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 @c Deprecated -- deliberately not documented.
284 @emph{Target D10V options:}
289 @emph{Target D30V options:}
290 [@b{-O}|@b{-n}|@b{-N}]
293 @c Renesas family chips have no machine-dependent assembler options
296 @c HPPA has no machine-dependent assembler options (yet).
300 @emph{Target i386 options:}
301 [@b{--32}|@b{--64}] [@b{-n}]
305 @emph{Target i960 options:}
306 @c see md_parse_option in tc-i960.c
307 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
309 [@b{-b}] [@b{-no-relax}]
313 @emph{Target IA-64 options:}
314 [@b{-mconstant-gp}|@b{-mauto-pic}]
315 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
317 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
321 @emph{Target IP2K options:}
322 [@b{-mip2022}|@b{-mip2022ext}]
326 @emph{Target M32R options:}
327 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
332 @emph{Target M680X0 options:}
333 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
337 @emph{Target M68HC11 options:}
338 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}]
339 [@b{-mshort}|@b{-mlong}]
340 [@b{-mshort-double}|@b{-mlong-double}]
341 [@b{--force-long-branchs}] [@b{--short-branchs}]
342 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
343 [@b{--print-opcodes}] [@b{--generate-example}]
347 @emph{Target MCORE options:}
348 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
349 [@b{-mcpu=[210|340]}]
353 @emph{Target MIPS options:}
354 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
355 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
356 [@b{-non_shared}] [@b{-xgot}]
357 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
358 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
359 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
360 [@b{-mips64}] [@b{-mips64r2}]
361 [@b{-construct-floats}] [@b{-no-construct-floats}]
362 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
363 [@b{-mfix7000}] [@b{-mno-fix7000}]
364 [@b{-mips16}] [@b{-no-mips16}]
365 [@b{-mips3d}] [@b{-no-mips3d}]
366 [@b{-mdmx}] [@b{-no-mdmx}]
367 [@b{-mdebug}] [@b{-no-mdebug}]
368 [@b{-mpdr}] [@b{-mno-pdr}]
372 @emph{Target MMIX options:}
373 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
374 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
375 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
376 [@b{--linker-allocated-gregs}]
380 @emph{Target PDP11 options:}
381 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
382 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
383 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
387 @emph{Target picoJava options:}
392 @emph{Target PowerPC options:}
393 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
394 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
395 @b{-mbooke32}|@b{-mbooke64}]
396 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
397 [@b{-mregnames}|@b{-mno-regnames}]
398 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
399 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
400 [@b{-msolaris}|@b{-mno-solaris}]
404 @emph{Target SPARC options:}
405 @c The order here is important. See c-sparc.texi.
406 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
407 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
408 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
413 @emph{Target TIC54X options:}
414 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
415 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
418 @c Z8000 has no machine-dependent assembler options
422 @emph{Target Xtensa options:}
423 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
424 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
425 [@b{--[no-]transform}]
434 Turn on listings, in any of a variety of ways:
438 omit false conditionals
441 omit debugging directives
444 include high-level source
450 include macro expansions
453 omit forms processing
459 set the name of the listing file
462 You may combine these options; for example, use @samp{-aln} for assembly
463 listing without forms processing. The @samp{=file} option, if used, must be
464 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
467 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
470 Ignored. This option is accepted for script compatibility with calls to
473 @item --defsym @var{sym}=@var{value}
474 Define the symbol @var{sym} to be @var{value} before assembling the input file.
475 @var{value} must be an integer constant. As in C, a leading @samp{0x}
476 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
479 ``fast''---skip whitespace and comment preprocessing (assume source is
484 Generate debugging information for each assembler source line using whichever
485 debug format is preferred by the target. This currently means either STABS,
489 Generate stabs debugging information for each assembler line. This
490 may help debugging assembler code, if the debugger can handle it.
493 Generate stabs debugging information for each assembler line, with GNU
494 extensions that probably only gdb can handle, and that could make other
495 debuggers crash or refuse to read your program. This
496 may help debugging assembler code. Currently the only GNU extension is
497 the location of the current working directory at assembling time.
500 Generate DWARF2 debugging information for each assembler line. This
501 may help debugging assembler code, if the debugger can handle it. Note---this
502 option is only supported by some targets, not all of them.
505 Print a summary of the command line options and exit.
508 Print a summary of all target specific options and exit.
511 Add directory @var{dir} to the search list for @code{.include} directives.
514 Don't warn about signed overflow.
517 @ifclear DIFF-TBL-KLUGE
518 This option is accepted but has no effect on the @value{TARGET} family.
520 @ifset DIFF-TBL-KLUGE
521 Issue warnings when difference tables altered for long displacements.
526 Keep (in the symbol table) local symbols. On traditional a.out systems
527 these start with @samp{L}, but different systems have different local
530 @item --listing-lhs-width=@var{number}
531 Set the maximum width, in words, of the output data column for an assembler
532 listing to @var{number}.
534 @item --listing-lhs-width2=@var{number}
535 Set the maximum width, in words, of the output data column for continuation
536 lines in an assembler listing to @var{number}.
538 @item --listing-rhs-width=@var{number}
539 Set the maximum width of an input source line, as displayed in a listing, to
542 @item --listing-cont-lines=@var{number}
543 Set the maximum number of lines printed in a listing for a single line of input
546 @item -o @var{objfile}
547 Name the object-file output from @command{@value{AS}} @var{objfile}.
550 Fold the data section into the text section.
553 Print the maximum space (in bytes) and total time (in seconds) used by
556 @item --strip-local-absolute
557 Remove local absolute symbols from the outgoing symbol table.
561 Print the @command{as} version.
564 Print the @command{as} version and exit.
568 Suppress warning messages.
570 @item --fatal-warnings
571 Treat warnings as errors.
574 Don't suppress warning messages or treat them as errors.
583 Generate an object file even after errors.
585 @item -- | @var{files} @dots{}
586 Standard input, or source files to assemble.
591 The following options are available when @value{AS} is configured for
596 This option selects the core processor variant.
598 Select either big-endian (-EB) or little-endian (-EL) output.
603 The following options are available when @value{AS} is configured for the ARM
607 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
608 Specify which ARM processor variant is the target.
609 @item -march=@var{architecture}[+@var{extension}@dots{}]
610 Specify which ARM architecture variant is used by the target.
611 @item -mfpu=@var{floating-point-format}
612 Select which Floating Point architecture is the target.
613 @item -mfloat-abi=@var{abi}
614 Select which floating point ABI is in use.
616 Enable Thumb only instruction decoding.
617 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
618 Select which procedure calling convention is in use.
620 Select either big-endian (-EB) or little-endian (-EL) output.
621 @item -mthumb-interwork
622 Specify that the code has been generated with interworking between Thumb and
625 Specify that PIC code has been generated.
630 See the info pages for documentation of the CRIS-specific options.
634 The following options are available when @value{AS} is configured for
637 @cindex D10V optimization
638 @cindex optimization, D10V
640 Optimize output by parallelizing instructions.
645 The following options are available when @value{AS} is configured for a D30V
648 @cindex D30V optimization
649 @cindex optimization, D30V
651 Optimize output by parallelizing instructions.
655 Warn when nops are generated.
657 @cindex D30V nops after 32-bit multiply
659 Warn when a nop after a 32-bit multiply instruction is generated.
664 The following options are available when @value{AS} is configured for the
665 Intel 80960 processor.
668 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
669 Specify which variant of the 960 architecture is the target.
672 Add code to collect statistics about branches taken.
675 Do not alter compare-and-branch instructions for long displacements;
682 The following options are available when @value{AS} is configured for the
688 Specifies that the extended IP2022 instructions are allowed.
691 Restores the default behaviour, which restricts the permitted instructions to
692 just the basic IP2022 ones.
698 The following options are available when @value{AS} is configured for the
699 Renesas M32R (formerly Mitsubishi M32R) series.
704 Specify which processor in the M32R family is the target. The default
705 is normally the M32R, but this option changes it to the M32RX.
707 @item --warn-explicit-parallel-conflicts or --Wp
708 Produce warning messages when questionable parallel constructs are
711 @item --no-warn-explicit-parallel-conflicts or --Wnp
712 Do not produce warning messages when questionable parallel constructs are
719 The following options are available when @value{AS} is configured for the
720 Motorola 68000 series.
725 Shorten references to undefined symbols, to one word instead of two.
727 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
728 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
729 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
730 Specify what processor in the 68000 family is the target. The default
731 is normally the 68020, but this can be changed at configuration time.
733 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
734 The target machine does (or does not) have a floating-point coprocessor.
735 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
736 the basic 68000 is not compatible with the 68881, a combination of the
737 two can be specified, since it's possible to do emulation of the
738 coprocessor instructions with the main processor.
740 @item -m68851 | -mno-68851
741 The target machine does (or does not) have a memory-management
742 unit coprocessor. The default is to assume an MMU for 68020 and up.
749 For details about the PDP-11 machine dependent features options,
750 see @ref{PDP-11-Options}.
753 @item -mpic | -mno-pic
754 Generate position-independent (or position-dependent) code. The
755 default is @option{-mpic}.
758 @itemx -mall-extensions
759 Enable all instruction set extensions. This is the default.
761 @item -mno-extensions
762 Disable all instruction set extensions.
764 @item -m@var{extension} | -mno-@var{extension}
765 Enable (or disable) a particular instruction set extension.
768 Enable the instruction set extensions supported by a particular CPU, and
769 disable all other extensions.
771 @item -m@var{machine}
772 Enable the instruction set extensions supported by a particular machine
773 model, and disable all other extensions.
779 The following options are available when @value{AS} is configured for
780 a picoJava processor.
784 @cindex PJ endianness
785 @cindex endianness, PJ
786 @cindex big endian output, PJ
788 Generate ``big endian'' format output.
790 @cindex little endian output, PJ
792 Generate ``little endian'' format output.
798 The following options are available when @value{AS} is configured for the
799 Motorola 68HC11 or 68HC12 series.
803 @item -m68hc11 | -m68hc12 | -m68hcs12
804 Specify what processor is the target. The default is
805 defined by the configuration option when building the assembler.
808 Specify to use the 16-bit integer ABI.
811 Specify to use the 32-bit integer ABI.
814 Specify to use the 32-bit double ABI.
817 Specify to use the 64-bit double ABI.
819 @item --force-long-branchs
820 Relative branches are turned into absolute ones. This concerns
821 conditional branches, unconditional branches and branches to a
824 @item -S | --short-branchs
825 Do not turn relative branchs into absolute ones
826 when the offset is out of range.
828 @item --strict-direct-mode
829 Do not turn the direct addressing mode into extended addressing mode
830 when the instruction does not support direct addressing mode.
832 @item --print-insn-syntax
833 Print the syntax of instruction in case of error.
835 @item --print-opcodes
836 print the list of instructions with syntax and then exit.
838 @item --generate-example
839 print an example of instruction for each possible instruction and then exit.
840 This option is only useful for testing @command{@value{AS}}.
846 The following options are available when @command{@value{AS}} is configured
847 for the SPARC architecture:
850 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
851 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
852 Explicitly select a variant of the SPARC architecture.
854 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
855 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
857 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
858 UltraSPARC extensions.
860 @item -xarch=v8plus | -xarch=v8plusa
861 For compatibility with the Solaris v9 assembler. These options are
862 equivalent to -Av8plus and -Av8plusa, respectively.
865 Warn when the assembler switches to another architecture.
870 The following options are available when @value{AS} is configured for the 'c54x
875 Enable extended addressing mode. All addresses and relocations will assume
876 extended addressing (usually 23 bits).
877 @item -mcpu=@var{CPU_VERSION}
878 Sets the CPU version being compiled for.
879 @item -merrors-to-file @var{FILENAME}
880 Redirect error output to a file, for broken systems which don't support such
881 behaviour in the shell.
886 The following options are available when @value{AS} is configured for
887 a @sc{mips} processor.
891 This option sets the largest size of an object that can be referenced
892 implicitly with the @code{gp} register. It is only accepted for targets that
893 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
895 @cindex MIPS endianness
896 @cindex endianness, MIPS
897 @cindex big endian output, MIPS
899 Generate ``big endian'' format output.
901 @cindex little endian output, MIPS
903 Generate ``little endian'' format output.
915 Generate code for a particular @sc{mips} Instruction Set Architecture level.
916 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
917 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
918 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
919 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and
921 correspond to generic
922 @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64},
923 and @samp{MIPS64 Release 2}
924 ISA processors, respectively.
926 @item -march=@var{CPU}
927 Generate code for a particular @sc{mips} cpu.
929 @item -mtune=@var{cpu}
930 Schedule and tune for a particular @sc{mips} cpu.
934 Cause nops to be inserted if the read of the destination register
935 of an mfhi or mflo instruction occurs in the following two instructions.
939 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
940 section instead of the standard ELF .stabs sections.
944 Control generation of @code{.pdr} sections.
948 The register sizes are normally inferred from the ISA and ABI, but these
949 flags force a certain group of registers to be treated as 32 bits wide at
950 all times. @samp{-mgp32} controls the size of general-purpose registers
951 and @samp{-mfp32} controls the size of floating-point registers.
955 Generate code for the MIPS 16 processor. This is equivalent to putting
956 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
957 turns off this option.
961 Generate code for the MIPS-3D Application Specific Extension.
962 This tells the assembler to accept MIPS-3D instructions.
963 @samp{-no-mips3d} turns off this option.
967 Generate code for the MDMX Application Specific Extension.
968 This tells the assembler to accept MDMX instructions.
969 @samp{-no-mdmx} turns off this option.
971 @item --construct-floats
972 @itemx --no-construct-floats
973 The @samp{--no-construct-floats} option disables the construction of
974 double width floating point constants by loading the two halves of the
975 value into the two single width floating point registers that make up
976 the double width register. By default @samp{--construct-floats} is
977 selected, allowing construction of these floating point constants.
980 @item --emulation=@var{name}
981 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
982 for some other target, in all respects, including output format (choosing
983 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
984 debugging information or store symbol table information, and default
985 endianness. The available configuration names are: @samp{mipsecoff},
986 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
987 @samp{mipsbelf}. The first two do not alter the default endianness from that
988 of the primary target for which the assembler was configured; the others change
989 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
990 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
991 selection in any case.
993 This option is currently supported only when the primary target
994 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
995 Furthermore, the primary target or others specified with
996 @samp{--enable-targets=@dots{}} at configuration time must include support for
997 the other format, if both are to be available. For example, the Irix 5
998 configuration includes support for both.
1000 Eventually, this option will support more configurations, with more
1001 fine-grained control over the assembler's behavior, and will be supported for
1005 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1012 Control how to deal with multiplication overflow and division by zero.
1013 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1014 (and only work for Instruction Set Architecture level 2 and higher);
1015 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1019 When this option is used, @command{@value{AS}} will issue a warning every
1020 time it generates a nop instruction from a macro.
1025 The following options are available when @value{AS} is configured for
1031 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1032 The command line option @samp{-nojsri2bsr} can be used to disable it.
1036 Enable or disable the silicon filter behaviour. By default this is disabled.
1037 The default can be overridden by the @samp{-sifilter} command line option.
1040 Alter jump instructions for long displacements.
1042 @item -mcpu=[210|340]
1043 Select the cpu type on the target hardware. This controls which instructions
1047 Assemble for a big endian target.
1050 Assemble for a little endian target.
1056 See the info pages for documentation of the MMIX-specific options.
1060 The following options are available when @value{AS} is configured for
1061 an Xtensa processor.
1064 @item --text-section-literals | --no-text-section-literals
1065 With @option{--text-@-section-@-literals}, literal pools are interspersed
1066 in the text section. The default is
1067 @option{--no-@-text-@-section-@-literals}, which places literals in a
1068 separate section in the output file. These options only affect literals
1069 referenced via PC-relative @code{L32R} instructions; literals for
1070 absolute mode @code{L32R} instructions are handled separately.
1072 @item --absolute-literals | --no-absolute-literals
1073 Indicate to the assembler whether @code{L32R} instructions use absolute
1074 or PC-relative addressing. The default is to assume absolute addressing
1075 if the Xtensa processor includes the absolute @code{L32R} addressing
1076 option. Otherwise, only the PC-relative @code{L32R} mode can be used.
1078 @item --target-align | --no-target-align
1079 Enable or disable automatic alignment to reduce branch penalties at the
1080 expense of some code density. The default is @option{--target-@-align}.
1082 @item --longcalls | --no-longcalls
1083 Enable or disable transformation of call instructions to allow calls
1084 across a greater range of addresses. The default is
1085 @option{--no-@-longcalls}.
1087 @item --transform | --no-transform
1088 Enable or disable all assembler transformations of Xtensa instructions.
1089 The default is @option{--transform};
1090 @option{--no-transform} should be used only in the rare cases when the
1091 instructions must be exactly as specified in the assembly source.
1098 * Manual:: Structure of this Manual
1099 * GNU Assembler:: The GNU Assembler
1100 * Object Formats:: Object File Formats
1101 * Command Line:: Command Line
1102 * Input Files:: Input Files
1103 * Object:: Output (Object) File
1104 * Errors:: Error and Warning Messages
1108 @section Structure of this Manual
1110 @cindex manual, structure and purpose
1111 This manual is intended to describe what you need to know to use
1112 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1113 notation for symbols, constants, and expressions; the directives that
1114 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1117 We also cover special features in the @value{TARGET}
1118 configuration of @command{@value{AS}}, including assembler directives.
1121 This manual also describes some of the machine-dependent features of
1122 various flavors of the assembler.
1125 @cindex machine instructions (not covered)
1126 On the other hand, this manual is @emph{not} intended as an introduction
1127 to programming in assembly language---let alone programming in general!
1128 In a similar vein, we make no attempt to introduce the machine
1129 architecture; we do @emph{not} describe the instruction set, standard
1130 mnemonics, registers or addressing modes that are standard to a
1131 particular architecture.
1133 You may want to consult the manufacturer's
1134 machine architecture manual for this information.
1138 For information on the H8/300 machine instruction set, see @cite{H8/300
1139 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1140 Programming Manual} (Renesas).
1143 For information on the H8/500 machine instruction set, see @cite{H8/500
1144 Series Programming Manual} (Renesas M21T001).
1147 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1148 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1149 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1150 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1153 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1157 @c I think this is premature---doc@cygnus.com, 17jan1991
1159 Throughout this manual, we assume that you are running @dfn{GNU},
1160 the portable operating system from the @dfn{Free Software
1161 Foundation, Inc.}. This restricts our attention to certain kinds of
1162 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1163 once this assumption is granted examples and definitions need less
1166 @command{@value{AS}} is part of a team of programs that turn a high-level
1167 human-readable series of instructions into a low-level
1168 computer-readable series of instructions. Different versions of
1169 @command{@value{AS}} are used for different kinds of computer.
1172 @c There used to be a section "Terminology" here, which defined
1173 @c "contents", "byte", "word", and "long". Defining "word" to any
1174 @c particular size is confusing when the .word directive may generate 16
1175 @c bits on one machine and 32 bits on another; in general, for the user
1176 @c version of this manual, none of these terms seem essential to define.
1177 @c They were used very little even in the former draft of the manual;
1178 @c this draft makes an effort to avoid them (except in names of
1182 @section The GNU Assembler
1184 @c man begin DESCRIPTION
1186 @sc{gnu} @command{as} is really a family of assemblers.
1188 This manual describes @command{@value{AS}}, a member of that family which is
1189 configured for the @value{TARGET} architectures.
1191 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1192 should find a fairly similar environment when you use it on another
1193 architecture. Each version has much in common with the others,
1194 including object file formats, most assembler directives (often called
1195 @dfn{pseudo-ops}) and assembler syntax.@refill
1197 @cindex purpose of @sc{gnu} assembler
1198 @command{@value{AS}} is primarily intended to assemble the output of the
1199 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1200 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1201 assemble correctly everything that other assemblers for the same
1202 machine would assemble.
1204 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1207 @c This remark should appear in generic version of manual; assumption
1208 @c here is that generic version sets M680x0.
1209 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1210 assembler for the same architecture; for example, we know of several
1211 incompatible versions of 680x0 assembly language syntax.
1216 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1217 program in one pass of the source file. This has a subtle impact on the
1218 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1220 @node Object Formats
1221 @section Object File Formats
1223 @cindex object file format
1224 The @sc{gnu} assembler can be configured to produce several alternative
1225 object file formats. For the most part, this does not affect how you
1226 write assembly language programs; but directives for debugging symbols
1227 are typically different in different file formats. @xref{Symbol
1228 Attributes,,Symbol Attributes}.
1231 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1232 @value{OBJ-NAME} format object files.
1234 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1236 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1237 @code{a.out} or COFF format object files.
1240 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1241 @code{b.out} or COFF format object files.
1244 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1245 SOM or ELF format object files.
1250 @section Command Line
1252 @cindex command line conventions
1254 After the program name @command{@value{AS}}, the command line may contain
1255 options and file names. Options may appear in any order, and may be
1256 before, after, or between file names. The order of file names is
1259 @cindex standard input, as input file
1261 @file{--} (two hyphens) by itself names the standard input file
1262 explicitly, as one of the files for @command{@value{AS}} to assemble.
1264 @cindex options, command line
1265 Except for @samp{--} any command line argument that begins with a
1266 hyphen (@samp{-}) is an option. Each option changes the behavior of
1267 @command{@value{AS}}. No option changes the way another option works. An
1268 option is a @samp{-} followed by one or more letters; the case of
1269 the letter is important. All options are optional.
1271 Some options expect exactly one file name to follow them. The file
1272 name may either immediately follow the option's letter (compatible
1273 with older assemblers) or it may be the next command argument (@sc{gnu}
1274 standard). These two command lines are equivalent:
1277 @value{AS} -o my-object-file.o mumble.s
1278 @value{AS} -omy-object-file.o mumble.s
1282 @section Input Files
1285 @cindex source program
1286 @cindex files, input
1287 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1288 describe the program input to one run of @command{@value{AS}}. The program may
1289 be in one or more files; how the source is partitioned into files
1290 doesn't change the meaning of the source.
1292 @c I added "con" prefix to "catenation" just to prove I can overcome my
1293 @c APL training... doc@cygnus.com
1294 The source program is a concatenation of the text in all the files, in the
1297 @c man begin DESCRIPTION
1298 Each time you run @command{@value{AS}} it assembles exactly one source
1299 program. The source program is made up of one or more files.
1300 (The standard input is also a file.)
1302 You give @command{@value{AS}} a command line that has zero or more input file
1303 names. The input files are read (from left file name to right). A
1304 command line argument (in any position) that has no special meaning
1305 is taken to be an input file name.
1307 If you give @command{@value{AS}} no file names it attempts to read one input file
1308 from the @command{@value{AS}} standard input, which is normally your terminal. You
1309 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1312 Use @samp{--} if you need to explicitly name the standard input file
1313 in your command line.
1315 If the source is empty, @command{@value{AS}} produces a small, empty object
1320 @subheading Filenames and Line-numbers
1322 @cindex input file linenumbers
1323 @cindex line numbers, in input files
1324 There are two ways of locating a line in the input file (or files) and
1325 either may be used in reporting error messages. One way refers to a line
1326 number in a physical file; the other refers to a line number in a
1327 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1329 @dfn{Physical files} are those files named in the command line given
1330 to @command{@value{AS}}.
1332 @dfn{Logical files} are simply names declared explicitly by assembler
1333 directives; they bear no relation to physical files. Logical file names help
1334 error messages reflect the original source file, when @command{@value{AS}} source
1335 is itself synthesized from other files. @command{@value{AS}} understands the
1336 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1337 @ref{File,,@code{.file}}.
1340 @section Output (Object) File
1346 Every time you run @command{@value{AS}} it produces an output file, which is
1347 your assembly language program translated into numbers. This file
1348 is the object file. Its default name is
1356 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1358 You can give it another name by using the @option{-o} option. Conventionally,
1359 object file names end with @file{.o}. The default name is used for historical
1360 reasons: older assemblers were capable of assembling self-contained programs
1361 directly into a runnable program. (For some formats, this isn't currently
1362 possible, but it can be done for the @code{a.out} format.)
1366 The object file is meant for input to the linker @code{@value{LD}}. It contains
1367 assembled program code, information to help @code{@value{LD}} integrate
1368 the assembled program into a runnable file, and (optionally) symbolic
1369 information for the debugger.
1371 @c link above to some info file(s) like the description of a.out.
1372 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1375 @section Error and Warning Messages
1377 @c man begin DESCRIPTION
1379 @cindex error messages
1380 @cindex warning messages
1381 @cindex messages from assembler
1382 @command{@value{AS}} may write warnings and error messages to the standard error
1383 file (usually your terminal). This should not happen when a compiler
1384 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1385 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1386 grave problem that stops the assembly.
1390 @cindex format of warning messages
1391 Warning messages have the format
1394 file_name:@b{NNN}:Warning Message Text
1398 @cindex line numbers, in warnings/errors
1399 (where @b{NNN} is a line number). If a logical file name has been given
1400 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1401 the current input file is used. If a logical line number was given
1403 (@pxref{Line,,@code{.line}})
1407 (@pxref{Line,,@code{.line}})
1410 (@pxref{Ln,,@code{.ln}})
1413 then it is used to calculate the number printed,
1414 otherwise the actual line in the current source file is printed. The
1415 message text is intended to be self explanatory (in the grand Unix
1418 @cindex format of error messages
1419 Error messages have the format
1421 file_name:@b{NNN}:FATAL:Error Message Text
1423 The file name and line number are derived as for warning
1424 messages. The actual message text may be rather less explanatory
1425 because many of them aren't supposed to happen.
1428 @chapter Command-Line Options
1430 @cindex options, all versions of assembler
1431 This chapter describes command-line options available in @emph{all}
1432 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1434 to the @value{TARGET} target.
1437 to particular machine architectures.
1440 @c man begin DESCRIPTION
1442 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
1443 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1444 The assembler arguments must be separated from each other (and the @samp{-Wa})
1445 by commas. For example:
1448 gcc -c -g -O -Wa,-alh,-L file.c
1452 This passes two options to the assembler: @samp{-alh} (emit a listing to
1453 standard output with high-level and assembly source) and @samp{-L} (retain
1454 local symbols in the symbol table).
1456 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1457 command-line options are automatically passed to the assembler by the compiler.
1458 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1459 precisely what options it passes to each compilation pass, including the
1465 * a:: -a[cdhlns] enable listings
1466 * alternate:: --alternate enable alternate macro syntax
1467 * D:: -D for compatibility
1468 * f:: -f to work faster
1469 * I:: -I for .include search path
1470 @ifclear DIFF-TBL-KLUGE
1471 * K:: -K for compatibility
1473 @ifset DIFF-TBL-KLUGE
1474 * K:: -K for difference tables
1477 * L:: -L to retain local labels
1478 * listing:: --listing-XXX to configure listing output
1479 * M:: -M or --mri to assemble in MRI compatibility mode
1480 * MD:: --MD for dependency tracking
1481 * o:: -o to name the object file
1482 * R:: -R to join data and text sections
1483 * statistics:: --statistics to see statistics about assembly
1484 * traditional-format:: --traditional-format for compatible output
1485 * v:: -v to announce version
1486 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1487 * Z:: -Z to make object file even after errors
1491 @section Enable Listings: @option{-a[cdhlns]}
1500 @cindex listings, enabling
1501 @cindex assembly listings, enabling
1503 These options enable listing output from the assembler. By itself,
1504 @samp{-a} requests high-level, assembly, and symbols listing.
1505 You can use other letters to select specific options for the list:
1506 @samp{-ah} requests a high-level language listing,
1507 @samp{-al} requests an output-program assembly listing, and
1508 @samp{-as} requests a symbol table listing.
1509 High-level listings require that a compiler debugging option like
1510 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1513 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1514 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1515 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1516 omitted from the listing.
1518 Use the @samp{-ad} option to omit debugging directives from the
1521 Once you have specified one of these options, you can further control
1522 listing output and its appearance using the directives @code{.list},
1523 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1525 The @samp{-an} option turns off all forms processing.
1526 If you do not request listing output with one of the @samp{-a} options, the
1527 listing-control directives have no effect.
1529 The letters after @samp{-a} may be combined into one option,
1530 @emph{e.g.}, @samp{-aln}.
1532 Note if the assembler source is coming from the standard input (eg because it
1533 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1534 is being used) then the listing will not contain any comments or preprocessor
1535 directives. This is because the listing code buffers input source lines from
1536 stdin only after they have been preprocessed by the assembler. This reduces
1537 memory usage and makes the code more efficient.
1540 @section @option{--alternate}
1543 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
1546 @section @option{-D}
1549 This option has no effect whatsoever, but it is accepted to make it more
1550 likely that scripts written for other assemblers also work with
1551 @command{@value{AS}}.
1554 @section Work Faster: @option{-f}
1557 @cindex trusted compiler
1558 @cindex faster processing (@option{-f})
1559 @samp{-f} should only be used when assembling programs written by a
1560 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1561 and comment preprocessing on
1562 the input file(s) before assembling them. @xref{Preprocessing,
1566 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1567 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1572 @section @code{.include} Search Path: @option{-I} @var{path}
1574 @kindex -I @var{path}
1575 @cindex paths for @code{.include}
1576 @cindex search path for @code{.include}
1577 @cindex @code{include} directive search path
1578 Use this option to add a @var{path} to the list of directories
1579 @command{@value{AS}} searches for files specified in @code{.include}
1580 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1581 many times as necessary to include a variety of paths. The current
1582 working directory is always searched first; after that, @command{@value{AS}}
1583 searches any @samp{-I} directories in the same order as they were
1584 specified (left to right) on the command line.
1587 @section Difference Tables: @option{-K}
1590 @ifclear DIFF-TBL-KLUGE
1591 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1592 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1593 where it can be used to warn when the assembler alters the machine code
1594 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1595 family does not have the addressing limitations that sometimes lead to this
1596 alteration on other platforms.
1599 @ifset DIFF-TBL-KLUGE
1600 @cindex difference tables, warning
1601 @cindex warning for altered difference tables
1602 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1603 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1604 You can use the @samp{-K} option if you want a warning issued when this
1609 @section Include Local Labels: @option{-L}
1612 @cindex local labels, retaining in output
1613 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1614 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1615 debugging, because they are intended for the use of programs (like
1616 compilers) that compose assembler programs, not for your notice.
1617 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1618 normally debug with them.
1620 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1621 in the object file. Usually if you do this you also tell the linker
1622 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1624 By default, a local label is any label beginning with @samp{L}, but each
1625 target is allowed to redefine the local label prefix.
1627 On the HPPA local labels begin with @samp{L$}.
1631 @section Configuring listing output: @option{--listing}
1633 The listing feature of the assembler can be enabled via the command line switch
1634 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1635 hex dump of the corresponding locations in the output object file, and displays
1636 them as a listing file. The format of this listing can be controlled by pseudo
1637 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1638 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1641 @item --listing-lhs-width=@samp{number}
1642 @kindex --listing-lhs-width
1643 @cindex Width of first line disassembly output
1644 Sets the maximum width, in words, of the first line of the hex byte dump. This
1645 dump appears on the left hand side of the listing output.
1647 @item --listing-lhs-width2=@samp{number}
1648 @kindex --listing-lhs-width2
1649 @cindex Width of continuation lines of disassembly output
1650 Sets the maximum width, in words, of any further lines of the hex byte dump for
1651 a given input source line. If this value is not specified, it defaults to being
1652 the same as the value specified for @samp{--listing-lhs-width}. If neither
1653 switch is used the default is to one.
1655 @item --listing-rhs-width=@samp{number}
1656 @kindex --listing-rhs-width
1657 @cindex Width of source line output
1658 Sets the maximum width, in characters, of the source line that is displayed
1659 alongside the hex dump. The default value for this parameter is 100. The
1660 source line is displayed on the right hand side of the listing output.
1662 @item --listing-cont-lines=@samp{number}
1663 @kindex --listing-cont-lines
1664 @cindex Maximum number of continuation lines
1665 Sets the maximum number of continuation lines of hex dump that will be
1666 displayed for a given single line of source input. The default value is 4.
1670 @section Assemble in MRI Compatibility Mode: @option{-M}
1673 @cindex MRI compatibility mode
1674 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1675 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1676 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1677 configured target) assembler from Microtec Research. The exact nature of the
1678 MRI syntax will not be documented here; see the MRI manuals for more
1679 information. Note in particular that the handling of macros and macro
1680 arguments is somewhat different. The purpose of this option is to permit
1681 assembling existing MRI assembler code using @command{@value{AS}}.
1683 The MRI compatibility is not complete. Certain operations of the MRI assembler
1684 depend upon its object file format, and can not be supported using other object
1685 file formats. Supporting these would require enhancing each object file format
1686 individually. These are:
1689 @item global symbols in common section
1691 The m68k MRI assembler supports common sections which are merged by the linker.
1692 Other object file formats do not support this. @command{@value{AS}} handles
1693 common sections by treating them as a single common symbol. It permits local
1694 symbols to be defined within a common section, but it can not support global
1695 symbols, since it has no way to describe them.
1697 @item complex relocations
1699 The MRI assemblers support relocations against a negated section address, and
1700 relocations which combine the start addresses of two or more sections. These
1701 are not support by other object file formats.
1703 @item @code{END} pseudo-op specifying start address
1705 The MRI @code{END} pseudo-op permits the specification of a start address.
1706 This is not supported by other object file formats. The start address may
1707 instead be specified using the @option{-e} option to the linker, or in a linker
1710 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1712 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1713 name to the output file. This is not supported by other object file formats.
1715 @item @code{ORG} pseudo-op
1717 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1718 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1719 which changes the location within the current section. Absolute sections are
1720 not supported by other object file formats. The address of a section may be
1721 assigned within a linker script.
1724 There are some other features of the MRI assembler which are not supported by
1725 @command{@value{AS}}, typically either because they are difficult or because they
1726 seem of little consequence. Some of these may be supported in future releases.
1730 @item EBCDIC strings
1732 EBCDIC strings are not supported.
1734 @item packed binary coded decimal
1736 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1737 and @code{DCB.P} pseudo-ops are not supported.
1739 @item @code{FEQU} pseudo-op
1741 The m68k @code{FEQU} pseudo-op is not supported.
1743 @item @code{NOOBJ} pseudo-op
1745 The m68k @code{NOOBJ} pseudo-op is not supported.
1747 @item @code{OPT} branch control options
1749 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1750 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1751 relaxes all branches, whether forward or backward, to an appropriate size, so
1752 these options serve no purpose.
1754 @item @code{OPT} list control options
1756 The following m68k @code{OPT} list control options are ignored: @code{C},
1757 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1758 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1760 @item other @code{OPT} options
1762 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1763 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1765 @item @code{OPT} @code{D} option is default
1767 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1768 @code{OPT NOD} may be used to turn it off.
1770 @item @code{XREF} pseudo-op.
1772 The m68k @code{XREF} pseudo-op is ignored.
1774 @item @code{.debug} pseudo-op
1776 The i960 @code{.debug} pseudo-op is not supported.
1778 @item @code{.extended} pseudo-op
1780 The i960 @code{.extended} pseudo-op is not supported.
1782 @item @code{.list} pseudo-op.
1784 The various options of the i960 @code{.list} pseudo-op are not supported.
1786 @item @code{.optimize} pseudo-op
1788 The i960 @code{.optimize} pseudo-op is not supported.
1790 @item @code{.output} pseudo-op
1792 The i960 @code{.output} pseudo-op is not supported.
1794 @item @code{.setreal} pseudo-op
1796 The i960 @code{.setreal} pseudo-op is not supported.
1801 @section Dependency Tracking: @option{--MD}
1804 @cindex dependency tracking
1807 @command{@value{AS}} can generate a dependency file for the file it creates. This
1808 file consists of a single rule suitable for @code{make} describing the
1809 dependencies of the main source file.
1811 The rule is written to the file named in its argument.
1813 This feature is used in the automatic updating of makefiles.
1816 @section Name the Object File: @option{-o}
1819 @cindex naming object file
1820 @cindex object file name
1821 There is always one object file output when you run @command{@value{AS}}. By
1822 default it has the name
1825 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1839 You use this option (which takes exactly one filename) to give the
1840 object file a different name.
1842 Whatever the object file is called, @command{@value{AS}} overwrites any
1843 existing file of the same name.
1846 @section Join Data and Text Sections: @option{-R}
1849 @cindex data and text sections, joining
1850 @cindex text and data sections, joining
1851 @cindex joining text and data sections
1852 @cindex merging text and data sections
1853 @option{-R} tells @command{@value{AS}} to write the object file as if all
1854 data-section data lives in the text section. This is only done at
1855 the very last moment: your binary data are the same, but data
1856 section parts are relocated differently. The data section part of
1857 your object file is zero bytes long because all its bytes are
1858 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1860 When you specify @option{-R} it would be possible to generate shorter
1861 address displacements (because we do not have to cross between text and
1862 data section). We refrain from doing this simply for compatibility with
1863 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1866 When @command{@value{AS}} is configured for COFF or ELF output,
1867 this option is only useful if you use sections named @samp{.text} and
1872 @option{-R} is not supported for any of the HPPA targets. Using
1873 @option{-R} generates a warning from @command{@value{AS}}.
1877 @section Display Assembly Statistics: @option{--statistics}
1879 @kindex --statistics
1880 @cindex statistics, about assembly
1881 @cindex time, total for assembly
1882 @cindex space used, maximum for assembly
1883 Use @samp{--statistics} to display two statistics about the resources used by
1884 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1885 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1888 @node traditional-format
1889 @section Compatible Output: @option{--traditional-format}
1891 @kindex --traditional-format
1892 For some targets, the output of @command{@value{AS}} is different in some ways
1893 from the output of some existing assembler. This switch requests
1894 @command{@value{AS}} to use the traditional format instead.
1896 For example, it disables the exception frame optimizations which
1897 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1900 @section Announce Version: @option{-v}
1904 @cindex assembler version
1905 @cindex version of assembler
1906 You can find out what version of as is running by including the
1907 option @samp{-v} (which you can also spell as @samp{-version}) on the
1911 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1913 @command{@value{AS}} should never give a warning or error message when
1914 assembling compiler output. But programs written by people often
1915 cause @command{@value{AS}} to give a warning that a particular assumption was
1916 made. All such warnings are directed to the standard error file.
1920 @cindex suppressing warnings
1921 @cindex warnings, suppressing
1922 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1923 This only affects the warning messages: it does not change any particular of
1924 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1927 @kindex --fatal-warnings
1928 @cindex errors, caused by warnings
1929 @cindex warnings, causing error
1930 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1931 files that generate warnings to be in error.
1934 @cindex warnings, switching on
1935 You can switch these options off again by specifying @option{--warn}, which
1936 causes warnings to be output as usual.
1939 @section Generate Object File in Spite of Errors: @option{-Z}
1940 @cindex object file, after errors
1941 @cindex errors, continuing after
1942 After an error message, @command{@value{AS}} normally produces no output. If for
1943 some reason you are interested in object file output even after
1944 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1945 option. If there are any errors, @command{@value{AS}} continues anyways, and
1946 writes an object file after a final warning message of the form @samp{@var{n}
1947 errors, @var{m} warnings, generating bad object file.}
1952 @cindex machine-independent syntax
1953 @cindex syntax, machine-independent
1954 This chapter describes the machine-independent syntax allowed in a
1955 source file. @command{@value{AS}} syntax is similar to what many other
1956 assemblers use; it is inspired by the BSD 4.2
1961 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1965 * Preprocessing:: Preprocessing
1966 * Whitespace:: Whitespace
1967 * Comments:: Comments
1968 * Symbol Intro:: Symbols
1969 * Statements:: Statements
1970 * Constants:: Constants
1974 @section Preprocessing
1976 @cindex preprocessing
1977 The @command{@value{AS}} internal preprocessor:
1979 @cindex whitespace, removed by preprocessor
1981 adjusts and removes extra whitespace. It leaves one space or tab before
1982 the keywords on a line, and turns any other whitespace on the line into
1985 @cindex comments, removed by preprocessor
1987 removes all comments, replacing them with a single space, or an
1988 appropriate number of newlines.
1990 @cindex constants, converted by preprocessor
1992 converts character constants into the appropriate numeric values.
1995 It does not do macro processing, include file handling, or
1996 anything else you may get from your C compiler's preprocessor. You can
1997 do include file processing with the @code{.include} directive
1998 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1999 to get other ``CPP'' style preprocessing by giving the input file a
2000 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
2001 Output, gcc.info, Using GNU CC}.
2003 Excess whitespace, comments, and character constants
2004 cannot be used in the portions of the input text that are not
2007 @cindex turning preprocessing on and off
2008 @cindex preprocessing, turning on and off
2011 If the first line of an input file is @code{#NO_APP} or if you use the
2012 @samp{-f} option, whitespace and comments are not removed from the input file.
2013 Within an input file, you can ask for whitespace and comment removal in
2014 specific portions of the by putting a line that says @code{#APP} before the
2015 text that may contain whitespace or comments, and putting a line that says
2016 @code{#NO_APP} after this text. This feature is mainly intend to support
2017 @code{asm} statements in compilers whose output is otherwise free of comments
2024 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2025 Whitespace is used to separate symbols, and to make programs neater for
2026 people to read. Unless within character constants
2027 (@pxref{Characters,,Character Constants}), any whitespace means the same
2028 as exactly one space.
2034 There are two ways of rendering comments to @command{@value{AS}}. In both
2035 cases the comment is equivalent to one space.
2037 Anything from @samp{/*} through the next @samp{*/} is a comment.
2038 This means you may not nest these comments.
2042 The only way to include a newline ('\n') in a comment
2043 is to use this sort of comment.
2046 /* This sort of comment does not nest. */
2049 @cindex line comment character
2050 Anything from the @dfn{line comment} character to the next newline
2051 is considered a comment and is ignored. The line comment character is
2053 @samp{;} for the AMD 29K family;
2056 @samp{;} on the ARC;
2059 @samp{@@} on the ARM;
2062 @samp{;} for the H8/300 family;
2065 @samp{!} for the H8/500 family;
2068 @samp{;} for the HPPA;
2071 @samp{#} on the i386 and x86-64;
2074 @samp{#} on the i960;
2077 @samp{;} for the PDP-11;
2080 @samp{;} for picoJava;
2083 @samp{#} for Motorola PowerPC;
2086 @samp{!} for the Renesas / SuperH SH;
2089 @samp{!} on the SPARC;
2092 @samp{#} on the ip2k;
2095 @samp{#} on the m32r;
2098 @samp{|} on the 680x0;
2101 @samp{#} on the 68HC11 and 68HC12;
2104 @samp{;} on the M880x0;
2107 @samp{#} on the Vax;
2110 @samp{!} for the Z8000;
2113 @samp{#} on the V850;
2116 @samp{#} for Xtensa systems;
2118 see @ref{Machine Dependencies}. @refill
2119 @c FIXME What about i860?
2122 On some machines there are two different line comment characters. One
2123 character only begins a comment if it is the first non-whitespace character on
2124 a line, while the other always begins a comment.
2128 The V850 assembler also supports a double dash as starting a comment that
2129 extends to the end of the line.
2135 @cindex lines starting with @code{#}
2136 @cindex logical line numbers
2137 To be compatible with past assemblers, lines that begin with @samp{#} have a
2138 special interpretation. Following the @samp{#} should be an absolute
2139 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2140 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
2141 new logical file name. The rest of the line, if any, should be whitespace.
2143 If the first non-whitespace characters on the line are not numeric,
2144 the line is ignored. (Just like a comment.)
2147 # This is an ordinary comment.
2148 # 42-6 "new_file_name" # New logical file name
2149 # This is logical line # 36.
2151 This feature is deprecated, and may disappear from future versions
2152 of @command{@value{AS}}.
2157 @cindex characters used in symbols
2158 @ifclear SPECIAL-SYMS
2159 A @dfn{symbol} is one or more characters chosen from the set of all
2160 letters (both upper and lower case), digits and the three characters
2166 A @dfn{symbol} is one or more characters chosen from the set of all
2167 letters (both upper and lower case), digits and the three characters
2168 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2174 On most machines, you can also use @code{$} in symbol names; exceptions
2175 are noted in @ref{Machine Dependencies}.
2177 No symbol may begin with a digit. Case is significant.
2178 There is no length limit: all characters are significant. Symbols are
2179 delimited by characters not in that set, or by the beginning of a file
2180 (since the source program must end with a newline, the end of a file is
2181 not a possible symbol delimiter). @xref{Symbols}.
2182 @cindex length of symbols
2187 @cindex statements, structure of
2188 @cindex line separator character
2189 @cindex statement separator character
2191 @ifclear abnormal-separator
2192 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2193 semicolon (@samp{;}). The newline or semicolon is considered part of
2194 the preceding statement. Newlines and semicolons within character
2195 constants are an exception: they do not end statements.
2197 @ifset abnormal-separator
2199 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2200 sign (@samp{@@}). The newline or at sign is considered part of the
2201 preceding statement. Newlines and at signs within character constants
2202 are an exception: they do not end statements.
2205 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2206 point (@samp{!}). The newline or exclamation point is considered part of the
2207 preceding statement. Newlines and exclamation points within character
2208 constants are an exception: they do not end statements.
2211 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2212 H8/300) a dollar sign (@samp{$}); or (for the
2215 (@samp{;}). The newline or separator character is considered part of
2216 the preceding statement. Newlines and separators within character
2217 constants are an exception: they do not end statements.
2222 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2223 separator character. (The line separator is usually @samp{;}, unless
2224 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2225 newline or separator character is considered part of the preceding
2226 statement. Newlines and separators within character constants are an
2227 exception: they do not end statements.
2230 @cindex newline, required at file end
2231 @cindex EOF, newline must precede
2232 It is an error to end any statement with end-of-file: the last
2233 character of any input file should be a newline.@refill
2235 An empty statement is allowed, and may include whitespace. It is ignored.
2237 @cindex instructions and directives
2238 @cindex directives and instructions
2239 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2240 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2242 A statement begins with zero or more labels, optionally followed by a
2243 key symbol which determines what kind of statement it is. The key
2244 symbol determines the syntax of the rest of the statement. If the
2245 symbol begins with a dot @samp{.} then the statement is an assembler
2246 directive: typically valid for any computer. If the symbol begins with
2247 a letter the statement is an assembly language @dfn{instruction}: it
2248 assembles into a machine language instruction.
2250 Different versions of @command{@value{AS}} for different computers
2251 recognize different instructions. In fact, the same symbol may
2252 represent a different instruction in a different computer's assembly
2256 @cindex @code{:} (label)
2257 @cindex label (@code{:})
2258 A label is a symbol immediately followed by a colon (@code{:}).
2259 Whitespace before a label or after a colon is permitted, but you may not
2260 have whitespace between a label's symbol and its colon. @xref{Labels}.
2263 For HPPA targets, labels need not be immediately followed by a colon, but
2264 the definition of a label must begin in column zero. This also implies that
2265 only one label may be defined on each line.
2269 label: .directive followed by something
2270 another_label: # This is an empty statement.
2271 instruction operand_1, operand_2, @dots{}
2278 A constant is a number, written so that its value is known by
2279 inspection, without knowing any context. Like this:
2282 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2283 .ascii "Ring the bell\7" # A string constant.
2284 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2285 .float 0f-314159265358979323846264338327\
2286 95028841971.693993751E-40 # - pi, a flonum.
2291 * Characters:: Character Constants
2292 * Numbers:: Number Constants
2296 @subsection Character Constants
2298 @cindex character constants
2299 @cindex constants, character
2300 There are two kinds of character constants. A @dfn{character} stands
2301 for one character in one byte and its value may be used in
2302 numeric expressions. String constants (properly called string
2303 @emph{literals}) are potentially many bytes and their values may not be
2304 used in arithmetic expressions.
2308 * Chars:: Characters
2312 @subsubsection Strings
2314 @cindex string constants
2315 @cindex constants, string
2316 A @dfn{string} is written between double-quotes. It may contain
2317 double-quotes or null characters. The way to get special characters
2318 into a string is to @dfn{escape} these characters: precede them with
2319 a backslash @samp{\} character. For example @samp{\\} represents
2320 one backslash: the first @code{\} is an escape which tells
2321 @command{@value{AS}} to interpret the second character literally as a backslash
2322 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2323 escape character). The complete list of escapes follows.
2325 @cindex escape codes, character
2326 @cindex character escape codes
2329 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2331 @cindex @code{\b} (backspace character)
2332 @cindex backspace (@code{\b})
2334 Mnemonic for backspace; for ASCII this is octal code 010.
2337 @c Mnemonic for EOText; for ASCII this is octal code 004.
2339 @cindex @code{\f} (formfeed character)
2340 @cindex formfeed (@code{\f})
2342 Mnemonic for FormFeed; for ASCII this is octal code 014.
2344 @cindex @code{\n} (newline character)
2345 @cindex newline (@code{\n})
2347 Mnemonic for newline; for ASCII this is octal code 012.
2350 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2352 @cindex @code{\r} (carriage return character)
2353 @cindex carriage return (@code{\r})
2355 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2358 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2359 @c other assemblers.
2361 @cindex @code{\t} (tab)
2362 @cindex tab (@code{\t})
2364 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2367 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2368 @c @item \x @var{digit} @var{digit} @var{digit}
2369 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2371 @cindex @code{\@var{ddd}} (octal character code)
2372 @cindex octal character code (@code{\@var{ddd}})
2373 @item \ @var{digit} @var{digit} @var{digit}
2374 An octal character code. The numeric code is 3 octal digits.
2375 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2376 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2378 @cindex @code{\@var{xd...}} (hex character code)
2379 @cindex hex character code (@code{\@var{xd...}})
2380 @item \@code{x} @var{hex-digits...}
2381 A hex character code. All trailing hex digits are combined. Either upper or
2382 lower case @code{x} works.
2384 @cindex @code{\\} (@samp{\} character)
2385 @cindex backslash (@code{\\})
2387 Represents one @samp{\} character.
2390 @c Represents one @samp{'} (accent acute) character.
2391 @c This is needed in single character literals
2392 @c (@xref{Characters,,Character Constants}.) to represent
2395 @cindex @code{\"} (doublequote character)
2396 @cindex doublequote (@code{\"})
2398 Represents one @samp{"} character. Needed in strings to represent
2399 this character, because an unescaped @samp{"} would end the string.
2401 @item \ @var{anything-else}
2402 Any other character when escaped by @kbd{\} gives a warning, but
2403 assembles as if the @samp{\} was not present. The idea is that if
2404 you used an escape sequence you clearly didn't want the literal
2405 interpretation of the following character. However @command{@value{AS}} has no
2406 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2407 code and warns you of the fact.
2410 Which characters are escapable, and what those escapes represent,
2411 varies widely among assemblers. The current set is what we think
2412 the BSD 4.2 assembler recognizes, and is a subset of what most C
2413 compilers recognize. If you are in doubt, do not use an escape
2417 @subsubsection Characters
2419 @cindex single character constant
2420 @cindex character, single
2421 @cindex constant, single character
2422 A single character may be written as a single quote immediately
2423 followed by that character. The same escapes apply to characters as
2424 to strings. So if you want to write the character backslash, you
2425 must write @kbd{'\\} where the first @code{\} escapes the second
2426 @code{\}. As you can see, the quote is an acute accent, not a
2427 grave accent. A newline
2429 @ifclear abnormal-separator
2430 (or semicolon @samp{;})
2432 @ifset abnormal-separator
2434 (or at sign @samp{@@})
2437 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2438 Renesas SH or H8/500)
2442 immediately following an acute accent is taken as a literal character
2443 and does not count as the end of a statement. The value of a character
2444 constant in a numeric expression is the machine's byte-wide code for
2445 that character. @command{@value{AS}} assumes your character code is ASCII:
2446 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2449 @subsection Number Constants
2451 @cindex constants, number
2452 @cindex number constants
2453 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2454 are stored in the target machine. @emph{Integers} are numbers that
2455 would fit into an @code{int} in the C language. @emph{Bignums} are
2456 integers, but they are stored in more than 32 bits. @emph{Flonums}
2457 are floating point numbers, described below.
2460 * Integers:: Integers
2465 * Bit Fields:: Bit Fields
2471 @subsubsection Integers
2473 @cindex constants, integer
2475 @cindex binary integers
2476 @cindex integers, binary
2477 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2478 the binary digits @samp{01}.
2480 @cindex octal integers
2481 @cindex integers, octal
2482 An octal integer is @samp{0} followed by zero or more of the octal
2483 digits (@samp{01234567}).
2485 @cindex decimal integers
2486 @cindex integers, decimal
2487 A decimal integer starts with a non-zero digit followed by zero or
2488 more digits (@samp{0123456789}).
2490 @cindex hexadecimal integers
2491 @cindex integers, hexadecimal
2492 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2493 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2495 Integers have the usual values. To denote a negative integer, use
2496 the prefix operator @samp{-} discussed under expressions
2497 (@pxref{Prefix Ops,,Prefix Operators}).
2500 @subsubsection Bignums
2503 @cindex constants, bignum
2504 A @dfn{bignum} has the same syntax and semantics as an integer
2505 except that the number (or its negative) takes more than 32 bits to
2506 represent in binary. The distinction is made because in some places
2507 integers are permitted while bignums are not.
2510 @subsubsection Flonums
2512 @cindex floating point numbers
2513 @cindex constants, floating point
2515 @cindex precision, floating point
2516 A @dfn{flonum} represents a floating point number. The translation is
2517 indirect: a decimal floating point number from the text is converted by
2518 @command{@value{AS}} to a generic binary floating point number of more than
2519 sufficient precision. This generic floating point number is converted
2520 to a particular computer's floating point format (or formats) by a
2521 portion of @command{@value{AS}} specialized to that computer.
2523 A flonum is written by writing (in order)
2528 (@samp{0} is optional on the HPPA.)
2532 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2534 @kbd{e} is recommended. Case is not important.
2536 @c FIXME: verify if flonum syntax really this vague for most cases
2537 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2538 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2541 On the H8/300, H8/500,
2542 Renesas / SuperH SH,
2543 and AMD 29K architectures, the letter must be
2544 one of the letters @samp{DFPRSX} (in upper or lower case).
2546 On the ARC, the letter must be one of the letters @samp{DFRS}
2547 (in upper or lower case).
2549 On the Intel 960 architecture, the letter must be
2550 one of the letters @samp{DFT} (in upper or lower case).
2552 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2556 One of the letters @samp{DFPRSX} (in upper or lower case).
2559 One of the letters @samp{DFRS} (in upper or lower case).
2562 One of the letters @samp{DFPRSX} (in upper or lower case).
2565 The letter @samp{E} (upper case only).
2568 One of the letters @samp{DFT} (in upper or lower case).
2573 An optional sign: either @samp{+} or @samp{-}.
2576 An optional @dfn{integer part}: zero or more decimal digits.
2579 An optional @dfn{fractional part}: @samp{.} followed by zero
2580 or more decimal digits.
2583 An optional exponent, consisting of:
2587 An @samp{E} or @samp{e}.
2588 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2589 @c principle this can perfectly well be different on different targets.
2591 Optional sign: either @samp{+} or @samp{-}.
2593 One or more decimal digits.
2598 At least one of the integer part or the fractional part must be
2599 present. The floating point number has the usual base-10 value.
2601 @command{@value{AS}} does all processing using integers. Flonums are computed
2602 independently of any floating point hardware in the computer running
2603 @command{@value{AS}}.
2607 @c Bit fields are written as a general facility but are also controlled
2608 @c by a conditional-compilation flag---which is as of now (21mar91)
2609 @c turned on only by the i960 config of GAS.
2611 @subsubsection Bit Fields
2614 @cindex constants, bit field
2615 You can also define numeric constants as @dfn{bit fields}.
2616 specify two numbers separated by a colon---
2618 @var{mask}:@var{value}
2621 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2624 The resulting number is then packed
2626 @c this conditional paren in case bit fields turned on elsewhere than 960
2627 (in host-dependent byte order)
2629 into a field whose width depends on which assembler directive has the
2630 bit-field as its argument. Overflow (a result from the bitwise and
2631 requiring more binary digits to represent) is not an error; instead,
2632 more constants are generated, of the specified width, beginning with the
2633 least significant digits.@refill
2635 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2636 @code{.short}, and @code{.word} accept bit-field arguments.
2641 @chapter Sections and Relocation
2646 * Secs Background:: Background
2647 * Ld Sections:: Linker Sections
2648 * As Sections:: Assembler Internal Sections
2649 * Sub-Sections:: Sub-Sections
2653 @node Secs Background
2656 Roughly, a section is a range of addresses, with no gaps; all data
2657 ``in'' those addresses is treated the same for some particular purpose.
2658 For example there may be a ``read only'' section.
2660 @cindex linker, and assembler
2661 @cindex assembler, and linker
2662 The linker @code{@value{LD}} reads many object files (partial programs) and
2663 combines their contents to form a runnable program. When @command{@value{AS}}
2664 emits an object file, the partial program is assumed to start at address 0.
2665 @code{@value{LD}} assigns the final addresses for the partial program, so that
2666 different partial programs do not overlap. This is actually an
2667 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2670 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2671 addresses. These blocks slide to their run-time addresses as rigid
2672 units; their length does not change and neither does the order of bytes
2673 within them. Such a rigid unit is called a @emph{section}. Assigning
2674 run-time addresses to sections is called @dfn{relocation}. It includes
2675 the task of adjusting mentions of object-file addresses so they refer to
2676 the proper run-time addresses.
2678 For the H8/300 and H8/500,
2679 and for the Renesas / SuperH SH,
2680 @command{@value{AS}} pads sections if needed to
2681 ensure they end on a word (sixteen bit) boundary.
2684 @cindex standard assembler sections
2685 An object file written by @command{@value{AS}} has at least three sections, any
2686 of which may be empty. These are named @dfn{text}, @dfn{data} and
2691 When it generates COFF or ELF output,
2693 @command{@value{AS}} can also generate whatever other named sections you specify
2694 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2695 If you do not use any directives that place output in the @samp{.text}
2696 or @samp{.data} sections, these sections still exist, but are empty.
2701 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2703 @command{@value{AS}} can also generate whatever other named sections you
2704 specify using the @samp{.space} and @samp{.subspace} directives. See
2705 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2706 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2707 assembler directives.
2710 Additionally, @command{@value{AS}} uses different names for the standard
2711 text, data, and bss sections when generating SOM output. Program text
2712 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2713 BSS into @samp{$BSS$}.
2717 Within the object file, the text section starts at address @code{0}, the
2718 data section follows, and the bss section follows the data section.
2721 When generating either SOM or ELF output files on the HPPA, the text
2722 section starts at address @code{0}, the data section at address
2723 @code{0x4000000}, and the bss section follows the data section.
2726 To let @code{@value{LD}} know which data changes when the sections are
2727 relocated, and how to change that data, @command{@value{AS}} also writes to the
2728 object file details of the relocation needed. To perform relocation
2729 @code{@value{LD}} must know, each time an address in the object
2733 Where in the object file is the beginning of this reference to
2736 How long (in bytes) is this reference?
2738 Which section does the address refer to? What is the numeric value of
2740 (@var{address}) @minus{} (@var{start-address of section})?
2743 Is the reference to an address ``Program-Counter relative''?
2746 @cindex addresses, format of
2747 @cindex section-relative addressing
2748 In fact, every address @command{@value{AS}} ever uses is expressed as
2750 (@var{section}) + (@var{offset into section})
2753 Further, most expressions @command{@value{AS}} computes have this section-relative
2756 (For some object formats, such as SOM for the HPPA, some expressions are
2757 symbol-relative instead.)
2760 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2761 @var{N} into section @var{secname}.''
2763 Apart from text, data and bss sections you need to know about the
2764 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2765 addresses in the absolute section remain unchanged. For example, address
2766 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2767 @code{@value{LD}}. Although the linker never arranges two partial programs'
2768 data sections with overlapping addresses after linking, @emph{by definition}
2769 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2770 part of a program is always the same address when the program is running as
2771 address @code{@{absolute@ 239@}} in any other part of the program.
2773 The idea of sections is extended to the @dfn{undefined} section. Any
2774 address whose section is unknown at assembly time is by definition
2775 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2776 Since numbers are always defined, the only way to generate an undefined
2777 address is to mention an undefined symbol. A reference to a named
2778 common block would be such a symbol: its value is unknown at assembly
2779 time so it has section @emph{undefined}.
2781 By analogy the word @emph{section} is used to describe groups of sections in
2782 the linked program. @code{@value{LD}} puts all partial programs' text
2783 sections in contiguous addresses in the linked program. It is
2784 customary to refer to the @emph{text section} of a program, meaning all
2785 the addresses of all partial programs' text sections. Likewise for
2786 data and bss sections.
2788 Some sections are manipulated by @code{@value{LD}}; others are invented for
2789 use of @command{@value{AS}} and have no meaning except during assembly.
2792 @section Linker Sections
2793 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2798 @cindex named sections
2799 @cindex sections, named
2800 @item named sections
2803 @cindex text section
2804 @cindex data section
2808 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2809 separate but equal sections. Anything you can say of one section is
2812 When the program is running, however, it is
2813 customary for the text section to be unalterable. The
2814 text section is often shared among processes: it contains
2815 instructions, constants and the like. The data section of a running
2816 program is usually alterable: for example, C variables would be stored
2817 in the data section.
2822 This section contains zeroed bytes when your program begins running. It
2823 is used to hold uninitialized variables or common storage. The length of
2824 each partial program's bss section is important, but because it starts
2825 out containing zeroed bytes there is no need to store explicit zero
2826 bytes in the object file. The bss section was invented to eliminate
2827 those explicit zeros from object files.
2829 @cindex absolute section
2830 @item absolute section
2831 Address 0 of this section is always ``relocated'' to runtime address 0.
2832 This is useful if you want to refer to an address that @code{@value{LD}} must
2833 not change when relocating. In this sense we speak of absolute
2834 addresses being ``unrelocatable'': they do not change during relocation.
2836 @cindex undefined section
2837 @item undefined section
2838 This ``section'' is a catch-all for address references to objects not in
2839 the preceding sections.
2840 @c FIXME: ref to some other doc on obj-file formats could go here.
2843 @cindex relocation example
2844 An idealized example of three relocatable sections follows.
2846 The example uses the traditional section names @samp{.text} and @samp{.data}.
2848 Memory addresses are on the horizontal axis.
2852 @c END TEXI2ROFF-KILL
2855 partial program # 1: |ttttt|dddd|00|
2862 partial program # 2: |TTT|DDD|000|
2865 +--+---+-----+--+----+---+-----+~~
2866 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2867 +--+---+-----+--+----+---+-----+~~
2869 addresses: 0 @dots{}
2876 \line{\it Partial program \#1: \hfil}
2877 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2878 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2880 \line{\it Partial program \#2: \hfil}
2881 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2882 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2884 \line{\it linked program: \hfil}
2885 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2886 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2887 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2888 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2890 \line{\it addresses: \hfil}
2894 @c END TEXI2ROFF-KILL
2897 @section Assembler Internal Sections
2899 @cindex internal assembler sections
2900 @cindex sections in messages, internal
2901 These sections are meant only for the internal use of @command{@value{AS}}. They
2902 have no meaning at run-time. You do not really need to know about these
2903 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2904 warning messages, so it might be helpful to have an idea of their
2905 meanings to @command{@value{AS}}. These sections are used to permit the
2906 value of every expression in your assembly language program to be a
2907 section-relative address.
2910 @cindex assembler internal logic error
2911 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2912 An internal assembler logic error has been found. This means there is a
2913 bug in the assembler.
2915 @cindex expr (internal section)
2917 The assembler stores complex expression internally as combinations of
2918 symbols. When it needs to represent an expression as a symbol, it puts
2919 it in the expr section.
2921 @c FIXME item transfer[t] vector preload
2922 @c FIXME item transfer[t] vector postload
2923 @c FIXME item register
2927 @section Sub-Sections
2929 @cindex numbered subsections
2930 @cindex grouping data
2936 fall into two sections: text and data.
2938 You may have separate groups of
2940 data in named sections
2944 data in named sections
2950 that you want to end up near to each other in the object file, even though they
2951 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2952 use @dfn{subsections} for this purpose. Within each section, there can be
2953 numbered subsections with values from 0 to 8192. Objects assembled into the
2954 same subsection go into the object file together with other objects in the same
2955 subsection. For example, a compiler might want to store constants in the text
2956 section, but might not want to have them interspersed with the program being
2957 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2958 section of code being output, and a @samp{.text 1} before each group of
2959 constants being output.
2961 Subsections are optional. If you do not use subsections, everything
2962 goes in subsection number zero.
2965 Each subsection is zero-padded up to a multiple of four bytes.
2966 (Subsections may be padded a different amount on different flavors
2967 of @command{@value{AS}}.)
2971 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2972 boundary (two bytes).
2973 The same is true on the Renesas SH.
2976 @c FIXME section padding (alignment)?
2977 @c Rich Pixley says padding here depends on target obj code format; that
2978 @c doesn't seem particularly useful to say without further elaboration,
2979 @c so for now I say nothing about it. If this is a generic BFD issue,
2980 @c these paragraphs might need to vanish from this manual, and be
2981 @c discussed in BFD chapter of binutils (or some such).
2984 On the AMD 29K family, no particular padding is added to section or
2985 subsection sizes; @value{AS} forces no alignment on this platform.
2989 Subsections appear in your object file in numeric order, lowest numbered
2990 to highest. (All this to be compatible with other people's assemblers.)
2991 The object file contains no representation of subsections; @code{@value{LD}} and
2992 other programs that manipulate object files see no trace of them.
2993 They just see all your text subsections as a text section, and all your
2994 data subsections as a data section.
2996 To specify which subsection you want subsequent statements assembled
2997 into, use a numeric argument to specify it, in a @samp{.text
2998 @var{expression}} or a @samp{.data @var{expression}} statement.
3001 When generating COFF output, you
3006 can also use an extra subsection
3007 argument with arbitrary named sections: @samp{.section @var{name},
3012 When generating ELF output, you
3017 can also use the @code{.subsection} directive (@pxref{SubSection})
3018 to specify a subsection: @samp{.subsection @var{expression}}.
3020 @var{Expression} should be an absolute expression.
3021 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
3022 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3023 begins in @code{text 0}. For instance:
3025 .text 0 # The default subsection is text 0 anyway.
3026 .ascii "This lives in the first text subsection. *"
3028 .ascii "But this lives in the second text subsection."
3030 .ascii "This lives in the data section,"
3031 .ascii "in the first data subsection."
3033 .ascii "This lives in the first text section,"
3034 .ascii "immediately following the asterisk (*)."
3037 Each section has a @dfn{location counter} incremented by one for every byte
3038 assembled into that section. Because subsections are merely a convenience
3039 restricted to @command{@value{AS}} there is no concept of a subsection location
3040 counter. There is no way to directly manipulate a location counter---but the
3041 @code{.align} directive changes it, and any label definition captures its
3042 current value. The location counter of the section where statements are being
3043 assembled is said to be the @dfn{active} location counter.
3046 @section bss Section
3049 @cindex common variable storage
3050 The bss section is used for local common variable storage.
3051 You may allocate address space in the bss section, but you may
3052 not dictate data to load into it before your program executes. When
3053 your program starts running, all the contents of the bss
3054 section are zeroed bytes.
3056 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3057 @ref{Lcomm,,@code{.lcomm}}.
3059 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3060 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
3063 When assembling for a target which supports multiple sections, such as ELF or
3064 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3065 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3066 section. Typically the section will only contain symbol definitions and
3067 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3074 Symbols are a central concept: the programmer uses symbols to name
3075 things, the linker uses symbols to link, and the debugger uses symbols
3079 @cindex debuggers, and symbol order
3080 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3081 the same order they were declared. This may break some debuggers.
3086 * Setting Symbols:: Giving Symbols Other Values
3087 * Symbol Names:: Symbol Names
3088 * Dot:: The Special Dot Symbol
3089 * Symbol Attributes:: Symbol Attributes
3096 A @dfn{label} is written as a symbol immediately followed by a colon
3097 @samp{:}. The symbol then represents the current value of the
3098 active location counter, and is, for example, a suitable instruction
3099 operand. You are warned if you use the same symbol to represent two
3100 different locations: the first definition overrides any other
3104 On the HPPA, the usual form for a label need not be immediately followed by a
3105 colon, but instead must start in column zero. Only one label may be defined on
3106 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3107 provides a special directive @code{.label} for defining labels more flexibly.
3110 @node Setting Symbols
3111 @section Giving Symbols Other Values
3113 @cindex assigning values to symbols
3114 @cindex symbol values, assigning
3115 A symbol can be given an arbitrary value by writing a symbol, followed
3116 by an equals sign @samp{=}, followed by an expression
3117 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3118 directive. @xref{Set,,@code{.set}}.
3121 @section Symbol Names
3123 @cindex symbol names
3124 @cindex names, symbol
3125 @ifclear SPECIAL-SYMS
3126 Symbol names begin with a letter or with one of @samp{._}. On most
3127 machines, you can also use @code{$} in symbol names; exceptions are
3128 noted in @ref{Machine Dependencies}. That character may be followed by any
3129 string of digits, letters, dollar signs (unless otherwise noted in
3130 @ref{Machine Dependencies}), and underscores.
3133 For the AMD 29K family, @samp{?} is also allowed in the
3134 body of a symbol name, though not at its beginning.
3139 Symbol names begin with a letter or with one of @samp{._}. On the
3140 Renesas SH or the H8/500, you can also use @code{$} in symbol names. That
3141 character may be followed by any string of digits, letters, dollar signs (save
3142 on the H8/300), and underscores.
3146 Case of letters is significant: @code{foo} is a different symbol name
3149 Each symbol has exactly one name. Each name in an assembly language program
3150 refers to exactly one symbol. You may use that symbol name any number of times
3153 @subheading Local Symbol Names
3155 @cindex local symbol names
3156 @cindex symbol names, local
3157 @cindex temporary symbol names
3158 @cindex symbol names, temporary
3159 Local symbols help compilers and programmers use names temporarily.
3160 They create symbols which are guaranteed to be unique over the entire scope of
3161 the input source code and which can be referred to by a simple notation.
3162 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3163 represents any positive integer). To refer to the most recent previous
3164 definition of that symbol write @samp{@b{N}b}, using the same number as when
3165 you defined the label. To refer to the next definition of a local label, write
3166 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3169 There is no restriction on how you can use these labels, and you can reuse them
3170 too. So that it is possible to repeatedly define the same local label (using
3171 the same number @samp{@b{N}}), although you can only refer to the most recently
3172 defined local label of that number (for a backwards reference) or the next
3173 definition of a specific local label for a forward reference. It is also worth
3174 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3175 implemented in a slightly more efficient manner than the others.
3186 Which is the equivalent of:
3189 label_1: branch label_3
3190 label_2: branch label_1
3191 label_3: branch label_4
3192 label_4: branch label_3
3195 Local symbol names are only a notational device. They are immediately
3196 transformed into more conventional symbol names before the assembler uses them.
3197 The symbol names stored in the symbol table, appearing in error messages and
3198 optionally emitted to the object file. The names are constructed using these
3203 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3204 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3205 used for symbols you are never intended to see. If you use the
3206 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3207 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3208 you may use them in debugging.
3211 This is the number that was used in the local label definition. So if the
3212 label is written @samp{55:} then the number is @samp{55}.
3215 This unusual character is included so you do not accidentally invent a symbol
3216 of the same name. The character has ASCII value of @samp{\002} (control-B).
3218 @item @emph{ordinal number}
3219 This is a serial number to keep the labels distinct. The first definition of
3220 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3221 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3222 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3225 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3226 @code{3:} is named @code{L3@kbd{C-B}44}.
3228 @subheading Dollar Local Labels
3229 @cindex dollar local symbols
3231 @code{@value{AS}} also supports an even more local form of local labels called
3232 dollar labels. These labels go out of scope (ie they become undefined) as soon
3233 as a non-local label is defined. Thus they remain valid for only a small
3234 region of the input source code. Normal local labels, by contrast, remain in
3235 scope for the entire file, or until they are redefined by another occurrence of
3236 the same local label.
3238 Dollar labels are defined in exactly the same way as ordinary local labels,
3239 except that instead of being terminated by a colon, they are terminated by a
3240 dollar sign. eg @samp{@b{55$}}.
3242 They can also be distinguished from ordinary local labels by their transformed
3243 name which uses ASCII character @samp{\001} (control-A) as the magic character
3244 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3245 is named @samp{L6@kbd{C-A}5}.
3248 @section The Special Dot Symbol
3250 @cindex dot (symbol)
3251 @cindex @code{.} (symbol)
3252 @cindex current address
3253 @cindex location counter
3254 The special symbol @samp{.} refers to the current address that
3255 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3256 .long .} defines @code{melvin} to contain its own address.
3257 Assigning a value to @code{.} is treated the same as a @code{.org}
3258 directive. Thus, the expression @samp{.=.+4} is the same as saying
3259 @ifclear no-space-dir
3268 @node Symbol Attributes
3269 @section Symbol Attributes
3271 @cindex symbol attributes
3272 @cindex attributes, symbol
3273 Every symbol has, as well as its name, the attributes ``Value'' and
3274 ``Type''. Depending on output format, symbols can also have auxiliary
3277 The detailed definitions are in @file{a.out.h}.
3280 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3281 all these attributes, and probably won't warn you. This makes the
3282 symbol an externally defined symbol, which is generally what you
3286 * Symbol Value:: Value
3287 * Symbol Type:: Type
3290 * a.out Symbols:: Symbol Attributes: @code{a.out}
3294 * a.out Symbols:: Symbol Attributes: @code{a.out}
3297 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3302 * COFF Symbols:: Symbol Attributes for COFF
3305 * SOM Symbols:: Symbol Attributes for SOM
3312 @cindex value of a symbol
3313 @cindex symbol value
3314 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3315 location in the text, data, bss or absolute sections the value is the
3316 number of addresses from the start of that section to the label.
3317 Naturally for text, data and bss sections the value of a symbol changes
3318 as @code{@value{LD}} changes section base addresses during linking. Absolute
3319 symbols' values do not change during linking: that is why they are
3322 The value of an undefined symbol is treated in a special way. If it is
3323 0 then the symbol is not defined in this assembler source file, and
3324 @code{@value{LD}} tries to determine its value from other files linked into the
3325 same program. You make this kind of symbol simply by mentioning a symbol
3326 name without defining it. A non-zero value represents a @code{.comm}
3327 common declaration. The value is how much common storage to reserve, in
3328 bytes (addresses). The symbol refers to the first address of the
3334 @cindex type of a symbol
3336 The type attribute of a symbol contains relocation (section)
3337 information, any flag settings indicating that a symbol is external, and
3338 (optionally), other information for linkers and debuggers. The exact
3339 format depends on the object-code output format in use.
3344 @c The following avoids a "widow" subsection title. @group would be
3345 @c better if it were available outside examples.
3348 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3350 @cindex @code{b.out} symbol attributes
3351 @cindex symbol attributes, @code{b.out}
3352 These symbol attributes appear only when @command{@value{AS}} is configured for
3353 one of the Berkeley-descended object output formats---@code{a.out} or
3359 @subsection Symbol Attributes: @code{a.out}
3361 @cindex @code{a.out} symbol attributes
3362 @cindex symbol attributes, @code{a.out}
3368 @subsection Symbol Attributes: @code{a.out}
3370 @cindex @code{a.out} symbol attributes
3371 @cindex symbol attributes, @code{a.out}
3375 * Symbol Desc:: Descriptor
3376 * Symbol Other:: Other
3380 @subsubsection Descriptor
3382 @cindex descriptor, of @code{a.out} symbol
3383 This is an arbitrary 16-bit value. You may establish a symbol's
3384 descriptor value by using a @code{.desc} statement
3385 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3386 @command{@value{AS}}.
3389 @subsubsection Other
3391 @cindex other attribute, of @code{a.out} symbol
3392 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3397 @subsection Symbol Attributes for COFF
3399 @cindex COFF symbol attributes
3400 @cindex symbol attributes, COFF
3402 The COFF format supports a multitude of auxiliary symbol attributes;
3403 like the primary symbol attributes, they are set between @code{.def} and
3404 @code{.endef} directives.
3406 @subsubsection Primary Attributes
3408 @cindex primary attributes, COFF symbols
3409 The symbol name is set with @code{.def}; the value and type,
3410 respectively, with @code{.val} and @code{.type}.
3412 @subsubsection Auxiliary Attributes
3414 @cindex auxiliary attributes, COFF symbols
3415 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3416 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3417 table information for COFF.
3422 @subsection Symbol Attributes for SOM
3424 @cindex SOM symbol attributes
3425 @cindex symbol attributes, SOM
3427 The SOM format for the HPPA supports a multitude of symbol attributes set with
3428 the @code{.EXPORT} and @code{.IMPORT} directives.
3430 The attributes are described in @cite{HP9000 Series 800 Assembly
3431 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3432 @code{EXPORT} assembler directive documentation.
3436 @chapter Expressions
3440 @cindex numeric values
3441 An @dfn{expression} specifies an address or numeric value.
3442 Whitespace may precede and/or follow an expression.
3444 The result of an expression must be an absolute number, or else an offset into
3445 a particular section. If an expression is not absolute, and there is not
3446 enough information when @command{@value{AS}} sees the expression to know its
3447 section, a second pass over the source program might be necessary to interpret
3448 the expression---but the second pass is currently not implemented.
3449 @command{@value{AS}} aborts with an error message in this situation.
3452 * Empty Exprs:: Empty Expressions
3453 * Integer Exprs:: Integer Expressions
3457 @section Empty Expressions
3459 @cindex empty expressions
3460 @cindex expressions, empty
3461 An empty expression has no value: it is just whitespace or null.
3462 Wherever an absolute expression is required, you may omit the
3463 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3464 is compatible with other assemblers.
3467 @section Integer Expressions
3469 @cindex integer expressions
3470 @cindex expressions, integer
3471 An @dfn{integer expression} is one or more @emph{arguments} delimited
3472 by @emph{operators}.
3475 * Arguments:: Arguments
3476 * Operators:: Operators
3477 * Prefix Ops:: Prefix Operators
3478 * Infix Ops:: Infix Operators
3482 @subsection Arguments
3484 @cindex expression arguments
3485 @cindex arguments in expressions
3486 @cindex operands in expressions
3487 @cindex arithmetic operands
3488 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3489 contexts arguments are sometimes called ``arithmetic operands''. In
3490 this manual, to avoid confusing them with the ``instruction operands'' of
3491 the machine language, we use the term ``argument'' to refer to parts of
3492 expressions only, reserving the word ``operand'' to refer only to machine
3493 instruction operands.
3495 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3496 @var{section} is one of text, data, bss, absolute,
3497 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3500 Numbers are usually integers.
3502 A number can be a flonum or bignum. In this case, you are warned
3503 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3504 these 32 bits are an integer. You may write integer-manipulating
3505 instructions that act on exotic constants, compatible with other
3508 @cindex subexpressions
3509 Subexpressions are a left parenthesis @samp{(} followed by an integer
3510 expression, followed by a right parenthesis @samp{)}; or a prefix
3511 operator followed by an argument.
3514 @subsection Operators
3516 @cindex operators, in expressions
3517 @cindex arithmetic functions
3518 @cindex functions, in expressions
3519 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3520 operators are followed by an argument. Infix operators appear
3521 between their arguments. Operators may be preceded and/or followed by
3525 @subsection Prefix Operator
3527 @cindex prefix operators
3528 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3529 one argument, which must be absolute.
3531 @c the tex/end tex stuff surrounding this small table is meant to make
3532 @c it align, on the printed page, with the similar table in the next
3533 @c section (which is inside an enumerate).
3535 \global\advance\leftskip by \itemindent
3540 @dfn{Negation}. Two's complement negation.
3542 @dfn{Complementation}. Bitwise not.
3546 \global\advance\leftskip by -\itemindent
3550 @subsection Infix Operators
3552 @cindex infix operators
3553 @cindex operators, permitted arguments
3554 @dfn{Infix operators} take two arguments, one on either side. Operators
3555 have precedence, but operations with equal precedence are performed left
3556 to right. Apart from @code{+} or @option{-}, both arguments must be
3557 absolute, and the result is absolute.
3560 @cindex operator precedence
3561 @cindex precedence of operators
3568 @dfn{Multiplication}.
3571 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3578 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3582 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3586 Intermediate precedence
3591 @dfn{Bitwise Inclusive Or}.
3597 @dfn{Bitwise Exclusive Or}.
3600 @dfn{Bitwise Or Not}.
3607 @cindex addition, permitted arguments
3608 @cindex plus, permitted arguments
3609 @cindex arguments for addition
3611 @dfn{Addition}. If either argument is absolute, the result has the section of
3612 the other argument. You may not add together arguments from different
3615 @cindex subtraction, permitted arguments
3616 @cindex minus, permitted arguments
3617 @cindex arguments for subtraction
3619 @dfn{Subtraction}. If the right argument is absolute, the
3620 result has the section of the left argument.
3621 If both arguments are in the same section, the result is absolute.
3622 You may not subtract arguments from different sections.
3623 @c FIXME is there still something useful to say about undefined - undefined ?
3625 @cindex comparison expressions
3626 @cindex expressions, comparison
3630 @dfn{Is Not Equal To}
3634 @dfn{Is Greater Than}
3636 @dfn{Is Greater Than Or Equal To}
3638 @dfn{Is Less Than Or Equal To}
3640 The comparison operators can be used as infix operators. A true results has a
3641 value of -1 whereas a false result has a value of 0. Note, these operators
3642 perform signed comparisons.
3645 @item Lowest Precedence
3654 These two logical operations can be used to combine the results of sub
3655 expressions. Note, unlike the comparison operators a true result returns a
3656 value of 1 but a false results does still return 0. Also note that the logical
3657 or operator has a slightly lower precedence than logical and.
3662 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3663 address; you can only have a defined section in one of the two arguments.
3666 @chapter Assembler Directives
3668 @cindex directives, machine independent
3669 @cindex pseudo-ops, machine independent
3670 @cindex machine independent directives
3671 All assembler directives have names that begin with a period (@samp{.}).
3672 The rest of the name is letters, usually in lower case.
3674 This chapter discusses directives that are available regardless of the
3675 target machine configuration for the @sc{gnu} assembler.
3677 Some machine configurations provide additional directives.
3678 @xref{Machine Dependencies}.
3681 @ifset machine-directives
3682 @xref{Machine Dependencies} for additional directives.
3687 * Abort:: @code{.abort}
3689 * ABORT:: @code{.ABORT}
3692 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3693 * Altmacro:: @code{.altmacro}
3694 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3695 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3696 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3697 * Byte:: @code{.byte @var{expressions}}
3698 * Comm:: @code{.comm @var{symbol} , @var{length} }
3700 * CFI directives:: @code{.cfi_startproc}, @code{.cfi_endproc}, etc.
3702 * Data:: @code{.data @var{subsection}}
3704 * Def:: @code{.def @var{name}}
3707 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3713 * Double:: @code{.double @var{flonums}}
3714 * Eject:: @code{.eject}
3715 * Else:: @code{.else}
3716 * Elseif:: @code{.elseif}
3719 * Endef:: @code{.endef}
3722 * Endfunc:: @code{.endfunc}
3723 * Endif:: @code{.endif}
3724 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3725 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3727 * Exitm:: @code{.exitm}
3728 * Extern:: @code{.extern}
3729 * Fail:: @code{.fail}
3730 @ifclear no-file-dir
3731 * File:: @code{.file @var{string}}
3734 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3735 * Float:: @code{.float @var{flonums}}
3736 * Func:: @code{.func}
3737 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3739 * Hidden:: @code{.hidden @var{names}}
3742 * hword:: @code{.hword @var{expressions}}
3743 * Ident:: @code{.ident}
3744 * If:: @code{.if @var{absolute expression}}
3745 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3746 * Include:: @code{.include "@var{file}"}
3747 * Int:: @code{.int @var{expressions}}
3749 * Internal:: @code{.internal @var{names}}
3752 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3753 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3754 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3755 * Lflags:: @code{.lflags}
3756 @ifclear no-line-dir
3757 * Line:: @code{.line @var{line-number}}
3760 * Ln:: @code{.ln @var{line-number}}
3761 * Linkonce:: @code{.linkonce [@var{type}]}
3762 * List:: @code{.list}
3763 * Long:: @code{.long @var{expressions}}
3765 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3768 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3769 * MRI:: @code{.mri @var{val}}
3770 * Noaltmacro:: @code{.noaltmacro}
3771 * Nolist:: @code{.nolist}
3772 * Octa:: @code{.octa @var{bignums}}
3773 * Org:: @code{.org @var{new-lc} , @var{fill}}
3774 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3776 * PopSection:: @code{.popsection}
3777 * Previous:: @code{.previous}
3780 * Print:: @code{.print @var{string}}
3782 * Protected:: @code{.protected @var{names}}
3785 * Psize:: @code{.psize @var{lines}, @var{columns}}
3786 * Purgem:: @code{.purgem @var{name}}
3788 * PushSection:: @code{.pushsection @var{name}}
3791 * Quad:: @code{.quad @var{bignums}}
3792 * Rept:: @code{.rept @var{count}}
3793 * Sbttl:: @code{.sbttl "@var{subheading}"}
3795 * Scl:: @code{.scl @var{class}}
3798 * Section:: @code{.section @var{name}}
3801 * Set:: @code{.set @var{symbol}, @var{expression}}
3802 * Short:: @code{.short @var{expressions}}
3803 * Single:: @code{.single @var{flonums}}
3805 * Size:: @code{.size [@var{name} , @var{expression}]}
3808 * Skip:: @code{.skip @var{size} , @var{fill}}
3809 * Sleb128:: @code{.sleb128 @var{expressions}}
3810 * Space:: @code{.space @var{size} , @var{fill}}
3812 * Stab:: @code{.stabd, .stabn, .stabs}
3815 * String:: @code{.string "@var{str}"}
3816 * Struct:: @code{.struct @var{expression}}
3818 * SubSection:: @code{.subsection}
3819 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3823 * Tag:: @code{.tag @var{structname}}
3826 * Text:: @code{.text @var{subsection}}
3827 * Title:: @code{.title "@var{heading}"}
3829 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3832 * Uleb128:: @code{.uleb128 @var{expressions}}
3834 * Val:: @code{.val @var{addr}}
3838 * Version:: @code{.version "@var{string}"}
3839 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3840 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3843 * Weak:: @code{.weak @var{names}}
3844 * Word:: @code{.word @var{expressions}}
3845 * Deprecated:: Deprecated Directives
3849 @section @code{.abort}
3851 @cindex @code{abort} directive
3852 @cindex stopping the assembly
3853 This directive stops the assembly immediately. It is for
3854 compatibility with other assemblers. The original idea was that the
3855 assembly language source would be piped into the assembler. If the sender
3856 of the source quit, it could use this directive tells @command{@value{AS}} to
3857 quit also. One day @code{.abort} will not be supported.
3861 @section @code{.ABORT}
3863 @cindex @code{ABORT} directive
3864 When producing COFF output, @command{@value{AS}} accepts this directive as a
3865 synonym for @samp{.abort}.
3868 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3874 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3876 @cindex padding the location counter
3877 @cindex @code{align} directive
3878 Pad the location counter (in the current subsection) to a particular storage
3879 boundary. The first expression (which must be absolute) is the alignment
3880 required, as described below.
3882 The second expression (also absolute) gives the fill value to be stored in the
3883 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3884 padding bytes are normally zero. However, on some systems, if the section is
3885 marked as containing code and the fill value is omitted, the space is filled
3886 with no-op instructions.
3888 The third expression is also absolute, and is also optional. If it is present,
3889 it is the maximum number of bytes that should be skipped by this alignment
3890 directive. If doing the alignment would require skipping more bytes than the
3891 specified maximum, then the alignment is not done at all. You can omit the
3892 fill value (the second argument) entirely by simply using two commas after the
3893 required alignment; this can be useful if you want the alignment to be filled
3894 with no-op instructions when appropriate.
3896 The way the required alignment is specified varies from system to system.
3897 For the a29k, arc, hppa, i386 using ELF, i860, iq2000, m68k, m88k, or32,
3898 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
3899 alignment request in bytes. For example @samp{.align 8} advances
3900 the location counter until it is a multiple of 8. If the location counter
3901 is already a multiple of 8, no change is needed. For the tic54x, the
3902 first expression is the alignment request in words.
3904 For other systems, including the i386 using a.out format, and the arm and
3905 strongarm, it is the
3906 number of low-order zero bits the location counter must have after
3907 advancement. For example @samp{.align 3} advances the location
3908 counter until it a multiple of 8. If the location counter is already a
3909 multiple of 8, no change is needed.
3911 This inconsistency is due to the different behaviors of the various
3912 native assemblers for these systems which GAS must emulate.
3913 GAS also provides @code{.balign} and @code{.p2align} directives,
3914 described later, which have a consistent behavior across all
3915 architectures (but are specific to GAS).
3918 @section @code{.ascii "@var{string}"}@dots{}
3920 @cindex @code{ascii} directive
3921 @cindex string literals
3922 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3923 separated by commas. It assembles each string (with no automatic
3924 trailing zero byte) into consecutive addresses.
3927 @section @code{.asciz "@var{string}"}@dots{}
3929 @cindex @code{asciz} directive
3930 @cindex zero-terminated strings
3931 @cindex null-terminated strings
3932 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3933 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3936 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3938 @cindex padding the location counter given number of bytes
3939 @cindex @code{balign} directive
3940 Pad the location counter (in the current subsection) to a particular
3941 storage boundary. The first expression (which must be absolute) is the
3942 alignment request in bytes. For example @samp{.balign 8} advances
3943 the location counter until it is a multiple of 8. If the location counter
3944 is already a multiple of 8, no change is needed.
3946 The second expression (also absolute) gives the fill value to be stored in the
3947 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3948 padding bytes are normally zero. However, on some systems, if the section is
3949 marked as containing code and the fill value is omitted, the space is filled
3950 with no-op instructions.
3952 The third expression is also absolute, and is also optional. If it is present,
3953 it is the maximum number of bytes that should be skipped by this alignment
3954 directive. If doing the alignment would require skipping more bytes than the
3955 specified maximum, then the alignment is not done at all. You can omit the
3956 fill value (the second argument) entirely by simply using two commas after the
3957 required alignment; this can be useful if you want the alignment to be filled
3958 with no-op instructions when appropriate.
3960 @cindex @code{balignw} directive
3961 @cindex @code{balignl} directive
3962 The @code{.balignw} and @code{.balignl} directives are variants of the
3963 @code{.balign} directive. The @code{.balignw} directive treats the fill
3964 pattern as a two byte word value. The @code{.balignl} directives treats the
3965 fill pattern as a four byte longword value. For example, @code{.balignw
3966 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3967 filled in with the value 0x368d (the exact placement of the bytes depends upon
3968 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3972 @section @code{.byte @var{expressions}}
3974 @cindex @code{byte} directive
3975 @cindex integers, one byte
3976 @code{.byte} expects zero or more expressions, separated by commas.
3977 Each expression is assembled into the next byte.
3980 @section @code{.comm @var{symbol} , @var{length} }
3982 @cindex @code{comm} directive
3983 @cindex symbol, common
3984 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3985 common symbol in one object file may be merged with a defined or common symbol
3986 of the same name in another object file. If @code{@value{LD}} does not see a
3987 definition for the symbol--just one or more common symbols--then it will
3988 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3989 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3990 the same name, and they do not all have the same size, it will allocate space
3991 using the largest size.
3994 When using ELF, the @code{.comm} directive takes an optional third argument.
3995 This is the desired alignment of the symbol, specified as a byte boundary (for
3996 example, an alignment of 16 means that the least significant 4 bits of the
3997 address should be zero). The alignment must be an absolute expression, and it
3998 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3999 for the common symbol, it will use the alignment when placing the symbol. If
4000 no alignment is specified, @command{@value{AS}} will set the alignment to the
4001 largest power of two less than or equal to the size of the symbol, up to a
4006 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4007 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4010 @node CFI directives
4011 @section @code{.cfi_startproc}
4012 @cindex @code{cfi_startproc} directive
4013 @code{.cfi_startproc} is used at the beginning of each function that
4014 should have an entry in @code{.eh_frame}. It initializes some internal
4015 data structures and emits architecture dependent initial CFI instructions.
4016 Don't forget to close the function by
4017 @code{.cfi_endproc}.
4019 @section @code{.cfi_endproc}
4020 @cindex @code{cfi_endproc} directive
4021 @code{.cfi_endproc} is used at the end of a function where it closes its
4022 unwind entry previously opened by
4023 @code{.cfi_startproc}. and emits it to @code{.eh_frame}.
4025 @section @code{.cfi_def_cfa @var{register}, @var{offset}}
4026 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4027 address from @var{register} and add @var{offset} to it}.
4029 @section @code{.cfi_def_cfa_register @var{register}}
4030 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4031 now on @var{register} will be used instead of the old one. Offset
4034 @section @code{.cfi_def_cfa_offset @var{offset}}
4035 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4036 remains the same, but @var{offset} is new. Note that it is the
4037 absolute offset that will be added to a defined register to compute
4040 @section @code{.cfi_adjust_cfa_offset @var{offset}}
4041 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4042 value that is added/substracted from the previous offset.
4044 @section @code{.cfi_offset @var{register}, @var{offset}}
4045 Previous value of @var{register} is saved at offset @var{offset} from
4048 @section @code{.cfi_rel_offset @var{register}, @var{offset}}
4049 Previous value of @var{register} is saved at offset @var{offset} from
4050 the current CFA register. This is transformed to @code{.cfi_offset}
4051 using the known displacement of the CFA register from the CFA.
4052 This is often easier to use, because the number will match the
4053 code it's annotating.
4055 @section @code{.cfi_window_save}
4056 SPARC register window has been saved.
4058 @section @code{.cfi_escape} @var{expression}[, @dots{}]
4059 Allows the user to add arbitrary bytes to the unwind info. One
4060 might use this to add OS-specific CFI opcodes, or generic CFI
4061 opcodes that GAS does not yet support.
4064 @section @code{.data @var{subsection}}
4066 @cindex @code{data} directive
4067 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4068 end of the data subsection numbered @var{subsection} (which is an
4069 absolute expression). If @var{subsection} is omitted, it defaults
4074 @section @code{.def @var{name}}
4076 @cindex @code{def} directive
4077 @cindex COFF symbols, debugging
4078 @cindex debugging COFF symbols
4079 Begin defining debugging information for a symbol @var{name}; the
4080 definition extends until the @code{.endef} directive is encountered.
4083 This directive is only observed when @command{@value{AS}} is configured for COFF
4084 format output; when producing @code{b.out}, @samp{.def} is recognized,
4091 @section @code{.desc @var{symbol}, @var{abs-expression}}
4093 @cindex @code{desc} directive
4094 @cindex COFF symbol descriptor
4095 @cindex symbol descriptor, COFF
4096 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4097 to the low 16 bits of an absolute expression.
4100 The @samp{.desc} directive is not available when @command{@value{AS}} is
4101 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4102 object format. For the sake of compatibility, @command{@value{AS}} accepts
4103 it, but produces no output, when configured for COFF.
4109 @section @code{.dim}
4111 @cindex @code{dim} directive
4112 @cindex COFF auxiliary symbol information
4113 @cindex auxiliary symbol information, COFF
4114 This directive is generated by compilers to include auxiliary debugging
4115 information in the symbol table. It is only permitted inside
4116 @code{.def}/@code{.endef} pairs.
4119 @samp{.dim} is only meaningful when generating COFF format output; when
4120 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4126 @section @code{.double @var{flonums}}
4128 @cindex @code{double} directive
4129 @cindex floating point numbers (double)
4130 @code{.double} expects zero or more flonums, separated by commas. It
4131 assembles floating point numbers.
4133 The exact kind of floating point numbers emitted depends on how
4134 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4138 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4139 in @sc{ieee} format.
4144 @section @code{.eject}
4146 @cindex @code{eject} directive
4147 @cindex new page, in listings
4148 @cindex page, in listings
4149 @cindex listing control: new page
4150 Force a page break at this point, when generating assembly listings.
4153 @section @code{.else}
4155 @cindex @code{else} directive
4156 @code{.else} is part of the @command{@value{AS}} support for conditional
4157 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
4158 of code to be assembled if the condition for the preceding @code{.if}
4162 @section @code{.elseif}
4164 @cindex @code{elseif} directive
4165 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4166 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
4167 @code{.if} block that would otherwise fill the entire @code{.else} section.
4170 @section @code{.end}
4172 @cindex @code{end} directive
4173 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4174 process anything in the file past the @code{.end} directive.
4178 @section @code{.endef}
4180 @cindex @code{endef} directive
4181 This directive flags the end of a symbol definition begun with
4185 @samp{.endef} is only meaningful when generating COFF format output; if
4186 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4187 directive but ignores it.
4192 @section @code{.endfunc}
4193 @cindex @code{endfunc} directive
4194 @code{.endfunc} marks the end of a function specified with @code{.func}.
4197 @section @code{.endif}
4199 @cindex @code{endif} directive
4200 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4201 it marks the end of a block of code that is only assembled
4202 conditionally. @xref{If,,@code{.if}}.
4205 @section @code{.equ @var{symbol}, @var{expression}}
4207 @cindex @code{equ} directive
4208 @cindex assigning values to symbols
4209 @cindex symbols, assigning values to
4210 This directive sets the value of @var{symbol} to @var{expression}.
4211 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
4214 The syntax for @code{equ} on the HPPA is
4215 @samp{@var{symbol} .equ @var{expression}}.
4219 @section @code{.equiv @var{symbol}, @var{expression}}
4220 @cindex @code{equiv} directive
4221 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4222 the assembler will signal an error if @var{symbol} is already defined. Note a
4223 symbol which has been referenced but not actually defined is considered to be
4226 Except for the contents of the error message, this is roughly equivalent to
4235 @section @code{.err}
4236 @cindex @code{err} directive
4237 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4238 message and, unless the @option{-Z} option was used, it will not generate an
4239 object file. This can be used to signal error an conditionally compiled code.
4242 @section @code{.exitm}
4243 Exit early from the current macro definition. @xref{Macro}.
4246 @section @code{.extern}
4248 @cindex @code{extern} directive
4249 @code{.extern} is accepted in the source program---for compatibility
4250 with other assemblers---but it is ignored. @command{@value{AS}} treats
4251 all undefined symbols as external.
4254 @section @code{.fail @var{expression}}
4256 @cindex @code{fail} directive
4257 Generates an error or a warning. If the value of the @var{expression} is 500
4258 or more, @command{@value{AS}} will print a warning message. If the value is less
4259 than 500, @command{@value{AS}} will print an error message. The message will
4260 include the value of @var{expression}. This can occasionally be useful inside
4261 complex nested macros or conditional assembly.
4263 @ifclear no-file-dir
4265 @section @code{.file @var{string}}
4267 @cindex @code{file} directive
4268 @cindex logical file name
4269 @cindex file name, logical
4270 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4271 file. @var{string} is the new file name. In general, the filename is
4272 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4273 to specify an empty file name, you must give the quotes--@code{""}. This
4274 statement may go away in future: it is only recognized to be compatible with
4275 old @command{@value{AS}} programs.
4277 In some configurations of @command{@value{AS}}, @code{.file} has already been
4278 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4283 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4285 @cindex @code{fill} directive
4286 @cindex writing patterns in memory
4287 @cindex patterns, writing in memory
4288 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4289 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4290 may be zero or more. @var{Size} may be zero or more, but if it is
4291 more than 8, then it is deemed to have the value 8, compatible with
4292 other people's assemblers. The contents of each @var{repeat} bytes
4293 is taken from an 8-byte number. The highest order 4 bytes are
4294 zero. The lowest order 4 bytes are @var{value} rendered in the
4295 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4296 Each @var{size} bytes in a repetition is taken from the lowest order
4297 @var{size} bytes of this number. Again, this bizarre behavior is
4298 compatible with other people's assemblers.
4300 @var{size} and @var{value} are optional.
4301 If the second comma and @var{value} are absent, @var{value} is
4302 assumed zero. If the first comma and following tokens are absent,
4303 @var{size} is assumed to be 1.
4306 @section @code{.float @var{flonums}}
4308 @cindex floating point numbers (single)
4309 @cindex @code{float} directive
4310 This directive assembles zero or more flonums, separated by commas. It
4311 has the same effect as @code{.single}.
4313 The exact kind of floating point numbers emitted depends on how
4314 @command{@value{AS}} is configured.
4315 @xref{Machine Dependencies}.
4319 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4320 in @sc{ieee} format.
4325 @section @code{.func @var{name}[,@var{label}]}
4326 @cindex @code{func} directive
4327 @code{.func} emits debugging information to denote function @var{name}, and
4328 is ignored unless the file is assembled with debugging enabled.
4329 Only @samp{--gstabs[+]} is currently supported.
4330 @var{label} is the entry point of the function and if omitted @var{name}
4331 prepended with the @samp{leading char} is used.
4332 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4333 All functions are currently defined to have @code{void} return type.
4334 The function must be terminated with @code{.endfunc}.
4337 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4339 @cindex @code{global} directive
4340 @cindex symbol, making visible to linker
4341 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4342 @var{symbol} in your partial program, its value is made available to
4343 other partial programs that are linked with it. Otherwise,
4344 @var{symbol} takes its attributes from a symbol of the same name
4345 from another file linked into the same program.
4347 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4348 compatibility with other assemblers.
4351 On the HPPA, @code{.global} is not always enough to make it accessible to other
4352 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4353 @xref{HPPA Directives,, HPPA Assembler Directives}.
4358 @section @code{.hidden @var{names}}
4360 @cindex @code{hidden} directive
4362 This is one of the ELF visibility directives. The other two are
4363 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4364 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4366 This directive overrides the named symbols default visibility (which is set by
4367 their binding: local, global or weak). The directive sets the visibility to
4368 @code{hidden} which means that the symbols are not visible to other components.
4369 Such symbols are always considered to be @code{protected} as well.
4373 @section @code{.hword @var{expressions}}
4375 @cindex @code{hword} directive
4376 @cindex integers, 16-bit
4377 @cindex numbers, 16-bit
4378 @cindex sixteen bit integers
4379 This expects zero or more @var{expressions}, and emits
4380 a 16 bit number for each.
4383 This directive is a synonym for @samp{.short}; depending on the target
4384 architecture, it may also be a synonym for @samp{.word}.
4388 This directive is a synonym for @samp{.short}.
4391 This directive is a synonym for both @samp{.short} and @samp{.word}.
4396 @section @code{.ident}
4398 @cindex @code{ident} directive
4399 This directive is used by some assemblers to place tags in object files.
4400 @command{@value{AS}} simply accepts the directive for source-file
4401 compatibility with such assemblers, but does not actually emit anything
4405 @section @code{.if @var{absolute expression}}
4407 @cindex conditional assembly
4408 @cindex @code{if} directive
4409 @code{.if} marks the beginning of a section of code which is only
4410 considered part of the source program being assembled if the argument
4411 (which must be an @var{absolute expression}) is non-zero. The end of
4412 the conditional section of code must be marked by @code{.endif}
4413 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4414 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4415 If you have several conditions to check, @code{.elseif} may be used to avoid
4416 nesting blocks if/else within each subsequent @code{.else} block.
4418 The following variants of @code{.if} are also supported:
4420 @cindex @code{ifdef} directive
4421 @item .ifdef @var{symbol}
4422 Assembles the following section of code if the specified @var{symbol}
4423 has been defined. Note a symbol which has been referenced but not yet defined
4424 is considered to be undefined.
4426 @cindex @code{ifc} directive
4427 @item .ifc @var{string1},@var{string2}
4428 Assembles the following section of code if the two strings are the same. The
4429 strings may be optionally quoted with single quotes. If they are not quoted,
4430 the first string stops at the first comma, and the second string stops at the
4431 end of the line. Strings which contain whitespace should be quoted. The
4432 string comparison is case sensitive.
4434 @cindex @code{ifeq} directive
4435 @item .ifeq @var{absolute expression}
4436 Assembles the following section of code if the argument is zero.
4438 @cindex @code{ifeqs} directive
4439 @item .ifeqs @var{string1},@var{string2}
4440 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4442 @cindex @code{ifge} directive
4443 @item .ifge @var{absolute expression}
4444 Assembles the following section of code if the argument is greater than or
4447 @cindex @code{ifgt} directive
4448 @item .ifgt @var{absolute expression}
4449 Assembles the following section of code if the argument is greater than zero.
4451 @cindex @code{ifle} directive
4452 @item .ifle @var{absolute expression}
4453 Assembles the following section of code if the argument is less than or equal
4456 @cindex @code{iflt} directive
4457 @item .iflt @var{absolute expression}
4458 Assembles the following section of code if the argument is less than zero.
4460 @cindex @code{ifnc} directive
4461 @item .ifnc @var{string1},@var{string2}.
4462 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4463 following section of code if the two strings are not the same.
4465 @cindex @code{ifndef} directive
4466 @cindex @code{ifnotdef} directive
4467 @item .ifndef @var{symbol}
4468 @itemx .ifnotdef @var{symbol}
4469 Assembles the following section of code if the specified @var{symbol}
4470 has not been defined. Both spelling variants are equivalent. Note a symbol
4471 which has been referenced but not yet defined is considered to be undefined.
4473 @cindex @code{ifne} directive
4474 @item .ifne @var{absolute expression}
4475 Assembles the following section of code if the argument is not equal to zero
4476 (in other words, this is equivalent to @code{.if}).
4478 @cindex @code{ifnes} directive
4479 @item .ifnes @var{string1},@var{string2}
4480 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4481 following section of code if the two strings are not the same.
4485 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4487 @cindex @code{incbin} directive
4488 @cindex binary files, including
4489 The @code{incbin} directive includes @var{file} verbatim at the current
4490 location. You can control the search paths used with the @samp{-I} command-line
4491 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4494 The @var{skip} argument skips a number of bytes from the start of the
4495 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4496 read. Note that the data is not aligned in any way, so it is the user's
4497 responsibility to make sure that proper alignment is provided both before and
4498 after the @code{incbin} directive.
4501 @section @code{.include "@var{file}"}
4503 @cindex @code{include} directive
4504 @cindex supporting files, including
4505 @cindex files, including
4506 This directive provides a way to include supporting files at specified
4507 points in your source program. The code from @var{file} is assembled as
4508 if it followed the point of the @code{.include}; when the end of the
4509 included file is reached, assembly of the original file continues. You
4510 can control the search paths used with the @samp{-I} command-line option
4511 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4515 @section @code{.int @var{expressions}}
4517 @cindex @code{int} directive
4518 @cindex integers, 32-bit
4519 Expect zero or more @var{expressions}, of any section, separated by commas.
4520 For each expression, emit a number that, at run time, is the value of that
4521 expression. The byte order and bit size of the number depends on what kind
4522 of target the assembly is for.
4526 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4527 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
4534 @section @code{.internal @var{names}}
4536 @cindex @code{internal} directive
4538 This is one of the ELF visibility directives. The other two are
4539 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4540 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4542 This directive overrides the named symbols default visibility (which is set by
4543 their binding: local, global or weak). The directive sets the visibility to
4544 @code{internal} which means that the symbols are considered to be @code{hidden}
4545 (i.e., not visible to other components), and that some extra, processor specific
4546 processing must also be performed upon the symbols as well.
4550 @section @code{.irp @var{symbol},@var{values}}@dots{}
4552 @cindex @code{irp} directive
4553 Evaluate a sequence of statements assigning different values to @var{symbol}.
4554 The sequence of statements starts at the @code{.irp} directive, and is
4555 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4556 set to @var{value}, and the sequence of statements is assembled. If no
4557 @var{value} is listed, the sequence of statements is assembled once, with
4558 @var{symbol} set to the null string. To refer to @var{symbol} within the
4559 sequence of statements, use @var{\symbol}.
4561 For example, assembling
4569 is equivalent to assembling
4578 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4580 @cindex @code{irpc} directive
4581 Evaluate a sequence of statements assigning different values to @var{symbol}.
4582 The sequence of statements starts at the @code{.irpc} directive, and is
4583 terminated by an @code{.endr} directive. For each character in @var{value},
4584 @var{symbol} is set to the character, and the sequence of statements is
4585 assembled. If no @var{value} is listed, the sequence of statements is
4586 assembled once, with @var{symbol} set to the null string. To refer to
4587 @var{symbol} within the sequence of statements, use @var{\symbol}.
4589 For example, assembling
4597 is equivalent to assembling
4606 @section @code{.lcomm @var{symbol} , @var{length}}
4608 @cindex @code{lcomm} directive
4609 @cindex local common symbols
4610 @cindex symbols, local common
4611 Reserve @var{length} (an absolute expression) bytes for a local common
4612 denoted by @var{symbol}. The section and value of @var{symbol} are
4613 those of the new local common. The addresses are allocated in the bss
4614 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4615 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4616 not visible to @code{@value{LD}}.
4619 Some targets permit a third argument to be used with @code{.lcomm}. This
4620 argument specifies the desired alignment of the symbol in the bss section.
4624 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4625 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4629 @section @code{.lflags}
4631 @cindex @code{lflags} directive (ignored)
4632 @command{@value{AS}} accepts this directive, for compatibility with other
4633 assemblers, but ignores it.
4635 @ifclear no-line-dir
4637 @section @code{.line @var{line-number}}
4639 @cindex @code{line} directive
4643 @section @code{.ln @var{line-number}}
4645 @cindex @code{ln} directive
4647 @cindex logical line number
4649 Change the logical line number. @var{line-number} must be an absolute
4650 expression. The next line has that logical line number. Therefore any other
4651 statements on the current line (after a statement separator character) are
4652 reported as on logical line number @var{line-number} @minus{} 1. One day
4653 @command{@value{AS}} will no longer support this directive: it is recognized only
4654 for compatibility with existing assembler programs.
4658 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4659 not available; use the synonym @code{.ln} in that context.
4664 @ifclear no-line-dir
4665 Even though this is a directive associated with the @code{a.out} or
4666 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4667 when producing COFF output, and treats @samp{.line} as though it
4668 were the COFF @samp{.ln} @emph{if} it is found outside a
4669 @code{.def}/@code{.endef} pair.
4671 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4672 used by compilers to generate auxiliary symbol information for
4677 @section @code{.linkonce [@var{type}]}
4679 @cindex @code{linkonce} directive
4680 @cindex common sections
4681 Mark the current section so that the linker only includes a single copy of it.
4682 This may be used to include the same section in several different object files,
4683 but ensure that the linker will only include it once in the final output file.
4684 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4685 Duplicate sections are detected based on the section name, so it should be
4688 This directive is only supported by a few object file formats; as of this
4689 writing, the only object file format which supports it is the Portable
4690 Executable format used on Windows NT.
4692 The @var{type} argument is optional. If specified, it must be one of the
4693 following strings. For example:
4697 Not all types may be supported on all object file formats.
4701 Silently discard duplicate sections. This is the default.
4704 Warn if there are duplicate sections, but still keep only one copy.
4707 Warn if any of the duplicates have different sizes.
4710 Warn if any of the duplicates do not have exactly the same contents.
4714 @section @code{.ln @var{line-number}}
4716 @cindex @code{ln} directive
4717 @ifclear no-line-dir
4718 @samp{.ln} is a synonym for @samp{.line}.
4721 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4722 must be an absolute expression. The next line has that logical
4723 line number, so any other statements on the current line (after a
4724 statement separator character @code{;}) are reported as on logical
4725 line number @var{line-number} @minus{} 1.
4728 This directive is accepted, but ignored, when @command{@value{AS}} is
4729 configured for @code{b.out}; its effect is only associated with COFF
4735 @section @code{.mri @var{val}}
4737 @cindex @code{mri} directive
4738 @cindex MRI mode, temporarily
4739 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4740 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4741 affects code assembled until the next @code{.mri} directive, or until the end
4742 of the file. @xref{M, MRI mode, MRI mode}.
4745 @section @code{.list}
4747 @cindex @code{list} directive
4748 @cindex listing control, turning on
4749 Control (in conjunction with the @code{.nolist} directive) whether or
4750 not assembly listings are generated. These two directives maintain an
4751 internal counter (which is zero initially). @code{.list} increments the
4752 counter, and @code{.nolist} decrements it. Assembly listings are
4753 generated whenever the counter is greater than zero.
4755 By default, listings are disabled. When you enable them (with the
4756 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4757 the initial value of the listing counter is one.
4760 @section @code{.long @var{expressions}}
4762 @cindex @code{long} directive
4763 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4766 @c no one seems to know what this is for or whether this description is
4767 @c what it really ought to do
4769 @section @code{.lsym @var{symbol}, @var{expression}}
4771 @cindex @code{lsym} directive
4772 @cindex symbol, not referenced in assembly
4773 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4774 the hash table, ensuring it cannot be referenced by name during the
4775 rest of the assembly. This sets the attributes of the symbol to be
4776 the same as the expression value:
4778 @var{other} = @var{descriptor} = 0
4779 @var{type} = @r{(section of @var{expression})}
4780 @var{value} = @var{expression}
4783 The new symbol is not flagged as external.
4787 @section @code{.macro}
4790 The commands @code{.macro} and @code{.endm} allow you to define macros that
4791 generate assembly output. For example, this definition specifies a macro
4792 @code{sum} that puts a sequence of numbers into memory:
4795 .macro sum from=0, to=5
4804 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4816 @item .macro @var{macname}
4817 @itemx .macro @var{macname} @var{macargs} @dots{}
4818 @cindex @code{macro} directive
4819 Begin the definition of a macro called @var{macname}. If your macro
4820 definition requires arguments, specify their names after the macro name,
4821 separated by commas or spaces. You can supply a default value for any
4822 macro argument by following the name with @samp{=@var{deflt}}. For
4823 example, these are all valid @code{.macro} statements:
4827 Begin the definition of a macro called @code{comm}, which takes no
4830 @item .macro plus1 p, p1
4831 @itemx .macro plus1 p p1
4832 Either statement begins the definition of a macro called @code{plus1},
4833 which takes two arguments; within the macro definition, write
4834 @samp{\p} or @samp{\p1} to evaluate the arguments.
4836 @item .macro reserve_str p1=0 p2
4837 Begin the definition of a macro called @code{reserve_str}, with two
4838 arguments. The first argument has a default value, but not the second.
4839 After the definition is complete, you can call the macro either as
4840 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4841 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4842 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4843 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4846 When you call a macro, you can specify the argument values either by
4847 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4848 @samp{sum to=17, from=9}.
4851 @cindex @code{endm} directive
4852 Mark the end of a macro definition.
4855 @cindex @code{exitm} directive
4856 Exit early from the current macro definition.
4858 @cindex number of macros executed
4859 @cindex macros, count executed
4861 @command{@value{AS}} maintains a counter of how many macros it has
4862 executed in this pseudo-variable; you can copy that number to your
4863 output with @samp{\@@}, but @emph{only within a macro definition}.
4865 @item LOCAL @var{name} [ , @dots{} ]
4866 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4867 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
4868 @xref{Altmacro,,@code{.altmacro}}.
4872 @section @code{.altmacro}
4873 Enable alternate macro mode, enabling:
4876 @item LOCAL @var{name} [ , @dots{} ]
4877 One additional directive, @code{LOCAL}, is available. It is used to
4878 generate a string replacement for each of the @var{name} arguments, and
4879 replace any instances of @var{name} in each macro expansion. The
4880 replacement string is unique in the assembly, and different for each
4881 separate macro expansion. @code{LOCAL} allows you to write macros that
4882 define symbols, without fear of conflict between separate macro expansions.
4884 @item String delimiters
4885 You can write strings delimited in these other ways besides
4886 @code{"@var{string}"}:
4889 @item '@var{string}'
4890 You can delimit strings with single-quote charaters.
4892 @item <@var{string}>
4893 You can delimit strings with matching angle brackets.
4896 @item single-character string escape
4897 To include any single character literally in a string (even if the
4898 character would otherwise have some special meaning), you can prefix the
4899 character with @samp{!} (an exclamation mark). For example, you can
4900 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4902 @item Expression results as strings
4903 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4904 and use the result as a string.
4908 @section @code{.noaltmacro}
4909 Disable alternate macro mode. @ref{Altmacro}
4912 @section @code{.nolist}
4914 @cindex @code{nolist} directive
4915 @cindex listing control, turning off
4916 Control (in conjunction with the @code{.list} directive) whether or
4917 not assembly listings are generated. These two directives maintain an
4918 internal counter (which is zero initially). @code{.list} increments the
4919 counter, and @code{.nolist} decrements it. Assembly listings are
4920 generated whenever the counter is greater than zero.
4923 @section @code{.octa @var{bignums}}
4925 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4926 @cindex @code{octa} directive
4927 @cindex integer, 16-byte
4928 @cindex sixteen byte integer
4929 This directive expects zero or more bignums, separated by commas. For each
4930 bignum, it emits a 16-byte integer.
4932 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4933 hence @emph{octa}-word for 16 bytes.
4936 @section @code{.org @var{new-lc} , @var{fill}}
4938 @cindex @code{org} directive
4939 @cindex location counter, advancing
4940 @cindex advancing location counter
4941 @cindex current address, advancing
4942 Advance the location counter of the current section to
4943 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4944 expression with the same section as the current subsection. That is,
4945 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4946 wrong section, the @code{.org} directive is ignored. To be compatible
4947 with former assemblers, if the section of @var{new-lc} is absolute,
4948 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4949 is the same as the current subsection.
4951 @code{.org} may only increase the location counter, or leave it
4952 unchanged; you cannot use @code{.org} to move the location counter
4955 @c double negative used below "not undefined" because this is a specific
4956 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4957 @c section. doc@cygnus.com 18feb91
4958 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4959 may not be undefined. If you really detest this restriction we eagerly await
4960 a chance to share your improved assembler.
4962 Beware that the origin is relative to the start of the section, not
4963 to the start of the subsection. This is compatible with other
4964 people's assemblers.
4966 When the location counter (of the current subsection) is advanced, the
4967 intervening bytes are filled with @var{fill} which should be an
4968 absolute expression. If the comma and @var{fill} are omitted,
4969 @var{fill} defaults to zero.
4972 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4974 @cindex padding the location counter given a power of two
4975 @cindex @code{p2align} directive
4976 Pad the location counter (in the current subsection) to a particular
4977 storage boundary. The first expression (which must be absolute) is the
4978 number of low-order zero bits the location counter must have after
4979 advancement. For example @samp{.p2align 3} advances the location
4980 counter until it a multiple of 8. If the location counter is already a
4981 multiple of 8, no change is needed.
4983 The second expression (also absolute) gives the fill value to be stored in the
4984 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4985 padding bytes are normally zero. However, on some systems, if the section is
4986 marked as containing code and the fill value is omitted, the space is filled
4987 with no-op instructions.
4989 The third expression is also absolute, and is also optional. If it is present,
4990 it is the maximum number of bytes that should be skipped by this alignment
4991 directive. If doing the alignment would require skipping more bytes than the
4992 specified maximum, then the alignment is not done at all. You can omit the
4993 fill value (the second argument) entirely by simply using two commas after the
4994 required alignment; this can be useful if you want the alignment to be filled
4995 with no-op instructions when appropriate.
4997 @cindex @code{p2alignw} directive
4998 @cindex @code{p2alignl} directive
4999 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5000 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5001 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5002 fill pattern as a four byte longword value. For example, @code{.p2alignw
5003 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5004 filled in with the value 0x368d (the exact placement of the bytes depends upon
5005 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5010 @section @code{.previous}
5012 @cindex @code{previous} directive
5013 @cindex Section Stack
5014 This is one of the ELF section stack manipulation directives. The others are
5015 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5016 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5017 (@pxref{PopSection}).
5019 This directive swaps the current section (and subsection) with most recently
5020 referenced section (and subsection) prior to this one. Multiple
5021 @code{.previous} directives in a row will flip between two sections (and their
5024 In terms of the section stack, this directive swaps the current section with
5025 the top section on the section stack.
5030 @section @code{.popsection}
5032 @cindex @code{popsection} directive
5033 @cindex Section Stack
5034 This is one of the ELF section stack manipulation directives. The others are
5035 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5036 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5039 This directive replaces the current section (and subsection) with the top
5040 section (and subsection) on the section stack. This section is popped off the
5045 @section @code{.print @var{string}}
5047 @cindex @code{print} directive
5048 @command{@value{AS}} will print @var{string} on the standard output during
5049 assembly. You must put @var{string} in double quotes.
5053 @section @code{.protected @var{names}}
5055 @cindex @code{protected} directive
5057 This is one of the ELF visibility directives. The other two are
5058 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
5060 This directive overrides the named symbols default visibility (which is set by
5061 their binding: local, global or weak). The directive sets the visibility to
5062 @code{protected} which means that any references to the symbols from within the
5063 components that defines them must be resolved to the definition in that
5064 component, even if a definition in another component would normally preempt
5069 @section @code{.psize @var{lines} , @var{columns}}
5071 @cindex @code{psize} directive
5072 @cindex listing control: paper size
5073 @cindex paper size, for listings
5074 Use this directive to declare the number of lines---and, optionally, the
5075 number of columns---to use for each page, when generating listings.
5077 If you do not use @code{.psize}, listings use a default line-count
5078 of 60. You may omit the comma and @var{columns} specification; the
5079 default width is 200 columns.
5081 @command{@value{AS}} generates formfeeds whenever the specified number of
5082 lines is exceeded (or whenever you explicitly request one, using
5085 If you specify @var{lines} as @code{0}, no formfeeds are generated save
5086 those explicitly specified with @code{.eject}.
5089 @section @code{.purgem @var{name}}
5091 @cindex @code{purgem} directive
5092 Undefine the macro @var{name}, so that later uses of the string will not be
5093 expanded. @xref{Macro}.
5097 @section @code{.pushsection @var{name} , @var{subsection}}
5099 @cindex @code{pushsection} directive
5100 @cindex Section Stack
5101 This is one of the ELF section stack manipulation directives. The others are
5102 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5103 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5106 This directive pushes the current section (and subsection) onto the
5107 top of the section stack, and then replaces the current section and
5108 subsection with @code{name} and @code{subsection}.
5112 @section @code{.quad @var{bignums}}
5114 @cindex @code{quad} directive
5115 @code{.quad} expects zero or more bignums, separated by commas. For
5116 each bignum, it emits
5118 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
5119 warning message; and just takes the lowest order 8 bytes of the bignum.
5120 @cindex eight-byte integer
5121 @cindex integer, 8-byte
5123 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
5124 hence @emph{quad}-word for 8 bytes.
5127 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
5128 warning message; and just takes the lowest order 16 bytes of the bignum.
5129 @cindex sixteen-byte integer
5130 @cindex integer, 16-byte
5134 @section @code{.rept @var{count}}
5136 @cindex @code{rept} directive
5137 Repeat the sequence of lines between the @code{.rept} directive and the next
5138 @code{.endr} directive @var{count} times.
5140 For example, assembling
5148 is equivalent to assembling
5157 @section @code{.sbttl "@var{subheading}"}
5159 @cindex @code{sbttl} directive
5160 @cindex subtitles for listings
5161 @cindex listing control: subtitle
5162 Use @var{subheading} as the title (third line, immediately after the
5163 title line) when generating assembly listings.
5165 This directive affects subsequent pages, as well as the current page if
5166 it appears within ten lines of the top of a page.
5170 @section @code{.scl @var{class}}
5172 @cindex @code{scl} directive
5173 @cindex symbol storage class (COFF)
5174 @cindex COFF symbol storage class
5175 Set the storage-class value for a symbol. This directive may only be
5176 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
5177 whether a symbol is static or external, or it may record further
5178 symbolic debugging information.
5181 The @samp{.scl} directive is primarily associated with COFF output; when
5182 configured to generate @code{b.out} output format, @command{@value{AS}}
5183 accepts this directive but ignores it.
5189 @section @code{.section @var{name}}
5191 @cindex named section
5192 Use the @code{.section} directive to assemble the following code into a section
5195 This directive is only supported for targets that actually support arbitrarily
5196 named sections; on @code{a.out} targets, for example, it is not accepted, even
5197 with a standard @code{a.out} section name.
5201 @c only print the extra heading if both COFF and ELF are set
5202 @subheading COFF Version
5205 @cindex @code{section} directive (COFF version)
5206 For COFF targets, the @code{.section} directive is used in one of the following
5210 .section @var{name}[, "@var{flags}"]
5211 .section @var{name}[, @var{subsegment}]
5214 If the optional argument is quoted, it is taken as flags to use for the
5215 section. Each flag is a single character. The following flags are recognized:
5218 bss section (uninitialized data)
5220 section is not loaded
5230 shared section (meaningful for PE targets)
5232 ignored. (For compatibility with the ELF version)
5235 If no flags are specified, the default flags depend upon the section name. If
5236 the section name is not recognized, the default will be for the section to be
5237 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
5238 from the section, rather than adding them, so if they are used on their own it
5239 will be as if no flags had been specified at all.
5241 If the optional argument to the @code{.section} directive is not quoted, it is
5242 taken as a subsegment number (@pxref{Sub-Sections}).
5247 @c only print the extra heading if both COFF and ELF are set
5248 @subheading ELF Version
5251 @cindex Section Stack
5252 This is one of the ELF section stack manipulation directives. The others are
5253 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5254 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5255 @code{.previous} (@pxref{Previous}).
5257 @cindex @code{section} directive (ELF version)
5258 For ELF targets, the @code{.section} directive is used like this:
5261 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]
5264 The optional @var{flags} argument is a quoted string which may contain any
5265 combination of the following characters:
5268 section is allocatable
5272 section is executable
5274 section is mergeable
5276 section contains zero terminated strings
5278 section is a member of a section group
5280 section is used for thread-local-storage
5283 The optional @var{type} argument may contain one of the following constants:
5286 section contains data
5288 section does not contain data (i.e., section only occupies space)
5290 section contains data which is used by things other than the program
5292 section contains an array of pointers to init functions
5294 section contains an array of pointers to finish functions
5295 @item @@preinit_array
5296 section contains an array of pointers to pre-init functions
5299 Many targets only support the first three section types.
5301 Note on targets where the @code{@@} character is the start of a comment (eg
5302 ARM) then another character is used instead. For example the ARM port uses the
5305 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
5306 be specified as well as an extra argument - @var{entsize} - like this:
5309 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
5312 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
5313 constants, each @var{entsize} octets long. Sections with both @code{M} and
5314 @code{S} must contain zero terminated strings where each character is
5315 @var{entsize} bytes long. The linker may remove duplicates within sections with
5316 the same name, same entity size and same flags. @var{entsize} must be an
5317 absolute expression.
5319 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
5320 be present along with an additional field like this:
5323 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
5326 The @var{GroupName} field specifies the name of the section group to which this
5327 particular section belongs. The optional linkage field can contain:
5330 indicates that only one copy of this section should be retained
5335 Note - if both the @var{M} and @var{G} flags are present then the fields for
5336 the Merge flag should come first, like this:
5339 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
5342 If no flags are specified, the default flags depend upon the section name. If
5343 the section name is not recognized, the default will be for the section to have
5344 none of the above flags: it will not be allocated in memory, nor writable, nor
5345 executable. The section will contain data.
5347 For ELF targets, the assembler supports another type of @code{.section}
5348 directive for compatibility with the Solaris assembler:
5351 .section "@var{name}"[, @var{flags}...]
5354 Note that the section name is quoted. There may be a sequence of comma
5358 section is allocatable
5362 section is executable
5364 section is used for thread local storage
5367 This directive replaces the current section and subsection. See the
5368 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
5369 some examples of how this directive and the other section stack directives
5375 @section @code{.set @var{symbol}, @var{expression}}
5377 @cindex @code{set} directive
5378 @cindex symbol value, setting
5379 Set the value of @var{symbol} to @var{expression}. This
5380 changes @var{symbol}'s value and type to conform to
5381 @var{expression}. If @var{symbol} was flagged as external, it remains
5382 flagged (@pxref{Symbol Attributes}).
5384 You may @code{.set} a symbol many times in the same assembly.
5386 If you @code{.set} a global symbol, the value stored in the object
5387 file is the last value stored into it.
5390 The syntax for @code{set} on the HPPA is
5391 @samp{@var{symbol} .set @var{expression}}.
5395 @section @code{.short @var{expressions}}
5397 @cindex @code{short} directive
5399 @code{.short} is normally the same as @samp{.word}.
5400 @xref{Word,,@code{.word}}.
5402 In some configurations, however, @code{.short} and @code{.word} generate
5403 numbers of different lengths; @pxref{Machine Dependencies}.
5407 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5410 This expects zero or more @var{expressions}, and emits
5411 a 16 bit number for each.
5416 @section @code{.single @var{flonums}}
5418 @cindex @code{single} directive
5419 @cindex floating point numbers (single)
5420 This directive assembles zero or more flonums, separated by commas. It
5421 has the same effect as @code{.float}.
5423 The exact kind of floating point numbers emitted depends on how
5424 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5428 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5429 numbers in @sc{ieee} format.
5435 @section @code{.size}
5437 This directive is used to set the size associated with a symbol.
5441 @c only print the extra heading if both COFF and ELF are set
5442 @subheading COFF Version
5445 @cindex @code{size} directive (COFF version)
5446 For COFF targets, the @code{.size} directive is only permitted inside
5447 @code{.def}/@code{.endef} pairs. It is used like this:
5450 .size @var{expression}
5454 @samp{.size} is only meaningful when generating COFF format output; when
5455 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5462 @c only print the extra heading if both COFF and ELF are set
5463 @subheading ELF Version
5466 @cindex @code{size} directive (ELF version)
5467 For ELF targets, the @code{.size} directive is used like this:
5470 .size @var{name} , @var{expression}
5473 This directive sets the size associated with a symbol @var{name}.
5474 The size in bytes is computed from @var{expression} which can make use of label
5475 arithmetic. This directive is typically used to set the size of function
5481 @section @code{.sleb128 @var{expressions}}
5483 @cindex @code{sleb128} directive
5484 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5485 compact, variable length representation of numbers used by the DWARF
5486 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5488 @ifclear no-space-dir
5490 @section @code{.skip @var{size} , @var{fill}}
5492 @cindex @code{skip} directive
5493 @cindex filling memory
5494 This directive emits @var{size} bytes, each of value @var{fill}. Both
5495 @var{size} and @var{fill} are absolute expressions. If the comma and
5496 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5500 @section @code{.space @var{size} , @var{fill}}
5502 @cindex @code{space} directive
5503 @cindex filling memory
5504 This directive emits @var{size} bytes, each of value @var{fill}. Both
5505 @var{size} and @var{fill} are absolute expressions. If the comma
5506 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5511 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5512 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5513 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5514 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5523 @section @code{.space}
5524 @cindex @code{space} directive
5526 On the AMD 29K, this directive is ignored; it is accepted for
5527 compatibility with other AMD 29K assemblers.
5530 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5531 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5537 @section @code{.stabd, .stabn, .stabs}
5539 @cindex symbolic debuggers, information for
5540 @cindex @code{stab@var{x}} directives
5541 There are three directives that begin @samp{.stab}.
5542 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5543 The symbols are not entered in the @command{@value{AS}} hash table: they
5544 cannot be referenced elsewhere in the source file.
5545 Up to five fields are required:
5549 This is the symbol's name. It may contain any character except
5550 @samp{\000}, so is more general than ordinary symbol names. Some
5551 debuggers used to code arbitrarily complex structures into symbol names
5555 An absolute expression. The symbol's type is set to the low 8 bits of
5556 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5557 and debuggers choke on silly bit patterns.
5560 An absolute expression. The symbol's ``other'' attribute is set to the
5561 low 8 bits of this expression.
5564 An absolute expression. The symbol's descriptor is set to the low 16
5565 bits of this expression.
5568 An absolute expression which becomes the symbol's value.
5571 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5572 or @code{.stabs} statement, the symbol has probably already been created;
5573 you get a half-formed symbol in your object file. This is
5574 compatible with earlier assemblers!
5577 @cindex @code{stabd} directive
5578 @item .stabd @var{type} , @var{other} , @var{desc}
5580 The ``name'' of the symbol generated is not even an empty string.
5581 It is a null pointer, for compatibility. Older assemblers used a
5582 null pointer so they didn't waste space in object files with empty
5585 The symbol's value is set to the location counter,
5586 relocatably. When your program is linked, the value of this symbol
5587 is the address of the location counter when the @code{.stabd} was
5590 @cindex @code{stabn} directive
5591 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5592 The name of the symbol is set to the empty string @code{""}.
5594 @cindex @code{stabs} directive
5595 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5596 All five fields are specified.
5602 @section @code{.string} "@var{str}"
5604 @cindex string, copying to object file
5605 @cindex @code{string} directive
5607 Copy the characters in @var{str} to the object file. You may specify more than
5608 one string to copy, separated by commas. Unless otherwise specified for a
5609 particular machine, the assembler marks the end of each string with a 0 byte.
5610 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5613 @section @code{.struct @var{expression}}
5615 @cindex @code{struct} directive
5616 Switch to the absolute section, and set the section offset to @var{expression},
5617 which must be an absolute expression. You might use this as follows:
5626 This would define the symbol @code{field1} to have the value 0, the symbol
5627 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5628 value 8. Assembly would be left in the absolute section, and you would need to
5629 use a @code{.section} directive of some sort to change to some other section
5630 before further assembly.
5634 @section @code{.subsection @var{name}}
5636 @cindex @code{subsection} directive
5637 @cindex Section Stack
5638 This is one of the ELF section stack manipulation directives. The others are
5639 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5640 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5643 This directive replaces the current subsection with @code{name}. The current
5644 section is not changed. The replaced subsection is put onto the section stack
5645 in place of the then current top of stack subsection.
5650 @section @code{.symver}
5651 @cindex @code{symver} directive
5652 @cindex symbol versioning
5653 @cindex versions of symbols
5654 Use the @code{.symver} directive to bind symbols to specific version nodes
5655 within a source file. This is only supported on ELF platforms, and is
5656 typically used when assembling files to be linked into a shared library.
5657 There are cases where it may make sense to use this in objects to be bound
5658 into an application itself so as to override a versioned symbol from a
5661 For ELF targets, the @code{.symver} directive can be used like this:
5663 .symver @var{name}, @var{name2@@nodename}
5665 If the symbol @var{name} is defined within the file
5666 being assembled, the @code{.symver} directive effectively creates a symbol
5667 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5668 just don't try and create a regular alias is that the @var{@@} character isn't
5669 permitted in symbol names. The @var{name2} part of the name is the actual name
5670 of the symbol by which it will be externally referenced. The name @var{name}
5671 itself is merely a name of convenience that is used so that it is possible to
5672 have definitions for multiple versions of a function within a single source
5673 file, and so that the compiler can unambiguously know which version of a
5674 function is being mentioned. The @var{nodename} portion of the alias should be
5675 the name of a node specified in the version script supplied to the linker when
5676 building a shared library. If you are attempting to override a versioned
5677 symbol from a shared library, then @var{nodename} should correspond to the
5678 nodename of the symbol you are trying to override.
5680 If the symbol @var{name} is not defined within the file being assembled, all
5681 references to @var{name} will be changed to @var{name2@@nodename}. If no
5682 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5685 Another usage of the @code{.symver} directive is:
5687 .symver @var{name}, @var{name2@@@@nodename}
5689 In this case, the symbol @var{name} must exist and be defined within
5690 the file being assembled. It is similar to @var{name2@@nodename}. The
5691 difference is @var{name2@@@@nodename} will also be used to resolve
5692 references to @var{name2} by the linker.
5694 The third usage of the @code{.symver} directive is:
5696 .symver @var{name}, @var{name2@@@@@@nodename}
5698 When @var{name} is not defined within the
5699 file being assembled, it is treated as @var{name2@@nodename}. When
5700 @var{name} is defined within the file being assembled, the symbol
5701 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5706 @section @code{.tag @var{structname}}
5708 @cindex COFF structure debugging
5709 @cindex structure debugging, COFF
5710 @cindex @code{tag} directive
5711 This directive is generated by compilers to include auxiliary debugging
5712 information in the symbol table. It is only permitted inside
5713 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5714 definitions in the symbol table with instances of those structures.
5717 @samp{.tag} is only used when generating COFF format output; when
5718 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5724 @section @code{.text @var{subsection}}
5726 @cindex @code{text} directive
5727 Tells @command{@value{AS}} to assemble the following statements onto the end of
5728 the text subsection numbered @var{subsection}, which is an absolute
5729 expression. If @var{subsection} is omitted, subsection number zero
5733 @section @code{.title "@var{heading}"}
5735 @cindex @code{title} directive
5736 @cindex listing control: title line
5737 Use @var{heading} as the title (second line, immediately after the
5738 source file name and pagenumber) when generating assembly listings.
5740 This directive affects subsequent pages, as well as the current page if
5741 it appears within ten lines of the top of a page.
5745 @section @code{.type}
5747 This directive is used to set the type of a symbol.
5751 @c only print the extra heading if both COFF and ELF are set
5752 @subheading COFF Version
5755 @cindex COFF symbol type
5756 @cindex symbol type, COFF
5757 @cindex @code{type} directive (COFF version)
5758 For COFF targets, this directive is permitted only within
5759 @code{.def}/@code{.endef} pairs. It is used like this:
5765 This records the integer @var{int} as the type attribute of a symbol table
5769 @samp{.type} is associated only with COFF format output; when
5770 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5771 directive but ignores it.
5777 @c only print the extra heading if both COFF and ELF are set
5778 @subheading ELF Version
5781 @cindex ELF symbol type
5782 @cindex symbol type, ELF
5783 @cindex @code{type} directive (ELF version)
5784 For ELF targets, the @code{.type} directive is used like this:
5787 .type @var{name} , @var{type description}
5790 This sets the type of symbol @var{name} to be either a
5791 function symbol or an object symbol. There are five different syntaxes
5792 supported for the @var{type description} field, in order to provide
5793 compatibility with various other assemblers. The syntaxes supported are:
5796 .type <name>,#function
5797 .type <name>,#object
5799 .type <name>,@@function
5800 .type <name>,@@object
5802 .type <name>,%function
5803 .type <name>,%object
5805 .type <name>,"function"
5806 .type <name>,"object"
5808 .type <name> STT_FUNCTION
5809 .type <name> STT_OBJECT
5815 @section @code{.uleb128 @var{expressions}}
5817 @cindex @code{uleb128} directive
5818 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5819 compact, variable length representation of numbers used by the DWARF
5820 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5824 @section @code{.val @var{addr}}
5826 @cindex @code{val} directive
5827 @cindex COFF value attribute
5828 @cindex value attribute, COFF
5829 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5830 records the address @var{addr} as the value attribute of a symbol table
5834 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5835 configured for @code{b.out}, it accepts this directive but ignores it.
5841 @section @code{.version "@var{string}"}
5843 @cindex @code{version} directive
5844 This directive creates a @code{.note} section and places into it an ELF
5845 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5850 @section @code{.vtable_entry @var{table}, @var{offset}}
5852 @cindex @code{vtable_entry}
5853 This directive finds or creates a symbol @code{table} and creates a
5854 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5857 @section @code{.vtable_inherit @var{child}, @var{parent}}
5859 @cindex @code{vtable_inherit}
5860 This directive finds the symbol @code{child} and finds or creates the symbol
5861 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5862 parent whose addend is the value of the child symbol. As a special case the
5863 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5867 @section @code{.weak @var{names}}
5869 @cindex @code{weak} directive
5870 This directive sets the weak attribute on the comma separated list of symbol
5871 @code{names}. If the symbols do not already exist, they will be created.
5873 Weak symbols are supported in COFF as a GNU extension. This directive
5874 sets the weak attribute on the comma separated list of symbol
5875 @code{names}. If the symbols do not already exist, they will be created.
5878 @code{.weak @var{name} [ < = | == > @var{alternate}] [, ...]}
5881 On the PE target, weak aliases are supported natively. Weak aliases
5882 (usually called "weak externals" in PE) are created when an alternate
5883 name is specified. When a weak symbol is linked and the symbol is not
5884 defined, the weak symbol becomes an alias for the alternate symbol. If
5885 one equal sign is used, the linker searches for defined symbols within
5886 other objects and libraries. This is the usual mode, historically
5887 called "lazy externals." Otherwise, when two equal signs are used,
5888 the linker searches for defined symbols only within other objects.
5890 Non-alias weak symbols are supported on PE as a GNU extension.
5893 @section @code{.word @var{expressions}}
5895 @cindex @code{word} directive
5896 This directive expects zero or more @var{expressions}, of any section,
5897 separated by commas.
5900 For each expression, @command{@value{AS}} emits a 32-bit number.
5903 For each expression, @command{@value{AS}} emits a 16-bit number.
5908 The size of the number emitted, and its byte order,
5909 depend on what target computer the assembly is for.
5912 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5913 @c happen---32-bit addressability, period; no long/short jumps.
5914 @ifset DIFF-TBL-KLUGE
5915 @cindex difference tables altered
5916 @cindex altered difference tables
5918 @emph{Warning: Special Treatment to support Compilers}
5922 Machines with a 32-bit address space, but that do less than 32-bit
5923 addressing, require the following special treatment. If the machine of
5924 interest to you does 32-bit addressing (or doesn't require it;
5925 @pxref{Machine Dependencies}), you can ignore this issue.
5928 In order to assemble compiler output into something that works,
5929 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5930 Directives of the form @samp{.word sym1-sym2} are often emitted by
5931 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5932 directive of the form @samp{.word sym1-sym2}, and the difference between
5933 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5934 creates a @dfn{secondary jump table}, immediately before the next label.
5935 This secondary jump table is preceded by a short-jump to the
5936 first byte after the secondary table. This short-jump prevents the flow
5937 of control from accidentally falling into the new table. Inside the
5938 table is a long-jump to @code{sym2}. The original @samp{.word}
5939 contains @code{sym1} minus the address of the long-jump to
5942 If there were several occurrences of @samp{.word sym1-sym2} before the
5943 secondary jump table, all of them are adjusted. If there was a
5944 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5945 long-jump to @code{sym4} is included in the secondary jump table,
5946 and the @code{.word} directives are adjusted to contain @code{sym3}
5947 minus the address of the long-jump to @code{sym4}; and so on, for as many
5948 entries in the original jump table as necessary.
5951 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5952 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5953 assembly language programmers.
5956 @c end DIFF-TBL-KLUGE
5959 @section Deprecated Directives
5961 @cindex deprecated directives
5962 @cindex obsolescent directives
5963 One day these directives won't work.
5964 They are included for compatibility with older assemblers.
5971 @node Machine Dependencies
5972 @chapter Machine Dependent Features
5974 @cindex machine dependencies
5975 The machine instruction sets are (almost by definition) different on
5976 each machine where @command{@value{AS}} runs. Floating point representations
5977 vary as well, and @command{@value{AS}} often supports a few additional
5978 directives or command-line options for compatibility with other
5979 assemblers on a particular platform. Finally, some versions of
5980 @command{@value{AS}} support special pseudo-instructions for branch
5983 This chapter discusses most of these differences, though it does not
5984 include details on any machine's instruction set. For details on that
5985 subject, see the hardware manufacturer's manual.
5989 * AMD29K-Dependent:: AMD 29K Dependent Features
5992 * Alpha-Dependent:: Alpha Dependent Features
5995 * ARC-Dependent:: ARC Dependent Features
5998 * ARM-Dependent:: ARM Dependent Features
6001 * CRIS-Dependent:: CRIS Dependent Features
6004 * D10V-Dependent:: D10V Dependent Features
6007 * D30V-Dependent:: D30V Dependent Features
6010 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6013 * H8/500-Dependent:: Renesas H8/500 Dependent Features
6016 * HPPA-Dependent:: HPPA Dependent Features
6019 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
6022 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
6025 * i860-Dependent:: Intel 80860 Dependent Features
6028 * i960-Dependent:: Intel 80960 Dependent Features
6031 * IP2K-Dependent:: IP2K Dependent Features
6034 * M32R-Dependent:: M32R Dependent Features
6037 * M68K-Dependent:: M680x0 Dependent Features
6040 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
6043 * M88K-Dependent:: M880x0 Dependent Features
6046 * MIPS-Dependent:: MIPS Dependent Features
6049 * MMIX-Dependent:: MMIX Dependent Features
6052 * MSP430-Dependent:: MSP430 Dependent Features
6055 * SH-Dependent:: Renesas / SuperH SH Dependent Features
6056 * SH64-Dependent:: SuperH SH64 Dependent Features
6059 * PDP-11-Dependent:: PDP-11 Dependent Features
6062 * PJ-Dependent:: picoJava Dependent Features
6065 * PPC-Dependent:: PowerPC Dependent Features
6068 * Sparc-Dependent:: SPARC Dependent Features
6071 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
6074 * V850-Dependent:: V850 Dependent Features
6077 * Xtensa-Dependent:: Xtensa Dependent Features
6080 * Z8000-Dependent:: Z8000 Dependent Features
6083 * Vax-Dependent:: VAX Dependent Features
6090 @c The following major nodes are *sections* in the GENERIC version, *chapters*
6091 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
6092 @c peculiarity: to preserve cross-references, there must be a node called
6093 @c "Machine Dependencies". Hence the conditional nodenames in each
6094 @c major node below. Node defaulting in makeinfo requires adjacency of
6095 @c node and sectioning commands; hence the repetition of @chapter BLAH
6096 @c in both conditional blocks.
6099 @include c-a29k.texi
6103 @include c-alpha.texi
6115 @include c-cris.texi
6120 @node Machine Dependencies
6121 @chapter Machine Dependent Features
6123 The machine instruction sets are different on each Renesas chip family,
6124 and there are also some syntax differences among the families. This
6125 chapter describes the specific @command{@value{AS}} features for each
6129 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6130 * H8/500-Dependent:: Renesas H8/500 Dependent Features
6131 * SH-Dependent:: Renesas SH Dependent Features
6138 @include c-d10v.texi
6142 @include c-d30v.texi
6146 @include c-h8300.texi
6150 @include c-h8500.texi
6154 @include c-hppa.texi
6158 @include c-i370.texi
6162 @include c-i386.texi
6166 @include c-i860.texi
6170 @include c-i960.texi
6174 @include c-ia64.texi
6178 @include c-ip2k.texi
6182 @include c-m32r.texi
6186 @include c-m68k.texi
6190 @include c-m68hc11.texi
6194 @include c-m88k.texi
6198 @include c-mips.texi
6202 @include c-mmix.texi
6206 @include c-msp430.texi
6210 @include c-ns32k.texi
6214 @include c-pdp11.texi
6227 @include c-sh64.texi
6231 @include c-sparc.texi
6235 @include c-tic54x.texi
6247 @include c-v850.texi
6251 @include c-xtensa.texi
6255 @c reverse effect of @down at top of generic Machine-Dep chapter
6259 @node Reporting Bugs
6260 @chapter Reporting Bugs
6261 @cindex bugs in assembler
6262 @cindex reporting bugs in assembler
6264 Your bug reports play an essential role in making @command{@value{AS}} reliable.
6266 Reporting a bug may help you by bringing a solution to your problem, or it may
6267 not. But in any case the principal function of a bug report is to help the
6268 entire community by making the next version of @command{@value{AS}} work better.
6269 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
6271 In order for a bug report to serve its purpose, you must include the
6272 information that enables us to fix the bug.
6275 * Bug Criteria:: Have you found a bug?
6276 * Bug Reporting:: How to report bugs
6280 @section Have You Found a Bug?
6281 @cindex bug criteria
6283 If you are not sure whether you have found a bug, here are some guidelines:
6286 @cindex fatal signal
6287 @cindex assembler crash
6288 @cindex crash of assembler
6290 If the assembler gets a fatal signal, for any input whatever, that is a
6291 @command{@value{AS}} bug. Reliable assemblers never crash.
6293 @cindex error on valid input
6295 If @command{@value{AS}} produces an error message for valid input, that is a bug.
6297 @cindex invalid input
6299 If @command{@value{AS}} does not produce an error message for invalid input, that
6300 is a bug. However, you should note that your idea of ``invalid input'' might
6301 be our idea of ``an extension'' or ``support for traditional practice''.
6304 If you are an experienced user of assemblers, your suggestions for improvement
6305 of @command{@value{AS}} are welcome in any case.
6309 @section How to Report Bugs
6311 @cindex assembler bugs, reporting
6313 A number of companies and individuals offer support for @sc{gnu} products. If
6314 you obtained @command{@value{AS}} from a support organization, we recommend you
6315 contact that organization first.
6317 You can find contact information for many support companies and
6318 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
6321 In any event, we also recommend that you send bug reports for @command{@value{AS}}
6322 to @samp{bug-binutils@@gnu.org}.
6324 The fundamental principle of reporting bugs usefully is this:
6325 @strong{report all the facts}. If you are not sure whether to state a
6326 fact or leave it out, state it!
6328 Often people omit facts because they think they know what causes the problem
6329 and assume that some details do not matter. Thus, you might assume that the
6330 name of a symbol you use in an example does not matter. Well, probably it does
6331 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
6332 happens to fetch from the location where that name is stored in memory;
6333 perhaps, if the name were different, the contents of that location would fool
6334 the assembler into doing the right thing despite the bug. Play it safe and
6335 give a specific, complete example. That is the easiest thing for you to do,
6336 and the most helpful.
6338 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
6339 it is new to us. Therefore, always write your bug reports on the assumption
6340 that the bug has not been reported previously.
6342 Sometimes people give a few sketchy facts and ask, ``Does this ring a
6343 bell?'' This cannot help us fix a bug, so it is basically useless. We
6344 respond by asking for enough details to enable us to investigate.
6345 You might as well expedite matters by sending them to begin with.
6347 To enable us to fix the bug, you should include all these things:
6351 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
6352 it with the @samp{--version} argument.
6354 Without this, we will not know whether there is any point in looking for
6355 the bug in the current version of @command{@value{AS}}.
6358 Any patches you may have applied to the @command{@value{AS}} source.
6361 The type of machine you are using, and the operating system name and
6365 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
6369 The command arguments you gave the assembler to assemble your example and
6370 observe the bug. To guarantee you will not omit something important, list them
6371 all. A copy of the Makefile (or the output from make) is sufficient.
6373 If we were to try to guess the arguments, we would probably guess wrong
6374 and then we might not encounter the bug.
6377 A complete input file that will reproduce the bug. If the bug is observed when
6378 the assembler is invoked via a compiler, send the assembler source, not the
6379 high level language source. Most compilers will produce the assembler source
6380 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
6381 the options @samp{-v --save-temps}; this will save the assembler source in a
6382 file with an extension of @file{.s}, and also show you exactly how
6383 @command{@value{AS}} is being run.
6386 A description of what behavior you observe that you believe is
6387 incorrect. For example, ``It gets a fatal signal.''
6389 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
6390 will certainly notice it. But if the bug is incorrect output, we might not
6391 notice unless it is glaringly wrong. You might as well not give us a chance to
6394 Even if the problem you experience is a fatal signal, you should still say so
6395 explicitly. Suppose something strange is going on, such as, your copy of
6396 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
6397 library on your system. (This has happened!) Your copy might crash and ours
6398 would not. If you told us to expect a crash, then when ours fails to crash, we
6399 would know that the bug was not happening for us. If you had not told us to
6400 expect a crash, then we would not be able to draw any conclusion from our
6404 If you wish to suggest changes to the @command{@value{AS}} source, send us context
6405 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
6406 option. Always send diffs from the old file to the new file. If you even
6407 discuss something in the @command{@value{AS}} source, refer to it by context, not
6410 The line numbers in our development sources will not match those in your
6411 sources. Your line numbers would convey no useful information to us.
6414 Here are some things that are not necessary:
6418 A description of the envelope of the bug.
6420 Often people who encounter a bug spend a lot of time investigating
6421 which changes to the input file will make the bug go away and which
6422 changes will not affect it.
6424 This is often time consuming and not very useful, because the way we
6425 will find the bug is by running a single example under the debugger
6426 with breakpoints, not by pure deduction from a series of examples.
6427 We recommend that you save your time for something else.
6429 Of course, if you can find a simpler example to report @emph{instead}
6430 of the original one, that is a convenience for us. Errors in the
6431 output will be easier to spot, running under the debugger will take
6432 less time, and so on.
6434 However, simplification is not vital; if you do not want to do this,
6435 report the bug anyway and send us the entire test case you used.
6438 A patch for the bug.
6440 A patch for the bug does help us if it is a good one. But do not omit
6441 the necessary information, such as the test case, on the assumption that
6442 a patch is all we need. We might see problems with your patch and decide
6443 to fix the problem another way, or we might not understand it at all.
6445 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6446 construct an example that will make the program follow a certain path through
6447 the code. If you do not send us the example, we will not be able to construct
6448 one, so we will not be able to verify that the bug is fixed.
6450 And if we cannot understand what bug you are trying to fix, or why your
6451 patch should be an improvement, we will not install it. A test case will
6452 help us to understand.
6455 A guess about what the bug is or what it depends on.
6457 Such guesses are usually wrong. Even we cannot guess right about such
6458 things without first using the debugger to find the facts.
6461 @node Acknowledgements
6462 @chapter Acknowledgements
6464 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6465 it is not meant as a slight. We just don't know about it. Send mail to the
6466 maintainer, and we'll correct the situation. Currently
6468 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6470 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6473 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6474 information and the 68k series machines, most of the preprocessing pass, and
6475 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6477 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6478 many bug fixes, including merging support for several processors, breaking GAS
6479 up to handle multiple object file format back ends (including heavy rewrite,
6480 testing, an integration of the coff and b.out back ends), adding configuration
6481 including heavy testing and verification of cross assemblers and file splits
6482 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6483 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6484 port (including considerable amounts of reverse engineering), a SPARC opcode
6485 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6486 assertions and made them work, much other reorganization, cleanup, and lint.
6488 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6489 in format-specific I/O modules.
6491 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6492 has done much work with it since.
6494 The Intel 80386 machine description was written by Eliot Dresselhaus.
6496 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6498 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6499 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6501 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6502 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6503 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6504 support a.out format.
6506 Support for the Zilog Z8k and Renesas H8/300 and H8/500 processors (tc-z8k,
6507 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6508 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6509 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6512 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6513 simplified the configuration of which versions accept which directives. He
6514 updated the 68k machine description so that Motorola's opcodes always produced
6515 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
6516 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6517 cross-compilation support, and one bug in relaxation that took a week and
6518 required the proverbial one-bit fix.
6520 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6521 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6522 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6523 PowerPC assembler, and made a few other minor patches.
6525 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6527 Hewlett-Packard contributed support for the HP9000/300.
6529 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6530 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6531 formats). This work was supported by both the Center for Software Science at
6532 the University of Utah and Cygnus Support.
6534 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6535 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6536 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6537 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6538 and some initial 64-bit support).
6540 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
6542 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6543 support for openVMS/Alpha.
6545 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6548 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
6549 Inc. added support for Xtensa processors.
6551 Several engineers at Cygnus Support have also provided many small bug fixes and
6552 configuration enhancements.
6554 Many others have contributed large or small bugfixes and enhancements. If
6555 you have contributed significant work and are not mentioned on this list, and
6556 want to be, let us know. Some of the history has been lost; we are not
6557 intentionally leaving anyone out.
projects / deliverable / binutils-gdb.git / blob