1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
3 @c 2001, 2002, 2003, 2004
4 @c Free Software Foundation, Inc.
5 @c UPDATE!! On future updates--
6 @c (1) check for new machine-dep cmdline options in
7 @c md_parse_option definitions in config/tc-*.c
8 @c (2) for platform-specific directives, examine md_pseudo_op
10 @c (3) for object-format specific directives, examine obj_pseudo_op
12 @c (4) portable directives in potable[] in read.c
16 @macro gcctabopt{body}
19 @c defaults, config file may override:
24 @include asconfig.texi
29 @c common OR combinations of conditions
55 @set abnormal-separator
59 @settitle Using @value{AS}
62 @settitle Using @value{AS} (@value{TARGET})
64 @setchapternewpage odd
69 @c WARE! Some of the machine-dependent sections contain tables of machine
70 @c instructions. Except in multi-column format, these tables look silly.
71 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
72 @c the multi-col format is faked within @example sections.
74 @c Again unfortunately, the natural size that fits on a page, for these tables,
75 @c is different depending on whether or not smallbook is turned on.
76 @c This matters, because of order: text flow switches columns at each page
79 @c The format faked in this source works reasonably well for smallbook,
80 @c not well for the default large-page format. This manual expects that if you
81 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
82 @c tables in question. You can turn on one without the other at your
83 @c discretion, of course.
86 @c the insn tables look just as silly in info files regardless of smallbook,
87 @c might as well show 'em anyways.
93 * As: (as). The GNU assembler.
94 * Gas: (as). The GNU assembler.
103 This file documents the GNU Assembler "@value{AS}".
105 @c man begin COPYRIGHT
106 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
108 Permission is granted to copy, distribute and/or modify this document
109 under the terms of the GNU Free Documentation License, Version 1.1
110 or any later version published by the Free Software Foundation;
111 with no Invariant Sections, with no Front-Cover Texts, and with no
112 Back-Cover Texts. A copy of the license is included in the
113 section entitled ``GNU Free Documentation License''.
118 Permission is granted to process this file through Tex and print the
119 results, provided the printed document carries copying permission
120 notice identical to this one except for the removal of this paragraph
121 (this paragraph not being relevant to the printed manual).
127 @title Using @value{AS}
128 @subtitle The @sc{gnu} Assembler
130 @subtitle for the @value{TARGET} family
133 @subtitle Version @value{VERSION}
136 The Free Software Foundation Inc. thanks The Nice Computer
137 Company of Australia for loaning Dean Elsner to write the
138 first (Vax) version of @command{as} for Project @sc{gnu}.
139 The proprietors, management and staff of TNCCA thank FSF for
140 distracting the boss while they got some work
143 @author Dean Elsner, Jay Fenlason & friends
147 \hfill {\it Using {\tt @value{AS}}}\par
148 \hfill Edited by Cygnus Support\par
150 %"boxit" macro for figures:
151 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
152 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
153 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
154 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
155 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
158 @vskip 0pt plus 1filll
159 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
161 Permission is granted to copy, distribute and/or modify this document
162 under the terms of the GNU Free Documentation License, Version 1.1
163 or any later version published by the Free Software Foundation;
164 with no Invariant Sections, with no Front-Cover Texts, and with no
165 Back-Cover Texts. A copy of the license is included in the
166 section entitled ``GNU Free Documentation License''.
172 @top Using @value{AS}
174 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version
177 This version of the file describes @command{@value{AS}} configured to generate
178 code for @value{TARGET} architectures.
181 This document is distributed under the terms of the GNU Free
182 Documentation License. A copy of the license is included in the
183 section entitled ``GNU Free Documentation License''.
186 * Overview:: Overview
187 * Invoking:: Command-Line Options
189 * Sections:: Sections and Relocation
191 * Expressions:: Expressions
192 * Pseudo Ops:: Assembler Directives
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
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 @pxref{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{cdhlns}][=@var{file}]] [@b{--alternate}] [@b{-D}]
230 [@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}] [@b{--gstabs+}]
231 [@b{--gdwarf-2}] [@b{--help}] [@b{-I} @var{dir}] [@b{-J}] [@b{-K}] [@b{-L}]
232 [@b{--listing-lhs-width}=@var{NUM}] [@b{--listing-lhs-width2}=@var{NUM}]
233 [@b{--listing-rhs-width}=@var{NUM}] [@b{--listing-cont-lines}=@var{NUM}]
234 [@b{--keep-locals}] [@b{-o} @var{objfile}] [@b{-R}] [@b{--statistics}] [@b{-v}]
235 [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}]
236 [@b{-w}] [@b{-x}] [@b{-Z}] [@b{--target-help}] [@var{target-options}]
237 [@b{--}|@var{files} @dots{}]
239 @c Target dependent options are listed below. Keep the list sorted.
240 @c Add an empty line for separation.
242 @c am29k has no machine-dependent assembler options
246 @emph{Target Alpha options:}
248 [@b{-mdebug} | @b{-no-mdebug}]
249 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
250 [@b{-F}] [@b{-32addr}]
254 @emph{Target ARC options:}
260 @emph{Target ARM options:}
261 @c Don't document the deprecated options
262 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
263 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
264 [@b{-mfpu}=@var{floating-point-format}]
265 [@b{-mfloat-abi}=@var{abi}]
266 [@b{-meabi}=@var{ver}]
269 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
270 @b{-mapcs-reentrant}]
271 [@b{-mthumb-interwork}] [@b{-moabi}] [@b{-k}]
275 @emph{Target CRIS options:}
276 [@b{--underscore} | @b{--no-underscore}]
278 [@b{--emulation=criself} | @b{--emulation=crisaout}]
279 [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}]
280 @c Deprecated -- deliberately not documented.
285 @emph{Target D10V options:}
290 @emph{Target D30V options:}
291 [@b{-O}|@b{-n}|@b{-N}]
294 @c Renesas family chips have no machine-dependent assembler options
297 @c HPPA has no machine-dependent assembler options (yet).
301 @emph{Target i386 options:}
302 [@b{--32}|@b{--64}] [@b{-n}]
306 @emph{Target i960 options:}
307 @c see md_parse_option in tc-i960.c
308 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
310 [@b{-b}] [@b{-no-relax}]
314 @emph{Target IA-64 options:}
315 [@b{-mconstant-gp}|@b{-mauto-pic}]
316 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
318 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
322 @emph{Target IP2K options:}
323 [@b{-mip2022}|@b{-mip2022ext}]
327 @emph{Target M32R options:}
328 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
333 @emph{Target M680X0 options:}
334 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
338 @emph{Target M68HC11 options:}
339 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}]
340 [@b{-mshort}|@b{-mlong}]
341 [@b{-mshort-double}|@b{-mlong-double}]
342 [@b{--force-long-branchs}] [@b{--short-branchs}]
343 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
344 [@b{--print-opcodes}] [@b{--generate-example}]
348 @emph{Target MCORE options:}
349 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
350 [@b{-mcpu=[210|340]}]
354 @emph{Target MIPS options:}
355 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
356 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
357 [@b{-non_shared}] [@b{-xgot}]
358 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
359 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
360 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
361 [@b{-mips64}] [@b{-mips64r2}]
362 [@b{-construct-floats}] [@b{-no-construct-floats}]
363 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
364 [@b{-mfix7000}] [@b{-mno-fix7000}]
365 [@b{-mips16}] [@b{-no-mips16}]
366 [@b{-mips3d}] [@b{-no-mips3d}]
367 [@b{-mdmx}] [@b{-no-mdmx}]
368 [@b{-mdebug}] [@b{-no-mdebug}]
369 [@b{-mpdr}] [@b{-mno-pdr}]
373 @emph{Target MMIX options:}
374 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
375 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
376 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
377 [@b{--linker-allocated-gregs}]
381 @emph{Target PDP11 options:}
382 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
383 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
384 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
388 @emph{Target picoJava options:}
393 @emph{Target PowerPC options:}
394 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
395 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
396 @b{-mbooke32}|@b{-mbooke64}]
397 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
398 [@b{-mregnames}|@b{-mno-regnames}]
399 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
400 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
401 [@b{-msolaris}|@b{-mno-solaris}]
405 @emph{Target SPARC options:}
406 @c The order here is important. See c-sparc.texi.
407 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
408 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
409 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
414 @emph{Target TIC54X options:}
415 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
416 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
419 @c Z8000 has no machine-dependent assembler options
423 @emph{Target Xtensa options:}
424 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
425 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
426 [@b{--[no-]transform}]
435 Turn on listings, in any of a variety of ways:
439 omit false conditionals
442 omit debugging directives
445 include high-level source
451 include macro expansions
454 omit forms processing
460 set the name of the listing file
463 You may combine these options; for example, use @samp{-aln} for assembly
464 listing without forms processing. The @samp{=file} option, if used, must be
465 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
468 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
471 Ignored. This option is accepted for script compatibility with calls to
474 @item --defsym @var{sym}=@var{value}
475 Define the symbol @var{sym} to be @var{value} before assembling the input file.
476 @var{value} must be an integer constant. As in C, a leading @samp{0x}
477 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
480 ``fast''---skip whitespace and comment preprocessing (assume source is
485 Generate debugging information for each assembler source line using whichever
486 debug format is preferred by the target. This currently means either STABS,
490 Generate stabs debugging information for each assembler line. This
491 may help debugging assembler code, if the debugger can handle it.
494 Generate stabs debugging information for each assembler line, with GNU
495 extensions that probably only gdb can handle, and that could make other
496 debuggers crash or refuse to read your program. This
497 may help debugging assembler code. Currently the only GNU extension is
498 the location of the current working directory at assembling time.
501 Generate DWARF2 debugging information for each assembler line. This
502 may help debugging assembler code, if the debugger can handle it. Note---this
503 option is only supported by some targets, not all of them.
506 Print a summary of the command line options and exit.
509 Print a summary of all target specific options and exit.
512 Add directory @var{dir} to the search list for @code{.include} directives.
515 Don't warn about signed overflow.
518 @ifclear DIFF-TBL-KLUGE
519 This option is accepted but has no effect on the @value{TARGET} family.
521 @ifset DIFF-TBL-KLUGE
522 Issue warnings when difference tables altered for long displacements.
527 Keep (in the symbol table) local symbols. On traditional a.out systems
528 these start with @samp{L}, but different systems have different local
531 @item --listing-lhs-width=@var{number}
532 Set the maximum width, in words, of the output data column for an assembler
533 listing to @var{number}.
535 @item --listing-lhs-width2=@var{number}
536 Set the maximum width, in words, of the output data column for continuation
537 lines in an assembler listing to @var{number}.
539 @item --listing-rhs-width=@var{number}
540 Set the maximum width of an input source line, as displayed in a listing, to
543 @item --listing-cont-lines=@var{number}
544 Set the maximum number of lines printed in a listing for a single line of input
547 @item -o @var{objfile}
548 Name the object-file output from @command{@value{AS}} @var{objfile}.
551 Fold the data section into the text section.
554 Print the maximum space (in bytes) and total time (in seconds) used by
557 @item --strip-local-absolute
558 Remove local absolute symbols from the outgoing symbol table.
562 Print the @command{as} version.
565 Print the @command{as} version and exit.
569 Suppress warning messages.
571 @item --fatal-warnings
572 Treat warnings as errors.
575 Don't suppress warning messages or treat them as errors.
584 Generate an object file even after errors.
586 @item -- | @var{files} @dots{}
587 Standard input, or source files to assemble.
592 The following options are available when @value{AS} is configured for
597 This option selects the core processor variant.
599 Select either big-endian (-EB) or little-endian (-EL) output.
604 The following options are available when @value{AS} is configured for the ARM
608 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
609 Specify which ARM processor variant is the target.
610 @item -march=@var{architecture}[+@var{extension}@dots{}]
611 Specify which ARM architecture variant is used by the target.
612 @item -mfpu=@var{floating-point-format}
613 Select which Floating Point architecture is the target.
614 @item -mfloat-abi=@var{abi}
615 Select which floating point ABI is in use.
617 Enable Thumb only instruction decoding.
618 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
619 Select which procedure calling convention is in use.
621 Select either big-endian (-EB) or little-endian (-EL) output.
622 @item -mthumb-interwork
623 Specify that the code has been generated with interworking between Thumb and
626 Specify that PIC code has been generated.
631 See the info pages for documentation of the CRIS-specific options.
635 The following options are available when @value{AS} is configured for
638 @cindex D10V optimization
639 @cindex optimization, D10V
641 Optimize output by parallelizing instructions.
646 The following options are available when @value{AS} is configured for a D30V
649 @cindex D30V optimization
650 @cindex optimization, D30V
652 Optimize output by parallelizing instructions.
656 Warn when nops are generated.
658 @cindex D30V nops after 32-bit multiply
660 Warn when a nop after a 32-bit multiply instruction is generated.
665 The following options are available when @value{AS} is configured for the
666 Intel 80960 processor.
669 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
670 Specify which variant of the 960 architecture is the target.
673 Add code to collect statistics about branches taken.
676 Do not alter compare-and-branch instructions for long displacements;
683 The following options are available when @value{AS} is configured for the
689 Specifies that the extended IP2022 instructions are allowed.
692 Restores the default behaviour, which restricts the permitted instructions to
693 just the basic IP2022 ones.
699 The following options are available when @value{AS} is configured for the
700 Renesas M32R (formerly Mitsubishi M32R) series.
705 Specify which processor in the M32R family is the target. The default
706 is normally the M32R, but this option changes it to the M32RX.
708 @item --warn-explicit-parallel-conflicts or --Wp
709 Produce warning messages when questionable parallel constructs are
712 @item --no-warn-explicit-parallel-conflicts or --Wnp
713 Do not produce warning messages when questionable parallel constructs are
720 The following options are available when @value{AS} is configured for the
721 Motorola 68000 series.
726 Shorten references to undefined symbols, to one word instead of two.
728 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
729 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
730 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
731 Specify what processor in the 68000 family is the target. The default
732 is normally the 68020, but this can be changed at configuration time.
734 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
735 The target machine does (or does not) have a floating-point coprocessor.
736 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
737 the basic 68000 is not compatible with the 68881, a combination of the
738 two can be specified, since it's possible to do emulation of the
739 coprocessor instructions with the main processor.
741 @item -m68851 | -mno-68851
742 The target machine does (or does not) have a memory-management
743 unit coprocessor. The default is to assume an MMU for 68020 and up.
750 For details about the PDP-11 machine dependent features options,
751 see @ref{PDP-11-Options}.
754 @item -mpic | -mno-pic
755 Generate position-independent (or position-dependent) code. The
756 default is @option{-mpic}.
759 @itemx -mall-extensions
760 Enable all instruction set extensions. This is the default.
762 @item -mno-extensions
763 Disable all instruction set extensions.
765 @item -m@var{extension} | -mno-@var{extension}
766 Enable (or disable) a particular instruction set extension.
769 Enable the instruction set extensions supported by a particular CPU, and
770 disable all other extensions.
772 @item -m@var{machine}
773 Enable the instruction set extensions supported by a particular machine
774 model, and disable all other extensions.
780 The following options are available when @value{AS} is configured for
781 a picoJava processor.
785 @cindex PJ endianness
786 @cindex endianness, PJ
787 @cindex big endian output, PJ
789 Generate ``big endian'' format output.
791 @cindex little endian output, PJ
793 Generate ``little endian'' format output.
799 The following options are available when @value{AS} is configured for the
800 Motorola 68HC11 or 68HC12 series.
804 @item -m68hc11 | -m68hc12 | -m68hcs12
805 Specify what processor is the target. The default is
806 defined by the configuration option when building the assembler.
809 Specify to use the 16-bit integer ABI.
812 Specify to use the 32-bit integer ABI.
815 Specify to use the 32-bit double ABI.
818 Specify to use the 64-bit double ABI.
820 @item --force-long-branchs
821 Relative branches are turned into absolute ones. This concerns
822 conditional branches, unconditional branches and branches to a
825 @item -S | --short-branchs
826 Do not turn relative branchs into absolute ones
827 when the offset is out of range.
829 @item --strict-direct-mode
830 Do not turn the direct addressing mode into extended addressing mode
831 when the instruction does not support direct addressing mode.
833 @item --print-insn-syntax
834 Print the syntax of instruction in case of error.
836 @item --print-opcodes
837 print the list of instructions with syntax and then exit.
839 @item --generate-example
840 print an example of instruction for each possible instruction and then exit.
841 This option is only useful for testing @command{@value{AS}}.
847 The following options are available when @command{@value{AS}} is configured
848 for the SPARC architecture:
851 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
852 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
853 Explicitly select a variant of the SPARC architecture.
855 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
856 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
858 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
859 UltraSPARC extensions.
861 @item -xarch=v8plus | -xarch=v8plusa
862 For compatibility with the Solaris v9 assembler. These options are
863 equivalent to -Av8plus and -Av8plusa, respectively.
866 Warn when the assembler switches to another architecture.
871 The following options are available when @value{AS} is configured for the 'c54x
876 Enable extended addressing mode. All addresses and relocations will assume
877 extended addressing (usually 23 bits).
878 @item -mcpu=@var{CPU_VERSION}
879 Sets the CPU version being compiled for.
880 @item -merrors-to-file @var{FILENAME}
881 Redirect error output to a file, for broken systems which don't support such
882 behaviour in the shell.
887 The following options are available when @value{AS} is configured for
888 a @sc{mips} processor.
892 This option sets the largest size of an object that can be referenced
893 implicitly with the @code{gp} register. It is only accepted for targets that
894 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
896 @cindex MIPS endianness
897 @cindex endianness, MIPS
898 @cindex big endian output, MIPS
900 Generate ``big endian'' format output.
902 @cindex little endian output, MIPS
904 Generate ``little endian'' format output.
916 Generate code for a particular @sc{mips} Instruction Set Architecture level.
917 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
918 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
919 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
920 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and
922 correspond to generic
923 @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64},
924 and @samp{MIPS64 Release 2}
925 ISA processors, respectively.
927 @item -march=@var{CPU}
928 Generate code for a particular @sc{mips} cpu.
930 @item -mtune=@var{cpu}
931 Schedule and tune for a particular @sc{mips} cpu.
935 Cause nops to be inserted if the read of the destination register
936 of an mfhi or mflo instruction occurs in the following two instructions.
940 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
941 section instead of the standard ELF .stabs sections.
945 Control generation of @code{.pdr} sections.
949 The register sizes are normally inferred from the ISA and ABI, but these
950 flags force a certain group of registers to be treated as 32 bits wide at
951 all times. @samp{-mgp32} controls the size of general-purpose registers
952 and @samp{-mfp32} controls the size of floating-point registers.
956 Generate code for the MIPS 16 processor. This is equivalent to putting
957 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
958 turns off this option.
962 Generate code for the MIPS-3D Application Specific Extension.
963 This tells the assembler to accept MIPS-3D instructions.
964 @samp{-no-mips3d} turns off this option.
968 Generate code for the MDMX Application Specific Extension.
969 This tells the assembler to accept MDMX instructions.
970 @samp{-no-mdmx} turns off this option.
972 @item --construct-floats
973 @itemx --no-construct-floats
974 The @samp{--no-construct-floats} option disables the construction of
975 double width floating point constants by loading the two halves of the
976 value into the two single width floating point registers that make up
977 the double width register. By default @samp{--construct-floats} is
978 selected, allowing construction of these floating point constants.
981 @item --emulation=@var{name}
982 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
983 for some other target, in all respects, including output format (choosing
984 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
985 debugging information or store symbol table information, and default
986 endianness. The available configuration names are: @samp{mipsecoff},
987 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
988 @samp{mipsbelf}. The first two do not alter the default endianness from that
989 of the primary target for which the assembler was configured; the others change
990 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
991 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
992 selection in any case.
994 This option is currently supported only when the primary target
995 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
996 Furthermore, the primary target or others specified with
997 @samp{--enable-targets=@dots{}} at configuration time must include support for
998 the other format, if both are to be available. For example, the Irix 5
999 configuration includes support for both.
1001 Eventually, this option will support more configurations, with more
1002 fine-grained control over the assembler's behavior, and will be supported for
1006 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1013 Control how to deal with multiplication overflow and division by zero.
1014 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1015 (and only work for Instruction Set Architecture level 2 and higher);
1016 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1020 When this option is used, @command{@value{AS}} will issue a warning every
1021 time it generates a nop instruction from a macro.
1026 The following options are available when @value{AS} is configured for
1032 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1033 The command line option @samp{-nojsri2bsr} can be used to disable it.
1037 Enable or disable the silicon filter behaviour. By default this is disabled.
1038 The default can be overridden by the @samp{-sifilter} command line option.
1041 Alter jump instructions for long displacements.
1043 @item -mcpu=[210|340]
1044 Select the cpu type on the target hardware. This controls which instructions
1048 Assemble for a big endian target.
1051 Assemble for a little endian target.
1057 See the info pages for documentation of the MMIX-specific options.
1061 The following options are available when @value{AS} is configured for
1062 an Xtensa processor.
1065 @item --text-section-literals | --no-text-section-literals
1066 With @option{--text-@-section-@-literals}, literal pools are interspersed
1067 in the text section. The default is
1068 @option{--no-@-text-@-section-@-literals}, which places literals in a
1069 separate section in the output file. These options only affect literals
1070 referenced via PC-relative @code{L32R} instructions; literals for
1071 absolute mode @code{L32R} instructions are handled separately.
1073 @item --absolute-literals | --no-absolute-literals
1074 Indicate to the assembler whether @code{L32R} instructions use absolute
1075 or PC-relative addressing. The default is to assume absolute addressing
1076 if the Xtensa processor includes the absolute @code{L32R} addressing
1077 option. Otherwise, only the PC-relative @code{L32R} mode can be used.
1079 @item --target-align | --no-target-align
1080 Enable or disable automatic alignment to reduce branch penalties at the
1081 expense of some code density. The default is @option{--target-@-align}.
1083 @item --longcalls | --no-longcalls
1084 Enable or disable transformation of call instructions to allow calls
1085 across a greater range of addresses. The default is
1086 @option{--no-@-longcalls}.
1088 @item --transform | --no-transform
1089 Enable or disable all assembler transformations of Xtensa instructions.
1090 The default is @option{--transform};
1091 @option{--no-transform} should be used only in the rare cases when the
1092 instructions must be exactly as specified in the assembly source.
1099 * Manual:: Structure of this Manual
1100 * GNU Assembler:: The GNU Assembler
1101 * Object Formats:: Object File Formats
1102 * Command Line:: Command Line
1103 * Input Files:: Input Files
1104 * Object:: Output (Object) File
1105 * Errors:: Error and Warning Messages
1109 @section Structure of this Manual
1111 @cindex manual, structure and purpose
1112 This manual is intended to describe what you need to know to use
1113 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1114 notation for symbols, constants, and expressions; the directives that
1115 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1118 We also cover special features in the @value{TARGET}
1119 configuration of @command{@value{AS}}, including assembler directives.
1122 This manual also describes some of the machine-dependent features of
1123 various flavors of the assembler.
1126 @cindex machine instructions (not covered)
1127 On the other hand, this manual is @emph{not} intended as an introduction
1128 to programming in assembly language---let alone programming in general!
1129 In a similar vein, we make no attempt to introduce the machine
1130 architecture; we do @emph{not} describe the instruction set, standard
1131 mnemonics, registers or addressing modes that are standard to a
1132 particular architecture.
1134 You may want to consult the manufacturer's
1135 machine architecture manual for this information.
1139 For information on the H8/300 machine instruction set, see @cite{H8/300
1140 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1141 Programming Manual} (Renesas).
1144 For information on the H8/500 machine instruction set, see @cite{H8/500
1145 Series Programming Manual} (Renesas M21T001).
1148 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1149 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1150 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1151 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1154 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1158 @c I think this is premature---doc@cygnus.com, 17jan1991
1160 Throughout this manual, we assume that you are running @dfn{GNU},
1161 the portable operating system from the @dfn{Free Software
1162 Foundation, Inc.}. This restricts our attention to certain kinds of
1163 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1164 once this assumption is granted examples and definitions need less
1167 @command{@value{AS}} is part of a team of programs that turn a high-level
1168 human-readable series of instructions into a low-level
1169 computer-readable series of instructions. Different versions of
1170 @command{@value{AS}} are used for different kinds of computer.
1173 @c There used to be a section "Terminology" here, which defined
1174 @c "contents", "byte", "word", and "long". Defining "word" to any
1175 @c particular size is confusing when the .word directive may generate 16
1176 @c bits on one machine and 32 bits on another; in general, for the user
1177 @c version of this manual, none of these terms seem essential to define.
1178 @c They were used very little even in the former draft of the manual;
1179 @c this draft makes an effort to avoid them (except in names of
1183 @section The GNU Assembler
1185 @c man begin DESCRIPTION
1187 @sc{gnu} @command{as} is really a family of assemblers.
1189 This manual describes @command{@value{AS}}, a member of that family which is
1190 configured for the @value{TARGET} architectures.
1192 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1193 should find a fairly similar environment when you use it on another
1194 architecture. Each version has much in common with the others,
1195 including object file formats, most assembler directives (often called
1196 @dfn{pseudo-ops}) and assembler syntax.@refill
1198 @cindex purpose of @sc{gnu} assembler
1199 @command{@value{AS}} is primarily intended to assemble the output of the
1200 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1201 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1202 assemble correctly everything that other assemblers for the same
1203 machine would assemble.
1205 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1208 @c This remark should appear in generic version of manual; assumption
1209 @c here is that generic version sets M680x0.
1210 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1211 assembler for the same architecture; for example, we know of several
1212 incompatible versions of 680x0 assembly language syntax.
1217 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1218 program in one pass of the source file. This has a subtle impact on the
1219 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1221 @node Object Formats
1222 @section Object File Formats
1224 @cindex object file format
1225 The @sc{gnu} assembler can be configured to produce several alternative
1226 object file formats. For the most part, this does not affect how you
1227 write assembly language programs; but directives for debugging symbols
1228 are typically different in different file formats. @xref{Symbol
1229 Attributes,,Symbol Attributes}.
1232 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1233 @value{OBJ-NAME} format object files.
1235 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1237 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1238 @code{a.out} or COFF format object files.
1241 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1242 @code{b.out} or COFF format object files.
1245 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1246 SOM or ELF format object files.
1251 @section Command Line
1253 @cindex command line conventions
1255 After the program name @command{@value{AS}}, the command line may contain
1256 options and file names. Options may appear in any order, and may be
1257 before, after, or between file names. The order of file names is
1260 @cindex standard input, as input file
1262 @file{--} (two hyphens) by itself names the standard input file
1263 explicitly, as one of the files for @command{@value{AS}} to assemble.
1265 @cindex options, command line
1266 Except for @samp{--} any command line argument that begins with a
1267 hyphen (@samp{-}) is an option. Each option changes the behavior of
1268 @command{@value{AS}}. No option changes the way another option works. An
1269 option is a @samp{-} followed by one or more letters; the case of
1270 the letter is important. All options are optional.
1272 Some options expect exactly one file name to follow them. The file
1273 name may either immediately follow the option's letter (compatible
1274 with older assemblers) or it may be the next command argument (@sc{gnu}
1275 standard). These two command lines are equivalent:
1278 @value{AS} -o my-object-file.o mumble.s
1279 @value{AS} -omy-object-file.o mumble.s
1283 @section Input Files
1286 @cindex source program
1287 @cindex files, input
1288 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1289 describe the program input to one run of @command{@value{AS}}. The program may
1290 be in one or more files; how the source is partitioned into files
1291 doesn't change the meaning of the source.
1293 @c I added "con" prefix to "catenation" just to prove I can overcome my
1294 @c APL training... doc@cygnus.com
1295 The source program is a concatenation of the text in all the files, in the
1298 @c man begin DESCRIPTION
1299 Each time you run @command{@value{AS}} it assembles exactly one source
1300 program. The source program is made up of one or more files.
1301 (The standard input is also a file.)
1303 You give @command{@value{AS}} a command line that has zero or more input file
1304 names. The input files are read (from left file name to right). A
1305 command line argument (in any position) that has no special meaning
1306 is taken to be an input file name.
1308 If you give @command{@value{AS}} no file names it attempts to read one input file
1309 from the @command{@value{AS}} standard input, which is normally your terminal. You
1310 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1313 Use @samp{--} if you need to explicitly name the standard input file
1314 in your command line.
1316 If the source is empty, @command{@value{AS}} produces a small, empty object
1321 @subheading Filenames and Line-numbers
1323 @cindex input file linenumbers
1324 @cindex line numbers, in input files
1325 There are two ways of locating a line in the input file (or files) and
1326 either may be used in reporting error messages. One way refers to a line
1327 number in a physical file; the other refers to a line number in a
1328 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1330 @dfn{Physical files} are those files named in the command line given
1331 to @command{@value{AS}}.
1333 @dfn{Logical files} are simply names declared explicitly by assembler
1334 directives; they bear no relation to physical files. Logical file names help
1335 error messages reflect the original source file, when @command{@value{AS}} source
1336 is itself synthesized from other files. @command{@value{AS}} understands the
1337 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1338 @ref{File,,@code{.file}}.
1341 @section Output (Object) File
1347 Every time you run @command{@value{AS}} it produces an output file, which is
1348 your assembly language program translated into numbers. This file
1349 is the object file. Its default name is
1357 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1359 You can give it another name by using the @option{-o} option. Conventionally,
1360 object file names end with @file{.o}. The default name is used for historical
1361 reasons: older assemblers were capable of assembling self-contained programs
1362 directly into a runnable program. (For some formats, this isn't currently
1363 possible, but it can be done for the @code{a.out} format.)
1367 The object file is meant for input to the linker @code{@value{LD}}. It contains
1368 assembled program code, information to help @code{@value{LD}} integrate
1369 the assembled program into a runnable file, and (optionally) symbolic
1370 information for the debugger.
1372 @c link above to some info file(s) like the description of a.out.
1373 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1376 @section Error and Warning Messages
1378 @c man begin DESCRIPTION
1380 @cindex error messages
1381 @cindex warning messages
1382 @cindex messages from assembler
1383 @command{@value{AS}} may write warnings and error messages to the standard error
1384 file (usually your terminal). This should not happen when a compiler
1385 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1386 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1387 grave problem that stops the assembly.
1391 @cindex format of warning messages
1392 Warning messages have the format
1395 file_name:@b{NNN}:Warning Message Text
1399 @cindex line numbers, in warnings/errors
1400 (where @b{NNN} is a line number). If a logical file name has been given
1401 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1402 the current input file is used. If a logical line number was given
1404 (@pxref{Line,,@code{.line}})
1408 (@pxref{Line,,@code{.line}})
1411 (@pxref{Ln,,@code{.ln}})
1414 then it is used to calculate the number printed,
1415 otherwise the actual line in the current source file is printed. The
1416 message text is intended to be self explanatory (in the grand Unix
1419 @cindex format of error messages
1420 Error messages have the format
1422 file_name:@b{NNN}:FATAL:Error Message Text
1424 The file name and line number are derived as for warning
1425 messages. The actual message text may be rather less explanatory
1426 because many of them aren't supposed to happen.
1429 @chapter Command-Line Options
1431 @cindex options, all versions of assembler
1432 This chapter describes command-line options available in @emph{all}
1433 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1435 to the @value{TARGET} target.
1438 to particular machine architectures.
1441 @c man begin DESCRIPTION
1443 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
1444 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1445 The assembler arguments must be separated from each other (and the @samp{-Wa})
1446 by commas. For example:
1449 gcc -c -g -O -Wa,-alh,-L file.c
1453 This passes two options to the assembler: @samp{-alh} (emit a listing to
1454 standard output with high-level and assembly source) and @samp{-L} (retain
1455 local symbols in the symbol table).
1457 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1458 command-line options are automatically passed to the assembler by the compiler.
1459 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1460 precisely what options it passes to each compilation pass, including the
1466 * a:: -a[cdhlns] enable listings
1467 * alternate:: --alternate enable alternate macro syntax
1468 * D:: -D for compatibility
1469 * f:: -f to work faster
1470 * I:: -I for .include search path
1471 @ifclear DIFF-TBL-KLUGE
1472 * K:: -K for compatibility
1474 @ifset DIFF-TBL-KLUGE
1475 * K:: -K for difference tables
1478 * L:: -L to retain local labels
1479 * listing:: --listing-XXX to configure listing output
1480 * M:: -M or --mri to assemble in MRI compatibility mode
1481 * MD:: --MD for dependency tracking
1482 * o:: -o to name the object file
1483 * R:: -R to join data and text sections
1484 * statistics:: --statistics to see statistics about assembly
1485 * traditional-format:: --traditional-format for compatible output
1486 * v:: -v to announce version
1487 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1488 * Z:: -Z to make object file even after errors
1492 @section Enable Listings: @option{-a[cdhlns]}
1501 @cindex listings, enabling
1502 @cindex assembly listings, enabling
1504 These options enable listing output from the assembler. By itself,
1505 @samp{-a} requests high-level, assembly, and symbols listing.
1506 You can use other letters to select specific options for the list:
1507 @samp{-ah} requests a high-level language listing,
1508 @samp{-al} requests an output-program assembly listing, and
1509 @samp{-as} requests a symbol table listing.
1510 High-level listings require that a compiler debugging option like
1511 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1514 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1515 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1516 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1517 omitted from the listing.
1519 Use the @samp{-ad} option to omit debugging directives from the
1522 Once you have specified one of these options, you can further control
1523 listing output and its appearance using the directives @code{.list},
1524 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1526 The @samp{-an} option turns off all forms processing.
1527 If you do not request listing output with one of the @samp{-a} options, the
1528 listing-control directives have no effect.
1530 The letters after @samp{-a} may be combined into one option,
1531 @emph{e.g.}, @samp{-aln}.
1533 Note if the assembler source is coming from the standard input (eg because it
1534 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1535 is being used) then the listing will not contain any comments or preprocessor
1536 directives. This is because the listing code buffers input source lines from
1537 stdin only after they have been preprocessed by the assembler. This reduces
1538 memory usage and makes the code more efficient.
1541 @section @option{--alternate}
1544 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
1547 @section @option{-D}
1550 This option has no effect whatsoever, but it is accepted to make it more
1551 likely that scripts written for other assemblers also work with
1552 @command{@value{AS}}.
1555 @section Work Faster: @option{-f}
1558 @cindex trusted compiler
1559 @cindex faster processing (@option{-f})
1560 @samp{-f} should only be used when assembling programs written by a
1561 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1562 and comment preprocessing on
1563 the input file(s) before assembling them. @xref{Preprocessing,
1567 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1568 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1573 @section @code{.include} Search Path: @option{-I} @var{path}
1575 @kindex -I @var{path}
1576 @cindex paths for @code{.include}
1577 @cindex search path for @code{.include}
1578 @cindex @code{include} directive search path
1579 Use this option to add a @var{path} to the list of directories
1580 @command{@value{AS}} searches for files specified in @code{.include}
1581 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1582 many times as necessary to include a variety of paths. The current
1583 working directory is always searched first; after that, @command{@value{AS}}
1584 searches any @samp{-I} directories in the same order as they were
1585 specified (left to right) on the command line.
1588 @section Difference Tables: @option{-K}
1591 @ifclear DIFF-TBL-KLUGE
1592 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1593 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1594 where it can be used to warn when the assembler alters the machine code
1595 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1596 family does not have the addressing limitations that sometimes lead to this
1597 alteration on other platforms.
1600 @ifset DIFF-TBL-KLUGE
1601 @cindex difference tables, warning
1602 @cindex warning for altered difference tables
1603 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1604 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1605 You can use the @samp{-K} option if you want a warning issued when this
1610 @section Include Local Labels: @option{-L}
1613 @cindex local labels, retaining in output
1614 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1615 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1616 debugging, because they are intended for the use of programs (like
1617 compilers) that compose assembler programs, not for your notice.
1618 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1619 normally debug with them.
1621 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1622 in the object file. Usually if you do this you also tell the linker
1623 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1625 By default, a local label is any label beginning with @samp{L}, but each
1626 target is allowed to redefine the local label prefix.
1628 On the HPPA local labels begin with @samp{L$}.
1632 @section Configuring listing output: @option{--listing}
1634 The listing feature of the assembler can be enabled via the command line switch
1635 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1636 hex dump of the corresponding locations in the output object file, and displays
1637 them as a listing file. The format of this listing can be controlled by pseudo
1638 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1639 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1642 @item --listing-lhs-width=@samp{number}
1643 @kindex --listing-lhs-width
1644 @cindex Width of first line disassembly output
1645 Sets the maximum width, in words, of the first line of the hex byte dump. This
1646 dump appears on the left hand side of the listing output.
1648 @item --listing-lhs-width2=@samp{number}
1649 @kindex --listing-lhs-width2
1650 @cindex Width of continuation lines of disassembly output
1651 Sets the maximum width, in words, of any further lines of the hex byte dump for
1652 a given input source line. If this value is not specified, it defaults to being
1653 the same as the value specified for @samp{--listing-lhs-width}. If neither
1654 switch is used the default is to one.
1656 @item --listing-rhs-width=@samp{number}
1657 @kindex --listing-rhs-width
1658 @cindex Width of source line output
1659 Sets the maximum width, in characters, of the source line that is displayed
1660 alongside the hex dump. The default value for this parameter is 100. The
1661 source line is displayed on the right hand side of the listing output.
1663 @item --listing-cont-lines=@samp{number}
1664 @kindex --listing-cont-lines
1665 @cindex Maximum number of continuation lines
1666 Sets the maximum number of continuation lines of hex dump that will be
1667 displayed for a given single line of source input. The default value is 4.
1671 @section Assemble in MRI Compatibility Mode: @option{-M}
1674 @cindex MRI compatibility mode
1675 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1676 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1677 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1678 configured target) assembler from Microtec Research. The exact nature of the
1679 MRI syntax will not be documented here; see the MRI manuals for more
1680 information. Note in particular that the handling of macros and macro
1681 arguments is somewhat different. The purpose of this option is to permit
1682 assembling existing MRI assembler code using @command{@value{AS}}.
1684 The MRI compatibility is not complete. Certain operations of the MRI assembler
1685 depend upon its object file format, and can not be supported using other object
1686 file formats. Supporting these would require enhancing each object file format
1687 individually. These are:
1690 @item global symbols in common section
1692 The m68k MRI assembler supports common sections which are merged by the linker.
1693 Other object file formats do not support this. @command{@value{AS}} handles
1694 common sections by treating them as a single common symbol. It permits local
1695 symbols to be defined within a common section, but it can not support global
1696 symbols, since it has no way to describe them.
1698 @item complex relocations
1700 The MRI assemblers support relocations against a negated section address, and
1701 relocations which combine the start addresses of two or more sections. These
1702 are not support by other object file formats.
1704 @item @code{END} pseudo-op specifying start address
1706 The MRI @code{END} pseudo-op permits the specification of a start address.
1707 This is not supported by other object file formats. The start address may
1708 instead be specified using the @option{-e} option to the linker, or in a linker
1711 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1713 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1714 name to the output file. This is not supported by other object file formats.
1716 @item @code{ORG} pseudo-op
1718 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1719 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1720 which changes the location within the current section. Absolute sections are
1721 not supported by other object file formats. The address of a section may be
1722 assigned within a linker script.
1725 There are some other features of the MRI assembler which are not supported by
1726 @command{@value{AS}}, typically either because they are difficult or because they
1727 seem of little consequence. Some of these may be supported in future releases.
1731 @item EBCDIC strings
1733 EBCDIC strings are not supported.
1735 @item packed binary coded decimal
1737 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1738 and @code{DCB.P} pseudo-ops are not supported.
1740 @item @code{FEQU} pseudo-op
1742 The m68k @code{FEQU} pseudo-op is not supported.
1744 @item @code{NOOBJ} pseudo-op
1746 The m68k @code{NOOBJ} pseudo-op is not supported.
1748 @item @code{OPT} branch control options
1750 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1751 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1752 relaxes all branches, whether forward or backward, to an appropriate size, so
1753 these options serve no purpose.
1755 @item @code{OPT} list control options
1757 The following m68k @code{OPT} list control options are ignored: @code{C},
1758 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1759 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1761 @item other @code{OPT} options
1763 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1764 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1766 @item @code{OPT} @code{D} option is default
1768 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1769 @code{OPT NOD} may be used to turn it off.
1771 @item @code{XREF} pseudo-op.
1773 The m68k @code{XREF} pseudo-op is ignored.
1775 @item @code{.debug} pseudo-op
1777 The i960 @code{.debug} pseudo-op is not supported.
1779 @item @code{.extended} pseudo-op
1781 The i960 @code{.extended} pseudo-op is not supported.
1783 @item @code{.list} pseudo-op.
1785 The various options of the i960 @code{.list} pseudo-op are not supported.
1787 @item @code{.optimize} pseudo-op
1789 The i960 @code{.optimize} pseudo-op is not supported.
1791 @item @code{.output} pseudo-op
1793 The i960 @code{.output} pseudo-op is not supported.
1795 @item @code{.setreal} pseudo-op
1797 The i960 @code{.setreal} pseudo-op is not supported.
1802 @section Dependency Tracking: @option{--MD}
1805 @cindex dependency tracking
1808 @command{@value{AS}} can generate a dependency file for the file it creates. This
1809 file consists of a single rule suitable for @code{make} describing the
1810 dependencies of the main source file.
1812 The rule is written to the file named in its argument.
1814 This feature is used in the automatic updating of makefiles.
1817 @section Name the Object File: @option{-o}
1820 @cindex naming object file
1821 @cindex object file name
1822 There is always one object file output when you run @command{@value{AS}}. By
1823 default it has the name
1826 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1840 You use this option (which takes exactly one filename) to give the
1841 object file a different name.
1843 Whatever the object file is called, @command{@value{AS}} overwrites any
1844 existing file of the same name.
1847 @section Join Data and Text Sections: @option{-R}
1850 @cindex data and text sections, joining
1851 @cindex text and data sections, joining
1852 @cindex joining text and data sections
1853 @cindex merging text and data sections
1854 @option{-R} tells @command{@value{AS}} to write the object file as if all
1855 data-section data lives in the text section. This is only done at
1856 the very last moment: your binary data are the same, but data
1857 section parts are relocated differently. The data section part of
1858 your object file is zero bytes long because all its bytes are
1859 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1861 When you specify @option{-R} it would be possible to generate shorter
1862 address displacements (because we do not have to cross between text and
1863 data section). We refrain from doing this simply for compatibility with
1864 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1867 When @command{@value{AS}} is configured for COFF or ELF output,
1868 this option is only useful if you use sections named @samp{.text} and
1873 @option{-R} is not supported for any of the HPPA targets. Using
1874 @option{-R} generates a warning from @command{@value{AS}}.
1878 @section Display Assembly Statistics: @option{--statistics}
1880 @kindex --statistics
1881 @cindex statistics, about assembly
1882 @cindex time, total for assembly
1883 @cindex space used, maximum for assembly
1884 Use @samp{--statistics} to display two statistics about the resources used by
1885 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1886 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1889 @node traditional-format
1890 @section Compatible Output: @option{--traditional-format}
1892 @kindex --traditional-format
1893 For some targets, the output of @command{@value{AS}} is different in some ways
1894 from the output of some existing assembler. This switch requests
1895 @command{@value{AS}} to use the traditional format instead.
1897 For example, it disables the exception frame optimizations which
1898 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1901 @section Announce Version: @option{-v}
1905 @cindex assembler version
1906 @cindex version of assembler
1907 You can find out what version of as is running by including the
1908 option @samp{-v} (which you can also spell as @samp{-version}) on the
1912 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1914 @command{@value{AS}} should never give a warning or error message when
1915 assembling compiler output. But programs written by people often
1916 cause @command{@value{AS}} to give a warning that a particular assumption was
1917 made. All such warnings are directed to the standard error file.
1921 @cindex suppressing warnings
1922 @cindex warnings, suppressing
1923 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1924 This only affects the warning messages: it does not change any particular of
1925 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1928 @kindex --fatal-warnings
1929 @cindex errors, caused by warnings
1930 @cindex warnings, causing error
1931 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1932 files that generate warnings to be in error.
1935 @cindex warnings, switching on
1936 You can switch these options off again by specifying @option{--warn}, which
1937 causes warnings to be output as usual.
1940 @section Generate Object File in Spite of Errors: @option{-Z}
1941 @cindex object file, after errors
1942 @cindex errors, continuing after
1943 After an error message, @command{@value{AS}} normally produces no output. If for
1944 some reason you are interested in object file output even after
1945 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1946 option. If there are any errors, @command{@value{AS}} continues anyways, and
1947 writes an object file after a final warning message of the form @samp{@var{n}
1948 errors, @var{m} warnings, generating bad object file.}
1953 @cindex machine-independent syntax
1954 @cindex syntax, machine-independent
1955 This chapter describes the machine-independent syntax allowed in a
1956 source file. @command{@value{AS}} syntax is similar to what many other
1957 assemblers use; it is inspired by the BSD 4.2
1962 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1966 * Preprocessing:: Preprocessing
1967 * Whitespace:: Whitespace
1968 * Comments:: Comments
1969 * Symbol Intro:: Symbols
1970 * Statements:: Statements
1971 * Constants:: Constants
1975 @section Preprocessing
1977 @cindex preprocessing
1978 The @command{@value{AS}} internal preprocessor:
1980 @cindex whitespace, removed by preprocessor
1982 adjusts and removes extra whitespace. It leaves one space or tab before
1983 the keywords on a line, and turns any other whitespace on the line into
1986 @cindex comments, removed by preprocessor
1988 removes all comments, replacing them with a single space, or an
1989 appropriate number of newlines.
1991 @cindex constants, converted by preprocessor
1993 converts character constants into the appropriate numeric values.
1996 It does not do macro processing, include file handling, or
1997 anything else you may get from your C compiler's preprocessor. You can
1998 do include file processing with the @code{.include} directive
1999 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2000 to get other ``CPP'' style preprocessing by giving the input file a
2001 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
2002 Output, gcc.info, Using GNU CC}.
2004 Excess whitespace, comments, and character constants
2005 cannot be used in the portions of the input text that are not
2008 @cindex turning preprocessing on and off
2009 @cindex preprocessing, turning on and off
2012 If the first line of an input file is @code{#NO_APP} or if you use the
2013 @samp{-f} option, whitespace and comments are not removed from the input file.
2014 Within an input file, you can ask for whitespace and comment removal in
2015 specific portions of the by putting a line that says @code{#APP} before the
2016 text that may contain whitespace or comments, and putting a line that says
2017 @code{#NO_APP} after this text. This feature is mainly intend to support
2018 @code{asm} statements in compilers whose output is otherwise free of comments
2025 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2026 Whitespace is used to separate symbols, and to make programs neater for
2027 people to read. Unless within character constants
2028 (@pxref{Characters,,Character Constants}), any whitespace means the same
2029 as exactly one space.
2035 There are two ways of rendering comments to @command{@value{AS}}. In both
2036 cases the comment is equivalent to one space.
2038 Anything from @samp{/*} through the next @samp{*/} is a comment.
2039 This means you may not nest these comments.
2043 The only way to include a newline ('\n') in a comment
2044 is to use this sort of comment.
2047 /* This sort of comment does not nest. */
2050 @cindex line comment character
2051 Anything from the @dfn{line comment} character to the next newline
2052 is considered a comment and is ignored. The line comment character is
2054 @samp{;} for the AMD 29K family;
2057 @samp{;} on the ARC;
2060 @samp{@@} on the ARM;
2063 @samp{;} for the H8/300 family;
2066 @samp{!} for the H8/500 family;
2069 @samp{;} for the HPPA;
2072 @samp{#} on the i386 and x86-64;
2075 @samp{#} on the i960;
2078 @samp{;} for the PDP-11;
2081 @samp{;} for picoJava;
2084 @samp{#} for Motorola PowerPC;
2087 @samp{!} for the Renesas / SuperH SH;
2090 @samp{!} on the SPARC;
2093 @samp{#} on the ip2k;
2096 @samp{#} on the m32r;
2099 @samp{|} on the 680x0;
2102 @samp{#} on the 68HC11 and 68HC12;
2105 @samp{;} on the M880x0;
2108 @samp{#} on the Vax;
2111 @samp{!} for the Z8000;
2114 @samp{#} on the V850;
2117 @samp{#} for Xtensa systems;
2119 see @ref{Machine Dependencies}. @refill
2120 @c FIXME What about i860?
2123 On some machines there are two different line comment characters. One
2124 character only begins a comment if it is the first non-whitespace character on
2125 a line, while the other always begins a comment.
2129 The V850 assembler also supports a double dash as starting a comment that
2130 extends to the end of the line.
2136 @cindex lines starting with @code{#}
2137 @cindex logical line numbers
2138 To be compatible with past assemblers, lines that begin with @samp{#} have a
2139 special interpretation. Following the @samp{#} should be an absolute
2140 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2141 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
2142 new logical file name. The rest of the line, if any, should be whitespace.
2144 If the first non-whitespace characters on the line are not numeric,
2145 the line is ignored. (Just like a comment.)
2148 # This is an ordinary comment.
2149 # 42-6 "new_file_name" # New logical file name
2150 # This is logical line # 36.
2152 This feature is deprecated, and may disappear from future versions
2153 of @command{@value{AS}}.
2158 @cindex characters used in symbols
2159 @ifclear SPECIAL-SYMS
2160 A @dfn{symbol} is one or more characters chosen from the set of all
2161 letters (both upper and lower case), digits and the three characters
2167 A @dfn{symbol} is one or more characters chosen from the set of all
2168 letters (both upper and lower case), digits and the three characters
2169 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2175 On most machines, you can also use @code{$} in symbol names; exceptions
2176 are noted in @ref{Machine Dependencies}.
2178 No symbol may begin with a digit. Case is significant.
2179 There is no length limit: all characters are significant. Symbols are
2180 delimited by characters not in that set, or by the beginning of a file
2181 (since the source program must end with a newline, the end of a file is
2182 not a possible symbol delimiter). @xref{Symbols}.
2183 @cindex length of symbols
2188 @cindex statements, structure of
2189 @cindex line separator character
2190 @cindex statement separator character
2192 @ifclear abnormal-separator
2193 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2194 semicolon (@samp{;}). The newline or semicolon is considered part of
2195 the preceding statement. Newlines and semicolons within character
2196 constants are an exception: they do not end statements.
2198 @ifset abnormal-separator
2200 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2201 sign (@samp{@@}). The newline or at sign is considered part of the
2202 preceding statement. Newlines and at signs within character constants
2203 are an exception: they do not end statements.
2206 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2207 point (@samp{!}). The newline or exclamation point is considered part of the
2208 preceding statement. Newlines and exclamation points within character
2209 constants are an exception: they do not end statements.
2212 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2213 H8/300) a dollar sign (@samp{$}); or (for the
2216 (@samp{;}). The newline or separator character is considered part of
2217 the preceding statement. Newlines and separators within character
2218 constants are an exception: they do not end statements.
2223 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2224 separator character. (The line separator is usually @samp{;}, unless
2225 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2226 newline or separator character is considered part of the preceding
2227 statement. Newlines and separators within character constants are an
2228 exception: they do not end statements.
2231 @cindex newline, required at file end
2232 @cindex EOF, newline must precede
2233 It is an error to end any statement with end-of-file: the last
2234 character of any input file should be a newline.@refill
2236 An empty statement is allowed, and may include whitespace. It is ignored.
2238 @cindex instructions and directives
2239 @cindex directives and instructions
2240 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2241 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2243 A statement begins with zero or more labels, optionally followed by a
2244 key symbol which determines what kind of statement it is. The key
2245 symbol determines the syntax of the rest of the statement. If the
2246 symbol begins with a dot @samp{.} then the statement is an assembler
2247 directive: typically valid for any computer. If the symbol begins with
2248 a letter the statement is an assembly language @dfn{instruction}: it
2249 assembles into a machine language instruction.
2251 Different versions of @command{@value{AS}} for different computers
2252 recognize different instructions. In fact, the same symbol may
2253 represent a different instruction in a different computer's assembly
2257 @cindex @code{:} (label)
2258 @cindex label (@code{:})
2259 A label is a symbol immediately followed by a colon (@code{:}).
2260 Whitespace before a label or after a colon is permitted, but you may not
2261 have whitespace between a label's symbol and its colon. @xref{Labels}.
2264 For HPPA targets, labels need not be immediately followed by a colon, but
2265 the definition of a label must begin in column zero. This also implies that
2266 only one label may be defined on each line.
2270 label: .directive followed by something
2271 another_label: # This is an empty statement.
2272 instruction operand_1, operand_2, @dots{}
2279 A constant is a number, written so that its value is known by
2280 inspection, without knowing any context. Like this:
2283 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2284 .ascii "Ring the bell\7" # A string constant.
2285 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2286 .float 0f-314159265358979323846264338327\
2287 95028841971.693993751E-40 # - pi, a flonum.
2292 * Characters:: Character Constants
2293 * Numbers:: Number Constants
2297 @subsection Character Constants
2299 @cindex character constants
2300 @cindex constants, character
2301 There are two kinds of character constants. A @dfn{character} stands
2302 for one character in one byte and its value may be used in
2303 numeric expressions. String constants (properly called string
2304 @emph{literals}) are potentially many bytes and their values may not be
2305 used in arithmetic expressions.
2309 * Chars:: Characters
2313 @subsubsection Strings
2315 @cindex string constants
2316 @cindex constants, string
2317 A @dfn{string} is written between double-quotes. It may contain
2318 double-quotes or null characters. The way to get special characters
2319 into a string is to @dfn{escape} these characters: precede them with
2320 a backslash @samp{\} character. For example @samp{\\} represents
2321 one backslash: the first @code{\} is an escape which tells
2322 @command{@value{AS}} to interpret the second character literally as a backslash
2323 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2324 escape character). The complete list of escapes follows.
2326 @cindex escape codes, character
2327 @cindex character escape codes
2330 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2332 @cindex @code{\b} (backspace character)
2333 @cindex backspace (@code{\b})
2335 Mnemonic for backspace; for ASCII this is octal code 010.
2338 @c Mnemonic for EOText; for ASCII this is octal code 004.
2340 @cindex @code{\f} (formfeed character)
2341 @cindex formfeed (@code{\f})
2343 Mnemonic for FormFeed; for ASCII this is octal code 014.
2345 @cindex @code{\n} (newline character)
2346 @cindex newline (@code{\n})
2348 Mnemonic for newline; for ASCII this is octal code 012.
2351 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2353 @cindex @code{\r} (carriage return character)
2354 @cindex carriage return (@code{\r})
2356 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2359 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2360 @c other assemblers.
2362 @cindex @code{\t} (tab)
2363 @cindex tab (@code{\t})
2365 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2368 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2369 @c @item \x @var{digit} @var{digit} @var{digit}
2370 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2372 @cindex @code{\@var{ddd}} (octal character code)
2373 @cindex octal character code (@code{\@var{ddd}})
2374 @item \ @var{digit} @var{digit} @var{digit}
2375 An octal character code. The numeric code is 3 octal digits.
2376 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2377 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2379 @cindex @code{\@var{xd...}} (hex character code)
2380 @cindex hex character code (@code{\@var{xd...}})
2381 @item \@code{x} @var{hex-digits...}
2382 A hex character code. All trailing hex digits are combined. Either upper or
2383 lower case @code{x} works.
2385 @cindex @code{\\} (@samp{\} character)
2386 @cindex backslash (@code{\\})
2388 Represents one @samp{\} character.
2391 @c Represents one @samp{'} (accent acute) character.
2392 @c This is needed in single character literals
2393 @c (@xref{Characters,,Character Constants}.) to represent
2396 @cindex @code{\"} (doublequote character)
2397 @cindex doublequote (@code{\"})
2399 Represents one @samp{"} character. Needed in strings to represent
2400 this character, because an unescaped @samp{"} would end the string.
2402 @item \ @var{anything-else}
2403 Any other character when escaped by @kbd{\} gives a warning, but
2404 assembles as if the @samp{\} was not present. The idea is that if
2405 you used an escape sequence you clearly didn't want the literal
2406 interpretation of the following character. However @command{@value{AS}} has no
2407 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2408 code and warns you of the fact.
2411 Which characters are escapable, and what those escapes represent,
2412 varies widely among assemblers. The current set is what we think
2413 the BSD 4.2 assembler recognizes, and is a subset of what most C
2414 compilers recognize. If you are in doubt, do not use an escape
2418 @subsubsection Characters
2420 @cindex single character constant
2421 @cindex character, single
2422 @cindex constant, single character
2423 A single character may be written as a single quote immediately
2424 followed by that character. The same escapes apply to characters as
2425 to strings. So if you want to write the character backslash, you
2426 must write @kbd{'\\} where the first @code{\} escapes the second
2427 @code{\}. As you can see, the quote is an acute accent, not a
2428 grave accent. A newline
2430 @ifclear abnormal-separator
2431 (or semicolon @samp{;})
2433 @ifset abnormal-separator
2435 (or at sign @samp{@@})
2438 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2439 Renesas SH or H8/500)
2443 immediately following an acute accent is taken as a literal character
2444 and does not count as the end of a statement. The value of a character
2445 constant in a numeric expression is the machine's byte-wide code for
2446 that character. @command{@value{AS}} assumes your character code is ASCII:
2447 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2450 @subsection Number Constants
2452 @cindex constants, number
2453 @cindex number constants
2454 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2455 are stored in the target machine. @emph{Integers} are numbers that
2456 would fit into an @code{int} in the C language. @emph{Bignums} are
2457 integers, but they are stored in more than 32 bits. @emph{Flonums}
2458 are floating point numbers, described below.
2461 * Integers:: Integers
2466 * Bit Fields:: Bit Fields
2472 @subsubsection Integers
2474 @cindex constants, integer
2476 @cindex binary integers
2477 @cindex integers, binary
2478 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2479 the binary digits @samp{01}.
2481 @cindex octal integers
2482 @cindex integers, octal
2483 An octal integer is @samp{0} followed by zero or more of the octal
2484 digits (@samp{01234567}).
2486 @cindex decimal integers
2487 @cindex integers, decimal
2488 A decimal integer starts with a non-zero digit followed by zero or
2489 more digits (@samp{0123456789}).
2491 @cindex hexadecimal integers
2492 @cindex integers, hexadecimal
2493 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2494 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2496 Integers have the usual values. To denote a negative integer, use
2497 the prefix operator @samp{-} discussed under expressions
2498 (@pxref{Prefix Ops,,Prefix Operators}).
2501 @subsubsection Bignums
2504 @cindex constants, bignum
2505 A @dfn{bignum} has the same syntax and semantics as an integer
2506 except that the number (or its negative) takes more than 32 bits to
2507 represent in binary. The distinction is made because in some places
2508 integers are permitted while bignums are not.
2511 @subsubsection Flonums
2513 @cindex floating point numbers
2514 @cindex constants, floating point
2516 @cindex precision, floating point
2517 A @dfn{flonum} represents a floating point number. The translation is
2518 indirect: a decimal floating point number from the text is converted by
2519 @command{@value{AS}} to a generic binary floating point number of more than
2520 sufficient precision. This generic floating point number is converted
2521 to a particular computer's floating point format (or formats) by a
2522 portion of @command{@value{AS}} specialized to that computer.
2524 A flonum is written by writing (in order)
2529 (@samp{0} is optional on the HPPA.)
2533 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2535 @kbd{e} is recommended. Case is not important.
2537 @c FIXME: verify if flonum syntax really this vague for most cases
2538 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2539 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2542 On the H8/300, H8/500,
2543 Renesas / SuperH SH,
2544 and AMD 29K architectures, the letter must be
2545 one of the letters @samp{DFPRSX} (in upper or lower case).
2547 On the ARC, the letter must be one of the letters @samp{DFRS}
2548 (in upper or lower case).
2550 On the Intel 960 architecture, the letter must be
2551 one of the letters @samp{DFT} (in upper or lower case).
2553 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2557 One of the letters @samp{DFPRSX} (in upper or lower case).
2560 One of the letters @samp{DFRS} (in upper or lower case).
2563 One of the letters @samp{DFPRSX} (in upper or lower case).
2566 The letter @samp{E} (upper case only).
2569 One of the letters @samp{DFT} (in upper or lower case).
2574 An optional sign: either @samp{+} or @samp{-}.
2577 An optional @dfn{integer part}: zero or more decimal digits.
2580 An optional @dfn{fractional part}: @samp{.} followed by zero
2581 or more decimal digits.
2584 An optional exponent, consisting of:
2588 An @samp{E} or @samp{e}.
2589 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2590 @c principle this can perfectly well be different on different targets.
2592 Optional sign: either @samp{+} or @samp{-}.
2594 One or more decimal digits.
2599 At least one of the integer part or the fractional part must be
2600 present. The floating point number has the usual base-10 value.
2602 @command{@value{AS}} does all processing using integers. Flonums are computed
2603 independently of any floating point hardware in the computer running
2604 @command{@value{AS}}.
2608 @c Bit fields are written as a general facility but are also controlled
2609 @c by a conditional-compilation flag---which is as of now (21mar91)
2610 @c turned on only by the i960 config of GAS.
2612 @subsubsection Bit Fields
2615 @cindex constants, bit field
2616 You can also define numeric constants as @dfn{bit fields}.
2617 specify two numbers separated by a colon---
2619 @var{mask}:@var{value}
2622 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2625 The resulting number is then packed
2627 @c this conditional paren in case bit fields turned on elsewhere than 960
2628 (in host-dependent byte order)
2630 into a field whose width depends on which assembler directive has the
2631 bit-field as its argument. Overflow (a result from the bitwise and
2632 requiring more binary digits to represent) is not an error; instead,
2633 more constants are generated, of the specified width, beginning with the
2634 least significant digits.@refill
2636 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2637 @code{.short}, and @code{.word} accept bit-field arguments.
2642 @chapter Sections and Relocation
2647 * Secs Background:: Background
2648 * Ld Sections:: Linker Sections
2649 * As Sections:: Assembler Internal Sections
2650 * Sub-Sections:: Sub-Sections
2654 @node Secs Background
2657 Roughly, a section is a range of addresses, with no gaps; all data
2658 ``in'' those addresses is treated the same for some particular purpose.
2659 For example there may be a ``read only'' section.
2661 @cindex linker, and assembler
2662 @cindex assembler, and linker
2663 The linker @code{@value{LD}} reads many object files (partial programs) and
2664 combines their contents to form a runnable program. When @command{@value{AS}}
2665 emits an object file, the partial program is assumed to start at address 0.
2666 @code{@value{LD}} assigns the final addresses for the partial program, so that
2667 different partial programs do not overlap. This is actually an
2668 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2671 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2672 addresses. These blocks slide to their run-time addresses as rigid
2673 units; their length does not change and neither does the order of bytes
2674 within them. Such a rigid unit is called a @emph{section}. Assigning
2675 run-time addresses to sections is called @dfn{relocation}. It includes
2676 the task of adjusting mentions of object-file addresses so they refer to
2677 the proper run-time addresses.
2679 For the H8/300 and H8/500,
2680 and for the Renesas / SuperH SH,
2681 @command{@value{AS}} pads sections if needed to
2682 ensure they end on a word (sixteen bit) boundary.
2685 @cindex standard assembler sections
2686 An object file written by @command{@value{AS}} has at least three sections, any
2687 of which may be empty. These are named @dfn{text}, @dfn{data} and
2692 When it generates COFF or ELF output,
2694 @command{@value{AS}} can also generate whatever other named sections you specify
2695 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2696 If you do not use any directives that place output in the @samp{.text}
2697 or @samp{.data} sections, these sections still exist, but are empty.
2702 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2704 @command{@value{AS}} can also generate whatever other named sections you
2705 specify using the @samp{.space} and @samp{.subspace} directives. See
2706 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2707 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2708 assembler directives.
2711 Additionally, @command{@value{AS}} uses different names for the standard
2712 text, data, and bss sections when generating SOM output. Program text
2713 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2714 BSS into @samp{$BSS$}.
2718 Within the object file, the text section starts at address @code{0}, the
2719 data section follows, and the bss section follows the data section.
2722 When generating either SOM or ELF output files on the HPPA, the text
2723 section starts at address @code{0}, the data section at address
2724 @code{0x4000000}, and the bss section follows the data section.
2727 To let @code{@value{LD}} know which data changes when the sections are
2728 relocated, and how to change that data, @command{@value{AS}} also writes to the
2729 object file details of the relocation needed. To perform relocation
2730 @code{@value{LD}} must know, each time an address in the object
2734 Where in the object file is the beginning of this reference to
2737 How long (in bytes) is this reference?
2739 Which section does the address refer to? What is the numeric value of
2741 (@var{address}) @minus{} (@var{start-address of section})?
2744 Is the reference to an address ``Program-Counter relative''?
2747 @cindex addresses, format of
2748 @cindex section-relative addressing
2749 In fact, every address @command{@value{AS}} ever uses is expressed as
2751 (@var{section}) + (@var{offset into section})
2754 Further, most expressions @command{@value{AS}} computes have this section-relative
2757 (For some object formats, such as SOM for the HPPA, some expressions are
2758 symbol-relative instead.)
2761 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2762 @var{N} into section @var{secname}.''
2764 Apart from text, data and bss sections you need to know about the
2765 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2766 addresses in the absolute section remain unchanged. For example, address
2767 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2768 @code{@value{LD}}. Although the linker never arranges two partial programs'
2769 data sections with overlapping addresses after linking, @emph{by definition}
2770 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2771 part of a program is always the same address when the program is running as
2772 address @code{@{absolute@ 239@}} in any other part of the program.
2774 The idea of sections is extended to the @dfn{undefined} section. Any
2775 address whose section is unknown at assembly time is by definition
2776 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2777 Since numbers are always defined, the only way to generate an undefined
2778 address is to mention an undefined symbol. A reference to a named
2779 common block would be such a symbol: its value is unknown at assembly
2780 time so it has section @emph{undefined}.
2782 By analogy the word @emph{section} is used to describe groups of sections in
2783 the linked program. @code{@value{LD}} puts all partial programs' text
2784 sections in contiguous addresses in the linked program. It is
2785 customary to refer to the @emph{text section} of a program, meaning all
2786 the addresses of all partial programs' text sections. Likewise for
2787 data and bss sections.
2789 Some sections are manipulated by @code{@value{LD}}; others are invented for
2790 use of @command{@value{AS}} and have no meaning except during assembly.
2793 @section Linker Sections
2794 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2799 @cindex named sections
2800 @cindex sections, named
2801 @item named sections
2804 @cindex text section
2805 @cindex data section
2809 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2810 separate but equal sections. Anything you can say of one section is
2813 When the program is running, however, it is
2814 customary for the text section to be unalterable. The
2815 text section is often shared among processes: it contains
2816 instructions, constants and the like. The data section of a running
2817 program is usually alterable: for example, C variables would be stored
2818 in the data section.
2823 This section contains zeroed bytes when your program begins running. It
2824 is used to hold uninitialized variables or common storage. The length of
2825 each partial program's bss section is important, but because it starts
2826 out containing zeroed bytes there is no need to store explicit zero
2827 bytes in the object file. The bss section was invented to eliminate
2828 those explicit zeros from object files.
2830 @cindex absolute section
2831 @item absolute section
2832 Address 0 of this section is always ``relocated'' to runtime address 0.
2833 This is useful if you want to refer to an address that @code{@value{LD}} must
2834 not change when relocating. In this sense we speak of absolute
2835 addresses being ``unrelocatable'': they do not change during relocation.
2837 @cindex undefined section
2838 @item undefined section
2839 This ``section'' is a catch-all for address references to objects not in
2840 the preceding sections.
2841 @c FIXME: ref to some other doc on obj-file formats could go here.
2844 @cindex relocation example
2845 An idealized example of three relocatable sections follows.
2847 The example uses the traditional section names @samp{.text} and @samp{.data}.
2849 Memory addresses are on the horizontal axis.
2853 @c END TEXI2ROFF-KILL
2856 partial program # 1: |ttttt|dddd|00|
2863 partial program # 2: |TTT|DDD|000|
2866 +--+---+-----+--+----+---+-----+~~
2867 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2868 +--+---+-----+--+----+---+-----+~~
2870 addresses: 0 @dots{}
2877 \line{\it Partial program \#1: \hfil}
2878 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2879 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2881 \line{\it Partial program \#2: \hfil}
2882 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2883 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2885 \line{\it linked program: \hfil}
2886 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2887 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2888 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2889 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2891 \line{\it addresses: \hfil}
2895 @c END TEXI2ROFF-KILL
2898 @section Assembler Internal Sections
2900 @cindex internal assembler sections
2901 @cindex sections in messages, internal
2902 These sections are meant only for the internal use of @command{@value{AS}}. They
2903 have no meaning at run-time. You do not really need to know about these
2904 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2905 warning messages, so it might be helpful to have an idea of their
2906 meanings to @command{@value{AS}}. These sections are used to permit the
2907 value of every expression in your assembly language program to be a
2908 section-relative address.
2911 @cindex assembler internal logic error
2912 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2913 An internal assembler logic error has been found. This means there is a
2914 bug in the assembler.
2916 @cindex expr (internal section)
2918 The assembler stores complex expression internally as combinations of
2919 symbols. When it needs to represent an expression as a symbol, it puts
2920 it in the expr section.
2922 @c FIXME item transfer[t] vector preload
2923 @c FIXME item transfer[t] vector postload
2924 @c FIXME item register
2928 @section Sub-Sections
2930 @cindex numbered subsections
2931 @cindex grouping data
2937 fall into two sections: text and data.
2939 You may have separate groups of
2941 data in named sections
2945 data in named sections
2951 that you want to end up near to each other in the object file, even though they
2952 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2953 use @dfn{subsections} for this purpose. Within each section, there can be
2954 numbered subsections with values from 0 to 8192. Objects assembled into the
2955 same subsection go into the object file together with other objects in the same
2956 subsection. For example, a compiler might want to store constants in the text
2957 section, but might not want to have them interspersed with the program being
2958 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2959 section of code being output, and a @samp{.text 1} before each group of
2960 constants being output.
2962 Subsections are optional. If you do not use subsections, everything
2963 goes in subsection number zero.
2966 Each subsection is zero-padded up to a multiple of four bytes.
2967 (Subsections may be padded a different amount on different flavors
2968 of @command{@value{AS}}.)
2972 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2973 boundary (two bytes).
2974 The same is true on the Renesas SH.
2977 @c FIXME section padding (alignment)?
2978 @c Rich Pixley says padding here depends on target obj code format; that
2979 @c doesn't seem particularly useful to say without further elaboration,
2980 @c so for now I say nothing about it. If this is a generic BFD issue,
2981 @c these paragraphs might need to vanish from this manual, and be
2982 @c discussed in BFD chapter of binutils (or some such).
2985 On the AMD 29K family, no particular padding is added to section or
2986 subsection sizes; @value{AS} forces no alignment on this platform.
2990 Subsections appear in your object file in numeric order, lowest numbered
2991 to highest. (All this to be compatible with other people's assemblers.)
2992 The object file contains no representation of subsections; @code{@value{LD}} and
2993 other programs that manipulate object files see no trace of them.
2994 They just see all your text subsections as a text section, and all your
2995 data subsections as a data section.
2997 To specify which subsection you want subsequent statements assembled
2998 into, use a numeric argument to specify it, in a @samp{.text
2999 @var{expression}} or a @samp{.data @var{expression}} statement.
3002 When generating COFF output, you
3007 can also use an extra subsection
3008 argument with arbitrary named sections: @samp{.section @var{name},
3013 When generating ELF output, you
3018 can also use the @code{.subsection} directive (@pxref{SubSection})
3019 to specify a subsection: @samp{.subsection @var{expression}}.
3021 @var{Expression} should be an absolute expression.
3022 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
3023 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3024 begins in @code{text 0}. For instance:
3026 .text 0 # The default subsection is text 0 anyway.
3027 .ascii "This lives in the first text subsection. *"
3029 .ascii "But this lives in the second text subsection."
3031 .ascii "This lives in the data section,"
3032 .ascii "in the first data subsection."
3034 .ascii "This lives in the first text section,"
3035 .ascii "immediately following the asterisk (*)."
3038 Each section has a @dfn{location counter} incremented by one for every byte
3039 assembled into that section. Because subsections are merely a convenience
3040 restricted to @command{@value{AS}} there is no concept of a subsection location
3041 counter. There is no way to directly manipulate a location counter---but the
3042 @code{.align} directive changes it, and any label definition captures its
3043 current value. The location counter of the section where statements are being
3044 assembled is said to be the @dfn{active} location counter.
3047 @section bss Section
3050 @cindex common variable storage
3051 The bss section is used for local common variable storage.
3052 You may allocate address space in the bss section, but you may
3053 not dictate data to load into it before your program executes. When
3054 your program starts running, all the contents of the bss
3055 section are zeroed bytes.
3057 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3058 @ref{Lcomm,,@code{.lcomm}}.
3060 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3061 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
3064 When assembling for a target which supports multiple sections, such as ELF or
3065 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3066 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3067 section. Typically the section will only contain symbol definitions and
3068 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3075 Symbols are a central concept: the programmer uses symbols to name
3076 things, the linker uses symbols to link, and the debugger uses symbols
3080 @cindex debuggers, and symbol order
3081 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3082 the same order they were declared. This may break some debuggers.
3087 * Setting Symbols:: Giving Symbols Other Values
3088 * Symbol Names:: Symbol Names
3089 * Dot:: The Special Dot Symbol
3090 * Symbol Attributes:: Symbol Attributes
3097 A @dfn{label} is written as a symbol immediately followed by a colon
3098 @samp{:}. The symbol then represents the current value of the
3099 active location counter, and is, for example, a suitable instruction
3100 operand. You are warned if you use the same symbol to represent two
3101 different locations: the first definition overrides any other
3105 On the HPPA, the usual form for a label need not be immediately followed by a
3106 colon, but instead must start in column zero. Only one label may be defined on
3107 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3108 provides a special directive @code{.label} for defining labels more flexibly.
3111 @node Setting Symbols
3112 @section Giving Symbols Other Values
3114 @cindex assigning values to symbols
3115 @cindex symbol values, assigning
3116 A symbol can be given an arbitrary value by writing a symbol, followed
3117 by an equals sign @samp{=}, followed by an expression
3118 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3119 directive. @xref{Set,,@code{.set}}.
3122 @section Symbol Names
3124 @cindex symbol names
3125 @cindex names, symbol
3126 @ifclear SPECIAL-SYMS
3127 Symbol names begin with a letter or with one of @samp{._}. On most
3128 machines, you can also use @code{$} in symbol names; exceptions are
3129 noted in @ref{Machine Dependencies}. That character may be followed by any
3130 string of digits, letters, dollar signs (unless otherwise noted in
3131 @ref{Machine Dependencies}), and underscores.
3134 For the AMD 29K family, @samp{?} is also allowed in the
3135 body of a symbol name, though not at its beginning.
3140 Symbol names begin with a letter or with one of @samp{._}. On the
3141 Renesas SH or the H8/500, you can also use @code{$} in symbol names. That
3142 character may be followed by any string of digits, letters, dollar signs (save
3143 on the H8/300), and underscores.
3147 Case of letters is significant: @code{foo} is a different symbol name
3150 Each symbol has exactly one name. Each name in an assembly language program
3151 refers to exactly one symbol. You may use that symbol name any number of times
3154 @subheading Local Symbol Names
3156 @cindex local symbol names
3157 @cindex symbol names, local
3158 @cindex temporary symbol names
3159 @cindex symbol names, temporary
3160 Local symbols help compilers and programmers use names temporarily.
3161 They create symbols which are guaranteed to be unique over the entire scope of
3162 the input source code and which can be referred to by a simple notation.
3163 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3164 represents any positive integer). To refer to the most recent previous
3165 definition of that symbol write @samp{@b{N}b}, using the same number as when
3166 you defined the label. To refer to the next definition of a local label, write
3167 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3170 There is no restriction on how you can use these labels, and you can reuse them
3171 too. So that it is possible to repeatedly define the same local label (using
3172 the same number @samp{@b{N}}), although you can only refer to the most recently
3173 defined local label of that number (for a backwards reference) or the next
3174 definition of a specific local label for a forward reference. It is also worth
3175 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3176 implemented in a slightly more efficient manner than the others.
3187 Which is the equivalent of:
3190 label_1: branch label_3
3191 label_2: branch label_1
3192 label_3: branch label_4
3193 label_4: branch label_3
3196 Local symbol names are only a notational device. They are immediately
3197 transformed into more conventional symbol names before the assembler uses them.
3198 The symbol names stored in the symbol table, appearing in error messages and
3199 optionally emitted to the object file. The names are constructed using these
3204 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3205 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3206 used for symbols you are never intended to see. If you use the
3207 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3208 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3209 you may use them in debugging.
3212 This is the number that was used in the local label definition. So if the
3213 label is written @samp{55:} then the number is @samp{55}.
3216 This unusual character is included so you do not accidentally invent a symbol
3217 of the same name. The character has ASCII value of @samp{\002} (control-B).
3219 @item @emph{ordinal number}
3220 This is a serial number to keep the labels distinct. The first definition of
3221 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3222 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3223 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3226 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3227 @code{3:} is named @code{L3@kbd{C-B}44}.
3229 @subheading Dollar Local Labels
3230 @cindex dollar local symbols
3232 @code{@value{AS}} also supports an even more local form of local labels called
3233 dollar labels. These labels go out of scope (ie they become undefined) as soon
3234 as a non-local label is defined. Thus they remain valid for only a small
3235 region of the input source code. Normal local labels, by contrast, remain in
3236 scope for the entire file, or until they are redefined by another occurrence of
3237 the same local label.
3239 Dollar labels are defined in exactly the same way as ordinary local labels,
3240 except that instead of being terminated by a colon, they are terminated by a
3241 dollar sign. eg @samp{@b{55$}}.
3243 They can also be distinguished from ordinary local labels by their transformed
3244 name which uses ASCII character @samp{\001} (control-A) as the magic character
3245 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3246 is named @samp{L6@kbd{C-A}5}.
3249 @section The Special Dot Symbol
3251 @cindex dot (symbol)
3252 @cindex @code{.} (symbol)
3253 @cindex current address
3254 @cindex location counter
3255 The special symbol @samp{.} refers to the current address that
3256 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3257 .long .} defines @code{melvin} to contain its own address.
3258 Assigning a value to @code{.} is treated the same as a @code{.org}
3259 directive. Thus, the expression @samp{.=.+4} is the same as saying
3260 @ifclear no-space-dir
3269 @node Symbol Attributes
3270 @section Symbol Attributes
3272 @cindex symbol attributes
3273 @cindex attributes, symbol
3274 Every symbol has, as well as its name, the attributes ``Value'' and
3275 ``Type''. Depending on output format, symbols can also have auxiliary
3278 The detailed definitions are in @file{a.out.h}.
3281 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3282 all these attributes, and probably won't warn you. This makes the
3283 symbol an externally defined symbol, which is generally what you
3287 * Symbol Value:: Value
3288 * Symbol Type:: Type
3291 * a.out Symbols:: Symbol Attributes: @code{a.out}
3295 * a.out Symbols:: Symbol Attributes: @code{a.out}
3298 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3303 * COFF Symbols:: Symbol Attributes for COFF
3306 * SOM Symbols:: Symbol Attributes for SOM
3313 @cindex value of a symbol
3314 @cindex symbol value
3315 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3316 location in the text, data, bss or absolute sections the value is the
3317 number of addresses from the start of that section to the label.
3318 Naturally for text, data and bss sections the value of a symbol changes
3319 as @code{@value{LD}} changes section base addresses during linking. Absolute
3320 symbols' values do not change during linking: that is why they are
3323 The value of an undefined symbol is treated in a special way. If it is
3324 0 then the symbol is not defined in this assembler source file, and
3325 @code{@value{LD}} tries to determine its value from other files linked into the
3326 same program. You make this kind of symbol simply by mentioning a symbol
3327 name without defining it. A non-zero value represents a @code{.comm}
3328 common declaration. The value is how much common storage to reserve, in
3329 bytes (addresses). The symbol refers to the first address of the
3335 @cindex type of a symbol
3337 The type attribute of a symbol contains relocation (section)
3338 information, any flag settings indicating that a symbol is external, and
3339 (optionally), other information for linkers and debuggers. The exact
3340 format depends on the object-code output format in use.
3345 @c The following avoids a "widow" subsection title. @group would be
3346 @c better if it were available outside examples.
3349 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3351 @cindex @code{b.out} symbol attributes
3352 @cindex symbol attributes, @code{b.out}
3353 These symbol attributes appear only when @command{@value{AS}} is configured for
3354 one of the Berkeley-descended object output formats---@code{a.out} or
3360 @subsection Symbol Attributes: @code{a.out}
3362 @cindex @code{a.out} symbol attributes
3363 @cindex symbol attributes, @code{a.out}
3369 @subsection Symbol Attributes: @code{a.out}
3371 @cindex @code{a.out} symbol attributes
3372 @cindex symbol attributes, @code{a.out}
3376 * Symbol Desc:: Descriptor
3377 * Symbol Other:: Other
3381 @subsubsection Descriptor
3383 @cindex descriptor, of @code{a.out} symbol
3384 This is an arbitrary 16-bit value. You may establish a symbol's
3385 descriptor value by using a @code{.desc} statement
3386 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3387 @command{@value{AS}}.
3390 @subsubsection Other
3392 @cindex other attribute, of @code{a.out} symbol
3393 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3398 @subsection Symbol Attributes for COFF
3400 @cindex COFF symbol attributes
3401 @cindex symbol attributes, COFF
3403 The COFF format supports a multitude of auxiliary symbol attributes;
3404 like the primary symbol attributes, they are set between @code{.def} and
3405 @code{.endef} directives.
3407 @subsubsection Primary Attributes
3409 @cindex primary attributes, COFF symbols
3410 The symbol name is set with @code{.def}; the value and type,
3411 respectively, with @code{.val} and @code{.type}.
3413 @subsubsection Auxiliary Attributes
3415 @cindex auxiliary attributes, COFF symbols
3416 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3417 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3418 table information for COFF.
3423 @subsection Symbol Attributes for SOM
3425 @cindex SOM symbol attributes
3426 @cindex symbol attributes, SOM
3428 The SOM format for the HPPA supports a multitude of symbol attributes set with
3429 the @code{.EXPORT} and @code{.IMPORT} directives.
3431 The attributes are described in @cite{HP9000 Series 800 Assembly
3432 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3433 @code{EXPORT} assembler directive documentation.
3437 @chapter Expressions
3441 @cindex numeric values
3442 An @dfn{expression} specifies an address or numeric value.
3443 Whitespace may precede and/or follow an expression.
3445 The result of an expression must be an absolute number, or else an offset into
3446 a particular section. If an expression is not absolute, and there is not
3447 enough information when @command{@value{AS}} sees the expression to know its
3448 section, a second pass over the source program might be necessary to interpret
3449 the expression---but the second pass is currently not implemented.
3450 @command{@value{AS}} aborts with an error message in this situation.
3453 * Empty Exprs:: Empty Expressions
3454 * Integer Exprs:: Integer Expressions
3458 @section Empty Expressions
3460 @cindex empty expressions
3461 @cindex expressions, empty
3462 An empty expression has no value: it is just whitespace or null.
3463 Wherever an absolute expression is required, you may omit the
3464 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3465 is compatible with other assemblers.
3468 @section Integer Expressions
3470 @cindex integer expressions
3471 @cindex expressions, integer
3472 An @dfn{integer expression} is one or more @emph{arguments} delimited
3473 by @emph{operators}.
3476 * Arguments:: Arguments
3477 * Operators:: Operators
3478 * Prefix Ops:: Prefix Operators
3479 * Infix Ops:: Infix Operators
3483 @subsection Arguments
3485 @cindex expression arguments
3486 @cindex arguments in expressions
3487 @cindex operands in expressions
3488 @cindex arithmetic operands
3489 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3490 contexts arguments are sometimes called ``arithmetic operands''. In
3491 this manual, to avoid confusing them with the ``instruction operands'' of
3492 the machine language, we use the term ``argument'' to refer to parts of
3493 expressions only, reserving the word ``operand'' to refer only to machine
3494 instruction operands.
3496 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3497 @var{section} is one of text, data, bss, absolute,
3498 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3501 Numbers are usually integers.
3503 A number can be a flonum or bignum. In this case, you are warned
3504 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3505 these 32 bits are an integer. You may write integer-manipulating
3506 instructions that act on exotic constants, compatible with other
3509 @cindex subexpressions
3510 Subexpressions are a left parenthesis @samp{(} followed by an integer
3511 expression, followed by a right parenthesis @samp{)}; or a prefix
3512 operator followed by an argument.
3515 @subsection Operators
3517 @cindex operators, in expressions
3518 @cindex arithmetic functions
3519 @cindex functions, in expressions
3520 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3521 operators are followed by an argument. Infix operators appear
3522 between their arguments. Operators may be preceded and/or followed by
3526 @subsection Prefix Operator
3528 @cindex prefix operators
3529 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3530 one argument, which must be absolute.
3532 @c the tex/end tex stuff surrounding this small table is meant to make
3533 @c it align, on the printed page, with the similar table in the next
3534 @c section (which is inside an enumerate).
3536 \global\advance\leftskip by \itemindent
3541 @dfn{Negation}. Two's complement negation.
3543 @dfn{Complementation}. Bitwise not.
3547 \global\advance\leftskip by -\itemindent
3551 @subsection Infix Operators
3553 @cindex infix operators
3554 @cindex operators, permitted arguments
3555 @dfn{Infix operators} take two arguments, one on either side. Operators
3556 have precedence, but operations with equal precedence are performed left
3557 to right. Apart from @code{+} or @option{-}, both arguments must be
3558 absolute, and the result is absolute.
3561 @cindex operator precedence
3562 @cindex precedence of operators
3569 @dfn{Multiplication}.
3572 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3579 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3583 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3587 Intermediate precedence
3592 @dfn{Bitwise Inclusive Or}.
3598 @dfn{Bitwise Exclusive Or}.
3601 @dfn{Bitwise Or Not}.
3608 @cindex addition, permitted arguments
3609 @cindex plus, permitted arguments
3610 @cindex arguments for addition
3612 @dfn{Addition}. If either argument is absolute, the result has the section of
3613 the other argument. You may not add together arguments from different
3616 @cindex subtraction, permitted arguments
3617 @cindex minus, permitted arguments
3618 @cindex arguments for subtraction
3620 @dfn{Subtraction}. If the right argument is absolute, the
3621 result has the section of the left argument.
3622 If both arguments are in the same section, the result is absolute.
3623 You may not subtract arguments from different sections.
3624 @c FIXME is there still something useful to say about undefined - undefined ?
3626 @cindex comparison expressions
3627 @cindex expressions, comparison
3631 @dfn{Is Not Equal To}
3635 @dfn{Is Greater Than}
3637 @dfn{Is Greater Than Or Equal To}
3639 @dfn{Is Less Than Or Equal To}
3641 The comparison operators can be used as infix operators. A true results has a
3642 value of -1 whereas a false result has a value of 0. Note, these operators
3643 perform signed comparisons.
3646 @item Lowest Precedence
3655 These two logical operations can be used to combine the results of sub
3656 expressions. Note, unlike the comparison operators a true result returns a
3657 value of 1 but a false results does still return 0. Also note that the logical
3658 or operator has a slightly lower precedence than logical and.
3663 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3664 address; you can only have a defined section in one of the two arguments.
3667 @chapter Assembler Directives
3669 @cindex directives, machine independent
3670 @cindex pseudo-ops, machine independent
3671 @cindex machine independent directives
3672 All assembler directives have names that begin with a period (@samp{.}).
3673 The rest of the name is letters, usually in lower case.
3675 This chapter discusses directives that are available regardless of the
3676 target machine configuration for the @sc{gnu} assembler.
3678 Some machine configurations provide additional directives.
3679 @xref{Machine Dependencies}.
3682 @ifset machine-directives
3683 @xref{Machine Dependencies} for additional directives.
3688 * Abort:: @code{.abort}
3690 * ABORT:: @code{.ABORT}
3693 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3694 * Altmacro:: @code{.altmacro}
3695 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3696 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3697 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3698 * Byte:: @code{.byte @var{expressions}}
3699 * Comm:: @code{.comm @var{symbol} , @var{length} }
3701 * CFI directives:: @code{.cfi_startproc}, @code{.cfi_endproc}, etc.
3703 * Data:: @code{.data @var{subsection}}
3705 * Def:: @code{.def @var{name}}
3708 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3714 * Double:: @code{.double @var{flonums}}
3715 * Eject:: @code{.eject}
3716 * Else:: @code{.else}
3717 * Elseif:: @code{.elseif}
3720 * Endef:: @code{.endef}
3723 * Endfunc:: @code{.endfunc}
3724 * Endif:: @code{.endif}
3725 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3726 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3728 * Exitm:: @code{.exitm}
3729 * Extern:: @code{.extern}
3730 * Fail:: @code{.fail}
3731 @ifclear no-file-dir
3732 * File:: @code{.file @var{string}}
3735 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3736 * Float:: @code{.float @var{flonums}}
3737 * Func:: @code{.func}
3738 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3740 * Hidden:: @code{.hidden @var{names}}
3743 * hword:: @code{.hword @var{expressions}}
3744 * Ident:: @code{.ident}
3745 * If:: @code{.if @var{absolute expression}}
3746 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3747 * Include:: @code{.include "@var{file}"}
3748 * Int:: @code{.int @var{expressions}}
3750 * Internal:: @code{.internal @var{names}}
3753 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3754 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3755 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3756 * Lflags:: @code{.lflags}
3757 @ifclear no-line-dir
3758 * Line:: @code{.line @var{line-number}}
3761 * Ln:: @code{.ln @var{line-number}}
3762 * Linkonce:: @code{.linkonce [@var{type}]}
3763 * List:: @code{.list}
3764 * Long:: @code{.long @var{expressions}}
3766 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3769 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3770 * MRI:: @code{.mri @var{val}}
3771 * Noaltmacro:: @code{.noaltmacro}
3772 * Nolist:: @code{.nolist}
3773 * Octa:: @code{.octa @var{bignums}}
3774 * Org:: @code{.org @var{new-lc} , @var{fill}}
3775 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3777 * PopSection:: @code{.popsection}
3778 * Previous:: @code{.previous}
3781 * Print:: @code{.print @var{string}}
3783 * Protected:: @code{.protected @var{names}}
3786 * Psize:: @code{.psize @var{lines}, @var{columns}}
3787 * Purgem:: @code{.purgem @var{name}}
3789 * PushSection:: @code{.pushsection @var{name}}
3792 * Quad:: @code{.quad @var{bignums}}
3793 * Rept:: @code{.rept @var{count}}
3794 * Sbttl:: @code{.sbttl "@var{subheading}"}
3796 * Scl:: @code{.scl @var{class}}
3799 * Section:: @code{.section @var{name}}
3802 * Set:: @code{.set @var{symbol}, @var{expression}}
3803 * Short:: @code{.short @var{expressions}}
3804 * Single:: @code{.single @var{flonums}}
3806 * Size:: @code{.size [@var{name} , @var{expression}]}
3809 * Skip:: @code{.skip @var{size} , @var{fill}}
3810 * Sleb128:: @code{.sleb128 @var{expressions}}
3811 * Space:: @code{.space @var{size} , @var{fill}}
3813 * Stab:: @code{.stabd, .stabn, .stabs}
3816 * String:: @code{.string "@var{str}"}
3817 * Struct:: @code{.struct @var{expression}}
3819 * SubSection:: @code{.subsection}
3820 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3824 * Tag:: @code{.tag @var{structname}}
3827 * Text:: @code{.text @var{subsection}}
3828 * Title:: @code{.title "@var{heading}"}
3830 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3833 * Uleb128:: @code{.uleb128 @var{expressions}}
3835 * Val:: @code{.val @var{addr}}
3839 * Version:: @code{.version "@var{string}"}
3840 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3841 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3844 * Weak:: @code{.weak @var{names}}
3845 * Word:: @code{.word @var{expressions}}
3846 * Deprecated:: Deprecated Directives
3850 @section @code{.abort}
3852 @cindex @code{abort} directive
3853 @cindex stopping the assembly
3854 This directive stops the assembly immediately. It is for
3855 compatibility with other assemblers. The original idea was that the
3856 assembly language source would be piped into the assembler. If the sender
3857 of the source quit, it could use this directive tells @command{@value{AS}} to
3858 quit also. One day @code{.abort} will not be supported.
3862 @section @code{.ABORT}
3864 @cindex @code{ABORT} directive
3865 When producing COFF output, @command{@value{AS}} accepts this directive as a
3866 synonym for @samp{.abort}.
3869 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3875 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3877 @cindex padding the location counter
3878 @cindex @code{align} directive
3879 Pad the location counter (in the current subsection) to a particular storage
3880 boundary. The first expression (which must be absolute) is the alignment
3881 required, as described below.
3883 The second expression (also absolute) gives the fill value to be stored in the
3884 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3885 padding bytes are normally zero. However, on some systems, if the section is
3886 marked as containing code and the fill value is omitted, the space is filled
3887 with no-op instructions.
3889 The third expression is also absolute, and is also optional. If it is present,
3890 it is the maximum number of bytes that should be skipped by this alignment
3891 directive. If doing the alignment would require skipping more bytes than the
3892 specified maximum, then the alignment is not done at all. You can omit the
3893 fill value (the second argument) entirely by simply using two commas after the
3894 required alignment; this can be useful if you want the alignment to be filled
3895 with no-op instructions when appropriate.
3897 The way the required alignment is specified varies from system to system.
3898 For the a29k, arc, hppa, i386 using ELF, i860, iq2000, m68k, m88k, or32,
3899 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
3900 alignment request in bytes. For example @samp{.align 8} advances
3901 the location counter until it is a multiple of 8. If the location counter
3902 is already a multiple of 8, no change is needed. For the tic54x, the
3903 first expression is the alignment request in words.
3905 For other systems, including the i386 using a.out format, and the arm and
3906 strongarm, it is the
3907 number of low-order zero bits the location counter must have after
3908 advancement. For example @samp{.align 3} advances the location
3909 counter until it a multiple of 8. If the location counter is already a
3910 multiple of 8, no change is needed.
3912 This inconsistency is due to the different behaviors of the various
3913 native assemblers for these systems which GAS must emulate.
3914 GAS also provides @code{.balign} and @code{.p2align} directives,
3915 described later, which have a consistent behavior across all
3916 architectures (but are specific to GAS).
3919 @section @code{.ascii "@var{string}"}@dots{}
3921 @cindex @code{ascii} directive
3922 @cindex string literals
3923 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3924 separated by commas. It assembles each string (with no automatic
3925 trailing zero byte) into consecutive addresses.
3928 @section @code{.asciz "@var{string}"}@dots{}
3930 @cindex @code{asciz} directive
3931 @cindex zero-terminated strings
3932 @cindex null-terminated strings
3933 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3934 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3937 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3939 @cindex padding the location counter given number of bytes
3940 @cindex @code{balign} directive
3941 Pad the location counter (in the current subsection) to a particular
3942 storage boundary. The first expression (which must be absolute) is the
3943 alignment request in bytes. For example @samp{.balign 8} advances
3944 the location counter until it is a multiple of 8. If the location counter
3945 is already a multiple of 8, no change is needed.
3947 The second expression (also absolute) gives the fill value to be stored in the
3948 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3949 padding bytes are normally zero. However, on some systems, if the section is
3950 marked as containing code and the fill value is omitted, the space is filled
3951 with no-op instructions.
3953 The third expression is also absolute, and is also optional. If it is present,
3954 it is the maximum number of bytes that should be skipped by this alignment
3955 directive. If doing the alignment would require skipping more bytes than the
3956 specified maximum, then the alignment is not done at all. You can omit the
3957 fill value (the second argument) entirely by simply using two commas after the
3958 required alignment; this can be useful if you want the alignment to be filled
3959 with no-op instructions when appropriate.
3961 @cindex @code{balignw} directive
3962 @cindex @code{balignl} directive
3963 The @code{.balignw} and @code{.balignl} directives are variants of the
3964 @code{.balign} directive. The @code{.balignw} directive treats the fill
3965 pattern as a two byte word value. The @code{.balignl} directives treats the
3966 fill pattern as a four byte longword value. For example, @code{.balignw
3967 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3968 filled in with the value 0x368d (the exact placement of the bytes depends upon
3969 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3973 @section @code{.byte @var{expressions}}
3975 @cindex @code{byte} directive
3976 @cindex integers, one byte
3977 @code{.byte} expects zero or more expressions, separated by commas.
3978 Each expression is assembled into the next byte.
3981 @section @code{.comm @var{symbol} , @var{length} }
3983 @cindex @code{comm} directive
3984 @cindex symbol, common
3985 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3986 common symbol in one object file may be merged with a defined or common symbol
3987 of the same name in another object file. If @code{@value{LD}} does not see a
3988 definition for the symbol--just one or more common symbols--then it will
3989 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3990 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3991 the same name, and they do not all have the same size, it will allocate space
3992 using the largest size.
3995 When using ELF, the @code{.comm} directive takes an optional third argument.
3996 This is the desired alignment of the symbol, specified as a byte boundary (for
3997 example, an alignment of 16 means that the least significant 4 bits of the
3998 address should be zero). The alignment must be an absolute expression, and it
3999 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
4000 for the common symbol, it will use the alignment when placing the symbol. If
4001 no alignment is specified, @command{@value{AS}} will set the alignment to the
4002 largest power of two less than or equal to the size of the symbol, up to a
4007 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4008 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4011 @node CFI directives
4012 @section @code{.cfi_startproc}
4013 @cindex @code{cfi_startproc} directive
4014 @code{.cfi_startproc} is used at the beginning of each function that
4015 should have an entry in @code{.eh_frame}. It initializes some internal
4016 data structures and emits architecture dependent initial CFI instructions.
4017 Don't forget to close the function by
4018 @code{.cfi_endproc}.
4020 @section @code{.cfi_endproc}
4021 @cindex @code{cfi_endproc} directive
4022 @code{.cfi_endproc} is used at the end of a function where it closes its
4023 unwind entry previously opened by
4024 @code{.cfi_startproc}. and emits it to @code{.eh_frame}.
4026 @section @code{.cfi_def_cfa @var{register}, @var{offset}}
4027 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4028 address from @var{register} and add @var{offset} to it}.
4030 @section @code{.cfi_def_cfa_register @var{register}}
4031 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4032 now on @var{register} will be used instead of the old one. Offset
4035 @section @code{.cfi_def_cfa_offset @var{offset}}
4036 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4037 remains the same, but @var{offset} is new. Note that it is the
4038 absolute offset that will be added to a defined register to compute
4041 @section @code{.cfi_adjust_cfa_offset @var{offset}}
4042 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4043 value that is added/substracted from the previous offset.
4045 @section @code{.cfi_offset @var{register}, @var{offset}}
4046 Previous value of @var{register} is saved at offset @var{offset} from
4049 @section @code{.cfi_rel_offset @var{register}, @var{offset}}
4050 Previous value of @var{register} is saved at offset @var{offset} from
4051 the current CFA register. This is transformed to @code{.cfi_offset}
4052 using the known displacement of the CFA register from the CFA.
4053 This is often easier to use, because the number will match the
4054 code it's annotating.
4056 @section @code{.cfi_window_save}
4057 SPARC register window has been saved.
4059 @section @code{.cfi_escape} @var{expression}[, @dots{}]
4060 Allows the user to add arbitrary bytes to the unwind info. One
4061 might use this to add OS-specific CFI opcodes, or generic CFI
4062 opcodes that GAS does not yet support.
4065 @section @code{.data @var{subsection}}
4067 @cindex @code{data} directive
4068 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4069 end of the data subsection numbered @var{subsection} (which is an
4070 absolute expression). If @var{subsection} is omitted, it defaults
4075 @section @code{.def @var{name}}
4077 @cindex @code{def} directive
4078 @cindex COFF symbols, debugging
4079 @cindex debugging COFF symbols
4080 Begin defining debugging information for a symbol @var{name}; the
4081 definition extends until the @code{.endef} directive is encountered.
4084 This directive is only observed when @command{@value{AS}} is configured for COFF
4085 format output; when producing @code{b.out}, @samp{.def} is recognized,
4092 @section @code{.desc @var{symbol}, @var{abs-expression}}
4094 @cindex @code{desc} directive
4095 @cindex COFF symbol descriptor
4096 @cindex symbol descriptor, COFF
4097 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4098 to the low 16 bits of an absolute expression.
4101 The @samp{.desc} directive is not available when @command{@value{AS}} is
4102 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4103 object format. For the sake of compatibility, @command{@value{AS}} accepts
4104 it, but produces no output, when configured for COFF.
4110 @section @code{.dim}
4112 @cindex @code{dim} directive
4113 @cindex COFF auxiliary symbol information
4114 @cindex auxiliary symbol information, COFF
4115 This directive is generated by compilers to include auxiliary debugging
4116 information in the symbol table. It is only permitted inside
4117 @code{.def}/@code{.endef} pairs.
4120 @samp{.dim} is only meaningful when generating COFF format output; when
4121 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4127 @section @code{.double @var{flonums}}
4129 @cindex @code{double} directive
4130 @cindex floating point numbers (double)
4131 @code{.double} expects zero or more flonums, separated by commas. It
4132 assembles floating point numbers.
4134 The exact kind of floating point numbers emitted depends on how
4135 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4139 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4140 in @sc{ieee} format.
4145 @section @code{.eject}
4147 @cindex @code{eject} directive
4148 @cindex new page, in listings
4149 @cindex page, in listings
4150 @cindex listing control: new page
4151 Force a page break at this point, when generating assembly listings.
4154 @section @code{.else}
4156 @cindex @code{else} directive
4157 @code{.else} is part of the @command{@value{AS}} support for conditional
4158 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
4159 of code to be assembled if the condition for the preceding @code{.if}
4163 @section @code{.elseif}
4165 @cindex @code{elseif} directive
4166 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4167 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
4168 @code{.if} block that would otherwise fill the entire @code{.else} section.
4171 @section @code{.end}
4173 @cindex @code{end} directive
4174 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4175 process anything in the file past the @code{.end} directive.
4179 @section @code{.endef}
4181 @cindex @code{endef} directive
4182 This directive flags the end of a symbol definition begun with
4186 @samp{.endef} is only meaningful when generating COFF format output; if
4187 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4188 directive but ignores it.
4193 @section @code{.endfunc}
4194 @cindex @code{endfunc} directive
4195 @code{.endfunc} marks the end of a function specified with @code{.func}.
4198 @section @code{.endif}
4200 @cindex @code{endif} directive
4201 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4202 it marks the end of a block of code that is only assembled
4203 conditionally. @xref{If,,@code{.if}}.
4206 @section @code{.equ @var{symbol}, @var{expression}}
4208 @cindex @code{equ} directive
4209 @cindex assigning values to symbols
4210 @cindex symbols, assigning values to
4211 This directive sets the value of @var{symbol} to @var{expression}.
4212 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
4215 The syntax for @code{equ} on the HPPA is
4216 @samp{@var{symbol} .equ @var{expression}}.
4220 @section @code{.equiv @var{symbol}, @var{expression}}
4221 @cindex @code{equiv} directive
4222 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4223 the assembler will signal an error if @var{symbol} is already defined. Note a
4224 symbol which has been referenced but not actually defined is considered to be
4227 Except for the contents of the error message, this is roughly equivalent to
4236 @section @code{.err}
4237 @cindex @code{err} directive
4238 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4239 message and, unless the @option{-Z} option was used, it will not generate an
4240 object file. This can be used to signal error an conditionally compiled code.
4243 @section @code{.exitm}
4244 Exit early from the current macro definition. @xref{Macro}.
4247 @section @code{.extern}
4249 @cindex @code{extern} directive
4250 @code{.extern} is accepted in the source program---for compatibility
4251 with other assemblers---but it is ignored. @command{@value{AS}} treats
4252 all undefined symbols as external.
4255 @section @code{.fail @var{expression}}
4257 @cindex @code{fail} directive
4258 Generates an error or a warning. If the value of the @var{expression} is 500
4259 or more, @command{@value{AS}} will print a warning message. If the value is less
4260 than 500, @command{@value{AS}} will print an error message. The message will
4261 include the value of @var{expression}. This can occasionally be useful inside
4262 complex nested macros or conditional assembly.
4264 @ifclear no-file-dir
4266 @section @code{.file @var{string}}
4268 @cindex @code{file} directive
4269 @cindex logical file name
4270 @cindex file name, logical
4271 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4272 file. @var{string} is the new file name. In general, the filename is
4273 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4274 to specify an empty file name, you must give the quotes--@code{""}. This
4275 statement may go away in future: it is only recognized to be compatible with
4276 old @command{@value{AS}} programs.
4278 In some configurations of @command{@value{AS}}, @code{.file} has already been
4279 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4284 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4286 @cindex @code{fill} directive
4287 @cindex writing patterns in memory
4288 @cindex patterns, writing in memory
4289 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4290 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4291 may be zero or more. @var{Size} may be zero or more, but if it is
4292 more than 8, then it is deemed to have the value 8, compatible with
4293 other people's assemblers. The contents of each @var{repeat} bytes
4294 is taken from an 8-byte number. The highest order 4 bytes are
4295 zero. The lowest order 4 bytes are @var{value} rendered in the
4296 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4297 Each @var{size} bytes in a repetition is taken from the lowest order
4298 @var{size} bytes of this number. Again, this bizarre behavior is
4299 compatible with other people's assemblers.
4301 @var{size} and @var{value} are optional.
4302 If the second comma and @var{value} are absent, @var{value} is
4303 assumed zero. If the first comma and following tokens are absent,
4304 @var{size} is assumed to be 1.
4307 @section @code{.float @var{flonums}}
4309 @cindex floating point numbers (single)
4310 @cindex @code{float} directive
4311 This directive assembles zero or more flonums, separated by commas. It
4312 has the same effect as @code{.single}.
4314 The exact kind of floating point numbers emitted depends on how
4315 @command{@value{AS}} is configured.
4316 @xref{Machine Dependencies}.
4320 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4321 in @sc{ieee} format.
4326 @section @code{.func @var{name}[,@var{label}]}
4327 @cindex @code{func} directive
4328 @code{.func} emits debugging information to denote function @var{name}, and
4329 is ignored unless the file is assembled with debugging enabled.
4330 Only @samp{--gstabs[+]} is currently supported.
4331 @var{label} is the entry point of the function and if omitted @var{name}
4332 prepended with the @samp{leading char} is used.
4333 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4334 All functions are currently defined to have @code{void} return type.
4335 The function must be terminated with @code{.endfunc}.
4338 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4340 @cindex @code{global} directive
4341 @cindex symbol, making visible to linker
4342 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4343 @var{symbol} in your partial program, its value is made available to
4344 other partial programs that are linked with it. Otherwise,
4345 @var{symbol} takes its attributes from a symbol of the same name
4346 from another file linked into the same program.
4348 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4349 compatibility with other assemblers.
4352 On the HPPA, @code{.global} is not always enough to make it accessible to other
4353 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4354 @xref{HPPA Directives,, HPPA Assembler Directives}.
4359 @section @code{.hidden @var{names}}
4361 @cindex @code{hidden} directive
4363 This is one of the ELF visibility directives. The other two are
4364 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4365 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4367 This directive overrides the named symbols default visibility (which is set by
4368 their binding: local, global or weak). The directive sets the visibility to
4369 @code{hidden} which means that the symbols are not visible to other components.
4370 Such symbols are always considered to be @code{protected} as well.
4374 @section @code{.hword @var{expressions}}
4376 @cindex @code{hword} directive
4377 @cindex integers, 16-bit
4378 @cindex numbers, 16-bit
4379 @cindex sixteen bit integers
4380 This expects zero or more @var{expressions}, and emits
4381 a 16 bit number for each.
4384 This directive is a synonym for @samp{.short}; depending on the target
4385 architecture, it may also be a synonym for @samp{.word}.
4389 This directive is a synonym for @samp{.short}.
4392 This directive is a synonym for both @samp{.short} and @samp{.word}.
4397 @section @code{.ident}
4399 @cindex @code{ident} directive
4400 This directive is used by some assemblers to place tags in object files.
4401 @command{@value{AS}} simply accepts the directive for source-file
4402 compatibility with such assemblers, but does not actually emit anything
4406 @section @code{.if @var{absolute expression}}
4408 @cindex conditional assembly
4409 @cindex @code{if} directive
4410 @code{.if} marks the beginning of a section of code which is only
4411 considered part of the source program being assembled if the argument
4412 (which must be an @var{absolute expression}) is non-zero. The end of
4413 the conditional section of code must be marked by @code{.endif}
4414 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4415 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4416 If you have several conditions to check, @code{.elseif} may be used to avoid
4417 nesting blocks if/else within each subsequent @code{.else} block.
4419 The following variants of @code{.if} are also supported:
4421 @cindex @code{ifdef} directive
4422 @item .ifdef @var{symbol}
4423 Assembles the following section of code if the specified @var{symbol}
4424 has been defined. Note a symbol which has been referenced but not yet defined
4425 is considered to be undefined.
4427 @cindex @code{ifc} directive
4428 @item .ifc @var{string1},@var{string2}
4429 Assembles the following section of code if the two strings are the same. The
4430 strings may be optionally quoted with single quotes. If they are not quoted,
4431 the first string stops at the first comma, and the second string stops at the
4432 end of the line. Strings which contain whitespace should be quoted. The
4433 string comparison is case sensitive.
4435 @cindex @code{ifeq} directive
4436 @item .ifeq @var{absolute expression}
4437 Assembles the following section of code if the argument is zero.
4439 @cindex @code{ifeqs} directive
4440 @item .ifeqs @var{string1},@var{string2}
4441 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4443 @cindex @code{ifge} directive
4444 @item .ifge @var{absolute expression}
4445 Assembles the following section of code if the argument is greater than or
4448 @cindex @code{ifgt} directive
4449 @item .ifgt @var{absolute expression}
4450 Assembles the following section of code if the argument is greater than zero.
4452 @cindex @code{ifle} directive
4453 @item .ifle @var{absolute expression}
4454 Assembles the following section of code if the argument is less than or equal
4457 @cindex @code{iflt} directive
4458 @item .iflt @var{absolute expression}
4459 Assembles the following section of code if the argument is less than zero.
4461 @cindex @code{ifnc} directive
4462 @item .ifnc @var{string1},@var{string2}.
4463 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4464 following section of code if the two strings are not the same.
4466 @cindex @code{ifndef} directive
4467 @cindex @code{ifnotdef} directive
4468 @item .ifndef @var{symbol}
4469 @itemx .ifnotdef @var{symbol}
4470 Assembles the following section of code if the specified @var{symbol}
4471 has not been defined. Both spelling variants are equivalent. Note a symbol
4472 which has been referenced but not yet defined is considered to be undefined.
4474 @cindex @code{ifne} directive
4475 @item .ifne @var{absolute expression}
4476 Assembles the following section of code if the argument is not equal to zero
4477 (in other words, this is equivalent to @code{.if}).
4479 @cindex @code{ifnes} directive
4480 @item .ifnes @var{string1},@var{string2}
4481 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4482 following section of code if the two strings are not the same.
4486 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4488 @cindex @code{incbin} directive
4489 @cindex binary files, including
4490 The @code{incbin} directive includes @var{file} verbatim at the current
4491 location. You can control the search paths used with the @samp{-I} command-line
4492 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4495 The @var{skip} argument skips a number of bytes from the start of the
4496 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4497 read. Note that the data is not aligned in any way, so it is the user's
4498 responsibility to make sure that proper alignment is provided both before and
4499 after the @code{incbin} directive.
4502 @section @code{.include "@var{file}"}
4504 @cindex @code{include} directive
4505 @cindex supporting files, including
4506 @cindex files, including
4507 This directive provides a way to include supporting files at specified
4508 points in your source program. The code from @var{file} is assembled as
4509 if it followed the point of the @code{.include}; when the end of the
4510 included file is reached, assembly of the original file continues. You
4511 can control the search paths used with the @samp{-I} command-line option
4512 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4516 @section @code{.int @var{expressions}}
4518 @cindex @code{int} directive
4519 @cindex integers, 32-bit
4520 Expect zero or more @var{expressions}, of any section, separated by commas.
4521 For each expression, emit a number that, at run time, is the value of that
4522 expression. The byte order and bit size of the number depends on what kind
4523 of target the assembly is for.
4527 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4528 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
4535 @section @code{.internal @var{names}}
4537 @cindex @code{internal} directive
4539 This is one of the ELF visibility directives. The other two are
4540 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4541 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4543 This directive overrides the named symbols default visibility (which is set by
4544 their binding: local, global or weak). The directive sets the visibility to
4545 @code{internal} which means that the symbols are considered to be @code{hidden}
4546 (i.e., not visible to other components), and that some extra, processor specific
4547 processing must also be performed upon the symbols as well.
4551 @section @code{.irp @var{symbol},@var{values}}@dots{}
4553 @cindex @code{irp} directive
4554 Evaluate a sequence of statements assigning different values to @var{symbol}.
4555 The sequence of statements starts at the @code{.irp} directive, and is
4556 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4557 set to @var{value}, and the sequence of statements is assembled. If no
4558 @var{value} is listed, the sequence of statements is assembled once, with
4559 @var{symbol} set to the null string. To refer to @var{symbol} within the
4560 sequence of statements, use @var{\symbol}.
4562 For example, assembling
4570 is equivalent to assembling
4579 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4581 @cindex @code{irpc} directive
4582 Evaluate a sequence of statements assigning different values to @var{symbol}.
4583 The sequence of statements starts at the @code{.irpc} directive, and is
4584 terminated by an @code{.endr} directive. For each character in @var{value},
4585 @var{symbol} is set to the character, and the sequence of statements is
4586 assembled. If no @var{value} is listed, the sequence of statements is
4587 assembled once, with @var{symbol} set to the null string. To refer to
4588 @var{symbol} within the sequence of statements, use @var{\symbol}.
4590 For example, assembling
4598 is equivalent to assembling
4607 @section @code{.lcomm @var{symbol} , @var{length}}
4609 @cindex @code{lcomm} directive
4610 @cindex local common symbols
4611 @cindex symbols, local common
4612 Reserve @var{length} (an absolute expression) bytes for a local common
4613 denoted by @var{symbol}. The section and value of @var{symbol} are
4614 those of the new local common. The addresses are allocated in the bss
4615 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4616 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4617 not visible to @code{@value{LD}}.
4620 Some targets permit a third argument to be used with @code{.lcomm}. This
4621 argument specifies the desired alignment of the symbol in the bss section.
4625 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4626 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4630 @section @code{.lflags}
4632 @cindex @code{lflags} directive (ignored)
4633 @command{@value{AS}} accepts this directive, for compatibility with other
4634 assemblers, but ignores it.
4636 @ifclear no-line-dir
4638 @section @code{.line @var{line-number}}
4640 @cindex @code{line} directive
4644 @section @code{.ln @var{line-number}}
4646 @cindex @code{ln} directive
4648 @cindex logical line number
4650 Change the logical line number. @var{line-number} must be an absolute
4651 expression. The next line has that logical line number. Therefore any other
4652 statements on the current line (after a statement separator character) are
4653 reported as on logical line number @var{line-number} @minus{} 1. One day
4654 @command{@value{AS}} will no longer support this directive: it is recognized only
4655 for compatibility with existing assembler programs.
4659 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4660 not available; use the synonym @code{.ln} in that context.
4665 @ifclear no-line-dir
4666 Even though this is a directive associated with the @code{a.out} or
4667 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4668 when producing COFF output, and treats @samp{.line} as though it
4669 were the COFF @samp{.ln} @emph{if} it is found outside a
4670 @code{.def}/@code{.endef} pair.
4672 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4673 used by compilers to generate auxiliary symbol information for
4678 @section @code{.linkonce [@var{type}]}
4680 @cindex @code{linkonce} directive
4681 @cindex common sections
4682 Mark the current section so that the linker only includes a single copy of it.
4683 This may be used to include the same section in several different object files,
4684 but ensure that the linker will only include it once in the final output file.
4685 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4686 Duplicate sections are detected based on the section name, so it should be
4689 This directive is only supported by a few object file formats; as of this
4690 writing, the only object file format which supports it is the Portable
4691 Executable format used on Windows NT.
4693 The @var{type} argument is optional. If specified, it must be one of the
4694 following strings. For example:
4698 Not all types may be supported on all object file formats.
4702 Silently discard duplicate sections. This is the default.
4705 Warn if there are duplicate sections, but still keep only one copy.
4708 Warn if any of the duplicates have different sizes.
4711 Warn if any of the duplicates do not have exactly the same contents.
4715 @section @code{.ln @var{line-number}}
4717 @cindex @code{ln} directive
4718 @ifclear no-line-dir
4719 @samp{.ln} is a synonym for @samp{.line}.
4722 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4723 must be an absolute expression. The next line has that logical
4724 line number, so any other statements on the current line (after a
4725 statement separator character @code{;}) are reported as on logical
4726 line number @var{line-number} @minus{} 1.
4729 This directive is accepted, but ignored, when @command{@value{AS}} is
4730 configured for @code{b.out}; its effect is only associated with COFF
4736 @section @code{.mri @var{val}}
4738 @cindex @code{mri} directive
4739 @cindex MRI mode, temporarily
4740 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4741 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4742 affects code assembled until the next @code{.mri} directive, or until the end
4743 of the file. @xref{M, MRI mode, MRI mode}.
4746 @section @code{.list}
4748 @cindex @code{list} directive
4749 @cindex listing control, turning on
4750 Control (in conjunction with the @code{.nolist} directive) whether or
4751 not assembly listings are generated. These two directives maintain an
4752 internal counter (which is zero initially). @code{.list} increments the
4753 counter, and @code{.nolist} decrements it. Assembly listings are
4754 generated whenever the counter is greater than zero.
4756 By default, listings are disabled. When you enable them (with the
4757 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4758 the initial value of the listing counter is one.
4761 @section @code{.long @var{expressions}}
4763 @cindex @code{long} directive
4764 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4767 @c no one seems to know what this is for or whether this description is
4768 @c what it really ought to do
4770 @section @code{.lsym @var{symbol}, @var{expression}}
4772 @cindex @code{lsym} directive
4773 @cindex symbol, not referenced in assembly
4774 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4775 the hash table, ensuring it cannot be referenced by name during the
4776 rest of the assembly. This sets the attributes of the symbol to be
4777 the same as the expression value:
4779 @var{other} = @var{descriptor} = 0
4780 @var{type} = @r{(section of @var{expression})}
4781 @var{value} = @var{expression}
4784 The new symbol is not flagged as external.
4788 @section @code{.macro}
4791 The commands @code{.macro} and @code{.endm} allow you to define macros that
4792 generate assembly output. For example, this definition specifies a macro
4793 @code{sum} that puts a sequence of numbers into memory:
4796 .macro sum from=0, to=5
4805 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4817 @item .macro @var{macname}
4818 @itemx .macro @var{macname} @var{macargs} @dots{}
4819 @cindex @code{macro} directive
4820 Begin the definition of a macro called @var{macname}. If your macro
4821 definition requires arguments, specify their names after the macro name,
4822 separated by commas or spaces. You can supply a default value for any
4823 macro argument by following the name with @samp{=@var{deflt}}. For
4824 example, these are all valid @code{.macro} statements:
4828 Begin the definition of a macro called @code{comm}, which takes no
4831 @item .macro plus1 p, p1
4832 @itemx .macro plus1 p p1
4833 Either statement begins the definition of a macro called @code{plus1},
4834 which takes two arguments; within the macro definition, write
4835 @samp{\p} or @samp{\p1} to evaluate the arguments.
4837 @item .macro reserve_str p1=0 p2
4838 Begin the definition of a macro called @code{reserve_str}, with two
4839 arguments. The first argument has a default value, but not the second.
4840 After the definition is complete, you can call the macro either as
4841 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4842 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4843 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4844 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4847 When you call a macro, you can specify the argument values either by
4848 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4849 @samp{sum to=17, from=9}.
4852 @cindex @code{endm} directive
4853 Mark the end of a macro definition.
4856 @cindex @code{exitm} directive
4857 Exit early from the current macro definition.
4859 @cindex number of macros executed
4860 @cindex macros, count executed
4862 @command{@value{AS}} maintains a counter of how many macros it has
4863 executed in this pseudo-variable; you can copy that number to your
4864 output with @samp{\@@}, but @emph{only within a macro definition}.
4866 @item LOCAL @var{name} [ , @dots{} ]
4867 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4868 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
4869 @xref{Altmacro,,@code{.altmacro}}.
4873 @section @code{.altmacro}
4874 Enable alternate macro mode, enabling:
4877 @item LOCAL @var{name} [ , @dots{} ]
4878 One additional directive, @code{LOCAL}, is available. It is used to
4879 generate a string replacement for each of the @var{name} arguments, and
4880 replace any instances of @var{name} in each macro expansion. The
4881 replacement string is unique in the assembly, and different for each
4882 separate macro expansion. @code{LOCAL} allows you to write macros that
4883 define symbols, without fear of conflict between separate macro expansions.
4885 @item String delimiters
4886 You can write strings delimited in these other ways besides
4887 @code{"@var{string}"}:
4890 @item '@var{string}'
4891 You can delimit strings with single-quote charaters.
4893 @item <@var{string}>
4894 You can delimit strings with matching angle brackets.
4897 @item single-character string escape
4898 To include any single character literally in a string (even if the
4899 character would otherwise have some special meaning), you can prefix the
4900 character with @samp{!} (an exclamation mark). For example, you can
4901 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4903 @item Expression results as strings
4904 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4905 and use the result as a string.
4909 @section @code{.noaltmacro}
4910 Disable alternate macro mode. @ref{Altmacro}
4913 @section @code{.nolist}
4915 @cindex @code{nolist} directive
4916 @cindex listing control, turning off
4917 Control (in conjunction with the @code{.list} directive) whether or
4918 not assembly listings are generated. These two directives maintain an
4919 internal counter (which is zero initially). @code{.list} increments the
4920 counter, and @code{.nolist} decrements it. Assembly listings are
4921 generated whenever the counter is greater than zero.
4924 @section @code{.octa @var{bignums}}
4926 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4927 @cindex @code{octa} directive
4928 @cindex integer, 16-byte
4929 @cindex sixteen byte integer
4930 This directive expects zero or more bignums, separated by commas. For each
4931 bignum, it emits a 16-byte integer.
4933 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4934 hence @emph{octa}-word for 16 bytes.
4937 @section @code{.org @var{new-lc} , @var{fill}}
4939 @cindex @code{org} directive
4940 @cindex location counter, advancing
4941 @cindex advancing location counter
4942 @cindex current address, advancing
4943 Advance the location counter of the current section to
4944 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4945 expression with the same section as the current subsection. That is,
4946 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4947 wrong section, the @code{.org} directive is ignored. To be compatible
4948 with former assemblers, if the section of @var{new-lc} is absolute,
4949 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4950 is the same as the current subsection.
4952 @code{.org} may only increase the location counter, or leave it
4953 unchanged; you cannot use @code{.org} to move the location counter
4956 @c double negative used below "not undefined" because this is a specific
4957 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4958 @c section. doc@cygnus.com 18feb91
4959 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4960 may not be undefined. If you really detest this restriction we eagerly await
4961 a chance to share your improved assembler.
4963 Beware that the origin is relative to the start of the section, not
4964 to the start of the subsection. This is compatible with other
4965 people's assemblers.
4967 When the location counter (of the current subsection) is advanced, the
4968 intervening bytes are filled with @var{fill} which should be an
4969 absolute expression. If the comma and @var{fill} are omitted,
4970 @var{fill} defaults to zero.
4973 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4975 @cindex padding the location counter given a power of two
4976 @cindex @code{p2align} directive
4977 Pad the location counter (in the current subsection) to a particular
4978 storage boundary. The first expression (which must be absolute) is the
4979 number of low-order zero bits the location counter must have after
4980 advancement. For example @samp{.p2align 3} advances the location
4981 counter until it a multiple of 8. If the location counter is already a
4982 multiple of 8, no change is needed.
4984 The second expression (also absolute) gives the fill value to be stored in the
4985 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4986 padding bytes are normally zero. However, on some systems, if the section is
4987 marked as containing code and the fill value is omitted, the space is filled
4988 with no-op instructions.
4990 The third expression is also absolute, and is also optional. If it is present,
4991 it is the maximum number of bytes that should be skipped by this alignment
4992 directive. If doing the alignment would require skipping more bytes than the
4993 specified maximum, then the alignment is not done at all. You can omit the
4994 fill value (the second argument) entirely by simply using two commas after the
4995 required alignment; this can be useful if you want the alignment to be filled
4996 with no-op instructions when appropriate.
4998 @cindex @code{p2alignw} directive
4999 @cindex @code{p2alignl} directive
5000 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5001 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5002 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5003 fill pattern as a four byte longword value. For example, @code{.p2alignw
5004 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5005 filled in with the value 0x368d (the exact placement of the bytes depends upon
5006 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5011 @section @code{.previous}
5013 @cindex @code{previous} directive
5014 @cindex Section Stack
5015 This is one of the ELF section stack manipulation directives. The others are
5016 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5017 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5018 (@pxref{PopSection}).
5020 This directive swaps the current section (and subsection) with most recently
5021 referenced section (and subsection) prior to this one. Multiple
5022 @code{.previous} directives in a row will flip between two sections (and their
5025 In terms of the section stack, this directive swaps the current section with
5026 the top section on the section stack.
5031 @section @code{.popsection}
5033 @cindex @code{popsection} directive
5034 @cindex Section Stack
5035 This is one of the ELF section stack manipulation directives. The others are
5036 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5037 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5040 This directive replaces the current section (and subsection) with the top
5041 section (and subsection) on the section stack. This section is popped off the
5046 @section @code{.print @var{string}}
5048 @cindex @code{print} directive
5049 @command{@value{AS}} will print @var{string} on the standard output during
5050 assembly. You must put @var{string} in double quotes.
5054 @section @code{.protected @var{names}}
5056 @cindex @code{protected} directive
5058 This is one of the ELF visibility directives. The other two are
5059 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
5061 This directive overrides the named symbols default visibility (which is set by
5062 their binding: local, global or weak). The directive sets the visibility to
5063 @code{protected} which means that any references to the symbols from within the
5064 components that defines them must be resolved to the definition in that
5065 component, even if a definition in another component would normally preempt
5070 @section @code{.psize @var{lines} , @var{columns}}
5072 @cindex @code{psize} directive
5073 @cindex listing control: paper size
5074 @cindex paper size, for listings
5075 Use this directive to declare the number of lines---and, optionally, the
5076 number of columns---to use for each page, when generating listings.
5078 If you do not use @code{.psize}, listings use a default line-count
5079 of 60. You may omit the comma and @var{columns} specification; the
5080 default width is 200 columns.
5082 @command{@value{AS}} generates formfeeds whenever the specified number of
5083 lines is exceeded (or whenever you explicitly request one, using
5086 If you specify @var{lines} as @code{0}, no formfeeds are generated save
5087 those explicitly specified with @code{.eject}.
5090 @section @code{.purgem @var{name}}
5092 @cindex @code{purgem} directive
5093 Undefine the macro @var{name}, so that later uses of the string will not be
5094 expanded. @xref{Macro}.
5098 @section @code{.pushsection @var{name} , @var{subsection}}
5100 @cindex @code{pushsection} directive
5101 @cindex Section Stack
5102 This is one of the ELF section stack manipulation directives. The others are
5103 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5104 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5107 This directive pushes the current section (and subsection) onto the
5108 top of the section stack, and then replaces the current section and
5109 subsection with @code{name} and @code{subsection}.
5113 @section @code{.quad @var{bignums}}
5115 @cindex @code{quad} directive
5116 @code{.quad} expects zero or more bignums, separated by commas. For
5117 each bignum, it emits
5119 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
5120 warning message; and just takes the lowest order 8 bytes of the bignum.
5121 @cindex eight-byte integer
5122 @cindex integer, 8-byte
5124 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
5125 hence @emph{quad}-word for 8 bytes.
5128 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
5129 warning message; and just takes the lowest order 16 bytes of the bignum.
5130 @cindex sixteen-byte integer
5131 @cindex integer, 16-byte
5135 @section @code{.rept @var{count}}
5137 @cindex @code{rept} directive
5138 Repeat the sequence of lines between the @code{.rept} directive and the next
5139 @code{.endr} directive @var{count} times.
5141 For example, assembling
5149 is equivalent to assembling
5158 @section @code{.sbttl "@var{subheading}"}
5160 @cindex @code{sbttl} directive
5161 @cindex subtitles for listings
5162 @cindex listing control: subtitle
5163 Use @var{subheading} as the title (third line, immediately after the
5164 title line) when generating assembly listings.
5166 This directive affects subsequent pages, as well as the current page if
5167 it appears within ten lines of the top of a page.
5171 @section @code{.scl @var{class}}
5173 @cindex @code{scl} directive
5174 @cindex symbol storage class (COFF)
5175 @cindex COFF symbol storage class
5176 Set the storage-class value for a symbol. This directive may only be
5177 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
5178 whether a symbol is static or external, or it may record further
5179 symbolic debugging information.
5182 The @samp{.scl} directive is primarily associated with COFF output; when
5183 configured to generate @code{b.out} output format, @command{@value{AS}}
5184 accepts this directive but ignores it.
5190 @section @code{.section @var{name}}
5192 @cindex named section
5193 Use the @code{.section} directive to assemble the following code into a section
5196 This directive is only supported for targets that actually support arbitrarily
5197 named sections; on @code{a.out} targets, for example, it is not accepted, even
5198 with a standard @code{a.out} section name.
5202 @c only print the extra heading if both COFF and ELF are set
5203 @subheading COFF Version
5206 @cindex @code{section} directive (COFF version)
5207 For COFF targets, the @code{.section} directive is used in one of the following
5211 .section @var{name}[, "@var{flags}"]
5212 .section @var{name}[, @var{subsegment}]
5215 If the optional argument is quoted, it is taken as flags to use for the
5216 section. Each flag is a single character. The following flags are recognized:
5219 bss section (uninitialized data)
5221 section is not loaded
5231 shared section (meaningful for PE targets)
5233 ignored. (For compatibility with the ELF version)
5236 If no flags are specified, the default flags depend upon the section name. If
5237 the section name is not recognized, the default will be for the section to be
5238 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
5239 from the section, rather than adding them, so if they are used on their own it
5240 will be as if no flags had been specified at all.
5242 If the optional argument to the @code{.section} directive is not quoted, it is
5243 taken as a subsegment number (@pxref{Sub-Sections}).
5248 @c only print the extra heading if both COFF and ELF are set
5249 @subheading ELF Version
5252 @cindex Section Stack
5253 This is one of the ELF section stack manipulation directives. The others are
5254 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5255 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5256 @code{.previous} (@pxref{Previous}).
5258 @cindex @code{section} directive (ELF version)
5259 For ELF targets, the @code{.section} directive is used like this:
5262 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]
5265 The optional @var{flags} argument is a quoted string which may contain any
5266 combination of the following characters:
5269 section is allocatable
5273 section is executable
5275 section is mergeable
5277 section contains zero terminated strings
5279 section is a member of a section group
5281 section is used for thread-local-storage
5284 The optional @var{type} argument may contain one of the following constants:
5287 section contains data
5289 section does not contain data (i.e., section only occupies space)
5291 section contains data which is used by things other than the program
5293 section contains an array of pointers to init functions
5295 section contains an array of pointers to finish functions
5296 @item @@preinit_array
5297 section contains an array of pointers to pre-init functions
5300 Many targets only support the first three section types.
5302 Note on targets where the @code{@@} character is the start of a comment (eg
5303 ARM) then another character is used instead. For example the ARM port uses the
5306 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
5307 be specified as well as an extra argument - @var{entsize} - like this:
5310 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
5313 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
5314 constants, each @var{entsize} octets long. Sections with both @code{M} and
5315 @code{S} must contain zero terminated strings where each character is
5316 @var{entsize} bytes long. The linker may remove duplicates within sections with
5317 the same name, same entity size and same flags. @var{entsize} must be an
5318 absolute expression.
5320 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
5321 be present along with an additional field like this:
5324 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
5327 The @var{GroupName} field specifies the name of the section group to which this
5328 particular section belongs. The optional linkage field can contain:
5331 indicates that only one copy of this section should be retained
5336 Note - if both the @var{M} and @var{G} flags are present then the fields for
5337 the Merge flag should come first, like this:
5340 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
5343 If no flags are specified, the default flags depend upon the section name. If
5344 the section name is not recognized, the default will be for the section to have
5345 none of the above flags: it will not be allocated in memory, nor writable, nor
5346 executable. The section will contain data.
5348 For ELF targets, the assembler supports another type of @code{.section}
5349 directive for compatibility with the Solaris assembler:
5352 .section "@var{name}"[, @var{flags}...]
5355 Note that the section name is quoted. There may be a sequence of comma
5359 section is allocatable
5363 section is executable
5365 section is used for thread local storage
5368 This directive replaces the current section and subsection. See the
5369 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
5370 some examples of how this directive and the other section stack directives
5376 @section @code{.set @var{symbol}, @var{expression}}
5378 @cindex @code{set} directive
5379 @cindex symbol value, setting
5380 Set the value of @var{symbol} to @var{expression}. This
5381 changes @var{symbol}'s value and type to conform to
5382 @var{expression}. If @var{symbol} was flagged as external, it remains
5383 flagged (@pxref{Symbol Attributes}).
5385 You may @code{.set} a symbol many times in the same assembly.
5387 If you @code{.set} a global symbol, the value stored in the object
5388 file is the last value stored into it.
5391 The syntax for @code{set} on the HPPA is
5392 @samp{@var{symbol} .set @var{expression}}.
5396 @section @code{.short @var{expressions}}
5398 @cindex @code{short} directive
5400 @code{.short} is normally the same as @samp{.word}.
5401 @xref{Word,,@code{.word}}.
5403 In some configurations, however, @code{.short} and @code{.word} generate
5404 numbers of different lengths; @pxref{Machine Dependencies}.
5408 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5411 This expects zero or more @var{expressions}, and emits
5412 a 16 bit number for each.
5417 @section @code{.single @var{flonums}}
5419 @cindex @code{single} directive
5420 @cindex floating point numbers (single)
5421 This directive assembles zero or more flonums, separated by commas. It
5422 has the same effect as @code{.float}.
5424 The exact kind of floating point numbers emitted depends on how
5425 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5429 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5430 numbers in @sc{ieee} format.
5436 @section @code{.size}
5438 This directive is used to set the size associated with a symbol.
5442 @c only print the extra heading if both COFF and ELF are set
5443 @subheading COFF Version
5446 @cindex @code{size} directive (COFF version)
5447 For COFF targets, the @code{.size} directive is only permitted inside
5448 @code{.def}/@code{.endef} pairs. It is used like this:
5451 .size @var{expression}
5455 @samp{.size} is only meaningful when generating COFF format output; when
5456 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5463 @c only print the extra heading if both COFF and ELF are set
5464 @subheading ELF Version
5467 @cindex @code{size} directive (ELF version)
5468 For ELF targets, the @code{.size} directive is used like this:
5471 .size @var{name} , @var{expression}
5474 This directive sets the size associated with a symbol @var{name}.
5475 The size in bytes is computed from @var{expression} which can make use of label
5476 arithmetic. This directive is typically used to set the size of function
5482 @section @code{.sleb128 @var{expressions}}
5484 @cindex @code{sleb128} directive
5485 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5486 compact, variable length representation of numbers used by the DWARF
5487 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5489 @ifclear no-space-dir
5491 @section @code{.skip @var{size} , @var{fill}}
5493 @cindex @code{skip} directive
5494 @cindex filling memory
5495 This directive emits @var{size} bytes, each of value @var{fill}. Both
5496 @var{size} and @var{fill} are absolute expressions. If the comma and
5497 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5501 @section @code{.space @var{size} , @var{fill}}
5503 @cindex @code{space} directive
5504 @cindex filling memory
5505 This directive emits @var{size} bytes, each of value @var{fill}. Both
5506 @var{size} and @var{fill} are absolute expressions. If the comma
5507 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5512 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5513 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5514 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5515 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5524 @section @code{.space}
5525 @cindex @code{space} directive
5527 On the AMD 29K, this directive is ignored; it is accepted for
5528 compatibility with other AMD 29K assemblers.
5531 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5532 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5538 @section @code{.stabd, .stabn, .stabs}
5540 @cindex symbolic debuggers, information for
5541 @cindex @code{stab@var{x}} directives
5542 There are three directives that begin @samp{.stab}.
5543 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5544 The symbols are not entered in the @command{@value{AS}} hash table: they
5545 cannot be referenced elsewhere in the source file.
5546 Up to five fields are required:
5550 This is the symbol's name. It may contain any character except
5551 @samp{\000}, so is more general than ordinary symbol names. Some
5552 debuggers used to code arbitrarily complex structures into symbol names
5556 An absolute expression. The symbol's type is set to the low 8 bits of
5557 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5558 and debuggers choke on silly bit patterns.
5561 An absolute expression. The symbol's ``other'' attribute is set to the
5562 low 8 bits of this expression.
5565 An absolute expression. The symbol's descriptor is set to the low 16
5566 bits of this expression.
5569 An absolute expression which becomes the symbol's value.
5572 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5573 or @code{.stabs} statement, the symbol has probably already been created;
5574 you get a half-formed symbol in your object file. This is
5575 compatible with earlier assemblers!
5578 @cindex @code{stabd} directive
5579 @item .stabd @var{type} , @var{other} , @var{desc}
5581 The ``name'' of the symbol generated is not even an empty string.
5582 It is a null pointer, for compatibility. Older assemblers used a
5583 null pointer so they didn't waste space in object files with empty
5586 The symbol's value is set to the location counter,
5587 relocatably. When your program is linked, the value of this symbol
5588 is the address of the location counter when the @code{.stabd} was
5591 @cindex @code{stabn} directive
5592 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5593 The name of the symbol is set to the empty string @code{""}.
5595 @cindex @code{stabs} directive
5596 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5597 All five fields are specified.
5603 @section @code{.string} "@var{str}"
5605 @cindex string, copying to object file
5606 @cindex @code{string} directive
5608 Copy the characters in @var{str} to the object file. You may specify more than
5609 one string to copy, separated by commas. Unless otherwise specified for a
5610 particular machine, the assembler marks the end of each string with a 0 byte.
5611 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5614 @section @code{.struct @var{expression}}
5616 @cindex @code{struct} directive
5617 Switch to the absolute section, and set the section offset to @var{expression},
5618 which must be an absolute expression. You might use this as follows:
5627 This would define the symbol @code{field1} to have the value 0, the symbol
5628 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5629 value 8. Assembly would be left in the absolute section, and you would need to
5630 use a @code{.section} directive of some sort to change to some other section
5631 before further assembly.
5635 @section @code{.subsection @var{name}}
5637 @cindex @code{subsection} directive
5638 @cindex Section Stack
5639 This is one of the ELF section stack manipulation directives. The others are
5640 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5641 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5644 This directive replaces the current subsection with @code{name}. The current
5645 section is not changed. The replaced subsection is put onto the section stack
5646 in place of the then current top of stack subsection.
5651 @section @code{.symver}
5652 @cindex @code{symver} directive
5653 @cindex symbol versioning
5654 @cindex versions of symbols
5655 Use the @code{.symver} directive to bind symbols to specific version nodes
5656 within a source file. This is only supported on ELF platforms, and is
5657 typically used when assembling files to be linked into a shared library.
5658 There are cases where it may make sense to use this in objects to be bound
5659 into an application itself so as to override a versioned symbol from a
5662 For ELF targets, the @code{.symver} directive can be used like this:
5664 .symver @var{name}, @var{name2@@nodename}
5666 If the symbol @var{name} is defined within the file
5667 being assembled, the @code{.symver} directive effectively creates a symbol
5668 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5669 just don't try and create a regular alias is that the @var{@@} character isn't
5670 permitted in symbol names. The @var{name2} part of the name is the actual name
5671 of the symbol by which it will be externally referenced. The name @var{name}
5672 itself is merely a name of convenience that is used so that it is possible to
5673 have definitions for multiple versions of a function within a single source
5674 file, and so that the compiler can unambiguously know which version of a
5675 function is being mentioned. The @var{nodename} portion of the alias should be
5676 the name of a node specified in the version script supplied to the linker when
5677 building a shared library. If you are attempting to override a versioned
5678 symbol from a shared library, then @var{nodename} should correspond to the
5679 nodename of the symbol you are trying to override.
5681 If the symbol @var{name} is not defined within the file being assembled, all
5682 references to @var{name} will be changed to @var{name2@@nodename}. If no
5683 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5686 Another usage of the @code{.symver} directive is:
5688 .symver @var{name}, @var{name2@@@@nodename}
5690 In this case, the symbol @var{name} must exist and be defined within
5691 the file being assembled. It is similar to @var{name2@@nodename}. The
5692 difference is @var{name2@@@@nodename} will also be used to resolve
5693 references to @var{name2} by the linker.
5695 The third usage of the @code{.symver} directive is:
5697 .symver @var{name}, @var{name2@@@@@@nodename}
5699 When @var{name} is not defined within the
5700 file being assembled, it is treated as @var{name2@@nodename}. When
5701 @var{name} is defined within the file being assembled, the symbol
5702 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5707 @section @code{.tag @var{structname}}
5709 @cindex COFF structure debugging
5710 @cindex structure debugging, COFF
5711 @cindex @code{tag} directive
5712 This directive is generated by compilers to include auxiliary debugging
5713 information in the symbol table. It is only permitted inside
5714 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5715 definitions in the symbol table with instances of those structures.
5718 @samp{.tag} is only used when generating COFF format output; when
5719 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5725 @section @code{.text @var{subsection}}
5727 @cindex @code{text} directive
5728 Tells @command{@value{AS}} to assemble the following statements onto the end of
5729 the text subsection numbered @var{subsection}, which is an absolute
5730 expression. If @var{subsection} is omitted, subsection number zero
5734 @section @code{.title "@var{heading}"}
5736 @cindex @code{title} directive
5737 @cindex listing control: title line
5738 Use @var{heading} as the title (second line, immediately after the
5739 source file name and pagenumber) when generating assembly listings.
5741 This directive affects subsequent pages, as well as the current page if
5742 it appears within ten lines of the top of a page.
5746 @section @code{.type}
5748 This directive is used to set the type of a symbol.
5752 @c only print the extra heading if both COFF and ELF are set
5753 @subheading COFF Version
5756 @cindex COFF symbol type
5757 @cindex symbol type, COFF
5758 @cindex @code{type} directive (COFF version)
5759 For COFF targets, this directive is permitted only within
5760 @code{.def}/@code{.endef} pairs. It is used like this:
5766 This records the integer @var{int} as the type attribute of a symbol table
5770 @samp{.type} is associated only with COFF format output; when
5771 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5772 directive but ignores it.
5778 @c only print the extra heading if both COFF and ELF are set
5779 @subheading ELF Version
5782 @cindex ELF symbol type
5783 @cindex symbol type, ELF
5784 @cindex @code{type} directive (ELF version)
5785 For ELF targets, the @code{.type} directive is used like this:
5788 .type @var{name} , @var{type description}
5791 This sets the type of symbol @var{name} to be either a
5792 function symbol or an object symbol. There are five different syntaxes
5793 supported for the @var{type description} field, in order to provide
5794 compatibility with various other assemblers. The syntaxes supported are:
5797 .type <name>,#function
5798 .type <name>,#object
5800 .type <name>,@@function
5801 .type <name>,@@object
5803 .type <name>,%function
5804 .type <name>,%object
5806 .type <name>,"function"
5807 .type <name>,"object"
5809 .type <name> STT_FUNCTION
5810 .type <name> STT_OBJECT
5816 @section @code{.uleb128 @var{expressions}}
5818 @cindex @code{uleb128} directive
5819 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5820 compact, variable length representation of numbers used by the DWARF
5821 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5825 @section @code{.val @var{addr}}
5827 @cindex @code{val} directive
5828 @cindex COFF value attribute
5829 @cindex value attribute, COFF
5830 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5831 records the address @var{addr} as the value attribute of a symbol table
5835 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5836 configured for @code{b.out}, it accepts this directive but ignores it.
5842 @section @code{.version "@var{string}"}
5844 @cindex @code{version} directive
5845 This directive creates a @code{.note} section and places into it an ELF
5846 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5851 @section @code{.vtable_entry @var{table}, @var{offset}}
5853 @cindex @code{vtable_entry} directive
5854 This directive finds or creates a symbol @code{table} and creates a
5855 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5858 @section @code{.vtable_inherit @var{child}, @var{parent}}
5860 @cindex @code{vtable_inherit} directive
5861 This directive finds the symbol @code{child} and finds or creates the symbol
5862 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5863 parent whose addend is the value of the child symbol. As a special case the
5864 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5868 @section @code{.weak @var{names}}
5870 @cindex @code{weak} directive
5871 This directive sets the weak attribute on the comma separated list of symbol
5872 @code{names}. If the symbols do not already exist, they will be created.
5874 Weak symbols are supported in COFF as a GNU extension. This directive
5875 sets the weak attribute on the comma separated list of symbol
5876 @code{names}. If the symbols do not already exist, they will be created.
5879 @code{.weak @var{name} [ < = | == > @var{alternate}] [, ...]}
5882 On the PE target, weak aliases are supported natively. Weak aliases
5883 (usually called "weak externals" in PE) are created when an alternate
5884 name is specified. When a weak symbol is linked and the symbol is not
5885 defined, the weak symbol becomes an alias for the alternate symbol. If
5886 one equal sign is used, the linker searches for defined symbols within
5887 other objects and libraries. This is the usual mode, historically
5888 called "lazy externals." Otherwise, when two equal signs are used,
5889 the linker searches for defined symbols only within other objects.
5891 Non-alias weak symbols are supported on PE as a GNU extension.
5894 @section @code{.word @var{expressions}}
5896 @cindex @code{word} directive
5897 This directive expects zero or more @var{expressions}, of any section,
5898 separated by commas.
5901 For each expression, @command{@value{AS}} emits a 32-bit number.
5904 For each expression, @command{@value{AS}} emits a 16-bit number.
5909 The size of the number emitted, and its byte order,
5910 depend on what target computer the assembly is for.
5913 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5914 @c happen---32-bit addressability, period; no long/short jumps.
5915 @ifset DIFF-TBL-KLUGE
5916 @cindex difference tables altered
5917 @cindex altered difference tables
5919 @emph{Warning: Special Treatment to support Compilers}
5923 Machines with a 32-bit address space, but that do less than 32-bit
5924 addressing, require the following special treatment. If the machine of
5925 interest to you does 32-bit addressing (or doesn't require it;
5926 @pxref{Machine Dependencies}), you can ignore this issue.
5929 In order to assemble compiler output into something that works,
5930 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5931 Directives of the form @samp{.word sym1-sym2} are often emitted by
5932 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5933 directive of the form @samp{.word sym1-sym2}, and the difference between
5934 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5935 creates a @dfn{secondary jump table}, immediately before the next label.
5936 This secondary jump table is preceded by a short-jump to the
5937 first byte after the secondary table. This short-jump prevents the flow
5938 of control from accidentally falling into the new table. Inside the
5939 table is a long-jump to @code{sym2}. The original @samp{.word}
5940 contains @code{sym1} minus the address of the long-jump to
5943 If there were several occurrences of @samp{.word sym1-sym2} before the
5944 secondary jump table, all of them are adjusted. If there was a
5945 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5946 long-jump to @code{sym4} is included in the secondary jump table,
5947 and the @code{.word} directives are adjusted to contain @code{sym3}
5948 minus the address of the long-jump to @code{sym4}; and so on, for as many
5949 entries in the original jump table as necessary.
5952 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5953 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5954 assembly language programmers.
5957 @c end DIFF-TBL-KLUGE
5960 @section Deprecated Directives
5962 @cindex deprecated directives
5963 @cindex obsolescent directives
5964 One day these directives won't work.
5965 They are included for compatibility with older assemblers.
5972 @node Machine Dependencies
5973 @chapter Machine Dependent Features
5975 @cindex machine dependencies
5976 The machine instruction sets are (almost by definition) different on
5977 each machine where @command{@value{AS}} runs. Floating point representations
5978 vary as well, and @command{@value{AS}} often supports a few additional
5979 directives or command-line options for compatibility with other
5980 assemblers on a particular platform. Finally, some versions of
5981 @command{@value{AS}} support special pseudo-instructions for branch
5984 This chapter discusses most of these differences, though it does not
5985 include details on any machine's instruction set. For details on that
5986 subject, see the hardware manufacturer's manual.
5990 * AMD29K-Dependent:: AMD 29K Dependent Features
5993 * Alpha-Dependent:: Alpha Dependent Features
5996 * ARC-Dependent:: ARC Dependent Features
5999 * ARM-Dependent:: ARM Dependent Features
6002 * CRIS-Dependent:: CRIS Dependent Features
6005 * D10V-Dependent:: D10V Dependent Features
6008 * D30V-Dependent:: D30V Dependent Features
6011 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6014 * H8/500-Dependent:: Renesas H8/500 Dependent Features
6017 * HPPA-Dependent:: HPPA Dependent Features
6020 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
6023 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
6026 * i860-Dependent:: Intel 80860 Dependent Features
6029 * i960-Dependent:: Intel 80960 Dependent Features
6032 * IP2K-Dependent:: IP2K Dependent Features
6035 * M32R-Dependent:: M32R Dependent Features
6038 * M68K-Dependent:: M680x0 Dependent Features
6041 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
6044 * M88K-Dependent:: M880x0 Dependent Features
6047 * MIPS-Dependent:: MIPS Dependent Features
6050 * MMIX-Dependent:: MMIX Dependent Features
6053 * MSP430-Dependent:: MSP430 Dependent Features
6056 * SH-Dependent:: Renesas / SuperH SH Dependent Features
6057 * SH64-Dependent:: SuperH SH64 Dependent Features
6060 * PDP-11-Dependent:: PDP-11 Dependent Features
6063 * PJ-Dependent:: picoJava Dependent Features
6066 * PPC-Dependent:: PowerPC Dependent Features
6069 * Sparc-Dependent:: SPARC Dependent Features
6072 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
6075 * V850-Dependent:: V850 Dependent Features
6078 * Xtensa-Dependent:: Xtensa Dependent Features
6081 * Z8000-Dependent:: Z8000 Dependent Features
6084 * Vax-Dependent:: VAX Dependent Features
6091 @c The following major nodes are *sections* in the GENERIC version, *chapters*
6092 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
6093 @c peculiarity: to preserve cross-references, there must be a node called
6094 @c "Machine Dependencies". Hence the conditional nodenames in each
6095 @c major node below. Node defaulting in makeinfo requires adjacency of
6096 @c node and sectioning commands; hence the repetition of @chapter BLAH
6097 @c in both conditional blocks.
6100 @include c-a29k.texi
6104 @include c-alpha.texi
6116 @include c-cris.texi
6121 @node Machine Dependencies
6122 @chapter Machine Dependent Features
6124 The machine instruction sets are different on each Renesas chip family,
6125 and there are also some syntax differences among the families. This
6126 chapter describes the specific @command{@value{AS}} features for each
6130 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6131 * H8/500-Dependent:: Renesas H8/500 Dependent Features
6132 * SH-Dependent:: Renesas SH Dependent Features
6139 @include c-d10v.texi
6143 @include c-d30v.texi
6147 @include c-h8300.texi
6151 @include c-h8500.texi
6155 @include c-hppa.texi
6159 @include c-i370.texi
6163 @include c-i386.texi
6167 @include c-i860.texi
6171 @include c-i960.texi
6175 @include c-ia64.texi
6179 @include c-ip2k.texi
6183 @include c-m32r.texi
6187 @include c-m68k.texi
6191 @include c-m68hc11.texi
6195 @include c-m88k.texi
6199 @include c-mips.texi
6203 @include c-mmix.texi
6207 @include c-msp430.texi
6211 @include c-ns32k.texi
6215 @include c-pdp11.texi
6228 @include c-sh64.texi
6232 @include c-sparc.texi
6236 @include c-tic54x.texi
6248 @include c-v850.texi
6252 @include c-xtensa.texi
6256 @c reverse effect of @down at top of generic Machine-Dep chapter
6260 @node Reporting Bugs
6261 @chapter Reporting Bugs
6262 @cindex bugs in assembler
6263 @cindex reporting bugs in assembler
6265 Your bug reports play an essential role in making @command{@value{AS}} reliable.
6267 Reporting a bug may help you by bringing a solution to your problem, or it may
6268 not. But in any case the principal function of a bug report is to help the
6269 entire community by making the next version of @command{@value{AS}} work better.
6270 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
6272 In order for a bug report to serve its purpose, you must include the
6273 information that enables us to fix the bug.
6276 * Bug Criteria:: Have you found a bug?
6277 * Bug Reporting:: How to report bugs
6281 @section Have You Found a Bug?
6282 @cindex bug criteria
6284 If you are not sure whether you have found a bug, here are some guidelines:
6287 @cindex fatal signal
6288 @cindex assembler crash
6289 @cindex crash of assembler
6291 If the assembler gets a fatal signal, for any input whatever, that is a
6292 @command{@value{AS}} bug. Reliable assemblers never crash.
6294 @cindex error on valid input
6296 If @command{@value{AS}} produces an error message for valid input, that is a bug.
6298 @cindex invalid input
6300 If @command{@value{AS}} does not produce an error message for invalid input, that
6301 is a bug. However, you should note that your idea of ``invalid input'' might
6302 be our idea of ``an extension'' or ``support for traditional practice''.
6305 If you are an experienced user of assemblers, your suggestions for improvement
6306 of @command{@value{AS}} are welcome in any case.
6310 @section How to Report Bugs
6312 @cindex assembler bugs, reporting
6314 A number of companies and individuals offer support for @sc{gnu} products. If
6315 you obtained @command{@value{AS}} from a support organization, we recommend you
6316 contact that organization first.
6318 You can find contact information for many support companies and
6319 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
6322 In any event, we also recommend that you send bug reports for @command{@value{AS}}
6323 to @samp{bug-binutils@@gnu.org}.
6325 The fundamental principle of reporting bugs usefully is this:
6326 @strong{report all the facts}. If you are not sure whether to state a
6327 fact or leave it out, state it!
6329 Often people omit facts because they think they know what causes the problem
6330 and assume that some details do not matter. Thus, you might assume that the
6331 name of a symbol you use in an example does not matter. Well, probably it does
6332 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
6333 happens to fetch from the location where that name is stored in memory;
6334 perhaps, if the name were different, the contents of that location would fool
6335 the assembler into doing the right thing despite the bug. Play it safe and
6336 give a specific, complete example. That is the easiest thing for you to do,
6337 and the most helpful.
6339 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
6340 it is new to us. Therefore, always write your bug reports on the assumption
6341 that the bug has not been reported previously.
6343 Sometimes people give a few sketchy facts and ask, ``Does this ring a
6344 bell?'' This cannot help us fix a bug, so it is basically useless. We
6345 respond by asking for enough details to enable us to investigate.
6346 You might as well expedite matters by sending them to begin with.
6348 To enable us to fix the bug, you should include all these things:
6352 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
6353 it with the @samp{--version} argument.
6355 Without this, we will not know whether there is any point in looking for
6356 the bug in the current version of @command{@value{AS}}.
6359 Any patches you may have applied to the @command{@value{AS}} source.
6362 The type of machine you are using, and the operating system name and
6366 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
6370 The command arguments you gave the assembler to assemble your example and
6371 observe the bug. To guarantee you will not omit something important, list them
6372 all. A copy of the Makefile (or the output from make) is sufficient.
6374 If we were to try to guess the arguments, we would probably guess wrong
6375 and then we might not encounter the bug.
6378 A complete input file that will reproduce the bug. If the bug is observed when
6379 the assembler is invoked via a compiler, send the assembler source, not the
6380 high level language source. Most compilers will produce the assembler source
6381 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
6382 the options @samp{-v --save-temps}; this will save the assembler source in a
6383 file with an extension of @file{.s}, and also show you exactly how
6384 @command{@value{AS}} is being run.
6387 A description of what behavior you observe that you believe is
6388 incorrect. For example, ``It gets a fatal signal.''
6390 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
6391 will certainly notice it. But if the bug is incorrect output, we might not
6392 notice unless it is glaringly wrong. You might as well not give us a chance to
6395 Even if the problem you experience is a fatal signal, you should still say so
6396 explicitly. Suppose something strange is going on, such as, your copy of
6397 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
6398 library on your system. (This has happened!) Your copy might crash and ours
6399 would not. If you told us to expect a crash, then when ours fails to crash, we
6400 would know that the bug was not happening for us. If you had not told us to
6401 expect a crash, then we would not be able to draw any conclusion from our
6405 If you wish to suggest changes to the @command{@value{AS}} source, send us context
6406 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
6407 option. Always send diffs from the old file to the new file. If you even
6408 discuss something in the @command{@value{AS}} source, refer to it by context, not
6411 The line numbers in our development sources will not match those in your
6412 sources. Your line numbers would convey no useful information to us.
6415 Here are some things that are not necessary:
6419 A description of the envelope of the bug.
6421 Often people who encounter a bug spend a lot of time investigating
6422 which changes to the input file will make the bug go away and which
6423 changes will not affect it.
6425 This is often time consuming and not very useful, because the way we
6426 will find the bug is by running a single example under the debugger
6427 with breakpoints, not by pure deduction from a series of examples.
6428 We recommend that you save your time for something else.
6430 Of course, if you can find a simpler example to report @emph{instead}
6431 of the original one, that is a convenience for us. Errors in the
6432 output will be easier to spot, running under the debugger will take
6433 less time, and so on.
6435 However, simplification is not vital; if you do not want to do this,
6436 report the bug anyway and send us the entire test case you used.
6439 A patch for the bug.
6441 A patch for the bug does help us if it is a good one. But do not omit
6442 the necessary information, such as the test case, on the assumption that
6443 a patch is all we need. We might see problems with your patch and decide
6444 to fix the problem another way, or we might not understand it at all.
6446 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6447 construct an example that will make the program follow a certain path through
6448 the code. If you do not send us the example, we will not be able to construct
6449 one, so we will not be able to verify that the bug is fixed.
6451 And if we cannot understand what bug you are trying to fix, or why your
6452 patch should be an improvement, we will not install it. A test case will
6453 help us to understand.
6456 A guess about what the bug is or what it depends on.
6458 Such guesses are usually wrong. Even we cannot guess right about such
6459 things without first using the debugger to find the facts.
6462 @node Acknowledgements
6463 @chapter Acknowledgements
6465 If you have contributed to GAS and your name isn't listed here,
6466 it is not meant as a slight. We just don't know about it. Send mail to the
6467 maintainer, and we'll correct the situation. Currently
6469 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6471 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6474 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6475 information and the 68k series machines, most of the preprocessing pass, and
6476 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6478 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6479 many bug fixes, including merging support for several processors, breaking GAS
6480 up to handle multiple object file format back ends (including heavy rewrite,
6481 testing, an integration of the coff and b.out back ends), adding configuration
6482 including heavy testing and verification of cross assemblers and file splits
6483 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6484 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6485 port (including considerable amounts of reverse engineering), a SPARC opcode
6486 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6487 assertions and made them work, much other reorganization, cleanup, and lint.
6489 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6490 in format-specific I/O modules.
6492 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6493 has done much work with it since.
6495 The Intel 80386 machine description was written by Eliot Dresselhaus.
6497 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6499 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6500 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6502 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6503 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6504 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6505 support a.out format.
6507 Support for the Zilog Z8k and Renesas H8/300 and H8/500 processors (tc-z8k,
6508 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6509 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6510 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6513 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6514 simplified the configuration of which versions accept which directives. He
6515 updated the 68k machine description so that Motorola's opcodes always produced
6516 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
6517 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6518 cross-compilation support, and one bug in relaxation that took a week and
6519 required the proverbial one-bit fix.
6521 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6522 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6523 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6524 PowerPC assembler, and made a few other minor patches.
6526 Steve Chamberlain made GAS able to generate listings.
6528 Hewlett-Packard contributed support for the HP9000/300.
6530 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6531 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6532 formats). This work was supported by both the Center for Software Science at
6533 the University of Utah and Cygnus Support.
6535 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6536 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6537 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6538 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6539 and some initial 64-bit support).
6541 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
6543 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6544 support for openVMS/Alpha.
6546 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6549 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
6550 Inc. added support for Xtensa processors.
6552 Several engineers at Cygnus Support have also provided many small bug fixes and
6553 configuration enhancements.
6555 Many others have contributed large or small bugfixes and enhancements. If
6556 you have contributed significant work and are not mentioned on this list, and
6557 want to be, let us know. Some of the history has been lost; we are not
6558 intentionally leaving anyone out.
projects / thirdparty / binutils-gdb.git / blob