{fractional part}: @samp{.} followed by zero
2955 or more decimal digits.
2958 An optional exponent, consisting of:
2962 An @samp{E} or @samp{e}.
2963 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2964 @c principle this can perfectly well be different on different targets.
2966 Optional sign: either @samp{+} or @samp{-}.
2968 One or more decimal digits.
2973 At least one of the integer part or the fractional part must be
2974 present. The floating point number has the usual base-10 value.
2976 @command{@value{AS}} does all processing using integers. Flonums are computed
2977 independently of any floating point hardware in the computer running
2978 @command{@value{AS}}.
2982 @c Bit fields are written as a general facility but are also controlled
2983 @c by a conditional-compilation flag---which is as of now (21mar91)
2984 @c turned on only by the i960 config of GAS.
2986 @subsubsection Bit Fields
2989 @cindex constants, bit field
2990 You can also define numeric constants as @dfn{bit fields}.
2991 Specify two numbers separated by a colon---
2993 @var{mask}:@var{value}
2996 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2999 The resulting number is then packed
3001 @c this conditional paren in case bit fields turned on elsewhere than 960
3002 (in host-dependent byte order)
3004 into a field whose width depends on which assembler directive has the
3005 bit-field as its argument. Overflow (a result from the bitwise and
3006 requiring more binary digits to represent) is not an error; instead,
3007 more constants are generated, of the specified width, beginning with the
3008 least significant digits.@refill
3010 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
3011 @code{.short}, and @code{.word} accept bit-field arguments.
3016 @chapter Sections and Relocation
3021 * Secs Background:: Background
3022 * Ld Sections:: Linker Sections
3023 * As Sections:: Assembler Internal Sections
3024 * Sub-Sections:: Sub-Sections
3028 @node Secs Background
3031 Roughly, a section is a range of addresses, with no gaps; all data
3032 ``in'' those addresses is treated the same for some particular purpose.
3033 For example there may be a ``read only'' section.
3035 @cindex linker, and assembler
3036 @cindex assembler, and linker
3037 The linker @code{@value{LD}} reads many object files (partial programs) and
3038 combines their contents to form a runnable program. When @command{@value{AS}}
3039 emits an object file, the partial program is assumed to start at address 0.
3040 @code{@value{LD}} assigns the final addresses for the partial program, so that
3041 different partial programs do not overlap. This is actually an
3042 oversimplification, but it suffices to explain how @command{@value{AS}} uses
3045 @code{@value{LD}} moves blocks of bytes of your program to their run-time
3046 addresses. These blocks slide to their run-time addresses as rigid
3047 units; their length does not change and neither does the order of bytes
3048 within them. Such a rigid unit is called a @emph{section}. Assigning
3049 run-time addresses to sections is called @dfn{relocation}. It includes
3050 the task of adjusting mentions of object-file addresses so they refer to
3051 the proper run-time addresses.
3053 For the H8/300, and for the Renesas / SuperH SH,
3054 @command{@value{AS}} pads sections if needed to
3055 ensure they end on a word (sixteen bit) boundary.
3058 @cindex standard assembler sections
3059 An object file written by @command{@value{AS}} has at least three sections, any
3060 of which may be empty. These are named @dfn{text}, @dfn{data} and
3065 When it generates COFF or ELF output,
3067 @command{@value{AS}} can also generate whatever other named sections you specify
3068 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
3069 If you do not use any directives that place output in the @samp{.text}
3070 or @samp{.data} sections, these sections still exist, but are empty.
3075 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
3077 @command{@value{AS}} can also generate whatever other named sections you
3078 specify using the @samp{.space} and @samp{.subspace} directives. See
3079 @cite{HP9000 Series 800 Assembly Language Reference Manual}
3080 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
3081 assembler directives.
3084 Additionally, @command{@value{AS}} uses different names for the standard
3085 text, data, and bss sections when generating SOM output. Program text
3086 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
3087 BSS into @samp{$BSS$}.
3091 Within the object file, the text section starts at address @code{0}, the
3092 data section follows, and the bss section follows the data section.
3095 When generating either SOM or ELF output files on the HPPA, the text
3096 section starts at address @code{0}, the data section at address
3097 @code{0x4000000}, and the bss section follows the data section.
3100 To let @code{@value{LD}} know which data changes when the sections are
3101 relocated, and how to change that data, @command{@value{AS}} also writes to the
3102 object file details of the relocation needed. To perform relocation
3103 @code{@value{LD}} must know, each time an address in the object
3107 Where in the object file is the beginning of this reference to
3110 How long (in bytes) is this reference?
3112 Which section does the address refer to? What is the numeric value of
3114 (@var{address}) @minus{} (@var{start-address of section})?
3117 Is the reference to an address ``Program-Counter relative''?
3120 @cindex addresses, format of
3121 @cindex section-relative addressing
3122 In fact, every address @command{@value{AS}} ever uses is expressed as
3124 (@var{section}) + (@var{offset into section})
3127 Further, most expressions @command{@value{AS}} computes have this section-relative
3130 (For some object formats, such as SOM for the HPPA, some expressions are
3131 symbol-relative instead.)
3134 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
3135 @var{N} into section @var{secname}.''
3137 Apart from text, data and bss sections you need to know about the
3138 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
3139 addresses in the absolute section remain unchanged. For example, address
3140 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
3141 @code{@value{LD}}. Although the linker never arranges two partial programs'
3142 data sections with overlapping addresses after linking, @emph{by definition}
3143 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
3144 part of a program is always the same address when the program is running as
3145 address @code{@{absolute@ 239@}} in any other part of the program.
3147 The idea of sections is extended to the @dfn{undefined} section. Any
3148 address whose section is unknown at assembly time is by definition
3149 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
3150 Since numbers are always defined, the only way to generate an undefined
3151 address is to mention an undefined symbol. A reference to a named
3152 common block would be such a symbol: its value is unknown at assembly
3153 time so it has section @emph{undefined}.
3155 By analogy the word @emph{section} is used to describe groups of sections in
3156 the linked program. @code{@value{LD}} puts all partial programs' text
3157 sections in contiguous addresses in the linked program. It is
3158 customary to refer to the @emph{text section} of a program, meaning all
3159 the addresses of all partial programs' text sections. Likewise for
3160 data and bss sections.
3162 Some sections are manipulated by @code{@value{LD}}; others are invented for
3163 use of @command{@value{AS}} and have no meaning except during assembly.
3166 @section Linker Sections
3167 @code{@value{LD}} deals with just four kinds of sections, summarized below.
3172 @cindex named sections
3173 @cindex sections, named
3174 @item named sections
3177 @cindex text section
3178 @cindex data section
3182 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
3183 separate but equal sections. Anything you can say of one section is
3186 When the program is running, however, it is
3187 customary for the text section to be unalterable. The
3188 text section is often shared among processes: it contains
3189 instructions, constants and the like. The data section of a running
3190 program is usually alterable: for example, C variables would be stored
3191 in the data section.
3196 This section contains zeroed bytes when your program begins running. It
3197 is used to hold uninitialized variables or common storage. The length of
3198 each partial program's bss section is important, but because it starts
3199 out containing zeroed bytes there is no need to store explicit zero
3200 bytes in the object file. The bss section was invented to eliminate
3201 those explicit zeros from object files.
3203 @cindex absolute section
3204 @item absolute section
3205 Address 0 of this section is always ``relocated'' to runtime address 0.
3206 This is useful if you want to refer to an address that @code{@value{LD}} must
3207 not change when relocating. In this sense we speak of absolute
3208 addresses being ``unrelocatable'': they do not change during relocation.
3210 @cindex undefined section
3211 @item undefined section
3212 This ``section'' is a catch-all for address references to objects not in
3213 the preceding sections.
3214 @c FIXME: ref to some other doc on obj-file formats could go here.
3217 @cindex relocation example
3218 An idealized example of three relocatable sections follows.
3220 The example uses the traditional section names @samp{.text} and @samp{.data}.
3222 Memory addresses are on the horizontal axis.
3226 @c END TEXI2ROFF-KILL
3229 partial program # 1: |ttttt|dddd|00|
3236 partial program # 2: |TTT|DDD|000|
3239 +--+---+-----+--+----+---+-----+~~
3240 linked program: | |TTT|ttttt| |dddd|DDD|00000|
3241 +--+---+-----+--+----+---+-----+~~
3243 addresses: 0 @dots{}
3250 \line{\it Partial program \#1: \hfil}
3251 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3252 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
3254 \line{\it Partial program \#2: \hfil}
3255 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3256 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
3258 \line{\it linked program: \hfil}
3259 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
3260 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
3261 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
3262 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
3264 \line{\it addresses: \hfil}
3268 @c END TEXI2ROFF-KILL
3271 @section Assembler Internal Sections
3273 @cindex internal assembler sections
3274 @cindex sections in messages, internal
3275 These sections are meant only for the internal use of @command{@value{AS}}. They
3276 have no meaning at run-time. You do not really need to know about these
3277 sections for most purposes; but they can be mentioned in @command{@value{AS}}
3278 warning messages, so it might be helpful to have an idea of their
3279 meanings to @command{@value{AS}}. These sections are used to permit the
3280 value of every expression in your assembly language program to be a
3281 section-relative address.
3284 @cindex assembler internal logic error
3285 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
3286 An internal assembler logic error has been found. This means there is a
3287 bug in the assembler.
3289 @cindex expr (internal section)
3291 The assembler stores complex expression internally as combinations of
3292 symbols. When it needs to represent an expression as a symbol, it puts
3293 it in the expr section.
3295 @c FIXME item transfer[t] vector preload
3296 @c FIXME item transfer[t] vector postload
3297 @c FIXME item register
3301 @section Sub-Sections
3303 @cindex numbered subsections
3304 @cindex grouping data
3310 fall into two sections: text and data.
3312 You may have separate groups of
3314 data in named sections
3318 data in named sections
3324 that you want to end up near to each other in the object file, even though they
3325 are not contiguous in the assembler source. @command{@value{AS}} allows you to
3326 use @dfn{subsections} for this purpose. Within each section, there can be
3327 numbered subsections with values from 0 to 8192. Objects assembled into the
3328 same subsection go into the object file together with other objects in the same
3329 subsection. For example, a compiler might want to store constants in the text
3330 section, but might not want to have them interspersed with the program being
3331 assembled. In this case, the compiler could issue a @samp{.text 0} before each
3332 section of code being output, and a @samp{.text 1} before each group of
3333 constants being output.
3335 Subsections are optional. If you do not use subsections, everything
3336 goes in subsection number zero.
3339 Each subsection is zero-padded up to a multiple of four bytes.
3340 (Subsections may be padded a different amount on different flavors
3341 of @command{@value{AS}}.)
3345 On the H8/300 platform, each subsection is zero-padded to a word
3346 boundary (two bytes).
3347 The same is true on the Renesas SH.
3350 @c FIXME section padding (alignment)?
3351 @c Rich Pixley says padding here depends on target obj code format; that
3352 @c doesn't seem particularly useful to say without further elaboration,
3353 @c so for now I say nothing about it. If this is a generic BFD issue,
3354 @c these paragraphs might need to vanish from this manual, and be
3355 @c discussed in BFD chapter of binutils (or some such).
3359 Subsections appear in your object file in numeric order, lowest numbered
3360 to highest. (All this to be compatible with other people's assemblers.)
3361 The object file contains no representation of subsections; @code{@value{LD}} and
3362 other programs that manipulate object files see no trace of them.
3363 They just see all your text subsections as a text section, and all your
3364 data subsections as a data section.
3366 To specify which subsection you want subsequent statements assembled
3367 into, use a numeric argument to specify it, in a @samp{.text
3368 @var{expression}} or a @samp{.data @var{expression}} statement.
3371 When generating COFF output, you
3376 can also use an extra subsection
3377 argument with arbitrary named sections: @samp{.section @var{name},
3382 When generating ELF output, you
3387 can also use the @code{.subsection} directive (@pxref{SubSection})
3388 to specify a subsection: @samp{.subsection @var{expression}}.
3390 @var{Expression} should be an absolute expression
3391 (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0}
3392 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3393 begins in @code{text 0}. For instance:
3395 .text 0 # The default subsection is text 0 anyway.
3396 .ascii "This lives in the first text subsection. *"
3398 .ascii "But this lives in the second text subsection."
3400 .ascii "This lives in the data section,"
3401 .ascii "in the first data subsection."
3403 .ascii "This lives in the first text section,"
3404 .ascii "immediately following the asterisk (*)."
3407 Each section has a @dfn{location counter} incremented by one for every byte
3408 assembled into that section. Because subsections are merely a convenience
3409 restricted to @command{@value{AS}} there is no concept of a subsection location
3410 counter. There is no way to directly manipulate a location counter---but the
3411 @code{.align} directive changes it, and any label definition captures its
3412 current value. The location counter of the section where statements are being
3413 assembled is said to be the @dfn{active} location counter.
3416 @section bss Section
3419 @cindex common variable storage
3420 The bss section is used for local common variable storage.
3421 You may allocate address space in the bss section, but you may
3422 not dictate data to load into it before your program executes. When
3423 your program starts running, all the contents of the bss
3424 section are zeroed bytes.
3426 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3427 @ref{Lcomm,,@code{.lcomm}}.
3429 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3430 another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}.
3433 When assembling for a target which supports multiple sections, such as ELF or
3434 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3435 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3436 section. Typically the section will only contain symbol definitions and
3437 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3444 Symbols are a central concept: the programmer uses symbols to name
3445 things, the linker uses symbols to link, and the debugger uses symbols
3449 @cindex debuggers, and symbol order
3450 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3451 the same order they were declared. This may break some debuggers.
3456 * Setting Symbols:: Giving Symbols Other Values
3457 * Symbol Names:: Symbol Names
3458 * Dot:: The Special Dot Symbol
3459 * Symbol Attributes:: Symbol Attributes
3466 A @dfn{label} is written as a symbol immediately followed by a colon
3467 @samp{:}. The symbol then represents the current value of the
3468 active location counter, and is, for example, a suitable instruction
3469 operand. You are warned if you use the same symbol to represent two
3470 different locations: the first definition overrides any other
3474 On the HPPA, the usual form for a label need not be immediately followed by a
3475 colon, but instead must start in column zero. Only one label may be defined on
3476 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3477 provides a special directive @code{.label} for defining labels more flexibly.
3480 @node Setting Symbols
3481 @section Giving Symbols Other Values
3483 @cindex assigning values to symbols
3484 @cindex symbol values, assigning
3485 A symbol can be given an arbitrary value by writing a symbol, followed
3486 by an equals sign @samp{=}, followed by an expression
3487 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3488 directive. @xref{Set,,@code{.set}}. In the same way, using a double
3489 equals sign @samp{=}@samp{=} here represents an equivalent of the
3490 @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}.
3493 Blackfin does not support symbol assignment with @samp{=}.
3497 @section Symbol Names
3499 @cindex symbol names
3500 @cindex names, symbol
3501 @ifclear SPECIAL-SYMS
3502 Symbol names begin with a letter or with one of @samp{._}. On most
3503 machines, you can also use @code{$} in symbol names; exceptions are
3504 noted in @ref{Machine Dependencies}. That character may be followed by any
3505 string of digits, letters, dollar signs (unless otherwise noted for a
3506 particular target machine), and underscores.
3510 Symbol names begin with a letter or with one of @samp{._}. On the
3511 Renesas SH you can also use @code{$} in symbol names. That
3512 character may be followed by any string of digits, letters, dollar signs (save
3513 on the H8/300), and underscores.
3517 Case of letters is significant: @code{foo} is a different symbol name
3520 Multibyte characters are supported. To generate a symbol name containing
3521 multibyte characters enclose it within double quotes and use escape codes. cf
3522 @xref{Strings}. Generating a multibyte symbol name from a label is not
3523 currently supported.
3525 Each symbol has exactly one name. Each name in an assembly language program
3526 refers to exactly one symbol. You may use that symbol name any number of times
3529 @subheading Local Symbol Names
3531 @cindex local symbol names
3532 @cindex symbol names, local
3533 A local symbol is any symbol beginning with certain local label prefixes.
3534 By default, the local label prefix is @samp{.L} for ELF systems or
3535 @samp{L} for traditional a.out systems, but each target may have its own
3536 set of local label prefixes.
3538 On the HPPA local symbols begin with @samp{L$}.
3541 Local symbols are defined and used within the assembler, but they are
3542 normally not saved in object files. Thus, they are not visible when debugging.
3543 You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols:
3544 @option{-L}}) to retain the local symbols in the object files.
3546 @subheading Local Labels
3548 @cindex local labels
3549 @cindex temporary symbol names
3550 @cindex symbol names, temporary
3551 Local labels help compilers and programmers use names temporarily.
3552 They create symbols which are guaranteed to be unique over the entire scope of
3553 the input source code and which can be referred to by a simple notation.
3554 To define a local label, write a label of the form @samp{@b{N}:} (where @b{N}
3555 represents any positive integer). To refer to the most recent previous
3556 definition of that label write @samp{@b{N}b}, using the same number as when
3557 you defined the label. To refer to the next definition of a local label, write
3558 @samp{@b{N}f}---the @samp{b} stands for ``backwards'' and the @samp{f} stands
3561 There is no restriction on how you can use these labels, and you can reuse them
3562 too. So that it is possible to repeatedly define the same local label (using
3563 the same number @samp{@b{N}}), although you can only refer to the most recently
3564 defined local label of that number (for a backwards reference) or the next
3565 definition of a specific local label for a forward reference. It is also worth
3566 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3567 implemented in a slightly more efficient manner than the others.
3578 Which is the equivalent of:
3581 label_1: branch label_3
3582 label_2: branch label_1
3583 label_3: branch label_4
3584 label_4: branch label_3
3587 Local label names are only a notational device. They are immediately
3588 transformed into more conventional symbol names before the assembler uses them.
3589 The symbol names are stored in the symbol table, appear in error messages, and
3590 are optionally emitted to the object file. The names are constructed using
3594 @item @emph{local label prefix}
3595 All local symbols begin with the system-specific local label prefix.
3596 Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols
3597 that start with the local label prefix. These labels are
3598 used for symbols you are never intended to see. If you use the
3599 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3600 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3601 you may use them in debugging.
3604 This is the number that was used in the local label definition. So if the
3605 label is written @samp{55:} then the number is @samp{55}.
3608 This unusual character is included so you do not accidentally invent a symbol
3609 of the same name. The character has ASCII value of @samp{\002} (control-B).
3611 @item @emph{ordinal number}
3612 This is a serial number to keep the labels distinct. The first definition of
3613 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3614 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3615 the number @samp{1} and its 15th definition gets @samp{15} as well.
3618 So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and
3619 the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}.
3621 @subheading Dollar Local Labels
3622 @cindex dollar local symbols
3624 @code{@value{AS}} also supports an even more local form of local labels called
3625 dollar labels. These labels go out of scope (i.e., they become undefined) as
3626 soon as a non-local label is defined. Thus they remain valid for only a small
3627 region of the input source code. Normal local labels, by contrast, remain in
3628 scope for the entire file, or until they are redefined by another occurrence of
3629 the same local label.
3631 Dollar labels are defined in exactly the same way as ordinary local labels,
3632 except that they have a dollar sign suffix to their numeric value, e.g.,
3635 They can also be distinguished from ordinary local labels by their transformed
3636 names which use ASCII character @samp{\001} (control-A) as the magic character
3637 to distinguish them from ordinary labels. For example, the fifth definition of
3638 @samp{6$} may be named @samp{.L6@kbd{C-A}5}.
3641 @section The Special Dot Symbol
3643 @cindex dot (symbol)
3644 @cindex @code{.} (symbol)
3645 @cindex current address
3646 @cindex location counter
3647 The special symbol @samp{.} refers to the current address that
3648 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3649 .long .} defines @code{melvin} to contain its own address.
3650 Assigning a value to @code{.} is treated the same as a @code{.org}
3652 @ifclear no-space-dir
3653 Thus, the expression @samp{.=.+4} is the same as saying
3657 @node Symbol Attributes
3658 @section Symbol Attributes
3660 @cindex symbol attributes
3661 @cindex attributes, symbol
3662 Every symbol has, as well as its name, the attributes ``Value'' and
3663 ``Type''. Depending on output format, symbols can also have auxiliary
3666 The detailed definitions are in @file{a.out.h}.
3669 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3670 all these attributes, and probably won't warn you. This makes the
3671 symbol an externally defined symbol, which is generally what you
3675 * Symbol Value:: Value
3676 * Symbol Type:: Type
3679 * a.out Symbols:: Symbol Attributes: @code{a.out}
3683 * a.out Symbols:: Symbol Attributes: @code{a.out}
3686 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3691 * COFF Symbols:: Symbol Attributes for COFF
3694 * SOM Symbols:: Symbol Attributes for SOM
3701 @cindex value of a symbol
3702 @cindex symbol value
3703 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3704 location in the text, data, bss or absolute sections the value is the
3705 number of addresses from the start of that section to the label.
3706 Naturally for text, data and bss sections the value of a symbol changes
3707 as @code{@value{LD}} changes section base addresses during linking. Absolute
3708 symbols' values do not change during linking: that is why they are
3711 The value of an undefined symbol is treated in a special way. If it is
3712 0 then the symbol is not defined in this assembler source file, and
3713 @code{@value{LD}} tries to determine its value from other files linked into the
3714 same program. You make this kind of symbol simply by mentioning a symbol
3715 name without defining it. A non-zero value represents a @code{.comm}
3716 common declaration. The value is how much common storage to reserve, in
3717 bytes (addresses). The symbol refers to the first address of the
3723 @cindex type of a symbol
3725 The type attribute of a symbol contains relocation (section)
3726 information, any flag settings indicating that a symbol is external, and
3727 (optionally), other information for linkers and debuggers. The exact
3728 format depends on the object-code output format in use.
3733 @c The following avoids a "widow" subsection title. @group would be
3734 @c better if it were available outside examples.
3737 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3739 @cindex @code{b.out} symbol attributes
3740 @cindex symbol attributes, @code{b.out}
3741 These symbol attributes appear only when @command{@value{AS}} is configured for
3742 one of the Berkeley-descended object output formats---@code{a.out} or
3748 @subsection Symbol Attributes: @code{a.out}
3750 @cindex @code{a.out} symbol attributes
3751 @cindex symbol attributes, @code{a.out}
3757 @subsection Symbol Attributes: @code{a.out}
3759 @cindex @code{a.out} symbol attributes
3760 @cindex symbol attributes, @code{a.out}
3764 * Symbol Desc:: Descriptor
3765 * Symbol Other:: Other
3769 @subsubsection Descriptor
3771 @cindex descriptor, of @code{a.out} symbol
3772 This is an arbitrary 16-bit value. You may establish a symbol's
3773 descriptor value by using a @code{.desc} statement
3774 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3775 @command{@value{AS}}.
3778 @subsubsection Other
3780 @cindex other attribute, of @code{a.out} symbol
3781 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3786 @subsection Symbol Attributes for COFF
3788 @cindex COFF symbol attributes
3789 @cindex symbol attributes, COFF
3791 The COFF format supports a multitude of auxiliary symbol attributes;
3792 like the primary symbol attributes, they are set between @code{.def} and
3793 @code{.endef} directives.
3795 @subsubsection Primary Attributes
3797 @cindex primary attributes, COFF symbols
3798 The symbol name is set with @code{.def}; the value and type,
3799 respectively, with @code{.val} and @code{.type}.
3801 @subsubsection Auxiliary Attributes
3803 @cindex auxiliary attributes, COFF symbols
3804 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3805 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3806 table information for COFF.
3811 @subsection Symbol Attributes for SOM
3813 @cindex SOM symbol attributes
3814 @cindex symbol attributes, SOM
3816 The SOM format for the HPPA supports a multitude of symbol attributes set with
3817 the @code{.EXPORT} and @code{.IMPORT} directives.
3819 The attributes are described in @cite{HP9000 Series 800 Assembly
3820 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3821 @code{EXPORT} assembler directive documentation.
3825 @chapter Expressions
3829 @cindex numeric values
3830 An @dfn{expression} specifies an address or numeric value.
3831 Whitespace may precede and/or follow an expression.
3833 The result of an expression must be an absolute number, or else an offset into
3834 a particular section. If an expression is not absolute, and there is not
3835 enough information when @command{@value{AS}} sees the expression to know its
3836 section, a second pass over the source program might be necessary to interpret
3837 the expression---but the second pass is currently not implemented.
3838 @command{@value{AS}} aborts with an error message in this situation.
3841 * Empty Exprs:: Empty Expressions
3842 * Integer Exprs:: Integer Expressions
3846 @section Empty Expressions
3848 @cindex empty expressions
3849 @cindex expressions, empty
3850 An empty expression has no value: it is just whitespace or null.
3851 Wherever an absolute expression is required, you may omit the
3852 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3853 is compatible with other assemblers.
3856 @section Integer Expressions
3858 @cindex integer expressions
3859 @cindex expressions, integer
3860 An @dfn{integer expression} is one or more @emph{arguments} delimited
3861 by @emph{operators}.
3864 * Arguments:: Arguments
3865 * Operators:: Operators
3866 * Prefix Ops:: Prefix Operators
3867 * Infix Ops:: Infix Operators
3871 @subsection Arguments
3873 @cindex expression arguments
3874 @cindex arguments in expressions
3875 @cindex operands in expressions
3876 @cindex arithmetic operands
3877 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3878 contexts arguments are sometimes called ``arithmetic operands''. In
3879 this manual, to avoid confusing them with the ``instruction operands'' of
3880 the machine language, we use the term ``argument'' to refer to parts of
3881 expressions only, reserving the word ``operand'' to refer only to machine
3882 instruction operands.
3884 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3885 @var{section} is one of text, data, bss, absolute,
3886 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3889 Numbers are usually integers.
3891 A number can be a flonum or bignum. In this case, you are warned
3892 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3893 these 32 bits are an integer. You may write integer-manipulating
3894 instructions that act on exotic constants, compatible with other
3897 @cindex subexpressions
3898 Subexpressions are a left parenthesis @samp{(} followed by an integer
3899 expression, followed by a right parenthesis @samp{)}; or a prefix
3900 operator followed by an argument.
3903 @subsection Operators
3905 @cindex operators, in expressions
3906 @cindex arithmetic functions
3907 @cindex functions, in expressions
3908 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3909 operators are followed by an argument. Infix operators appear
3910 between their arguments. Operators may be preceded and/or followed by
3914 @subsection Prefix Operator
3916 @cindex prefix operators
3917 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3918 one argument, which must be absolute.
3920 @c the tex/end tex stuff surrounding this small table is meant to make
3921 @c it align, on the printed page, with the similar table in the next
3922 @c section (which is inside an enumerate).
3924 \global\advance\leftskip by \itemindent
3929 @dfn{Negation}. Two's complement negation.
3931 @dfn{Complementation}. Bitwise not.
3935 \global\advance\leftskip by -\itemindent
3939 @subsection Infix Operators
3941 @cindex infix operators
3942 @cindex operators, permitted arguments
3943 @dfn{Infix operators} take two arguments, one on either side. Operators
3944 have precedence, but operations with equal precedence are performed left
3945 to right. Apart from @code{+} or @option{-}, both arguments must be
3946 absolute, and the result is absolute.
3949 @cindex operator precedence
3950 @cindex precedence of operators
3957 @dfn{Multiplication}.
3960 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3966 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3969 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3973 Intermediate precedence
3978 @dfn{Bitwise Inclusive Or}.
3984 @dfn{Bitwise Exclusive Or}.
3987 @dfn{Bitwise Or Not}.
3994 @cindex addition, permitted arguments
3995 @cindex plus, permitted arguments
3996 @cindex arguments for addition
3998 @dfn{Addition}. If either argument is absolute, the result has the section of
3999 the other argument. You may not add together arguments from different
4002 @cindex subtraction, permitted arguments
4003 @cindex minus, permitted arguments
4004 @cindex arguments for subtraction
4006 @dfn{Subtraction}. If the right argument is absolute, the
4007 result has the section of the left argument.
4008 If both arguments are in the same section, the result is absolute.
4009 You may not subtract arguments from different sections.
4010 @c FIXME is there still something useful to say about undefined - undefined ?
4012 @cindex comparison expressions
4013 @cindex expressions, comparison
4018 @dfn{Is Not Equal To}
4022 @dfn{Is Greater Than}
4024 @dfn{Is Greater Than Or Equal To}
4026 @dfn{Is Less Than Or Equal To}
4028 The comparison operators can be used as infix operators. A true results has a
4029 value of -1 whereas a false result has a value of 0. Note, these operators
4030 perform signed comparisons.
4033 @item Lowest Precedence
4042 These two logical operations can be used to combine the results of sub
4043 expressions. Note, unlike the comparison operators a true result returns a
4044 value of 1 but a false results does still return 0. Also note that the logical
4045 or operator has a slightly lower precedence than logical and.
4050 In short, it's only meaningful to add or subtract the @emph{offsets} in an
4051 address; you can only have a defined section in one of the two arguments.
4054 @chapter Assembler Directives
4056 @cindex directives, machine independent
4057 @cindex pseudo-ops, machine independent
4058 @cindex machine independent directives
4059 All assembler directives have names that begin with a period (@samp{.}).
4060 The rest of the name is letters, usually in lower case.
4062 This chapter discusses directives that are available regardless of the
4063 target machine configuration for the @sc{gnu} assembler.
4065 Some machine configurations provide additional directives.
4066 @xref{Machine Dependencies}.
4069 @ifset machine-directives
4070 @xref{Machine Dependencies}, for additional directives.
4075 * Abort:: @code{.abort}
4077 * ABORT (COFF):: @code{.ABORT}
4080 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
4081 * Altmacro:: @code{.altmacro}
4082 * Ascii:: @code{.ascii "@var{string}"}@dots{}
4083 * Asciz:: @code{.asciz "@var{string}"}@dots{}
4084 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
4085 * Bundle directives:: @code{.bundle_align_mode @var{abs-expr}}, @code{.bundle_lock}, @code{.bundle_unlock}
4086 * Byte:: @code{.byte @var{expressions}}
4087 * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
4088 * Comm:: @code{.comm @var{symbol} , @var{length} }
4089 * Data:: @code{.data @var{subsection}}
4091 * Def:: @code{.def @var{name}}
4094 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
4100 * Double:: @code{.double @var{flonums}}
4101 * Eject:: @code{.eject}
4102 * Else:: @code{.else}
4103 * Elseif:: @code{.elseif}
4106 * Endef:: @code{.endef}
4109 * Endfunc:: @code{.endfunc}
4110 * Endif:: @code{.endif}
4111 * Equ:: @code{.equ @var{symbol}, @var{expression}}
4112 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
4113 * Eqv:: @code{.eqv @var{symbol}, @var{expression}}
4115 * Error:: @code{.error @var{string}}
4116 * Exitm:: @code{.exitm}
4117 * Extern:: @code{.extern}
4118 * Fail:: @code{.fail}
4119 * File:: @code{.file}
4120 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
4121 * Float:: @code{.float @var{flonums}}
4122 * Func:: @code{.func}
4123 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4125 * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
4126 * Hidden:: @code{.hidden @var{names}}
4129 * hword:: @code{.hword @var{expressions}}
4130 * Ident:: @code{.ident}
4131 * If:: @code{.if @var{absolute expression}}
4132 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4133 * Include:: @code{.include "@var{file}"}
4134 * Int:: @code{.int @var{expressions}}
4136 * Internal:: @code{.internal @var{names}}
4139 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
4140 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
4141 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
4142 * Lflags:: @code{.lflags}
4143 @ifclear no-line-dir
4144 * Line:: @code{.line @var{line-number}}
4147 * Linkonce:: @code{.linkonce [@var{type}]}
4148 * List:: @code{.list}
4149 * Ln:: @code{.ln @var{line-number}}
4150 * Loc:: @code{.loc @var{fileno} @var{lineno}}
4151 * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}}
4153 * Local:: @code{.local @var{names}}
4156 * Long:: @code{.long @var{expressions}}
4158 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
4161 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
4162 * MRI:: @code{.mri @var{val}}
4163 * Noaltmacro:: @code{.noaltmacro}
4164 * Nolist:: @code{.nolist}
4165 * Octa:: @code{.octa @var{bignums}}
4166 * Offset:: @code{.offset @var{loc}}
4167 * Org:: @code{.org @var{new-lc}, @var{fill}}
4168 * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4170 * PopSection:: @code{.popsection}
4171 * Previous:: @code{.previous}
4174 * Print:: @code{.print @var{string}}
4176 * Protected:: @code{.protected @var{names}}
4179 * Psize:: @code{.psize @var{lines}, @var{columns}}
4180 * Purgem:: @code{.purgem @var{name}}
4182 * PushSection:: @code{.pushsection @var{name}}
4185 * Quad:: @code{.quad @var{bignums}}
4186 * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
4187 * Rept:: @code{.rept @var{count}}
4188 * Sbttl:: @code{.sbttl "@var{subheading}"}
4190 * Scl:: @code{.scl @var{class}}
4193 * Section:: @code{.section @var{name}[, @var{flags}]}
4196 * Set:: @code{.set @var{symbol}, @var{expression}}
4197 * Short:: @code{.short @var{expressions}}
4198 * Single:: @code{.single @var{flonums}}
4200 * Size:: @code{.size [@var{name} , @var{expression}]}
4202 @ifclear no-space-dir
4203 * Skip:: @code{.skip @var{size} , @var{fill}}
4206 * Sleb128:: @code{.sleb128 @var{expressions}}
4207 @ifclear no-space-dir
4208 * Space:: @code{.space @var{size} , @var{fill}}
4211 * Stab:: @code{.stabd, .stabn, .stabs}
4214 * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
4215 * Struct:: @code{.struct @var{expression}}
4217 * SubSection:: @code{.subsection}
4218 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
4222 * Tag:: @code{.tag @var{structname}}
4225 * Text:: @code{.text @var{subsection}}
4226 * Title:: @code{.title "@var{heading}"}
4228 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
4231 * Uleb128:: @code{.uleb128 @var{expressions}}
4233 * Val:: @code{.val @var{addr}}
4237 * Version:: @code{.version "@var{string}"}
4238 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
4239 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
4242 * Warning:: @code{.warning @var{string}}
4243 * Weak:: @code{.weak @var{names}}
4244 * Weakref:: @code{.weakref @var{alias}, @var{symbol}}
4245 * Word:: @code{.word @var{expressions}}
4246 * Deprecated:: Deprecated Directives
4250 @section @code{.abort}
4252 @cindex @code{abort} directive
4253 @cindex stopping the assembly
4254 This directive stops the assembly immediately. It is for
4255 compatibility with other assemblers. The original idea was that the
4256 assembly language source would be piped into the assembler. If the sender
4257 of the source quit, it could use this directive tells @command{@value{AS}} to
4258 quit also. One day @code{.abort} will not be supported.
4262 @section @code{.ABORT} (COFF)
4264 @cindex @code{ABORT} directive
4265 When producing COFF output, @command{@value{AS}} accepts this directive as a
4266 synonym for @samp{.abort}.
4269 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
4275 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4277 @cindex padding the location counter
4278 @cindex @code{align} directive
4279 Pad the location counter (in the current subsection) to a particular storage
4280 boundary. The first expression (which must be absolute) is the alignment
4281 required, as described below.
4283 The second expression (also absolute) gives the fill value to be stored in the
4284 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4285 padding bytes are normally zero. However, on some systems, if the section is
4286 marked as containing code and the fill value is omitted, the space is filled
4287 with no-op instructions.
4289 The third expression is also absolute, and is also optional. If it is present,
4290 it is the maximum number of bytes that should be skipped by this alignment
4291 directive. If doing the alignment would require skipping more bytes than the
4292 specified maximum, then the alignment is not done at all. You can omit the
4293 fill value (the second argument) entirely by simply using two commas after the
4294 required alignment; this can be useful if you want the alignment to be filled
4295 with no-op instructions when appropriate.
4297 The way the required alignment is specified varies from system to system.
4298 For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32,
4299 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
4300 alignment request in bytes. For example @samp{.align 8} advances
4301 the location counter until it is a multiple of 8. If the location counter
4302 is already a multiple of 8, no change is needed. For the tic54x, the
4303 first expression is the alignment request in words.
4305 For other systems, including ppc, i386 using a.out format, arm and
4306 strongarm, it is the
4307 number of low-order zero bits the location counter must have after
4308 advancement. For example @samp{.align 3} advances the location
4309 counter until it a multiple of 8. If the location counter is already a
4310 multiple of 8, no change is needed.
4312 This inconsistency is due to the different behaviors of the various
4313 native assemblers for these systems which GAS must emulate.
4314 GAS also provides @code{.balign} and @code{.p2align} directives,
4315 described later, which have a consistent behavior across all
4316 architectures (but are specific to GAS).
4319 @section @code{.altmacro}
4320 Enable alternate macro mode, enabling:
4323 @item LOCAL @var{name} [ , @dots{} ]
4324 One additional directive, @code{LOCAL}, is available. It is used to
4325 generate a string replacement for each of the @var{name} arguments, and
4326 replace any instances of @var{name} in each macro expansion. The
4327 replacement string is unique in the assembly, and different for each
4328 separate macro expansion. @code{LOCAL} allows you to write macros that
4329 define symbols, without fear of conflict between separate macro expansions.
4331 @item String delimiters
4332 You can write strings delimited in these other ways besides
4333 @code{"@var{string}"}:
4336 @item '@var{string}'
4337 You can delimit strings with single-quote characters.
4339 @item <@var{string}>
4340 You can delimit strings with matching angle brackets.
4343 @item single-character string escape
4344 To include any single character literally in a string (even if the
4345 character would otherwise have some special meaning), you can prefix the
4346 character with @samp{!} (an exclamation mark). For example, you can
4347 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4349 @item Expression results as strings
4350 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4351 and use the result as a string.
4355 @section @code{.ascii "@var{string}"}@dots{}
4357 @cindex @code{ascii} directive
4358 @cindex string literals
4359 @code{.ascii} expects zero or more string literals (@pxref{Strings})
4360 separated by commas. It assembles each string (with no automatic
4361 trailing zero byte) into consecutive addresses.
4364 @section @code{.asciz "@var{string}"}@dots{}
4366 @cindex @code{asciz} directive
4367 @cindex zero-terminated strings
4368 @cindex null-terminated strings
4369 @code{.asciz} is just like @code{.ascii}, but each string is followed by
4370 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
4373 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4375 @cindex padding the location counter given number of bytes
4376 @cindex @code{balign} directive
4377 Pad the location counter (in the current subsection) to a particular
4378 storage boundary. The first expression (which must be absolute) is the
4379 alignment request in bytes. For example @samp{.balign 8} advances
4380 the location counter until it is a multiple of 8. If the location counter
4381 is already a multiple of 8, no change is needed.
4383 The second expression (also absolute) gives the fill value to be stored in the
4384 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4385 padding bytes are normally zero. However, on some systems, if the section is
4386 marked as containing code and the fill value is omitted, the space is filled
4387 with no-op instructions.
4389 The third expression is also absolute, and is also optional. If it is present,
4390 it is the maximum number of bytes that should be skipped by this alignment
4391 directive. If doing the alignment would require skipping more bytes than the
4392 specified maximum, then the alignment is not done at all. You can omit the
4393 fill value (the second argument) entirely by simply using two commas after the
4394 required alignment; this can be useful if you want the alignment to be filled
4395 with no-op instructions when appropriate.
4397 @cindex @code{balignw} directive
4398 @cindex @code{balignl} directive
4399 The @code{.balignw} and @code{.balignl} directives are variants of the
4400 @code{.balign} directive. The @code{.balignw} directive treats the fill
4401 pattern as a two byte word value. The @code{.balignl} directives treats the
4402 fill pattern as a four byte longword value. For example, @code{.balignw
4403 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4404 filled in with the value 0x368d (the exact placement of the bytes depends upon
4405 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4408 @node Bundle directives
4409 @section @code{.bundle_align_mode @var{abs-expr}}
4410 @cindex @code{bundle_align_mode} directive
4412 @cindex instruction bundle
4413 @cindex aligned instruction bundle
4414 @code{.bundle_align_mode} enables or disables @dfn{aligned instruction
4415 bundle} mode. In this mode, sequences of adjacent instructions are grouped
4416 into fixed-sized @dfn{bundles}. If the argument is zero, this mode is
4417 disabled (which is the default state). If the argument it not zero, it
4418 gives the size of an instruction bundle as a power of two (as for the
4419 @code{.p2align} directive, @pxref{P2align}).
4421 For some targets, it's an ABI requirement that no instruction may span a
4422 certain aligned boundary. A @dfn{bundle} is simply a sequence of
4423 instructions that starts on an aligned boundary. For example, if
4424 @var{abs-expr} is @code{5} then the bundle size is 32, so each aligned
4425 chunk of 32 bytes is a bundle. When aligned instruction bundle mode is in
4426 effect, no single instruction may span a boundary between bundles. If an
4427 instruction would start too close to the end of a bundle for the length of
4428 that particular instruction to fit within the bundle, then the space at the
4429 end of that bundle is filled with no-op instructions so the instruction
4430 starts in the next bundle. As a corollary, it's an error if any single
4431 instruction's encoding is longer than the bundle size.
4433 @section @code{.bundle_lock} and @code{.bundle_unlock}
4434 @cindex @code{bundle_lock} directive
4435 @cindex @code{bundle_unlock} directive
4436 The @code{.bundle_lock} and directive @code{.bundle_unlock} directives
4437 allow explicit control over instruction bundle padding. These directives
4438 are only valid when @code{.bundle_align_mode} has been used to enable
4439 aligned instruction bundle mode. It's an error if they appear when
4440 @code{.bundle_align_mode} has not been used at all, or when the last
4441 directive was @w{@code{.bundle_align_mode 0}}.
4443 @cindex bundle-locked
4444 For some targets, it's an ABI requirement that certain instructions may
4445 appear only as part of specified permissible sequences of multiple
4446 instructions, all within the same bundle. A pair of @code{.bundle_lock}
4447 and @code{.bundle_unlock} directives define a @dfn{bundle-locked}
4448 instruction sequence. For purposes of aligned instruction bundle mode, a
4449 sequence starting with @code{.bundle_lock} and ending with
4450 @code{.bundle_unlock} is treated as a single instruction. That is, the
4451 entire sequence must fit into a single bundle and may not span a bundle
4452 boundary. If necessary, no-op instructions will be inserted before the
4453 first instruction of the sequence so that the whole sequence starts on an
4454 aligned bundle boundary. It's an error if the sequence is longer than the
4457 For convenience when using @code{.bundle_lock} and @code{.bundle_unlock}
4458 inside assembler macros (@pxref{Macro}), bundle-locked sequences may be
4459 nested. That is, a second @code{.bundle_lock} directive before the next
4460 @code{.bundle_unlock} directive has no effect except that it must be
4461 matched by another closing @code{.bundle_unlock} so that there is the
4462 same number of @code{.bundle_lock} and @code{.bundle_unlock} directives.
4465 @section @code{.byte @var{expressions}}
4467 @cindex @code{byte} directive
4468 @cindex integers, one byte
4469 @code{.byte} expects zero or more expressions, separated by commas.
4470 Each expression is assembled into the next byte.
4472 @node CFI directives
4473 @section @code{.cfi_sections @var{section_list}}
4474 @cindex @code{cfi_sections} directive
4475 @code{.cfi_sections} may be used to specify whether CFI directives
4476 should emit @code{.eh_frame} section and/or @code{.debug_frame} section.
4477 If @var{section_list} is @code{.eh_frame}, @code{.eh_frame} is emitted,
4478 if @var{section_list} is @code{.debug_frame}, @code{.debug_frame} is emitted.
4479 To emit both use @code{.eh_frame, .debug_frame}. The default if this
4480 directive is not used is @code{.cfi_sections .eh_frame}.
4482 @section @code{.cfi_startproc [simple]}
4483 @cindex @code{cfi_startproc} directive
4484 @code{.cfi_startproc} is used at the beginning of each function that
4485 should have an entry in @code{.eh_frame}. It initializes some internal
4486 data structures. Don't forget to close the function by
4487 @code{.cfi_endproc}.
4489 Unless @code{.cfi_startproc} is used along with parameter @code{simple}
4490 it also emits some architecture dependent initial CFI instructions.
4492 @section @code{.cfi_endproc}
4493 @cindex @code{cfi_endproc} directive
4494 @code{.cfi_endproc} is used at the end of a function where it closes its
4495 unwind entry previously opened by
4496 @code{.cfi_startproc}, and emits it to @code{.eh_frame}.
4498 @section @code{.cfi_personality @var{encoding} [, @var{exp}]}
4499 @code{.cfi_personality} defines personality routine and its encoding.
4500 @var{encoding} must be a constant determining how the personality
4501 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4502 argument is not present, otherwise second argument should be
4503 a constant or a symbol name. When using indirect encodings,
4504 the symbol provided should be the location where personality
4505 can be loaded from, not the personality routine itself.
4506 The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff},
4507 no personality routine.
4509 @section @code{.cfi_lsda @var{encoding} [, @var{exp}]}
4510 @code{.cfi_lsda} defines LSDA and its encoding.
4511 @var{encoding} must be a constant determining how the LSDA
4512 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4513 argument is not present, otherwise second argument should be a constant
4514 or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff},
4517 @section @code{.cfi_def_cfa @var{register}, @var{offset}}
4518 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4519 address from @var{register} and add @var{offset} to it}.
4521 @section @code{.cfi_def_cfa_register @var{register}}
4522 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4523 now on @var{register} will be used instead of the old one. Offset
4526 @section @code{.cfi_def_cfa_offset @var{offset}}
4527 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4528 remains the same, but @var{offset} is new. Note that it is the
4529 absolute offset that will be added to a defined register to compute
4532 @section @code{.cfi_adjust_cfa_offset @var{offset}}
4533 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4534 value that is added/substracted from the previous offset.
4536 @section @code{.cfi_offset @var{register}, @var{offset}}
4537 Previous value of @var{register} is saved at offset @var{offset} from
4540 @section @code{.cfi_rel_offset @var{register}, @var{offset}}
4541 Previous value of @var{register} is saved at offset @var{offset} from
4542 the current CFA register. This is transformed to @code{.cfi_offset}
4543 using the known displacement of the CFA register from the CFA.
4544 This is often easier to use, because the number will match the
4545 code it's annotating.
4547 @section @code{.cfi_register @var{register1}, @var{register2}}
4548 Previous value of @var{register1} is saved in register @var{register2}.
4550 @section @code{.cfi_restore @var{register}}
4551 @code{.cfi_restore} says that the rule for @var{register} is now the
4552 same as it was at the beginning of the function, after all initial
4553 instruction added by @code{.cfi_startproc} were executed.
4555 @section @code{.cfi_undefined @var{register}}
4556 From now on the previous value of @var{register} can't be restored anymore.
4558 @section @code{.cfi_same_value @var{register}}
4559 Current value of @var{register} is the same like in the previous frame,
4560 i.e. no restoration needed.
4562 @section @code{.cfi_remember_state},
4563 First save all current rules for all registers by @code{.cfi_remember_state},
4564 then totally screw them up by subsequent @code{.cfi_*} directives and when
4565 everything is hopelessly bad, use @code{.cfi_restore_state} to restore
4566 the previous saved state.
4568 @section @code{.cfi_return_column @var{register}}
4569 Change return column @var{register}, i.e. the return address is either
4570 directly in @var{register} or can be accessed by rules for @var{register}.
4572 @section @code{.cfi_signal_frame}
4573 Mark current function as signal trampoline.
4575 @section @code{.cfi_window_save}
4576 SPARC register window has been saved.
4578 @section @code{.cfi_escape} @var{expression}[, @dots{}]
4579 Allows the user to add arbitrary bytes to the unwind info. One
4580 might use this to add OS-specific CFI opcodes, or generic CFI
4581 opcodes that GAS does not yet support.
4583 @section @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}}
4584 The current value of @var{register} is @var{label}. The value of @var{label}
4585 will be encoded in the output file according to @var{encoding}; see the
4586 description of @code{.cfi_personality} for details on this encoding.
4588 The usefulness of equating a register to a fixed label is probably
4589 limited to the return address register. Here, it can be useful to
4590 mark a code segment that has only one return address which is reached
4591 by a direct branch and no copy of the return address exists in memory
4592 or another register.
4595 @section @code{.comm @var{symbol} , @var{length} }
4597 @cindex @code{comm} directive
4598 @cindex symbol, common
4599 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
4600 common symbol in one object file may be merged with a defined or common symbol
4601 of the same name in another object file. If @code{@value{LD}} does not see a
4602 definition for the symbol--just one or more common symbols--then it will
4603 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
4604 absolute expression. If @code{@value{LD}} sees multiple common symbols with
4605 the same name, and they do not all have the same size, it will allocate space
4606 using the largest size.
4609 When using ELF or (as a GNU extension) PE, the @code{.comm} directive takes
4610 an optional third argument. This is the desired alignment of the symbol,
4611 specified for ELF as a byte boundary (for example, an alignment of 16 means
4612 that the least significant 4 bits of the address should be zero), and for PE
4613 as a power of two (for example, an alignment of 5 means aligned to a 32-byte
4614 boundary). The alignment must be an absolute expression, and it must be a
4615 power of two. If @code{@value{LD}} allocates uninitialized memory for the
4616 common symbol, it will use the alignment when placing the symbol. If no
4617 alignment is specified, @command{@value{AS}} will set the alignment to the
4618 largest power of two less than or equal to the size of the symbol, up to a
4619 maximum of 16 on ELF, or the default section alignment of 4 on PE@footnote{This
4620 is not the same as the executable image file alignment controlled by @code{@value{LD}}'s
4621 @samp{--section-alignment} option; image file sections in PE are aligned to
4622 multiples of 4096, which is far too large an alignment for ordinary variables.
4623 It is rather the default alignment for (non-debug) sections within object
4624 (@samp{*.o}) files, which are less strictly aligned.}.
4628 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4629 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4633 @section @code{.data @var{subsection}}
4635 @cindex @code{data} directive
4636 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4637 end of the data subsection numbered @var{subsection} (which is an
4638 absolute expression). If @var{subsection} is omitted, it defaults
4643 @section @code{.def @var{name}}
4645 @cindex @code{def} directive
4646 @cindex COFF symbols, debugging
4647 @cindex debugging COFF symbols
4648 Begin defining debugging information for a symbol @var{name}; the
4649 definition extends until the @code{.endef} directive is encountered.
4652 This directive is only observed when @command{@value{AS}} is configured for COFF
4653 format output; when producing @code{b.out}, @samp{.def} is recognized,
4660 @section @code{.desc @var{symbol}, @var{abs-expression}}
4662 @cindex @code{desc} directive
4663 @cindex COFF symbol descriptor
4664 @cindex symbol descriptor, COFF
4665 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4666 to the low 16 bits of an absolute expression.
4669 The @samp{.desc} directive is not available when @command{@value{AS}} is
4670 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4671 object format. For the sake of compatibility, @command{@value{AS}} accepts
4672 it, but produces no output, when configured for COFF.
4678 @section @code{.dim}
4680 @cindex @code{dim} directive
4681 @cindex COFF auxiliary symbol information
4682 @cindex auxiliary symbol information, COFF
4683 This directive is generated by compilers to include auxiliary debugging
4684 information in the symbol table. It is only permitted inside
4685 @code{.def}/@code{.endef} pairs.
4688 @samp{.dim} is only meaningful when generating COFF format output; when
4689 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4695 @section @code{.double @var{flonums}}
4697 @cindex @code{double} directive
4698 @cindex floating point numbers (double)
4699 @code{.double} expects zero or more flonums, separated by commas. It
4700 assembles floating point numbers.
4702 The exact kind of floating point numbers emitted depends on how
4703 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4707 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4708 in @sc{ieee} format.
4713 @section @code{.eject}
4715 @cindex @code{eject} directive
4716 @cindex new page, in listings
4717 @cindex page, in listings
4718 @cindex listing control: new page
4719 Force a page break at this point, when generating assembly listings.
4722 @section @code{.else}
4724 @cindex @code{else} directive
4725 @code{.else} is part of the @command{@value{AS}} support for conditional
4726 assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section
4727 of code to be assembled if the condition for the preceding @code{.if}
4731 @section @code{.elseif}
4733 @cindex @code{elseif} directive
4734 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4735 assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new
4736 @code{.if} block that would otherwise fill the entire @code{.else} section.
4739 @section @code{.end}
4741 @cindex @code{end} directive
4742 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4743 process anything in the file past the @code{.end} directive.
4747 @section @code{.endef}
4749 @cindex @code{endef} directive
4750 This directive flags the end of a symbol definition begun with
4754 @samp{.endef} is only meaningful when generating COFF format output; if
4755 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4756 directive but ignores it.
4761 @section @code{.endfunc}
4762 @cindex @code{endfunc} directive
4763 @code{.endfunc} marks the end of a function specified with @code{.func}.
4766 @section @code{.endif}
4768 @cindex @code{endif} directive
4769 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4770 it marks the end of a block of code that is only assembled
4771 conditionally. @xref{If,,@code{.if}}.
4774 @section @code{.equ @var{symbol}, @var{expression}}
4776 @cindex @code{equ} directive
4777 @cindex assigning values to symbols
4778 @cindex symbols, assigning values to
4779 This directive sets the value of @var{symbol} to @var{expression}.
4780 It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}.
4783 The syntax for @code{equ} on the HPPA is
4784 @samp{@var{symbol} .equ @var{expression}}.
4788 The syntax for @code{equ} on the Z80 is
4789 @samp{@var{symbol} equ @var{expression}}.
4790 On the Z80 it is an eror if @var{symbol} is already defined,
4791 but the symbol is not protected from later redefinition.
4792 Compare @ref{Equiv}.
4796 @section @code{.equiv @var{symbol}, @var{expression}}
4797 @cindex @code{equiv} directive
4798 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4799 the assembler will signal an error if @var{symbol} is already defined. Note a
4800 symbol which has been referenced but not actually defined is considered to be
4803 Except for the contents of the error message, this is roughly equivalent to
4810 plus it protects the symbol from later redefinition.
4813 @section @code{.eqv @var{symbol}, @var{expression}}
4814 @cindex @code{eqv} directive
4815 The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to
4816 evaluate the expression or any part of it immediately. Instead each time
4817 the resulting symbol is used in an expression, a snapshot of its current
4821 @section @code{.err}
4822 @cindex @code{err} directive
4823 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4824 message and, unless the @option{-Z} option was used, it will not generate an
4825 object file. This can be used to signal an error in conditionally compiled code.
4828 @section @code{.error "@var{string}"}
4829 @cindex error directive
4831 Similarly to @code{.err}, this directive emits an error, but you can specify a
4832 string that will be emitted as the error message. If you don't specify the
4833 message, it defaults to @code{".error directive invoked in source file"}.
4834 @xref{Errors, ,Error and Warning Messages}.
4837 .error "This code has not been assembled and tested."
4841 @section @code{.exitm}
4842 Exit early from the current macro definition. @xref{Macro}.
4845 @section @code{.extern}
4847 @cindex @code{extern} directive
4848 @code{.extern} is accepted in the source program---for compatibility
4849 with other assemblers---but it is ignored. @command{@value{AS}} treats
4850 all undefined symbols as external.
4853 @section @code{.fail @var{expression}}
4855 @cindex @code{fail} directive
4856 Generates an error or a warning. If the value of the @var{expression} is 500
4857 or more, @command{@value{AS}} will print a warning message. If the value is less
4858 than 500, @command{@value{AS}} will print an error message. The message will
4859 include the value of @var{expression}. This can occasionally be useful inside
4860 complex nested macros or conditional assembly.
4863 @section @code{.file}
4864 @cindex @code{file} directive
4866 @ifclear no-file-dir
4867 There are two different versions of the @code{.file} directive. Targets
4868 that support DWARF2 line number information use the DWARF2 version of
4869 @code{.file}. Other targets use the default version.
4871 @subheading Default Version
4873 @cindex logical file name
4874 @cindex file name, logical
4875 This version of the @code{.file} directive tells @command{@value{AS}} that we
4876 are about to start a new logical file. The syntax is:
4882 @var{string} is the new file name. In general, the filename is
4883 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4884 to specify an empty file name, you must give the quotes--@code{""}. This
4885 statement may go away in future: it is only recognized to be compatible with
4886 old @command{@value{AS}} programs.
4888 @subheading DWARF2 Version
4891 When emitting DWARF2 line number information, @code{.file} assigns filenames
4892 to the @code{.debug_line} file name table. The syntax is:
4895 .file @var{fileno} @var{filename}
4898 The @var{fileno} operand should be a unique positive integer to use as the
4899 index of the entry in the table. The @var{filename} operand is a C string
4902 The detail of filename indices is exposed to the user because the filename
4903 table is shared with the @code{.debug_info} section of the DWARF2 debugging
4904 information, and thus the user must know the exact indices that table
4908 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4910 @cindex @code{fill} directive
4911 @cindex writing patterns in memory
4912 @cindex patterns, writing in memory
4913 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4914 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4915 may be zero or more. @var{Size} may be zero or more, but if it is
4916 more than 8, then it is deemed to have the value 8, compatible with
4917 other people's assemblers. The contents of each @var{repeat} bytes
4918 is taken from an 8-byte number. The highest order 4 bytes are
4919 zero. The lowest order 4 bytes are @var{value} rendered in the
4920 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4921 Each @var{size} bytes in a repetition is taken from the lowest order
4922 @var{size} bytes of this number. Again, this bizarre behavior is
4923 compatible with other people's assemblers.
4925 @var{size} and @var{value} are optional.
4926 If the second comma and @var{value} are absent, @var{value} is
4927 assumed zero. If the first comma and following tokens are absent,
4928 @var{size} is assumed to be 1.
4931 @section @code{.float @var{flonums}}
4933 @cindex floating point numbers (single)
4934 @cindex @code{float} directive
4935 This directive assembles zero or more flonums, separated by commas. It
4936 has the same effect as @code{.single}.
4938 The exact kind of floating point numbers emitted depends on how
4939 @command{@value{AS}} is configured.
4940 @xref{Machine Dependencies}.
4944 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4945 in @sc{ieee} format.
4950 @section @code{.func @var{name}[,@var{label}]}
4951 @cindex @code{func} directive
4952 @code{.func} emits debugging information to denote function @var{name}, and
4953 is ignored unless the file is assembled with debugging enabled.
4954 Only @samp{--gstabs[+]} is currently supported.
4955 @var{label} is the entry point of the function and if omitted @var{name}
4956 prepended with the @samp{leading char} is used.
4957 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4958 All functions are currently defined to have @code{void} return type.
4959 The function must be terminated with @code{.endfunc}.
4962 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4964 @cindex @code{global} directive
4965 @cindex symbol, making visible to linker
4966 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4967 @var{symbol} in your partial program, its value is made available to
4968 other partial programs that are linked with it. Otherwise,
4969 @var{symbol} takes its attributes from a symbol of the same name
4970 from another file linked into the same program.
4972 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4973 compatibility with other assemblers.
4976 On the HPPA, @code{.global} is not always enough to make it accessible to other
4977 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4978 @xref{HPPA Directives, ,HPPA Assembler Directives}.
4983 @section @code{.gnu_attribute @var{tag},@var{value}}
4984 Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
4987 @section @code{.hidden @var{names}}
4989 @cindex @code{hidden} directive
4991 This is one of the ELF visibility directives. The other two are
4992 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4993 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4995 This directive overrides the named symbols default visibility (which is set by
4996 their binding: local, global or weak). The directive sets the visibility to
4997 @code{hidden} which means that the symbols are not visible to other components.
4998 Such symbols are always considered to be @code{protected} as well.
5002 @section @code{.hword @var{expressions}}
5004 @cindex @code{hword} directive
5005 @cindex integers, 16-bit
5006 @cindex numbers, 16-bit
5007 @cindex sixteen bit integers
5008 This expects zero or more @var{expressions}, and emits
5009 a 16 bit number for each.
5012 This directive is a synonym for @samp{.short}; depending on the target
5013 architecture, it may also be a synonym for @samp{.word}.
5017 This directive is a synonym for @samp{.short}.
5020 This directive is a synonym for both @samp{.short} and @samp{.word}.
5025 @section @code{.ident}
5027 @cindex @code{ident} directive
5029 This directive is used by some assemblers to place tags in object files. The
5030 behavior of this directive varies depending on the target. When using the
5031 a.out object file format, @command{@value{AS}} simply accepts the directive for
5032 source-file compatibility with existing assemblers, but does not emit anything
5033 for it. When using COFF, comments are emitted to the @code{.comment} or
5034 @code{.rdata} section, depending on the target. When using ELF, comments are
5035 emitted to the @code{.comment} section.
5038 @section @code{.if @var{absolute expression}}
5040 @cindex conditional assembly
5041 @cindex @code{if} directive
5042 @code{.if} marks the beginning of a section of code which is only
5043 considered part of the source program being assembled if the argument
5044 (which must be an @var{absolute expression}) is non-zero. The end of
5045 the conditional section of code must be marked by @code{.endif}
5046 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
5047 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
5048 If you have several conditions to check, @code{.elseif} may be used to avoid
5049 nesting blocks if/else within each subsequent @code{.else} block.
5051 The following variants of @code{.if} are also supported:
5053 @cindex @code{ifdef} directive
5054 @item .ifdef @var{symbol}
5055 Assembles the following section of code if the specified @var{symbol}
5056 has been defined. Note a symbol which has been referenced but not yet defined
5057 is considered to be undefined.
5059 @cindex @code{ifb} directive
5060 @item .ifb @var{text}
5061 Assembles the following section of code if the operand is blank (empty).
5063 @cindex @code{ifc} directive
5064 @item .ifc @var{string1},@var{string2}
5065 Assembles the following section of code if the two strings are the same. The
5066 strings may be optionally quoted with single quotes. If they are not quoted,
5067 the first string stops at the first comma, and the second string stops at the
5068 end of the line. Strings which contain whitespace should be quoted. The
5069 string comparison is case sensitive.
5071 @cindex @code{ifeq} directive
5072 @item .ifeq @var{absolute expression}
5073 Assembles the following section of code if the argument is zero.
5075 @cindex @code{ifeqs} directive
5076 @item .ifeqs @var{string1},@var{string2}
5077 Another form of @code{.ifc}. The strings must be quoted using double quotes.
5079 @cindex @code{ifge} directive
5080 @item .ifge @var{absolute expression}
5081 Assembles the following section of code if the argument is greater than or
5084 @cindex @code{ifgt} directive
5085 @item .ifgt @var{absolute expression}
5086 Assembles the following section of code if the argument is greater than zero.
5088 @cindex @code{ifle} directive
5089 @item .ifle @var{absolute expression}
5090 Assembles the following section of code if the argument is less than or equal
5093 @cindex @code{iflt} directive
5094 @item .iflt @var{absolute expression}
5095 Assembles the following section of code if the argument is less than zero.
5097 @cindex @code{ifnb} directive
5098 @item .ifnb @var{text}
5099 Like @code{.ifb}, but the sense of the test is reversed: this assembles the
5100 following section of code if the operand is non-blank (non-empty).
5102 @cindex @code{ifnc} directive
5103 @item .ifnc @var{string1},@var{string2}.
5104 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
5105 following section of code if the two strings are not the same.
5107 @cindex @code{ifndef} directive
5108 @cindex @code{ifnotdef} directive
5109 @item .ifndef @var{symbol}
5110 @itemx .ifnotdef @var{symbol}
5111 Assembles the following section of code if the specified @var{symbol}
5112 has not been defined. Both spelling variants are equivalent. Note a symbol
5113 which has been referenced but not yet defined is considered to be undefined.
5115 @cindex @code{ifne} directive
5116 @item .ifne @var{absolute expression}
5117 Assembles the following section of code if the argument is not equal to zero
5118 (in other words, this is equivalent to @code{.if}).
5120 @cindex @code{ifnes} directive
5121 @item .ifnes @var{string1},@var{string2}
5122 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
5123 following section of code if the two strings are not the same.
5127 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
5129 @cindex @code{incbin} directive
5130 @cindex binary files, including
5131 The @code{incbin} directive includes @var{file} verbatim at the current
5132 location. You can control the search paths used with the @samp{-I} command-line
5133 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5136 The @var{skip} argument skips a number of bytes from the start of the
5137 @var{file}. The @var{count} argument indicates the maximum number of bytes to
5138 read. Note that the data is not aligned in any way, so it is the user's
5139 responsibility to make sure that proper alignment is provided both before and
5140 after the @code{incbin} directive.
5143 @section @code{.include "@var{file}"}
5145 @cindex @code{include} directive
5146 @cindex supporting files, including
5147 @cindex files, including
5148 This directive provides a way to include supporting files at specified
5149 points in your source program. The code from @var{file} is assembled as
5150 if it followed the point of the @code{.include}; when the end of the
5151 included file is reached, assembly of the original file continues. You
5152 can control the search paths used with the @samp{-I} command-line option
5153 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
5157 @section @code{.int @var{expressions}}
5159 @cindex @code{int} directive
5160 @cindex integers, 32-bit
5161 Expect zero or more @var{expressions}, of any section, separated by commas.
5162 For each expression, emit a number that, at run time, is the value of that
5163 expression. The byte order and bit size of the number depends on what kind
5164 of target the assembly is for.
5168 On most forms of the H8/300, @code{.int} emits 16-bit
5169 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
5176 @section @code{.internal @var{names}}
5178 @cindex @code{internal} directive
5180 This is one of the ELF visibility directives. The other two are
5181 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
5182 @code{.protected} (@pxref{Protected,,@code{.protected}}).
5184 This directive overrides the named symbols default visibility (which is set by
5185 their binding: local, global or weak). The directive sets the visibility to
5186 @code{internal} which means that the symbols are considered to be @code{hidden}
5187 (i.e., not visible to other components), and that some extra, processor specific
5188 processing must also be performed upon the symbols as well.
5192 @section @code{.irp @var{symbol},@var{values}}@dots{}
5194 @cindex @code{irp} directive
5195 Evaluate a sequence of statements assigning different values to @var{symbol}.
5196 The sequence of statements starts at the @code{.irp} directive, and is
5197 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
5198 set to @var{value}, and the sequence of statements is assembled. If no
5199 @var{value} is listed, the sequence of statements is assembled once, with
5200 @var{symbol} set to the null string. To refer to @var{symbol} within the
5201 sequence of statements, use @var{\symbol}.
5203 For example, assembling
5211 is equivalent to assembling
5219 For some caveats with the spelling of @var{symbol}, see also @ref{Macro}.
5222 @section @code{.irpc @var{symbol},@var{values}}@dots{}
5224 @cindex @code{irpc} directive
5225 Evaluate a sequence of statements assigning different values to @var{symbol}.
5226 The sequence of statements starts at the @code{.irpc} directive, and is
5227 terminated by an @code{.endr} directive. For each character in @var{value},
5228 @var{symbol} is set to the character, and the sequence of statements is
5229 assembled. If no @var{value} is listed, the sequence of statements is
5230 assembled once, with @var{symbol} set to the null string. To refer to
5231 @var{symbol} within the sequence of statements, use @var{\symbol}.
5233 For example, assembling
5241 is equivalent to assembling
5249 For some caveats with the spelling of @var{symbol}, see also the discussion
5253 @section @code{.lcomm @var{symbol} , @var{length}}
5255 @cindex @code{lcomm} directive
5256 @cindex local common symbols
5257 @cindex symbols, local common
5258 Reserve @var{length} (an absolute expression) bytes for a local common
5259 denoted by @var{symbol}. The section and value of @var{symbol} are
5260 those of the new local common. The addresses are allocated in the bss
5261 section, so that at run-time the bytes start off zeroed. @var{Symbol}
5262 is not declared global (@pxref{Global,,@code{.global}}), so is normally
5263 not visible to @code{@value{LD}}.
5266 Some targets permit a third argument to be used with @code{.lcomm}. This
5267 argument specifies the desired alignment of the symbol in the bss section.
5271 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
5272 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
5276 @section @code{.lflags}
5278 @cindex @code{lflags} directive (ignored)
5279 @command{@value{AS}} accepts this directive, for compatibility with other
5280 assemblers, but ignores it.
5282 @ifclear no-line-dir
5284 @section @code{.line @var{line-number}}
5286 @cindex @code{line} directive
5287 @cindex logical line number
5289 Change the logical line number. @var{line-number} must be an absolute
5290 expression. The next line has that logical line number. Therefore any other
5291 statements on the current line (after a statement separator character) are
5292 reported as on logical line number @var{line-number} @minus{} 1. One day
5293 @command{@value{AS}} will no longer support this directive: it is recognized only
5294 for compatibility with existing assembler programs.
5297 Even though this is a directive associated with the @code{a.out} or
5298 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
5299 when producing COFF output, and treats @samp{.line} as though it
5300 were the COFF @samp{.ln} @emph{if} it is found outside a
5301 @code{.def}/@code{.endef} pair.
5303 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
5304 used by compilers to generate auxiliary symbol information for
5309 @section @code{.linkonce [@var{type}]}
5311 @cindex @code{linkonce} directive
5312 @cindex common sections
5313 Mark the current section so that the linker only includes a single copy of it.
5314 This may be used to include the same section in several different object files,
5315 but ensure that the linker will only include it once in the final output file.
5316 The @code{.linkonce} pseudo-op must be used for each instance of the section.
5317 Duplicate sections are detected based on the section name, so it should be
5320 This directive is only supported by a few object file formats; as of this
5321 writing, the only object file format which supports it is the Portable
5322 Executable format used on Windows NT.
5324 The @var{type} argument is optional. If specified, it must be one of the
5325 following strings. For example:
5329 Not all types may be supported on all object file formats.
5333 Silently discard duplicate sections. This is the default.
5336 Warn if there are duplicate sections, but still keep only one copy.
5339 Warn if any of the duplicates have different sizes.
5342 Warn if any of the duplicates do not have exactly the same contents.
5346 @section @code{.list}
5348 @cindex @code{list} directive
5349 @cindex listing control, turning on
5350 Control (in conjunction with the @code{.nolist} directive) whether or
5351 not assembly listings are generated. These two directives maintain an
5352 internal counter (which is zero initially). @code{.list} increments the
5353 counter, and @code{.nolist} decrements it. Assembly listings are
5354 generated whenever the counter is greater than zero.
5356 By default, listings are disabled. When you enable them (with the
5357 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
5358 the initial value of the listing counter is one.
5361 @section @code{.ln @var{line-number}}
5363 @cindex @code{ln} directive
5364 @ifclear no-line-dir
5365 @samp{.ln} is a synonym for @samp{.line}.
5368 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
5369 must be an absolute expression. The next line has that logical
5370 line number, so any other statements on the current line (after a
5371 statement separator character @code{;}) are reported as on logical
5372 line number @var{line-number} @minus{} 1.
5375 This directive is accepted, but ignored, when @command{@value{AS}} is
5376 configured for @code{b.out}; its effect is only associated with COFF
5382 @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]}
5383 @cindex @code{loc} directive
5384 When emitting DWARF2 line number information,
5385 the @code{.loc} directive will add a row to the @code{.debug_line} line
5386 number matrix corresponding to the immediately following assembly
5387 instruction. The @var{fileno}, @var{lineno}, and optional @var{column}
5388 arguments will be applied to the @code{.debug_line} state machine before
5391 The @var{options} are a sequence of the following tokens in any order:
5395 This option will set the @code{basic_block} register in the
5396 @code{.debug_line} state machine to @code{true}.
5399 This option will set the @code{prologue_end} register in the
5400 @code{.debug_line} state machine to @code{true}.
5402 @item epilogue_begin
5403 This option will set the @code{epilogue_begin} register in the
5404 @code{.debug_line} state machine to @code{true}.
5406 @item is_stmt @var{value}
5407 This option will set the @code{is_stmt} register in the
5408 @code{.debug_line} state machine to @code{value}, which must be
5411 @item isa @var{value}
5412 This directive will set the @code{isa} register in the @code{.debug_line}
5413 state machine to @var{value}, which must be an unsigned integer.
5415 @item discriminator @var{value}
5416 This directive will set the @code{discriminator} register in the @code{.debug_line}
5417 state machine to @var{value}, which must be an unsigned integer.
5421 @node Loc_mark_labels
5422 @section @code{.loc_mark_labels @var{enable}}
5423 @cindex @code{loc_mark_labels} directive
5424 When emitting DWARF2 line number information,
5425 the @code{.loc_mark_labels} directive makes the assembler emit an entry
5426 to the @code{.debug_line} line number matrix with the @code{basic_block}
5427 register in the state machine set whenever a code label is seen.
5428 The @var{enable} argument should be either 1 or 0, to enable or disable
5429 this function respectively.
5433 @section @code{.local @var{names}}
5435 @cindex @code{local} directive
5436 This directive, which is available for ELF targets, marks each symbol in
5437 the comma-separated list of @code{names} as a local symbol so that it
5438 will not be externally visible. If the symbols do not already exist,
5439 they will be created.
5441 For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not
5442 accept an alignment argument, which is the case for most ELF targets,
5443 the @code{.local} directive can be used in combination with @code{.comm}
5444 (@pxref{Comm}) to define aligned local common data.
5448 @section @code{.long @var{expressions}}
5450 @cindex @code{long} directive
5451 @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}.
5454 @c no one seems to know what this is for or whether this description is
5455 @c what it really ought to do
5457 @section @code{.lsym @var{symbol}, @var{expression}}
5459 @cindex @code{lsym} directive
5460 @cindex symbol, not referenced in assembly
5461 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
5462 the hash table, ensuring it cannot be referenced by name during the
5463 rest of the assembly. This sets the attributes of the symbol to be
5464 the same as the expression value:
5466 @var{other} = @var{descriptor} = 0
5467 @var{type} = @r{(section of @var{expression})}
5468 @var{value} = @var{expression}
5471 The new symbol is not flagged as external.
5475 @section @code{.macro}
5478 The commands @code{.macro} and @code{.endm} allow you to define macros that
5479 generate assembly output. For example, this definition specifies a macro
5480 @code{sum} that puts a sequence of numbers into memory:
5483 .macro sum from=0, to=5
5492 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
5504 @item .macro @var{macname}
5505 @itemx .macro @var{macname} @var{macargs} @dots{}
5506 @cindex @code{macro} directive
5507 Begin the definition of a macro called @var{macname}. If your macro
5508 definition requires arguments, specify their names after the macro name,
5509 separated by commas or spaces. You can qualify the macro argument to
5510 indicate whether all invocations must specify a non-blank value (through
5511 @samp{:@code{req}}), or whether it takes all of the remaining arguments
5512 (through @samp{:@code{vararg}}). You can supply a default value for any
5513 macro argument by following the name with @samp{=@var{deflt}}. You
5514 cannot define two macros with the same @var{macname} unless it has been
5515 subject to the @code{.purgem} directive (@pxref{Purgem}) between the two
5516 definitions. For example, these are all valid @code{.macro} statements:
5520 Begin the definition of a macro called @code{comm}, which takes no
5523 @item .macro plus1 p, p1
5524 @itemx .macro plus1 p p1
5525 Either statement begins the definition of a macro called @code{plus1},
5526 which takes two arguments; within the macro definition, write
5527 @samp{\p} or @samp{\p1} to evaluate the arguments.
5529 @item .macro reserve_str p1=0 p2
5530 Begin the definition of a macro called @code{reserve_str}, with two
5531 arguments. The first argument has a default value, but not the second.
5532 After the definition is complete, you can call the macro either as
5533 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
5534 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
5535 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
5536 @samp{0}, and @samp{\p2} evaluating to @var{b}).
5538 @item .macro m p1:req, p2=0, p3:vararg
5539 Begin the definition of a macro called @code{m}, with at least three
5540 arguments. The first argument must always have a value specified, but
5541 not the second, which instead has a default value. The third formal
5542 will get assigned all remaining arguments specified at invocation time.
5544 When you call a macro, you can specify the argument values either by
5545 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
5546 @samp{sum to=17, from=9}.
5550 Note that since each of the @var{macargs} can be an identifier exactly
5551 as any other one permitted by the target architecture, there may be
5552 occasional problems if the target hand-crafts special meanings to certain
5553 characters when they occur in a special position. For example, if the colon
5554 (@code{:}) is generally permitted to be part of a symbol name, but the
5555 architecture specific code special-cases it when occurring as the final
5556 character of a symbol (to denote a label), then the macro parameter
5557 replacement code will have no way of knowing that and consider the whole
5558 construct (including the colon) an identifier, and check only this
5559 identifier for being the subject to parameter substitution. So for example
5560 this macro definition:
5568 might not work as expected. Invoking @samp{label foo} might not create a label
5569 called @samp{foo} but instead just insert the text @samp{\l:} into the
5570 assembler source, probably generating an error about an unrecognised
5573 Similarly problems might occur with the period character (@samp{.})
5574 which is often allowed inside opcode names (and hence identifier names). So
5575 for example constructing a macro to build an opcode from a base name and a
5576 length specifier like this:
5579 .macro opcode base length
5584 and invoking it as @samp{opcode store l} will not create a @samp{store.l}
5585 instruction but instead generate some kind of error as the assembler tries to
5586 interpret the text @samp{\base.\length}.
5588 There are several possible ways around this problem:
5591 @item Insert white space
5592 If it is possible to use white space characters then this is the simplest
5601 @item Use @samp{\()}
5602 The string @samp{\()} can be used to separate the end of a macro argument from
5603 the following text. eg:
5606 .macro opcode base length
5611 @item Use the alternate macro syntax mode
5612 In the alternative macro syntax mode the ampersand character (@samp{&}) can be
5613 used as a separator. eg:
5623 Note: this problem of correctly identifying string parameters to pseudo ops
5624 also applies to the identifiers used in @code{.irp} (@pxref{Irp})
5625 and @code{.irpc} (@pxref{Irpc}) as well.
5628 @cindex @code{endm} directive
5629 Mark the end of a macro definition.
5632 @cindex @code{exitm} directive
5633 Exit early from the current macro definition.
5635 @cindex number of macros executed
5636 @cindex macros, count executed
5638 @command{@value{AS}} maintains a counter of how many macros it has
5639 executed in this pseudo-variable; you can copy that number to your
5640 output with @samp{\@@}, but @emph{only within a macro definition}.
5642 @item LOCAL @var{name} [ , @dots{} ]
5643 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
5644 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
5645 @xref{Altmacro,,@code{.altmacro}}.
5649 @section @code{.mri @var{val}}
5651 @cindex @code{mri} directive
5652 @cindex MRI mode, temporarily
5653 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
5654 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
5655 affects code assembled until the next @code{.mri} directive, or until the end
5656 of the file. @xref{M, MRI mode, MRI mode}.
5659 @section @code{.noaltmacro}
5660 Disable alternate macro mode. @xref{Altmacro}.
5663 @section @code{.nolist}
5665 @cindex @code{nolist} directive
5666 @cindex listing control, turning off
5667 Control (in conjunction with the @code{.list} directive) whether or
5668 not assembly listings are generated. These two directives maintain an
5669 internal counter (which is zero initially). @code{.list} increments the
5670 counter, and @code{.nolist} decrements it. Assembly listings are
5671 generated whenever the counter is greater than zero.
5674 @section @code{.octa @var{bignums}}
5676 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
5677 @cindex @code{octa} directive
5678 @cindex integer, 16-byte
5679 @cindex sixteen byte integer
5680 This directive expects zero or more bignums, separated by commas. For each
5681 bignum, it emits a 16-byte integer.
5683 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
5684 hence @emph{octa}-word for 16 bytes.
5687 @section @code{.offset @var{loc}}
5689 @cindex @code{offset} directive
5690 Set the location counter to @var{loc} in the absolute section. @var{loc} must
5691 be an absolute expression. This directive may be useful for defining
5692 symbols with absolute values. Do not confuse it with the @code{.org}
5696 @section @code{.org @var{new-lc} , @var{fill}}
5698 @cindex @code{org} directive
5699 @cindex location counter, advancing
5700 @cindex advancing location counter
5701 @cindex current address, advancing
5702 Advance the location counter of the current section to
5703 @var{new-lc}. @var{new-lc} is either an absolute expression or an
5704 expression with the same section as the current subsection. That is,
5705 you can't use @code{.org} to cross sections: if @var{new-lc} has the
5706 wrong section, the @code{.org} directive is ignored. To be compatible
5707 with former assemblers, if the section of @var{new-lc} is absolute,
5708 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
5709 is the same as the current subsection.
5711 @code{.org} may only increase the location counter, or leave it
5712 unchanged; you cannot use @code{.org} to move the location counter
5715 @c double negative used below "not undefined" because this is a specific
5716 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
5717 @c section. doc@cygnus.com 18feb91
5718 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
5719 may not be undefined. If you really detest this restriction we eagerly await
5720 a chance to share your improved assembler.
5722 Beware that the origin is relative to the start of the section, not
5723 to the start of the subsection. This is compatible with other
5724 people's assemblers.
5726 When the location counter (of the current subsection) is advanced, the
5727 intervening bytes are filled with @var{fill} which should be an
5728 absolute expression. If the comma and @var{fill} are omitted,
5729 @var{fill} defaults to zero.
5732 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
5734 @cindex padding the location counter given a power of two
5735 @cindex @code{p2align} directive
5736 Pad the location counter (in the current subsection) to a particular
5737 storage boundary. The first expression (which must be absolute) is the
5738 number of low-order zero bits the location counter must have after
5739 advancement. For example @samp{.p2align 3} advances the location
5740 counter until it a multiple of 8. If the location counter is already a
5741 multiple of 8, no change is needed.
5743 The second expression (also absolute) gives the fill value to be stored in the
5744 padding bytes. It (and the comma) may be omitted. If it is omitted, the
5745 padding bytes are normally zero. However, on some systems, if the section is
5746 marked as containing code and the fill value is omitted, the space is filled
5747 with no-op instructions.
5749 The third expression is also absolute, and is also optional. If it is present,
5750 it is the maximum number of bytes that should be skipped by this alignment
5751 directive. If doing the alignment would require skipping more bytes than the
5752 specified maximum, then the alignment is not done at all. You can omit the
5753 fill value (the second argument) entirely by simply using two commas after the
5754 required alignment; this can be useful if you want the alignment to be filled
5755 with no-op instructions when appropriate.
5757 @cindex @code{p2alignw} directive
5758 @cindex @code{p2alignl} directive
5759 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5760 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5761 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5762 fill pattern as a four byte longword value. For example, @code{.p2alignw
5763 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5764 filled in with the value 0x368d (the exact placement of the bytes depends upon
5765 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5770 @section @code{.popsection}
5772 @cindex @code{popsection} directive
5773 @cindex Section Stack
5774 This is one of the ELF section stack manipulation directives. The others are
5775 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5776 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5779 This directive replaces the current section (and subsection) with the top
5780 section (and subsection) on the section stack. This section is popped off the
5786 @section @code{.previous}
5788 @cindex @code{previous} directive
5789 @cindex Section Stack
5790 This is one of the ELF section stack manipulation directives. The others are
5791 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5792 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5793 (@pxref{PopSection}).
5795 This directive swaps the current section (and subsection) with most recently
5796 referenced section/subsection pair prior to this one. Multiple
5797 @code{.previous} directives in a row will flip between two sections (and their
5798 subsections). For example:
5810 Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
5816 # Now in section A subsection 1
5820 # Now in section B subsection 0
5823 # Now in section B subsection 1
5826 # Now in section B subsection 0
5830 Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
5831 section B and 0x9abc into subsection 1 of section B.
5833 In terms of the section stack, this directive swaps the current section with
5834 the top section on the section stack.
5838 @section @code{.print @var{string}}
5840 @cindex @code{print} directive
5841 @command{@value{AS}} will print @var{string} on the standard output during
5842 assembly. You must put @var{string} in double quotes.
5846 @section @code{.protected @var{names}}
5848 @cindex @code{protected} directive
5850 This is one of the ELF visibility directives. The other two are
5851 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
5853 This directive overrides the named symbols default visibility (which is set by
5854 their binding: local, global or weak). The directive sets the visibility to
5855 @code{protected} which means that any references to the symbols from within the
5856 components that defines them must be resolved to the definition in that
5857 component, even if a definition in another component would normally preempt
5862 @section @code{.psize @var{lines} , @var{columns}}
5864 @cindex @code{psize} directive
5865 @cindex listing control: paper size
5866 @cindex paper size, for listings
5867 Use this directive to declare the number of lines---and, optionally, the
5868 number of columns---to use for each page, when generating listings.
5870 If you do not use @code{.psize}, listings use a default line-count
5871 of 60. You may omit the comma and @var{columns} specification; the
5872 default width is 200 columns.
5874 @command{@value{AS}} generates formfeeds whenever the specified number of
5875 lines is exceeded (or whenever you explicitly request one, using
5878 If you specify @var{lines} as @code{0}, no formfeeds are generated save
5879 those explicitly specified with @code{.eject}.
5882 @section @code{.purgem @var{name}}
5884 @cindex @code{purgem} directive
5885 Undefine the macro @var{name}, so that later uses of the string will not be
5886 expanded. @xref{Macro}.
5890 @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]}
5892 @cindex @code{pushsection} directive
5893 @cindex Section Stack
5894 This is one of the ELF section stack manipulation directives. The others are
5895 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5896 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5899 This directive pushes the current section (and subsection) onto the
5900 top of the section stack, and then replaces the current section and
5901 subsection with @code{name} and @code{subsection}. The optional
5902 @code{flags}, @code{type} and @code{arguments} are treated the same
5903 as in the @code{.section} (@pxref{Section}) directive.
5907 @section @code{.quad @var{bignums}}
5909 @cindex @code{quad} directive
5910 @code{.quad} expects zero or more bignums, separated by commas. For
5911 each bignum, it emits
5913 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
5914 warning message; and just takes the lowest order 8 bytes of the bignum.
5915 @cindex eight-byte integer
5916 @cindex integer, 8-byte
5918 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
5919 hence @emph{quad}-word for 8 bytes.
5922 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
5923 warning message; and just takes the lowest order 16 bytes of the bignum.
5924 @cindex sixteen-byte integer
5925 @cindex integer, 16-byte
5929 @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
5931 @cindex @code{reloc} directive
5932 Generate a relocation at @var{offset} of type @var{reloc_name} with value
5933 @var{expression}. If @var{offset} is a number, the relocation is generated in
5934 the current section. If @var{offset} is an expression that resolves to a
5935 symbol plus offset, the relocation is generated in the given symbol's section.
5936 @var{expression}, if present, must resolve to a symbol plus addend or to an
5937 absolute value, but note that not all targets support an addend. e.g. ELF REL
5938 targets such as i386 store an addend in the section contents rather than in the
5939 relocation. This low level interface does not support addends stored in the
5943 @section @code{.rept @var{count}}
5945 @cindex @code{rept} directive
5946 Repeat the sequence of lines between the @code{.rept} directive and the next
5947 @code{.endr} directive @var{count} times.
5949 For example, assembling
5957 is equivalent to assembling
5966 @section @code{.sbttl "@var{subheading}"}
5968 @cindex @code{sbttl} directive
5969 @cindex subtitles for listings
5970 @cindex listing control: subtitle
5971 Use @var{subheading} as the title (third line, immediately after the
5972 title line) when generating assembly listings.
5974 This directive affects subsequent pages, as well as the current page if
5975 it appears within ten lines of the top of a page.
5979 @section @code{.scl @var{class}}
5981 @cindex @code{scl} directive
5982 @cindex symbol storage class (COFF)
5983 @cindex COFF symbol storage class
5984 Set the storage-class value for a symbol. This directive may only be
5985 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
5986 whether a symbol is static or external, or it may record further
5987 symbolic debugging information.
5990 The @samp{.scl} directive is primarily associated with COFF output; when
5991 configured to generate @code{b.out} output format, @command{@value{AS}}
5992 accepts this directive but ignores it.
5998 @section @code{.section @var{name}}
6000 @cindex named section
6001 Use the @code{.section} directive to assemble the following code into a section
6004 This directive is only supported for targets that actually support arbitrarily
6005 named sections; on @code{a.out} targets, for example, it is not accepted, even
6006 with a standard @code{a.out} section name.
6010 @c only print the extra heading if both COFF and ELF are set
6011 @subheading COFF Version
6014 @cindex @code{section} directive (COFF version)
6015 For COFF targets, the @code{.section} directive is used in one of the following
6019 .section @var{name}[, "@var{flags}"]
6020 .section @var{name}[, @var{subsection}]
6023 If the optional argument is quoted, it is taken as flags to use for the
6024 section. Each flag is a single character. The following flags are recognized:
6027 bss section (uninitialized data)
6029 section is not loaded
6035 exclude section from linking
6041 shared section (meaningful for PE targets)
6043 ignored. (For compatibility with the ELF version)
6045 section is not readable (meaningful for PE targets)
6047 single-digit power-of-two section alignment (GNU extension)
6050 If no flags are specified, the default flags depend upon the section name. If
6051 the section name is not recognized, the default will be for the section to be
6052 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
6053 from the section, rather than adding them, so if they are used on their own it
6054 will be as if no flags had been specified at all.
6056 If the optional argument to the @code{.section} directive is not quoted, it is
6057 taken as a subsection number (@pxref{Sub-Sections}).
6062 @c only print the extra heading if both COFF and ELF are set
6063 @subheading ELF Version
6066 @cindex Section Stack
6067 This is one of the ELF section stack manipulation directives. The others are
6068 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
6069 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
6070 @code{.previous} (@pxref{Previous}).
6072 @cindex @code{section} directive (ELF version)
6073 For ELF targets, the @code{.section} directive is used like this:
6076 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]]
6079 The optional @var{flags} argument is a quoted string which may contain any
6080 combination of the following characters:
6083 section is allocatable
6085 section is excluded from executable and shared library.
6089 section is executable
6091 section is mergeable
6093 section contains zero terminated strings
6095 section is a member of a section group
6097 section is used for thread-local-storage
6099 section is a member of the previously-current section's group, if any
6102 The optional @var{type} argument may contain one of the following constants:
6105 section contains data
6107 section does not contain data (i.e., section only occupies space)
6109 section contains data which is used by things other than the program
6111 section contains an array of pointers to init functions
6113 section contains an array of pointers to finish functions
6114 @item @@preinit_array
6115 section contains an array of pointers to pre-init functions
6118 Many targets only support the first three section types.
6120 Note on targets where the @code{@@} character is the start of a comment (eg
6121 ARM) then another character is used instead. For example the ARM port uses the
6124 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
6125 be specified as well as an extra argument---@var{entsize}---like this:
6128 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
6131 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
6132 constants, each @var{entsize} octets long. Sections with both @code{M} and
6133 @code{S} must contain zero terminated strings where each character is
6134 @var{entsize} bytes long. The linker may remove duplicates within sections with
6135 the same name, same entity size and same flags. @var{entsize} must be an
6136 absolute expression. For sections with both @code{M} and @code{S}, a string
6137 which is a suffix of a larger string is considered a duplicate. Thus
6138 @code{"def"} will be merged with @code{"abcdef"}; A reference to the first
6139 @code{"def"} will be changed to a reference to @code{"abcdef"+3}.
6141 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
6142 be present along with an additional field like this:
6145 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
6148 The @var{GroupName} field specifies the name of the section group to which this
6149 particular section belongs. The optional linkage field can contain:
6152 indicates that only one copy of this section should be retained
6157 Note: if both the @var{M} and @var{G} flags are present then the fields for
6158 the Merge flag should come first, like this:
6161 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
6164 If @var{flags} contains the @code{?} symbol then it may not also contain the
6165 @code{G} symbol and the @var{GroupName} or @var{linkage} fields should not be
6166 present. Instead, @code{?} says to consider the section that's current before
6167 this directive. If that section used @code{G}, then the new section will use
6168 @code{G} with those same @var{GroupName} and @var{linkage} fields implicitly.
6169 If not, then the @code{?} symbol has no effect.
6171 If no flags are specified, the default flags depend upon the section name. If
6172 the section name is not recognized, the default will be for the section to have
6173 none of the above flags: it will not be allocated in memory, nor writable, nor
6174 executable. The section will contain data.
6176 For ELF targets, the assembler supports another type of @code{.section}
6177 directive for compatibility with the Solaris assembler:
6180 .section "@var{name}"[, @var{flags}...]
6183 Note that the section name is quoted. There may be a sequence of comma
6187 section is allocatable
6191 section is executable
6193 section is excluded from executable and shared library.
6195 section is used for thread local storage
6198 This directive replaces the current section and subsection. See the
6199 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
6200 some examples of how this directive and the other section stack directives
6206 @section @code{.set @var{symbol}, @var{expression}}
6208 @cindex @code{set} directive
6209 @cindex symbol value, setting
6210 Set the value of @var{symbol} to @var{expression}. This
6211 changes @var{symbol}'s value and type to conform to
6212 @var{expression}. If @var{symbol} was flagged as external, it remains
6213 flagged (@pxref{Symbol Attributes}).
6215 You may @code{.set} a symbol many times in the same assembly.
6217 If you @code{.set} a global symbol, the value stored in the object
6218 file is the last value stored into it.
6221 On Z80 @code{set} is a real instruction, use
6222 @samp{@var{symbol} defl @var{expression}} instead.
6226 @section @code{.short @var{expressions}}
6228 @cindex @code{short} directive
6230 @code{.short} is normally the same as @samp{.word}.
6231 @xref{Word,,@code{.word}}.
6233 In some configurations, however, @code{.short} and @code{.word} generate
6234 numbers of different lengths. @xref{Machine Dependencies}.
6238 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
6241 This expects zero or more @var{expressions}, and emits
6242 a 16 bit number for each.
6247 @section @code{.single @var{flonums}}
6249 @cindex @code{single} directive
6250 @cindex floating point numbers (single)
6251 This directive assembles zero or more flonums, separated by commas. It
6252 has the same effect as @code{.float}.
6254 The exact kind of floating point numbers emitted depends on how
6255 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
6259 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
6260 numbers in @sc{ieee} format.
6266 @section @code{.size}
6268 This directive is used to set the size associated with a symbol.
6272 @c only print the extra heading if both COFF and ELF are set
6273 @subheading COFF Version
6276 @cindex @code{size} directive (COFF version)
6277 For COFF targets, the @code{.size} directive is only permitted inside
6278 @code{.def}/@code{.endef} pairs. It is used like this:
6281 .size @var{expression}
6285 @samp{.size} is only meaningful when generating COFF format output; when
6286 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6293 @c only print the extra heading if both COFF and ELF are set
6294 @subheading ELF Version
6297 @cindex @code{size} directive (ELF version)
6298 For ELF targets, the @code{.size} directive is used like this:
6301 .size @var{name} , @var{expression}
6304 This directive sets the size associated with a symbol @var{name}.
6305 The size in bytes is computed from @var{expression} which can make use of label
6306 arithmetic. This directive is typically used to set the size of function
6311 @ifclear no-space-dir
6313 @section @code{.skip @var{size} , @var{fill}}
6315 @cindex @code{skip} directive
6316 @cindex filling memory
6317 This directive emits @var{size} bytes, each of value @var{fill}. Both
6318 @var{size} and @var{fill} are absolute expressions. If the comma and
6319 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
6324 @section @code{.sleb128 @var{expressions}}
6326 @cindex @code{sleb128} directive
6327 @var{sleb128} stands for ``signed little endian base 128.'' This is a
6328 compact, variable length representation of numbers used by the DWARF
6329 symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}.
6331 @ifclear no-space-dir
6333 @section @code{.space @var{size} , @var{fill}}
6335 @cindex @code{space} directive
6336 @cindex filling memory
6337 This directive emits @var{size} bytes, each of value @var{fill}. Both
6338 @var{size} and @var{fill} are absolute expressions. If the comma
6339 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
6344 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
6345 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
6346 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
6347 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
6355 @section @code{.stabd, .stabn, .stabs}
6357 @cindex symbolic debuggers, information for
6358 @cindex @code{stab@var{x}} directives
6359 There are three directives that begin @samp{.stab}.
6360 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
6361 The symbols are not entered in the @command{@value{AS}} hash table: they
6362 cannot be referenced elsewhere in the source file.
6363 Up to five fields are required:
6367 This is the symbol's name. It may contain any character except
6368 @samp{\000}, so is more general than ordinary symbol names. Some
6369 debuggers used to code arbitrarily complex structures into symbol names
6373 An absolute expression. The symbol's type is set to the low 8 bits of
6374 this expression. Any bit pattern is permitted, but @code{@value{LD}}
6375 and debuggers choke on silly bit patterns.
6378 An absolute expression. The symbol's ``other'' attribute is set to the
6379 low 8 bits of this expression.
6382 An absolute expression. The symbol's descriptor is set to the low 16
6383 bits of this expression.
6386 An absolute expression which becomes the symbol's value.
6389 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
6390 or @code{.stabs} statement, the symbol has probably already been created;
6391 you get a half-formed symbol in your object file. This is
6392 compatible with earlier assemblers!
6395 @cindex @code{stabd} directive
6396 @item .stabd @var{type} , @var{other} , @var{desc}
6398 The ``name'' of the symbol generated is not even an empty string.
6399 It is a null pointer, for compatibility. Older assemblers used a
6400 null pointer so they didn't waste space in object files with empty
6403 The symbol's value is set to the location counter,
6404 relocatably. When your program is linked, the value of this symbol
6405 is the address of the location counter when the @code{.stabd} was
6408 @cindex @code{stabn} directive
6409 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
6410 The name of the symbol is set to the empty string @code{""}.
6412 @cindex @code{stabs} directive
6413 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
6414 All five fields are specified.
6420 @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
6421 "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
6423 @cindex string, copying to object file
6424 @cindex string8, copying to object file
6425 @cindex string16, copying to object file
6426 @cindex string32, copying to object file
6427 @cindex string64, copying to object file
6428 @cindex @code{string} directive
6429 @cindex @code{string8} directive
6430 @cindex @code{string16} directive
6431 @cindex @code{string32} directive
6432 @cindex @code{string64} directive
6434 Copy the characters in @var{str} to the object file. You may specify more than
6435 one string to copy, separated by commas. Unless otherwise specified for a
6436 particular machine, the assembler marks the end of each string with a 0 byte.
6437 You can use any of the escape sequences described in @ref{Strings,,Strings}.
6439 The variants @code{string16}, @code{string32} and @code{string64} differ from
6440 the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
6441 copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
6442 are stored in target endianness byte order.
6448 .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
6449 .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
6454 @section @code{.struct @var{expression}}
6456 @cindex @code{struct} directive
6457 Switch to the absolute section, and set the section offset to @var{expression},
6458 which must be an absolute expression. You might use this as follows:
6467 This would define the symbol @code{field1} to have the value 0, the symbol
6468 @code{field2} to have the value 4, and the symbol @code{field3} to have the
6469 value 8. Assembly would be left in the absolute section, and you would need to
6470 use a @code{.section} directive of some sort to change to some other section
6471 before further assembly.
6475 @section @code{.subsection @var{name}}
6477 @cindex @code{subsection} directive
6478 @cindex Section Stack
6479 This is one of the ELF section stack manipulation directives. The others are
6480 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
6481 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6484 This directive replaces the current subsection with @code{name}. The current
6485 section is not changed. The replaced subsection is put onto the section stack
6486 in place of the then current top of stack subsection.
6491 @section @code{.symver}
6492 @cindex @code{symver} directive
6493 @cindex symbol versioning
6494 @cindex versions of symbols
6495 Use the @code{.symver} directive to bind symbols to specific version nodes
6496 within a source file. This is only supported on ELF platforms, and is
6497 typically used when assembling files to be linked into a shared library.
6498 There are cases where it may make sense to use this in objects to be bound
6499 into an application itself so as to override a versioned symbol from a
6502 For ELF targets, the @code{.symver} directive can be used like this:
6504 .symver @var{name}, @var{name2@@nodename}
6506 If the symbol @var{name} is defined within the file
6507 being assembled, the @code{.symver} directive effectively creates a symbol
6508 alias with the name @var{name2@@nodename}, and in fact the main reason that we
6509 just don't try and create a regular alias is that the @var{@@} character isn't
6510 permitted in symbol names. The @var{name2} part of the name is the actual name
6511 of the symbol by which it will be externally referenced. The name @var{name}
6512 itself is merely a name of convenience that is used so that it is possible to
6513 have definitions for multiple versions of a function within a single source
6514 file, and so that the compiler can unambiguously know which version of a
6515 function is being mentioned. The @var{nodename} portion of the alias should be
6516 the name of a node specified in the version script supplied to the linker when
6517 building a shared library. If you are attempting to override a versioned
6518 symbol from a shared library, then @var{nodename} should correspond to the
6519 nodename of the symbol you are trying to override.
6521 If the symbol @var{name} is not defined within the file being assembled, all
6522 references to @var{name} will be changed to @var{name2@@nodename}. If no
6523 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
6526 Another usage of the @code{.symver} directive is:
6528 .symver @var{name}, @var{name2@@@@nodename}
6530 In this case, the symbol @var{name} must exist and be defined within
6531 the file being assembled. It is similar to @var{name2@@nodename}. The
6532 difference is @var{name2@@@@nodename} will also be used to resolve
6533 references to @var{name2} by the linker.
6535 The third usage of the @code{.symver} directive is:
6537 .symver @var{name}, @var{name2@@@@@@nodename}
6539 When @var{name} is not defined within the
6540 file being assembled, it is treated as @var{name2@@nodename}. When
6541 @var{name} is defined within the file being assembled, the symbol
6542 name, @var{name}, will be changed to @var{name2@@@@nodename}.
6547 @section @code{.tag @var{structname}}
6549 @cindex COFF structure debugging
6550 @cindex structure debugging, COFF
6551 @cindex @code{tag} directive
6552 This directive is generated by compilers to include auxiliary debugging
6553 information in the symbol table. It is only permitted inside
6554 @code{.def}/@code{.endef} pairs. Tags are used to link structure
6555 definitions in the symbol table with instances of those structures.
6558 @samp{.tag} is only used when generating COFF format output; when
6559 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6565 @section @code{.text @var{subsection}}
6567 @cindex @code{text} directive
6568 Tells @command{@value{AS}} to assemble the following statements onto the end of
6569 the text subsection numbered @var{subsection}, which is an absolute
6570 expression. If @var{subsection} is omitted, subsection number zero
6574 @section @code{.title "@var{heading}"}
6576 @cindex @code{title} directive
6577 @cindex listing control: title line
6578 Use @var{heading} as the title (second line, immediately after the
6579 source file name and pagenumber) when generating assembly listings.
6581 This directive affects subsequent pages, as well as the current page if
6582 it appears within ten lines of the top of a page.
6586 @section @code{.type}
6588 This directive is used to set the type of a symbol.
6592 @c only print the extra heading if both COFF and ELF are set
6593 @subheading COFF Version
6596 @cindex COFF symbol type
6597 @cindex symbol type, COFF
6598 @cindex @code{type} directive (COFF version)
6599 For COFF targets, this directive is permitted only within
6600 @code{.def}/@code{.endef} pairs. It is used like this:
6606 This records the integer @var{int} as the type attribute of a symbol table
6610 @samp{.type} is associated only with COFF format output; when
6611 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
6612 directive but ignores it.
6618 @c only print the extra heading if both COFF and ELF are set
6619 @subheading ELF Version
6622 @cindex ELF symbol type
6623 @cindex symbol type, ELF
6624 @cindex @code{type} directive (ELF version)
6625 For ELF targets, the @code{.type} directive is used like this:
6628 .type @var{name} , @var{type description}
6631 This sets the type of symbol @var{name} to be either a
6632 function symbol or an object symbol. There are five different syntaxes
6633 supported for the @var{type description} field, in order to provide
6634 compatibility with various other assemblers.
6636 Because some of the characters used in these syntaxes (such as @samp{@@} and
6637 @samp{#}) are comment characters for some architectures, some of the syntaxes
6638 below do not work on all architectures. The first variant will be accepted by
6639 the GNU assembler on all architectures so that variant should be used for
6640 maximum portability, if you do not need to assemble your code with other
6643 The syntaxes supported are:
6646 .type <name> STT_<TYPE_IN_UPPER_CASE>
6647 .type <name>,#<type>
6648 .type <name>,@@<type>
6649 .type <name>,%<type>
6650 .type <name>,"<type>"
6653 The types supported are:
6658 Mark the symbol as being a function name.
6661 @itemx gnu_indirect_function
6662 Mark the symbol as an indirect function when evaluated during reloc
6663 processing. (This is only supported on assemblers targeting GNU systems).
6667 Mark the symbol as being a data object.
6671 Mark the symbol as being a thead-local data object.
6675 Mark the symbol as being a common data object.
6679 Does not mark the symbol in any way. It is supported just for completeness.
6681 @item gnu_unique_object
6682 Marks the symbol as being a globally unique data object. The dynamic linker
6683 will make sure that in the entire process there is just one symbol with this
6684 name and type in use. (This is only supported on assemblers targeting GNU
6689 Note: Some targets support extra types in addition to those listed above.
6695 @section @code{.uleb128 @var{expressions}}
6697 @cindex @code{uleb128} directive
6698 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
6699 compact, variable length representation of numbers used by the DWARF
6700 symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}.
6704 @section @code{.val @var{addr}}
6706 @cindex @code{val} directive
6707 @cindex COFF value attribute
6708 @cindex value attribute, COFF
6709 This directive, permitted only within @code{.def}/@code{.endef} pairs,
6710 records the address @var{addr} as the value attribute of a symbol table
6714 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
6715 configured for @code{b.out}, it accepts this directive but ignores it.
6721 @section @code{.version "@var{string}"}
6723 @cindex @code{version} directive
6724 This directive creates a @code{.note} section and places into it an ELF
6725 formatted note of type NT_VERSION. The note's name is set to @code{string}.
6730 @section @code{.vtable_entry @var{table}, @var{offset}}
6732 @cindex @code{vtable_entry} directive
6733 This directive finds or creates a symbol @code{table} and creates a
6734 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
6737 @section @code{.vtable_inherit @var{child}, @var{parent}}
6739 @cindex @code{vtable_inherit} directive
6740 This directive finds the symbol @code{child} and finds or creates the symbol
6741 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
6742 parent whose addend is the value of the child symbol. As a special case the
6743 parent name of @code{0} is treated as referring to the @code{*ABS*} section.
6747 @section @code{.warning "@var{string}"}
6748 @cindex warning directive
6749 Similar to the directive @code{.error}
6750 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
6753 @section @code{.weak @var{names}}
6755 @cindex @code{weak} directive
6756 This directive sets the weak attribute on the comma separated list of symbol
6757 @code{names}. If the symbols do not already exist, they will be created.
6759 On COFF targets other than PE, weak symbols are a GNU extension. This
6760 directive sets the weak attribute on the comma separated list of symbol
6761 @code{names}. If the symbols do not already exist, they will be created.
6763 On the PE target, weak symbols are supported natively as weak aliases.
6764 When a weak symbol is created that is not an alias, GAS creates an
6765 alternate symbol to hold the default value.
6768 @section @code{.weakref @var{alias}, @var{target}}
6770 @cindex @code{weakref} directive
6771 This directive creates an alias to the target symbol that enables the symbol to
6772 be referenced with weak-symbol semantics, but without actually making it weak.
6773 If direct references or definitions of the symbol are present, then the symbol
6774 will not be weak, but if all references to it are through weak references, the
6775 symbol will be marked as weak in the symbol table.
6777 The effect is equivalent to moving all references to the alias to a separate
6778 assembly source file, renaming the alias to the symbol in it, declaring the
6779 symbol as weak there, and running a reloadable link to merge the object files
6780 resulting from the assembly of the new source file and the old source file that
6781 had the references to the alias removed.
6783 The alias itself never makes to the symbol table, and is entirely handled
6784 within the assembler.
6787 @section @code{.word @var{expressions}}
6789 @cindex @code{word} directive
6790 This directive expects zero or more @var{expressions}, of any section,
6791 separated by commas.
6794 For each expression, @command{@value{AS}} emits a 32-bit number.
6797 For each expression, @command{@value{AS}} emits a 16-bit number.
6802 The size of the number emitted, and its byte order,
6803 depend on what target computer the assembly is for.
6806 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
6807 @c happen---32-bit addressability, period; no long/short jumps.
6808 @ifset DIFF-TBL-KLUGE
6809 @cindex difference tables altered
6810 @cindex altered difference tables
6812 @emph{Warning: Special Treatment to support Compilers}
6816 Machines with a 32-bit address space, but that do less than 32-bit
6817 addressing, require the following special treatment. If the machine of
6818 interest to you does 32-bit addressing (or doesn't require it;
6819 @pxref{Machine Dependencies}), you can ignore this issue.
6822 In order to assemble compiler output into something that works,
6823 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
6824 Directives of the form @samp{.word sym1-sym2} are often emitted by
6825 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
6826 directive of the form @samp{.word sym1-sym2}, and the difference between
6827 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
6828 creates a @dfn{secondary jump table}, immediately before the next label.
6829 This secondary jump table is preceded by a short-jump to the
6830 first byte after the secondary table. This short-jump prevents the flow
6831 of control from accidentally falling into the new table. Inside the
6832 table is a long-jump to @code{sym2}. The original @samp{.word}
6833 contains @code{sym1} minus the address of the long-jump to
6836 If there were several occurrences of @samp{.word sym1-sym2} before the
6837 secondary jump table, all of them are adjusted. If there was a
6838 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
6839 long-jump to @code{sym4} is included in the secondary jump table,
6840 and the @code{.word} directives are adjusted to contain @code{sym3}
6841 minus the address of the long-jump to @code{sym4}; and so on, for as many
6842 entries in the original jump table as necessary.
6845 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
6846 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
6847 assembly language programmers.
6850 @c end DIFF-TBL-KLUGE
6853 @section Deprecated Directives
6855 @cindex deprecated directives
6856 @cindex obsolescent directives
6857 One day these directives won't work.
6858 They are included for compatibility with older assemblers.
6865 @node Object Attributes
6866 @chapter Object Attributes
6867 @cindex object attributes
6869 @command{@value{AS}} assembles source files written for a specific architecture
6870 into object files for that architecture. But not all object files are alike.
6871 Many architectures support incompatible variations. For instance, floating
6872 point arguments might be passed in floating point registers if the object file
6873 requires hardware floating point support---or floating point arguments might be
6874 passed in integer registers if the object file supports processors with no
6875 hardware floating point unit. Or, if two objects are built for different
6876 generations of the same architecture, the combination may require the
6877 newer generation at run-time.
6879 This information is useful during and after linking. At link time,
6880 @command{@value{LD}} can warn about incompatible object files. After link
6881 time, tools like @command{gdb} can use it to process the linked file
6884 Compatibility information is recorded as a series of object attributes. Each
6885 attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
6886 string, and indicates who sets the meaning of the tag. The tag is an integer,
6887 and indicates what property the attribute describes. The value may be a string
6888 or an integer, and indicates how the property affects this object. Missing
6889 attributes are the same as attributes with a zero value or empty string value.
6891 Object attributes were developed as part of the ABI for the ARM Architecture.
6892 The file format is documented in @cite{ELF for the ARM Architecture}.
6895 * GNU Object Attributes:: @sc{gnu} Object Attributes
6896 * Defining New Object Attributes:: Defining New Object Attributes
6899 @node GNU Object Attributes
6900 @section @sc{gnu} Object Attributes
6902 The @code{.gnu_attribute} directive records an object attribute
6903 with vendor @samp{gnu}.
6905 Except for @samp{Tag_compatibility}, which has both an integer and a string for
6906 its value, @sc{gnu} attributes have a string value if the tag number is odd and
6907 an integer value if the tag number is even. The second bit (@code{@var{tag} &
6908 2} is set for architecture-independent attributes and clear for
6909 architecture-dependent ones.
6911 @subsection Common @sc{gnu} attributes
6913 These attributes are valid on all architectures.
6916 @item Tag_compatibility (32)
6917 The compatibility attribute takes an integer flag value and a vendor name. If
6918 the flag value is 0, the file is compatible with other toolchains. If it is 1,
6919 then the file is only compatible with the named toolchain. If it is greater
6920 than 1, the file can only be processed by other toolchains under some private
6921 arrangement indicated by the flag value and the vendor name.
6924 @subsection MIPS Attributes
6927 @item Tag_GNU_MIPS_ABI_FP (4)
6928 The floating-point ABI used by this object file. The value will be:
6932 0 for files not affected by the floating-point ABI.
6934 1 for files using the hardware floating-point with a standard double-precision
6937 2 for files using the hardware floating-point ABI with a single-precision FPU.
6939 3 for files using the software floating-point ABI.
6941 4 for files using the hardware floating-point ABI with 64-bit wide
6942 double-precision floating-point registers and 32-bit wide general
6947 @subsection PowerPC Attributes
6950 @item Tag_GNU_Power_ABI_FP (4)
6951 The floating-point ABI used by this object file. The value will be:
6955 0 for files not affected by the floating-point ABI.
6957 1 for files using double-precision hardware floating-point ABI.
6959 2 for files using the software floating-point ABI.
6961 3 for files using single-precision hardware floating-point ABI.
6964 @item Tag_GNU_Power_ABI_Vector (8)
6965 The vector ABI used by this object file. The value will be:
6969 0 for files not affected by the vector ABI.
6971 1 for files using general purpose registers to pass vectors.
6973 2 for files using AltiVec registers to pass vectors.
6975 3 for files using SPE registers to pass vectors.
6979 @node Defining New Object Attributes
6980 @section Defining New Object Attributes
6982 If you want to define a new @sc{gnu} object attribute, here are the places you
6983 will need to modify. New attributes should be discussed on the @samp{binutils}
6988 This manual, which is the official register of attributes.
6990 The header for your architecture @file{include/elf}, to define the tag.
6992 The @file{bfd} support file for your architecture, to merge the attribute
6993 and issue any appropriate link warnings.
6995 Test cases in @file{ld/testsuite} for merging and link warnings.
6997 @file{binutils/readelf.c} to display your attribute.
6999 GCC, if you want the compiler to mark the attribute automatically.
7005 @node Machine Dependencies
7006 @chapter Machine Dependent Features
7008 @cindex machine dependencies
7009 The machine instruction sets are (almost by definition) different on
7010 each machine where @command{@value{AS}} runs. Floating point representations
7011 vary as well, and @command{@value{AS}} often supports a few additional
7012 directives or command-line options for compatibility with other
7013 assemblers on a particular platform. Finally, some versions of
7014 @command{@value{AS}} support special pseudo-instructions for branch
7017 This chapter discusses most of these differences, though it does not
7018 include details on any machine's instruction set. For details on that
7019 subject, see the hardware manufacturer's manual.
7023 * AArch64-Dependent:: AArch64 Dependent Features
7026 * Alpha-Dependent:: Alpha Dependent Features
7029 * ARC-Dependent:: ARC Dependent Features
7032 * ARM-Dependent:: ARM Dependent Features
7035 * AVR-Dependent:: AVR Dependent Features
7038 * Blackfin-Dependent:: Blackfin Dependent Features
7041 * CR16-Dependent:: CR16 Dependent Features
7044 * CRIS-Dependent:: CRIS Dependent Features
7047 * D10V-Dependent:: D10V Dependent Features
7050 * D30V-Dependent:: D30V Dependent Features
7053 * Epiphany-Dependent:: EPIPHANY Dependent Features
7056 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7059 * HPPA-Dependent:: HPPA Dependent Features
7062 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
7065 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
7068 * i860-Dependent:: Intel 80860 Dependent Features
7071 * i960-Dependent:: Intel 80960 Dependent Features
7074 * IA-64-Dependent:: Intel IA-64 Dependent Features
7077 * IP2K-Dependent:: IP2K Dependent Features
7080 * LM32-Dependent:: LM32 Dependent Features
7083 * M32C-Dependent:: M32C Dependent Features
7086 * M32R-Dependent:: M32R Dependent Features
7089 * M68K-Dependent:: M680x0 Dependent Features
7092 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
7095 * Meta-Dependent :: Meta Dependent Features
7098 * MicroBlaze-Dependent:: MICROBLAZE Dependent Features
7101 * MIPS-Dependent:: MIPS Dependent Features
7104 * MMIX-Dependent:: MMIX Dependent Features
7107 * MSP430-Dependent:: MSP430 Dependent Features
7110 * NiosII-Dependent:: Altera Nios II Dependent Features
7113 * NS32K-Dependent:: NS32K Dependent Features
7116 * SH-Dependent:: Renesas / SuperH SH Dependent Features
7117 * SH64-Dependent:: SuperH SH64 Dependent Features
7120 * PDP-11-Dependent:: PDP-11 Dependent Features
7123 * PJ-Dependent:: picoJava Dependent Features
7126 * PPC-Dependent:: PowerPC Dependent Features
7129 * RL78-Dependent:: RL78 Dependent Features
7132 * RX-Dependent:: RX Dependent Features
7135 * S/390-Dependent:: IBM S/390 Dependent Features
7138 * SCORE-Dependent:: SCORE Dependent Features
7141 * Sparc-Dependent:: SPARC Dependent Features
7144 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
7147 * TIC6X-Dependent :: TI TMS320C6x Dependent Features
7150 * TILE-Gx-Dependent :: Tilera TILE-Gx Dependent Features
7153 * TILEPro-Dependent :: Tilera TILEPro Dependent Features
7156 * V850-Dependent:: V850 Dependent Features
7159 * XGATE-Dependent:: XGATE Features
7162 * XSTORMY16-Dependent:: XStormy16 Dependent Features
7165 * Xtensa-Dependent:: Xtensa Dependent Features
7168 * Z80-Dependent:: Z80 Dependent Features
7171 * Z8000-Dependent:: Z8000 Dependent Features
7174 * Vax-Dependent:: VAX Dependent Features
7181 @c The following major nodes are *sections* in the GENERIC version, *chapters*
7182 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
7183 @c peculiarity: to preserve cross-references, there must be a node called
7184 @c "Machine Dependencies". Hence the conditional nodenames in each
7185 @c major node below. Node defaulting in makeinfo requires adjacency of
7186 @c node and sectioning commands; hence the repetition of @chapter BLAH
7187 @c in both conditional blocks.
7190 @include c-aarch64.texi
7194 @include c-alpha.texi
7210 @include c-bfin.texi
7214 @include c-cr16.texi
7218 @include c-cris.texi
7223 @node Machine Dependencies
7224 @chapter Machine Dependent Features
7226 The machine instruction sets are different on each Renesas chip family,
7227 and there are also some syntax differences among the families. This
7228 chapter describes the specific @command{@value{AS}} features for each
7232 * H8/300-Dependent:: Renesas H8/300 Dependent Features
7233 * SH-Dependent:: Renesas SH Dependent Features
7240 @include c-d10v.texi
7244 @include c-d30v.texi
7248 @include c-epiphany.texi
7252 @include c-h8300.texi
7256 @include c-hppa.texi
7260 @include c-i370.texi
7264 @include c-i386.texi
7268 @include c-i860.texi
7272 @include c-i960.texi
7276 @include c-ia64.texi
7280 @include c-ip2k.texi
7284 @include c-lm32.texi
7288 @include c-m32c.texi
7292 @include c-m32r.texi
7296 @include c-m68k.texi
7300 @include c-m68hc11.texi
7304 @include c-metag.texi
7308 @include c-microblaze.texi
7312 @include c-mips.texi
7316 @include c-mmix.texi
7320 @include c-msp430.texi
7324 @include c-nios2.texi
7328 @include c-ns32k.texi
7332 @include c-pdp11.texi
7344 @include c-rl78.texi
7352 @include c-s390.texi
7356 @include c-score.texi
7361 @include c-sh64.texi
7365 @include c-sparc.texi
7369 @include c-tic54x.texi
7373 @include c-tic6x.texi
7377 @include c-tilegx.texi
7381 @include c-tilepro.texi
7397 @include c-v850.texi
7401 @include c-xgate.texi
7405 @include c-xstormy16.texi
7409 @include c-xtensa.texi
7413 @c reverse effect of @down at top of generic Machine-Dep chapter
7417 @node Reporting Bugs
7418 @chapter Reporting Bugs
7419 @cindex bugs in assembler
7420 @cindex reporting bugs in assembler
7422 Your bug reports play an essential role in making @command{@value{AS}} reliable.
7424 Reporting a bug may help you by bringing a solution to your problem, or it may
7425 not. But in any case the principal function of a bug report is to help the
7426 entire community by making the next version of @command{@value{AS}} work better.
7427 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
7429 In order for a bug report to serve its purpose, you must include the
7430 information that enables us to fix the bug.
7433 * Bug Criteria:: Have you found a bug?
7434 * Bug Reporting:: How to report bugs
7438 @section Have You Found a Bug?
7439 @cindex bug criteria
7441 If you are not sure whether you have found a bug, here are some guidelines:
7444 @cindex fatal signal
7445 @cindex assembler crash
7446 @cindex crash of assembler
7448 If the assembler gets a fatal signal, for any input whatever, that is a
7449 @command{@value{AS}} bug. Reliable assemblers never crash.
7451 @cindex error on valid input
7453 If @command{@value{AS}} produces an error message for valid input, that is a bug.
7455 @cindex invalid input
7457 If @command{@value{AS}} does not produce an error message for invalid input, that
7458 is a bug. However, you should note that your idea of ``invalid input'' might
7459 be our idea of ``an extension'' or ``support for traditional practice''.
7462 If you are an experienced user of assemblers, your suggestions for improvement
7463 of @command{@value{AS}} are welcome in any case.
7467 @section How to Report Bugs
7469 @cindex assembler bugs, reporting
7471 A number of companies and individuals offer support for @sc{gnu} products. If
7472 you obtained @command{@value{AS}} from a support organization, we recommend you
7473 contact that organization first.
7475 You can find contact information for many support companies and
7476 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
7480 In any event, we also recommend that you send bug reports for @command{@value{AS}}
7484 The fundamental principle of reporting bugs usefully is this:
7485 @strong{report all the facts}. If you are not sure whether to state a
7486 fact or leave it out, state it!
7488 Often people omit facts because they think they know what causes the problem
7489 and assume that some details do not matter. Thus, you might assume that the
7490 name of a symbol you use in an example does not matter. Well, probably it does
7491 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
7492 happens to fetch from the location where that name is stored in memory;
7493 perhaps, if the name were different, the contents of that location would fool
7494 the assembler into doing the right thing despite the bug. Play it safe and
7495 give a specific, complete example. That is the easiest thing for you to do,
7496 and the most helpful.
7498 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
7499 it is new to us. Therefore, always write your bug reports on the assumption
7500 that the bug has not been reported previously.
7502 Sometimes people give a few sketchy facts and ask, ``Does this ring a
7503 bell?'' This cannot help us fix a bug, so it is basically useless. We
7504 respond by asking for enough details to enable us to investigate.
7505 You might as well expedite matters by sending them to begin with.
7507 To enable us to fix the bug, you should include all these things:
7511 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
7512 it with the @samp{--version} argument.
7514 Without this, we will not know whether there is any point in looking for
7515 the bug in the current version of @command{@value{AS}}.
7518 Any patches you may have applied to the @command{@value{AS}} source.
7521 The type of machine you are using, and the operating system name and
7525 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
7529 The command arguments you gave the assembler to assemble your example and
7530 observe the bug. To guarantee you will not omit something important, list them
7531 all. A copy of the Makefile (or the output from make) is sufficient.
7533 If we were to try to guess the arguments, we would probably guess wrong
7534 and then we might not encounter the bug.
7537 A complete input file that will reproduce the bug. If the bug is observed when
7538 the assembler is invoked via a compiler, send the assembler source, not the
7539 high level language source. Most compilers will produce the assembler source
7540 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
7541 the options @samp{-v --save-temps}; this will save the assembler source in a
7542 file with an extension of @file{.s}, and also show you exactly how
7543 @command{@value{AS}} is being run.
7546 A description of what behavior you observe that you believe is
7547 incorrect. For example, ``It gets a fatal signal.''
7549 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
7550 will certainly notice it. But if the bug is incorrect output, we might not
7551 notice unless it is glaringly wrong. You might as well not give us a chance to
7554 Even if the problem you experience is a fatal signal, you should still say so
7555 explicitly. Suppose something strange is going on, such as, your copy of
7556 @command{@value{AS}} is out of sync, or you have encountered a bug in the C
7557 library on your system. (This has happened!) Your copy might crash and ours
7558 would not. If you told us to expect a crash, then when ours fails to crash, we
7559 would know that the bug was not happening for us. If you had not told us to
7560 expect a crash, then we would not be able to draw any conclusion from our
7564 If you wish to suggest changes to the @command{@value{AS}} source, send us context
7565 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
7566 option. Always send diffs from the old file to the new file. If you even
7567 discuss something in the @command{@value{AS}} source, refer to it by context, not
7570 The line numbers in our development sources will not match those in your
7571 sources. Your line numbers would convey no useful information to us.
7574 Here are some things that are not necessary:
7578 A description of the envelope of the bug.
7580 Often people who encounter a bug spend a lot of time investigating
7581 which changes to the input file will make the bug go away and which
7582 changes will not affect it.
7584 This is often time consuming and not very useful, because the way we
7585 will find the bug is by running a single example under the debugger
7586 with breakpoints, not by pure deduction from a series of examples.
7587 We recommend that you save your time for something else.
7589 Of course, if you can find a simpler example to report @emph{instead}
7590 of the original one, that is a convenience for us. Errors in the
7591 output will be easier to spot, running under the debugger will take
7592 less time, and so on.
7594 However, simplification is not vital; if you do not want to do this,
7595 report the bug anyway and send us the entire test case you used.
7598 A patch for the bug.
7600 A patch for the bug does help us if it is a good one. But do not omit
7601 the necessary information, such as the test case, on the assumption that
7602 a patch is all we need. We might see problems with your patch and decide
7603 to fix the problem another way, or we might not understand it at all.
7605 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
7606 construct an example that will make the program follow a certain path through
7607 the code. If you do not send us the example, we will not be able to construct
7608 one, so we will not be able to verify that the bug is fixed.
7610 And if we cannot understand what bug you are trying to fix, or why your
7611 patch should be an improvement, we will not install it. A test case will
7612 help us to understand.
7615 A guess about what the bug is or what it depends on.
7617 Such guesses are usually wrong. Even we cannot guess right about such
7618 things without first using the debugger to find the facts.
7621 @node Acknowledgements
7622 @chapter Acknowledgements
7624 If you have contributed to GAS and your name isn't listed here,
7625 it is not meant as a slight. We just don't know about it. Send mail to the
7626 maintainer, and we'll correct the situation. Currently
7628 the maintainer is Nick Clifton (email address @code{nickc@@redhat.com}).
7630 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
7633 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
7634 information and the 68k series machines, most of the preprocessing pass, and
7635 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
7637 K. Richard Pixley maintained GAS for a while, adding various enhancements and
7638 many bug fixes, including merging support for several processors, breaking GAS
7639 up to handle multiple object file format back ends (including heavy rewrite,
7640 testing, an integration of the coff and b.out back ends), adding configuration
7641 including heavy testing and verification of cross assemblers and file splits
7642 and renaming, converted GAS to strictly ANSI C including full prototypes, added
7643 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
7644 port (including considerable amounts of reverse engineering), a SPARC opcode
7645 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
7646 assertions and made them work, much other reorganization, cleanup, and lint.
7648 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
7649 in format-specific I/O modules.
7651 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
7652 has done much work with it since.
7654 The Intel 80386 machine description was written by Eliot Dresselhaus.
7656 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
7658 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
7659 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
7661 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
7662 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
7663 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
7664 support a.out format.
7666 Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
7667 tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
7668 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
7669 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
7672 John Gilmore built the AMD 29000 support, added @code{.include} support, and
7673 simplified the configuration of which versions accept which directives. He
7674 updated the 68k machine description so that Motorola's opcodes always produced
7675 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
7676 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
7677 cross-compilation support, and one bug in relaxation that took a week and
7678 required the proverbial one-bit fix.
7680 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
7681 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
7682 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
7683 PowerPC assembler, and made a few other minor patches.
7685 Steve Chamberlain made GAS able to generate listings.
7687 Hewlett-Packard contributed support for the HP9000/300.
7689 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
7690 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
7691 formats). This work was supported by both the Center for Software Science at
7692 the University of Utah and Cygnus Support.
7694 Support for ELF format files has been worked on by Mark Eichin of Cygnus
7695 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
7696 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
7697 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
7698 and some initial 64-bit support).
7700 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
7702 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
7703 support for openVMS/Alpha.
7705 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
7708 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
7709 Inc.@: added support for Xtensa processors.
7711 Several engineers at Cygnus Support have also provided many small bug fixes and
7712 configuration enhancements.
7714 Jon Beniston added support for the Lattice Mico32 architecture.
7716 Many others have contributed large or small bugfixes and enhancements. If
7717 you have contributed significant work and are not mentioned on this list, and
7718 want to be, let us know. Some of the history has been lost; we are not
7719 intentionally leaving anyone out.
7721 @node GNU Free Documentation License
7722 @appendix GNU Free Documentation License
7726 @unnumbered AS Index
projects / deliverable / binutils-gdb.git / blob