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{-k}]
275 @emph{Target CRIS options:}
276 [@b{--underscore} | @b{--no-underscore}]
278 [@b{--emulation=criself} | @b{--emulation=crisaout}]
279 [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}]
280 @c Deprecated -- deliberately not documented.
285 @emph{Target D10V options:}
290 @emph{Target D30V options:}
291 [@b{-O}|@b{-n}|@b{-N}]
294 @c Renesas family chips have no machine-dependent assembler options
297 @c HPPA has no machine-dependent assembler options (yet).
301 @emph{Target i386 options:}
302 [@b{--32}|@b{--64}] [@b{-n}]
306 @emph{Target i960 options:}
307 @c see md_parse_option in tc-i960.c
308 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
310 [@b{-b}] [@b{-no-relax}]
314 @emph{Target IA-64 options:}
315 [@b{-mconstant-gp}|@b{-mauto-pic}]
316 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
318 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
322 @emph{Target IP2K options:}
323 [@b{-mip2022}|@b{-mip2022ext}]
327 @emph{Target M32R options:}
328 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
333 @emph{Target M680X0 options:}
334 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
338 @emph{Target M68HC11 options:}
339 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}]
340 [@b{-mshort}|@b{-mlong}]
341 [@b{-mshort-double}|@b{-mlong-double}]
342 [@b{--force-long-branchs}] [@b{--short-branchs}]
343 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
344 [@b{--print-opcodes}] [@b{--generate-example}]
348 @emph{Target MCORE options:}
349 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
350 [@b{-mcpu=[210|340]}]
354 @emph{Target MIPS options:}
355 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
356 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
357 [@b{-non_shared}] [@b{-xgot}]
358 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
359 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
360 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
361 [@b{-mips64}] [@b{-mips64r2}]
362 [@b{-construct-floats}] [@b{-no-construct-floats}]
363 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
364 [@b{-mfix7000}] [@b{-mno-fix7000}]
365 [@b{-mips16}] [@b{-no-mips16}]
366 [@b{-mips3d}] [@b{-no-mips3d}]
367 [@b{-mdmx}] [@b{-no-mdmx}]
368 [@b{-mdebug}] [@b{-no-mdebug}]
369 [@b{-mpdr}] [@b{-mno-pdr}]
373 @emph{Target MMIX options:}
374 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
375 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
376 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
377 [@b{--linker-allocated-gregs}]
381 @emph{Target PDP11 options:}
382 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
383 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
384 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
388 @emph{Target picoJava options:}
393 @emph{Target PowerPC options:}
394 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
395 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
396 @b{-mbooke32}|@b{-mbooke64}]
397 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
398 [@b{-mregnames}|@b{-mno-regnames}]
399 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
400 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
401 [@b{-msolaris}|@b{-mno-solaris}]
405 @emph{Target SPARC options:}
406 @c The order here is important. See c-sparc.texi.
407 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
408 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
409 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
414 @emph{Target TIC54X options:}
415 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
416 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
419 @c Z8000 has no machine-dependent assembler options
423 @emph{Target Xtensa options:}
424 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
425 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
426 [@b{--[no-]transform}]
427 [@b{--rename-section} @var{oldname}=@var{newname}]
436 Turn on listings, in any of a variety of ways:
440 omit false conditionals
443 omit debugging directives
446 include high-level source
452 include macro expansions
455 omit forms processing
461 set the name of the listing file
464 You may combine these options; for example, use @samp{-aln} for assembly
465 listing without forms processing. The @samp{=file} option, if used, must be
466 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
469 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
472 Ignored. This option is accepted for script compatibility with calls to
475 @item --defsym @var{sym}=@var{value}
476 Define the symbol @var{sym} to be @var{value} before assembling the input file.
477 @var{value} must be an integer constant. As in C, a leading @samp{0x}
478 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
481 ``fast''---skip whitespace and comment preprocessing (assume source is
486 Generate debugging information for each assembler source line using whichever
487 debug format is preferred by the target. This currently means either STABS,
491 Generate stabs debugging information for each assembler line. This
492 may help debugging assembler code, if the debugger can handle it.
495 Generate stabs debugging information for each assembler line, with GNU
496 extensions that probably only gdb can handle, and that could make other
497 debuggers crash or refuse to read your program. This
498 may help debugging assembler code. Currently the only GNU extension is
499 the location of the current working directory at assembling time.
502 Generate DWARF2 debugging information for each assembler line. This
503 may help debugging assembler code, if the debugger can handle it. Note---this
504 option is only supported by some targets, not all of them.
507 Print a summary of the command line options and exit.
510 Print a summary of all target specific options and exit.
513 Add directory @var{dir} to the search list for @code{.include} directives.
516 Don't warn about signed overflow.
519 @ifclear DIFF-TBL-KLUGE
520 This option is accepted but has no effect on the @value{TARGET} family.
522 @ifset DIFF-TBL-KLUGE
523 Issue warnings when difference tables altered for long displacements.
528 Keep (in the symbol table) local symbols. On traditional a.out systems
529 these start with @samp{L}, but different systems have different local
532 @item --listing-lhs-width=@var{number}
533 Set the maximum width, in words, of the output data column for an assembler
534 listing to @var{number}.
536 @item --listing-lhs-width2=@var{number}
537 Set the maximum width, in words, of the output data column for continuation
538 lines in an assembler listing to @var{number}.
540 @item --listing-rhs-width=@var{number}
541 Set the maximum width of an input source line, as displayed in a listing, to
544 @item --listing-cont-lines=@var{number}
545 Set the maximum number of lines printed in a listing for a single line of input
548 @item -o @var{objfile}
549 Name the object-file output from @command{@value{AS}} @var{objfile}.
552 Fold the data section into the text section.
555 Print the maximum space (in bytes) and total time (in seconds) used by
558 @item --strip-local-absolute
559 Remove local absolute symbols from the outgoing symbol table.
563 Print the @command{as} version.
566 Print the @command{as} version and exit.
570 Suppress warning messages.
572 @item --fatal-warnings
573 Treat warnings as errors.
576 Don't suppress warning messages or treat them as errors.
585 Generate an object file even after errors.
587 @item -- | @var{files} @dots{}
588 Standard input, or source files to assemble.
593 The following options are available when @value{AS} is configured for
598 This option selects the core processor variant.
600 Select either big-endian (-EB) or little-endian (-EL) output.
605 The following options are available when @value{AS} is configured for the ARM
609 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
610 Specify which ARM processor variant is the target.
611 @item -march=@var{architecture}[+@var{extension}@dots{}]
612 Specify which ARM architecture variant is used by the target.
613 @item -mfpu=@var{floating-point-format}
614 Select which Floating Point architecture is the target.
615 @item -mfloat-abi=@var{abi}
616 Select which floating point ABI is in use.
618 Enable Thumb only instruction decoding.
619 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
620 Select which procedure calling convention is in use.
622 Select either big-endian (-EB) or little-endian (-EL) output.
623 @item -mthumb-interwork
624 Specify that the code has been generated with interworking between Thumb and
627 Specify that PIC code has been generated.
632 See the info pages for documentation of the CRIS-specific options.
636 The following options are available when @value{AS} is configured for
639 @cindex D10V optimization
640 @cindex optimization, D10V
642 Optimize output by parallelizing instructions.
647 The following options are available when @value{AS} is configured for a D30V
650 @cindex D30V optimization
651 @cindex optimization, D30V
653 Optimize output by parallelizing instructions.
657 Warn when nops are generated.
659 @cindex D30V nops after 32-bit multiply
661 Warn when a nop after a 32-bit multiply instruction is generated.
666 The following options are available when @value{AS} is configured for the
667 Intel 80960 processor.
670 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
671 Specify which variant of the 960 architecture is the target.
674 Add code to collect statistics about branches taken.
677 Do not alter compare-and-branch instructions for long displacements;
684 The following options are available when @value{AS} is configured for the
690 Specifies that the extended IP2022 instructions are allowed.
693 Restores the default behaviour, which restricts the permitted instructions to
694 just the basic IP2022 ones.
700 The following options are available when @value{AS} is configured for the
701 Renesas M32R (formerly Mitsubishi M32R) series.
706 Specify which processor in the M32R family is the target. The default
707 is normally the M32R, but this option changes it to the M32RX.
709 @item --warn-explicit-parallel-conflicts or --Wp
710 Produce warning messages when questionable parallel constructs are
713 @item --no-warn-explicit-parallel-conflicts or --Wnp
714 Do not produce warning messages when questionable parallel constructs are
721 The following options are available when @value{AS} is configured for the
722 Motorola 68000 series.
727 Shorten references to undefined symbols, to one word instead of two.
729 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
730 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
731 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
732 Specify what processor in the 68000 family is the target. The default
733 is normally the 68020, but this can be changed at configuration time.
735 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
736 The target machine does (or does not) have a floating-point coprocessor.
737 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
738 the basic 68000 is not compatible with the 68881, a combination of the
739 two can be specified, since it's possible to do emulation of the
740 coprocessor instructions with the main processor.
742 @item -m68851 | -mno-68851
743 The target machine does (or does not) have a memory-management
744 unit coprocessor. The default is to assume an MMU for 68020 and up.
751 For details about the PDP-11 machine dependent features options,
752 see @ref{PDP-11-Options}.
755 @item -mpic | -mno-pic
756 Generate position-independent (or position-dependent) code. The
757 default is @option{-mpic}.
760 @itemx -mall-extensions
761 Enable all instruction set extensions. This is the default.
763 @item -mno-extensions
764 Disable all instruction set extensions.
766 @item -m@var{extension} | -mno-@var{extension}
767 Enable (or disable) a particular instruction set extension.
770 Enable the instruction set extensions supported by a particular CPU, and
771 disable all other extensions.
773 @item -m@var{machine}
774 Enable the instruction set extensions supported by a particular machine
775 model, and disable all other extensions.
781 The following options are available when @value{AS} is configured for
782 a picoJava processor.
786 @cindex PJ endianness
787 @cindex endianness, PJ
788 @cindex big endian output, PJ
790 Generate ``big endian'' format output.
792 @cindex little endian output, PJ
794 Generate ``little endian'' format output.
800 The following options are available when @value{AS} is configured for the
801 Motorola 68HC11 or 68HC12 series.
805 @item -m68hc11 | -m68hc12 | -m68hcs12
806 Specify what processor is the target. The default is
807 defined by the configuration option when building the assembler.
810 Specify to use the 16-bit integer ABI.
813 Specify to use the 32-bit integer ABI.
816 Specify to use the 32-bit double ABI.
819 Specify to use the 64-bit double ABI.
821 @item --force-long-branchs
822 Relative branches are turned into absolute ones. This concerns
823 conditional branches, unconditional branches and branches to a
826 @item -S | --short-branchs
827 Do not turn relative branchs into absolute ones
828 when the offset is out of range.
830 @item --strict-direct-mode
831 Do not turn the direct addressing mode into extended addressing mode
832 when the instruction does not support direct addressing mode.
834 @item --print-insn-syntax
835 Print the syntax of instruction in case of error.
837 @item --print-opcodes
838 print the list of instructions with syntax and then exit.
840 @item --generate-example
841 print an example of instruction for each possible instruction and then exit.
842 This option is only useful for testing @command{@value{AS}}.
848 The following options are available when @command{@value{AS}} is configured
849 for the SPARC architecture:
852 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
853 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
854 Explicitly select a variant of the SPARC architecture.
856 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
857 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
859 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
860 UltraSPARC extensions.
862 @item -xarch=v8plus | -xarch=v8plusa
863 For compatibility with the Solaris v9 assembler. These options are
864 equivalent to -Av8plus and -Av8plusa, respectively.
867 Warn when the assembler switches to another architecture.
872 The following options are available when @value{AS} is configured for the 'c54x
877 Enable extended addressing mode. All addresses and relocations will assume
878 extended addressing (usually 23 bits).
879 @item -mcpu=@var{CPU_VERSION}
880 Sets the CPU version being compiled for.
881 @item -merrors-to-file @var{FILENAME}
882 Redirect error output to a file, for broken systems which don't support such
883 behaviour in the shell.
888 The following options are available when @value{AS} is configured for
889 a @sc{mips} processor.
893 This option sets the largest size of an object that can be referenced
894 implicitly with the @code{gp} register. It is only accepted for targets that
895 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
897 @cindex MIPS endianness
898 @cindex endianness, MIPS
899 @cindex big endian output, MIPS
901 Generate ``big endian'' format output.
903 @cindex little endian output, MIPS
905 Generate ``little endian'' format output.
917 Generate code for a particular @sc{mips} Instruction Set Architecture level.
918 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
919 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
920 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
921 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and
923 correspond to generic
924 @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64},
925 and @samp{MIPS64 Release 2}
926 ISA processors, respectively.
928 @item -march=@var{CPU}
929 Generate code for a particular @sc{mips} cpu.
931 @item -mtune=@var{cpu}
932 Schedule and tune for a particular @sc{mips} cpu.
936 Cause nops to be inserted if the read of the destination register
937 of an mfhi or mflo instruction occurs in the following two instructions.
941 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
942 section instead of the standard ELF .stabs sections.
946 Control generation of @code{.pdr} sections.
950 The register sizes are normally inferred from the ISA and ABI, but these
951 flags force a certain group of registers to be treated as 32 bits wide at
952 all times. @samp{-mgp32} controls the size of general-purpose registers
953 and @samp{-mfp32} controls the size of floating-point registers.
957 Generate code for the MIPS 16 processor. This is equivalent to putting
958 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
959 turns off this option.
963 Generate code for the MIPS-3D Application Specific Extension.
964 This tells the assembler to accept MIPS-3D instructions.
965 @samp{-no-mips3d} turns off this option.
969 Generate code for the MDMX Application Specific Extension.
970 This tells the assembler to accept MDMX instructions.
971 @samp{-no-mdmx} turns off this option.
973 @item --construct-floats
974 @itemx --no-construct-floats
975 The @samp{--no-construct-floats} option disables the construction of
976 double width floating point constants by loading the two halves of the
977 value into the two single width floating point registers that make up
978 the double width register. By default @samp{--construct-floats} is
979 selected, allowing construction of these floating point constants.
982 @item --emulation=@var{name}
983 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
984 for some other target, in all respects, including output format (choosing
985 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
986 debugging information or store symbol table information, and default
987 endianness. The available configuration names are: @samp{mipsecoff},
988 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
989 @samp{mipsbelf}. The first two do not alter the default endianness from that
990 of the primary target for which the assembler was configured; the others change
991 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
992 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
993 selection in any case.
995 This option is currently supported only when the primary target
996 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
997 Furthermore, the primary target or others specified with
998 @samp{--enable-targets=@dots{}} at configuration time must include support for
999 the other format, if both are to be available. For example, the Irix 5
1000 configuration includes support for both.
1002 Eventually, this option will support more configurations, with more
1003 fine-grained control over the assembler's behavior, and will be supported for
1007 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1014 Control how to deal with multiplication overflow and division by zero.
1015 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1016 (and only work for Instruction Set Architecture level 2 and higher);
1017 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1021 When this option is used, @command{@value{AS}} will issue a warning every
1022 time it generates a nop instruction from a macro.
1027 The following options are available when @value{AS} is configured for
1033 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1034 The command line option @samp{-nojsri2bsr} can be used to disable it.
1038 Enable or disable the silicon filter behaviour. By default this is disabled.
1039 The default can be overridden by the @samp{-sifilter} command line option.
1042 Alter jump instructions for long displacements.
1044 @item -mcpu=[210|340]
1045 Select the cpu type on the target hardware. This controls which instructions
1049 Assemble for a big endian target.
1052 Assemble for a little endian target.
1058 See the info pages for documentation of the MMIX-specific options.
1062 The following options are available when @value{AS} is configured for
1063 an Xtensa processor.
1066 @item --text-section-literals | --no-text-section-literals
1067 With @option{--text-@-section-@-literals}, literal pools are interspersed
1068 in the text section. The default is
1069 @option{--no-@-text-@-section-@-literals}, which places literals in a
1070 separate section in the output file. These options only affect literals
1071 referenced via PC-relative @code{L32R} instructions; literals for
1072 absolute mode @code{L32R} instructions are handled separately.
1074 @item --absolute-literals | --no-absolute-literals
1075 Indicate to the assembler whether @code{L32R} instructions use absolute
1076 or PC-relative addressing. The default is to assume absolute addressing
1077 if the Xtensa processor includes the absolute @code{L32R} addressing
1078 option. Otherwise, only the PC-relative @code{L32R} mode can be used.
1080 @item --target-align | --no-target-align
1081 Enable or disable automatic alignment to reduce branch penalties at the
1082 expense of some code density. The default is @option{--target-@-align}.
1084 @item --longcalls | --no-longcalls
1085 Enable or disable transformation of call instructions to allow calls
1086 across a greater range of addresses. The default is
1087 @option{--no-@-longcalls}.
1089 @item --transform | --no-transform
1090 Enable or disable all assembler transformations of Xtensa instructions.
1091 The default is @option{--transform};
1092 @option{--no-transform} should be used only in the rare cases when the
1093 instructions must be exactly as specified in the assembly source.
1100 * Manual:: Structure of this Manual
1101 * GNU Assembler:: The GNU Assembler
1102 * Object Formats:: Object File Formats
1103 * Command Line:: Command Line
1104 * Input Files:: Input Files
1105 * Object:: Output (Object) File
1106 * Errors:: Error and Warning Messages
1110 @section Structure of this Manual
1112 @cindex manual, structure and purpose
1113 This manual is intended to describe what you need to know to use
1114 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1115 notation for symbols, constants, and expressions; the directives that
1116 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1119 We also cover special features in the @value{TARGET}
1120 configuration of @command{@value{AS}}, including assembler directives.
1123 This manual also describes some of the machine-dependent features of
1124 various flavors of the assembler.
1127 @cindex machine instructions (not covered)
1128 On the other hand, this manual is @emph{not} intended as an introduction
1129 to programming in assembly language---let alone programming in general!
1130 In a similar vein, we make no attempt to introduce the machine
1131 architecture; we do @emph{not} describe the instruction set, standard
1132 mnemonics, registers or addressing modes that are standard to a
1133 particular architecture.
1135 You may want to consult the manufacturer's
1136 machine architecture manual for this information.
1140 For information on the H8/300 machine instruction set, see @cite{H8/300
1141 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1142 Programming Manual} (Renesas).
1145 For information on the H8/500 machine instruction set, see @cite{H8/500
1146 Series Programming Manual} (Renesas M21T001).
1149 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1150 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1151 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1152 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1155 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1159 @c I think this is premature---doc@cygnus.com, 17jan1991
1161 Throughout this manual, we assume that you are running @dfn{GNU},
1162 the portable operating system from the @dfn{Free Software
1163 Foundation, Inc.}. This restricts our attention to certain kinds of
1164 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1165 once this assumption is granted examples and definitions need less
1168 @command{@value{AS}} is part of a team of programs that turn a high-level
1169 human-readable series of instructions into a low-level
1170 computer-readable series of instructions. Different versions of
1171 @command{@value{AS}} are used for different kinds of computer.
1174 @c There used to be a section "Terminology" here, which defined
1175 @c "contents", "byte", "word", and "long". Defining "word" to any
1176 @c particular size is confusing when the .word directive may generate 16
1177 @c bits on one machine and 32 bits on another; in general, for the user
1178 @c version of this manual, none of these terms seem essential to define.
1179 @c They were used very little even in the former draft of the manual;
1180 @c this draft makes an effort to avoid them (except in names of
1184 @section The GNU Assembler
1186 @c man begin DESCRIPTION
1188 @sc{gnu} @command{as} is really a family of assemblers.
1190 This manual describes @command{@value{AS}}, a member of that family which is
1191 configured for the @value{TARGET} architectures.
1193 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1194 should find a fairly similar environment when you use it on another
1195 architecture. Each version has much in common with the others,
1196 including object file formats, most assembler directives (often called
1197 @dfn{pseudo-ops}) and assembler syntax.@refill
1199 @cindex purpose of @sc{gnu} assembler
1200 @command{@value{AS}} is primarily intended to assemble the output of the
1201 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1202 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1203 assemble correctly everything that other assemblers for the same
1204 machine would assemble.
1206 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1209 @c This remark should appear in generic version of manual; assumption
1210 @c here is that generic version sets M680x0.
1211 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1212 assembler for the same architecture; for example, we know of several
1213 incompatible versions of 680x0 assembly language syntax.
1218 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1219 program in one pass of the source file. This has a subtle impact on the
1220 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1222 @node Object Formats
1223 @section Object File Formats
1225 @cindex object file format
1226 The @sc{gnu} assembler can be configured to produce several alternative
1227 object file formats. For the most part, this does not affect how you
1228 write assembly language programs; but directives for debugging symbols
1229 are typically different in different file formats. @xref{Symbol
1230 Attributes,,Symbol Attributes}.
1233 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1234 @value{OBJ-NAME} format object files.
1236 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1238 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1239 @code{a.out} or COFF format object files.
1242 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1243 @code{b.out} or COFF format object files.
1246 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1247 SOM or ELF format object files.
1252 @section Command Line
1254 @cindex command line conventions
1256 After the program name @command{@value{AS}}, the command line may contain
1257 options and file names. Options may appear in any order, and may be
1258 before, after, or between file names. The order of file names is
1261 @cindex standard input, as input file
1263 @file{--} (two hyphens) by itself names the standard input file
1264 explicitly, as one of the files for @command{@value{AS}} to assemble.
1266 @cindex options, command line
1267 Except for @samp{--} any command line argument that begins with a
1268 hyphen (@samp{-}) is an option. Each option changes the behavior of
1269 @command{@value{AS}}. No option changes the way another option works. An
1270 option is a @samp{-} followed by one or more letters; the case of
1271 the letter is important. All options are optional.
1273 Some options expect exactly one file name to follow them. The file
1274 name may either immediately follow the option's letter (compatible
1275 with older assemblers) or it may be the next command argument (@sc{gnu}
1276 standard). These two command lines are equivalent:
1279 @value{AS} -o my-object-file.o mumble.s
1280 @value{AS} -omy-object-file.o mumble.s
1284 @section Input Files
1287 @cindex source program
1288 @cindex files, input
1289 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1290 describe the program input to one run of @command{@value{AS}}. The program may
1291 be in one or more files; how the source is partitioned into files
1292 doesn't change the meaning of the source.
1294 @c I added "con" prefix to "catenation" just to prove I can overcome my
1295 @c APL training... doc@cygnus.com
1296 The source program is a concatenation of the text in all the files, in the
1299 @c man begin DESCRIPTION
1300 Each time you run @command{@value{AS}} it assembles exactly one source
1301 program. The source program is made up of one or more files.
1302 (The standard input is also a file.)
1304 You give @command{@value{AS}} a command line that has zero or more input file
1305 names. The input files are read (from left file name to right). A
1306 command line argument (in any position) that has no special meaning
1307 is taken to be an input file name.
1309 If you give @command{@value{AS}} no file names it attempts to read one input file
1310 from the @command{@value{AS}} standard input, which is normally your terminal. You
1311 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1314 Use @samp{--} if you need to explicitly name the standard input file
1315 in your command line.
1317 If the source is empty, @command{@value{AS}} produces a small, empty object
1322 @subheading Filenames and Line-numbers
1324 @cindex input file linenumbers
1325 @cindex line numbers, in input files
1326 There are two ways of locating a line in the input file (or files) and
1327 either may be used in reporting error messages. One way refers to a line
1328 number in a physical file; the other refers to a line number in a
1329 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1331 @dfn{Physical files} are those files named in the command line given
1332 to @command{@value{AS}}.
1334 @dfn{Logical files} are simply names declared explicitly by assembler
1335 directives; they bear no relation to physical files. Logical file names help
1336 error messages reflect the original source file, when @command{@value{AS}} source
1337 is itself synthesized from other files. @command{@value{AS}} understands the
1338 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1339 @ref{File,,@code{.file}}.
1342 @section Output (Object) File
1348 Every time you run @command{@value{AS}} it produces an output file, which is
1349 your assembly language program translated into numbers. This file
1350 is the object file. Its default name is
1358 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1360 You can give it another name by using the @option{-o} option. Conventionally,
1361 object file names end with @file{.o}. The default name is used for historical
1362 reasons: older assemblers were capable of assembling self-contained programs
1363 directly into a runnable program. (For some formats, this isn't currently
1364 possible, but it can be done for the @code{a.out} format.)
1368 The object file is meant for input to the linker @code{@value{LD}}. It contains
1369 assembled program code, information to help @code{@value{LD}} integrate
1370 the assembled program into a runnable file, and (optionally) symbolic
1371 information for the debugger.
1373 @c link above to some info file(s) like the description of a.out.
1374 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1377 @section Error and Warning Messages
1379 @c man begin DESCRIPTION
1381 @cindex error messages
1382 @cindex warning messages
1383 @cindex messages from assembler
1384 @command{@value{AS}} may write warnings and error messages to the standard error
1385 file (usually your terminal). This should not happen when a compiler
1386 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1387 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1388 grave problem that stops the assembly.
1392 @cindex format of warning messages
1393 Warning messages have the format
1396 file_name:@b{NNN}:Warning Message Text
1400 @cindex line numbers, in warnings/errors
1401 (where @b{NNN} is a line number). If a logical file name has been given
1402 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1403 the current input file is used. If a logical line number was given
1405 (@pxref{Line,,@code{.line}})
1409 (@pxref{Line,,@code{.line}})
1412 (@pxref{Ln,,@code{.ln}})
1415 then it is used to calculate the number printed,
1416 otherwise the actual line in the current source file is printed. The
1417 message text is intended to be self explanatory (in the grand Unix
1420 @cindex format of error messages
1421 Error messages have the format
1423 file_name:@b{NNN}:FATAL:Error Message Text
1425 The file name and line number are derived as for warning
1426 messages. The actual message text may be rather less explanatory
1427 because many of them aren't supposed to happen.
1430 @chapter Command-Line Options
1432 @cindex options, all versions of assembler
1433 This chapter describes command-line options available in @emph{all}
1434 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1436 to the @value{TARGET} target.
1439 to particular machine architectures.
1442 @c man begin DESCRIPTION
1444 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
1445 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1446 The assembler arguments must be separated from each other (and the @samp{-Wa})
1447 by commas. For example:
1450 gcc -c -g -O -Wa,-alh,-L file.c
1454 This passes two options to the assembler: @samp{-alh} (emit a listing to
1455 standard output with high-level and assembly source) and @samp{-L} (retain
1456 local symbols in the symbol table).
1458 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1459 command-line options are automatically passed to the assembler by the compiler.
1460 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1461 precisely what options it passes to each compilation pass, including the
1467 * a:: -a[cdhlns] enable listings
1468 * alternate:: --alternate enable alternate macro syntax
1469 * D:: -D for compatibility
1470 * f:: -f to work faster
1471 * I:: -I for .include search path
1472 @ifclear DIFF-TBL-KLUGE
1473 * K:: -K for compatibility
1475 @ifset DIFF-TBL-KLUGE
1476 * K:: -K for difference tables
1479 * L:: -L to retain local labels
1480 * listing:: --listing-XXX to configure listing output
1481 * M:: -M or --mri to assemble in MRI compatibility mode
1482 * MD:: --MD for dependency tracking
1483 * o:: -o to name the object file
1484 * R:: -R to join data and text sections
1485 * statistics:: --statistics to see statistics about assembly
1486 * traditional-format:: --traditional-format for compatible output
1487 * v:: -v to announce version
1488 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1489 * Z:: -Z to make object file even after errors
1493 @section Enable Listings: @option{-a[cdhlns]}
1502 @cindex listings, enabling
1503 @cindex assembly listings, enabling
1505 These options enable listing output from the assembler. By itself,
1506 @samp{-a} requests high-level, assembly, and symbols listing.
1507 You can use other letters to select specific options for the list:
1508 @samp{-ah} requests a high-level language listing,
1509 @samp{-al} requests an output-program assembly listing, and
1510 @samp{-as} requests a symbol table listing.
1511 High-level listings require that a compiler debugging option like
1512 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1515 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1516 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1517 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1518 omitted from the listing.
1520 Use the @samp{-ad} option to omit debugging directives from the
1523 Once you have specified one of these options, you can further control
1524 listing output and its appearance using the directives @code{.list},
1525 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1527 The @samp{-an} option turns off all forms processing.
1528 If you do not request listing output with one of the @samp{-a} options, the
1529 listing-control directives have no effect.
1531 The letters after @samp{-a} may be combined into one option,
1532 @emph{e.g.}, @samp{-aln}.
1534 Note if the assembler source is coming from the standard input (eg because it
1535 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1536 is being used) then the listing will not contain any comments or preprocessor
1537 directives. This is because the listing code buffers input source lines from
1538 stdin only after they have been preprocessed by the assembler. This reduces
1539 memory usage and makes the code more efficient.
1542 @section @option{--alternate}
1545 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
1548 @section @option{-D}
1551 This option has no effect whatsoever, but it is accepted to make it more
1552 likely that scripts written for other assemblers also work with
1553 @command{@value{AS}}.
1556 @section Work Faster: @option{-f}
1559 @cindex trusted compiler
1560 @cindex faster processing (@option{-f})
1561 @samp{-f} should only be used when assembling programs written by a
1562 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1563 and comment preprocessing on
1564 the input file(s) before assembling them. @xref{Preprocessing,
1568 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1569 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1574 @section @code{.include} Search Path: @option{-I} @var{path}
1576 @kindex -I @var{path}
1577 @cindex paths for @code{.include}
1578 @cindex search path for @code{.include}
1579 @cindex @code{include} directive search path
1580 Use this option to add a @var{path} to the list of directories
1581 @command{@value{AS}} searches for files specified in @code{.include}
1582 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1583 many times as necessary to include a variety of paths. The current
1584 working directory is always searched first; after that, @command{@value{AS}}
1585 searches any @samp{-I} directories in the same order as they were
1586 specified (left to right) on the command line.
1589 @section Difference Tables: @option{-K}
1592 @ifclear DIFF-TBL-KLUGE
1593 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1594 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1595 where it can be used to warn when the assembler alters the machine code
1596 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1597 family does not have the addressing limitations that sometimes lead to this
1598 alteration on other platforms.
1601 @ifset DIFF-TBL-KLUGE
1602 @cindex difference tables, warning
1603 @cindex warning for altered difference tables
1604 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1605 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1606 You can use the @samp{-K} option if you want a warning issued when this
1611 @section Include Local Labels: @option{-L}
1614 @cindex local labels, retaining in output
1615 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1616 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1617 debugging, because they are intended for the use of programs (like
1618 compilers) that compose assembler programs, not for your notice.
1619 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1620 normally debug with them.
1622 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1623 in the object file. Usually if you do this you also tell the linker
1624 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1626 By default, a local label is any label beginning with @samp{L}, but each
1627 target is allowed to redefine the local label prefix.
1629 On the HPPA local labels begin with @samp{L$}.
1633 @section Configuring listing output: @option{--listing}
1635 The listing feature of the assembler can be enabled via the command line switch
1636 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1637 hex dump of the corresponding locations in the output object file, and displays
1638 them as a listing file. The format of this listing can be controlled by pseudo
1639 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1640 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1643 @item --listing-lhs-width=@samp{number}
1644 @kindex --listing-lhs-width
1645 @cindex Width of first line disassembly output
1646 Sets the maximum width, in words, of the first line of the hex byte dump. This
1647 dump appears on the left hand side of the listing output.
1649 @item --listing-lhs-width2=@samp{number}
1650 @kindex --listing-lhs-width2
1651 @cindex Width of continuation lines of disassembly output
1652 Sets the maximum width, in words, of any further lines of the hex byte dump for
1653 a given input source line. If this value is not specified, it defaults to being
1654 the same as the value specified for @samp{--listing-lhs-width}. If neither
1655 switch is used the default is to one.
1657 @item --listing-rhs-width=@samp{number}
1658 @kindex --listing-rhs-width
1659 @cindex Width of source line output
1660 Sets the maximum width, in characters, of the source line that is displayed
1661 alongside the hex dump. The default value for this parameter is 100. The
1662 source line is displayed on the right hand side of the listing output.
1664 @item --listing-cont-lines=@samp{number}
1665 @kindex --listing-cont-lines
1666 @cindex Maximum number of continuation lines
1667 Sets the maximum number of continuation lines of hex dump that will be
1668 displayed for a given single line of source input. The default value is 4.
1672 @section Assemble in MRI Compatibility Mode: @option{-M}
1675 @cindex MRI compatibility mode
1676 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1677 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1678 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1679 configured target) assembler from Microtec Research. The exact nature of the
1680 MRI syntax will not be documented here; see the MRI manuals for more
1681 information. Note in particular that the handling of macros and macro
1682 arguments is somewhat different. The purpose of this option is to permit
1683 assembling existing MRI assembler code using @command{@value{AS}}.
1685 The MRI compatibility is not complete. Certain operations of the MRI assembler
1686 depend upon its object file format, and can not be supported using other object
1687 file formats. Supporting these would require enhancing each object file format
1688 individually. These are:
1691 @item global symbols in common section
1693 The m68k MRI assembler supports common sections which are merged by the linker.
1694 Other object file formats do not support this. @command{@value{AS}} handles
1695 common sections by treating them as a single common symbol. It permits local
1696 symbols to be defined within a common section, but it can not support global
1697 symbols, since it has no way to describe them.
1699 @item complex relocations
1701 The MRI assemblers support relocations against a negated section address, and
1702 relocations which combine the start addresses of two or more sections. These
1703 are not support by other object file formats.
1705 @item @code{END} pseudo-op specifying start address
1707 The MRI @code{END} pseudo-op permits the specification of a start address.
1708 This is not supported by other object file formats. The start address may
1709 instead be specified using the @option{-e} option to the linker, or in a linker
1712 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1714 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1715 name to the output file. This is not supported by other object file formats.
1717 @item @code{ORG} pseudo-op
1719 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1720 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1721 which changes the location within the current section. Absolute sections are
1722 not supported by other object file formats. The address of a section may be
1723 assigned within a linker script.
1726 There are some other features of the MRI assembler which are not supported by
1727 @command{@value{AS}}, typically either because they are difficult or because they
1728 seem of little consequence. Some of these may be supported in future releases.
1732 @item EBCDIC strings
1734 EBCDIC strings are not supported.
1736 @item packed binary coded decimal
1738 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1739 and @code{DCB.P} pseudo-ops are not supported.
1741 @item @code{FEQU} pseudo-op
1743 The m68k @code{FEQU} pseudo-op is not supported.
1745 @item @code{NOOBJ} pseudo-op
1747 The m68k @code{NOOBJ} pseudo-op is not supported.
1749 @item @code{OPT} branch control options
1751 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1752 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1753 relaxes all branches, whether forward or backward, to an appropriate size, so
1754 these options serve no purpose.
1756 @item @code{OPT} list control options
1758 The following m68k @code{OPT} list control options are ignored: @code{C},
1759 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1760 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1762 @item other @code{OPT} options
1764 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1765 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1767 @item @code{OPT} @code{D} option is default
1769 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1770 @code{OPT NOD} may be used to turn it off.
1772 @item @code{XREF} pseudo-op.
1774 The m68k @code{XREF} pseudo-op is ignored.
1776 @item @code{.debug} pseudo-op
1778 The i960 @code{.debug} pseudo-op is not supported.
1780 @item @code{.extended} pseudo-op
1782 The i960 @code{.extended} pseudo-op is not supported.
1784 @item @code{.list} pseudo-op.
1786 The various options of the i960 @code{.list} pseudo-op are not supported.
1788 @item @code{.optimize} pseudo-op
1790 The i960 @code{.optimize} pseudo-op is not supported.
1792 @item @code{.output} pseudo-op
1794 The i960 @code{.output} pseudo-op is not supported.
1796 @item @code{.setreal} pseudo-op
1798 The i960 @code{.setreal} pseudo-op is not supported.
1803 @section Dependency Tracking: @option{--MD}
1806 @cindex dependency tracking
1809 @command{@value{AS}} can generate a dependency file for the file it creates. This
1810 file consists of a single rule suitable for @code{make} describing the
1811 dependencies of the main source file.
1813 The rule is written to the file named in its argument.
1815 This feature is used in the automatic updating of makefiles.
1818 @section Name the Object File: @option{-o}
1821 @cindex naming object file
1822 @cindex object file name
1823 There is always one object file output when you run @command{@value{AS}}. By
1824 default it has the name
1827 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1841 You use this option (which takes exactly one filename) to give the
1842 object file a different name.
1844 Whatever the object file is called, @command{@value{AS}} overwrites any
1845 existing file of the same name.
1848 @section Join Data and Text Sections: @option{-R}
1851 @cindex data and text sections, joining
1852 @cindex text and data sections, joining
1853 @cindex joining text and data sections
1854 @cindex merging text and data sections
1855 @option{-R} tells @command{@value{AS}} to write the object file as if all
1856 data-section data lives in the text section. This is only done at
1857 the very last moment: your binary data are the same, but data
1858 section parts are relocated differently. The data section part of
1859 your object file is zero bytes long because all its bytes are
1860 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1862 When you specify @option{-R} it would be possible to generate shorter
1863 address displacements (because we do not have to cross between text and
1864 data section). We refrain from doing this simply for compatibility with
1865 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1868 When @command{@value{AS}} is configured for COFF or ELF output,
1869 this option is only useful if you use sections named @samp{.text} and
1874 @option{-R} is not supported for any of the HPPA targets. Using
1875 @option{-R} generates a warning from @command{@value{AS}}.
1879 @section Display Assembly Statistics: @option{--statistics}
1881 @kindex --statistics
1882 @cindex statistics, about assembly
1883 @cindex time, total for assembly
1884 @cindex space used, maximum for assembly
1885 Use @samp{--statistics} to display two statistics about the resources used by
1886 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1887 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1890 @node traditional-format
1891 @section Compatible Output: @option{--traditional-format}
1893 @kindex --traditional-format
1894 For some targets, the output of @command{@value{AS}} is different in some ways
1895 from the output of some existing assembler. This switch requests
1896 @command{@value{AS}} to use the traditional format instead.
1898 For example, it disables the exception frame optimizations which
1899 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1902 @section Announce Version: @option{-v}
1906 @cindex assembler version
1907 @cindex version of assembler
1908 You can find out what version of as is running by including the
1909 option @samp{-v} (which you can also spell as @samp{-version}) on the
1913 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1915 @command{@value{AS}} should never give a warning or error message when
1916 assembling compiler output. But programs written by people often
1917 cause @command{@value{AS}} to give a warning that a particular assumption was
1918 made. All such warnings are directed to the standard error file.
1922 @cindex suppressing warnings
1923 @cindex warnings, suppressing
1924 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1925 This only affects the warning messages: it does not change any particular of
1926 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1929 @kindex --fatal-warnings
1930 @cindex errors, caused by warnings
1931 @cindex warnings, causing error
1932 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1933 files that generate warnings to be in error.
1936 @cindex warnings, switching on
1937 You can switch these options off again by specifying @option{--warn}, which
1938 causes warnings to be output as usual.
1941 @section Generate Object File in Spite of Errors: @option{-Z}
1942 @cindex object file, after errors
1943 @cindex errors, continuing after
1944 After an error message, @command{@value{AS}} normally produces no output. If for
1945 some reason you are interested in object file output even after
1946 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1947 option. If there are any errors, @command{@value{AS}} continues anyways, and
1948 writes an object file after a final warning message of the form @samp{@var{n}
1949 errors, @var{m} warnings, generating bad object file.}
1954 @cindex machine-independent syntax
1955 @cindex syntax, machine-independent
1956 This chapter describes the machine-independent syntax allowed in a
1957 source file. @command{@value{AS}} syntax is similar to what many other
1958 assemblers use; it is inspired by the BSD 4.2
1963 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1967 * Preprocessing:: Preprocessing
1968 * Whitespace:: Whitespace
1969 * Comments:: Comments
1970 * Symbol Intro:: Symbols
1971 * Statements:: Statements
1972 * Constants:: Constants
1976 @section Preprocessing
1978 @cindex preprocessing
1979 The @command{@value{AS}} internal preprocessor:
1981 @cindex whitespace, removed by preprocessor
1983 adjusts and removes extra whitespace. It leaves one space or tab before
1984 the keywords on a line, and turns any other whitespace on the line into
1987 @cindex comments, removed by preprocessor
1989 removes all comments, replacing them with a single space, or an
1990 appropriate number of newlines.
1992 @cindex constants, converted by preprocessor
1994 converts character constants into the appropriate numeric values.
1997 It does not do macro processing, include file handling, or
1998 anything else you may get from your C compiler's preprocessor. You can
1999 do include file processing with the @code{.include} directive
2000 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2001 to get other ``CPP'' style preprocessing by giving the input file a
2002 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
2003 Output, gcc.info, Using GNU CC}.
2005 Excess whitespace, comments, and character constants
2006 cannot be used in the portions of the input text that are not
2009 @cindex turning preprocessing on and off
2010 @cindex preprocessing, turning on and off
2013 If the first line of an input file is @code{#NO_APP} or if you use the
2014 @samp{-f} option, whitespace and comments are not removed from the input file.
2015 Within an input file, you can ask for whitespace and comment removal in
2016 specific portions of the by putting a line that says @code{#APP} before the
2017 text that may contain whitespace or comments, and putting a line that says
2018 @code{#NO_APP} after this text. This feature is mainly intend to support
2019 @code{asm} statements in compilers whose output is otherwise free of comments
2026 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2027 Whitespace is used to separate symbols, and to make programs neater for
2028 people to read. Unless within character constants
2029 (@pxref{Characters,,Character Constants}), any whitespace means the same
2030 as exactly one space.
2036 There are two ways of rendering comments to @command{@value{AS}}. In both
2037 cases the comment is equivalent to one space.
2039 Anything from @samp{/*} through the next @samp{*/} is a comment.
2040 This means you may not nest these comments.
2044 The only way to include a newline ('\n') in a comment
2045 is to use this sort of comment.
2048 /* This sort of comment does not nest. */
2051 @cindex line comment character
2052 Anything from the @dfn{line comment} character to the next newline
2053 is considered a comment and is ignored. The line comment character is
2055 @samp{;} for the AMD 29K family;
2058 @samp{;} on the ARC;
2061 @samp{@@} on the ARM;
2064 @samp{;} for the H8/300 family;
2067 @samp{!} for the H8/500 family;
2070 @samp{;} for the HPPA;
2073 @samp{#} on the i386 and x86-64;
2076 @samp{#} on the i960;
2079 @samp{;} for the PDP-11;
2082 @samp{;} for picoJava;
2085 @samp{#} for Motorola PowerPC;
2088 @samp{!} for the Renesas / SuperH SH;
2091 @samp{!} on the SPARC;
2094 @samp{#} on the ip2k;
2097 @samp{#} on the m32r;
2100 @samp{|} on the 680x0;
2103 @samp{#} on the 68HC11 and 68HC12;
2106 @samp{;} on the M880x0;
2109 @samp{#} on the Vax;
2112 @samp{!} for the Z8000;
2115 @samp{#} on the V850;
2118 @samp{#} for Xtensa systems;
2120 see @ref{Machine Dependencies}. @refill
2121 @c FIXME What about i860?
2124 On some machines there are two different line comment characters. One
2125 character only begins a comment if it is the first non-whitespace character on
2126 a line, while the other always begins a comment.
2130 The V850 assembler also supports a double dash as starting a comment that
2131 extends to the end of the line.
2137 @cindex lines starting with @code{#}
2138 @cindex logical line numbers
2139 To be compatible with past assemblers, lines that begin with @samp{#} have a
2140 special interpretation. Following the @samp{#} should be an absolute
2141 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2142 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
2143 new logical file name. The rest of the line, if any, should be whitespace.
2145 If the first non-whitespace characters on the line are not numeric,
2146 the line is ignored. (Just like a comment.)
2149 # This is an ordinary comment.
2150 # 42-6 "new_file_name" # New logical file name
2151 # This is logical line # 36.
2153 This feature is deprecated, and may disappear from future versions
2154 of @command{@value{AS}}.
2159 @cindex characters used in symbols
2160 @ifclear SPECIAL-SYMS
2161 A @dfn{symbol} is one or more characters chosen from the set of all
2162 letters (both upper and lower case), digits and the three characters
2168 A @dfn{symbol} is one or more characters chosen from the set of all
2169 letters (both upper and lower case), digits and the three characters
2170 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2176 On most machines, you can also use @code{$} in symbol names; exceptions
2177 are noted in @ref{Machine Dependencies}.
2179 No symbol may begin with a digit. Case is significant.
2180 There is no length limit: all characters are significant. Symbols are
2181 delimited by characters not in that set, or by the beginning of a file
2182 (since the source program must end with a newline, the end of a file is
2183 not a possible symbol delimiter). @xref{Symbols}.
2184 @cindex length of symbols
2189 @cindex statements, structure of
2190 @cindex line separator character
2191 @cindex statement separator character
2193 @ifclear abnormal-separator
2194 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2195 semicolon (@samp{;}). The newline or semicolon is considered part of
2196 the preceding statement. Newlines and semicolons within character
2197 constants are an exception: they do not end statements.
2199 @ifset abnormal-separator
2201 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2202 sign (@samp{@@}). The newline or at sign is considered part of the
2203 preceding statement. Newlines and at signs within character constants
2204 are an exception: they do not end statements.
2207 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2208 point (@samp{!}). The newline or exclamation point is considered part of the
2209 preceding statement. Newlines and exclamation points within character
2210 constants are an exception: they do not end statements.
2213 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2214 H8/300) a dollar sign (@samp{$}); or (for the
2217 (@samp{;}). The newline or separator character is considered part of
2218 the preceding statement. Newlines and separators within character
2219 constants are an exception: they do not end statements.
2224 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2225 separator character. (The line separator is usually @samp{;}, unless
2226 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2227 newline or separator character is considered part of the preceding
2228 statement. Newlines and separators within character constants are an
2229 exception: they do not end statements.
2232 @cindex newline, required at file end
2233 @cindex EOF, newline must precede
2234 It is an error to end any statement with end-of-file: the last
2235 character of any input file should be a newline.@refill
2237 An empty statement is allowed, and may include whitespace. It is ignored.
2239 @cindex instructions and directives
2240 @cindex directives and instructions
2241 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2242 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2244 A statement begins with zero or more labels, optionally followed by a
2245 key symbol which determines what kind of statement it is. The key
2246 symbol determines the syntax of the rest of the statement. If the
2247 symbol begins with a dot @samp{.} then the statement is an assembler
2248 directive: typically valid for any computer. If the symbol begins with
2249 a letter the statement is an assembly language @dfn{instruction}: it
2250 assembles into a machine language instruction.
2252 Different versions of @command{@value{AS}} for different computers
2253 recognize different instructions. In fact, the same symbol may
2254 represent a different instruction in a different computer's assembly
2258 @cindex @code{:} (label)
2259 @cindex label (@code{:})
2260 A label is a symbol immediately followed by a colon (@code{:}).
2261 Whitespace before a label or after a colon is permitted, but you may not
2262 have whitespace between a label's symbol and its colon. @xref{Labels}.
2265 For HPPA targets, labels need not be immediately followed by a colon, but
2266 the definition of a label must begin in column zero. This also implies that
2267 only one label may be defined on each line.
2271 label: .directive followed by something
2272 another_label: # This is an empty statement.
2273 instruction operand_1, operand_2, @dots{}
2280 A constant is a number, written so that its value is known by
2281 inspection, without knowing any context. Like this:
2284 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2285 .ascii "Ring the bell\7" # A string constant.
2286 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2287 .float 0f-314159265358979323846264338327\
2288 95028841971.693993751E-40 # - pi, a flonum.
2293 * Characters:: Character Constants
2294 * Numbers:: Number Constants
2298 @subsection Character Constants
2300 @cindex character constants
2301 @cindex constants, character
2302 There are two kinds of character constants. A @dfn{character} stands
2303 for one character in one byte and its value may be used in
2304 numeric expressions. String constants (properly called string
2305 @emph{literals}) are potentially many bytes and their values may not be
2306 used in arithmetic expressions.
2310 * Chars:: Characters
2314 @subsubsection Strings
2316 @cindex string constants
2317 @cindex constants, string
2318 A @dfn{string} is written between double-quotes. It may contain
2319 double-quotes or null characters. The way to get special characters
2320 into a string is to @dfn{escape} these characters: precede them with
2321 a backslash @samp{\} character. For example @samp{\\} represents
2322 one backslash: the first @code{\} is an escape which tells
2323 @command{@value{AS}} to interpret the second character literally as a backslash
2324 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2325 escape character). The complete list of escapes follows.
2327 @cindex escape codes, character
2328 @cindex character escape codes
2331 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2333 @cindex @code{\b} (backspace character)
2334 @cindex backspace (@code{\b})
2336 Mnemonic for backspace; for ASCII this is octal code 010.
2339 @c Mnemonic for EOText; for ASCII this is octal code 004.
2341 @cindex @code{\f} (formfeed character)
2342 @cindex formfeed (@code{\f})
2344 Mnemonic for FormFeed; for ASCII this is octal code 014.
2346 @cindex @code{\n} (newline character)
2347 @cindex newline (@code{\n})
2349 Mnemonic for newline; for ASCII this is octal code 012.
2352 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2354 @cindex @code{\r} (carriage return character)
2355 @cindex carriage return (@code{\r})
2357 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2360 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2361 @c other assemblers.
2363 @cindex @code{\t} (tab)
2364 @cindex tab (@code{\t})
2366 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2369 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2370 @c @item \x @var{digit} @var{digit} @var{digit}
2371 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2373 @cindex @code{\@var{ddd}} (octal character code)
2374 @cindex octal character code (@code{\@var{ddd}})
2375 @item \ @var{digit} @var{digit} @var{digit}
2376 An octal character code. The numeric code is 3 octal digits.
2377 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2378 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2380 @cindex @code{\@var{xd...}} (hex character code)
2381 @cindex hex character code (@code{\@var{xd...}})
2382 @item \@code{x} @var{hex-digits...}
2383 A hex character code. All trailing hex digits are combined. Either upper or
2384 lower case @code{x} works.
2386 @cindex @code{\\} (@samp{\} character)
2387 @cindex backslash (@code{\\})
2389 Represents one @samp{\} character.
2392 @c Represents one @samp{'} (accent acute) character.
2393 @c This is needed in single character literals
2394 @c (@xref{Characters,,Character Constants}.) to represent
2397 @cindex @code{\"} (doublequote character)
2398 @cindex doublequote (@code{\"})
2400 Represents one @samp{"} character. Needed in strings to represent
2401 this character, because an unescaped @samp{"} would end the string.
2403 @item \ @var{anything-else}
2404 Any other character when escaped by @kbd{\} gives a warning, but
2405 assembles as if the @samp{\} was not present. The idea is that if
2406 you used an escape sequence you clearly didn't want the literal
2407 interpretation of the following character. However @command{@value{AS}} has no
2408 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2409 code and warns you of the fact.
2412 Which characters are escapable, and what those escapes represent,
2413 varies widely among assemblers. The current set is what we think
2414 the BSD 4.2 assembler recognizes, and is a subset of what most C
2415 compilers recognize. If you are in doubt, do not use an escape
2419 @subsubsection Characters
2421 @cindex single character constant
2422 @cindex character, single
2423 @cindex constant, single character
2424 A single character may be written as a single quote immediately
2425 followed by that character. The same escapes apply to characters as
2426 to strings. So if you want to write the character backslash, you
2427 must write @kbd{'\\} where the first @code{\} escapes the second
2428 @code{\}. As you can see, the quote is an acute accent, not a
2429 grave accent. A newline
2431 @ifclear abnormal-separator
2432 (or semicolon @samp{;})
2434 @ifset abnormal-separator
2436 (or at sign @samp{@@})
2439 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2440 Renesas SH or H8/500)
2444 immediately following an acute accent is taken as a literal character
2445 and does not count as the end of a statement. The value of a character
2446 constant in a numeric expression is the machine's byte-wide code for
2447 that character. @command{@value{AS}} assumes your character code is ASCII:
2448 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2451 @subsection Number Constants
2453 @cindex constants, number
2454 @cindex number constants
2455 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2456 are stored in the target machine. @emph{Integers} are numbers that
2457 would fit into an @code{int} in the C language. @emph{Bignums} are
2458 integers, but they are stored in more than 32 bits. @emph{Flonums}
2459 are floating point numbers, described below.
2462 * Integers:: Integers
2467 * Bit Fields:: Bit Fields
2473 @subsubsection Integers
2475 @cindex constants, integer
2477 @cindex binary integers
2478 @cindex integers, binary
2479 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2480 the binary digits @samp{01}.
2482 @cindex octal integers
2483 @cindex integers, octal
2484 An octal integer is @samp{0} followed by zero or more of the octal
2485 digits (@samp{01234567}).
2487 @cindex decimal integers
2488 @cindex integers, decimal
2489 A decimal integer starts with a non-zero digit followed by zero or
2490 more digits (@samp{0123456789}).
2492 @cindex hexadecimal integers
2493 @cindex integers, hexadecimal
2494 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2495 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2497 Integers have the usual values. To denote a negative integer, use
2498 the prefix operator @samp{-} discussed under expressions
2499 (@pxref{Prefix Ops,,Prefix Operators}).
2502 @subsubsection Bignums
2505 @cindex constants, bignum
2506 A @dfn{bignum} has the same syntax and semantics as an integer
2507 except that the number (or its negative) takes more than 32 bits to
2508 represent in binary. The distinction is made because in some places
2509 integers are permitted while bignums are not.
2512 @subsubsection Flonums
2514 @cindex floating point numbers
2515 @cindex constants, floating point
2517 @cindex precision, floating point
2518 A @dfn{flonum} represents a floating point number. The translation is
2519 indirect: a decimal floating point number from the text is converted by
2520 @command{@value{AS}} to a generic binary floating point number of more than
2521 sufficient precision. This generic floating point number is converted
2522 to a particular computer's floating point format (or formats) by a
2523 portion of @command{@value{AS}} specialized to that computer.
2525 A flonum is written by writing (in order)
2530 (@samp{0} is optional on the HPPA.)
2534 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2536 @kbd{e} is recommended. Case is not important.
2538 @c FIXME: verify if flonum syntax really this vague for most cases
2539 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2540 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2543 On the H8/300, H8/500,
2544 Renesas / SuperH SH,
2545 and AMD 29K architectures, the letter must be
2546 one of the letters @samp{DFPRSX} (in upper or lower case).
2548 On the ARC, the letter must be one of the letters @samp{DFRS}
2549 (in upper or lower case).
2551 On the Intel 960 architecture, the letter must be
2552 one of the letters @samp{DFT} (in upper or lower case).
2554 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2558 One of the letters @samp{DFPRSX} (in upper or lower case).
2561 One of the letters @samp{DFRS} (in upper or lower case).
2564 One of the letters @samp{DFPRSX} (in upper or lower case).
2567 The letter @samp{E} (upper case only).
2570 One of the letters @samp{DFT} (in upper or lower case).
2575 An optional sign: either @samp{+} or @samp{-}.
2578 An optional @dfn{integer part}: zero or more decimal digits.
2581 An optional @dfn{fractional part}: @samp{.} followed by zero
2582 or more decimal digits.
2585 An optional exponent, consisting of:
2589 An @samp{E} or @samp{e}.
2590 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2591 @c principle this can perfectly well be different on different targets.
2593 Optional sign: either @samp{+} or @samp{-}.
2595 One or more decimal digits.
2600 At least one of the integer part or the fractional part must be
2601 present. The floating point number has the usual base-10 value.
2603 @command{@value{AS}} does all processing using integers. Flonums are computed
2604 independently of any floating point hardware in the computer running
2605 @command{@value{AS}}.
2609 @c Bit fields are written as a general facility but are also controlled
2610 @c by a conditional-compilation flag---which is as of now (21mar91)
2611 @c turned on only by the i960 config of GAS.
2613 @subsubsection Bit Fields
2616 @cindex constants, bit field
2617 You can also define numeric constants as @dfn{bit fields}.
2618 specify two numbers separated by a colon---
2620 @var{mask}:@var{value}
2623 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2626 The resulting number is then packed
2628 @c this conditional paren in case bit fields turned on elsewhere than 960
2629 (in host-dependent byte order)
2631 into a field whose width depends on which assembler directive has the
2632 bit-field as its argument. Overflow (a result from the bitwise and
2633 requiring more binary digits to represent) is not an error; instead,
2634 more constants are generated, of the specified width, beginning with the
2635 least significant digits.@refill
2637 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2638 @code{.short}, and @code{.word} accept bit-field arguments.
2643 @chapter Sections and Relocation
2648 * Secs Background:: Background
2649 * Ld Sections:: Linker Sections
2650 * As Sections:: Assembler Internal Sections
2651 * Sub-Sections:: Sub-Sections
2655 @node Secs Background
2658 Roughly, a section is a range of addresses, with no gaps; all data
2659 ``in'' those addresses is treated the same for some particular purpose.
2660 For example there may be a ``read only'' section.
2662 @cindex linker, and assembler
2663 @cindex assembler, and linker
2664 The linker @code{@value{LD}} reads many object files (partial programs) and
2665 combines their contents to form a runnable program. When @command{@value{AS}}
2666 emits an object file, the partial program is assumed to start at address 0.
2667 @code{@value{LD}} assigns the final addresses for the partial program, so that
2668 different partial programs do not overlap. This is actually an
2669 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2672 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2673 addresses. These blocks slide to their run-time addresses as rigid
2674 units; their length does not change and neither does the order of bytes
2675 within them. Such a rigid unit is called a @emph{section}. Assigning
2676 run-time addresses to sections is called @dfn{relocation}. It includes
2677 the task of adjusting mentions of object-file addresses so they refer to
2678 the proper run-time addresses.
2680 For the H8/300 and H8/500,
2681 and for the Renesas / SuperH SH,
2682 @command{@value{AS}} pads sections if needed to
2683 ensure they end on a word (sixteen bit) boundary.
2686 @cindex standard assembler sections
2687 An object file written by @command{@value{AS}} has at least three sections, any
2688 of which may be empty. These are named @dfn{text}, @dfn{data} and
2693 When it generates COFF or ELF output,
2695 @command{@value{AS}} can also generate whatever other named sections you specify
2696 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2697 If you do not use any directives that place output in the @samp{.text}
2698 or @samp{.data} sections, these sections still exist, but are empty.
2703 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2705 @command{@value{AS}} can also generate whatever other named sections you
2706 specify using the @samp{.space} and @samp{.subspace} directives. See
2707 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2708 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2709 assembler directives.
2712 Additionally, @command{@value{AS}} uses different names for the standard
2713 text, data, and bss sections when generating SOM output. Program text
2714 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2715 BSS into @samp{$BSS$}.
2719 Within the object file, the text section starts at address @code{0}, the
2720 data section follows, and the bss section follows the data section.
2723 When generating either SOM or ELF output files on the HPPA, the text
2724 section starts at address @code{0}, the data section at address
2725 @code{0x4000000}, and the bss section follows the data section.
2728 To let @code{@value{LD}} know which data changes when the sections are
2729 relocated, and how to change that data, @command{@value{AS}} also writes to the
2730 object file details of the relocation needed. To perform relocation
2731 @code{@value{LD}} must know, each time an address in the object
2735 Where in the object file is the beginning of this reference to
2738 How long (in bytes) is this reference?
2740 Which section does the address refer to? What is the numeric value of
2742 (@var{address}) @minus{} (@var{start-address of section})?
2745 Is the reference to an address ``Program-Counter relative''?
2748 @cindex addresses, format of
2749 @cindex section-relative addressing
2750 In fact, every address @command{@value{AS}} ever uses is expressed as
2752 (@var{section}) + (@var{offset into section})
2755 Further, most expressions @command{@value{AS}} computes have this section-relative
2758 (For some object formats, such as SOM for the HPPA, some expressions are
2759 symbol-relative instead.)
2762 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2763 @var{N} into section @var{secname}.''
2765 Apart from text, data and bss sections you need to know about the
2766 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2767 addresses in the absolute section remain unchanged. For example, address
2768 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2769 @code{@value{LD}}. Although the linker never arranges two partial programs'
2770 data sections with overlapping addresses after linking, @emph{by definition}
2771 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2772 part of a program is always the same address when the program is running as
2773 address @code{@{absolute@ 239@}} in any other part of the program.
2775 The idea of sections is extended to the @dfn{undefined} section. Any
2776 address whose section is unknown at assembly time is by definition
2777 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2778 Since numbers are always defined, the only way to generate an undefined
2779 address is to mention an undefined symbol. A reference to a named
2780 common block would be such a symbol: its value is unknown at assembly
2781 time so it has section @emph{undefined}.
2783 By analogy the word @emph{section} is used to describe groups of sections in
2784 the linked program. @code{@value{LD}} puts all partial programs' text
2785 sections in contiguous addresses in the linked program. It is
2786 customary to refer to the @emph{text section} of a program, meaning all
2787 the addresses of all partial programs' text sections. Likewise for
2788 data and bss sections.
2790 Some sections are manipulated by @code{@value{LD}}; others are invented for
2791 use of @command{@value{AS}} and have no meaning except during assembly.
2794 @section Linker Sections
2795 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2800 @cindex named sections
2801 @cindex sections, named
2802 @item named sections
2805 @cindex text section
2806 @cindex data section
2810 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2811 separate but equal sections. Anything you can say of one section is
2814 When the program is running, however, it is
2815 customary for the text section to be unalterable. The
2816 text section is often shared among processes: it contains
2817 instructions, constants and the like. The data section of a running
2818 program is usually alterable: for example, C variables would be stored
2819 in the data section.
2824 This section contains zeroed bytes when your program begins running. It
2825 is used to hold uninitialized variables or common storage. The length of
2826 each partial program's bss section is important, but because it starts
2827 out containing zeroed bytes there is no need to store explicit zero
2828 bytes in the object file. The bss section was invented to eliminate
2829 those explicit zeros from object files.
2831 @cindex absolute section
2832 @item absolute section
2833 Address 0 of this section is always ``relocated'' to runtime address 0.
2834 This is useful if you want to refer to an address that @code{@value{LD}} must
2835 not change when relocating. In this sense we speak of absolute
2836 addresses being ``unrelocatable'': they do not change during relocation.
2838 @cindex undefined section
2839 @item undefined section
2840 This ``section'' is a catch-all for address references to objects not in
2841 the preceding sections.
2842 @c FIXME: ref to some other doc on obj-file formats could go here.
2845 @cindex relocation example
2846 An idealized example of three relocatable sections follows.
2848 The example uses the traditional section names @samp{.text} and @samp{.data}.
2850 Memory addresses are on the horizontal axis.
2854 @c END TEXI2ROFF-KILL
2857 partial program # 1: |ttttt|dddd|00|
2864 partial program # 2: |TTT|DDD|000|
2867 +--+---+-----+--+----+---+-----+~~
2868 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2869 +--+---+-----+--+----+---+-----+~~
2871 addresses: 0 @dots{}
2878 \line{\it Partial program \#1: \hfil}
2879 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2880 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2882 \line{\it Partial program \#2: \hfil}
2883 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2884 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2886 \line{\it linked program: \hfil}
2887 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2888 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2889 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2890 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2892 \line{\it addresses: \hfil}
2896 @c END TEXI2ROFF-KILL
2899 @section Assembler Internal Sections
2901 @cindex internal assembler sections
2902 @cindex sections in messages, internal
2903 These sections are meant only for the internal use of @command{@value{AS}}. They
2904 have no meaning at run-time. You do not really need to know about these
2905 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2906 warning messages, so it might be helpful to have an idea of their
2907 meanings to @command{@value{AS}}. These sections are used to permit the
2908 value of every expression in your assembly language program to be a
2909 section-relative address.
2912 @cindex assembler internal logic error
2913 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2914 An internal assembler logic error has been found. This means there is a
2915 bug in the assembler.
2917 @cindex expr (internal section)
2919 The assembler stores complex expression internally as combinations of
2920 symbols. When it needs to represent an expression as a symbol, it puts
2921 it in the expr section.
2923 @c FIXME item transfer[t] vector preload
2924 @c FIXME item transfer[t] vector postload
2925 @c FIXME item register
2929 @section Sub-Sections
2931 @cindex numbered subsections
2932 @cindex grouping data
2938 fall into two sections: text and data.
2940 You may have separate groups of
2942 data in named sections
2946 data in named sections
2952 that you want to end up near to each other in the object file, even though they
2953 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2954 use @dfn{subsections} for this purpose. Within each section, there can be
2955 numbered subsections with values from 0 to 8192. Objects assembled into the
2956 same subsection go into the object file together with other objects in the same
2957 subsection. For example, a compiler might want to store constants in the text
2958 section, but might not want to have them interspersed with the program being
2959 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2960 section of code being output, and a @samp{.text 1} before each group of
2961 constants being output.
2963 Subsections are optional. If you do not use subsections, everything
2964 goes in subsection number zero.
2967 Each subsection is zero-padded up to a multiple of four bytes.
2968 (Subsections may be padded a different amount on different flavors
2969 of @command{@value{AS}}.)
2973 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2974 boundary (two bytes).
2975 The same is true on the Renesas SH.
2978 @c FIXME section padding (alignment)?
2979 @c Rich Pixley says padding here depends on target obj code format; that
2980 @c doesn't seem particularly useful to say without further elaboration,
2981 @c so for now I say nothing about it. If this is a generic BFD issue,
2982 @c these paragraphs might need to vanish from this manual, and be
2983 @c discussed in BFD chapter of binutils (or some such).
2986 On the AMD 29K family, no particular padding is added to section or
2987 subsection sizes; @value{AS} forces no alignment on this platform.
2991 Subsections appear in your object file in numeric order, lowest numbered
2992 to highest. (All this to be compatible with other people's assemblers.)
2993 The object file contains no representation of subsections; @code{@value{LD}} and
2994 other programs that manipulate object files see no trace of them.
2995 They just see all your text subsections as a text section, and all your
2996 data subsections as a data section.
2998 To specify which subsection you want subsequent statements assembled
2999 into, use a numeric argument to specify it, in a @samp{.text
3000 @var{expression}} or a @samp{.data @var{expression}} statement.
3003 When generating COFF output, you
3008 can also use an extra subsection
3009 argument with arbitrary named sections: @samp{.section @var{name},
3014 When generating ELF output, you
3019 can also use the @code{.subsection} directive (@pxref{SubSection})
3020 to specify a subsection: @samp{.subsection @var{expression}}.
3022 @var{Expression} should be an absolute expression.
3023 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
3024 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3025 begins in @code{text 0}. For instance:
3027 .text 0 # The default subsection is text 0 anyway.
3028 .ascii "This lives in the first text subsection. *"
3030 .ascii "But this lives in the second text subsection."
3032 .ascii "This lives in the data section,"
3033 .ascii "in the first data subsection."
3035 .ascii "This lives in the first text section,"
3036 .ascii "immediately following the asterisk (*)."
3039 Each section has a @dfn{location counter} incremented by one for every byte
3040 assembled into that section. Because subsections are merely a convenience
3041 restricted to @command{@value{AS}} there is no concept of a subsection location
3042 counter. There is no way to directly manipulate a location counter---but the
3043 @code{.align} directive changes it, and any label definition captures its
3044 current value. The location counter of the section where statements are being
3045 assembled is said to be the @dfn{active} location counter.
3048 @section bss Section
3051 @cindex common variable storage
3052 The bss section is used for local common variable storage.
3053 You may allocate address space in the bss section, but you may
3054 not dictate data to load into it before your program executes. When
3055 your program starts running, all the contents of the bss
3056 section are zeroed bytes.
3058 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3059 @ref{Lcomm,,@code{.lcomm}}.
3061 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3062 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
3065 When assembling for a target which supports multiple sections, such as ELF or
3066 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3067 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3068 section. Typically the section will only contain symbol definitions and
3069 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3076 Symbols are a central concept: the programmer uses symbols to name
3077 things, the linker uses symbols to link, and the debugger uses symbols
3081 @cindex debuggers, and symbol order
3082 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3083 the same order they were declared. This may break some debuggers.
3088 * Setting Symbols:: Giving Symbols Other Values
3089 * Symbol Names:: Symbol Names
3090 * Dot:: The Special Dot Symbol
3091 * Symbol Attributes:: Symbol Attributes
3098 A @dfn{label} is written as a symbol immediately followed by a colon
3099 @samp{:}. The symbol then represents the current value of the
3100 active location counter, and is, for example, a suitable instruction
3101 operand. You are warned if you use the same symbol to represent two
3102 different locations: the first definition overrides any other
3106 On the HPPA, the usual form for a label need not be immediately followed by a
3107 colon, but instead must start in column zero. Only one label may be defined on
3108 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3109 provides a special directive @code{.label} for defining labels more flexibly.
3112 @node Setting Symbols
3113 @section Giving Symbols Other Values
3115 @cindex assigning values to symbols
3116 @cindex symbol values, assigning
3117 A symbol can be given an arbitrary value by writing a symbol, followed
3118 by an equals sign @samp{=}, followed by an expression
3119 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3120 directive. @xref{Set,,@code{.set}}.
3123 @section Symbol Names
3125 @cindex symbol names
3126 @cindex names, symbol
3127 @ifclear SPECIAL-SYMS
3128 Symbol names begin with a letter or with one of @samp{._}. On most
3129 machines, you can also use @code{$} in symbol names; exceptions are
3130 noted in @ref{Machine Dependencies}. That character may be followed by any
3131 string of digits, letters, dollar signs (unless otherwise noted in
3132 @ref{Machine Dependencies}), and underscores.
3135 For the AMD 29K family, @samp{?} is also allowed in the
3136 body of a symbol name, though not at its beginning.
3141 Symbol names begin with a letter or with one of @samp{._}. On the
3142 Renesas SH or the H8/500, you can also use @code{$} in symbol names. That
3143 character may be followed by any string of digits, letters, dollar signs (save
3144 on the H8/300), and underscores.
3148 Case of letters is significant: @code{foo} is a different symbol name
3151 Each symbol has exactly one name. Each name in an assembly language program
3152 refers to exactly one symbol. You may use that symbol name any number of times
3155 @subheading Local Symbol Names
3157 @cindex local symbol names
3158 @cindex symbol names, local
3159 @cindex temporary symbol names
3160 @cindex symbol names, temporary
3161 Local symbols help compilers and programmers use names temporarily.
3162 They create symbols which are guaranteed to be unique over the entire scope of
3163 the input source code and which can be referred to by a simple notation.
3164 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3165 represents any positive integer). To refer to the most recent previous
3166 definition of that symbol write @samp{@b{N}b}, using the same number as when
3167 you defined the label. To refer to the next definition of a local label, write
3168 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3171 There is no restriction on how you can use these labels, and you can reuse them
3172 too. So that it is possible to repeatedly define the same local label (using
3173 the same number @samp{@b{N}}), although you can only refer to the most recently
3174 defined local label of that number (for a backwards reference) or the next
3175 definition of a specific local label for a forward reference. It is also worth
3176 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3177 implemented in a slightly more efficient manner than the others.
3188 Which is the equivalent of:
3191 label_1: branch label_3
3192 label_2: branch label_1
3193 label_3: branch label_4
3194 label_4: branch label_3
3197 Local symbol names are only a notational device. They are immediately
3198 transformed into more conventional symbol names before the assembler uses them.
3199 The symbol names stored in the symbol table, appearing in error messages and
3200 optionally emitted to the object file. The names are constructed using these
3205 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3206 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3207 used for symbols you are never intended to see. If you use the
3208 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3209 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3210 you may use them in debugging.
3213 This is the number that was used in the local label definition. So if the
3214 label is written @samp{55:} then the number is @samp{55}.
3217 This unusual character is included so you do not accidentally invent a symbol
3218 of the same name. The character has ASCII value of @samp{\002} (control-B).
3220 @item @emph{ordinal number}
3221 This is a serial number to keep the labels distinct. The first definition of
3222 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3223 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3224 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3227 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3228 @code{3:} is named @code{L3@kbd{C-B}44}.
3230 @subheading Dollar Local Labels
3231 @cindex dollar local symbols
3233 @code{@value{AS}} also supports an even more local form of local labels called
3234 dollar labels. These labels go out of scope (ie they become undefined) as soon
3235 as a non-local label is defined. Thus they remain valid for only a small
3236 region of the input source code. Normal local labels, by contrast, remain in
3237 scope for the entire file, or until they are redefined by another occurrence of
3238 the same local label.
3240 Dollar labels are defined in exactly the same way as ordinary local labels,
3241 except that instead of being terminated by a colon, they are terminated by a
3242 dollar sign. eg @samp{@b{55$}}.
3244 They can also be distinguished from ordinary local labels by their transformed
3245 name which uses ASCII character @samp{\001} (control-A) as the magic character
3246 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3247 is named @samp{L6@kbd{C-A}5}.
3250 @section The Special Dot Symbol
3252 @cindex dot (symbol)
3253 @cindex @code{.} (symbol)
3254 @cindex current address
3255 @cindex location counter
3256 The special symbol @samp{.} refers to the current address that
3257 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3258 .long .} defines @code{melvin} to contain its own address.
3259 Assigning a value to @code{.} is treated the same as a @code{.org}
3260 directive. Thus, the expression @samp{.=.+4} is the same as saying
3261 @ifclear no-space-dir
3270 @node Symbol Attributes
3271 @section Symbol Attributes
3273 @cindex symbol attributes
3274 @cindex attributes, symbol
3275 Every symbol has, as well as its name, the attributes ``Value'' and
3276 ``Type''. Depending on output format, symbols can also have auxiliary
3279 The detailed definitions are in @file{a.out.h}.
3282 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3283 all these attributes, and probably won't warn you. This makes the
3284 symbol an externally defined symbol, which is generally what you
3288 * Symbol Value:: Value
3289 * Symbol Type:: Type
3292 * a.out Symbols:: Symbol Attributes: @code{a.out}
3296 * a.out Symbols:: Symbol Attributes: @code{a.out}
3299 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3304 * COFF Symbols:: Symbol Attributes for COFF
3307 * SOM Symbols:: Symbol Attributes for SOM
3314 @cindex value of a symbol
3315 @cindex symbol value
3316 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3317 location in the text, data, bss or absolute sections the value is the
3318 number of addresses from the start of that section to the label.
3319 Naturally for text, data and bss sections the value of a symbol changes
3320 as @code{@value{LD}} changes section base addresses during linking. Absolute
3321 symbols' values do not change during linking: that is why they are
3324 The value of an undefined symbol is treated in a special way. If it is
3325 0 then the symbol is not defined in this assembler source file, and
3326 @code{@value{LD}} tries to determine its value from other files linked into the
3327 same program. You make this kind of symbol simply by mentioning a symbol
3328 name without defining it. A non-zero value represents a @code{.comm}
3329 common declaration. The value is how much common storage to reserve, in
3330 bytes (addresses). The symbol refers to the first address of the
3336 @cindex type of a symbol
3338 The type attribute of a symbol contains relocation (section)
3339 information, any flag settings indicating that a symbol is external, and
3340 (optionally), other information for linkers and debuggers. The exact
3341 format depends on the object-code output format in use.
3346 @c The following avoids a "widow" subsection title. @group would be
3347 @c better if it were available outside examples.
3350 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3352 @cindex @code{b.out} symbol attributes
3353 @cindex symbol attributes, @code{b.out}
3354 These symbol attributes appear only when @command{@value{AS}} is configured for
3355 one of the Berkeley-descended object output formats---@code{a.out} or
3361 @subsection Symbol Attributes: @code{a.out}
3363 @cindex @code{a.out} symbol attributes
3364 @cindex symbol attributes, @code{a.out}
3370 @subsection Symbol Attributes: @code{a.out}
3372 @cindex @code{a.out} symbol attributes
3373 @cindex symbol attributes, @code{a.out}
3377 * Symbol Desc:: Descriptor
3378 * Symbol Other:: Other
3382 @subsubsection Descriptor
3384 @cindex descriptor, of @code{a.out} symbol
3385 This is an arbitrary 16-bit value. You may establish a symbol's
3386 descriptor value by using a @code{.desc} statement
3387 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3388 @command{@value{AS}}.
3391 @subsubsection Other
3393 @cindex other attribute, of @code{a.out} symbol
3394 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3399 @subsection Symbol Attributes for COFF
3401 @cindex COFF symbol attributes
3402 @cindex symbol attributes, COFF
3404 The COFF format supports a multitude of auxiliary symbol attributes;
3405 like the primary symbol attributes, they are set between @code{.def} and
3406 @code{.endef} directives.
3408 @subsubsection Primary Attributes
3410 @cindex primary attributes, COFF symbols
3411 The symbol name is set with @code{.def}; the value and type,
3412 respectively, with @code{.val} and @code{.type}.
3414 @subsubsection Auxiliary Attributes
3416 @cindex auxiliary attributes, COFF symbols
3417 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3418 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3419 table information for COFF.
3424 @subsection Symbol Attributes for SOM
3426 @cindex SOM symbol attributes
3427 @cindex symbol attributes, SOM
3429 The SOM format for the HPPA supports a multitude of symbol attributes set with
3430 the @code{.EXPORT} and @code{.IMPORT} directives.
3432 The attributes are described in @cite{HP9000 Series 800 Assembly
3433 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3434 @code{EXPORT} assembler directive documentation.
3438 @chapter Expressions
3442 @cindex numeric values
3443 An @dfn{expression} specifies an address or numeric value.
3444 Whitespace may precede and/or follow an expression.
3446 The result of an expression must be an absolute number, or else an offset into
3447 a particular section. If an expression is not absolute, and there is not
3448 enough information when @command{@value{AS}} sees the expression to know its
3449 section, a second pass over the source program might be necessary to interpret
3450 the expression---but the second pass is currently not implemented.
3451 @command{@value{AS}} aborts with an error message in this situation.
3454 * Empty Exprs:: Empty Expressions
3455 * Integer Exprs:: Integer Expressions
3459 @section Empty Expressions
3461 @cindex empty expressions
3462 @cindex expressions, empty
3463 An empty expression has no value: it is just whitespace or null.
3464 Wherever an absolute expression is required, you may omit the
3465 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3466 is compatible with other assemblers.
3469 @section Integer Expressions
3471 @cindex integer expressions
3472 @cindex expressions, integer
3473 An @dfn{integer expression} is one or more @emph{arguments} delimited
3474 by @emph{operators}.
3477 * Arguments:: Arguments
3478 * Operators:: Operators
3479 * Prefix Ops:: Prefix Operators
3480 * Infix Ops:: Infix Operators
3484 @subsection Arguments
3486 @cindex expression arguments
3487 @cindex arguments in expressions
3488 @cindex operands in expressions
3489 @cindex arithmetic operands
3490 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3491 contexts arguments are sometimes called ``arithmetic operands''. In
3492 this manual, to avoid confusing them with the ``instruction operands'' of
3493 the machine language, we use the term ``argument'' to refer to parts of
3494 expressions only, reserving the word ``operand'' to refer only to machine
3495 instruction operands.
3497 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3498 @var{section} is one of text, data, bss, absolute,
3499 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3502 Numbers are usually integers.
3504 A number can be a flonum or bignum. In this case, you are warned
3505 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3506 these 32 bits are an integer. You may write integer-manipulating
3507 instructions that act on exotic constants, compatible with other
3510 @cindex subexpressions
3511 Subexpressions are a left parenthesis @samp{(} followed by an integer
3512 expression, followed by a right parenthesis @samp{)}; or a prefix
3513 operator followed by an argument.
3516 @subsection Operators
3518 @cindex operators, in expressions
3519 @cindex arithmetic functions
3520 @cindex functions, in expressions
3521 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3522 operators are followed by an argument. Infix operators appear
3523 between their arguments. Operators may be preceded and/or followed by
3527 @subsection Prefix Operator
3529 @cindex prefix operators
3530 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3531 one argument, which must be absolute.
3533 @c the tex/end tex stuff surrounding this small table is meant to make
3534 @c it align, on the printed page, with the similar table in the next
3535 @c section (which is inside an enumerate).
3537 \global\advance\leftskip by \itemindent
3542 @dfn{Negation}. Two's complement negation.
3544 @dfn{Complementation}. Bitwise not.
3548 \global\advance\leftskip by -\itemindent
3552 @subsection Infix Operators
3554 @cindex infix operators
3555 @cindex operators, permitted arguments
3556 @dfn{Infix operators} take two arguments, one on either side. Operators
3557 have precedence, but operations with equal precedence are performed left
3558 to right. Apart from @code{+} or @option{-}, both arguments must be
3559 absolute, and the result is absolute.
3562 @cindex operator precedence
3563 @cindex precedence of operators
3570 @dfn{Multiplication}.
3573 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3580 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3584 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3588 Intermediate precedence
3593 @dfn{Bitwise Inclusive Or}.
3599 @dfn{Bitwise Exclusive Or}.
3602 @dfn{Bitwise Or Not}.
3609 @cindex addition, permitted arguments
3610 @cindex plus, permitted arguments
3611 @cindex arguments for addition
3613 @dfn{Addition}. If either argument is absolute, the result has the section of
3614 the other argument. You may not add together arguments from different
3617 @cindex subtraction, permitted arguments
3618 @cindex minus, permitted arguments
3619 @cindex arguments for subtraction
3621 @dfn{Subtraction}. If the right argument is absolute, the
3622 result has the section of the left argument.
3623 If both arguments are in the same section, the result is absolute.
3624 You may not subtract arguments from different sections.
3625 @c FIXME is there still something useful to say about undefined - undefined ?
3627 @cindex comparison expressions
3628 @cindex expressions, comparison
3632 @dfn{Is Not Equal To}
3636 @dfn{Is Greater Than}
3638 @dfn{Is Greater Than Or Equal To}
3640 @dfn{Is Less Than Or Equal To}
3642 The comparison operators can be used as infix operators. A true results has a
3643 value of -1 whereas a false result has a value of 0. Note, these operators
3644 perform signed comparisons.
3647 @item Lowest Precedence
3656 These two logical operations can be used to combine the results of sub
3657 expressions. Note, unlike the comparison operators a true result returns a
3658 value of 1 but a false results does still return 0. Also note that the logical
3659 or operator has a slightly lower precedence than logical and.
3664 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3665 address; you can only have a defined section in one of the two arguments.
3668 @chapter Assembler Directives
3670 @cindex directives, machine independent
3671 @cindex pseudo-ops, machine independent
3672 @cindex machine independent directives
3673 All assembler directives have names that begin with a period (@samp{.}).
3674 The rest of the name is letters, usually in lower case.
3676 This chapter discusses directives that are available regardless of the
3677 target machine configuration for the @sc{gnu} assembler.
3679 Some machine configurations provide additional directives.
3680 @xref{Machine Dependencies}.
3683 @ifset machine-directives
3684 @xref{Machine Dependencies} for additional directives.
3689 * Abort:: @code{.abort}
3691 * ABORT:: @code{.ABORT}
3694 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3695 * Altmacro:: @code{.altmacro}
3696 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3697 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3698 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3699 * Byte:: @code{.byte @var{expressions}}
3700 * Comm:: @code{.comm @var{symbol} , @var{length} }
3702 * CFI directives:: @code{.cfi_startproc}, @code{.cfi_endproc}, etc.
3704 * Data:: @code{.data @var{subsection}}
3706 * Def:: @code{.def @var{name}}
3709 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3715 * Double:: @code{.double @var{flonums}}
3716 * Eject:: @code{.eject}
3717 * Else:: @code{.else}
3718 * Elseif:: @code{.elseif}
3721 * Endef:: @code{.endef}
3724 * Endfunc:: @code{.endfunc}
3725 * Endif:: @code{.endif}
3726 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3727 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3729 * Error:: @code{.error @var{string}}
3730 * Exitm:: @code{.exitm}
3731 * Extern:: @code{.extern}
3732 * Fail:: @code{.fail}
3733 @ifclear no-file-dir
3734 * File:: @code{.file @var{string}}
3737 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3738 * Float:: @code{.float @var{flonums}}
3739 * Func:: @code{.func}
3740 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3742 * Hidden:: @code{.hidden @var{names}}
3745 * hword:: @code{.hword @var{expressions}}
3746 * Ident:: @code{.ident}
3747 * If:: @code{.if @var{absolute expression}}
3748 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3749 * Include:: @code{.include "@var{file}"}
3750 * Int:: @code{.int @var{expressions}}
3752 * Internal:: @code{.internal @var{names}}
3755 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3756 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3757 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3758 * Lflags:: @code{.lflags}
3759 @ifclear no-line-dir
3760 * Line:: @code{.line @var{line-number}}
3763 * Ln:: @code{.ln @var{line-number}}
3764 * Linkonce:: @code{.linkonce [@var{type}]}
3765 * List:: @code{.list}
3766 * Long:: @code{.long @var{expressions}}
3768 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3771 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3772 * MRI:: @code{.mri @var{val}}
3773 * Noaltmacro:: @code{.noaltmacro}
3774 * Nolist:: @code{.nolist}
3775 * Octa:: @code{.octa @var{bignums}}
3776 * Org:: @code{.org @var{new-lc} , @var{fill}}
3777 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3779 * PopSection:: @code{.popsection}
3780 * Previous:: @code{.previous}
3783 * Print:: @code{.print @var{string}}
3785 * Protected:: @code{.protected @var{names}}
3788 * Psize:: @code{.psize @var{lines}, @var{columns}}
3789 * Purgem:: @code{.purgem @var{name}}
3791 * PushSection:: @code{.pushsection @var{name}}
3794 * Quad:: @code{.quad @var{bignums}}
3795 * Rept:: @code{.rept @var{count}}
3796 * Sbttl:: @code{.sbttl "@var{subheading}"}
3798 * Scl:: @code{.scl @var{class}}
3801 * Section:: @code{.section @var{name}}
3804 * Set:: @code{.set @var{symbol}, @var{expression}}
3805 * Short:: @code{.short @var{expressions}}
3806 * Single:: @code{.single @var{flonums}}
3808 * Size:: @code{.size [@var{name} , @var{expression}]}
3811 * Skip:: @code{.skip @var{size} , @var{fill}}
3812 * Sleb128:: @code{.sleb128 @var{expressions}}
3813 * Space:: @code{.space @var{size} , @var{fill}}
3815 * Stab:: @code{.stabd, .stabn, .stabs}
3818 * String:: @code{.string "@var{str}"}
3819 * Struct:: @code{.struct @var{expression}}
3821 * SubSection:: @code{.subsection}
3822 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3826 * Tag:: @code{.tag @var{structname}}
3829 * Text:: @code{.text @var{subsection}}
3830 * Title:: @code{.title "@var{heading}"}
3832 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3835 * Uleb128:: @code{.uleb128 @var{expressions}}
3837 * Val:: @code{.val @var{addr}}
3841 * Version:: @code{.version "@var{string}"}
3842 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3843 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3846 * Warning:: @code{.warning @var{string}}
3847 * Weak:: @code{.weak @var{names}}
3848 * Word:: @code{.word @var{expressions}}
3849 * Deprecated:: Deprecated Directives
3853 @section @code{.abort}
3855 @cindex @code{abort} directive
3856 @cindex stopping the assembly
3857 This directive stops the assembly immediately. It is for
3858 compatibility with other assemblers. The original idea was that the
3859 assembly language source would be piped into the assembler. If the sender
3860 of the source quit, it could use this directive tells @command{@value{AS}} to
3861 quit also. One day @code{.abort} will not be supported.
3865 @section @code{.ABORT}
3867 @cindex @code{ABORT} directive
3868 When producing COFF output, @command{@value{AS}} accepts this directive as a
3869 synonym for @samp{.abort}.
3872 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3878 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3880 @cindex padding the location counter
3881 @cindex @code{align} directive
3882 Pad the location counter (in the current subsection) to a particular storage
3883 boundary. The first expression (which must be absolute) is the alignment
3884 required, as described below.
3886 The second expression (also absolute) gives the fill value to be stored in the
3887 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3888 padding bytes are normally zero. However, on some systems, if the section is
3889 marked as containing code and the fill value is omitted, the space is filled
3890 with no-op instructions.
3892 The third expression is also absolute, and is also optional. If it is present,
3893 it is the maximum number of bytes that should be skipped by this alignment
3894 directive. If doing the alignment would require skipping more bytes than the
3895 specified maximum, then the alignment is not done at all. You can omit the
3896 fill value (the second argument) entirely by simply using two commas after the
3897 required alignment; this can be useful if you want the alignment to be filled
3898 with no-op instructions when appropriate.
3900 The way the required alignment is specified varies from system to system.
3901 For the a29k, arc, hppa, i386 using ELF, i860, iq2000, m68k, m88k, or32,
3902 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
3903 alignment request in bytes. For example @samp{.align 8} advances
3904 the location counter until it is a multiple of 8. If the location counter
3905 is already a multiple of 8, no change is needed. For the tic54x, the
3906 first expression is the alignment request in words.
3908 For other systems, including the i386 using a.out format, and the arm and
3909 strongarm, it is the
3910 number of low-order zero bits the location counter must have after
3911 advancement. For example @samp{.align 3} advances the location
3912 counter until it a multiple of 8. If the location counter is already a
3913 multiple of 8, no change is needed.
3915 This inconsistency is due to the different behaviors of the various
3916 native assemblers for these systems which GAS must emulate.
3917 GAS also provides @code{.balign} and @code{.p2align} directives,
3918 described later, which have a consistent behavior across all
3919 architectures (but are specific to GAS).
3922 @section @code{.ascii "@var{string}"}@dots{}
3924 @cindex @code{ascii} directive
3925 @cindex string literals
3926 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3927 separated by commas. It assembles each string (with no automatic
3928 trailing zero byte) into consecutive addresses.
3931 @section @code{.asciz "@var{string}"}@dots{}
3933 @cindex @code{asciz} directive
3934 @cindex zero-terminated strings
3935 @cindex null-terminated strings
3936 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3937 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3940 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3942 @cindex padding the location counter given number of bytes
3943 @cindex @code{balign} directive
3944 Pad the location counter (in the current subsection) to a particular
3945 storage boundary. The first expression (which must be absolute) is the
3946 alignment request in bytes. For example @samp{.balign 8} advances
3947 the location counter until it is a multiple of 8. If the location counter
3948 is already a multiple of 8, no change is needed.
3950 The second expression (also absolute) gives the fill value to be stored in the
3951 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3952 padding bytes are normally zero. However, on some systems, if the section is
3953 marked as containing code and the fill value is omitted, the space is filled
3954 with no-op instructions.
3956 The third expression is also absolute, and is also optional. If it is present,
3957 it is the maximum number of bytes that should be skipped by this alignment
3958 directive. If doing the alignment would require skipping more bytes than the
3959 specified maximum, then the alignment is not done at all. You can omit the
3960 fill value (the second argument) entirely by simply using two commas after the
3961 required alignment; this can be useful if you want the alignment to be filled
3962 with no-op instructions when appropriate.
3964 @cindex @code{balignw} directive
3965 @cindex @code{balignl} directive
3966 The @code{.balignw} and @code{.balignl} directives are variants of the
3967 @code{.balign} directive. The @code{.balignw} directive treats the fill
3968 pattern as a two byte word value. The @code{.balignl} directives treats the
3969 fill pattern as a four byte longword value. For example, @code{.balignw
3970 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3971 filled in with the value 0x368d (the exact placement of the bytes depends upon
3972 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3976 @section @code{.byte @var{expressions}}
3978 @cindex @code{byte} directive
3979 @cindex integers, one byte
3980 @code{.byte} expects zero or more expressions, separated by commas.
3981 Each expression is assembled into the next byte.
3984 @section @code{.comm @var{symbol} , @var{length} }
3986 @cindex @code{comm} directive
3987 @cindex symbol, common
3988 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3989 common symbol in one object file may be merged with a defined or common symbol
3990 of the same name in another object file. If @code{@value{LD}} does not see a
3991 definition for the symbol--just one or more common symbols--then it will
3992 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3993 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3994 the same name, and they do not all have the same size, it will allocate space
3995 using the largest size.
3998 When using ELF, the @code{.comm} directive takes an optional third argument.
3999 This is the desired alignment of the symbol, specified as a byte boundary (for
4000 example, an alignment of 16 means that the least significant 4 bits of the
4001 address should be zero). The alignment must be an absolute expression, and it
4002 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
4003 for the common symbol, it will use the alignment when placing the symbol. If
4004 no alignment is specified, @command{@value{AS}} will set the alignment to the
4005 largest power of two less than or equal to the size of the symbol, up to a
4010 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4011 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4014 @node CFI directives
4015 @section @code{.cfi_startproc}
4016 @cindex @code{cfi_startproc} directive
4017 @code{.cfi_startproc} is used at the beginning of each function that
4018 should have an entry in @code{.eh_frame}. It initializes some internal
4019 data structures and emits architecture dependent initial CFI instructions.
4020 Don't forget to close the function by
4021 @code{.cfi_endproc}.
4023 @section @code{.cfi_endproc}
4024 @cindex @code{cfi_endproc} directive
4025 @code{.cfi_endproc} is used at the end of a function where it closes its
4026 unwind entry previously opened by
4027 @code{.cfi_startproc}. and emits it to @code{.eh_frame}.
4029 @section @code{.cfi_def_cfa @var{register}, @var{offset}}
4030 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4031 address from @var{register} and add @var{offset} to it}.
4033 @section @code{.cfi_def_cfa_register @var{register}}
4034 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4035 now on @var{register} will be used instead of the old one. Offset
4038 @section @code{.cfi_def_cfa_offset @var{offset}}
4039 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4040 remains the same, but @var{offset} is new. Note that it is the
4041 absolute offset that will be added to a defined register to compute
4044 @section @code{.cfi_adjust_cfa_offset @var{offset}}
4045 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4046 value that is added/substracted from the previous offset.
4048 @section @code{.cfi_offset @var{register}, @var{offset}}
4049 Previous value of @var{register} is saved at offset @var{offset} from
4052 @section @code{.cfi_rel_offset @var{register}, @var{offset}}
4053 Previous value of @var{register} is saved at offset @var{offset} from
4054 the current CFA register. This is transformed to @code{.cfi_offset}
4055 using the known displacement of the CFA register from the CFA.
4056 This is often easier to use, because the number will match the
4057 code it's annotating.
4059 @section @code{.cfi_window_save}
4060 SPARC register window has been saved.
4062 @section @code{.cfi_escape} @var{expression}[, @dots{}]
4063 Allows the user to add arbitrary bytes to the unwind info. One
4064 might use this to add OS-specific CFI opcodes, or generic CFI
4065 opcodes that GAS does not yet support.
4068 @section @code{.data @var{subsection}}
4070 @cindex @code{data} directive
4071 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4072 end of the data subsection numbered @var{subsection} (which is an
4073 absolute expression). If @var{subsection} is omitted, it defaults
4078 @section @code{.def @var{name}}
4080 @cindex @code{def} directive
4081 @cindex COFF symbols, debugging
4082 @cindex debugging COFF symbols
4083 Begin defining debugging information for a symbol @var{name}; the
4084 definition extends until the @code{.endef} directive is encountered.
4087 This directive is only observed when @command{@value{AS}} is configured for COFF
4088 format output; when producing @code{b.out}, @samp{.def} is recognized,
4095 @section @code{.desc @var{symbol}, @var{abs-expression}}
4097 @cindex @code{desc} directive
4098 @cindex COFF symbol descriptor
4099 @cindex symbol descriptor, COFF
4100 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4101 to the low 16 bits of an absolute expression.
4104 The @samp{.desc} directive is not available when @command{@value{AS}} is
4105 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4106 object format. For the sake of compatibility, @command{@value{AS}} accepts
4107 it, but produces no output, when configured for COFF.
4113 @section @code{.dim}
4115 @cindex @code{dim} directive
4116 @cindex COFF auxiliary symbol information
4117 @cindex auxiliary symbol information, COFF
4118 This directive is generated by compilers to include auxiliary debugging
4119 information in the symbol table. It is only permitted inside
4120 @code{.def}/@code{.endef} pairs.
4123 @samp{.dim} is only meaningful when generating COFF format output; when
4124 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4130 @section @code{.double @var{flonums}}
4132 @cindex @code{double} directive
4133 @cindex floating point numbers (double)
4134 @code{.double} expects zero or more flonums, separated by commas. It
4135 assembles floating point numbers.
4137 The exact kind of floating point numbers emitted depends on how
4138 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4142 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4143 in @sc{ieee} format.
4148 @section @code{.eject}
4150 @cindex @code{eject} directive
4151 @cindex new page, in listings
4152 @cindex page, in listings
4153 @cindex listing control: new page
4154 Force a page break at this point, when generating assembly listings.
4157 @section @code{.else}
4159 @cindex @code{else} directive
4160 @code{.else} is part of the @command{@value{AS}} support for conditional
4161 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
4162 of code to be assembled if the condition for the preceding @code{.if}
4166 @section @code{.elseif}
4168 @cindex @code{elseif} directive
4169 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4170 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
4171 @code{.if} block that would otherwise fill the entire @code{.else} section.
4174 @section @code{.end}
4176 @cindex @code{end} directive
4177 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4178 process anything in the file past the @code{.end} directive.
4182 @section @code{.endef}
4184 @cindex @code{endef} directive
4185 This directive flags the end of a symbol definition begun with
4189 @samp{.endef} is only meaningful when generating COFF format output; if
4190 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4191 directive but ignores it.
4196 @section @code{.endfunc}
4197 @cindex @code{endfunc} directive
4198 @code{.endfunc} marks the end of a function specified with @code{.func}.
4201 @section @code{.endif}
4203 @cindex @code{endif} directive
4204 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4205 it marks the end of a block of code that is only assembled
4206 conditionally. @xref{If,,@code{.if}}.
4209 @section @code{.equ @var{symbol}, @var{expression}}
4211 @cindex @code{equ} directive
4212 @cindex assigning values to symbols
4213 @cindex symbols, assigning values to
4214 This directive sets the value of @var{symbol} to @var{expression}.
4215 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
4218 The syntax for @code{equ} on the HPPA is
4219 @samp{@var{symbol} .equ @var{expression}}.
4223 @section @code{.equiv @var{symbol}, @var{expression}}
4224 @cindex @code{equiv} directive
4225 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4226 the assembler will signal an error if @var{symbol} is already defined. Note a
4227 symbol which has been referenced but not actually defined is considered to be
4230 Except for the contents of the error message, this is roughly equivalent to
4239 @section @code{.err}
4240 @cindex @code{err} directive
4241 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4242 message and, unless the @option{-Z} option was used, it will not generate an
4243 object file. This can be used to signal error an conditionally compiled code.
4246 @section @code{.error "@var{string}"}
4247 @cindex error directive
4249 Similarly to @code{.err}, this directive emits an error, but you can specify a
4250 string that will be emitted as the error message. If you don't specify the
4251 message, it defaults to @code{".error directive invoked in source file"}.
4252 @xref{Errors, ,Error and Warning Messages}.
4255 .error "This code has not been assembled and tested."
4259 @section @code{.exitm}
4260 Exit early from the current macro definition. @xref{Macro}.
4263 @section @code{.extern}
4265 @cindex @code{extern} directive
4266 @code{.extern} is accepted in the source program---for compatibility
4267 with other assemblers---but it is ignored. @command{@value{AS}} treats
4268 all undefined symbols as external.
4271 @section @code{.fail @var{expression}}
4273 @cindex @code{fail} directive
4274 Generates an error or a warning. If the value of the @var{expression} is 500
4275 or more, @command{@value{AS}} will print a warning message. If the value is less
4276 than 500, @command{@value{AS}} will print an error message. The message will
4277 include the value of @var{expression}. This can occasionally be useful inside
4278 complex nested macros or conditional assembly.
4280 @ifclear no-file-dir
4282 @section @code{.file @var{string}}
4284 @cindex @code{file} directive
4285 @cindex logical file name
4286 @cindex file name, logical
4287 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4288 file. @var{string} is the new file name. In general, the filename is
4289 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4290 to specify an empty file name, you must give the quotes--@code{""}. This
4291 statement may go away in future: it is only recognized to be compatible with
4292 old @command{@value{AS}} programs.
4294 In some configurations of @command{@value{AS}}, @code{.file} has already been
4295 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4300 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4302 @cindex @code{fill} directive
4303 @cindex writing patterns in memory
4304 @cindex patterns, writing in memory
4305 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4306 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4307 may be zero or more. @var{Size} may be zero or more, but if it is
4308 more than 8, then it is deemed to have the value 8, compatible with
4309 other people's assemblers. The contents of each @var{repeat} bytes
4310 is taken from an 8-byte number. The highest order 4 bytes are
4311 zero. The lowest order 4 bytes are @var{value} rendered in the
4312 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4313 Each @var{size} bytes in a repetition is taken from the lowest order
4314 @var{size} bytes of this number. Again, this bizarre behavior is
4315 compatible with other people's assemblers.
4317 @var{size} and @var{value} are optional.
4318 If the second comma and @var{value} are absent, @var{value} is
4319 assumed zero. If the first comma and following tokens are absent,
4320 @var{size} is assumed to be 1.
4323 @section @code{.float @var{flonums}}
4325 @cindex floating point numbers (single)
4326 @cindex @code{float} directive
4327 This directive assembles zero or more flonums, separated by commas. It
4328 has the same effect as @code{.single}.
4330 The exact kind of floating point numbers emitted depends on how
4331 @command{@value{AS}} is configured.
4332 @xref{Machine Dependencies}.
4336 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4337 in @sc{ieee} format.
4342 @section @code{.func @var{name}[,@var{label}]}
4343 @cindex @code{func} directive
4344 @code{.func} emits debugging information to denote function @var{name}, and
4345 is ignored unless the file is assembled with debugging enabled.
4346 Only @samp{--gstabs[+]} is currently supported.
4347 @var{label} is the entry point of the function and if omitted @var{name}
4348 prepended with the @samp{leading char} is used.
4349 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4350 All functions are currently defined to have @code{void} return type.
4351 The function must be terminated with @code{.endfunc}.
4354 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4356 @cindex @code{global} directive
4357 @cindex symbol, making visible to linker
4358 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4359 @var{symbol} in your partial program, its value is made available to
4360 other partial programs that are linked with it. Otherwise,
4361 @var{symbol} takes its attributes from a symbol of the same name
4362 from another file linked into the same program.
4364 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4365 compatibility with other assemblers.
4368 On the HPPA, @code{.global} is not always enough to make it accessible to other
4369 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4370 @xref{HPPA Directives,, HPPA Assembler Directives}.
4375 @section @code{.hidden @var{names}}
4377 @cindex @code{hidden} directive
4379 This is one of the ELF visibility directives. The other two are
4380 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4381 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4383 This directive overrides the named symbols default visibility (which is set by
4384 their binding: local, global or weak). The directive sets the visibility to
4385 @code{hidden} which means that the symbols are not visible to other components.
4386 Such symbols are always considered to be @code{protected} as well.
4390 @section @code{.hword @var{expressions}}
4392 @cindex @code{hword} directive
4393 @cindex integers, 16-bit
4394 @cindex numbers, 16-bit
4395 @cindex sixteen bit integers
4396 This expects zero or more @var{expressions}, and emits
4397 a 16 bit number for each.
4400 This directive is a synonym for @samp{.short}; depending on the target
4401 architecture, it may also be a synonym for @samp{.word}.
4405 This directive is a synonym for @samp{.short}.
4408 This directive is a synonym for both @samp{.short} and @samp{.word}.
4413 @section @code{.ident}
4415 @cindex @code{ident} directive
4416 This directive is used by some assemblers to place tags in object files.
4417 @command{@value{AS}} simply accepts the directive for source-file
4418 compatibility with such assemblers, but does not actually emit anything
4422 @section @code{.if @var{absolute expression}}
4424 @cindex conditional assembly
4425 @cindex @code{if} directive
4426 @code{.if} marks the beginning of a section of code which is only
4427 considered part of the source program being assembled if the argument
4428 (which must be an @var{absolute expression}) is non-zero. The end of
4429 the conditional section of code must be marked by @code{.endif}
4430 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4431 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4432 If you have several conditions to check, @code{.elseif} may be used to avoid
4433 nesting blocks if/else within each subsequent @code{.else} block.
4435 The following variants of @code{.if} are also supported:
4437 @cindex @code{ifdef} directive
4438 @item .ifdef @var{symbol}
4439 Assembles the following section of code if the specified @var{symbol}
4440 has been defined. Note a symbol which has been referenced but not yet defined
4441 is considered to be undefined.
4443 @cindex @code{ifc} directive
4444 @item .ifc @var{string1},@var{string2}
4445 Assembles the following section of code if the two strings are the same. The
4446 strings may be optionally quoted with single quotes. If they are not quoted,
4447 the first string stops at the first comma, and the second string stops at the
4448 end of the line. Strings which contain whitespace should be quoted. The
4449 string comparison is case sensitive.
4451 @cindex @code{ifeq} directive
4452 @item .ifeq @var{absolute expression}
4453 Assembles the following section of code if the argument is zero.
4455 @cindex @code{ifeqs} directive
4456 @item .ifeqs @var{string1},@var{string2}
4457 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4459 @cindex @code{ifge} directive
4460 @item .ifge @var{absolute expression}
4461 Assembles the following section of code if the argument is greater than or
4464 @cindex @code{ifgt} directive
4465 @item .ifgt @var{absolute expression}
4466 Assembles the following section of code if the argument is greater than zero.
4468 @cindex @code{ifle} directive
4469 @item .ifle @var{absolute expression}
4470 Assembles the following section of code if the argument is less than or equal
4473 @cindex @code{iflt} directive
4474 @item .iflt @var{absolute expression}
4475 Assembles the following section of code if the argument is less than zero.
4477 @cindex @code{ifnc} directive
4478 @item .ifnc @var{string1},@var{string2}.
4479 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4480 following section of code if the two strings are not the same.
4482 @cindex @code{ifndef} directive
4483 @cindex @code{ifnotdef} directive
4484 @item .ifndef @var{symbol}
4485 @itemx .ifnotdef @var{symbol}
4486 Assembles the following section of code if the specified @var{symbol}
4487 has not been defined. Both spelling variants are equivalent. Note a symbol
4488 which has been referenced but not yet defined is considered to be undefined.
4490 @cindex @code{ifne} directive
4491 @item .ifne @var{absolute expression}
4492 Assembles the following section of code if the argument is not equal to zero
4493 (in other words, this is equivalent to @code{.if}).
4495 @cindex @code{ifnes} directive
4496 @item .ifnes @var{string1},@var{string2}
4497 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4498 following section of code if the two strings are not the same.
4502 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4504 @cindex @code{incbin} directive
4505 @cindex binary files, including
4506 The @code{incbin} directive includes @var{file} verbatim at the current
4507 location. You can control the search paths used with the @samp{-I} command-line
4508 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4511 The @var{skip} argument skips a number of bytes from the start of the
4512 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4513 read. Note that the data is not aligned in any way, so it is the user's
4514 responsibility to make sure that proper alignment is provided both before and
4515 after the @code{incbin} directive.
4518 @section @code{.include "@var{file}"}
4520 @cindex @code{include} directive
4521 @cindex supporting files, including
4522 @cindex files, including
4523 This directive provides a way to include supporting files at specified
4524 points in your source program. The code from @var{file} is assembled as
4525 if it followed the point of the @code{.include}; when the end of the
4526 included file is reached, assembly of the original file continues. You
4527 can control the search paths used with the @samp{-I} command-line option
4528 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4532 @section @code{.int @var{expressions}}
4534 @cindex @code{int} directive
4535 @cindex integers, 32-bit
4536 Expect zero or more @var{expressions}, of any section, separated by commas.
4537 For each expression, emit a number that, at run time, is the value of that
4538 expression. The byte order and bit size of the number depends on what kind
4539 of target the assembly is for.
4543 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4544 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
4551 @section @code{.internal @var{names}}
4553 @cindex @code{internal} directive
4555 This is one of the ELF visibility directives. The other two are
4556 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4557 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4559 This directive overrides the named symbols default visibility (which is set by
4560 their binding: local, global or weak). The directive sets the visibility to
4561 @code{internal} which means that the symbols are considered to be @code{hidden}
4562 (i.e., not visible to other components), and that some extra, processor specific
4563 processing must also be performed upon the symbols as well.
4567 @section @code{.irp @var{symbol},@var{values}}@dots{}
4569 @cindex @code{irp} directive
4570 Evaluate a sequence of statements assigning different values to @var{symbol}.
4571 The sequence of statements starts at the @code{.irp} directive, and is
4572 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4573 set to @var{value}, and the sequence of statements is assembled. If no
4574 @var{value} is listed, the sequence of statements is assembled once, with
4575 @var{symbol} set to the null string. To refer to @var{symbol} within the
4576 sequence of statements, use @var{\symbol}.
4578 For example, assembling
4586 is equivalent to assembling
4595 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4597 @cindex @code{irpc} directive
4598 Evaluate a sequence of statements assigning different values to @var{symbol}.
4599 The sequence of statements starts at the @code{.irpc} directive, and is
4600 terminated by an @code{.endr} directive. For each character in @var{value},
4601 @var{symbol} is set to the character, and the sequence of statements is
4602 assembled. If no @var{value} is listed, the sequence of statements is
4603 assembled once, with @var{symbol} set to the null string. To refer to
4604 @var{symbol} within the sequence of statements, use @var{\symbol}.
4606 For example, assembling
4614 is equivalent to assembling
4623 @section @code{.lcomm @var{symbol} , @var{length}}
4625 @cindex @code{lcomm} directive
4626 @cindex local common symbols
4627 @cindex symbols, local common
4628 Reserve @var{length} (an absolute expression) bytes for a local common
4629 denoted by @var{symbol}. The section and value of @var{symbol} are
4630 those of the new local common. The addresses are allocated in the bss
4631 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4632 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4633 not visible to @code{@value{LD}}.
4636 Some targets permit a third argument to be used with @code{.lcomm}. This
4637 argument specifies the desired alignment of the symbol in the bss section.
4641 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4642 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4646 @section @code{.lflags}
4648 @cindex @code{lflags} directive (ignored)
4649 @command{@value{AS}} accepts this directive, for compatibility with other
4650 assemblers, but ignores it.
4652 @ifclear no-line-dir
4654 @section @code{.line @var{line-number}}
4656 @cindex @code{line} directive
4660 @section @code{.ln @var{line-number}}
4662 @cindex @code{ln} directive
4664 @cindex logical line number
4666 Change the logical line number. @var{line-number} must be an absolute
4667 expression. The next line has that logical line number. Therefore any other
4668 statements on the current line (after a statement separator character) are
4669 reported as on logical line number @var{line-number} @minus{} 1. One day
4670 @command{@value{AS}} will no longer support this directive: it is recognized only
4671 for compatibility with existing assembler programs.
4675 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4676 not available; use the synonym @code{.ln} in that context.
4681 @ifclear no-line-dir
4682 Even though this is a directive associated with the @code{a.out} or
4683 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4684 when producing COFF output, and treats @samp{.line} as though it
4685 were the COFF @samp{.ln} @emph{if} it is found outside a
4686 @code{.def}/@code{.endef} pair.
4688 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4689 used by compilers to generate auxiliary symbol information for
4694 @section @code{.linkonce [@var{type}]}
4696 @cindex @code{linkonce} directive
4697 @cindex common sections
4698 Mark the current section so that the linker only includes a single copy of it.
4699 This may be used to include the same section in several different object files,
4700 but ensure that the linker will only include it once in the final output file.
4701 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4702 Duplicate sections are detected based on the section name, so it should be
4705 This directive is only supported by a few object file formats; as of this
4706 writing, the only object file format which supports it is the Portable
4707 Executable format used on Windows NT.
4709 The @var{type} argument is optional. If specified, it must be one of the
4710 following strings. For example:
4714 Not all types may be supported on all object file formats.
4718 Silently discard duplicate sections. This is the default.
4721 Warn if there are duplicate sections, but still keep only one copy.
4724 Warn if any of the duplicates have different sizes.
4727 Warn if any of the duplicates do not have exactly the same contents.
4731 @section @code{.ln @var{line-number}}
4733 @cindex @code{ln} directive
4734 @ifclear no-line-dir
4735 @samp{.ln} is a synonym for @samp{.line}.
4738 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4739 must be an absolute expression. The next line has that logical
4740 line number, so any other statements on the current line (after a
4741 statement separator character @code{;}) are reported as on logical
4742 line number @var{line-number} @minus{} 1.
4745 This directive is accepted, but ignored, when @command{@value{AS}} is
4746 configured for @code{b.out}; its effect is only associated with COFF
4752 @section @code{.mri @var{val}}
4754 @cindex @code{mri} directive
4755 @cindex MRI mode, temporarily
4756 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4757 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4758 affects code assembled until the next @code{.mri} directive, or until the end
4759 of the file. @xref{M, MRI mode, MRI mode}.
4762 @section @code{.list}
4764 @cindex @code{list} directive
4765 @cindex listing control, turning on
4766 Control (in conjunction with the @code{.nolist} directive) whether or
4767 not assembly listings are generated. These two directives maintain an
4768 internal counter (which is zero initially). @code{.list} increments the
4769 counter, and @code{.nolist} decrements it. Assembly listings are
4770 generated whenever the counter is greater than zero.
4772 By default, listings are disabled. When you enable them (with the
4773 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4774 the initial value of the listing counter is one.
4777 @section @code{.long @var{expressions}}
4779 @cindex @code{long} directive
4780 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4783 @c no one seems to know what this is for or whether this description is
4784 @c what it really ought to do
4786 @section @code{.lsym @var{symbol}, @var{expression}}
4788 @cindex @code{lsym} directive
4789 @cindex symbol, not referenced in assembly
4790 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4791 the hash table, ensuring it cannot be referenced by name during the
4792 rest of the assembly. This sets the attributes of the symbol to be
4793 the same as the expression value:
4795 @var{other} = @var{descriptor} = 0
4796 @var{type} = @r{(section of @var{expression})}
4797 @var{value} = @var{expression}
4800 The new symbol is not flagged as external.
4804 @section @code{.macro}
4807 The commands @code{.macro} and @code{.endm} allow you to define macros that
4808 generate assembly output. For example, this definition specifies a macro
4809 @code{sum} that puts a sequence of numbers into memory:
4812 .macro sum from=0, to=5
4821 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4833 @item .macro @var{macname}
4834 @itemx .macro @var{macname} @var{macargs} @dots{}
4835 @cindex @code{macro} directive
4836 Begin the definition of a macro called @var{macname}. If your macro
4837 definition requires arguments, specify their names after the macro name,
4838 separated by commas or spaces. You can supply a default value for any
4839 macro argument by following the name with @samp{=@var{deflt}}. For
4840 example, these are all valid @code{.macro} statements:
4844 Begin the definition of a macro called @code{comm}, which takes no
4847 @item .macro plus1 p, p1
4848 @itemx .macro plus1 p p1
4849 Either statement begins the definition of a macro called @code{plus1},
4850 which takes two arguments; within the macro definition, write
4851 @samp{\p} or @samp{\p1} to evaluate the arguments.
4853 @item .macro reserve_str p1=0 p2
4854 Begin the definition of a macro called @code{reserve_str}, with two
4855 arguments. The first argument has a default value, but not the second.
4856 After the definition is complete, you can call the macro either as
4857 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4858 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4859 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4860 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4863 When you call a macro, you can specify the argument values either by
4864 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4865 @samp{sum to=17, from=9}.
4868 @cindex @code{endm} directive
4869 Mark the end of a macro definition.
4872 @cindex @code{exitm} directive
4873 Exit early from the current macro definition.
4875 @cindex number of macros executed
4876 @cindex macros, count executed
4878 @command{@value{AS}} maintains a counter of how many macros it has
4879 executed in this pseudo-variable; you can copy that number to your
4880 output with @samp{\@@}, but @emph{only within a macro definition}.
4882 @item LOCAL @var{name} [ , @dots{} ]
4883 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4884 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
4885 @xref{Altmacro,,@code{.altmacro}}.
4889 @section @code{.altmacro}
4890 Enable alternate macro mode, enabling:
4893 @item LOCAL @var{name} [ , @dots{} ]
4894 One additional directive, @code{LOCAL}, is available. It is used to
4895 generate a string replacement for each of the @var{name} arguments, and
4896 replace any instances of @var{name} in each macro expansion. The
4897 replacement string is unique in the assembly, and different for each
4898 separate macro expansion. @code{LOCAL} allows you to write macros that
4899 define symbols, without fear of conflict between separate macro expansions.
4901 @item String delimiters
4902 You can write strings delimited in these other ways besides
4903 @code{"@var{string}"}:
4906 @item '@var{string}'
4907 You can delimit strings with single-quote charaters.
4909 @item <@var{string}>
4910 You can delimit strings with matching angle brackets.
4913 @item single-character string escape
4914 To include any single character literally in a string (even if the
4915 character would otherwise have some special meaning), you can prefix the
4916 character with @samp{!} (an exclamation mark). For example, you can
4917 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4919 @item Expression results as strings
4920 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4921 and use the result as a string.
4925 @section @code{.noaltmacro}
4926 Disable alternate macro mode. @ref{Altmacro}
4929 @section @code{.nolist}
4931 @cindex @code{nolist} directive
4932 @cindex listing control, turning off
4933 Control (in conjunction with the @code{.list} directive) whether or
4934 not assembly listings are generated. These two directives maintain an
4935 internal counter (which is zero initially). @code{.list} increments the
4936 counter, and @code{.nolist} decrements it. Assembly listings are
4937 generated whenever the counter is greater than zero.
4940 @section @code{.octa @var{bignums}}
4942 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4943 @cindex @code{octa} directive
4944 @cindex integer, 16-byte
4945 @cindex sixteen byte integer
4946 This directive expects zero or more bignums, separated by commas. For each
4947 bignum, it emits a 16-byte integer.
4949 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4950 hence @emph{octa}-word for 16 bytes.
4953 @section @code{.org @var{new-lc} , @var{fill}}
4955 @cindex @code{org} directive
4956 @cindex location counter, advancing
4957 @cindex advancing location counter
4958 @cindex current address, advancing
4959 Advance the location counter of the current section to
4960 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4961 expression with the same section as the current subsection. That is,
4962 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4963 wrong section, the @code{.org} directive is ignored. To be compatible
4964 with former assemblers, if the section of @var{new-lc} is absolute,
4965 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4966 is the same as the current subsection.
4968 @code{.org} may only increase the location counter, or leave it
4969 unchanged; you cannot use @code{.org} to move the location counter
4972 @c double negative used below "not undefined" because this is a specific
4973 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4974 @c section. doc@cygnus.com 18feb91
4975 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4976 may not be undefined. If you really detest this restriction we eagerly await
4977 a chance to share your improved assembler.
4979 Beware that the origin is relative to the start of the section, not
4980 to the start of the subsection. This is compatible with other
4981 people's assemblers.
4983 When the location counter (of the current subsection) is advanced, the
4984 intervening bytes are filled with @var{fill} which should be an
4985 absolute expression. If the comma and @var{fill} are omitted,
4986 @var{fill} defaults to zero.
4989 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4991 @cindex padding the location counter given a power of two
4992 @cindex @code{p2align} directive
4993 Pad the location counter (in the current subsection) to a particular
4994 storage boundary. The first expression (which must be absolute) is the
4995 number of low-order zero bits the location counter must have after
4996 advancement. For example @samp{.p2align 3} advances the location
4997 counter until it a multiple of 8. If the location counter is already a
4998 multiple of 8, no change is needed.
5000 The second expression (also absolute) gives the fill value to be stored in the
5001 padding bytes. It (and the comma) may be omitted. If it is omitted, the
5002 padding bytes are normally zero. However, on some systems, if the section is
5003 marked as containing code and the fill value is omitted, the space is filled
5004 with no-op instructions.
5006 The third expression is also absolute, and is also optional. If it is present,
5007 it is the maximum number of bytes that should be skipped by this alignment
5008 directive. If doing the alignment would require skipping more bytes than the
5009 specified maximum, then the alignment is not done at all. You can omit the
5010 fill value (the second argument) entirely by simply using two commas after the
5011 required alignment; this can be useful if you want the alignment to be filled
5012 with no-op instructions when appropriate.
5014 @cindex @code{p2alignw} directive
5015 @cindex @code{p2alignl} directive
5016 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5017 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5018 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5019 fill pattern as a four byte longword value. For example, @code{.p2alignw
5020 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5021 filled in with the value 0x368d (the exact placement of the bytes depends upon
5022 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5027 @section @code{.previous}
5029 @cindex @code{previous} directive
5030 @cindex Section Stack
5031 This is one of the ELF section stack manipulation directives. The others are
5032 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5033 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5034 (@pxref{PopSection}).
5036 This directive swaps the current section (and subsection) with most recently
5037 referenced section (and subsection) prior to this one. Multiple
5038 @code{.previous} directives in a row will flip between two sections (and their
5041 In terms of the section stack, this directive swaps the current section with
5042 the top section on the section stack.
5047 @section @code{.popsection}
5049 @cindex @code{popsection} directive
5050 @cindex Section Stack
5051 This is one of the ELF section stack manipulation directives. The others are
5052 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5053 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5056 This directive replaces the current section (and subsection) with the top
5057 section (and subsection) on the section stack. This section is popped off the
5062 @section @code{.print @var{string}}
5064 @cindex @code{print} directive
5065 @command{@value{AS}} will print @var{string} on the standard output during
5066 assembly. You must put @var{string} in double quotes.
5070 @section @code{.protected @var{names}}
5072 @cindex @code{protected} directive
5074 This is one of the ELF visibility directives. The other two are
5075 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
5077 This directive overrides the named symbols default visibility (which is set by
5078 their binding: local, global or weak). The directive sets the visibility to
5079 @code{protected} which means that any references to the symbols from within the
5080 components that defines them must be resolved to the definition in that
5081 component, even if a definition in another component would normally preempt
5086 @section @code{.psize @var{lines} , @var{columns}}
5088 @cindex @code{psize} directive
5089 @cindex listing control: paper size
5090 @cindex paper size, for listings
5091 Use this directive to declare the number of lines---and, optionally, the
5092 number of columns---to use for each page, when generating listings.
5094 If you do not use @code{.psize}, listings use a default line-count
5095 of 60. You may omit the comma and @var{columns} specification; the
5096 default width is 200 columns.
5098 @command{@value{AS}} generates formfeeds whenever the specified number of
5099 lines is exceeded (or whenever you explicitly request one, using
5102 If you specify @var{lines} as @code{0}, no formfeeds are generated save
5103 those explicitly specified with @code{.eject}.
5106 @section @code{.purgem @var{name}}
5108 @cindex @code{purgem} directive
5109 Undefine the macro @var{name}, so that later uses of the string will not be
5110 expanded. @xref{Macro}.
5114 @section @code{.pushsection @var{name} , @var{subsection}}
5116 @cindex @code{pushsection} directive
5117 @cindex Section Stack
5118 This is one of the ELF section stack manipulation directives. The others are
5119 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5120 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5123 This directive pushes the current section (and subsection) onto the
5124 top of the section stack, and then replaces the current section and
5125 subsection with @code{name} and @code{subsection}.
5129 @section @code{.quad @var{bignums}}
5131 @cindex @code{quad} directive
5132 @code{.quad} expects zero or more bignums, separated by commas. For
5133 each bignum, it emits
5135 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
5136 warning message; and just takes the lowest order 8 bytes of the bignum.
5137 @cindex eight-byte integer
5138 @cindex integer, 8-byte
5140 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
5141 hence @emph{quad}-word for 8 bytes.
5144 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
5145 warning message; and just takes the lowest order 16 bytes of the bignum.
5146 @cindex sixteen-byte integer
5147 @cindex integer, 16-byte
5151 @section @code{.rept @var{count}}
5153 @cindex @code{rept} directive
5154 Repeat the sequence of lines between the @code{.rept} directive and the next
5155 @code{.endr} directive @var{count} times.
5157 For example, assembling
5165 is equivalent to assembling
5174 @section @code{.sbttl "@var{subheading}"}
5176 @cindex @code{sbttl} directive
5177 @cindex subtitles for listings
5178 @cindex listing control: subtitle
5179 Use @var{subheading} as the title (third line, immediately after the
5180 title line) when generating assembly listings.
5182 This directive affects subsequent pages, as well as the current page if
5183 it appears within ten lines of the top of a page.
5187 @section @code{.scl @var{class}}
5189 @cindex @code{scl} directive
5190 @cindex symbol storage class (COFF)
5191 @cindex COFF symbol storage class
5192 Set the storage-class value for a symbol. This directive may only be
5193 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
5194 whether a symbol is static or external, or it may record further
5195 symbolic debugging information.
5198 The @samp{.scl} directive is primarily associated with COFF output; when
5199 configured to generate @code{b.out} output format, @command{@value{AS}}
5200 accepts this directive but ignores it.
5206 @section @code{.section @var{name}}
5208 @cindex named section
5209 Use the @code{.section} directive to assemble the following code into a section
5212 This directive is only supported for targets that actually support arbitrarily
5213 named sections; on @code{a.out} targets, for example, it is not accepted, even
5214 with a standard @code{a.out} section name.
5218 @c only print the extra heading if both COFF and ELF are set
5219 @subheading COFF Version
5222 @cindex @code{section} directive (COFF version)
5223 For COFF targets, the @code{.section} directive is used in one of the following
5227 .section @var{name}[, "@var{flags}"]
5228 .section @var{name}[, @var{subsegment}]
5231 If the optional argument is quoted, it is taken as flags to use for the
5232 section. Each flag is a single character. The following flags are recognized:
5235 bss section (uninitialized data)
5237 section is not loaded
5247 shared section (meaningful for PE targets)
5249 ignored. (For compatibility with the ELF version)
5252 If no flags are specified, the default flags depend upon the section name. If
5253 the section name is not recognized, the default will be for the section to be
5254 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
5255 from the section, rather than adding them, so if they are used on their own it
5256 will be as if no flags had been specified at all.
5258 If the optional argument to the @code{.section} directive is not quoted, it is
5259 taken as a subsegment number (@pxref{Sub-Sections}).
5264 @c only print the extra heading if both COFF and ELF are set
5265 @subheading ELF Version
5268 @cindex Section Stack
5269 This is one of the ELF section stack manipulation directives. The others are
5270 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5271 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5272 @code{.previous} (@pxref{Previous}).
5274 @cindex @code{section} directive (ELF version)
5275 For ELF targets, the @code{.section} directive is used like this:
5278 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]
5281 The optional @var{flags} argument is a quoted string which may contain any
5282 combination of the following characters:
5285 section is allocatable
5289 section is executable
5291 section is mergeable
5293 section contains zero terminated strings
5295 section is a member of a section group
5297 section is used for thread-local-storage
5300 The optional @var{type} argument may contain one of the following constants:
5303 section contains data
5305 section does not contain data (i.e., section only occupies space)
5307 section contains data which is used by things other than the program
5309 section contains an array of pointers to init functions
5311 section contains an array of pointers to finish functions
5312 @item @@preinit_array
5313 section contains an array of pointers to pre-init functions
5316 Many targets only support the first three section types.
5318 Note on targets where the @code{@@} character is the start of a comment (eg
5319 ARM) then another character is used instead. For example the ARM port uses the
5322 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
5323 be specified as well as an extra argument - @var{entsize} - like this:
5326 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
5329 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
5330 constants, each @var{entsize} octets long. Sections with both @code{M} and
5331 @code{S} must contain zero terminated strings where each character is
5332 @var{entsize} bytes long. The linker may remove duplicates within sections with
5333 the same name, same entity size and same flags. @var{entsize} must be an
5334 absolute expression.
5336 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
5337 be present along with an additional field like this:
5340 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
5343 The @var{GroupName} field specifies the name of the section group to which this
5344 particular section belongs. The optional linkage field can contain:
5347 indicates that only one copy of this section should be retained
5352 Note - if both the @var{M} and @var{G} flags are present then the fields for
5353 the Merge flag should come first, like this:
5356 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
5359 If no flags are specified, the default flags depend upon the section name. If
5360 the section name is not recognized, the default will be for the section to have
5361 none of the above flags: it will not be allocated in memory, nor writable, nor
5362 executable. The section will contain data.
5364 For ELF targets, the assembler supports another type of @code{.section}
5365 directive for compatibility with the Solaris assembler:
5368 .section "@var{name}"[, @var{flags}...]
5371 Note that the section name is quoted. There may be a sequence of comma
5375 section is allocatable
5379 section is executable
5381 section is used for thread local storage
5384 This directive replaces the current section and subsection. See the
5385 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
5386 some examples of how this directive and the other section stack directives
5392 @section @code{.set @var{symbol}, @var{expression}}
5394 @cindex @code{set} directive
5395 @cindex symbol value, setting
5396 Set the value of @var{symbol} to @var{expression}. This
5397 changes @var{symbol}'s value and type to conform to
5398 @var{expression}. If @var{symbol} was flagged as external, it remains
5399 flagged (@pxref{Symbol Attributes}).
5401 You may @code{.set} a symbol many times in the same assembly.
5403 If you @code{.set} a global symbol, the value stored in the object
5404 file is the last value stored into it.
5407 The syntax for @code{set} on the HPPA is
5408 @samp{@var{symbol} .set @var{expression}}.
5412 @section @code{.short @var{expressions}}
5414 @cindex @code{short} directive
5416 @code{.short} is normally the same as @samp{.word}.
5417 @xref{Word,,@code{.word}}.
5419 In some configurations, however, @code{.short} and @code{.word} generate
5420 numbers of different lengths; @pxref{Machine Dependencies}.
5424 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5427 This expects zero or more @var{expressions}, and emits
5428 a 16 bit number for each.
5433 @section @code{.single @var{flonums}}
5435 @cindex @code{single} directive
5436 @cindex floating point numbers (single)
5437 This directive assembles zero or more flonums, separated by commas. It
5438 has the same effect as @code{.float}.
5440 The exact kind of floating point numbers emitted depends on how
5441 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5445 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5446 numbers in @sc{ieee} format.
5452 @section @code{.size}
5454 This directive is used to set the size associated with a symbol.
5458 @c only print the extra heading if both COFF and ELF are set
5459 @subheading COFF Version
5462 @cindex @code{size} directive (COFF version)
5463 For COFF targets, the @code{.size} directive is only permitted inside
5464 @code{.def}/@code{.endef} pairs. It is used like this:
5467 .size @var{expression}
5471 @samp{.size} is only meaningful when generating COFF format output; when
5472 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5479 @c only print the extra heading if both COFF and ELF are set
5480 @subheading ELF Version
5483 @cindex @code{size} directive (ELF version)
5484 For ELF targets, the @code{.size} directive is used like this:
5487 .size @var{name} , @var{expression}
5490 This directive sets the size associated with a symbol @var{name}.
5491 The size in bytes is computed from @var{expression} which can make use of label
5492 arithmetic. This directive is typically used to set the size of function
5498 @section @code{.sleb128 @var{expressions}}
5500 @cindex @code{sleb128} directive
5501 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5502 compact, variable length representation of numbers used by the DWARF
5503 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5505 @ifclear no-space-dir
5507 @section @code{.skip @var{size} , @var{fill}}
5509 @cindex @code{skip} directive
5510 @cindex filling memory
5511 This directive emits @var{size} bytes, each of value @var{fill}. Both
5512 @var{size} and @var{fill} are absolute expressions. If the comma and
5513 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5517 @section @code{.space @var{size} , @var{fill}}
5519 @cindex @code{space} directive
5520 @cindex filling memory
5521 This directive emits @var{size} bytes, each of value @var{fill}. Both
5522 @var{size} and @var{fill} are absolute expressions. If the comma
5523 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5528 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5529 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5530 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5531 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5540 @section @code{.space}
5541 @cindex @code{space} directive
5543 On the AMD 29K, this directive is ignored; it is accepted for
5544 compatibility with other AMD 29K assemblers.
5547 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5548 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5554 @section @code{.stabd, .stabn, .stabs}
5556 @cindex symbolic debuggers, information for
5557 @cindex @code{stab@var{x}} directives
5558 There are three directives that begin @samp{.stab}.
5559 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5560 The symbols are not entered in the @command{@value{AS}} hash table: they
5561 cannot be referenced elsewhere in the source file.
5562 Up to five fields are required:
5566 This is the symbol's name. It may contain any character except
5567 @samp{\000}, so is more general than ordinary symbol names. Some
5568 debuggers used to code arbitrarily complex structures into symbol names
5572 An absolute expression. The symbol's type is set to the low 8 bits of
5573 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5574 and debuggers choke on silly bit patterns.
5577 An absolute expression. The symbol's ``other'' attribute is set to the
5578 low 8 bits of this expression.
5581 An absolute expression. The symbol's descriptor is set to the low 16
5582 bits of this expression.
5585 An absolute expression which becomes the symbol's value.
5588 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5589 or @code{.stabs} statement, the symbol has probably already been created;
5590 you get a half-formed symbol in your object file. This is
5591 compatible with earlier assemblers!
5594 @cindex @code{stabd} directive
5595 @item .stabd @var{type} , @var{other} , @var{desc}
5597 The ``name'' of the symbol generated is not even an empty string.
5598 It is a null pointer, for compatibility. Older assemblers used a
5599 null pointer so they didn't waste space in object files with empty
5602 The symbol's value is set to the location counter,
5603 relocatably. When your program is linked, the value of this symbol
5604 is the address of the location counter when the @code{.stabd} was
5607 @cindex @code{stabn} directive
5608 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5609 The name of the symbol is set to the empty string @code{""}.
5611 @cindex @code{stabs} directive
5612 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5613 All five fields are specified.
5619 @section @code{.string} "@var{str}"
5621 @cindex string, copying to object file
5622 @cindex @code{string} directive
5624 Copy the characters in @var{str} to the object file. You may specify more than
5625 one string to copy, separated by commas. Unless otherwise specified for a
5626 particular machine, the assembler marks the end of each string with a 0 byte.
5627 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5630 @section @code{.struct @var{expression}}
5632 @cindex @code{struct} directive
5633 Switch to the absolute section, and set the section offset to @var{expression},
5634 which must be an absolute expression. You might use this as follows:
5643 This would define the symbol @code{field1} to have the value 0, the symbol
5644 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5645 value 8. Assembly would be left in the absolute section, and you would need to
5646 use a @code{.section} directive of some sort to change to some other section
5647 before further assembly.
5651 @section @code{.subsection @var{name}}
5653 @cindex @code{subsection} directive
5654 @cindex Section Stack
5655 This is one of the ELF section stack manipulation directives. The others are
5656 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5657 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5660 This directive replaces the current subsection with @code{name}. The current
5661 section is not changed. The replaced subsection is put onto the section stack
5662 in place of the then current top of stack subsection.
5667 @section @code{.symver}
5668 @cindex @code{symver} directive
5669 @cindex symbol versioning
5670 @cindex versions of symbols
5671 Use the @code{.symver} directive to bind symbols to specific version nodes
5672 within a source file. This is only supported on ELF platforms, and is
5673 typically used when assembling files to be linked into a shared library.
5674 There are cases where it may make sense to use this in objects to be bound
5675 into an application itself so as to override a versioned symbol from a
5678 For ELF targets, the @code{.symver} directive can be used like this:
5680 .symver @var{name}, @var{name2@@nodename}
5682 If the symbol @var{name} is defined within the file
5683 being assembled, the @code{.symver} directive effectively creates a symbol
5684 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5685 just don't try and create a regular alias is that the @var{@@} character isn't
5686 permitted in symbol names. The @var{name2} part of the name is the actual name
5687 of the symbol by which it will be externally referenced. The name @var{name}
5688 itself is merely a name of convenience that is used so that it is possible to
5689 have definitions for multiple versions of a function within a single source
5690 file, and so that the compiler can unambiguously know which version of a
5691 function is being mentioned. The @var{nodename} portion of the alias should be
5692 the name of a node specified in the version script supplied to the linker when
5693 building a shared library. If you are attempting to override a versioned
5694 symbol from a shared library, then @var{nodename} should correspond to the
5695 nodename of the symbol you are trying to override.
5697 If the symbol @var{name} is not defined within the file being assembled, all
5698 references to @var{name} will be changed to @var{name2@@nodename}. If no
5699 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5702 Another usage of the @code{.symver} directive is:
5704 .symver @var{name}, @var{name2@@@@nodename}
5706 In this case, the symbol @var{name} must exist and be defined within
5707 the file being assembled. It is similar to @var{name2@@nodename}. The
5708 difference is @var{name2@@@@nodename} will also be used to resolve
5709 references to @var{name2} by the linker.
5711 The third usage of the @code{.symver} directive is:
5713 .symver @var{name}, @var{name2@@@@@@nodename}
5715 When @var{name} is not defined within the
5716 file being assembled, it is treated as @var{name2@@nodename}. When
5717 @var{name} is defined within the file being assembled, the symbol
5718 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5723 @section @code{.tag @var{structname}}
5725 @cindex COFF structure debugging
5726 @cindex structure debugging, COFF
5727 @cindex @code{tag} directive
5728 This directive is generated by compilers to include auxiliary debugging
5729 information in the symbol table. It is only permitted inside
5730 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5731 definitions in the symbol table with instances of those structures.
5734 @samp{.tag} is only used when generating COFF format output; when
5735 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5741 @section @code{.text @var{subsection}}
5743 @cindex @code{text} directive
5744 Tells @command{@value{AS}} to assemble the following statements onto the end of
5745 the text subsection numbered @var{subsection}, which is an absolute
5746 expression. If @var{subsection} is omitted, subsection number zero
5750 @section @code{.title "@var{heading}"}
5752 @cindex @code{title} directive
5753 @cindex listing control: title line
5754 Use @var{heading} as the title (second line, immediately after the
5755 source file name and pagenumber) when generating assembly listings.
5757 This directive affects subsequent pages, as well as the current page if
5758 it appears within ten lines of the top of a page.
5762 @section @code{.type}
5764 This directive is used to set the type of a symbol.
5768 @c only print the extra heading if both COFF and ELF are set
5769 @subheading COFF Version
5772 @cindex COFF symbol type
5773 @cindex symbol type, COFF
5774 @cindex @code{type} directive (COFF version)
5775 For COFF targets, this directive is permitted only within
5776 @code{.def}/@code{.endef} pairs. It is used like this:
5782 This records the integer @var{int} as the type attribute of a symbol table
5786 @samp{.type} is associated only with COFF format output; when
5787 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5788 directive but ignores it.
5794 @c only print the extra heading if both COFF and ELF are set
5795 @subheading ELF Version
5798 @cindex ELF symbol type
5799 @cindex symbol type, ELF
5800 @cindex @code{type} directive (ELF version)
5801 For ELF targets, the @code{.type} directive is used like this:
5804 .type @var{name} , @var{type description}
5807 This sets the type of symbol @var{name} to be either a
5808 function symbol or an object symbol. There are five different syntaxes
5809 supported for the @var{type description} field, in order to provide
5810 compatibility with various other assemblers. The syntaxes supported are:
5813 .type <name>,#function
5814 .type <name>,#object
5816 .type <name>,@@function
5817 .type <name>,@@object
5819 .type <name>,%function
5820 .type <name>,%object
5822 .type <name>,"function"
5823 .type <name>,"object"
5825 .type <name> STT_FUNCTION
5826 .type <name> STT_OBJECT
5832 @section @code{.uleb128 @var{expressions}}
5834 @cindex @code{uleb128} directive
5835 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5836 compact, variable length representation of numbers used by the DWARF
5837 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5841 @section @code{.val @var{addr}}
5843 @cindex @code{val} directive
5844 @cindex COFF value attribute
5845 @cindex value attribute, COFF
5846 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5847 records the address @var{addr} as the value attribute of a symbol table
5851 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5852 configured for @code{b.out}, it accepts this directive but ignores it.
5858 @section @code{.version "@var{string}"}
5860 @cindex @code{version} directive
5861 This directive creates a @code{.note} section and places into it an ELF
5862 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5867 @section @code{.vtable_entry @var{table}, @var{offset}}
5869 @cindex @code{vtable_entry} directive
5870 This directive finds or creates a symbol @code{table} and creates a
5871 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5874 @section @code{.vtable_inherit @var{child}, @var{parent}}
5876 @cindex @code{vtable_inherit} directive
5877 This directive finds the symbol @code{child} and finds or creates the symbol
5878 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5879 parent whose addend is the value of the child symbol. As a special case the
5880 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5884 @section @code{.warning "@var{string}"}
5885 @cindex warning directive
5886 Similar to the directive @code{.error}
5887 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
5890 @section @code{.weak @var{names}}
5892 @cindex @code{weak} directive
5893 This directive sets the weak attribute on the comma separated list of symbol
5894 @code{names}. If the symbols do not already exist, they will be created.
5896 On COFF targets other than PE, weak symbols are a GNU extension. This
5897 directive sets the weak attribute on the comma separated list of symbol
5898 @code{names}. If the symbols do not already exist, they will be created.
5900 On the PE target, weak symbols are supported natively as weak aliases.
5901 When a weak symbol is created that is not an alias, GAS creates an
5902 alternate symbol to hold the default value.
5905 @section @code{.word @var{expressions}}
5907 @cindex @code{word} directive
5908 This directive expects zero or more @var{expressions}, of any section,
5909 separated by commas.
5912 For each expression, @command{@value{AS}} emits a 32-bit number.
5915 For each expression, @command{@value{AS}} emits a 16-bit number.
5920 The size of the number emitted, and its byte order,
5921 depend on what target computer the assembly is for.
5924 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5925 @c happen---32-bit addressability, period; no long/short jumps.
5926 @ifset DIFF-TBL-KLUGE
5927 @cindex difference tables altered
5928 @cindex altered difference tables
5930 @emph{Warning: Special Treatment to support Compilers}
5934 Machines with a 32-bit address space, but that do less than 32-bit
5935 addressing, require the following special treatment. If the machine of
5936 interest to you does 32-bit addressing (or doesn't require it;
5937 @pxref{Machine Dependencies}), you can ignore this issue.
5940 In order to assemble compiler output into something that works,
5941 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5942 Directives of the form @samp{.word sym1-sym2} are often emitted by
5943 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5944 directive of the form @samp{.word sym1-sym2}, and the difference between
5945 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5946 creates a @dfn{secondary jump table}, immediately before the next label.
5947 This secondary jump table is preceded by a short-jump to the
5948 first byte after the secondary table. This short-jump prevents the flow
5949 of control from accidentally falling into the new table. Inside the
5950 table is a long-jump to @code{sym2}. The original @samp{.word}
5951 contains @code{sym1} minus the address of the long-jump to
5954 If there were several occurrences of @samp{.word sym1-sym2} before the
5955 secondary jump table, all of them are adjusted. If there was a
5956 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5957 long-jump to @code{sym4} is included in the secondary jump table,
5958 and the @code{.word} directives are adjusted to contain @code{sym3}
5959 minus the address of the long-jump to @code{sym4}; and so on, for as many
5960 entries in the original jump table as necessary.
5963 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5964 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5965 assembly language programmers.
5968 @c end DIFF-TBL-KLUGE
5971 @section Deprecated Directives
5973 @cindex deprecated directives
5974 @cindex obsolescent directives
5975 One day these directives won't work.
5976 They are included for compatibility with older assemblers.
5983 @node Machine Dependencies
5984 @chapter Machine Dependent Features
5986 @cindex machine dependencies
5987 The machine instruction sets are (almost by definition) different on
5988 each machine where @command{@value{AS}} runs. Floating point representations
5989 vary as well, and @command{@value{AS}} often supports a few additional
5990 directives or command-line options for compatibility with other
5991 assemblers on a particular platform. Finally, some versions of
5992 @command{@value{AS}} support special pseudo-instructions for branch
5995 This chapter discusses most of these differences, though it does not
5996 include details on any machine's instruction set. For details on that
5997 subject, see the hardware manufacturer's manual.
6001 * AMD29K-Dependent:: AMD 29K Dependent Features
6004 * Alpha-Dependent:: Alpha Dependent Features
6007 * ARC-Dependent:: ARC Dependent Features
6010 * ARM-Dependent:: ARM Dependent Features
6013 * CRIS-Dependent:: CRIS Dependent Features
6016 * D10V-Dependent:: D10V Dependent Features
6019 * D30V-Dependent:: D30V Dependent Features
6022 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6025 * H8/500-Dependent:: Renesas H8/500 Dependent Features
6028 * HPPA-Dependent:: HPPA Dependent Features
6031 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
6034 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
6037 * i860-Dependent:: Intel 80860 Dependent Features
6040 * i960-Dependent:: Intel 80960 Dependent Features
6043 * IP2K-Dependent:: IP2K Dependent Features
6046 * M32R-Dependent:: M32R Dependent Features
6049 * M68K-Dependent:: M680x0 Dependent Features
6052 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
6055 * M88K-Dependent:: M880x0 Dependent Features
6058 * MIPS-Dependent:: MIPS Dependent Features
6061 * MMIX-Dependent:: MMIX Dependent Features
6064 * MSP430-Dependent:: MSP430 Dependent Features
6067 * SH-Dependent:: Renesas / SuperH SH Dependent Features
6068 * SH64-Dependent:: SuperH SH64 Dependent Features
6071 * PDP-11-Dependent:: PDP-11 Dependent Features
6074 * PJ-Dependent:: picoJava Dependent Features
6077 * PPC-Dependent:: PowerPC Dependent Features
6080 * Sparc-Dependent:: SPARC Dependent Features
6083 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
6086 * V850-Dependent:: V850 Dependent Features
6089 * Xtensa-Dependent:: Xtensa Dependent Features
6092 * Z8000-Dependent:: Z8000 Dependent Features
6095 * Vax-Dependent:: VAX Dependent Features
6102 @c The following major nodes are *sections* in the GENERIC version, *chapters*
6103 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
6104 @c peculiarity: to preserve cross-references, there must be a node called
6105 @c "Machine Dependencies". Hence the conditional nodenames in each
6106 @c major node below. Node defaulting in makeinfo requires adjacency of
6107 @c node and sectioning commands; hence the repetition of @chapter BLAH
6108 @c in both conditional blocks.
6111 @include c-a29k.texi
6115 @include c-alpha.texi
6127 @include c-cris.texi
6132 @node Machine Dependencies
6133 @chapter Machine Dependent Features
6135 The machine instruction sets are different on each Renesas chip family,
6136 and there are also some syntax differences among the families. This
6137 chapter describes the specific @command{@value{AS}} features for each
6141 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6142 * H8/500-Dependent:: Renesas H8/500 Dependent Features
6143 * SH-Dependent:: Renesas SH Dependent Features
6150 @include c-d10v.texi
6154 @include c-d30v.texi
6158 @include c-h8300.texi
6162 @include c-h8500.texi
6166 @include c-hppa.texi
6170 @include c-i370.texi
6174 @include c-i386.texi
6178 @include c-i860.texi
6182 @include c-i960.texi
6186 @include c-ia64.texi
6190 @include c-ip2k.texi
6194 @include c-m32r.texi
6198 @include c-m68k.texi
6202 @include c-m68hc11.texi
6206 @include c-m88k.texi
6210 @include c-mips.texi
6214 @include c-mmix.texi
6218 @include c-msp430.texi
6222 @include c-ns32k.texi
6226 @include c-pdp11.texi
6239 @include c-sh64.texi
6243 @include c-sparc.texi
6247 @include c-tic54x.texi
6259 @include c-v850.texi
6263 @include c-xtensa.texi
6267 @c reverse effect of @down at top of generic Machine-Dep chapter
6271 @node Reporting Bugs
6272 @chapter Reporting Bugs
6273 @cindex bugs in assembler
6274 @cindex reporting bugs in assembler
6276 Your bug reports play an essential role in making @command{@value{AS}} reliable.
6278 Reporting a bug may help you by bringing a solution to your problem, or it may
6279 not. But in any case the principal function of a bug report is to help the
6280 entire community by making the next version of @command{@value{AS}} work better.
6281 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
6283 In order for a bug report to serve its purpose, you must include the
6284 information that enables us to fix the bug.
6287 * Bug Criteria:: Have you found a bug?
6288 * Bug Reporting:: How to report bugs
6292 @section Have You Found a Bug?
6293 @cindex bug criteria
6295 If you are not sure whether you have found a bug, here are some guidelines:
6298 @cindex fatal signal
6299 @cindex assembler crash
6300 @cindex crash of assembler
6302 If the assembler gets a fatal signal, for any input whatever, that is a
6303 @command{@value{AS}} bug. Reliable assemblers never crash.
6305 @cindex error on valid input
6307 If @command{@value{AS}} produces an error message for valid input, that is a bug.
6309 @cindex invalid input
6311 If @command{@value{AS}} does not produce an error message for invalid input, that
6312 is a bug. However, you should note that your idea of ``invalid input'' might
6313 be our idea of ``an extension'' or ``support for traditional practice''.
6316 If you are an experienced user of assemblers, your suggestions for improvement
6317 of @command{@value{AS}} are welcome in any case.
6321 @section How to Report Bugs
6323 @cindex assembler bugs, reporting
6325 A number of companies and individuals offer support for @sc{gnu} products. If
6326 you obtained @command{@value{AS}} from a support organization, we recommend you
6327 contact that organization first.
6329 You can find contact information for many support companies and
6330 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
6333 In any event, we also recommend that you send bug reports for @command{@value{AS}}
6334 to @samp{bug-binutils@@gnu.org}.
6336 The fundamental principle of reporting bugs usefully is this:
6337 @strong{report all the facts}. If you are not sure whether to state a
6338 fact or leave it out, state it!
6340 Often people omit facts because they think they know what causes the problem
6341 and assume that some details do not matter. Thus, you might assume that the
6342 name of a symbol you use in an example does not matter. Well, probably it does
6343 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
6344 happens to fetch from the location where that name is stored in memory;
6345 perhaps, if the name were different, the contents of that location would fool
6346 the assembler into doing the right thing despite the bug. Play it safe and
6347 give a specific, complete example. That is the easiest thing for you to do,
6348 and the most helpful.
6350 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
6351 it is new to us. Therefore, always write your bug reports on the assumption
6352 that the bug has not been reported previously.
6354 Sometimes people give a few sketchy facts and ask, ``Does this ring a
6355 bell?'' This cannot help us fix a bug, so it is basically useless. We
6356 respond by asking for enough details to enable us to investigate.
6357 You might as well expedite matters by sending them to begin with.
6359 To enable us to fix the bug, you should include all these things:
6363 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
6364 it with the @samp{--version} argument.
6366 Without this, we will not know whether there is any point in looking for
6367 the bug in the current version of @command{@value{AS}}.
6370 Any patches you may have applied to the @command{@value{AS}} source.
6373 The type of machine you are using, and the operating system name and
6377 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
6381 The command arguments you gave the assembler to assemble your example and
6382 observe the bug. To guarantee you will not omit something important, list them
6383 all. A copy of the Makefile (or the output from make) is sufficient.
6385 If we were to try to guess the arguments, we would probably guess wrong
6386 and then we might not encounter the bug.
6389 A complete input file that will reproduce the bug. If the bug is observed when
6390 the assembler is invoked via a compiler, send the assembler source, not the
6391 high level language source. Most compilers will produce the assembler source
6392 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
6393 the options @samp{-v --save-temps}; this will save the assembler source in a
6394 file with an extension of @file{.s}, and also show you exactly how
6395 @command{@value{AS}} is being run.
6398 A description of what behavior you observe that you believe is
6399 incorrect. For example, ``It gets a fatal signal.''
6401 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
6402 will certainly notice it. But if the bug is incorrect output, we might not
6403 notice unless it is glaringly wrong. You might as well not give us a chance to
6406 Even if the problem you experience is a fatal signal, you should still say so
6407 explicitly. Suppose something strange is going on, such as, your copy of
6408 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
6409 library on your system. (This has happened!) Your copy might crash and ours
6410 would not. If you told us to expect a crash, then when ours fails to crash, we
6411 would know that the bug was not happening for us. If you had not told us to
6412 expect a crash, then we would not be able to draw any conclusion from our
6416 If you wish to suggest changes to the @command{@value{AS}} source, send us context
6417 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
6418 option. Always send diffs from the old file to the new file. If you even
6419 discuss something in the @command{@value{AS}} source, refer to it by context, not
6422 The line numbers in our development sources will not match those in your
6423 sources. Your line numbers would convey no useful information to us.
6426 Here are some things that are not necessary:
6430 A description of the envelope of the bug.
6432 Often people who encounter a bug spend a lot of time investigating
6433 which changes to the input file will make the bug go away and which
6434 changes will not affect it.
6436 This is often time consuming and not very useful, because the way we
6437 will find the bug is by running a single example under the debugger
6438 with breakpoints, not by pure deduction from a series of examples.
6439 We recommend that you save your time for something else.
6441 Of course, if you can find a simpler example to report @emph{instead}
6442 of the original one, that is a convenience for us. Errors in the
6443 output will be easier to spot, running under the debugger will take
6444 less time, and so on.
6446 However, simplification is not vital; if you do not want to do this,
6447 report the bug anyway and send us the entire test case you used.
6450 A patch for the bug.
6452 A patch for the bug does help us if it is a good one. But do not omit
6453 the necessary information, such as the test case, on the assumption that
6454 a patch is all we need. We might see problems with your patch and decide
6455 to fix the problem another way, or we might not understand it at all.
6457 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6458 construct an example that will make the program follow a certain path through
6459 the code. If you do not send us the example, we will not be able to construct
6460 one, so we will not be able to verify that the bug is fixed.
6462 And if we cannot understand what bug you are trying to fix, or why your
6463 patch should be an improvement, we will not install it. A test case will
6464 help us to understand.
6467 A guess about what the bug is or what it depends on.
6469 Such guesses are usually wrong. Even we cannot guess right about such
6470 things without first using the debugger to find the facts.
6473 @node Acknowledgements
6474 @chapter Acknowledgements
6476 If you have contributed to GAS and your name isn't listed here,
6477 it is not meant as a slight. We just don't know about it. Send mail to the
6478 maintainer, and we'll correct the situation. Currently
6480 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6482 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6485 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6486 information and the 68k series machines, most of the preprocessing pass, and
6487 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6489 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6490 many bug fixes, including merging support for several processors, breaking GAS
6491 up to handle multiple object file format back ends (including heavy rewrite,
6492 testing, an integration of the coff and b.out back ends), adding configuration
6493 including heavy testing and verification of cross assemblers and file splits
6494 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6495 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6496 port (including considerable amounts of reverse engineering), a SPARC opcode
6497 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6498 assertions and made them work, much other reorganization, cleanup, and lint.
6500 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6501 in format-specific I/O modules.
6503 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6504 has done much work with it since.
6506 The Intel 80386 machine description was written by Eliot Dresselhaus.
6508 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6510 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6511 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6513 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6514 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6515 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6516 support a.out format.
6518 Support for the Zilog Z8k and Renesas H8/300 and H8/500 processors (tc-z8k,
6519 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6520 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6521 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6524 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6525 simplified the configuration of which versions accept which directives. He
6526 updated the 68k machine description so that Motorola's opcodes always produced
6527 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
6528 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6529 cross-compilation support, and one bug in relaxation that took a week and
6530 required the proverbial one-bit fix.
6532 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6533 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6534 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6535 PowerPC assembler, and made a few other minor patches.
6537 Steve Chamberlain made GAS able to generate listings.
6539 Hewlett-Packard contributed support for the HP9000/300.
6541 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6542 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6543 formats). This work was supported by both the Center for Software Science at
6544 the University of Utah and Cygnus Support.
6546 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6547 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6548 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6549 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6550 and some initial 64-bit support).
6552 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
6554 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6555 support for openVMS/Alpha.
6557 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6560 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
6561 Inc. added support for Xtensa processors.
6563 Several engineers at Cygnus Support have also provided many small bug fixes and
6564 configuration enhancements.
6566 Many others have contributed large or small bugfixes and enhancements. If
6567 you have contributed significant work and are not mentioned on this list, and
6568 want to be, let us know. Some of the history has been lost; we are not
6569 intentionally leaving anyone out.
projects / deliverable / binutils-gdb.git / blob