1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
3 @c 2001, 2002, 2003, 2004, 2005
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{-mtune=itanium1}|@b{-mtune=itanium2}]
319 [@b{-munwind-check=warning}|@b{-munwind-check=error}]
320 [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}]
321 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
325 @emph{Target IP2K options:}
326 [@b{-mip2022}|@b{-mip2022ext}]
330 @emph{Target M32R options:}
331 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
336 @emph{Target M680X0 options:}
337 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
341 @emph{Target M68HC11 options:}
342 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}]
343 [@b{-mshort}|@b{-mlong}]
344 [@b{-mshort-double}|@b{-mlong-double}]
345 [@b{--force-long-branchs}] [@b{--short-branchs}]
346 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
347 [@b{--print-opcodes}] [@b{--generate-example}]
351 @emph{Target MCORE options:}
352 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
353 [@b{-mcpu=[210|340]}]
357 @emph{Target MIPS options:}
358 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
359 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
360 [@b{-non_shared}] [@b{-xgot}]
361 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
362 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
363 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
364 [@b{-mips64}] [@b{-mips64r2}]
365 [@b{-construct-floats}] [@b{-no-construct-floats}]
366 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
367 [@b{-mfix7000}] [@b{-mno-fix7000}]
368 [@b{-mips16}] [@b{-no-mips16}]
369 [@b{-mips3d}] [@b{-no-mips3d}]
370 [@b{-mdmx}] [@b{-no-mdmx}]
371 [@b{-mdebug}] [@b{-no-mdebug}]
372 [@b{-mpdr}] [@b{-mno-pdr}]
376 @emph{Target MMIX options:}
377 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
378 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
379 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
380 [@b{--linker-allocated-gregs}]
384 @emph{Target PDP11 options:}
385 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
386 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
387 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
391 @emph{Target picoJava options:}
396 @emph{Target PowerPC options:}
397 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
398 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
399 @b{-mbooke32}|@b{-mbooke64}]
400 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
401 [@b{-mregnames}|@b{-mno-regnames}]
402 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
403 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
404 [@b{-msolaris}|@b{-mno-solaris}]
408 @emph{Target SPARC options:}
409 @c The order here is important. See c-sparc.texi.
410 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
411 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
412 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
417 @emph{Target TIC54X options:}
418 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
419 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
422 @c Z8000 has no machine-dependent assembler options
426 @emph{Target Xtensa options:}
427 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
428 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
429 [@b{--[no-]transform}]
430 [@b{--rename-section} @var{oldname}=@var{newname}]
439 Turn on listings, in any of a variety of ways:
443 omit false conditionals
446 omit debugging directives
449 include high-level source
455 include macro expansions
458 omit forms processing
464 set the name of the listing file
467 You may combine these options; for example, use @samp{-aln} for assembly
468 listing without forms processing. The @samp{=file} option, if used, must be
469 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
472 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
475 Ignored. This option is accepted for script compatibility with calls to
478 @item --defsym @var{sym}=@var{value}
479 Define the symbol @var{sym} to be @var{value} before assembling the input file.
480 @var{value} must be an integer constant. As in C, a leading @samp{0x}
481 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
484 ``fast''---skip whitespace and comment preprocessing (assume source is
489 Generate debugging information for each assembler source line using whichever
490 debug format is preferred by the target. This currently means either STABS,
494 Generate stabs debugging information for each assembler line. This
495 may help debugging assembler code, if the debugger can handle it.
498 Generate stabs debugging information for each assembler line, with GNU
499 extensions that probably only gdb can handle, and that could make other
500 debuggers crash or refuse to read your program. This
501 may help debugging assembler code. Currently the only GNU extension is
502 the location of the current working directory at assembling time.
505 Generate DWARF2 debugging information for each assembler line. This
506 may help debugging assembler code, if the debugger can handle it. Note---this
507 option is only supported by some targets, not all of them.
510 Print a summary of the command line options and exit.
513 Print a summary of all target specific options and exit.
516 Add directory @var{dir} to the search list for @code{.include} directives.
519 Don't warn about signed overflow.
522 @ifclear DIFF-TBL-KLUGE
523 This option is accepted but has no effect on the @value{TARGET} family.
525 @ifset DIFF-TBL-KLUGE
526 Issue warnings when difference tables altered for long displacements.
531 Keep (in the symbol table) local symbols. On traditional a.out systems
532 these start with @samp{L}, but different systems have different local
535 @item --listing-lhs-width=@var{number}
536 Set the maximum width, in words, of the output data column for an assembler
537 listing to @var{number}.
539 @item --listing-lhs-width2=@var{number}
540 Set the maximum width, in words, of the output data column for continuation
541 lines in an assembler listing to @var{number}.
543 @item --listing-rhs-width=@var{number}
544 Set the maximum width of an input source line, as displayed in a listing, to
547 @item --listing-cont-lines=@var{number}
548 Set the maximum number of lines printed in a listing for a single line of input
551 @item -o @var{objfile}
552 Name the object-file output from @command{@value{AS}} @var{objfile}.
555 Fold the data section into the text section.
558 Print the maximum space (in bytes) and total time (in seconds) used by
561 @item --strip-local-absolute
562 Remove local absolute symbols from the outgoing symbol table.
566 Print the @command{as} version.
569 Print the @command{as} version and exit.
573 Suppress warning messages.
575 @item --fatal-warnings
576 Treat warnings as errors.
579 Don't suppress warning messages or treat them as errors.
588 Generate an object file even after errors.
590 @item -- | @var{files} @dots{}
591 Standard input, or source files to assemble.
596 The following options are available when @value{AS} is configured for
601 This option selects the core processor variant.
603 Select either big-endian (-EB) or little-endian (-EL) output.
608 The following options are available when @value{AS} is configured for the ARM
612 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
613 Specify which ARM processor variant is the target.
614 @item -march=@var{architecture}[+@var{extension}@dots{}]
615 Specify which ARM architecture variant is used by the target.
616 @item -mfpu=@var{floating-point-format}
617 Select which Floating Point architecture is the target.
618 @item -mfloat-abi=@var{abi}
619 Select which floating point ABI is in use.
621 Enable Thumb only instruction decoding.
622 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
623 Select which procedure calling convention is in use.
625 Select either big-endian (-EB) or little-endian (-EL) output.
626 @item -mthumb-interwork
627 Specify that the code has been generated with interworking between Thumb and
630 Specify that PIC code has been generated.
635 See the info pages for documentation of the CRIS-specific options.
639 The following options are available when @value{AS} is configured for
642 @cindex D10V optimization
643 @cindex optimization, D10V
645 Optimize output by parallelizing instructions.
650 The following options are available when @value{AS} is configured for a D30V
653 @cindex D30V optimization
654 @cindex optimization, D30V
656 Optimize output by parallelizing instructions.
660 Warn when nops are generated.
662 @cindex D30V nops after 32-bit multiply
664 Warn when a nop after a 32-bit multiply instruction is generated.
669 The following options are available when @value{AS} is configured for the
670 Intel 80960 processor.
673 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
674 Specify which variant of the 960 architecture is the target.
677 Add code to collect statistics about branches taken.
680 Do not alter compare-and-branch instructions for long displacements;
687 The following options are available when @value{AS} is configured for the
693 Specifies that the extended IP2022 instructions are allowed.
696 Restores the default behaviour, which restricts the permitted instructions to
697 just the basic IP2022 ones.
703 The following options are available when @value{AS} is configured for the
704 Renesas M32R (formerly Mitsubishi M32R) series.
709 Specify which processor in the M32R family is the target. The default
710 is normally the M32R, but this option changes it to the M32RX.
712 @item --warn-explicit-parallel-conflicts or --Wp
713 Produce warning messages when questionable parallel constructs are
716 @item --no-warn-explicit-parallel-conflicts or --Wnp
717 Do not produce warning messages when questionable parallel constructs are
724 The following options are available when @value{AS} is configured for the
725 Motorola 68000 series.
730 Shorten references to undefined symbols, to one word instead of two.
732 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
733 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
734 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
735 Specify what processor in the 68000 family is the target. The default
736 is normally the 68020, but this can be changed at configuration time.
738 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
739 The target machine does (or does not) have a floating-point coprocessor.
740 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
741 the basic 68000 is not compatible with the 68881, a combination of the
742 two can be specified, since it's possible to do emulation of the
743 coprocessor instructions with the main processor.
745 @item -m68851 | -mno-68851
746 The target machine does (or does not) have a memory-management
747 unit coprocessor. The default is to assume an MMU for 68020 and up.
754 For details about the PDP-11 machine dependent features options,
755 see @ref{PDP-11-Options}.
758 @item -mpic | -mno-pic
759 Generate position-independent (or position-dependent) code. The
760 default is @option{-mpic}.
763 @itemx -mall-extensions
764 Enable all instruction set extensions. This is the default.
766 @item -mno-extensions
767 Disable all instruction set extensions.
769 @item -m@var{extension} | -mno-@var{extension}
770 Enable (or disable) a particular instruction set extension.
773 Enable the instruction set extensions supported by a particular CPU, and
774 disable all other extensions.
776 @item -m@var{machine}
777 Enable the instruction set extensions supported by a particular machine
778 model, and disable all other extensions.
784 The following options are available when @value{AS} is configured for
785 a picoJava processor.
789 @cindex PJ endianness
790 @cindex endianness, PJ
791 @cindex big endian output, PJ
793 Generate ``big endian'' format output.
795 @cindex little endian output, PJ
797 Generate ``little endian'' format output.
803 The following options are available when @value{AS} is configured for the
804 Motorola 68HC11 or 68HC12 series.
808 @item -m68hc11 | -m68hc12 | -m68hcs12
809 Specify what processor is the target. The default is
810 defined by the configuration option when building the assembler.
813 Specify to use the 16-bit integer ABI.
816 Specify to use the 32-bit integer ABI.
819 Specify to use the 32-bit double ABI.
822 Specify to use the 64-bit double ABI.
824 @item --force-long-branchs
825 Relative branches are turned into absolute ones. This concerns
826 conditional branches, unconditional branches and branches to a
829 @item -S | --short-branchs
830 Do not turn relative branchs into absolute ones
831 when the offset is out of range.
833 @item --strict-direct-mode
834 Do not turn the direct addressing mode into extended addressing mode
835 when the instruction does not support direct addressing mode.
837 @item --print-insn-syntax
838 Print the syntax of instruction in case of error.
840 @item --print-opcodes
841 print the list of instructions with syntax and then exit.
843 @item --generate-example
844 print an example of instruction for each possible instruction and then exit.
845 This option is only useful for testing @command{@value{AS}}.
851 The following options are available when @command{@value{AS}} is configured
852 for the SPARC architecture:
855 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
856 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
857 Explicitly select a variant of the SPARC architecture.
859 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
860 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
862 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
863 UltraSPARC extensions.
865 @item -xarch=v8plus | -xarch=v8plusa
866 For compatibility with the Solaris v9 assembler. These options are
867 equivalent to -Av8plus and -Av8plusa, respectively.
870 Warn when the assembler switches to another architecture.
875 The following options are available when @value{AS} is configured for the 'c54x
880 Enable extended addressing mode. All addresses and relocations will assume
881 extended addressing (usually 23 bits).
882 @item -mcpu=@var{CPU_VERSION}
883 Sets the CPU version being compiled for.
884 @item -merrors-to-file @var{FILENAME}
885 Redirect error output to a file, for broken systems which don't support such
886 behaviour in the shell.
891 The following options are available when @value{AS} is configured for
892 a @sc{mips} processor.
896 This option sets the largest size of an object that can be referenced
897 implicitly with the @code{gp} register. It is only accepted for targets that
898 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
900 @cindex MIPS endianness
901 @cindex endianness, MIPS
902 @cindex big endian output, MIPS
904 Generate ``big endian'' format output.
906 @cindex little endian output, MIPS
908 Generate ``little endian'' format output.
920 Generate code for a particular @sc{mips} Instruction Set Architecture level.
921 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
922 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
923 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
924 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and
926 correspond to generic
927 @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64},
928 and @samp{MIPS64 Release 2}
929 ISA processors, respectively.
931 @item -march=@var{CPU}
932 Generate code for a particular @sc{mips} cpu.
934 @item -mtune=@var{cpu}
935 Schedule and tune for a particular @sc{mips} cpu.
939 Cause nops to be inserted if the read of the destination register
940 of an mfhi or mflo instruction occurs in the following two instructions.
944 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
945 section instead of the standard ELF .stabs sections.
949 Control generation of @code{.pdr} sections.
953 The register sizes are normally inferred from the ISA and ABI, but these
954 flags force a certain group of registers to be treated as 32 bits wide at
955 all times. @samp{-mgp32} controls the size of general-purpose registers
956 and @samp{-mfp32} controls the size of floating-point registers.
960 Generate code for the MIPS 16 processor. This is equivalent to putting
961 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
962 turns off this option.
966 Generate code for the MIPS-3D Application Specific Extension.
967 This tells the assembler to accept MIPS-3D instructions.
968 @samp{-no-mips3d} turns off this option.
972 Generate code for the MDMX Application Specific Extension.
973 This tells the assembler to accept MDMX instructions.
974 @samp{-no-mdmx} turns off this option.
976 @item --construct-floats
977 @itemx --no-construct-floats
978 The @samp{--no-construct-floats} option disables the construction of
979 double width floating point constants by loading the two halves of the
980 value into the two single width floating point registers that make up
981 the double width register. By default @samp{--construct-floats} is
982 selected, allowing construction of these floating point constants.
985 @item --emulation=@var{name}
986 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
987 for some other target, in all respects, including output format (choosing
988 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
989 debugging information or store symbol table information, and default
990 endianness. The available configuration names are: @samp{mipsecoff},
991 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
992 @samp{mipsbelf}. The first two do not alter the default endianness from that
993 of the primary target for which the assembler was configured; the others change
994 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
995 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
996 selection in any case.
998 This option is currently supported only when the primary target
999 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
1000 Furthermore, the primary target or others specified with
1001 @samp{--enable-targets=@dots{}} at configuration time must include support for
1002 the other format, if both are to be available. For example, the Irix 5
1003 configuration includes support for both.
1005 Eventually, this option will support more configurations, with more
1006 fine-grained control over the assembler's behavior, and will be supported for
1010 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1017 Control how to deal with multiplication overflow and division by zero.
1018 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1019 (and only work for Instruction Set Architecture level 2 and higher);
1020 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1024 When this option is used, @command{@value{AS}} will issue a warning every
1025 time it generates a nop instruction from a macro.
1030 The following options are available when @value{AS} is configured for
1036 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1037 The command line option @samp{-nojsri2bsr} can be used to disable it.
1041 Enable or disable the silicon filter behaviour. By default this is disabled.
1042 The default can be overridden by the @samp{-sifilter} command line option.
1045 Alter jump instructions for long displacements.
1047 @item -mcpu=[210|340]
1048 Select the cpu type on the target hardware. This controls which instructions
1052 Assemble for a big endian target.
1055 Assemble for a little endian target.
1061 See the info pages for documentation of the MMIX-specific options.
1065 The following options are available when @value{AS} is configured for
1066 an Xtensa processor.
1069 @item --text-section-literals | --no-text-section-literals
1070 With @option{--text-@-section-@-literals}, literal pools are interspersed
1071 in the text section. The default is
1072 @option{--no-@-text-@-section-@-literals}, which places literals in a
1073 separate section in the output file. These options only affect literals
1074 referenced via PC-relative @code{L32R} instructions; literals for
1075 absolute mode @code{L32R} instructions are handled separately.
1077 @item --absolute-literals | --no-absolute-literals
1078 Indicate to the assembler whether @code{L32R} instructions use absolute
1079 or PC-relative addressing. The default is to assume absolute addressing
1080 if the Xtensa processor includes the absolute @code{L32R} addressing
1081 option. Otherwise, only the PC-relative @code{L32R} mode can be used.
1083 @item --target-align | --no-target-align
1084 Enable or disable automatic alignment to reduce branch penalties at the
1085 expense of some code density. The default is @option{--target-@-align}.
1087 @item --longcalls | --no-longcalls
1088 Enable or disable transformation of call instructions to allow calls
1089 across a greater range of addresses. The default is
1090 @option{--no-@-longcalls}.
1092 @item --transform | --no-transform
1093 Enable or disable all assembler transformations of Xtensa instructions.
1094 The default is @option{--transform};
1095 @option{--no-transform} should be used only in the rare cases when the
1096 instructions must be exactly as specified in the assembly source.
1103 * Manual:: Structure of this Manual
1104 * GNU Assembler:: The GNU Assembler
1105 * Object Formats:: Object File Formats
1106 * Command Line:: Command Line
1107 * Input Files:: Input Files
1108 * Object:: Output (Object) File
1109 * Errors:: Error and Warning Messages
1113 @section Structure of this Manual
1115 @cindex manual, structure and purpose
1116 This manual is intended to describe what you need to know to use
1117 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1118 notation for symbols, constants, and expressions; the directives that
1119 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1122 We also cover special features in the @value{TARGET}
1123 configuration of @command{@value{AS}}, including assembler directives.
1126 This manual also describes some of the machine-dependent features of
1127 various flavors of the assembler.
1130 @cindex machine instructions (not covered)
1131 On the other hand, this manual is @emph{not} intended as an introduction
1132 to programming in assembly language---let alone programming in general!
1133 In a similar vein, we make no attempt to introduce the machine
1134 architecture; we do @emph{not} describe the instruction set, standard
1135 mnemonics, registers or addressing modes that are standard to a
1136 particular architecture.
1138 You may want to consult the manufacturer's
1139 machine architecture manual for this information.
1143 For information on the H8/300 machine instruction set, see @cite{H8/300
1144 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1145 Programming Manual} (Renesas).
1148 For information on the H8/500 machine instruction set, see @cite{H8/500
1149 Series Programming Manual} (Renesas M21T001).
1152 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1153 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1154 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1155 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1158 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1162 @c I think this is premature---doc@cygnus.com, 17jan1991
1164 Throughout this manual, we assume that you are running @dfn{GNU},
1165 the portable operating system from the @dfn{Free Software
1166 Foundation, Inc.}. This restricts our attention to certain kinds of
1167 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1168 once this assumption is granted examples and definitions need less
1171 @command{@value{AS}} is part of a team of programs that turn a high-level
1172 human-readable series of instructions into a low-level
1173 computer-readable series of instructions. Different versions of
1174 @command{@value{AS}} are used for different kinds of computer.
1177 @c There used to be a section "Terminology" here, which defined
1178 @c "contents", "byte", "word", and "long". Defining "word" to any
1179 @c particular size is confusing when the .word directive may generate 16
1180 @c bits on one machine and 32 bits on another; in general, for the user
1181 @c version of this manual, none of these terms seem essential to define.
1182 @c They were used very little even in the former draft of the manual;
1183 @c this draft makes an effort to avoid them (except in names of
1187 @section The GNU Assembler
1189 @c man begin DESCRIPTION
1191 @sc{gnu} @command{as} is really a family of assemblers.
1193 This manual describes @command{@value{AS}}, a member of that family which is
1194 configured for the @value{TARGET} architectures.
1196 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1197 should find a fairly similar environment when you use it on another
1198 architecture. Each version has much in common with the others,
1199 including object file formats, most assembler directives (often called
1200 @dfn{pseudo-ops}) and assembler syntax.@refill
1202 @cindex purpose of @sc{gnu} assembler
1203 @command{@value{AS}} is primarily intended to assemble the output of the
1204 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1205 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1206 assemble correctly everything that other assemblers for the same
1207 machine would assemble.
1209 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1212 @c This remark should appear in generic version of manual; assumption
1213 @c here is that generic version sets M680x0.
1214 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1215 assembler for the same architecture; for example, we know of several
1216 incompatible versions of 680x0 assembly language syntax.
1221 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1222 program in one pass of the source file. This has a subtle impact on the
1223 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1225 @node Object Formats
1226 @section Object File Formats
1228 @cindex object file format
1229 The @sc{gnu} assembler can be configured to produce several alternative
1230 object file formats. For the most part, this does not affect how you
1231 write assembly language programs; but directives for debugging symbols
1232 are typically different in different file formats. @xref{Symbol
1233 Attributes,,Symbol Attributes}.
1236 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1237 @value{OBJ-NAME} format object files.
1239 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1241 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1242 @code{a.out} or COFF format object files.
1245 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1246 @code{b.out} or COFF format object files.
1249 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1250 SOM or ELF format object files.
1255 @section Command Line
1257 @cindex command line conventions
1259 After the program name @command{@value{AS}}, the command line may contain
1260 options and file names. Options may appear in any order, and may be
1261 before, after, or between file names. The order of file names is
1264 @cindex standard input, as input file
1266 @file{--} (two hyphens) by itself names the standard input file
1267 explicitly, as one of the files for @command{@value{AS}} to assemble.
1269 @cindex options, command line
1270 Except for @samp{--} any command line argument that begins with a
1271 hyphen (@samp{-}) is an option. Each option changes the behavior of
1272 @command{@value{AS}}. No option changes the way another option works. An
1273 option is a @samp{-} followed by one or more letters; the case of
1274 the letter is important. All options are optional.
1276 Some options expect exactly one file name to follow them. The file
1277 name may either immediately follow the option's letter (compatible
1278 with older assemblers) or it may be the next command argument (@sc{gnu}
1279 standard). These two command lines are equivalent:
1282 @value{AS} -o my-object-file.o mumble.s
1283 @value{AS} -omy-object-file.o mumble.s
1287 @section Input Files
1290 @cindex source program
1291 @cindex files, input
1292 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1293 describe the program input to one run of @command{@value{AS}}. The program may
1294 be in one or more files; how the source is partitioned into files
1295 doesn't change the meaning of the source.
1297 @c I added "con" prefix to "catenation" just to prove I can overcome my
1298 @c APL training... doc@cygnus.com
1299 The source program is a concatenation of the text in all the files, in the
1302 @c man begin DESCRIPTION
1303 Each time you run @command{@value{AS}} it assembles exactly one source
1304 program. The source program is made up of one or more files.
1305 (The standard input is also a file.)
1307 You give @command{@value{AS}} a command line that has zero or more input file
1308 names. The input files are read (from left file name to right). A
1309 command line argument (in any position) that has no special meaning
1310 is taken to be an input file name.
1312 If you give @command{@value{AS}} no file names it attempts to read one input file
1313 from the @command{@value{AS}} standard input, which is normally your terminal. You
1314 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1317 Use @samp{--} if you need to explicitly name the standard input file
1318 in your command line.
1320 If the source is empty, @command{@value{AS}} produces a small, empty object
1325 @subheading Filenames and Line-numbers
1327 @cindex input file linenumbers
1328 @cindex line numbers, in input files
1329 There are two ways of locating a line in the input file (or files) and
1330 either may be used in reporting error messages. One way refers to a line
1331 number in a physical file; the other refers to a line number in a
1332 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1334 @dfn{Physical files} are those files named in the command line given
1335 to @command{@value{AS}}.
1337 @dfn{Logical files} are simply names declared explicitly by assembler
1338 directives; they bear no relation to physical files. Logical file names help
1339 error messages reflect the original source file, when @command{@value{AS}} source
1340 is itself synthesized from other files. @command{@value{AS}} understands the
1341 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1342 @ref{File,,@code{.file}}.
1345 @section Output (Object) File
1351 Every time you run @command{@value{AS}} it produces an output file, which is
1352 your assembly language program translated into numbers. This file
1353 is the object file. Its default name is
1361 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1363 You can give it another name by using the @option{-o} option. Conventionally,
1364 object file names end with @file{.o}. The default name is used for historical
1365 reasons: older assemblers were capable of assembling self-contained programs
1366 directly into a runnable program. (For some formats, this isn't currently
1367 possible, but it can be done for the @code{a.out} format.)
1371 The object file is meant for input to the linker @code{@value{LD}}. It contains
1372 assembled program code, information to help @code{@value{LD}} integrate
1373 the assembled program into a runnable file, and (optionally) symbolic
1374 information for the debugger.
1376 @c link above to some info file(s) like the description of a.out.
1377 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1380 @section Error and Warning Messages
1382 @c man begin DESCRIPTION
1384 @cindex error messages
1385 @cindex warning messages
1386 @cindex messages from assembler
1387 @command{@value{AS}} may write warnings and error messages to the standard error
1388 file (usually your terminal). This should not happen when a compiler
1389 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1390 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1391 grave problem that stops the assembly.
1395 @cindex format of warning messages
1396 Warning messages have the format
1399 file_name:@b{NNN}:Warning Message Text
1403 @cindex line numbers, in warnings/errors
1404 (where @b{NNN} is a line number). If a logical file name has been given
1405 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1406 the current input file is used. If a logical line number was given
1408 (@pxref{Line,,@code{.line}})
1412 (@pxref{Line,,@code{.line}})
1415 (@pxref{Ln,,@code{.ln}})
1418 then it is used to calculate the number printed,
1419 otherwise the actual line in the current source file is printed. The
1420 message text is intended to be self explanatory (in the grand Unix
1423 @cindex format of error messages
1424 Error messages have the format
1426 file_name:@b{NNN}:FATAL:Error Message Text
1428 The file name and line number are derived as for warning
1429 messages. The actual message text may be rather less explanatory
1430 because many of them aren't supposed to happen.
1433 @chapter Command-Line Options
1435 @cindex options, all versions of assembler
1436 This chapter describes command-line options available in @emph{all}
1437 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1439 to the @value{TARGET} target.
1442 to particular machine architectures.
1445 @c man begin DESCRIPTION
1447 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
1448 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1449 The assembler arguments must be separated from each other (and the @samp{-Wa})
1450 by commas. For example:
1453 gcc -c -g -O -Wa,-alh,-L file.c
1457 This passes two options to the assembler: @samp{-alh} (emit a listing to
1458 standard output with high-level and assembly source) and @samp{-L} (retain
1459 local symbols in the symbol table).
1461 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1462 command-line options are automatically passed to the assembler by the compiler.
1463 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1464 precisely what options it passes to each compilation pass, including the
1470 * a:: -a[cdhlns] enable listings
1471 * alternate:: --alternate enable alternate macro syntax
1472 * D:: -D for compatibility
1473 * f:: -f to work faster
1474 * I:: -I for .include search path
1475 @ifclear DIFF-TBL-KLUGE
1476 * K:: -K for compatibility
1478 @ifset DIFF-TBL-KLUGE
1479 * K:: -K for difference tables
1482 * L:: -L to retain local labels
1483 * listing:: --listing-XXX to configure listing output
1484 * M:: -M or --mri to assemble in MRI compatibility mode
1485 * MD:: --MD for dependency tracking
1486 * o:: -o to name the object file
1487 * R:: -R to join data and text sections
1488 * statistics:: --statistics to see statistics about assembly
1489 * traditional-format:: --traditional-format for compatible output
1490 * v:: -v to announce version
1491 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1492 * Z:: -Z to make object file even after errors
1496 @section Enable Listings: @option{-a[cdhlns]}
1505 @cindex listings, enabling
1506 @cindex assembly listings, enabling
1508 These options enable listing output from the assembler. By itself,
1509 @samp{-a} requests high-level, assembly, and symbols listing.
1510 You can use other letters to select specific options for the list:
1511 @samp{-ah} requests a high-level language listing,
1512 @samp{-al} requests an output-program assembly listing, and
1513 @samp{-as} requests a symbol table listing.
1514 High-level listings require that a compiler debugging option like
1515 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1518 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1519 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1520 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1521 omitted from the listing.
1523 Use the @samp{-ad} option to omit debugging directives from the
1526 Once you have specified one of these options, you can further control
1527 listing output and its appearance using the directives @code{.list},
1528 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1530 The @samp{-an} option turns off all forms processing.
1531 If you do not request listing output with one of the @samp{-a} options, the
1532 listing-control directives have no effect.
1534 The letters after @samp{-a} may be combined into one option,
1535 @emph{e.g.}, @samp{-aln}.
1537 Note if the assembler source is coming from the standard input (eg because it
1538 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1539 is being used) then the listing will not contain any comments or preprocessor
1540 directives. This is because the listing code buffers input source lines from
1541 stdin only after they have been preprocessed by the assembler. This reduces
1542 memory usage and makes the code more efficient.
1545 @section @option{--alternate}
1548 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
1551 @section @option{-D}
1554 This option has no effect whatsoever, but it is accepted to make it more
1555 likely that scripts written for other assemblers also work with
1556 @command{@value{AS}}.
1559 @section Work Faster: @option{-f}
1562 @cindex trusted compiler
1563 @cindex faster processing (@option{-f})
1564 @samp{-f} should only be used when assembling programs written by a
1565 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1566 and comment preprocessing on
1567 the input file(s) before assembling them. @xref{Preprocessing,
1571 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1572 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1577 @section @code{.include} Search Path: @option{-I} @var{path}
1579 @kindex -I @var{path}
1580 @cindex paths for @code{.include}
1581 @cindex search path for @code{.include}
1582 @cindex @code{include} directive search path
1583 Use this option to add a @var{path} to the list of directories
1584 @command{@value{AS}} searches for files specified in @code{.include}
1585 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1586 many times as necessary to include a variety of paths. The current
1587 working directory is always searched first; after that, @command{@value{AS}}
1588 searches any @samp{-I} directories in the same order as they were
1589 specified (left to right) on the command line.
1592 @section Difference Tables: @option{-K}
1595 @ifclear DIFF-TBL-KLUGE
1596 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1597 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1598 where it can be used to warn when the assembler alters the machine code
1599 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1600 family does not have the addressing limitations that sometimes lead to this
1601 alteration on other platforms.
1604 @ifset DIFF-TBL-KLUGE
1605 @cindex difference tables, warning
1606 @cindex warning for altered difference tables
1607 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1608 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1609 You can use the @samp{-K} option if you want a warning issued when this
1614 @section Include Local Labels: @option{-L}
1617 @cindex local labels, retaining in output
1618 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1619 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1620 debugging, because they are intended for the use of programs (like
1621 compilers) that compose assembler programs, not for your notice.
1622 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1623 normally debug with them.
1625 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1626 in the object file. Usually if you do this you also tell the linker
1627 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1629 By default, a local label is any label beginning with @samp{L}, but each
1630 target is allowed to redefine the local label prefix.
1632 On the HPPA local labels begin with @samp{L$}.
1636 @section Configuring listing output: @option{--listing}
1638 The listing feature of the assembler can be enabled via the command line switch
1639 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1640 hex dump of the corresponding locations in the output object file, and displays
1641 them as a listing file. The format of this listing can be controlled by pseudo
1642 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1643 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1646 @item --listing-lhs-width=@samp{number}
1647 @kindex --listing-lhs-width
1648 @cindex Width of first line disassembly output
1649 Sets the maximum width, in words, of the first line of the hex byte dump. This
1650 dump appears on the left hand side of the listing output.
1652 @item --listing-lhs-width2=@samp{number}
1653 @kindex --listing-lhs-width2
1654 @cindex Width of continuation lines of disassembly output
1655 Sets the maximum width, in words, of any further lines of the hex byte dump for
1656 a given input source line. If this value is not specified, it defaults to being
1657 the same as the value specified for @samp{--listing-lhs-width}. If neither
1658 switch is used the default is to one.
1660 @item --listing-rhs-width=@samp{number}
1661 @kindex --listing-rhs-width
1662 @cindex Width of source line output
1663 Sets the maximum width, in characters, of the source line that is displayed
1664 alongside the hex dump. The default value for this parameter is 100. The
1665 source line is displayed on the right hand side of the listing output.
1667 @item --listing-cont-lines=@samp{number}
1668 @kindex --listing-cont-lines
1669 @cindex Maximum number of continuation lines
1670 Sets the maximum number of continuation lines of hex dump that will be
1671 displayed for a given single line of source input. The default value is 4.
1675 @section Assemble in MRI Compatibility Mode: @option{-M}
1678 @cindex MRI compatibility mode
1679 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1680 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1681 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1682 configured target) assembler from Microtec Research. The exact nature of the
1683 MRI syntax will not be documented here; see the MRI manuals for more
1684 information. Note in particular that the handling of macros and macro
1685 arguments is somewhat different. The purpose of this option is to permit
1686 assembling existing MRI assembler code using @command{@value{AS}}.
1688 The MRI compatibility is not complete. Certain operations of the MRI assembler
1689 depend upon its object file format, and can not be supported using other object
1690 file formats. Supporting these would require enhancing each object file format
1691 individually. These are:
1694 @item global symbols in common section
1696 The m68k MRI assembler supports common sections which are merged by the linker.
1697 Other object file formats do not support this. @command{@value{AS}} handles
1698 common sections by treating them as a single common symbol. It permits local
1699 symbols to be defined within a common section, but it can not support global
1700 symbols, since it has no way to describe them.
1702 @item complex relocations
1704 The MRI assemblers support relocations against a negated section address, and
1705 relocations which combine the start addresses of two or more sections. These
1706 are not support by other object file formats.
1708 @item @code{END} pseudo-op specifying start address
1710 The MRI @code{END} pseudo-op permits the specification of a start address.
1711 This is not supported by other object file formats. The start address may
1712 instead be specified using the @option{-e} option to the linker, or in a linker
1715 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1717 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1718 name to the output file. This is not supported by other object file formats.
1720 @item @code{ORG} pseudo-op
1722 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1723 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1724 which changes the location within the current section. Absolute sections are
1725 not supported by other object file formats. The address of a section may be
1726 assigned within a linker script.
1729 There are some other features of the MRI assembler which are not supported by
1730 @command{@value{AS}}, typically either because they are difficult or because they
1731 seem of little consequence. Some of these may be supported in future releases.
1735 @item EBCDIC strings
1737 EBCDIC strings are not supported.
1739 @item packed binary coded decimal
1741 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1742 and @code{DCB.P} pseudo-ops are not supported.
1744 @item @code{FEQU} pseudo-op
1746 The m68k @code{FEQU} pseudo-op is not supported.
1748 @item @code{NOOBJ} pseudo-op
1750 The m68k @code{NOOBJ} pseudo-op is not supported.
1752 @item @code{OPT} branch control options
1754 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1755 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1756 relaxes all branches, whether forward or backward, to an appropriate size, so
1757 these options serve no purpose.
1759 @item @code{OPT} list control options
1761 The following m68k @code{OPT} list control options are ignored: @code{C},
1762 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1763 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1765 @item other @code{OPT} options
1767 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1768 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1770 @item @code{OPT} @code{D} option is default
1772 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1773 @code{OPT NOD} may be used to turn it off.
1775 @item @code{XREF} pseudo-op.
1777 The m68k @code{XREF} pseudo-op is ignored.
1779 @item @code{.debug} pseudo-op
1781 The i960 @code{.debug} pseudo-op is not supported.
1783 @item @code{.extended} pseudo-op
1785 The i960 @code{.extended} pseudo-op is not supported.
1787 @item @code{.list} pseudo-op.
1789 The various options of the i960 @code{.list} pseudo-op are not supported.
1791 @item @code{.optimize} pseudo-op
1793 The i960 @code{.optimize} pseudo-op is not supported.
1795 @item @code{.output} pseudo-op
1797 The i960 @code{.output} pseudo-op is not supported.
1799 @item @code{.setreal} pseudo-op
1801 The i960 @code{.setreal} pseudo-op is not supported.
1806 @section Dependency Tracking: @option{--MD}
1809 @cindex dependency tracking
1812 @command{@value{AS}} can generate a dependency file for the file it creates. This
1813 file consists of a single rule suitable for @code{make} describing the
1814 dependencies of the main source file.
1816 The rule is written to the file named in its argument.
1818 This feature is used in the automatic updating of makefiles.
1821 @section Name the Object File: @option{-o}
1824 @cindex naming object file
1825 @cindex object file name
1826 There is always one object file output when you run @command{@value{AS}}. By
1827 default it has the name
1830 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1844 You use this option (which takes exactly one filename) to give the
1845 object file a different name.
1847 Whatever the object file is called, @command{@value{AS}} overwrites any
1848 existing file of the same name.
1851 @section Join Data and Text Sections: @option{-R}
1854 @cindex data and text sections, joining
1855 @cindex text and data sections, joining
1856 @cindex joining text and data sections
1857 @cindex merging text and data sections
1858 @option{-R} tells @command{@value{AS}} to write the object file as if all
1859 data-section data lives in the text section. This is only done at
1860 the very last moment: your binary data are the same, but data
1861 section parts are relocated differently. The data section part of
1862 your object file is zero bytes long because all its bytes are
1863 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1865 When you specify @option{-R} it would be possible to generate shorter
1866 address displacements (because we do not have to cross between text and
1867 data section). We refrain from doing this simply for compatibility with
1868 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1871 When @command{@value{AS}} is configured for COFF or ELF output,
1872 this option is only useful if you use sections named @samp{.text} and
1877 @option{-R} is not supported for any of the HPPA targets. Using
1878 @option{-R} generates a warning from @command{@value{AS}}.
1882 @section Display Assembly Statistics: @option{--statistics}
1884 @kindex --statistics
1885 @cindex statistics, about assembly
1886 @cindex time, total for assembly
1887 @cindex space used, maximum for assembly
1888 Use @samp{--statistics} to display two statistics about the resources used by
1889 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1890 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1893 @node traditional-format
1894 @section Compatible Output: @option{--traditional-format}
1896 @kindex --traditional-format
1897 For some targets, the output of @command{@value{AS}} is different in some ways
1898 from the output of some existing assembler. This switch requests
1899 @command{@value{AS}} to use the traditional format instead.
1901 For example, it disables the exception frame optimizations which
1902 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1905 @section Announce Version: @option{-v}
1909 @cindex assembler version
1910 @cindex version of assembler
1911 You can find out what version of as is running by including the
1912 option @samp{-v} (which you can also spell as @samp{-version}) on the
1916 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1918 @command{@value{AS}} should never give a warning or error message when
1919 assembling compiler output. But programs written by people often
1920 cause @command{@value{AS}} to give a warning that a particular assumption was
1921 made. All such warnings are directed to the standard error file.
1925 @cindex suppressing warnings
1926 @cindex warnings, suppressing
1927 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1928 This only affects the warning messages: it does not change any particular of
1929 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1932 @kindex --fatal-warnings
1933 @cindex errors, caused by warnings
1934 @cindex warnings, causing error
1935 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1936 files that generate warnings to be in error.
1939 @cindex warnings, switching on
1940 You can switch these options off again by specifying @option{--warn}, which
1941 causes warnings to be output as usual.
1944 @section Generate Object File in Spite of Errors: @option{-Z}
1945 @cindex object file, after errors
1946 @cindex errors, continuing after
1947 After an error message, @command{@value{AS}} normally produces no output. If for
1948 some reason you are interested in object file output even after
1949 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1950 option. If there are any errors, @command{@value{AS}} continues anyways, and
1951 writes an object file after a final warning message of the form @samp{@var{n}
1952 errors, @var{m} warnings, generating bad object file.}
1957 @cindex machine-independent syntax
1958 @cindex syntax, machine-independent
1959 This chapter describes the machine-independent syntax allowed in a
1960 source file. @command{@value{AS}} syntax is similar to what many other
1961 assemblers use; it is inspired by the BSD 4.2
1966 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1970 * Preprocessing:: Preprocessing
1971 * Whitespace:: Whitespace
1972 * Comments:: Comments
1973 * Symbol Intro:: Symbols
1974 * Statements:: Statements
1975 * Constants:: Constants
1979 @section Preprocessing
1981 @cindex preprocessing
1982 The @command{@value{AS}} internal preprocessor:
1984 @cindex whitespace, removed by preprocessor
1986 adjusts and removes extra whitespace. It leaves one space or tab before
1987 the keywords on a line, and turns any other whitespace on the line into
1990 @cindex comments, removed by preprocessor
1992 removes all comments, replacing them with a single space, or an
1993 appropriate number of newlines.
1995 @cindex constants, converted by preprocessor
1997 converts character constants into the appropriate numeric values.
2000 It does not do macro processing, include file handling, or
2001 anything else you may get from your C compiler's preprocessor. You can
2002 do include file processing with the @code{.include} directive
2003 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2004 to get other ``CPP'' style preprocessing by giving the input file a
2005 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
2006 Output, gcc.info, Using GNU CC}.
2008 Excess whitespace, comments, and character constants
2009 cannot be used in the portions of the input text that are not
2012 @cindex turning preprocessing on and off
2013 @cindex preprocessing, turning on and off
2016 If the first line of an input file is @code{#NO_APP} or if you use the
2017 @samp{-f} option, whitespace and comments are not removed from the input file.
2018 Within an input file, you can ask for whitespace and comment removal in
2019 specific portions of the by putting a line that says @code{#APP} before the
2020 text that may contain whitespace or comments, and putting a line that says
2021 @code{#NO_APP} after this text. This feature is mainly intend to support
2022 @code{asm} statements in compilers whose output is otherwise free of comments
2029 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2030 Whitespace is used to separate symbols, and to make programs neater for
2031 people to read. Unless within character constants
2032 (@pxref{Characters,,Character Constants}), any whitespace means the same
2033 as exactly one space.
2039 There are two ways of rendering comments to @command{@value{AS}}. In both
2040 cases the comment is equivalent to one space.
2042 Anything from @samp{/*} through the next @samp{*/} is a comment.
2043 This means you may not nest these comments.
2047 The only way to include a newline ('\n') in a comment
2048 is to use this sort of comment.
2051 /* This sort of comment does not nest. */
2054 @cindex line comment character
2055 Anything from the @dfn{line comment} character to the next newline
2056 is considered a comment and is ignored. The line comment character is
2058 @samp{;} for the AMD 29K family;
2061 @samp{;} on the ARC;
2064 @samp{@@} on the ARM;
2067 @samp{;} for the H8/300 family;
2070 @samp{!} for the H8/500 family;
2073 @samp{;} for the HPPA;
2076 @samp{#} on the i386 and x86-64;
2079 @samp{#} on the i960;
2082 @samp{;} for the PDP-11;
2085 @samp{;} for picoJava;
2088 @samp{#} for Motorola PowerPC;
2091 @samp{!} for the Renesas / SuperH SH;
2094 @samp{!} on the SPARC;
2097 @samp{#} on the ip2k;
2100 @samp{#} on the m32r;
2103 @samp{|} on the 680x0;
2106 @samp{#} on the 68HC11 and 68HC12;
2109 @samp{;} on the M880x0;
2112 @samp{#} on the Vax;
2115 @samp{!} for the Z8000;
2118 @samp{#} on the V850;
2121 @samp{#} for Xtensa systems;
2123 see @ref{Machine Dependencies}. @refill
2124 @c FIXME What about i860?
2127 On some machines there are two different line comment characters. One
2128 character only begins a comment if it is the first non-whitespace character on
2129 a line, while the other always begins a comment.
2133 The V850 assembler also supports a double dash as starting a comment that
2134 extends to the end of the line.
2140 @cindex lines starting with @code{#}
2141 @cindex logical line numbers
2142 To be compatible with past assemblers, lines that begin with @samp{#} have a
2143 special interpretation. Following the @samp{#} should be an absolute
2144 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2145 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
2146 new logical file name. The rest of the line, if any, should be whitespace.
2148 If the first non-whitespace characters on the line are not numeric,
2149 the line is ignored. (Just like a comment.)
2152 # This is an ordinary comment.
2153 # 42-6 "new_file_name" # New logical file name
2154 # This is logical line # 36.
2156 This feature is deprecated, and may disappear from future versions
2157 of @command{@value{AS}}.
2162 @cindex characters used in symbols
2163 @ifclear SPECIAL-SYMS
2164 A @dfn{symbol} is one or more characters chosen from the set of all
2165 letters (both upper and lower case), digits and the three characters
2171 A @dfn{symbol} is one or more characters chosen from the set of all
2172 letters (both upper and lower case), digits and the three characters
2173 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2179 On most machines, you can also use @code{$} in symbol names; exceptions
2180 are noted in @ref{Machine Dependencies}.
2182 No symbol may begin with a digit. Case is significant.
2183 There is no length limit: all characters are significant. Symbols are
2184 delimited by characters not in that set, or by the beginning of a file
2185 (since the source program must end with a newline, the end of a file is
2186 not a possible symbol delimiter). @xref{Symbols}.
2187 @cindex length of symbols
2192 @cindex statements, structure of
2193 @cindex line separator character
2194 @cindex statement separator character
2196 @ifclear abnormal-separator
2197 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2198 semicolon (@samp{;}). The newline or semicolon is considered part of
2199 the preceding statement. Newlines and semicolons within character
2200 constants are an exception: they do not end statements.
2202 @ifset abnormal-separator
2204 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2205 sign (@samp{@@}). The newline or at sign is considered part of the
2206 preceding statement. Newlines and at signs within character constants
2207 are an exception: they do not end statements.
2210 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2211 point (@samp{!}). The newline or exclamation point is considered part of the
2212 preceding statement. Newlines and exclamation points within character
2213 constants are an exception: they do not end statements.
2216 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2217 H8/300) a dollar sign (@samp{$}); or (for the
2220 (@samp{;}). The newline or separator character is considered part of
2221 the preceding statement. Newlines and separators within character
2222 constants are an exception: they do not end statements.
2227 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2228 separator character. (The line separator is usually @samp{;}, unless
2229 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2230 newline or separator character is considered part of the preceding
2231 statement. Newlines and separators within character constants are an
2232 exception: they do not end statements.
2235 @cindex newline, required at file end
2236 @cindex EOF, newline must precede
2237 It is an error to end any statement with end-of-file: the last
2238 character of any input file should be a newline.@refill
2240 An empty statement is allowed, and may include whitespace. It is ignored.
2242 @cindex instructions and directives
2243 @cindex directives and instructions
2244 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2245 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2247 A statement begins with zero or more labels, optionally followed by a
2248 key symbol which determines what kind of statement it is. The key
2249 symbol determines the syntax of the rest of the statement. If the
2250 symbol begins with a dot @samp{.} then the statement is an assembler
2251 directive: typically valid for any computer. If the symbol begins with
2252 a letter the statement is an assembly language @dfn{instruction}: it
2253 assembles into a machine language instruction.
2255 Different versions of @command{@value{AS}} for different computers
2256 recognize different instructions. In fact, the same symbol may
2257 represent a different instruction in a different computer's assembly
2261 @cindex @code{:} (label)
2262 @cindex label (@code{:})
2263 A label is a symbol immediately followed by a colon (@code{:}).
2264 Whitespace before a label or after a colon is permitted, but you may not
2265 have whitespace between a label's symbol and its colon. @xref{Labels}.
2268 For HPPA targets, labels need not be immediately followed by a colon, but
2269 the definition of a label must begin in column zero. This also implies that
2270 only one label may be defined on each line.
2274 label: .directive followed by something
2275 another_label: # This is an empty statement.
2276 instruction operand_1, operand_2, @dots{}
2283 A constant is a number, written so that its value is known by
2284 inspection, without knowing any context. Like this:
2287 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2288 .ascii "Ring the bell\7" # A string constant.
2289 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2290 .float 0f-314159265358979323846264338327\
2291 95028841971.693993751E-40 # - pi, a flonum.
2296 * Characters:: Character Constants
2297 * Numbers:: Number Constants
2301 @subsection Character Constants
2303 @cindex character constants
2304 @cindex constants, character
2305 There are two kinds of character constants. A @dfn{character} stands
2306 for one character in one byte and its value may be used in
2307 numeric expressions. String constants (properly called string
2308 @emph{literals}) are potentially many bytes and their values may not be
2309 used in arithmetic expressions.
2313 * Chars:: Characters
2317 @subsubsection Strings
2319 @cindex string constants
2320 @cindex constants, string
2321 A @dfn{string} is written between double-quotes. It may contain
2322 double-quotes or null characters. The way to get special characters
2323 into a string is to @dfn{escape} these characters: precede them with
2324 a backslash @samp{\} character. For example @samp{\\} represents
2325 one backslash: the first @code{\} is an escape which tells
2326 @command{@value{AS}} to interpret the second character literally as a backslash
2327 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2328 escape character). The complete list of escapes follows.
2330 @cindex escape codes, character
2331 @cindex character escape codes
2334 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2336 @cindex @code{\b} (backspace character)
2337 @cindex backspace (@code{\b})
2339 Mnemonic for backspace; for ASCII this is octal code 010.
2342 @c Mnemonic for EOText; for ASCII this is octal code 004.
2344 @cindex @code{\f} (formfeed character)
2345 @cindex formfeed (@code{\f})
2347 Mnemonic for FormFeed; for ASCII this is octal code 014.
2349 @cindex @code{\n} (newline character)
2350 @cindex newline (@code{\n})
2352 Mnemonic for newline; for ASCII this is octal code 012.
2355 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2357 @cindex @code{\r} (carriage return character)
2358 @cindex carriage return (@code{\r})
2360 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2363 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2364 @c other assemblers.
2366 @cindex @code{\t} (tab)
2367 @cindex tab (@code{\t})
2369 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2372 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2373 @c @item \x @var{digit} @var{digit} @var{digit}
2374 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2376 @cindex @code{\@var{ddd}} (octal character code)
2377 @cindex octal character code (@code{\@var{ddd}})
2378 @item \ @var{digit} @var{digit} @var{digit}
2379 An octal character code. The numeric code is 3 octal digits.
2380 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2381 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2383 @cindex @code{\@var{xd...}} (hex character code)
2384 @cindex hex character code (@code{\@var{xd...}})
2385 @item \@code{x} @var{hex-digits...}
2386 A hex character code. All trailing hex digits are combined. Either upper or
2387 lower case @code{x} works.
2389 @cindex @code{\\} (@samp{\} character)
2390 @cindex backslash (@code{\\})
2392 Represents one @samp{\} character.
2395 @c Represents one @samp{'} (accent acute) character.
2396 @c This is needed in single character literals
2397 @c (@xref{Characters,,Character Constants}.) to represent
2400 @cindex @code{\"} (doublequote character)
2401 @cindex doublequote (@code{\"})
2403 Represents one @samp{"} character. Needed in strings to represent
2404 this character, because an unescaped @samp{"} would end the string.
2406 @item \ @var{anything-else}
2407 Any other character when escaped by @kbd{\} gives a warning, but
2408 assembles as if the @samp{\} was not present. The idea is that if
2409 you used an escape sequence you clearly didn't want the literal
2410 interpretation of the following character. However @command{@value{AS}} has no
2411 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2412 code and warns you of the fact.
2415 Which characters are escapable, and what those escapes represent,
2416 varies widely among assemblers. The current set is what we think
2417 the BSD 4.2 assembler recognizes, and is a subset of what most C
2418 compilers recognize. If you are in doubt, do not use an escape
2422 @subsubsection Characters
2424 @cindex single character constant
2425 @cindex character, single
2426 @cindex constant, single character
2427 A single character may be written as a single quote immediately
2428 followed by that character. The same escapes apply to characters as
2429 to strings. So if you want to write the character backslash, you
2430 must write @kbd{'\\} where the first @code{\} escapes the second
2431 @code{\}. As you can see, the quote is an acute accent, not a
2432 grave accent. A newline
2434 @ifclear abnormal-separator
2435 (or semicolon @samp{;})
2437 @ifset abnormal-separator
2439 (or at sign @samp{@@})
2442 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2443 Renesas SH or H8/500)
2447 immediately following an acute accent is taken as a literal character
2448 and does not count as the end of a statement. The value of a character
2449 constant in a numeric expression is the machine's byte-wide code for
2450 that character. @command{@value{AS}} assumes your character code is ASCII:
2451 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2454 @subsection Number Constants
2456 @cindex constants, number
2457 @cindex number constants
2458 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2459 are stored in the target machine. @emph{Integers} are numbers that
2460 would fit into an @code{int} in the C language. @emph{Bignums} are
2461 integers, but they are stored in more than 32 bits. @emph{Flonums}
2462 are floating point numbers, described below.
2465 * Integers:: Integers
2470 * Bit Fields:: Bit Fields
2476 @subsubsection Integers
2478 @cindex constants, integer
2480 @cindex binary integers
2481 @cindex integers, binary
2482 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2483 the binary digits @samp{01}.
2485 @cindex octal integers
2486 @cindex integers, octal
2487 An octal integer is @samp{0} followed by zero or more of the octal
2488 digits (@samp{01234567}).
2490 @cindex decimal integers
2491 @cindex integers, decimal
2492 A decimal integer starts with a non-zero digit followed by zero or
2493 more digits (@samp{0123456789}).
2495 @cindex hexadecimal integers
2496 @cindex integers, hexadecimal
2497 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2498 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2500 Integers have the usual values. To denote a negative integer, use
2501 the prefix operator @samp{-} discussed under expressions
2502 (@pxref{Prefix Ops,,Prefix Operators}).
2505 @subsubsection Bignums
2508 @cindex constants, bignum
2509 A @dfn{bignum} has the same syntax and semantics as an integer
2510 except that the number (or its negative) takes more than 32 bits to
2511 represent in binary. The distinction is made because in some places
2512 integers are permitted while bignums are not.
2515 @subsubsection Flonums
2517 @cindex floating point numbers
2518 @cindex constants, floating point
2520 @cindex precision, floating point
2521 A @dfn{flonum} represents a floating point number. The translation is
2522 indirect: a decimal floating point number from the text is converted by
2523 @command{@value{AS}} to a generic binary floating point number of more than
2524 sufficient precision. This generic floating point number is converted
2525 to a particular computer's floating point format (or formats) by a
2526 portion of @command{@value{AS}} specialized to that computer.
2528 A flonum is written by writing (in order)
2533 (@samp{0} is optional on the HPPA.)
2537 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2539 @kbd{e} is recommended. Case is not important.
2541 @c FIXME: verify if flonum syntax really this vague for most cases
2542 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2543 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2546 On the H8/300, H8/500,
2547 Renesas / SuperH SH,
2548 and AMD 29K architectures, the letter must be
2549 one of the letters @samp{DFPRSX} (in upper or lower case).
2551 On the ARC, the letter must be one of the letters @samp{DFRS}
2552 (in upper or lower case).
2554 On the Intel 960 architecture, the letter must be
2555 one of the letters @samp{DFT} (in upper or lower case).
2557 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2561 One of the letters @samp{DFPRSX} (in upper or lower case).
2564 One of the letters @samp{DFRS} (in upper or lower case).
2567 One of the letters @samp{DFPRSX} (in upper or lower case).
2570 The letter @samp{E} (upper case only).
2573 One of the letters @samp{DFT} (in upper or lower case).
2578 An optional sign: either @samp{+} or @samp{-}.
2581 An optional @dfn{integer part}: zero or more decimal digits.
2584 An optional @dfn{fractional part}: @samp{.} followed by zero
2585 or more decimal digits.
2588 An optional exponent, consisting of:
2592 An @samp{E} or @samp{e}.
2593 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2594 @c principle this can perfectly well be different on different targets.
2596 Optional sign: either @samp{+} or @samp{-}.
2598 One or more decimal digits.
2603 At least one of the integer part or the fractional part must be
2604 present. The floating point number has the usual base-10 value.
2606 @command{@value{AS}} does all processing using integers. Flonums are computed
2607 independently of any floating point hardware in the computer running
2608 @command{@value{AS}}.
2612 @c Bit fields are written as a general facility but are also controlled
2613 @c by a conditional-compilation flag---which is as of now (21mar91)
2614 @c turned on only by the i960 config of GAS.
2616 @subsubsection Bit Fields
2619 @cindex constants, bit field
2620 You can also define numeric constants as @dfn{bit fields}.
2621 specify two numbers separated by a colon---
2623 @var{mask}:@var{value}
2626 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2629 The resulting number is then packed
2631 @c this conditional paren in case bit fields turned on elsewhere than 960
2632 (in host-dependent byte order)
2634 into a field whose width depends on which assembler directive has the
2635 bit-field as its argument. Overflow (a result from the bitwise and
2636 requiring more binary digits to represent) is not an error; instead,
2637 more constants are generated, of the specified width, beginning with the
2638 least significant digits.@refill
2640 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2641 @code{.short}, and @code{.word} accept bit-field arguments.
2646 @chapter Sections and Relocation
2651 * Secs Background:: Background
2652 * Ld Sections:: Linker Sections
2653 * As Sections:: Assembler Internal Sections
2654 * Sub-Sections:: Sub-Sections
2658 @node Secs Background
2661 Roughly, a section is a range of addresses, with no gaps; all data
2662 ``in'' those addresses is treated the same for some particular purpose.
2663 For example there may be a ``read only'' section.
2665 @cindex linker, and assembler
2666 @cindex assembler, and linker
2667 The linker @code{@value{LD}} reads many object files (partial programs) and
2668 combines their contents to form a runnable program. When @command{@value{AS}}
2669 emits an object file, the partial program is assumed to start at address 0.
2670 @code{@value{LD}} assigns the final addresses for the partial program, so that
2671 different partial programs do not overlap. This is actually an
2672 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2675 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2676 addresses. These blocks slide to their run-time addresses as rigid
2677 units; their length does not change and neither does the order of bytes
2678 within them. Such a rigid unit is called a @emph{section}. Assigning
2679 run-time addresses to sections is called @dfn{relocation}. It includes
2680 the task of adjusting mentions of object-file addresses so they refer to
2681 the proper run-time addresses.
2683 For the H8/300 and H8/500,
2684 and for the Renesas / SuperH SH,
2685 @command{@value{AS}} pads sections if needed to
2686 ensure they end on a word (sixteen bit) boundary.
2689 @cindex standard assembler sections
2690 An object file written by @command{@value{AS}} has at least three sections, any
2691 of which may be empty. These are named @dfn{text}, @dfn{data} and
2696 When it generates COFF or ELF output,
2698 @command{@value{AS}} can also generate whatever other named sections you specify
2699 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2700 If you do not use any directives that place output in the @samp{.text}
2701 or @samp{.data} sections, these sections still exist, but are empty.
2706 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2708 @command{@value{AS}} can also generate whatever other named sections you
2709 specify using the @samp{.space} and @samp{.subspace} directives. See
2710 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2711 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2712 assembler directives.
2715 Additionally, @command{@value{AS}} uses different names for the standard
2716 text, data, and bss sections when generating SOM output. Program text
2717 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2718 BSS into @samp{$BSS$}.
2722 Within the object file, the text section starts at address @code{0}, the
2723 data section follows, and the bss section follows the data section.
2726 When generating either SOM or ELF output files on the HPPA, the text
2727 section starts at address @code{0}, the data section at address
2728 @code{0x4000000}, and the bss section follows the data section.
2731 To let @code{@value{LD}} know which data changes when the sections are
2732 relocated, and how to change that data, @command{@value{AS}} also writes to the
2733 object file details of the relocation needed. To perform relocation
2734 @code{@value{LD}} must know, each time an address in the object
2738 Where in the object file is the beginning of this reference to
2741 How long (in bytes) is this reference?
2743 Which section does the address refer to? What is the numeric value of
2745 (@var{address}) @minus{} (@var{start-address of section})?
2748 Is the reference to an address ``Program-Counter relative''?
2751 @cindex addresses, format of
2752 @cindex section-relative addressing
2753 In fact, every address @command{@value{AS}} ever uses is expressed as
2755 (@var{section}) + (@var{offset into section})
2758 Further, most expressions @command{@value{AS}} computes have this section-relative
2761 (For some object formats, such as SOM for the HPPA, some expressions are
2762 symbol-relative instead.)
2765 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2766 @var{N} into section @var{secname}.''
2768 Apart from text, data and bss sections you need to know about the
2769 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2770 addresses in the absolute section remain unchanged. For example, address
2771 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2772 @code{@value{LD}}. Although the linker never arranges two partial programs'
2773 data sections with overlapping addresses after linking, @emph{by definition}
2774 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2775 part of a program is always the same address when the program is running as
2776 address @code{@{absolute@ 239@}} in any other part of the program.
2778 The idea of sections is extended to the @dfn{undefined} section. Any
2779 address whose section is unknown at assembly time is by definition
2780 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2781 Since numbers are always defined, the only way to generate an undefined
2782 address is to mention an undefined symbol. A reference to a named
2783 common block would be such a symbol: its value is unknown at assembly
2784 time so it has section @emph{undefined}.
2786 By analogy the word @emph{section} is used to describe groups of sections in
2787 the linked program. @code{@value{LD}} puts all partial programs' text
2788 sections in contiguous addresses in the linked program. It is
2789 customary to refer to the @emph{text section} of a program, meaning all
2790 the addresses of all partial programs' text sections. Likewise for
2791 data and bss sections.
2793 Some sections are manipulated by @code{@value{LD}}; others are invented for
2794 use of @command{@value{AS}} and have no meaning except during assembly.
2797 @section Linker Sections
2798 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2803 @cindex named sections
2804 @cindex sections, named
2805 @item named sections
2808 @cindex text section
2809 @cindex data section
2813 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2814 separate but equal sections. Anything you can say of one section is
2817 When the program is running, however, it is
2818 customary for the text section to be unalterable. The
2819 text section is often shared among processes: it contains
2820 instructions, constants and the like. The data section of a running
2821 program is usually alterable: for example, C variables would be stored
2822 in the data section.
2827 This section contains zeroed bytes when your program begins running. It
2828 is used to hold uninitialized variables or common storage. The length of
2829 each partial program's bss section is important, but because it starts
2830 out containing zeroed bytes there is no need to store explicit zero
2831 bytes in the object file. The bss section was invented to eliminate
2832 those explicit zeros from object files.
2834 @cindex absolute section
2835 @item absolute section
2836 Address 0 of this section is always ``relocated'' to runtime address 0.
2837 This is useful if you want to refer to an address that @code{@value{LD}} must
2838 not change when relocating. In this sense we speak of absolute
2839 addresses being ``unrelocatable'': they do not change during relocation.
2841 @cindex undefined section
2842 @item undefined section
2843 This ``section'' is a catch-all for address references to objects not in
2844 the preceding sections.
2845 @c FIXME: ref to some other doc on obj-file formats could go here.
2848 @cindex relocation example
2849 An idealized example of three relocatable sections follows.
2851 The example uses the traditional section names @samp{.text} and @samp{.data}.
2853 Memory addresses are on the horizontal axis.
2857 @c END TEXI2ROFF-KILL
2860 partial program # 1: |ttttt|dddd|00|
2867 partial program # 2: |TTT|DDD|000|
2870 +--+---+-----+--+----+---+-----+~~
2871 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2872 +--+---+-----+--+----+---+-----+~~
2874 addresses: 0 @dots{}
2881 \line{\it Partial program \#1: \hfil}
2882 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2883 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2885 \line{\it Partial program \#2: \hfil}
2886 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2887 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2889 \line{\it linked program: \hfil}
2890 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2891 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2892 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2893 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2895 \line{\it addresses: \hfil}
2899 @c END TEXI2ROFF-KILL
2902 @section Assembler Internal Sections
2904 @cindex internal assembler sections
2905 @cindex sections in messages, internal
2906 These sections are meant only for the internal use of @command{@value{AS}}. They
2907 have no meaning at run-time. You do not really need to know about these
2908 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2909 warning messages, so it might be helpful to have an idea of their
2910 meanings to @command{@value{AS}}. These sections are used to permit the
2911 value of every expression in your assembly language program to be a
2912 section-relative address.
2915 @cindex assembler internal logic error
2916 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2917 An internal assembler logic error has been found. This means there is a
2918 bug in the assembler.
2920 @cindex expr (internal section)
2922 The assembler stores complex expression internally as combinations of
2923 symbols. When it needs to represent an expression as a symbol, it puts
2924 it in the expr section.
2926 @c FIXME item transfer[t] vector preload
2927 @c FIXME item transfer[t] vector postload
2928 @c FIXME item register
2932 @section Sub-Sections
2934 @cindex numbered subsections
2935 @cindex grouping data
2941 fall into two sections: text and data.
2943 You may have separate groups of
2945 data in named sections
2949 data in named sections
2955 that you want to end up near to each other in the object file, even though they
2956 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2957 use @dfn{subsections} for this purpose. Within each section, there can be
2958 numbered subsections with values from 0 to 8192. Objects assembled into the
2959 same subsection go into the object file together with other objects in the same
2960 subsection. For example, a compiler might want to store constants in the text
2961 section, but might not want to have them interspersed with the program being
2962 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2963 section of code being output, and a @samp{.text 1} before each group of
2964 constants being output.
2966 Subsections are optional. If you do not use subsections, everything
2967 goes in subsection number zero.
2970 Each subsection is zero-padded up to a multiple of four bytes.
2971 (Subsections may be padded a different amount on different flavors
2972 of @command{@value{AS}}.)
2976 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2977 boundary (two bytes).
2978 The same is true on the Renesas SH.
2981 @c FIXME section padding (alignment)?
2982 @c Rich Pixley says padding here depends on target obj code format; that
2983 @c doesn't seem particularly useful to say without further elaboration,
2984 @c so for now I say nothing about it. If this is a generic BFD issue,
2985 @c these paragraphs might need to vanish from this manual, and be
2986 @c discussed in BFD chapter of binutils (or some such).
2989 On the AMD 29K family, no particular padding is added to section or
2990 subsection sizes; @value{AS} forces no alignment on this platform.
2994 Subsections appear in your object file in numeric order, lowest numbered
2995 to highest. (All this to be compatible with other people's assemblers.)
2996 The object file contains no representation of subsections; @code{@value{LD}} and
2997 other programs that manipulate object files see no trace of them.
2998 They just see all your text subsections as a text section, and all your
2999 data subsections as a data section.
3001 To specify which subsection you want subsequent statements assembled
3002 into, use a numeric argument to specify it, in a @samp{.text
3003 @var{expression}} or a @samp{.data @var{expression}} statement.
3006 When generating COFF output, you
3011 can also use an extra subsection
3012 argument with arbitrary named sections: @samp{.section @var{name},
3017 When generating ELF output, you
3022 can also use the @code{.subsection} directive (@pxref{SubSection})
3023 to specify a subsection: @samp{.subsection @var{expression}}.
3025 @var{Expression} should be an absolute expression.
3026 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
3027 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3028 begins in @code{text 0}. For instance:
3030 .text 0 # The default subsection is text 0 anyway.
3031 .ascii "This lives in the first text subsection. *"
3033 .ascii "But this lives in the second text subsection."
3035 .ascii "This lives in the data section,"
3036 .ascii "in the first data subsection."
3038 .ascii "This lives in the first text section,"
3039 .ascii "immediately following the asterisk (*)."
3042 Each section has a @dfn{location counter} incremented by one for every byte
3043 assembled into that section. Because subsections are merely a convenience
3044 restricted to @command{@value{AS}} there is no concept of a subsection location
3045 counter. There is no way to directly manipulate a location counter---but the
3046 @code{.align} directive changes it, and any label definition captures its
3047 current value. The location counter of the section where statements are being
3048 assembled is said to be the @dfn{active} location counter.
3051 @section bss Section
3054 @cindex common variable storage
3055 The bss section is used for local common variable storage.
3056 You may allocate address space in the bss section, but you may
3057 not dictate data to load into it before your program executes. When
3058 your program starts running, all the contents of the bss
3059 section are zeroed bytes.
3061 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3062 @ref{Lcomm,,@code{.lcomm}}.
3064 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3065 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
3068 When assembling for a target which supports multiple sections, such as ELF or
3069 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3070 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3071 section. Typically the section will only contain symbol definitions and
3072 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3079 Symbols are a central concept: the programmer uses symbols to name
3080 things, the linker uses symbols to link, and the debugger uses symbols
3084 @cindex debuggers, and symbol order
3085 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3086 the same order they were declared. This may break some debuggers.
3091 * Setting Symbols:: Giving Symbols Other Values
3092 * Symbol Names:: Symbol Names
3093 * Dot:: The Special Dot Symbol
3094 * Symbol Attributes:: Symbol Attributes
3101 A @dfn{label} is written as a symbol immediately followed by a colon
3102 @samp{:}. The symbol then represents the current value of the
3103 active location counter, and is, for example, a suitable instruction
3104 operand. You are warned if you use the same symbol to represent two
3105 different locations: the first definition overrides any other
3109 On the HPPA, the usual form for a label need not be immediately followed by a
3110 colon, but instead must start in column zero. Only one label may be defined on
3111 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3112 provides a special directive @code{.label} for defining labels more flexibly.
3115 @node Setting Symbols
3116 @section Giving Symbols Other Values
3118 @cindex assigning values to symbols
3119 @cindex symbol values, assigning
3120 A symbol can be given an arbitrary value by writing a symbol, followed
3121 by an equals sign @samp{=}, followed by an expression
3122 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3123 directive. @xref{Set,,@code{.set}}.
3126 @section Symbol Names
3128 @cindex symbol names
3129 @cindex names, symbol
3130 @ifclear SPECIAL-SYMS
3131 Symbol names begin with a letter or with one of @samp{._}. On most
3132 machines, you can also use @code{$} in symbol names; exceptions are
3133 noted in @ref{Machine Dependencies}. That character may be followed by any
3134 string of digits, letters, dollar signs (unless otherwise noted in
3135 @ref{Machine Dependencies}), and underscores.
3138 For the AMD 29K family, @samp{?} is also allowed in the
3139 body of a symbol name, though not at its beginning.
3144 Symbol names begin with a letter or with one of @samp{._}. On the
3145 Renesas SH or the H8/500, you can also use @code{$} in symbol names. That
3146 character may be followed by any string of digits, letters, dollar signs (save
3147 on the H8/300), and underscores.
3151 Case of letters is significant: @code{foo} is a different symbol name
3154 Each symbol has exactly one name. Each name in an assembly language program
3155 refers to exactly one symbol. You may use that symbol name any number of times
3158 @subheading Local Symbol Names
3160 @cindex local symbol names
3161 @cindex symbol names, local
3162 @cindex temporary symbol names
3163 @cindex symbol names, temporary
3164 Local symbols help compilers and programmers use names temporarily.
3165 They create symbols which are guaranteed to be unique over the entire scope of
3166 the input source code and which can be referred to by a simple notation.
3167 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3168 represents any positive integer). To refer to the most recent previous
3169 definition of that symbol write @samp{@b{N}b}, using the same number as when
3170 you defined the label. To refer to the next definition of a local label, write
3171 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3174 There is no restriction on how you can use these labels, and you can reuse them
3175 too. So that it is possible to repeatedly define the same local label (using
3176 the same number @samp{@b{N}}), although you can only refer to the most recently
3177 defined local label of that number (for a backwards reference) or the next
3178 definition of a specific local label for a forward reference. It is also worth
3179 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3180 implemented in a slightly more efficient manner than the others.
3191 Which is the equivalent of:
3194 label_1: branch label_3
3195 label_2: branch label_1
3196 label_3: branch label_4
3197 label_4: branch label_3
3200 Local symbol names are only a notational device. They are immediately
3201 transformed into more conventional symbol names before the assembler uses them.
3202 The symbol names stored in the symbol table, appearing in error messages and
3203 optionally emitted to the object file. The names are constructed using these
3208 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3209 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3210 used for symbols you are never intended to see. If you use the
3211 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3212 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3213 you may use them in debugging.
3216 This is the number that was used in the local label definition. So if the
3217 label is written @samp{55:} then the number is @samp{55}.
3220 This unusual character is included so you do not accidentally invent a symbol
3221 of the same name. The character has ASCII value of @samp{\002} (control-B).
3223 @item @emph{ordinal number}
3224 This is a serial number to keep the labels distinct. The first definition of
3225 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3226 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3227 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3230 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3231 @code{3:} is named @code{L3@kbd{C-B}44}.
3233 @subheading Dollar Local Labels
3234 @cindex dollar local symbols
3236 @code{@value{AS}} also supports an even more local form of local labels called
3237 dollar labels. These labels go out of scope (ie they become undefined) as soon
3238 as a non-local label is defined. Thus they remain valid for only a small
3239 region of the input source code. Normal local labels, by contrast, remain in
3240 scope for the entire file, or until they are redefined by another occurrence of
3241 the same local label.
3243 Dollar labels are defined in exactly the same way as ordinary local labels,
3244 except that instead of being terminated by a colon, they are terminated by a
3245 dollar sign. eg @samp{@b{55$}}.
3247 They can also be distinguished from ordinary local labels by their transformed
3248 name which uses ASCII character @samp{\001} (control-A) as the magic character
3249 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3250 is named @samp{L6@kbd{C-A}5}.
3253 @section The Special Dot Symbol
3255 @cindex dot (symbol)
3256 @cindex @code{.} (symbol)
3257 @cindex current address
3258 @cindex location counter
3259 The special symbol @samp{.} refers to the current address that
3260 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3261 .long .} defines @code{melvin} to contain its own address.
3262 Assigning a value to @code{.} is treated the same as a @code{.org}
3263 directive. Thus, the expression @samp{.=.+4} is the same as saying
3264 @ifclear no-space-dir
3273 @node Symbol Attributes
3274 @section Symbol Attributes
3276 @cindex symbol attributes
3277 @cindex attributes, symbol
3278 Every symbol has, as well as its name, the attributes ``Value'' and
3279 ``Type''. Depending on output format, symbols can also have auxiliary
3282 The detailed definitions are in @file{a.out.h}.
3285 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3286 all these attributes, and probably won't warn you. This makes the
3287 symbol an externally defined symbol, which is generally what you
3291 * Symbol Value:: Value
3292 * Symbol Type:: Type
3295 * a.out Symbols:: Symbol Attributes: @code{a.out}
3299 * a.out Symbols:: Symbol Attributes: @code{a.out}
3302 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3307 * COFF Symbols:: Symbol Attributes for COFF
3310 * SOM Symbols:: Symbol Attributes for SOM
3317 @cindex value of a symbol
3318 @cindex symbol value
3319 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3320 location in the text, data, bss or absolute sections the value is the
3321 number of addresses from the start of that section to the label.
3322 Naturally for text, data and bss sections the value of a symbol changes
3323 as @code{@value{LD}} changes section base addresses during linking. Absolute
3324 symbols' values do not change during linking: that is why they are
3327 The value of an undefined symbol is treated in a special way. If it is
3328 0 then the symbol is not defined in this assembler source file, and
3329 @code{@value{LD}} tries to determine its value from other files linked into the
3330 same program. You make this kind of symbol simply by mentioning a symbol
3331 name without defining it. A non-zero value represents a @code{.comm}
3332 common declaration. The value is how much common storage to reserve, in
3333 bytes (addresses). The symbol refers to the first address of the
3339 @cindex type of a symbol
3341 The type attribute of a symbol contains relocation (section)
3342 information, any flag settings indicating that a symbol is external, and
3343 (optionally), other information for linkers and debuggers. The exact
3344 format depends on the object-code output format in use.
3349 @c The following avoids a "widow" subsection title. @group would be
3350 @c better if it were available outside examples.
3353 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3355 @cindex @code{b.out} symbol attributes
3356 @cindex symbol attributes, @code{b.out}
3357 These symbol attributes appear only when @command{@value{AS}} is configured for
3358 one of the Berkeley-descended object output formats---@code{a.out} or
3364 @subsection Symbol Attributes: @code{a.out}
3366 @cindex @code{a.out} symbol attributes
3367 @cindex symbol attributes, @code{a.out}
3373 @subsection Symbol Attributes: @code{a.out}
3375 @cindex @code{a.out} symbol attributes
3376 @cindex symbol attributes, @code{a.out}
3380 * Symbol Desc:: Descriptor
3381 * Symbol Other:: Other
3385 @subsubsection Descriptor
3387 @cindex descriptor, of @code{a.out} symbol
3388 This is an arbitrary 16-bit value. You may establish a symbol's
3389 descriptor value by using a @code{.desc} statement
3390 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3391 @command{@value{AS}}.
3394 @subsubsection Other
3396 @cindex other attribute, of @code{a.out} symbol
3397 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3402 @subsection Symbol Attributes for COFF
3404 @cindex COFF symbol attributes
3405 @cindex symbol attributes, COFF
3407 The COFF format supports a multitude of auxiliary symbol attributes;
3408 like the primary symbol attributes, they are set between @code{.def} and
3409 @code{.endef} directives.
3411 @subsubsection Primary Attributes
3413 @cindex primary attributes, COFF symbols
3414 The symbol name is set with @code{.def}; the value and type,
3415 respectively, with @code{.val} and @code{.type}.
3417 @subsubsection Auxiliary Attributes
3419 @cindex auxiliary attributes, COFF symbols
3420 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3421 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3422 table information for COFF.
3427 @subsection Symbol Attributes for SOM
3429 @cindex SOM symbol attributes
3430 @cindex symbol attributes, SOM
3432 The SOM format for the HPPA supports a multitude of symbol attributes set with
3433 the @code{.EXPORT} and @code{.IMPORT} directives.
3435 The attributes are described in @cite{HP9000 Series 800 Assembly
3436 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3437 @code{EXPORT} assembler directive documentation.
3441 @chapter Expressions
3445 @cindex numeric values
3446 An @dfn{expression} specifies an address or numeric value.
3447 Whitespace may precede and/or follow an expression.
3449 The result of an expression must be an absolute number, or else an offset into
3450 a particular section. If an expression is not absolute, and there is not
3451 enough information when @command{@value{AS}} sees the expression to know its
3452 section, a second pass over the source program might be necessary to interpret
3453 the expression---but the second pass is currently not implemented.
3454 @command{@value{AS}} aborts with an error message in this situation.
3457 * Empty Exprs:: Empty Expressions
3458 * Integer Exprs:: Integer Expressions
3462 @section Empty Expressions
3464 @cindex empty expressions
3465 @cindex expressions, empty
3466 An empty expression has no value: it is just whitespace or null.
3467 Wherever an absolute expression is required, you may omit the
3468 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3469 is compatible with other assemblers.
3472 @section Integer Expressions
3474 @cindex integer expressions
3475 @cindex expressions, integer
3476 An @dfn{integer expression} is one or more @emph{arguments} delimited
3477 by @emph{operators}.
3480 * Arguments:: Arguments
3481 * Operators:: Operators
3482 * Prefix Ops:: Prefix Operators
3483 * Infix Ops:: Infix Operators
3487 @subsection Arguments
3489 @cindex expression arguments
3490 @cindex arguments in expressions
3491 @cindex operands in expressions
3492 @cindex arithmetic operands
3493 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3494 contexts arguments are sometimes called ``arithmetic operands''. In
3495 this manual, to avoid confusing them with the ``instruction operands'' of
3496 the machine language, we use the term ``argument'' to refer to parts of
3497 expressions only, reserving the word ``operand'' to refer only to machine
3498 instruction operands.
3500 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3501 @var{section} is one of text, data, bss, absolute,
3502 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3505 Numbers are usually integers.
3507 A number can be a flonum or bignum. In this case, you are warned
3508 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3509 these 32 bits are an integer. You may write integer-manipulating
3510 instructions that act on exotic constants, compatible with other
3513 @cindex subexpressions
3514 Subexpressions are a left parenthesis @samp{(} followed by an integer
3515 expression, followed by a right parenthesis @samp{)}; or a prefix
3516 operator followed by an argument.
3519 @subsection Operators
3521 @cindex operators, in expressions
3522 @cindex arithmetic functions
3523 @cindex functions, in expressions
3524 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3525 operators are followed by an argument. Infix operators appear
3526 between their arguments. Operators may be preceded and/or followed by
3530 @subsection Prefix Operator
3532 @cindex prefix operators
3533 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3534 one argument, which must be absolute.
3536 @c the tex/end tex stuff surrounding this small table is meant to make
3537 @c it align, on the printed page, with the similar table in the next
3538 @c section (which is inside an enumerate).
3540 \global\advance\leftskip by \itemindent
3545 @dfn{Negation}. Two's complement negation.
3547 @dfn{Complementation}. Bitwise not.
3551 \global\advance\leftskip by -\itemindent
3555 @subsection Infix Operators
3557 @cindex infix operators
3558 @cindex operators, permitted arguments
3559 @dfn{Infix operators} take two arguments, one on either side. Operators
3560 have precedence, but operations with equal precedence are performed left
3561 to right. Apart from @code{+} or @option{-}, both arguments must be
3562 absolute, and the result is absolute.
3565 @cindex operator precedence
3566 @cindex precedence of operators
3573 @dfn{Multiplication}.
3576 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3583 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3587 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3591 Intermediate precedence
3596 @dfn{Bitwise Inclusive Or}.
3602 @dfn{Bitwise Exclusive Or}.
3605 @dfn{Bitwise Or Not}.
3612 @cindex addition, permitted arguments
3613 @cindex plus, permitted arguments
3614 @cindex arguments for addition
3616 @dfn{Addition}. If either argument is absolute, the result has the section of
3617 the other argument. You may not add together arguments from different
3620 @cindex subtraction, permitted arguments
3621 @cindex minus, permitted arguments
3622 @cindex arguments for subtraction
3624 @dfn{Subtraction}. If the right argument is absolute, the
3625 result has the section of the left argument.
3626 If both arguments are in the same section, the result is absolute.
3627 You may not subtract arguments from different sections.
3628 @c FIXME is there still something useful to say about undefined - undefined ?
3630 @cindex comparison expressions
3631 @cindex expressions, comparison
3635 @dfn{Is Not Equal To}
3639 @dfn{Is Greater Than}
3641 @dfn{Is Greater Than Or Equal To}
3643 @dfn{Is Less Than Or Equal To}
3645 The comparison operators can be used as infix operators. A true results has a
3646 value of -1 whereas a false result has a value of 0. Note, these operators
3647 perform signed comparisons.
3650 @item Lowest Precedence
3659 These two logical operations can be used to combine the results of sub
3660 expressions. Note, unlike the comparison operators a true result returns a
3661 value of 1 but a false results does still return 0. Also note that the logical
3662 or operator has a slightly lower precedence than logical and.
3667 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3668 address; you can only have a defined section in one of the two arguments.
3671 @chapter Assembler Directives
3673 @cindex directives, machine independent
3674 @cindex pseudo-ops, machine independent
3675 @cindex machine independent directives
3676 All assembler directives have names that begin with a period (@samp{.}).
3677 The rest of the name is letters, usually in lower case.
3679 This chapter discusses directives that are available regardless of the
3680 target machine configuration for the @sc{gnu} assembler.
3682 Some machine configurations provide additional directives.
3683 @xref{Machine Dependencies}.
3686 @ifset machine-directives
3687 @xref{Machine Dependencies} for additional directives.
3692 * Abort:: @code{.abort}
3694 * ABORT:: @code{.ABORT}
3697 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3698 * Altmacro:: @code{.altmacro}
3699 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3700 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3701 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3702 * Byte:: @code{.byte @var{expressions}}
3703 * Comm:: @code{.comm @var{symbol} , @var{length} }
3705 * CFI directives:: @code{.cfi_startproc}, @code{.cfi_endproc}, etc.
3707 * Data:: @code{.data @var{subsection}}
3709 * Def:: @code{.def @var{name}}
3712 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3718 * Double:: @code{.double @var{flonums}}
3719 * Eject:: @code{.eject}
3720 * Else:: @code{.else}
3721 * Elseif:: @code{.elseif}
3724 * Endef:: @code{.endef}
3727 * Endfunc:: @code{.endfunc}
3728 * Endif:: @code{.endif}
3729 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3730 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3732 * Error:: @code{.error @var{string}}
3733 * Exitm:: @code{.exitm}
3734 * Extern:: @code{.extern}
3735 * Fail:: @code{.fail}
3736 @ifclear no-file-dir
3737 * File:: @code{.file @var{string}}
3740 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3741 * Float:: @code{.float @var{flonums}}
3742 * Func:: @code{.func}
3743 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3745 * Hidden:: @code{.hidden @var{names}}
3748 * hword:: @code{.hword @var{expressions}}
3749 * Ident:: @code{.ident}
3750 * If:: @code{.if @var{absolute expression}}
3751 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3752 * Include:: @code{.include "@var{file}"}
3753 * Int:: @code{.int @var{expressions}}
3755 * Internal:: @code{.internal @var{names}}
3758 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3759 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3760 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3761 * Lflags:: @code{.lflags}
3762 @ifclear no-line-dir
3763 * Line:: @code{.line @var{line-number}}
3766 * Ln:: @code{.ln @var{line-number}}
3767 * Linkonce:: @code{.linkonce [@var{type}]}
3768 * List:: @code{.list}
3769 * Long:: @code{.long @var{expressions}}
3771 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3774 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3775 * MRI:: @code{.mri @var{val}}
3776 * Noaltmacro:: @code{.noaltmacro}
3777 * Nolist:: @code{.nolist}
3778 * Octa:: @code{.octa @var{bignums}}
3779 * Org:: @code{.org @var{new-lc} , @var{fill}}
3780 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3782 * PopSection:: @code{.popsection}
3783 * Previous:: @code{.previous}
3786 * Print:: @code{.print @var{string}}
3788 * Protected:: @code{.protected @var{names}}
3791 * Psize:: @code{.psize @var{lines}, @var{columns}}
3792 * Purgem:: @code{.purgem @var{name}}
3794 * PushSection:: @code{.pushsection @var{name}}
3797 * Quad:: @code{.quad @var{bignums}}
3798 * Rept:: @code{.rept @var{count}}
3799 * Sbttl:: @code{.sbttl "@var{subheading}"}
3801 * Scl:: @code{.scl @var{class}}
3804 * Section:: @code{.section @var{name}}
3807 * Set:: @code{.set @var{symbol}, @var{expression}}
3808 * Short:: @code{.short @var{expressions}}
3809 * Single:: @code{.single @var{flonums}}
3811 * Size:: @code{.size [@var{name} , @var{expression}]}
3814 * Skip:: @code{.skip @var{size} , @var{fill}}
3815 * Sleb128:: @code{.sleb128 @var{expressions}}
3816 * Space:: @code{.space @var{size} , @var{fill}}
3818 * Stab:: @code{.stabd, .stabn, .stabs}
3821 * String:: @code{.string "@var{str}"}
3822 * Struct:: @code{.struct @var{expression}}
3824 * SubSection:: @code{.subsection}
3825 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3829 * Tag:: @code{.tag @var{structname}}
3832 * Text:: @code{.text @var{subsection}}
3833 * Title:: @code{.title "@var{heading}"}
3835 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3838 * Uleb128:: @code{.uleb128 @var{expressions}}
3840 * Val:: @code{.val @var{addr}}
3844 * Version:: @code{.version "@var{string}"}
3845 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3846 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3849 * Warning:: @code{.warning @var{string}}
3850 * Weak:: @code{.weak @var{names}}
3851 * Word:: @code{.word @var{expressions}}
3852 * Deprecated:: Deprecated Directives
3856 @section @code{.abort}
3858 @cindex @code{abort} directive
3859 @cindex stopping the assembly
3860 This directive stops the assembly immediately. It is for
3861 compatibility with other assemblers. The original idea was that the
3862 assembly language source would be piped into the assembler. If the sender
3863 of the source quit, it could use this directive tells @command{@value{AS}} to
3864 quit also. One day @code{.abort} will not be supported.
3868 @section @code{.ABORT}
3870 @cindex @code{ABORT} directive
3871 When producing COFF output, @command{@value{AS}} accepts this directive as a
3872 synonym for @samp{.abort}.
3875 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3881 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3883 @cindex padding the location counter
3884 @cindex @code{align} directive
3885 Pad the location counter (in the current subsection) to a particular storage
3886 boundary. The first expression (which must be absolute) is the alignment
3887 required, as described below.
3889 The second expression (also absolute) gives the fill value to be stored in the
3890 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3891 padding bytes are normally zero. However, on some systems, if the section is
3892 marked as containing code and the fill value is omitted, the space is filled
3893 with no-op instructions.
3895 The third expression is also absolute, and is also optional. If it is present,
3896 it is the maximum number of bytes that should be skipped by this alignment
3897 directive. If doing the alignment would require skipping more bytes than the
3898 specified maximum, then the alignment is not done at all. You can omit the
3899 fill value (the second argument) entirely by simply using two commas after the
3900 required alignment; this can be useful if you want the alignment to be filled
3901 with no-op instructions when appropriate.
3903 The way the required alignment is specified varies from system to system.
3904 For the a29k, arc, hppa, i386 using ELF, i860, iq2000, m68k, m88k, or32,
3905 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
3906 alignment request in bytes. For example @samp{.align 8} advances
3907 the location counter until it is a multiple of 8. If the location counter
3908 is already a multiple of 8, no change is needed. For the tic54x, the
3909 first expression is the alignment request in words.
3911 For other systems, including the i386 using a.out format, and the arm and
3912 strongarm, it is the
3913 number of low-order zero bits the location counter must have after
3914 advancement. For example @samp{.align 3} advances the location
3915 counter until it a multiple of 8. If the location counter is already a
3916 multiple of 8, no change is needed.
3918 This inconsistency is due to the different behaviors of the various
3919 native assemblers for these systems which GAS must emulate.
3920 GAS also provides @code{.balign} and @code{.p2align} directives,
3921 described later, which have a consistent behavior across all
3922 architectures (but are specific to GAS).
3925 @section @code{.ascii "@var{string}"}@dots{}
3927 @cindex @code{ascii} directive
3928 @cindex string literals
3929 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3930 separated by commas. It assembles each string (with no automatic
3931 trailing zero byte) into consecutive addresses.
3934 @section @code{.asciz "@var{string}"}@dots{}
3936 @cindex @code{asciz} directive
3937 @cindex zero-terminated strings
3938 @cindex null-terminated strings
3939 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3940 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3943 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3945 @cindex padding the location counter given number of bytes
3946 @cindex @code{balign} directive
3947 Pad the location counter (in the current subsection) to a particular
3948 storage boundary. The first expression (which must be absolute) is the
3949 alignment request in bytes. For example @samp{.balign 8} advances
3950 the location counter until it is a multiple of 8. If the location counter
3951 is already a multiple of 8, no change is needed.
3953 The second expression (also absolute) gives the fill value to be stored in the
3954 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3955 padding bytes are normally zero. However, on some systems, if the section is
3956 marked as containing code and the fill value is omitted, the space is filled
3957 with no-op instructions.
3959 The third expression is also absolute, and is also optional. If it is present,
3960 it is the maximum number of bytes that should be skipped by this alignment
3961 directive. If doing the alignment would require skipping more bytes than the
3962 specified maximum, then the alignment is not done at all. You can omit the
3963 fill value (the second argument) entirely by simply using two commas after the
3964 required alignment; this can be useful if you want the alignment to be filled
3965 with no-op instructions when appropriate.
3967 @cindex @code{balignw} directive
3968 @cindex @code{balignl} directive
3969 The @code{.balignw} and @code{.balignl} directives are variants of the
3970 @code{.balign} directive. The @code{.balignw} directive treats the fill
3971 pattern as a two byte word value. The @code{.balignl} directives treats the
3972 fill pattern as a four byte longword value. For example, @code{.balignw
3973 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3974 filled in with the value 0x368d (the exact placement of the bytes depends upon
3975 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3979 @section @code{.byte @var{expressions}}
3981 @cindex @code{byte} directive
3982 @cindex integers, one byte
3983 @code{.byte} expects zero or more expressions, separated by commas.
3984 Each expression is assembled into the next byte.
3987 @section @code{.comm @var{symbol} , @var{length} }
3989 @cindex @code{comm} directive
3990 @cindex symbol, common
3991 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3992 common symbol in one object file may be merged with a defined or common symbol
3993 of the same name in another object file. If @code{@value{LD}} does not see a
3994 definition for the symbol--just one or more common symbols--then it will
3995 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3996 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3997 the same name, and they do not all have the same size, it will allocate space
3998 using the largest size.
4001 When using ELF, the @code{.comm} directive takes an optional third argument.
4002 This is the desired alignment of the symbol, specified as a byte boundary (for
4003 example, an alignment of 16 means that the least significant 4 bits of the
4004 address should be zero). The alignment must be an absolute expression, and it
4005 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
4006 for the common symbol, it will use the alignment when placing the symbol. If
4007 no alignment is specified, @command{@value{AS}} will set the alignment to the
4008 largest power of two less than or equal to the size of the symbol, up to a
4013 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4014 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4017 @node CFI directives
4018 @section @code{.cfi_startproc}
4019 @cindex @code{cfi_startproc} directive
4020 @code{.cfi_startproc} is used at the beginning of each function that
4021 should have an entry in @code{.eh_frame}. It initializes some internal
4022 data structures and emits architecture dependent initial CFI instructions.
4023 Don't forget to close the function by
4024 @code{.cfi_endproc}.
4026 @section @code{.cfi_endproc}
4027 @cindex @code{cfi_endproc} directive
4028 @code{.cfi_endproc} is used at the end of a function where it closes its
4029 unwind entry previously opened by
4030 @code{.cfi_startproc}. and emits it to @code{.eh_frame}.
4032 @section @code{.cfi_def_cfa @var{register}, @var{offset}}
4033 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4034 address from @var{register} and add @var{offset} to it}.
4036 @section @code{.cfi_def_cfa_register @var{register}}
4037 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4038 now on @var{register} will be used instead of the old one. Offset
4041 @section @code{.cfi_def_cfa_offset @var{offset}}
4042 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4043 remains the same, but @var{offset} is new. Note that it is the
4044 absolute offset that will be added to a defined register to compute
4047 @section @code{.cfi_adjust_cfa_offset @var{offset}}
4048 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4049 value that is added/substracted from the previous offset.
4051 @section @code{.cfi_offset @var{register}, @var{offset}}
4052 Previous value of @var{register} is saved at offset @var{offset} from
4055 @section @code{.cfi_rel_offset @var{register}, @var{offset}}
4056 Previous value of @var{register} is saved at offset @var{offset} from
4057 the current CFA register. This is transformed to @code{.cfi_offset}
4058 using the known displacement of the CFA register from the CFA.
4059 This is often easier to use, because the number will match the
4060 code it's annotating.
4062 @section @code{.cfi_window_save}
4063 SPARC register window has been saved.
4065 @section @code{.cfi_escape} @var{expression}[, @dots{}]
4066 Allows the user to add arbitrary bytes to the unwind info. One
4067 might use this to add OS-specific CFI opcodes, or generic CFI
4068 opcodes that GAS does not yet support.
4071 @section @code{.data @var{subsection}}
4073 @cindex @code{data} directive
4074 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4075 end of the data subsection numbered @var{subsection} (which is an
4076 absolute expression). If @var{subsection} is omitted, it defaults
4081 @section @code{.def @var{name}}
4083 @cindex @code{def} directive
4084 @cindex COFF symbols, debugging
4085 @cindex debugging COFF symbols
4086 Begin defining debugging information for a symbol @var{name}; the
4087 definition extends until the @code{.endef} directive is encountered.
4090 This directive is only observed when @command{@value{AS}} is configured for COFF
4091 format output; when producing @code{b.out}, @samp{.def} is recognized,
4098 @section @code{.desc @var{symbol}, @var{abs-expression}}
4100 @cindex @code{desc} directive
4101 @cindex COFF symbol descriptor
4102 @cindex symbol descriptor, COFF
4103 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4104 to the low 16 bits of an absolute expression.
4107 The @samp{.desc} directive is not available when @command{@value{AS}} is
4108 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4109 object format. For the sake of compatibility, @command{@value{AS}} accepts
4110 it, but produces no output, when configured for COFF.
4116 @section @code{.dim}
4118 @cindex @code{dim} directive
4119 @cindex COFF auxiliary symbol information
4120 @cindex auxiliary symbol information, COFF
4121 This directive is generated by compilers to include auxiliary debugging
4122 information in the symbol table. It is only permitted inside
4123 @code{.def}/@code{.endef} pairs.
4126 @samp{.dim} is only meaningful when generating COFF format output; when
4127 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4133 @section @code{.double @var{flonums}}
4135 @cindex @code{double} directive
4136 @cindex floating point numbers (double)
4137 @code{.double} expects zero or more flonums, separated by commas. It
4138 assembles floating point numbers.
4140 The exact kind of floating point numbers emitted depends on how
4141 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4145 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4146 in @sc{ieee} format.
4151 @section @code{.eject}
4153 @cindex @code{eject} directive
4154 @cindex new page, in listings
4155 @cindex page, in listings
4156 @cindex listing control: new page
4157 Force a page break at this point, when generating assembly listings.
4160 @section @code{.else}
4162 @cindex @code{else} directive
4163 @code{.else} is part of the @command{@value{AS}} support for conditional
4164 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
4165 of code to be assembled if the condition for the preceding @code{.if}
4169 @section @code{.elseif}
4171 @cindex @code{elseif} directive
4172 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4173 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
4174 @code{.if} block that would otherwise fill the entire @code{.else} section.
4177 @section @code{.end}
4179 @cindex @code{end} directive
4180 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4181 process anything in the file past the @code{.end} directive.
4185 @section @code{.endef}
4187 @cindex @code{endef} directive
4188 This directive flags the end of a symbol definition begun with
4192 @samp{.endef} is only meaningful when generating COFF format output; if
4193 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4194 directive but ignores it.
4199 @section @code{.endfunc}
4200 @cindex @code{endfunc} directive
4201 @code{.endfunc} marks the end of a function specified with @code{.func}.
4204 @section @code{.endif}
4206 @cindex @code{endif} directive
4207 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4208 it marks the end of a block of code that is only assembled
4209 conditionally. @xref{If,,@code{.if}}.
4212 @section @code{.equ @var{symbol}, @var{expression}}
4214 @cindex @code{equ} directive
4215 @cindex assigning values to symbols
4216 @cindex symbols, assigning values to
4217 This directive sets the value of @var{symbol} to @var{expression}.
4218 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
4221 The syntax for @code{equ} on the HPPA is
4222 @samp{@var{symbol} .equ @var{expression}}.
4226 @section @code{.equiv @var{symbol}, @var{expression}}
4227 @cindex @code{equiv} directive
4228 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4229 the assembler will signal an error if @var{symbol} is already defined. Note a
4230 symbol which has been referenced but not actually defined is considered to be
4233 Except for the contents of the error message, this is roughly equivalent to
4242 @section @code{.err}
4243 @cindex @code{err} directive
4244 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4245 message and, unless the @option{-Z} option was used, it will not generate an
4246 object file. This can be used to signal error an conditionally compiled code.
4249 @section @code{.error "@var{string}"}
4250 @cindex error directive
4252 Similarly to @code{.err}, this directive emits an error, but you can specify a
4253 string that will be emitted as the error message. If you don't specify the
4254 message, it defaults to @code{".error directive invoked in source file"}.
4255 @xref{Errors, ,Error and Warning Messages}.
4258 .error "This code has not been assembled and tested."
4262 @section @code{.exitm}
4263 Exit early from the current macro definition. @xref{Macro}.
4266 @section @code{.extern}
4268 @cindex @code{extern} directive
4269 @code{.extern} is accepted in the source program---for compatibility
4270 with other assemblers---but it is ignored. @command{@value{AS}} treats
4271 all undefined symbols as external.
4274 @section @code{.fail @var{expression}}
4276 @cindex @code{fail} directive
4277 Generates an error or a warning. If the value of the @var{expression} is 500
4278 or more, @command{@value{AS}} will print a warning message. If the value is less
4279 than 500, @command{@value{AS}} will print an error message. The message will
4280 include the value of @var{expression}. This can occasionally be useful inside
4281 complex nested macros or conditional assembly.
4283 @ifclear no-file-dir
4285 @section @code{.file @var{string}}
4287 @cindex @code{file} directive
4288 @cindex logical file name
4289 @cindex file name, logical
4290 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4291 file. @var{string} is the new file name. In general, the filename is
4292 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4293 to specify an empty file name, you must give the quotes--@code{""}. This
4294 statement may go away in future: it is only recognized to be compatible with
4295 old @command{@value{AS}} programs.
4297 In some configurations of @command{@value{AS}}, @code{.file} has already been
4298 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4303 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4305 @cindex @code{fill} directive
4306 @cindex writing patterns in memory
4307 @cindex patterns, writing in memory
4308 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4309 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4310 may be zero or more. @var{Size} may be zero or more, but if it is
4311 more than 8, then it is deemed to have the value 8, compatible with
4312 other people's assemblers. The contents of each @var{repeat} bytes
4313 is taken from an 8-byte number. The highest order 4 bytes are
4314 zero. The lowest order 4 bytes are @var{value} rendered in the
4315 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4316 Each @var{size} bytes in a repetition is taken from the lowest order
4317 @var{size} bytes of this number. Again, this bizarre behavior is
4318 compatible with other people's assemblers.
4320 @var{size} and @var{value} are optional.
4321 If the second comma and @var{value} are absent, @var{value} is
4322 assumed zero. If the first comma and following tokens are absent,
4323 @var{size} is assumed to be 1.
4326 @section @code{.float @var{flonums}}
4328 @cindex floating point numbers (single)
4329 @cindex @code{float} directive
4330 This directive assembles zero or more flonums, separated by commas. It
4331 has the same effect as @code{.single}.
4333 The exact kind of floating point numbers emitted depends on how
4334 @command{@value{AS}} is configured.
4335 @xref{Machine Dependencies}.
4339 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4340 in @sc{ieee} format.
4345 @section @code{.func @var{name}[,@var{label}]}
4346 @cindex @code{func} directive
4347 @code{.func} emits debugging information to denote function @var{name}, and
4348 is ignored unless the file is assembled with debugging enabled.
4349 Only @samp{--gstabs[+]} is currently supported.
4350 @var{label} is the entry point of the function and if omitted @var{name}
4351 prepended with the @samp{leading char} is used.
4352 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4353 All functions are currently defined to have @code{void} return type.
4354 The function must be terminated with @code{.endfunc}.
4357 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4359 @cindex @code{global} directive
4360 @cindex symbol, making visible to linker
4361 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4362 @var{symbol} in your partial program, its value is made available to
4363 other partial programs that are linked with it. Otherwise,
4364 @var{symbol} takes its attributes from a symbol of the same name
4365 from another file linked into the same program.
4367 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4368 compatibility with other assemblers.
4371 On the HPPA, @code{.global} is not always enough to make it accessible to other
4372 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4373 @xref{HPPA Directives,, HPPA Assembler Directives}.
4378 @section @code{.hidden @var{names}}
4380 @cindex @code{hidden} directive
4382 This is one of the ELF visibility directives. The other two are
4383 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4384 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4386 This directive overrides the named symbols default visibility (which is set by
4387 their binding: local, global or weak). The directive sets the visibility to
4388 @code{hidden} which means that the symbols are not visible to other components.
4389 Such symbols are always considered to be @code{protected} as well.
4393 @section @code{.hword @var{expressions}}
4395 @cindex @code{hword} directive
4396 @cindex integers, 16-bit
4397 @cindex numbers, 16-bit
4398 @cindex sixteen bit integers
4399 This expects zero or more @var{expressions}, and emits
4400 a 16 bit number for each.
4403 This directive is a synonym for @samp{.short}; depending on the target
4404 architecture, it may also be a synonym for @samp{.word}.
4408 This directive is a synonym for @samp{.short}.
4411 This directive is a synonym for both @samp{.short} and @samp{.word}.
4416 @section @code{.ident}
4418 @cindex @code{ident} directive
4419 This directive is used by some assemblers to place tags in object files.
4420 @command{@value{AS}} simply accepts the directive for source-file
4421 compatibility with such assemblers, but does not actually emit anything
4425 @section @code{.if @var{absolute expression}}
4427 @cindex conditional assembly
4428 @cindex @code{if} directive
4429 @code{.if} marks the beginning of a section of code which is only
4430 considered part of the source program being assembled if the argument
4431 (which must be an @var{absolute expression}) is non-zero. The end of
4432 the conditional section of code must be marked by @code{.endif}
4433 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4434 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4435 If you have several conditions to check, @code{.elseif} may be used to avoid
4436 nesting blocks if/else within each subsequent @code{.else} block.
4438 The following variants of @code{.if} are also supported:
4440 @cindex @code{ifdef} directive
4441 @item .ifdef @var{symbol}
4442 Assembles the following section of code if the specified @var{symbol}
4443 has been defined. Note a symbol which has been referenced but not yet defined
4444 is considered to be undefined.
4446 @cindex @code{ifc} directive
4447 @item .ifc @var{string1},@var{string2}
4448 Assembles the following section of code if the two strings are the same. The
4449 strings may be optionally quoted with single quotes. If they are not quoted,
4450 the first string stops at the first comma, and the second string stops at the
4451 end of the line. Strings which contain whitespace should be quoted. The
4452 string comparison is case sensitive.
4454 @cindex @code{ifeq} directive
4455 @item .ifeq @var{absolute expression}
4456 Assembles the following section of code if the argument is zero.
4458 @cindex @code{ifeqs} directive
4459 @item .ifeqs @var{string1},@var{string2}
4460 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4462 @cindex @code{ifge} directive
4463 @item .ifge @var{absolute expression}
4464 Assembles the following section of code if the argument is greater than or
4467 @cindex @code{ifgt} directive
4468 @item .ifgt @var{absolute expression}
4469 Assembles the following section of code if the argument is greater than zero.
4471 @cindex @code{ifle} directive
4472 @item .ifle @var{absolute expression}
4473 Assembles the following section of code if the argument is less than or equal
4476 @cindex @code{iflt} directive
4477 @item .iflt @var{absolute expression}
4478 Assembles the following section of code if the argument is less than zero.
4480 @cindex @code{ifnc} directive
4481 @item .ifnc @var{string1},@var{string2}.
4482 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4483 following section of code if the two strings are not the same.
4485 @cindex @code{ifndef} directive
4486 @cindex @code{ifnotdef} directive
4487 @item .ifndef @var{symbol}
4488 @itemx .ifnotdef @var{symbol}
4489 Assembles the following section of code if the specified @var{symbol}
4490 has not been defined. Both spelling variants are equivalent. Note a symbol
4491 which has been referenced but not yet defined is considered to be undefined.
4493 @cindex @code{ifne} directive
4494 @item .ifne @var{absolute expression}
4495 Assembles the following section of code if the argument is not equal to zero
4496 (in other words, this is equivalent to @code{.if}).
4498 @cindex @code{ifnes} directive
4499 @item .ifnes @var{string1},@var{string2}
4500 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4501 following section of code if the two strings are not the same.
4505 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4507 @cindex @code{incbin} directive
4508 @cindex binary files, including
4509 The @code{incbin} directive includes @var{file} verbatim at the current
4510 location. You can control the search paths used with the @samp{-I} command-line
4511 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4514 The @var{skip} argument skips a number of bytes from the start of the
4515 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4516 read. Note that the data is not aligned in any way, so it is the user's
4517 responsibility to make sure that proper alignment is provided both before and
4518 after the @code{incbin} directive.
4521 @section @code{.include "@var{file}"}
4523 @cindex @code{include} directive
4524 @cindex supporting files, including
4525 @cindex files, including
4526 This directive provides a way to include supporting files at specified
4527 points in your source program. The code from @var{file} is assembled as
4528 if it followed the point of the @code{.include}; when the end of the
4529 included file is reached, assembly of the original file continues. You
4530 can control the search paths used with the @samp{-I} command-line option
4531 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4535 @section @code{.int @var{expressions}}
4537 @cindex @code{int} directive
4538 @cindex integers, 32-bit
4539 Expect zero or more @var{expressions}, of any section, separated by commas.
4540 For each expression, emit a number that, at run time, is the value of that
4541 expression. The byte order and bit size of the number depends on what kind
4542 of target the assembly is for.
4546 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4547 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
4554 @section @code{.internal @var{names}}
4556 @cindex @code{internal} directive
4558 This is one of the ELF visibility directives. The other two are
4559 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4560 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4562 This directive overrides the named symbols default visibility (which is set by
4563 their binding: local, global or weak). The directive sets the visibility to
4564 @code{internal} which means that the symbols are considered to be @code{hidden}
4565 (i.e., not visible to other components), and that some extra, processor specific
4566 processing must also be performed upon the symbols as well.
4570 @section @code{.irp @var{symbol},@var{values}}@dots{}
4572 @cindex @code{irp} directive
4573 Evaluate a sequence of statements assigning different values to @var{symbol}.
4574 The sequence of statements starts at the @code{.irp} directive, and is
4575 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4576 set to @var{value}, and the sequence of statements is assembled. If no
4577 @var{value} is listed, the sequence of statements is assembled once, with
4578 @var{symbol} set to the null string. To refer to @var{symbol} within the
4579 sequence of statements, use @var{\symbol}.
4581 For example, assembling
4589 is equivalent to assembling
4598 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4600 @cindex @code{irpc} directive
4601 Evaluate a sequence of statements assigning different values to @var{symbol}.
4602 The sequence of statements starts at the @code{.irpc} directive, and is
4603 terminated by an @code{.endr} directive. For each character in @var{value},
4604 @var{symbol} is set to the character, and the sequence of statements is
4605 assembled. If no @var{value} is listed, the sequence of statements is
4606 assembled once, with @var{symbol} set to the null string. To refer to
4607 @var{symbol} within the sequence of statements, use @var{\symbol}.
4609 For example, assembling
4617 is equivalent to assembling
4626 @section @code{.lcomm @var{symbol} , @var{length}}
4628 @cindex @code{lcomm} directive
4629 @cindex local common symbols
4630 @cindex symbols, local common
4631 Reserve @var{length} (an absolute expression) bytes for a local common
4632 denoted by @var{symbol}. The section and value of @var{symbol} are
4633 those of the new local common. The addresses are allocated in the bss
4634 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4635 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4636 not visible to @code{@value{LD}}.
4639 Some targets permit a third argument to be used with @code{.lcomm}. This
4640 argument specifies the desired alignment of the symbol in the bss section.
4644 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4645 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4649 @section @code{.lflags}
4651 @cindex @code{lflags} directive (ignored)
4652 @command{@value{AS}} accepts this directive, for compatibility with other
4653 assemblers, but ignores it.
4655 @ifclear no-line-dir
4657 @section @code{.line @var{line-number}}
4659 @cindex @code{line} directive
4663 @section @code{.ln @var{line-number}}
4665 @cindex @code{ln} directive
4667 @cindex logical line number
4669 Change the logical line number. @var{line-number} must be an absolute
4670 expression. The next line has that logical line number. Therefore any other
4671 statements on the current line (after a statement separator character) are
4672 reported as on logical line number @var{line-number} @minus{} 1. One day
4673 @command{@value{AS}} will no longer support this directive: it is recognized only
4674 for compatibility with existing assembler programs.
4678 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4679 not available; use the synonym @code{.ln} in that context.
4684 @ifclear no-line-dir
4685 Even though this is a directive associated with the @code{a.out} or
4686 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4687 when producing COFF output, and treats @samp{.line} as though it
4688 were the COFF @samp{.ln} @emph{if} it is found outside a
4689 @code{.def}/@code{.endef} pair.
4691 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4692 used by compilers to generate auxiliary symbol information for
4697 @section @code{.linkonce [@var{type}]}
4699 @cindex @code{linkonce} directive
4700 @cindex common sections
4701 Mark the current section so that the linker only includes a single copy of it.
4702 This may be used to include the same section in several different object files,
4703 but ensure that the linker will only include it once in the final output file.
4704 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4705 Duplicate sections are detected based on the section name, so it should be
4708 This directive is only supported by a few object file formats; as of this
4709 writing, the only object file format which supports it is the Portable
4710 Executable format used on Windows NT.
4712 The @var{type} argument is optional. If specified, it must be one of the
4713 following strings. For example:
4717 Not all types may be supported on all object file formats.
4721 Silently discard duplicate sections. This is the default.
4724 Warn if there are duplicate sections, but still keep only one copy.
4727 Warn if any of the duplicates have different sizes.
4730 Warn if any of the duplicates do not have exactly the same contents.
4734 @section @code{.ln @var{line-number}}
4736 @cindex @code{ln} directive
4737 @ifclear no-line-dir
4738 @samp{.ln} is a synonym for @samp{.line}.
4741 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4742 must be an absolute expression. The next line has that logical
4743 line number, so any other statements on the current line (after a
4744 statement separator character @code{;}) are reported as on logical
4745 line number @var{line-number} @minus{} 1.
4748 This directive is accepted, but ignored, when @command{@value{AS}} is
4749 configured for @code{b.out}; its effect is only associated with COFF
4755 @section @code{.mri @var{val}}
4757 @cindex @code{mri} directive
4758 @cindex MRI mode, temporarily
4759 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4760 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4761 affects code assembled until the next @code{.mri} directive, or until the end
4762 of the file. @xref{M, MRI mode, MRI mode}.
4765 @section @code{.list}
4767 @cindex @code{list} directive
4768 @cindex listing control, turning on
4769 Control (in conjunction with the @code{.nolist} directive) whether or
4770 not assembly listings are generated. These two directives maintain an
4771 internal counter (which is zero initially). @code{.list} increments the
4772 counter, and @code{.nolist} decrements it. Assembly listings are
4773 generated whenever the counter is greater than zero.
4775 By default, listings are disabled. When you enable them (with the
4776 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4777 the initial value of the listing counter is one.
4780 @section @code{.long @var{expressions}}
4782 @cindex @code{long} directive
4783 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4786 @c no one seems to know what this is for or whether this description is
4787 @c what it really ought to do
4789 @section @code{.lsym @var{symbol}, @var{expression}}
4791 @cindex @code{lsym} directive
4792 @cindex symbol, not referenced in assembly
4793 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4794 the hash table, ensuring it cannot be referenced by name during the
4795 rest of the assembly. This sets the attributes of the symbol to be
4796 the same as the expression value:
4798 @var{other} = @var{descriptor} = 0
4799 @var{type} = @r{(section of @var{expression})}
4800 @var{value} = @var{expression}
4803 The new symbol is not flagged as external.
4807 @section @code{.macro}
4810 The commands @code{.macro} and @code{.endm} allow you to define macros that
4811 generate assembly output. For example, this definition specifies a macro
4812 @code{sum} that puts a sequence of numbers into memory:
4815 .macro sum from=0, to=5
4824 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4836 @item .macro @var{macname}
4837 @itemx .macro @var{macname} @var{macargs} @dots{}
4838 @cindex @code{macro} directive
4839 Begin the definition of a macro called @var{macname}. If your macro
4840 definition requires arguments, specify their names after the macro name,
4841 separated by commas or spaces. You can supply a default value for any
4842 macro argument by following the name with @samp{=@var{deflt}}. You
4843 cannot define two macros with the same @var{macname} unless it has been
4844 subject to the @code{.purgem} directive (@xref{Purgem}.) between the two
4845 definitions. For example, these are all valid @code{.macro} statements:
4849 Begin the definition of a macro called @code{comm}, which takes no
4852 @item .macro plus1 p, p1
4853 @itemx .macro plus1 p p1
4854 Either statement begins the definition of a macro called @code{plus1},
4855 which takes two arguments; within the macro definition, write
4856 @samp{\p} or @samp{\p1} to evaluate the arguments.
4858 @item .macro reserve_str p1=0 p2
4859 Begin the definition of a macro called @code{reserve_str}, with two
4860 arguments. The first argument has a default value, but not the second.
4861 After the definition is complete, you can call the macro either as
4862 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4863 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4864 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4865 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4868 When you call a macro, you can specify the argument values either by
4869 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4870 @samp{sum to=17, from=9}.
4873 @cindex @code{endm} directive
4874 Mark the end of a macro definition.
4877 @cindex @code{exitm} directive
4878 Exit early from the current macro definition.
4880 @cindex number of macros executed
4881 @cindex macros, count executed
4883 @command{@value{AS}} maintains a counter of how many macros it has
4884 executed in this pseudo-variable; you can copy that number to your
4885 output with @samp{\@@}, but @emph{only within a macro definition}.
4887 @item LOCAL @var{name} [ , @dots{} ]
4888 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4889 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
4890 @xref{Altmacro,,@code{.altmacro}}.
4894 @section @code{.altmacro}
4895 Enable alternate macro mode, enabling:
4898 @item LOCAL @var{name} [ , @dots{} ]
4899 One additional directive, @code{LOCAL}, is available. It is used to
4900 generate a string replacement for each of the @var{name} arguments, and
4901 replace any instances of @var{name} in each macro expansion. The
4902 replacement string is unique in the assembly, and different for each
4903 separate macro expansion. @code{LOCAL} allows you to write macros that
4904 define symbols, without fear of conflict between separate macro expansions.
4906 @item String delimiters
4907 You can write strings delimited in these other ways besides
4908 @code{"@var{string}"}:
4911 @item '@var{string}'
4912 You can delimit strings with single-quote charaters.
4914 @item <@var{string}>
4915 You can delimit strings with matching angle brackets.
4918 @item single-character string escape
4919 To include any single character literally in a string (even if the
4920 character would otherwise have some special meaning), you can prefix the
4921 character with @samp{!} (an exclamation mark). For example, you can
4922 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4924 @item Expression results as strings
4925 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4926 and use the result as a string.
4930 @section @code{.noaltmacro}
4931 Disable alternate macro mode. @ref{Altmacro}
4934 @section @code{.nolist}
4936 @cindex @code{nolist} directive
4937 @cindex listing control, turning off
4938 Control (in conjunction with the @code{.list} directive) whether or
4939 not assembly listings are generated. These two directives maintain an
4940 internal counter (which is zero initially). @code{.list} increments the
4941 counter, and @code{.nolist} decrements it. Assembly listings are
4942 generated whenever the counter is greater than zero.
4945 @section @code{.octa @var{bignums}}
4947 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4948 @cindex @code{octa} directive
4949 @cindex integer, 16-byte
4950 @cindex sixteen byte integer
4951 This directive expects zero or more bignums, separated by commas. For each
4952 bignum, it emits a 16-byte integer.
4954 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4955 hence @emph{octa}-word for 16 bytes.
4958 @section @code{.org @var{new-lc} , @var{fill}}
4960 @cindex @code{org} directive
4961 @cindex location counter, advancing
4962 @cindex advancing location counter
4963 @cindex current address, advancing
4964 Advance the location counter of the current section to
4965 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4966 expression with the same section as the current subsection. That is,
4967 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4968 wrong section, the @code{.org} directive is ignored. To be compatible
4969 with former assemblers, if the section of @var{new-lc} is absolute,
4970 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4971 is the same as the current subsection.
4973 @code{.org} may only increase the location counter, or leave it
4974 unchanged; you cannot use @code{.org} to move the location counter
4977 @c double negative used below "not undefined" because this is a specific
4978 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4979 @c section. doc@cygnus.com 18feb91
4980 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4981 may not be undefined. If you really detest this restriction we eagerly await
4982 a chance to share your improved assembler.
4984 Beware that the origin is relative to the start of the section, not
4985 to the start of the subsection. This is compatible with other
4986 people's assemblers.
4988 When the location counter (of the current subsection) is advanced, the
4989 intervening bytes are filled with @var{fill} which should be an
4990 absolute expression. If the comma and @var{fill} are omitted,
4991 @var{fill} defaults to zero.
4994 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4996 @cindex padding the location counter given a power of two
4997 @cindex @code{p2align} directive
4998 Pad the location counter (in the current subsection) to a particular
4999 storage boundary. The first expression (which must be absolute) is the
5000 number of low-order zero bits the location counter must have after
5001 advancement. For example @samp{.p2align 3} advances the location
5002 counter until it a multiple of 8. If the location counter is already a
5003 multiple of 8, no change is needed.
5005 The second expression (also absolute) gives the fill value to be stored in the
5006 padding bytes. It (and the comma) may be omitted. If it is omitted, the
5007 padding bytes are normally zero. However, on some systems, if the section is
5008 marked as containing code and the fill value is omitted, the space is filled
5009 with no-op instructions.
5011 The third expression is also absolute, and is also optional. If it is present,
5012 it is the maximum number of bytes that should be skipped by this alignment
5013 directive. If doing the alignment would require skipping more bytes than the
5014 specified maximum, then the alignment is not done at all. You can omit the
5015 fill value (the second argument) entirely by simply using two commas after the
5016 required alignment; this can be useful if you want the alignment to be filled
5017 with no-op instructions when appropriate.
5019 @cindex @code{p2alignw} directive
5020 @cindex @code{p2alignl} directive
5021 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5022 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5023 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5024 fill pattern as a four byte longword value. For example, @code{.p2alignw
5025 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5026 filled in with the value 0x368d (the exact placement of the bytes depends upon
5027 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5032 @section @code{.previous}
5034 @cindex @code{previous} directive
5035 @cindex Section Stack
5036 This is one of the ELF section stack manipulation directives. The others are
5037 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5038 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5039 (@pxref{PopSection}).
5041 This directive swaps the current section (and subsection) with most recently
5042 referenced section (and subsection) prior to this one. Multiple
5043 @code{.previous} directives in a row will flip between two sections (and their
5046 In terms of the section stack, this directive swaps the current section with
5047 the top section on the section stack.
5052 @section @code{.popsection}
5054 @cindex @code{popsection} directive
5055 @cindex Section Stack
5056 This is one of the ELF section stack manipulation directives. The others are
5057 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5058 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5061 This directive replaces the current section (and subsection) with the top
5062 section (and subsection) on the section stack. This section is popped off the
5067 @section @code{.print @var{string}}
5069 @cindex @code{print} directive
5070 @command{@value{AS}} will print @var{string} on the standard output during
5071 assembly. You must put @var{string} in double quotes.
5075 @section @code{.protected @var{names}}
5077 @cindex @code{protected} directive
5079 This is one of the ELF visibility directives. The other two are
5080 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
5082 This directive overrides the named symbols default visibility (which is set by
5083 their binding: local, global or weak). The directive sets the visibility to
5084 @code{protected} which means that any references to the symbols from within the
5085 components that defines them must be resolved to the definition in that
5086 component, even if a definition in another component would normally preempt
5091 @section @code{.psize @var{lines} , @var{columns}}
5093 @cindex @code{psize} directive
5094 @cindex listing control: paper size
5095 @cindex paper size, for listings
5096 Use this directive to declare the number of lines---and, optionally, the
5097 number of columns---to use for each page, when generating listings.
5099 If you do not use @code{.psize}, listings use a default line-count
5100 of 60. You may omit the comma and @var{columns} specification; the
5101 default width is 200 columns.
5103 @command{@value{AS}} generates formfeeds whenever the specified number of
5104 lines is exceeded (or whenever you explicitly request one, using
5107 If you specify @var{lines} as @code{0}, no formfeeds are generated save
5108 those explicitly specified with @code{.eject}.
5111 @section @code{.purgem @var{name}}
5113 @cindex @code{purgem} directive
5114 Undefine the macro @var{name}, so that later uses of the string will not be
5115 expanded. @xref{Macro}.
5119 @section @code{.pushsection @var{name} , @var{subsection}}
5121 @cindex @code{pushsection} directive
5122 @cindex Section Stack
5123 This is one of the ELF section stack manipulation directives. The others are
5124 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5125 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5128 This directive pushes the current section (and subsection) onto the
5129 top of the section stack, and then replaces the current section and
5130 subsection with @code{name} and @code{subsection}.
5134 @section @code{.quad @var{bignums}}
5136 @cindex @code{quad} directive
5137 @code{.quad} expects zero or more bignums, separated by commas. For
5138 each bignum, it emits
5140 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
5141 warning message; and just takes the lowest order 8 bytes of the bignum.
5142 @cindex eight-byte integer
5143 @cindex integer, 8-byte
5145 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
5146 hence @emph{quad}-word for 8 bytes.
5149 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
5150 warning message; and just takes the lowest order 16 bytes of the bignum.
5151 @cindex sixteen-byte integer
5152 @cindex integer, 16-byte
5156 @section @code{.rept @var{count}}
5158 @cindex @code{rept} directive
5159 Repeat the sequence of lines between the @code{.rept} directive and the next
5160 @code{.endr} directive @var{count} times.
5162 For example, assembling
5170 is equivalent to assembling
5179 @section @code{.sbttl "@var{subheading}"}
5181 @cindex @code{sbttl} directive
5182 @cindex subtitles for listings
5183 @cindex listing control: subtitle
5184 Use @var{subheading} as the title (third line, immediately after the
5185 title line) when generating assembly listings.
5187 This directive affects subsequent pages, as well as the current page if
5188 it appears within ten lines of the top of a page.
5192 @section @code{.scl @var{class}}
5194 @cindex @code{scl} directive
5195 @cindex symbol storage class (COFF)
5196 @cindex COFF symbol storage class
5197 Set the storage-class value for a symbol. This directive may only be
5198 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
5199 whether a symbol is static or external, or it may record further
5200 symbolic debugging information.
5203 The @samp{.scl} directive is primarily associated with COFF output; when
5204 configured to generate @code{b.out} output format, @command{@value{AS}}
5205 accepts this directive but ignores it.
5211 @section @code{.section @var{name}}
5213 @cindex named section
5214 Use the @code{.section} directive to assemble the following code into a section
5217 This directive is only supported for targets that actually support arbitrarily
5218 named sections; on @code{a.out} targets, for example, it is not accepted, even
5219 with a standard @code{a.out} section name.
5223 @c only print the extra heading if both COFF and ELF are set
5224 @subheading COFF Version
5227 @cindex @code{section} directive (COFF version)
5228 For COFF targets, the @code{.section} directive is used in one of the following
5232 .section @var{name}[, "@var{flags}"]
5233 .section @var{name}[, @var{subsegment}]
5236 If the optional argument is quoted, it is taken as flags to use for the
5237 section. Each flag is a single character. The following flags are recognized:
5240 bss section (uninitialized data)
5242 section is not loaded
5252 shared section (meaningful for PE targets)
5254 ignored. (For compatibility with the ELF version)
5257 If no flags are specified, the default flags depend upon the section name. If
5258 the section name is not recognized, the default will be for the section to be
5259 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
5260 from the section, rather than adding them, so if they are used on their own it
5261 will be as if no flags had been specified at all.
5263 If the optional argument to the @code{.section} directive is not quoted, it is
5264 taken as a subsegment number (@pxref{Sub-Sections}).
5269 @c only print the extra heading if both COFF and ELF are set
5270 @subheading ELF Version
5273 @cindex Section Stack
5274 This is one of the ELF section stack manipulation directives. The others are
5275 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5276 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5277 @code{.previous} (@pxref{Previous}).
5279 @cindex @code{section} directive (ELF version)
5280 For ELF targets, the @code{.section} directive is used like this:
5283 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]
5286 The optional @var{flags} argument is a quoted string which may contain any
5287 combination of the following characters:
5290 section is allocatable
5294 section is executable
5296 section is mergeable
5298 section contains zero terminated strings
5300 section is a member of a section group
5302 section is used for thread-local-storage
5305 The optional @var{type} argument may contain one of the following constants:
5308 section contains data
5310 section does not contain data (i.e., section only occupies space)
5312 section contains data which is used by things other than the program
5314 section contains an array of pointers to init functions
5316 section contains an array of pointers to finish functions
5317 @item @@preinit_array
5318 section contains an array of pointers to pre-init functions
5321 Many targets only support the first three section types.
5323 Note on targets where the @code{@@} character is the start of a comment (eg
5324 ARM) then another character is used instead. For example the ARM port uses the
5327 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
5328 be specified as well as an extra argument - @var{entsize} - like this:
5331 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
5334 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
5335 constants, each @var{entsize} octets long. Sections with both @code{M} and
5336 @code{S} must contain zero terminated strings where each character is
5337 @var{entsize} bytes long. The linker may remove duplicates within sections with
5338 the same name, same entity size and same flags. @var{entsize} must be an
5339 absolute expression.
5341 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
5342 be present along with an additional field like this:
5345 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
5348 The @var{GroupName} field specifies the name of the section group to which this
5349 particular section belongs. The optional linkage field can contain:
5352 indicates that only one copy of this section should be retained
5357 Note - if both the @var{M} and @var{G} flags are present then the fields for
5358 the Merge flag should come first, like this:
5361 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
5364 If no flags are specified, the default flags depend upon the section name. If
5365 the section name is not recognized, the default will be for the section to have
5366 none of the above flags: it will not be allocated in memory, nor writable, nor
5367 executable. The section will contain data.
5369 For ELF targets, the assembler supports another type of @code{.section}
5370 directive for compatibility with the Solaris assembler:
5373 .section "@var{name}"[, @var{flags}...]
5376 Note that the section name is quoted. There may be a sequence of comma
5380 section is allocatable
5384 section is executable
5386 section is used for thread local storage
5389 This directive replaces the current section and subsection. See the
5390 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
5391 some examples of how this directive and the other section stack directives
5397 @section @code{.set @var{symbol}, @var{expression}}
5399 @cindex @code{set} directive
5400 @cindex symbol value, setting
5401 Set the value of @var{symbol} to @var{expression}. This
5402 changes @var{symbol}'s value and type to conform to
5403 @var{expression}. If @var{symbol} was flagged as external, it remains
5404 flagged (@pxref{Symbol Attributes}).
5406 You may @code{.set} a symbol many times in the same assembly.
5408 If you @code{.set} a global symbol, the value stored in the object
5409 file is the last value stored into it.
5412 The syntax for @code{set} on the HPPA is
5413 @samp{@var{symbol} .set @var{expression}}.
5417 @section @code{.short @var{expressions}}
5419 @cindex @code{short} directive
5421 @code{.short} is normally the same as @samp{.word}.
5422 @xref{Word,,@code{.word}}.
5424 In some configurations, however, @code{.short} and @code{.word} generate
5425 numbers of different lengths; @pxref{Machine Dependencies}.
5429 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5432 This expects zero or more @var{expressions}, and emits
5433 a 16 bit number for each.
5438 @section @code{.single @var{flonums}}
5440 @cindex @code{single} directive
5441 @cindex floating point numbers (single)
5442 This directive assembles zero or more flonums, separated by commas. It
5443 has the same effect as @code{.float}.
5445 The exact kind of floating point numbers emitted depends on how
5446 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5450 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5451 numbers in @sc{ieee} format.
5457 @section @code{.size}
5459 This directive is used to set the size associated with a symbol.
5463 @c only print the extra heading if both COFF and ELF are set
5464 @subheading COFF Version
5467 @cindex @code{size} directive (COFF version)
5468 For COFF targets, the @code{.size} directive is only permitted inside
5469 @code{.def}/@code{.endef} pairs. It is used like this:
5472 .size @var{expression}
5476 @samp{.size} is only meaningful when generating COFF format output; when
5477 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5484 @c only print the extra heading if both COFF and ELF are set
5485 @subheading ELF Version
5488 @cindex @code{size} directive (ELF version)
5489 For ELF targets, the @code{.size} directive is used like this:
5492 .size @var{name} , @var{expression}
5495 This directive sets the size associated with a symbol @var{name}.
5496 The size in bytes is computed from @var{expression} which can make use of label
5497 arithmetic. This directive is typically used to set the size of function
5503 @section @code{.sleb128 @var{expressions}}
5505 @cindex @code{sleb128} directive
5506 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5507 compact, variable length representation of numbers used by the DWARF
5508 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5510 @ifclear no-space-dir
5512 @section @code{.skip @var{size} , @var{fill}}
5514 @cindex @code{skip} directive
5515 @cindex filling memory
5516 This directive emits @var{size} bytes, each of value @var{fill}. Both
5517 @var{size} and @var{fill} are absolute expressions. If the comma and
5518 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5522 @section @code{.space @var{size} , @var{fill}}
5524 @cindex @code{space} directive
5525 @cindex filling memory
5526 This directive emits @var{size} bytes, each of value @var{fill}. Both
5527 @var{size} and @var{fill} are absolute expressions. If the comma
5528 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5533 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5534 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5535 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5536 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5545 @section @code{.space}
5546 @cindex @code{space} directive
5548 On the AMD 29K, this directive is ignored; it is accepted for
5549 compatibility with other AMD 29K assemblers.
5552 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5553 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5559 @section @code{.stabd, .stabn, .stabs}
5561 @cindex symbolic debuggers, information for
5562 @cindex @code{stab@var{x}} directives
5563 There are three directives that begin @samp{.stab}.
5564 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5565 The symbols are not entered in the @command{@value{AS}} hash table: they
5566 cannot be referenced elsewhere in the source file.
5567 Up to five fields are required:
5571 This is the symbol's name. It may contain any character except
5572 @samp{\000}, so is more general than ordinary symbol names. Some
5573 debuggers used to code arbitrarily complex structures into symbol names
5577 An absolute expression. The symbol's type is set to the low 8 bits of
5578 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5579 and debuggers choke on silly bit patterns.
5582 An absolute expression. The symbol's ``other'' attribute is set to the
5583 low 8 bits of this expression.
5586 An absolute expression. The symbol's descriptor is set to the low 16
5587 bits of this expression.
5590 An absolute expression which becomes the symbol's value.
5593 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5594 or @code{.stabs} statement, the symbol has probably already been created;
5595 you get a half-formed symbol in your object file. This is
5596 compatible with earlier assemblers!
5599 @cindex @code{stabd} directive
5600 @item .stabd @var{type} , @var{other} , @var{desc}
5602 The ``name'' of the symbol generated is not even an empty string.
5603 It is a null pointer, for compatibility. Older assemblers used a
5604 null pointer so they didn't waste space in object files with empty
5607 The symbol's value is set to the location counter,
5608 relocatably. When your program is linked, the value of this symbol
5609 is the address of the location counter when the @code{.stabd} was
5612 @cindex @code{stabn} directive
5613 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5614 The name of the symbol is set to the empty string @code{""}.
5616 @cindex @code{stabs} directive
5617 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5618 All five fields are specified.
5624 @section @code{.string} "@var{str}"
5626 @cindex string, copying to object file
5627 @cindex @code{string} directive
5629 Copy the characters in @var{str} to the object file. You may specify more than
5630 one string to copy, separated by commas. Unless otherwise specified for a
5631 particular machine, the assembler marks the end of each string with a 0 byte.
5632 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5635 @section @code{.struct @var{expression}}
5637 @cindex @code{struct} directive
5638 Switch to the absolute section, and set the section offset to @var{expression},
5639 which must be an absolute expression. You might use this as follows:
5648 This would define the symbol @code{field1} to have the value 0, the symbol
5649 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5650 value 8. Assembly would be left in the absolute section, and you would need to
5651 use a @code{.section} directive of some sort to change to some other section
5652 before further assembly.
5656 @section @code{.subsection @var{name}}
5658 @cindex @code{subsection} directive
5659 @cindex Section Stack
5660 This is one of the ELF section stack manipulation directives. The others are
5661 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5662 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5665 This directive replaces the current subsection with @code{name}. The current
5666 section is not changed. The replaced subsection is put onto the section stack
5667 in place of the then current top of stack subsection.
5672 @section @code{.symver}
5673 @cindex @code{symver} directive
5674 @cindex symbol versioning
5675 @cindex versions of symbols
5676 Use the @code{.symver} directive to bind symbols to specific version nodes
5677 within a source file. This is only supported on ELF platforms, and is
5678 typically used when assembling files to be linked into a shared library.
5679 There are cases where it may make sense to use this in objects to be bound
5680 into an application itself so as to override a versioned symbol from a
5683 For ELF targets, the @code{.symver} directive can be used like this:
5685 .symver @var{name}, @var{name2@@nodename}
5687 If the symbol @var{name} is defined within the file
5688 being assembled, the @code{.symver} directive effectively creates a symbol
5689 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5690 just don't try and create a regular alias is that the @var{@@} character isn't
5691 permitted in symbol names. The @var{name2} part of the name is the actual name
5692 of the symbol by which it will be externally referenced. The name @var{name}
5693 itself is merely a name of convenience that is used so that it is possible to
5694 have definitions for multiple versions of a function within a single source
5695 file, and so that the compiler can unambiguously know which version of a
5696 function is being mentioned. The @var{nodename} portion of the alias should be
5697 the name of a node specified in the version script supplied to the linker when
5698 building a shared library. If you are attempting to override a versioned
5699 symbol from a shared library, then @var{nodename} should correspond to the
5700 nodename of the symbol you are trying to override.
5702 If the symbol @var{name} is not defined within the file being assembled, all
5703 references to @var{name} will be changed to @var{name2@@nodename}. If no
5704 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5707 Another usage of the @code{.symver} directive is:
5709 .symver @var{name}, @var{name2@@@@nodename}
5711 In this case, the symbol @var{name} must exist and be defined within
5712 the file being assembled. It is similar to @var{name2@@nodename}. The
5713 difference is @var{name2@@@@nodename} will also be used to resolve
5714 references to @var{name2} by the linker.
5716 The third usage of the @code{.symver} directive is:
5718 .symver @var{name}, @var{name2@@@@@@nodename}
5720 When @var{name} is not defined within the
5721 file being assembled, it is treated as @var{name2@@nodename}. When
5722 @var{name} is defined within the file being assembled, the symbol
5723 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5728 @section @code{.tag @var{structname}}
5730 @cindex COFF structure debugging
5731 @cindex structure debugging, COFF
5732 @cindex @code{tag} directive
5733 This directive is generated by compilers to include auxiliary debugging
5734 information in the symbol table. It is only permitted inside
5735 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5736 definitions in the symbol table with instances of those structures.
5739 @samp{.tag} is only used when generating COFF format output; when
5740 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5746 @section @code{.text @var{subsection}}
5748 @cindex @code{text} directive
5749 Tells @command{@value{AS}} to assemble the following statements onto the end of
5750 the text subsection numbered @var{subsection}, which is an absolute
5751 expression. If @var{subsection} is omitted, subsection number zero
5755 @section @code{.title "@var{heading}"}
5757 @cindex @code{title} directive
5758 @cindex listing control: title line
5759 Use @var{heading} as the title (second line, immediately after the
5760 source file name and pagenumber) when generating assembly listings.
5762 This directive affects subsequent pages, as well as the current page if
5763 it appears within ten lines of the top of a page.
5767 @section @code{.type}
5769 This directive is used to set the type of a symbol.
5773 @c only print the extra heading if both COFF and ELF are set
5774 @subheading COFF Version
5777 @cindex COFF symbol type
5778 @cindex symbol type, COFF
5779 @cindex @code{type} directive (COFF version)
5780 For COFF targets, this directive is permitted only within
5781 @code{.def}/@code{.endef} pairs. It is used like this:
5787 This records the integer @var{int} as the type attribute of a symbol table
5791 @samp{.type} is associated only with COFF format output; when
5792 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5793 directive but ignores it.
5799 @c only print the extra heading if both COFF and ELF are set
5800 @subheading ELF Version
5803 @cindex ELF symbol type
5804 @cindex symbol type, ELF
5805 @cindex @code{type} directive (ELF version)
5806 For ELF targets, the @code{.type} directive is used like this:
5809 .type @var{name} , @var{type description}
5812 This sets the type of symbol @var{name} to be either a
5813 function symbol or an object symbol. There are five different syntaxes
5814 supported for the @var{type description} field, in order to provide
5815 compatibility with various other assemblers. The syntaxes supported are:
5818 .type <name>,#function
5819 .type <name>,#object
5821 .type <name>,@@function
5822 .type <name>,@@object
5824 .type <name>,%function
5825 .type <name>,%object
5827 .type <name>,"function"
5828 .type <name>,"object"
5830 .type <name> STT_FUNCTION
5831 .type <name> STT_OBJECT
5837 @section @code{.uleb128 @var{expressions}}
5839 @cindex @code{uleb128} directive
5840 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5841 compact, variable length representation of numbers used by the DWARF
5842 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5846 @section @code{.val @var{addr}}
5848 @cindex @code{val} directive
5849 @cindex COFF value attribute
5850 @cindex value attribute, COFF
5851 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5852 records the address @var{addr} as the value attribute of a symbol table
5856 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5857 configured for @code{b.out}, it accepts this directive but ignores it.
5863 @section @code{.version "@var{string}"}
5865 @cindex @code{version} directive
5866 This directive creates a @code{.note} section and places into it an ELF
5867 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5872 @section @code{.vtable_entry @var{table}, @var{offset}}
5874 @cindex @code{vtable_entry} directive
5875 This directive finds or creates a symbol @code{table} and creates a
5876 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5879 @section @code{.vtable_inherit @var{child}, @var{parent}}
5881 @cindex @code{vtable_inherit} directive
5882 This directive finds the symbol @code{child} and finds or creates the symbol
5883 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5884 parent whose addend is the value of the child symbol. As a special case the
5885 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5889 @section @code{.warning "@var{string}"}
5890 @cindex warning directive
5891 Similar to the directive @code{.error}
5892 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
5895 @section @code{.weak @var{names}}
5897 @cindex @code{weak} directive
5898 This directive sets the weak attribute on the comma separated list of symbol
5899 @code{names}. If the symbols do not already exist, they will be created.
5901 On COFF targets other than PE, weak symbols are a GNU extension. This
5902 directive sets the weak attribute on the comma separated list of symbol
5903 @code{names}. If the symbols do not already exist, they will be created.
5905 On the PE target, weak symbols are supported natively as weak aliases.
5906 When a weak symbol is created that is not an alias, GAS creates an
5907 alternate symbol to hold the default value.
5910 @section @code{.word @var{expressions}}
5912 @cindex @code{word} directive
5913 This directive expects zero or more @var{expressions}, of any section,
5914 separated by commas.
5917 For each expression, @command{@value{AS}} emits a 32-bit number.
5920 For each expression, @command{@value{AS}} emits a 16-bit number.
5925 The size of the number emitted, and its byte order,
5926 depend on what target computer the assembly is for.
5929 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5930 @c happen---32-bit addressability, period; no long/short jumps.
5931 @ifset DIFF-TBL-KLUGE
5932 @cindex difference tables altered
5933 @cindex altered difference tables
5935 @emph{Warning: Special Treatment to support Compilers}
5939 Machines with a 32-bit address space, but that do less than 32-bit
5940 addressing, require the following special treatment. If the machine of
5941 interest to you does 32-bit addressing (or doesn't require it;
5942 @pxref{Machine Dependencies}), you can ignore this issue.
5945 In order to assemble compiler output into something that works,
5946 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5947 Directives of the form @samp{.word sym1-sym2} are often emitted by
5948 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5949 directive of the form @samp{.word sym1-sym2}, and the difference between
5950 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5951 creates a @dfn{secondary jump table}, immediately before the next label.
5952 This secondary jump table is preceded by a short-jump to the
5953 first byte after the secondary table. This short-jump prevents the flow
5954 of control from accidentally falling into the new table. Inside the
5955 table is a long-jump to @code{sym2}. The original @samp{.word}
5956 contains @code{sym1} minus the address of the long-jump to
5959 If there were several occurrences of @samp{.word sym1-sym2} before the
5960 secondary jump table, all of them are adjusted. If there was a
5961 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5962 long-jump to @code{sym4} is included in the secondary jump table,
5963 and the @code{.word} directives are adjusted to contain @code{sym3}
5964 minus the address of the long-jump to @code{sym4}; and so on, for as many
5965 entries in the original jump table as necessary.
5968 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5969 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5970 assembly language programmers.
5973 @c end DIFF-TBL-KLUGE
5976 @section Deprecated Directives
5978 @cindex deprecated directives
5979 @cindex obsolescent directives
5980 One day these directives won't work.
5981 They are included for compatibility with older assemblers.
5988 @node Machine Dependencies
5989 @chapter Machine Dependent Features
5991 @cindex machine dependencies
5992 The machine instruction sets are (almost by definition) different on
5993 each machine where @command{@value{AS}} runs. Floating point representations
5994 vary as well, and @command{@value{AS}} often supports a few additional
5995 directives or command-line options for compatibility with other
5996 assemblers on a particular platform. Finally, some versions of
5997 @command{@value{AS}} support special pseudo-instructions for branch
6000 This chapter discusses most of these differences, though it does not
6001 include details on any machine's instruction set. For details on that
6002 subject, see the hardware manufacturer's manual.
6006 * AMD29K-Dependent:: AMD 29K Dependent Features
6009 * Alpha-Dependent:: Alpha Dependent Features
6012 * ARC-Dependent:: ARC Dependent Features
6015 * ARM-Dependent:: ARM Dependent Features
6018 * CRIS-Dependent:: CRIS Dependent Features
6021 * D10V-Dependent:: D10V Dependent Features
6024 * D30V-Dependent:: D30V Dependent Features
6027 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6030 * H8/500-Dependent:: Renesas H8/500 Dependent Features
6033 * HPPA-Dependent:: HPPA Dependent Features
6036 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
6039 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
6042 * i860-Dependent:: Intel 80860 Dependent Features
6045 * i960-Dependent:: Intel 80960 Dependent Features
6048 * IA-64-Dependent:: Intel IA-64 Dependent Features
6051 * IP2K-Dependent:: IP2K Dependent Features
6054 * M32R-Dependent:: M32R Dependent Features
6057 * M68K-Dependent:: M680x0 Dependent Features
6060 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
6063 * M88K-Dependent:: M880x0 Dependent Features
6066 * MIPS-Dependent:: MIPS Dependent Features
6069 * MMIX-Dependent:: MMIX Dependent Features
6072 * MSP430-Dependent:: MSP430 Dependent Features
6075 * SH-Dependent:: Renesas / SuperH SH Dependent Features
6076 * SH64-Dependent:: SuperH SH64 Dependent Features
6079 * PDP-11-Dependent:: PDP-11 Dependent Features
6082 * PJ-Dependent:: picoJava Dependent Features
6085 * PPC-Dependent:: PowerPC Dependent Features
6088 * Sparc-Dependent:: SPARC Dependent Features
6091 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
6094 * V850-Dependent:: V850 Dependent Features
6097 * Xtensa-Dependent:: Xtensa Dependent Features
6100 * Z8000-Dependent:: Z8000 Dependent Features
6103 * Vax-Dependent:: VAX Dependent Features
6110 @c The following major nodes are *sections* in the GENERIC version, *chapters*
6111 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
6112 @c peculiarity: to preserve cross-references, there must be a node called
6113 @c "Machine Dependencies". Hence the conditional nodenames in each
6114 @c major node below. Node defaulting in makeinfo requires adjacency of
6115 @c node and sectioning commands; hence the repetition of @chapter BLAH
6116 @c in both conditional blocks.
6119 @include c-a29k.texi
6123 @include c-alpha.texi
6135 @include c-cris.texi
6140 @node Machine Dependencies
6141 @chapter Machine Dependent Features
6143 The machine instruction sets are different on each Renesas chip family,
6144 and there are also some syntax differences among the families. This
6145 chapter describes the specific @command{@value{AS}} features for each
6149 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6150 * H8/500-Dependent:: Renesas H8/500 Dependent Features
6151 * SH-Dependent:: Renesas SH Dependent Features
6158 @include c-d10v.texi
6162 @include c-d30v.texi
6166 @include c-h8300.texi
6170 @include c-h8500.texi
6174 @include c-hppa.texi
6178 @include c-i370.texi
6182 @include c-i386.texi
6186 @include c-i860.texi
6190 @include c-i960.texi
6194 @include c-ia64.texi
6198 @include c-ip2k.texi
6202 @include c-m32r.texi
6206 @include c-m68k.texi
6210 @include c-m68hc11.texi
6214 @include c-m88k.texi
6218 @include c-mips.texi
6222 @include c-mmix.texi
6226 @include c-msp430.texi
6230 @include c-ns32k.texi
6234 @include c-pdp11.texi
6247 @include c-sh64.texi
6251 @include c-sparc.texi
6255 @include c-tic54x.texi
6267 @include c-v850.texi
6271 @include c-xtensa.texi
6275 @c reverse effect of @down at top of generic Machine-Dep chapter
6279 @node Reporting Bugs
6280 @chapter Reporting Bugs
6281 @cindex bugs in assembler
6282 @cindex reporting bugs in assembler
6284 Your bug reports play an essential role in making @command{@value{AS}} reliable.
6286 Reporting a bug may help you by bringing a solution to your problem, or it may
6287 not. But in any case the principal function of a bug report is to help the
6288 entire community by making the next version of @command{@value{AS}} work better.
6289 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
6291 In order for a bug report to serve its purpose, you must include the
6292 information that enables us to fix the bug.
6295 * Bug Criteria:: Have you found a bug?
6296 * Bug Reporting:: How to report bugs
6300 @section Have You Found a Bug?
6301 @cindex bug criteria
6303 If you are not sure whether you have found a bug, here are some guidelines:
6306 @cindex fatal signal
6307 @cindex assembler crash
6308 @cindex crash of assembler
6310 If the assembler gets a fatal signal, for any input whatever, that is a
6311 @command{@value{AS}} bug. Reliable assemblers never crash.
6313 @cindex error on valid input
6315 If @command{@value{AS}} produces an error message for valid input, that is a bug.
6317 @cindex invalid input
6319 If @command{@value{AS}} does not produce an error message for invalid input, that
6320 is a bug. However, you should note that your idea of ``invalid input'' might
6321 be our idea of ``an extension'' or ``support for traditional practice''.
6324 If you are an experienced user of assemblers, your suggestions for improvement
6325 of @command{@value{AS}} are welcome in any case.
6329 @section How to Report Bugs
6331 @cindex assembler bugs, reporting
6333 A number of companies and individuals offer support for @sc{gnu} products. If
6334 you obtained @command{@value{AS}} from a support organization, we recommend you
6335 contact that organization first.
6337 You can find contact information for many support companies and
6338 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
6341 In any event, we also recommend that you send bug reports for @command{@value{AS}}
6342 to @samp{bug-binutils@@gnu.org}.
6344 The fundamental principle of reporting bugs usefully is this:
6345 @strong{report all the facts}. If you are not sure whether to state a
6346 fact or leave it out, state it!
6348 Often people omit facts because they think they know what causes the problem
6349 and assume that some details do not matter. Thus, you might assume that the
6350 name of a symbol you use in an example does not matter. Well, probably it does
6351 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
6352 happens to fetch from the location where that name is stored in memory;
6353 perhaps, if the name were different, the contents of that location would fool
6354 the assembler into doing the right thing despite the bug. Play it safe and
6355 give a specific, complete example. That is the easiest thing for you to do,
6356 and the most helpful.
6358 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
6359 it is new to us. Therefore, always write your bug reports on the assumption
6360 that the bug has not been reported previously.
6362 Sometimes people give a few sketchy facts and ask, ``Does this ring a
6363 bell?'' This cannot help us fix a bug, so it is basically useless. We
6364 respond by asking for enough details to enable us to investigate.
6365 You might as well expedite matters by sending them to begin with.
6367 To enable us to fix the bug, you should include all these things:
6371 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
6372 it with the @samp{--version} argument.
6374 Without this, we will not know whether there is any point in looking for
6375 the bug in the current version of @command{@value{AS}}.
6378 Any patches you may have applied to the @command{@value{AS}} source.
6381 The type of machine you are using, and the operating system name and
6385 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
6389 The command arguments you gave the assembler to assemble your example and
6390 observe the bug. To guarantee you will not omit something important, list them
6391 all. A copy of the Makefile (or the output from make) is sufficient.
6393 If we were to try to guess the arguments, we would probably guess wrong
6394 and then we might not encounter the bug.
6397 A complete input file that will reproduce the bug. If the bug is observed when
6398 the assembler is invoked via a compiler, send the assembler source, not the
6399 high level language source. Most compilers will produce the assembler source
6400 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
6401 the options @samp{-v --save-temps}; this will save the assembler source in a
6402 file with an extension of @file{.s}, and also show you exactly how
6403 @command{@value{AS}} is being run.
6406 A description of what behavior you observe that you believe is
6407 incorrect. For example, ``It gets a fatal signal.''
6409 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
6410 will certainly notice it. But if the bug is incorrect output, we might not
6411 notice unless it is glaringly wrong. You might as well not give us a chance to
6414 Even if the problem you experience is a fatal signal, you should still say so
6415 explicitly. Suppose something strange is going on, such as, your copy of
6416 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
6417 library on your system. (This has happened!) Your copy might crash and ours
6418 would not. If you told us to expect a crash, then when ours fails to crash, we
6419 would know that the bug was not happening for us. If you had not told us to
6420 expect a crash, then we would not be able to draw any conclusion from our
6424 If you wish to suggest changes to the @command{@value{AS}} source, send us context
6425 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
6426 option. Always send diffs from the old file to the new file. If you even
6427 discuss something in the @command{@value{AS}} source, refer to it by context, not
6430 The line numbers in our development sources will not match those in your
6431 sources. Your line numbers would convey no useful information to us.
6434 Here are some things that are not necessary:
6438 A description of the envelope of the bug.
6440 Often people who encounter a bug spend a lot of time investigating
6441 which changes to the input file will make the bug go away and which
6442 changes will not affect it.
6444 This is often time consuming and not very useful, because the way we
6445 will find the bug is by running a single example under the debugger
6446 with breakpoints, not by pure deduction from a series of examples.
6447 We recommend that you save your time for something else.
6449 Of course, if you can find a simpler example to report @emph{instead}
6450 of the original one, that is a convenience for us. Errors in the
6451 output will be easier to spot, running under the debugger will take
6452 less time, and so on.
6454 However, simplification is not vital; if you do not want to do this,
6455 report the bug anyway and send us the entire test case you used.
6458 A patch for the bug.
6460 A patch for the bug does help us if it is a good one. But do not omit
6461 the necessary information, such as the test case, on the assumption that
6462 a patch is all we need. We might see problems with your patch and decide
6463 to fix the problem another way, or we might not understand it at all.
6465 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6466 construct an example that will make the program follow a certain path through
6467 the code. If you do not send us the example, we will not be able to construct
6468 one, so we will not be able to verify that the bug is fixed.
6470 And if we cannot understand what bug you are trying to fix, or why your
6471 patch should be an improvement, we will not install it. A test case will
6472 help us to understand.
6475 A guess about what the bug is or what it depends on.
6477 Such guesses are usually wrong. Even we cannot guess right about such
6478 things without first using the debugger to find the facts.
6481 @node Acknowledgements
6482 @chapter Acknowledgements
6484 If you have contributed to GAS and your name isn't listed here,
6485 it is not meant as a slight. We just don't know about it. Send mail to the
6486 maintainer, and we'll correct the situation. Currently
6488 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6490 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6493 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6494 information and the 68k series machines, most of the preprocessing pass, and
6495 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6497 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6498 many bug fixes, including merging support for several processors, breaking GAS
6499 up to handle multiple object file format back ends (including heavy rewrite,
6500 testing, an integration of the coff and b.out back ends), adding configuration
6501 including heavy testing and verification of cross assemblers and file splits
6502 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6503 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6504 port (including considerable amounts of reverse engineering), a SPARC opcode
6505 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6506 assertions and made them work, much other reorganization, cleanup, and lint.
6508 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6509 in format-specific I/O modules.
6511 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6512 has done much work with it since.
6514 The Intel 80386 machine description was written by Eliot Dresselhaus.
6516 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6518 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6519 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6521 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6522 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6523 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6524 support a.out format.
6526 Support for the Zilog Z8k and Renesas H8/300 and H8/500 processors (tc-z8k,
6527 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6528 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6529 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6532 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6533 simplified the configuration of which versions accept which directives. He
6534 updated the 68k machine description so that Motorola's opcodes always produced
6535 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
6536 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6537 cross-compilation support, and one bug in relaxation that took a week and
6538 required the proverbial one-bit fix.
6540 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6541 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6542 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6543 PowerPC assembler, and made a few other minor patches.
6545 Steve Chamberlain made GAS able to generate listings.
6547 Hewlett-Packard contributed support for the HP9000/300.
6549 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6550 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6551 formats). This work was supported by both the Center for Software Science at
6552 the University of Utah and Cygnus Support.
6554 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6555 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6556 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6557 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6558 and some initial 64-bit support).
6560 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
6562 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6563 support for openVMS/Alpha.
6565 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6568 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
6569 Inc. added support for Xtensa processors.
6571 Several engineers at Cygnus Support have also provided many small bug fixes and
6572 configuration enhancements.
6574 Many others have contributed large or small bugfixes and enhancements. If
6575 you have contributed significant work and are not mentioned on this list, and
6576 want to be, let us know. Some of the history has been lost; we are not
6577 intentionally leaving anyone out.
projects / binutils-gdb.git / blob