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, 2006, 2007, 2008, 2009
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 @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
107 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
109 Permission is granted to copy, distribute and/or modify this document
110 under the terms of the GNU Free Documentation License, Version 1.3
111 or any later version published by the Free Software Foundation;
112 with no Invariant Sections, with no Front-Cover Texts, and with no
113 Back-Cover Texts. A copy of the license is included in the
114 section entitled ``GNU Free Documentation License''.
120 @title Using @value{AS}
121 @subtitle The @sc{gnu} Assembler
123 @subtitle for the @value{TARGET} family
125 @ifset VERSION_PACKAGE
127 @subtitle @value{VERSION_PACKAGE}
130 @subtitle Version @value{VERSION}
133 The Free Software Foundation Inc.@: thanks The Nice Computer
134 Company of Australia for loaning Dean Elsner to write the
135 first (Vax) version of @command{as} for Project @sc{gnu}.
136 The proprietors, management and staff of TNCCA thank FSF for
137 distracting the boss while they got some work
140 @author Dean Elsner, Jay Fenlason & friends
144 \hfill {\it Using {\tt @value{AS}}}\par
145 \hfill Edited by Cygnus Support\par
147 %"boxit" macro for figures:
148 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
149 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
150 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
151 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
152 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
155 @vskip 0pt plus 1filll
156 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
157 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
159 Permission is granted to copy, distribute and/or modify this document
160 under the terms of the GNU Free Documentation License, Version 1.3
161 or any later version published by the Free Software Foundation;
162 with no Invariant Sections, with no Front-Cover Texts, and with no
163 Back-Cover Texts. A copy of the license is included in the
164 section entitled ``GNU Free Documentation License''.
171 @top Using @value{AS}
173 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}}
174 @ifset VERSION_PACKAGE
175 @value{VERSION_PACKAGE}
177 version @value{VERSION}.
179 This version of the file describes @command{@value{AS}} configured to generate
180 code for @value{TARGET} architectures.
183 This document is distributed under the terms of the GNU Free
184 Documentation License. A copy of the license is included in the
185 section entitled ``GNU Free Documentation License''.
188 * Overview:: Overview
189 * Invoking:: Command-Line Options
191 * Sections:: Sections and Relocation
193 * Expressions:: Expressions
194 * Pseudo Ops:: Assembler Directives
196 * Object Attributes:: Object Attributes
198 * Machine Dependencies:: Machine Dependent Features
199 * Reporting Bugs:: Reporting Bugs
200 * Acknowledgements:: Who Did What
201 * GNU Free Documentation License:: GNU Free Documentation License
202 * AS Index:: AS Index
209 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
211 This version of the manual describes @command{@value{AS}} configured to generate
212 code for @value{TARGET} architectures.
216 @cindex invocation summary
217 @cindex option summary
218 @cindex summary of options
219 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
220 see @ref{Invoking,,Command-Line Options}.
222 @c man title AS the portable GNU assembler.
226 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
230 @c We don't use deffn and friends for the following because they seem
231 @c to be limited to one line for the header.
233 @c man begin SYNOPSIS
234 @value{AS} [@b{-a}[@b{cdghlns}][=@var{file}]] [@b{--alternate}] [@b{-D}]
235 [@b{--debug-prefix-map} @var{old}=@var{new}]
236 [@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}]
237 [@b{--gstabs+}] [@b{--gdwarf-2}] [@b{--help}] [@b{-I} @var{dir}] [@b{-J}]
238 [@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}]
239 [@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}]
240 [@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}] [@b{-o}
241 @var{objfile}] [@b{-R}] [@b{--reduce-memory-overheads}] [@b{--statistics}]
242 [@b{-v}] [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}]
243 [@b{--fatal-warnings}] [@b{-w}] [@b{-x}] [@b{-Z}] [@b{@@@var{FILE}}]
244 [@b{--target-help}] [@var{target-options}]
245 [@b{--}|@var{files} @dots{}]
247 @c Target dependent options are listed below. Keep the list sorted.
248 @c Add an empty line for separation.
251 @emph{Target Alpha options:}
253 [@b{-mdebug} | @b{-no-mdebug}]
254 [@b{-replace} | @b{-noreplace}]
255 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
256 [@b{-F}] [@b{-32addr}]
260 @emph{Target ARC options:}
266 @emph{Target ARM options:}
267 @c Don't document the deprecated options
268 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
269 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
270 [@b{-mfpu}=@var{floating-point-format}]
271 [@b{-mfloat-abi}=@var{abi}]
272 [@b{-meabi}=@var{ver}]
275 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
276 @b{-mapcs-reentrant}]
277 [@b{-mthumb-interwork}] [@b{-k}]
281 @emph{Target Blackfin options:}
282 [@b{-mcpu}=@var{processor}[-@var{sirevision}]]
289 @emph{Target CRIS options:}
290 [@b{--underscore} | @b{--no-underscore}]
292 [@b{--emulation=criself} | @b{--emulation=crisaout}]
293 [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}]
294 @c Deprecated -- deliberately not documented.
299 @emph{Target D10V options:}
304 @emph{Target D30V options:}
305 [@b{-O}|@b{-n}|@b{-N}]
309 @emph{Target H8/300 options:}
313 @c HPPA has no machine-dependent assembler options (yet).
317 @emph{Target i386 options:}
318 [@b{--32}|@b{--64}] [@b{-n}]
319 [@b{-march}=@var{CPU}[+@var{EXTENSION}@dots{}]] [@b{-mtune}=@var{CPU}]
323 @emph{Target i960 options:}
324 @c see md_parse_option in tc-i960.c
325 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
327 [@b{-b}] [@b{-no-relax}]
331 @emph{Target IA-64 options:}
332 [@b{-mconstant-gp}|@b{-mauto-pic}]
333 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
335 [@b{-mtune=itanium1}|@b{-mtune=itanium2}]
336 [@b{-munwind-check=warning}|@b{-munwind-check=error}]
337 [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}]
338 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
342 @emph{Target IP2K options:}
343 [@b{-mip2022}|@b{-mip2022ext}]
347 @emph{Target M32C options:}
348 [@b{-m32c}|@b{-m16c}] [-relax] [-h-tick-hex]
352 @emph{Target M32R options:}
353 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
358 @emph{Target M680X0 options:}
359 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
363 @emph{Target M68HC11 options:}
364 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}]
365 [@b{-mshort}|@b{-mlong}]
366 [@b{-mshort-double}|@b{-mlong-double}]
367 [@b{--force-long-branches}] [@b{--short-branches}]
368 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
369 [@b{--print-opcodes}] [@b{--generate-example}]
373 @emph{Target MCORE options:}
374 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
375 [@b{-mcpu=[210|340]}]
378 @emph{Target MICROBLAZE options:}
379 @c MicroBlaze has no machine-dependent assembler options.
383 @emph{Target MIPS options:}
384 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
385 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
386 [@b{-non_shared}] [@b{-xgot} [@b{-mvxworks-pic}]
387 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
388 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
389 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
390 [@b{-mips64}] [@b{-mips64r2}]
391 [@b{-construct-floats}] [@b{-no-construct-floats}]
392 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
393 [@b{-mips16}] [@b{-no-mips16}]
394 [@b{-msmartmips}] [@b{-mno-smartmips}]
395 [@b{-mips3d}] [@b{-no-mips3d}]
396 [@b{-mdmx}] [@b{-no-mdmx}]
397 [@b{-mdsp}] [@b{-mno-dsp}]
398 [@b{-mdspr2}] [@b{-mno-dspr2}]
399 [@b{-mmt}] [@b{-mno-mt}]
400 [@b{-mfix7000}] [@b{-mno-fix7000}]
401 [@b{-mfix-vr4120}] [@b{-mno-fix-vr4120}]
402 [@b{-mfix-vr4130}] [@b{-mno-fix-vr4130}]
403 [@b{-mdebug}] [@b{-no-mdebug}]
404 [@b{-mpdr}] [@b{-mno-pdr}]
408 @emph{Target MMIX options:}
409 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
410 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
411 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
412 [@b{--linker-allocated-gregs}]
416 @emph{Target PDP11 options:}
417 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
418 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
419 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
423 @emph{Target picoJava options:}
428 @emph{Target PowerPC options:}
429 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
430 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}]
431 [@b{-mcom}|@b{-many}|@b{-maltivec}|@b{-mvsx}] [@b{-memb}]
432 [@b{-mregnames}|@b{-mno-regnames}]
433 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
434 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
435 [@b{-msolaris}|@b{-mno-solaris}]
439 @emph{Target RX options:}
440 [@b{-mlittle-endian}|@b{-mbig-endian}]
441 [@b{-m32bit-ints}|@b{-m16bit-ints}]
442 [@b{-m32bit-doubles}|@b{-m64bit-doubles}]
446 @emph{Target s390 options:}
447 [@b{-m31}|@b{-m64}] [@b{-mesa}|@b{-mzarch}] [@b{-march}=@var{CPU}]
448 [@b{-mregnames}|@b{-mno-regnames}]
449 [@b{-mwarn-areg-zero}]
453 @emph{Target SCORE options:}
454 [@b{-EB}][@b{-EL}][@b{-FIXDD}][@b{-NWARN}]
455 [@b{-SCORE5}][@b{-SCORE5U}][@b{-SCORE7}][@b{-SCORE3}]
456 [@b{-march=score7}][@b{-march=score3}]
457 [@b{-USE_R1}][@b{-KPIC}][@b{-O0}][@b{-G} @var{num}][@b{-V}]
461 @emph{Target SPARC options:}
462 @c The order here is important. See c-sparc.texi.
463 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
464 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
465 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
470 @emph{Target TIC54X options:}
471 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
472 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
477 @emph{Target Z80 options:}
478 [@b{-z80}] [@b{-r800}]
479 [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}]
480 [@b{ -ignore-unportable-instructions}] [@b{-Wnup}]
481 [@b{ -warn-undocumented-instructions}] [@b{-Wud}]
482 [@b{ -warn-unportable-instructions}] [@b{-Wup}]
483 [@b{ -forbid-undocumented-instructions}] [@b{-Fud}]
484 [@b{ -forbid-unportable-instructions}] [@b{-Fup}]
488 @c Z8000 has no machine-dependent assembler options
492 @emph{Target Xtensa options:}
493 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
494 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
495 [@b{--[no-]transform}]
496 [@b{--rename-section} @var{oldname}=@var{newname}]
504 @include at-file.texi
507 Turn on listings, in any of a variety of ways:
511 omit false conditionals
514 omit debugging directives
517 include general information, like @value{AS} version and options passed
520 include high-level source
526 include macro expansions
529 omit forms processing
535 set the name of the listing file
538 You may combine these options; for example, use @samp{-aln} for assembly
539 listing without forms processing. The @samp{=file} option, if used, must be
540 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
543 Begin in alternate macro mode.
545 @xref{Altmacro,,@code{.altmacro}}.
549 Ignored. This option is accepted for script compatibility with calls to
552 @item --debug-prefix-map @var{old}=@var{new}
553 When assembling files in directory @file{@var{old}}, record debugging
554 information describing them as in @file{@var{new}} instead.
556 @item --defsym @var{sym}=@var{value}
557 Define the symbol @var{sym} to be @var{value} before assembling the input file.
558 @var{value} must be an integer constant. As in C, a leading @samp{0x}
559 indicates a hexadecimal value, and a leading @samp{0} indicates an octal
560 value. The value of the symbol can be overridden inside a source file via the
561 use of a @code{.set} pseudo-op.
564 ``fast''---skip whitespace and comment preprocessing (assume source is
569 Generate debugging information for each assembler source line using whichever
570 debug format is preferred by the target. This currently means either STABS,
574 Generate stabs debugging information for each assembler line. This
575 may help debugging assembler code, if the debugger can handle it.
578 Generate stabs debugging information for each assembler line, with GNU
579 extensions that probably only gdb can handle, and that could make other
580 debuggers crash or refuse to read your program. This
581 may help debugging assembler code. Currently the only GNU extension is
582 the location of the current working directory at assembling time.
585 Generate DWARF2 debugging information for each assembler line. This
586 may help debugging assembler code, if the debugger can handle it. Note---this
587 option is only supported by some targets, not all of them.
590 Print a summary of the command line options and exit.
593 Print a summary of all target specific options and exit.
596 Add directory @var{dir} to the search list for @code{.include} directives.
599 Don't warn about signed overflow.
602 @ifclear DIFF-TBL-KLUGE
603 This option is accepted but has no effect on the @value{TARGET} family.
605 @ifset DIFF-TBL-KLUGE
606 Issue warnings when difference tables altered for long displacements.
611 Keep (in the symbol table) local symbols. These symbols start with
612 system-specific local label prefixes, typically @samp{.L} for ELF systems
613 or @samp{L} for traditional a.out systems.
618 @item --listing-lhs-width=@var{number}
619 Set the maximum width, in words, of the output data column for an assembler
620 listing to @var{number}.
622 @item --listing-lhs-width2=@var{number}
623 Set the maximum width, in words, of the output data column for continuation
624 lines in an assembler listing to @var{number}.
626 @item --listing-rhs-width=@var{number}
627 Set the maximum width of an input source line, as displayed in a listing, to
630 @item --listing-cont-lines=@var{number}
631 Set the maximum number of lines printed in a listing for a single line of input
634 @item -o @var{objfile}
635 Name the object-file output from @command{@value{AS}} @var{objfile}.
638 Fold the data section into the text section.
640 @kindex --hash-size=@var{number}
641 Set the default size of GAS's hash tables to a prime number close to
642 @var{number}. Increasing this value can reduce the length of time it takes the
643 assembler to perform its tasks, at the expense of increasing the assembler's
644 memory requirements. Similarly reducing this value can reduce the memory
645 requirements at the expense of speed.
647 @item --reduce-memory-overheads
648 This option reduces GAS's memory requirements, at the expense of making the
649 assembly processes slower. Currently this switch is a synonym for
650 @samp{--hash-size=4051}, but in the future it may have other effects as well.
653 Print the maximum space (in bytes) and total time (in seconds) used by
656 @item --strip-local-absolute
657 Remove local absolute symbols from the outgoing symbol table.
661 Print the @command{as} version.
664 Print the @command{as} version and exit.
668 Suppress warning messages.
670 @item --fatal-warnings
671 Treat warnings as errors.
674 Don't suppress warning messages or treat them as errors.
683 Generate an object file even after errors.
685 @item -- | @var{files} @dots{}
686 Standard input, or source files to assemble.
691 The following options are available when @value{AS} is configured for
696 This option selects the core processor variant.
698 Select either big-endian (-EB) or little-endian (-EL) output.
703 The following options are available when @value{AS} is configured for the ARM
707 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
708 Specify which ARM processor variant is the target.
709 @item -march=@var{architecture}[+@var{extension}@dots{}]
710 Specify which ARM architecture variant is used by the target.
711 @item -mfpu=@var{floating-point-format}
712 Select which Floating Point architecture is the target.
713 @item -mfloat-abi=@var{abi}
714 Select which floating point ABI is in use.
716 Enable Thumb only instruction decoding.
717 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
718 Select which procedure calling convention is in use.
720 Select either big-endian (-EB) or little-endian (-EL) output.
721 @item -mthumb-interwork
722 Specify that the code has been generated with interworking between Thumb and
725 Specify that PIC code has been generated.
730 The following options are available when @value{AS} is configured for
731 the Blackfin processor family.
734 @item -mcpu=@var{processor}@r{[}-@var{sirevision}@r{]}
735 This option specifies the target processor. The optional @var{sirevision}
736 is not used in assembler.
738 Assemble for the FDPIC ABI.
739 @item -mno-fdpic/-mnopic
745 See the info pages for documentation of the CRIS-specific options.
749 The following options are available when @value{AS} is configured for
752 @cindex D10V optimization
753 @cindex optimization, D10V
755 Optimize output by parallelizing instructions.
760 The following options are available when @value{AS} is configured for a D30V
763 @cindex D30V optimization
764 @cindex optimization, D30V
766 Optimize output by parallelizing instructions.
770 Warn when nops are generated.
772 @cindex D30V nops after 32-bit multiply
774 Warn when a nop after a 32-bit multiply instruction is generated.
779 The following options are available when @value{AS} is configured for the
780 Intel 80960 processor.
783 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
784 Specify which variant of the 960 architecture is the target.
787 Add code to collect statistics about branches taken.
790 Do not alter compare-and-branch instructions for long displacements;
797 The following options are available when @value{AS} is configured for the
803 Specifies that the extended IP2022 instructions are allowed.
806 Restores the default behaviour, which restricts the permitted instructions to
807 just the basic IP2022 ones.
813 The following options are available when @value{AS} is configured for the
814 Renesas M32C and M16C processors.
819 Assemble M32C instructions.
822 Assemble M16C instructions (the default).
825 Enable support for link-time relaxations.
828 Support H'00 style hex constants in addition to 0x00 style.
834 The following options are available when @value{AS} is configured for the
835 Renesas M32R (formerly Mitsubishi M32R) series.
840 Specify which processor in the M32R family is the target. The default
841 is normally the M32R, but this option changes it to the M32RX.
843 @item --warn-explicit-parallel-conflicts or --Wp
844 Produce warning messages when questionable parallel constructs are
847 @item --no-warn-explicit-parallel-conflicts or --Wnp
848 Do not produce warning messages when questionable parallel constructs are
855 The following options are available when @value{AS} is configured for the
856 Motorola 68000 series.
861 Shorten references to undefined symbols, to one word instead of two.
863 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
864 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
865 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
866 Specify what processor in the 68000 family is the target. The default
867 is normally the 68020, but this can be changed at configuration time.
869 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
870 The target machine does (or does not) have a floating-point coprocessor.
871 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
872 the basic 68000 is not compatible with the 68881, a combination of the
873 two can be specified, since it's possible to do emulation of the
874 coprocessor instructions with the main processor.
876 @item -m68851 | -mno-68851
877 The target machine does (or does not) have a memory-management
878 unit coprocessor. The default is to assume an MMU for 68020 and up.
885 For details about the PDP-11 machine dependent features options,
886 see @ref{PDP-11-Options}.
889 @item -mpic | -mno-pic
890 Generate position-independent (or position-dependent) code. The
891 default is @option{-mpic}.
894 @itemx -mall-extensions
895 Enable all instruction set extensions. This is the default.
897 @item -mno-extensions
898 Disable all instruction set extensions.
900 @item -m@var{extension} | -mno-@var{extension}
901 Enable (or disable) a particular instruction set extension.
904 Enable the instruction set extensions supported by a particular CPU, and
905 disable all other extensions.
907 @item -m@var{machine}
908 Enable the instruction set extensions supported by a particular machine
909 model, and disable all other extensions.
915 The following options are available when @value{AS} is configured for
916 a picoJava processor.
920 @cindex PJ endianness
921 @cindex endianness, PJ
922 @cindex big endian output, PJ
924 Generate ``big endian'' format output.
926 @cindex little endian output, PJ
928 Generate ``little endian'' format output.
934 The following options are available when @value{AS} is configured for the
935 Motorola 68HC11 or 68HC12 series.
939 @item -m68hc11 | -m68hc12 | -m68hcs12
940 Specify what processor is the target. The default is
941 defined by the configuration option when building the assembler.
944 Specify to use the 16-bit integer ABI.
947 Specify to use the 32-bit integer ABI.
950 Specify to use the 32-bit double ABI.
953 Specify to use the 64-bit double ABI.
955 @item --force-long-branches
956 Relative branches are turned into absolute ones. This concerns
957 conditional branches, unconditional branches and branches to a
960 @item -S | --short-branches
961 Do not turn relative branches into absolute ones
962 when the offset is out of range.
964 @item --strict-direct-mode
965 Do not turn the direct addressing mode into extended addressing mode
966 when the instruction does not support direct addressing mode.
968 @item --print-insn-syntax
969 Print the syntax of instruction in case of error.
971 @item --print-opcodes
972 print the list of instructions with syntax and then exit.
974 @item --generate-example
975 print an example of instruction for each possible instruction and then exit.
976 This option is only useful for testing @command{@value{AS}}.
982 The following options are available when @command{@value{AS}} is configured
983 for the SPARC architecture:
986 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
987 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
988 Explicitly select a variant of the SPARC architecture.
990 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
991 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
993 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
994 UltraSPARC extensions.
996 @item -xarch=v8plus | -xarch=v8plusa
997 For compatibility with the Solaris v9 assembler. These options are
998 equivalent to -Av8plus and -Av8plusa, respectively.
1001 Warn when the assembler switches to another architecture.
1006 The following options are available when @value{AS} is configured for the 'c54x
1011 Enable extended addressing mode. All addresses and relocations will assume
1012 extended addressing (usually 23 bits).
1013 @item -mcpu=@var{CPU_VERSION}
1014 Sets the CPU version being compiled for.
1015 @item -merrors-to-file @var{FILENAME}
1016 Redirect error output to a file, for broken systems which don't support such
1017 behaviour in the shell.
1022 The following options are available when @value{AS} is configured for
1023 a @sc{mips} processor.
1027 This option sets the largest size of an object that can be referenced
1028 implicitly with the @code{gp} register. It is only accepted for targets that
1029 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
1031 @cindex MIPS endianness
1032 @cindex endianness, MIPS
1033 @cindex big endian output, MIPS
1035 Generate ``big endian'' format output.
1037 @cindex little endian output, MIPS
1039 Generate ``little endian'' format output.
1051 Generate code for a particular @sc{mips} Instruction Set Architecture level.
1052 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
1053 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
1054 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
1055 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and
1057 correspond to generic
1058 @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64},
1059 and @samp{MIPS64 Release 2}
1060 ISA processors, respectively.
1062 @item -march=@var{CPU}
1063 Generate code for a particular @sc{mips} cpu.
1065 @item -mtune=@var{cpu}
1066 Schedule and tune for a particular @sc{mips} cpu.
1070 Cause nops to be inserted if the read of the destination register
1071 of an mfhi or mflo instruction occurs in the following two instructions.
1075 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
1076 section instead of the standard ELF .stabs sections.
1080 Control generation of @code{.pdr} sections.
1084 The register sizes are normally inferred from the ISA and ABI, but these
1085 flags force a certain group of registers to be treated as 32 bits wide at
1086 all times. @samp{-mgp32} controls the size of general-purpose registers
1087 and @samp{-mfp32} controls the size of floating-point registers.
1091 Generate code for the MIPS 16 processor. This is equivalent to putting
1092 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
1093 turns off this option.
1096 @itemx -mno-smartmips
1097 Enables the SmartMIPS extension to the MIPS32 instruction set. This is
1098 equivalent to putting @code{.set smartmips} at the start of the assembly file.
1099 @samp{-mno-smartmips} turns off this option.
1103 Generate code for the MIPS-3D Application Specific Extension.
1104 This tells the assembler to accept MIPS-3D instructions.
1105 @samp{-no-mips3d} turns off this option.
1109 Generate code for the MDMX Application Specific Extension.
1110 This tells the assembler to accept MDMX instructions.
1111 @samp{-no-mdmx} turns off this option.
1115 Generate code for the DSP Release 1 Application Specific Extension.
1116 This tells the assembler to accept DSP Release 1 instructions.
1117 @samp{-mno-dsp} turns off this option.
1121 Generate code for the DSP Release 2 Application Specific Extension.
1122 This option implies -mdsp.
1123 This tells the assembler to accept DSP Release 2 instructions.
1124 @samp{-mno-dspr2} turns off this option.
1128 Generate code for the MT Application Specific Extension.
1129 This tells the assembler to accept MT instructions.
1130 @samp{-mno-mt} turns off this option.
1132 @item --construct-floats
1133 @itemx --no-construct-floats
1134 The @samp{--no-construct-floats} option disables the construction of
1135 double width floating point constants by loading the two halves of the
1136 value into the two single width floating point registers that make up
1137 the double width register. By default @samp{--construct-floats} is
1138 selected, allowing construction of these floating point constants.
1141 @item --emulation=@var{name}
1142 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
1143 for some other target, in all respects, including output format (choosing
1144 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
1145 debugging information or store symbol table information, and default
1146 endianness. The available configuration names are: @samp{mipsecoff},
1147 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
1148 @samp{mipsbelf}. The first two do not alter the default endianness from that
1149 of the primary target for which the assembler was configured; the others change
1150 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
1151 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
1152 selection in any case.
1154 This option is currently supported only when the primary target
1155 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
1156 Furthermore, the primary target or others specified with
1157 @samp{--enable-targets=@dots{}} at configuration time must include support for
1158 the other format, if both are to be available. For example, the Irix 5
1159 configuration includes support for both.
1161 Eventually, this option will support more configurations, with more
1162 fine-grained control over the assembler's behavior, and will be supported for
1166 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1173 Control how to deal with multiplication overflow and division by zero.
1174 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1175 (and only work for Instruction Set Architecture level 2 and higher);
1176 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1180 When this option is used, @command{@value{AS}} will issue a warning every
1181 time it generates a nop instruction from a macro.
1186 The following options are available when @value{AS} is configured for
1192 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1193 The command line option @samp{-nojsri2bsr} can be used to disable it.
1197 Enable or disable the silicon filter behaviour. By default this is disabled.
1198 The default can be overridden by the @samp{-sifilter} command line option.
1201 Alter jump instructions for long displacements.
1203 @item -mcpu=[210|340]
1204 Select the cpu type on the target hardware. This controls which instructions
1208 Assemble for a big endian target.
1211 Assemble for a little endian target.
1217 See the info pages for documentation of the MMIX-specific options.
1221 See the info pages for documentation of the RX-specific options.
1225 The following options are available when @value{AS} is configured for the s390
1231 Select the word size, either 31/32 bits or 64 bits.
1234 Select the architecture mode, either the Enterprise System
1235 Architecture (esa) or the z/Architecture mode (zarch).
1236 @item -march=@var{processor}
1237 Specify which s390 processor variant is the target, @samp{g6}, @samp{g6},
1238 @samp{z900}, @samp{z990}, @samp{z9-109}, @samp{z9-ec}, or @samp{z10}.
1240 @itemx -mno-regnames
1241 Allow or disallow symbolic names for registers.
1242 @item -mwarn-areg-zero
1243 Warn whenever the operand for a base or index register has been specified
1244 but evaluates to zero.
1249 The following options are available when @value{AS} is configured for
1250 an Xtensa processor.
1253 @item --text-section-literals | --no-text-section-literals
1254 With @option{--text-@-section-@-literals}, literal pools are interspersed
1255 in the text section. The default is
1256 @option{--no-@-text-@-section-@-literals}, which places literals in a
1257 separate section in the output file. These options only affect literals
1258 referenced via PC-relative @code{L32R} instructions; literals for
1259 absolute mode @code{L32R} instructions are handled separately.
1261 @item --absolute-literals | --no-absolute-literals
1262 Indicate to the assembler whether @code{L32R} instructions use absolute
1263 or PC-relative addressing. The default is to assume absolute addressing
1264 if the Xtensa processor includes the absolute @code{L32R} addressing
1265 option. Otherwise, only the PC-relative @code{L32R} mode can be used.
1267 @item --target-align | --no-target-align
1268 Enable or disable automatic alignment to reduce branch penalties at the
1269 expense of some code density. The default is @option{--target-@-align}.
1271 @item --longcalls | --no-longcalls
1272 Enable or disable transformation of call instructions to allow calls
1273 across a greater range of addresses. The default is
1274 @option{--no-@-longcalls}.
1276 @item --transform | --no-transform
1277 Enable or disable all assembler transformations of Xtensa instructions.
1278 The default is @option{--transform};
1279 @option{--no-transform} should be used only in the rare cases when the
1280 instructions must be exactly as specified in the assembly source.
1282 @item --rename-section @var{oldname}=@var{newname}
1283 When generating output sections, rename the @var{oldname} section to
1289 The following options are available when @value{AS} is configured for
1290 a Z80 family processor.
1293 Assemble for Z80 processor.
1295 Assemble for R800 processor.
1296 @item -ignore-undocumented-instructions
1298 Assemble undocumented Z80 instructions that also work on R800 without warning.
1299 @item -ignore-unportable-instructions
1301 Assemble all undocumented Z80 instructions without warning.
1302 @item -warn-undocumented-instructions
1304 Issue a warning for undocumented Z80 instructions that also work on R800.
1305 @item -warn-unportable-instructions
1307 Issue a warning for undocumented Z80 instructions that do not work on R800.
1308 @item -forbid-undocumented-instructions
1310 Treat all undocumented instructions as errors.
1311 @item -forbid-unportable-instructions
1313 Treat undocumented Z80 instructions that do not work on R800 as errors.
1320 * Manual:: Structure of this Manual
1321 * GNU Assembler:: The GNU Assembler
1322 * Object Formats:: Object File Formats
1323 * Command Line:: Command Line
1324 * Input Files:: Input Files
1325 * Object:: Output (Object) File
1326 * Errors:: Error and Warning Messages
1330 @section Structure of this Manual
1332 @cindex manual, structure and purpose
1333 This manual is intended to describe what you need to know to use
1334 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1335 notation for symbols, constants, and expressions; the directives that
1336 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1339 We also cover special features in the @value{TARGET}
1340 configuration of @command{@value{AS}}, including assembler directives.
1343 This manual also describes some of the machine-dependent features of
1344 various flavors of the assembler.
1347 @cindex machine instructions (not covered)
1348 On the other hand, this manual is @emph{not} intended as an introduction
1349 to programming in assembly language---let alone programming in general!
1350 In a similar vein, we make no attempt to introduce the machine
1351 architecture; we do @emph{not} describe the instruction set, standard
1352 mnemonics, registers or addressing modes that are standard to a
1353 particular architecture.
1355 You may want to consult the manufacturer's
1356 machine architecture manual for this information.
1360 For information on the H8/300 machine instruction set, see @cite{H8/300
1361 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1362 Programming Manual} (Renesas).
1365 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1366 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1367 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1368 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1371 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1375 @c I think this is premature---doc@cygnus.com, 17jan1991
1377 Throughout this manual, we assume that you are running @dfn{GNU},
1378 the portable operating system from the @dfn{Free Software
1379 Foundation, Inc.}. This restricts our attention to certain kinds of
1380 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1381 once this assumption is granted examples and definitions need less
1384 @command{@value{AS}} is part of a team of programs that turn a high-level
1385 human-readable series of instructions into a low-level
1386 computer-readable series of instructions. Different versions of
1387 @command{@value{AS}} are used for different kinds of computer.
1390 @c There used to be a section "Terminology" here, which defined
1391 @c "contents", "byte", "word", and "long". Defining "word" to any
1392 @c particular size is confusing when the .word directive may generate 16
1393 @c bits on one machine and 32 bits on another; in general, for the user
1394 @c version of this manual, none of these terms seem essential to define.
1395 @c They were used very little even in the former draft of the manual;
1396 @c this draft makes an effort to avoid them (except in names of
1400 @section The GNU Assembler
1402 @c man begin DESCRIPTION
1404 @sc{gnu} @command{as} is really a family of assemblers.
1406 This manual describes @command{@value{AS}}, a member of that family which is
1407 configured for the @value{TARGET} architectures.
1409 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1410 should find a fairly similar environment when you use it on another
1411 architecture. Each version has much in common with the others,
1412 including object file formats, most assembler directives (often called
1413 @dfn{pseudo-ops}) and assembler syntax.@refill
1415 @cindex purpose of @sc{gnu} assembler
1416 @command{@value{AS}} is primarily intended to assemble the output of the
1417 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1418 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1419 assemble correctly everything that other assemblers for the same
1420 machine would assemble.
1422 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1425 @c This remark should appear in generic version of manual; assumption
1426 @c here is that generic version sets M680x0.
1427 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1428 assembler for the same architecture; for example, we know of several
1429 incompatible versions of 680x0 assembly language syntax.
1434 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1435 program in one pass of the source file. This has a subtle impact on the
1436 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1438 @node Object Formats
1439 @section Object File Formats
1441 @cindex object file format
1442 The @sc{gnu} assembler can be configured to produce several alternative
1443 object file formats. For the most part, this does not affect how you
1444 write assembly language programs; but directives for debugging symbols
1445 are typically different in different file formats. @xref{Symbol
1446 Attributes,,Symbol Attributes}.
1449 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1450 @value{OBJ-NAME} format object files.
1452 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1454 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1455 @code{b.out} or COFF format object files.
1458 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1459 SOM or ELF format object files.
1464 @section Command Line
1466 @cindex command line conventions
1468 After the program name @command{@value{AS}}, the command line may contain
1469 options and file names. Options may appear in any order, and may be
1470 before, after, or between file names. The order of file names is
1473 @cindex standard input, as input file
1475 @file{--} (two hyphens) by itself names the standard input file
1476 explicitly, as one of the files for @command{@value{AS}} to assemble.
1478 @cindex options, command line
1479 Except for @samp{--} any command line argument that begins with a
1480 hyphen (@samp{-}) is an option. Each option changes the behavior of
1481 @command{@value{AS}}. No option changes the way another option works. An
1482 option is a @samp{-} followed by one or more letters; the case of
1483 the letter is important. All options are optional.
1485 Some options expect exactly one file name to follow them. The file
1486 name may either immediately follow the option's letter (compatible
1487 with older assemblers) or it may be the next command argument (@sc{gnu}
1488 standard). These two command lines are equivalent:
1491 @value{AS} -o my-object-file.o mumble.s
1492 @value{AS} -omy-object-file.o mumble.s
1496 @section Input Files
1499 @cindex source program
1500 @cindex files, input
1501 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1502 describe the program input to one run of @command{@value{AS}}. The program may
1503 be in one or more files; how the source is partitioned into files
1504 doesn't change the meaning of the source.
1506 @c I added "con" prefix to "catenation" just to prove I can overcome my
1507 @c APL training... doc@cygnus.com
1508 The source program is a concatenation of the text in all the files, in the
1511 @c man begin DESCRIPTION
1512 Each time you run @command{@value{AS}} it assembles exactly one source
1513 program. The source program is made up of one or more files.
1514 (The standard input is also a file.)
1516 You give @command{@value{AS}} a command line that has zero or more input file
1517 names. The input files are read (from left file name to right). A
1518 command line argument (in any position) that has no special meaning
1519 is taken to be an input file name.
1521 If you give @command{@value{AS}} no file names it attempts to read one input file
1522 from the @command{@value{AS}} standard input, which is normally your terminal. You
1523 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1526 Use @samp{--} if you need to explicitly name the standard input file
1527 in your command line.
1529 If the source is empty, @command{@value{AS}} produces a small, empty object
1534 @subheading Filenames and Line-numbers
1536 @cindex input file linenumbers
1537 @cindex line numbers, in input files
1538 There are two ways of locating a line in the input file (or files) and
1539 either may be used in reporting error messages. One way refers to a line
1540 number in a physical file; the other refers to a line number in a
1541 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1543 @dfn{Physical files} are those files named in the command line given
1544 to @command{@value{AS}}.
1546 @dfn{Logical files} are simply names declared explicitly by assembler
1547 directives; they bear no relation to physical files. Logical file names help
1548 error messages reflect the original source file, when @command{@value{AS}} source
1549 is itself synthesized from other files. @command{@value{AS}} understands the
1550 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1551 @ref{File,,@code{.file}}.
1554 @section Output (Object) File
1560 Every time you run @command{@value{AS}} it produces an output file, which is
1561 your assembly language program translated into numbers. This file
1562 is the object file. Its default name is
1570 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1572 You can give it another name by using the @option{-o} option. Conventionally,
1573 object file names end with @file{.o}. The default name is used for historical
1574 reasons: older assemblers were capable of assembling self-contained programs
1575 directly into a runnable program. (For some formats, this isn't currently
1576 possible, but it can be done for the @code{a.out} format.)
1580 The object file is meant for input to the linker @code{@value{LD}}. It contains
1581 assembled program code, information to help @code{@value{LD}} integrate
1582 the assembled program into a runnable file, and (optionally) symbolic
1583 information for the debugger.
1585 @c link above to some info file(s) like the description of a.out.
1586 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1589 @section Error and Warning Messages
1591 @c man begin DESCRIPTION
1593 @cindex error messages
1594 @cindex warning messages
1595 @cindex messages from assembler
1596 @command{@value{AS}} may write warnings and error messages to the standard error
1597 file (usually your terminal). This should not happen when a compiler
1598 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1599 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1600 grave problem that stops the assembly.
1604 @cindex format of warning messages
1605 Warning messages have the format
1608 file_name:@b{NNN}:Warning Message Text
1612 @cindex line numbers, in warnings/errors
1613 (where @b{NNN} is a line number). If a logical file name has been given
1614 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1615 the current input file is used. If a logical line number was given
1617 (@pxref{Line,,@code{.line}})
1619 then it is used to calculate the number printed,
1620 otherwise the actual line in the current source file is printed. The
1621 message text is intended to be self explanatory (in the grand Unix
1624 @cindex format of error messages
1625 Error messages have the format
1627 file_name:@b{NNN}:FATAL:Error Message Text
1629 The file name and line number are derived as for warning
1630 messages. The actual message text may be rather less explanatory
1631 because many of them aren't supposed to happen.
1634 @chapter Command-Line Options
1636 @cindex options, all versions of assembler
1637 This chapter describes command-line options available in @emph{all}
1638 versions of the @sc{gnu} assembler; see @ref{Machine Dependencies},
1639 for options specific
1641 to the @value{TARGET} target.
1644 to particular machine architectures.
1647 @c man begin DESCRIPTION
1649 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
1650 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1651 The assembler arguments must be separated from each other (and the @samp{-Wa})
1652 by commas. For example:
1655 gcc -c -g -O -Wa,-alh,-L file.c
1659 This passes two options to the assembler: @samp{-alh} (emit a listing to
1660 standard output with high-level and assembly source) and @samp{-L} (retain
1661 local symbols in the symbol table).
1663 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1664 command-line options are automatically passed to the assembler by the compiler.
1665 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1666 precisely what options it passes to each compilation pass, including the
1672 * a:: -a[cdghlns] enable listings
1673 * alternate:: --alternate enable alternate macro syntax
1674 * D:: -D for compatibility
1675 * f:: -f to work faster
1676 * I:: -I for .include search path
1677 @ifclear DIFF-TBL-KLUGE
1678 * K:: -K for compatibility
1680 @ifset DIFF-TBL-KLUGE
1681 * K:: -K for difference tables
1684 * L:: -L to retain local symbols
1685 * listing:: --listing-XXX to configure listing output
1686 * M:: -M or --mri to assemble in MRI compatibility mode
1687 * MD:: --MD for dependency tracking
1688 * o:: -o to name the object file
1689 * R:: -R to join data and text sections
1690 * statistics:: --statistics to see statistics about assembly
1691 * traditional-format:: --traditional-format for compatible output
1692 * v:: -v to announce version
1693 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1694 * Z:: -Z to make object file even after errors
1698 @section Enable Listings: @option{-a[cdghlns]}
1708 @cindex listings, enabling
1709 @cindex assembly listings, enabling
1711 These options enable listing output from the assembler. By itself,
1712 @samp{-a} requests high-level, assembly, and symbols listing.
1713 You can use other letters to select specific options for the list:
1714 @samp{-ah} requests a high-level language listing,
1715 @samp{-al} requests an output-program assembly listing, and
1716 @samp{-as} requests a symbol table listing.
1717 High-level listings require that a compiler debugging option like
1718 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1721 Use the @samp{-ag} option to print a first section with general assembly
1722 information, like @value{AS} version, switches passed, or time stamp.
1724 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1725 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1726 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1727 omitted from the listing.
1729 Use the @samp{-ad} option to omit debugging directives from the
1732 Once you have specified one of these options, you can further control
1733 listing output and its appearance using the directives @code{.list},
1734 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1736 The @samp{-an} option turns off all forms processing.
1737 If you do not request listing output with one of the @samp{-a} options, the
1738 listing-control directives have no effect.
1740 The letters after @samp{-a} may be combined into one option,
1741 @emph{e.g.}, @samp{-aln}.
1743 Note if the assembler source is coming from the standard input (e.g.,
1745 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1746 is being used) then the listing will not contain any comments or preprocessor
1747 directives. This is because the listing code buffers input source lines from
1748 stdin only after they have been preprocessed by the assembler. This reduces
1749 memory usage and makes the code more efficient.
1752 @section @option{--alternate}
1755 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
1758 @section @option{-D}
1761 This option has no effect whatsoever, but it is accepted to make it more
1762 likely that scripts written for other assemblers also work with
1763 @command{@value{AS}}.
1766 @section Work Faster: @option{-f}
1769 @cindex trusted compiler
1770 @cindex faster processing (@option{-f})
1771 @samp{-f} should only be used when assembling programs written by a
1772 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1773 and comment preprocessing on
1774 the input file(s) before assembling them. @xref{Preprocessing,
1778 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1779 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1784 @section @code{.include} Search Path: @option{-I} @var{path}
1786 @kindex -I @var{path}
1787 @cindex paths for @code{.include}
1788 @cindex search path for @code{.include}
1789 @cindex @code{include} directive search path
1790 Use this option to add a @var{path} to the list of directories
1791 @command{@value{AS}} searches for files specified in @code{.include}
1792 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1793 many times as necessary to include a variety of paths. The current
1794 working directory is always searched first; after that, @command{@value{AS}}
1795 searches any @samp{-I} directories in the same order as they were
1796 specified (left to right) on the command line.
1799 @section Difference Tables: @option{-K}
1802 @ifclear DIFF-TBL-KLUGE
1803 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1804 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1805 where it can be used to warn when the assembler alters the machine code
1806 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1807 family does not have the addressing limitations that sometimes lead to this
1808 alteration on other platforms.
1811 @ifset DIFF-TBL-KLUGE
1812 @cindex difference tables, warning
1813 @cindex warning for altered difference tables
1814 @command{@value{AS}} sometimes alters the code emitted for directives of the
1815 form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}.
1816 You can use the @samp{-K} option if you want a warning issued when this
1821 @section Include Local Symbols: @option{-L}
1824 @cindex local symbols, retaining in output
1825 Symbols beginning with system-specific local label prefixes, typically
1826 @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are
1827 called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see
1828 such symbols when debugging, because they are intended for the use of
1829 programs (like compilers) that compose assembler programs, not for your
1830 notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard
1831 such symbols, so you do not normally debug with them.
1833 This option tells @command{@value{AS}} to retain those local symbols
1834 in the object file. Usually if you do this you also tell the linker
1835 @code{@value{LD}} to preserve those symbols.
1838 @section Configuring listing output: @option{--listing}
1840 The listing feature of the assembler can be enabled via the command line switch
1841 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1842 hex dump of the corresponding locations in the output object file, and displays
1843 them as a listing file. The format of this listing can be controlled by
1844 directives inside the assembler source (i.e., @code{.list} (@pxref{List}),
1845 @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}),
1846 @code{.psize} (@pxref{Psize}), and
1847 @code{.eject} (@pxref{Eject}) and also by the following switches:
1850 @item --listing-lhs-width=@samp{number}
1851 @kindex --listing-lhs-width
1852 @cindex Width of first line disassembly output
1853 Sets the maximum width, in words, of the first line of the hex byte dump. This
1854 dump appears on the left hand side of the listing output.
1856 @item --listing-lhs-width2=@samp{number}
1857 @kindex --listing-lhs-width2
1858 @cindex Width of continuation lines of disassembly output
1859 Sets the maximum width, in words, of any further lines of the hex byte dump for
1860 a given input source line. If this value is not specified, it defaults to being
1861 the same as the value specified for @samp{--listing-lhs-width}. If neither
1862 switch is used the default is to one.
1864 @item --listing-rhs-width=@samp{number}
1865 @kindex --listing-rhs-width
1866 @cindex Width of source line output
1867 Sets the maximum width, in characters, of the source line that is displayed
1868 alongside the hex dump. The default value for this parameter is 100. The
1869 source line is displayed on the right hand side of the listing output.
1871 @item --listing-cont-lines=@samp{number}
1872 @kindex --listing-cont-lines
1873 @cindex Maximum number of continuation lines
1874 Sets the maximum number of continuation lines of hex dump that will be
1875 displayed for a given single line of source input. The default value is 4.
1879 @section Assemble in MRI Compatibility Mode: @option{-M}
1882 @cindex MRI compatibility mode
1883 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1884 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1885 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1886 configured target) assembler from Microtec Research. The exact nature of the
1887 MRI syntax will not be documented here; see the MRI manuals for more
1888 information. Note in particular that the handling of macros and macro
1889 arguments is somewhat different. The purpose of this option is to permit
1890 assembling existing MRI assembler code using @command{@value{AS}}.
1892 The MRI compatibility is not complete. Certain operations of the MRI assembler
1893 depend upon its object file format, and can not be supported using other object
1894 file formats. Supporting these would require enhancing each object file format
1895 individually. These are:
1898 @item global symbols in common section
1900 The m68k MRI assembler supports common sections which are merged by the linker.
1901 Other object file formats do not support this. @command{@value{AS}} handles
1902 common sections by treating them as a single common symbol. It permits local
1903 symbols to be defined within a common section, but it can not support global
1904 symbols, since it has no way to describe them.
1906 @item complex relocations
1908 The MRI assemblers support relocations against a negated section address, and
1909 relocations which combine the start addresses of two or more sections. These
1910 are not support by other object file formats.
1912 @item @code{END} pseudo-op specifying start address
1914 The MRI @code{END} pseudo-op permits the specification of a start address.
1915 This is not supported by other object file formats. The start address may
1916 instead be specified using the @option{-e} option to the linker, or in a linker
1919 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1921 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1922 name to the output file. This is not supported by other object file formats.
1924 @item @code{ORG} pseudo-op
1926 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1927 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1928 which changes the location within the current section. Absolute sections are
1929 not supported by other object file formats. The address of a section may be
1930 assigned within a linker script.
1933 There are some other features of the MRI assembler which are not supported by
1934 @command{@value{AS}}, typically either because they are difficult or because they
1935 seem of little consequence. Some of these may be supported in future releases.
1939 @item EBCDIC strings
1941 EBCDIC strings are not supported.
1943 @item packed binary coded decimal
1945 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1946 and @code{DCB.P} pseudo-ops are not supported.
1948 @item @code{FEQU} pseudo-op
1950 The m68k @code{FEQU} pseudo-op is not supported.
1952 @item @code{NOOBJ} pseudo-op
1954 The m68k @code{NOOBJ} pseudo-op is not supported.
1956 @item @code{OPT} branch control options
1958 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1959 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1960 relaxes all branches, whether forward or backward, to an appropriate size, so
1961 these options serve no purpose.
1963 @item @code{OPT} list control options
1965 The following m68k @code{OPT} list control options are ignored: @code{C},
1966 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1967 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1969 @item other @code{OPT} options
1971 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1972 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1974 @item @code{OPT} @code{D} option is default
1976 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1977 @code{OPT NOD} may be used to turn it off.
1979 @item @code{XREF} pseudo-op.
1981 The m68k @code{XREF} pseudo-op is ignored.
1983 @item @code{.debug} pseudo-op
1985 The i960 @code{.debug} pseudo-op is not supported.
1987 @item @code{.extended} pseudo-op
1989 The i960 @code{.extended} pseudo-op is not supported.
1991 @item @code{.list} pseudo-op.
1993 The various options of the i960 @code{.list} pseudo-op are not supported.
1995 @item @code{.optimize} pseudo-op
1997 The i960 @code{.optimize} pseudo-op is not supported.
1999 @item @code{.output} pseudo-op
2001 The i960 @code{.output} pseudo-op is not supported.
2003 @item @code{.setreal} pseudo-op
2005 The i960 @code{.setreal} pseudo-op is not supported.
2010 @section Dependency Tracking: @option{--MD}
2013 @cindex dependency tracking
2016 @command{@value{AS}} can generate a dependency file for the file it creates. This
2017 file consists of a single rule suitable for @code{make} describing the
2018 dependencies of the main source file.
2020 The rule is written to the file named in its argument.
2022 This feature is used in the automatic updating of makefiles.
2025 @section Name the Object File: @option{-o}
2028 @cindex naming object file
2029 @cindex object file name
2030 There is always one object file output when you run @command{@value{AS}}. By
2031 default it has the name
2034 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
2048 You use this option (which takes exactly one filename) to give the
2049 object file a different name.
2051 Whatever the object file is called, @command{@value{AS}} overwrites any
2052 existing file of the same name.
2055 @section Join Data and Text Sections: @option{-R}
2058 @cindex data and text sections, joining
2059 @cindex text and data sections, joining
2060 @cindex joining text and data sections
2061 @cindex merging text and data sections
2062 @option{-R} tells @command{@value{AS}} to write the object file as if all
2063 data-section data lives in the text section. This is only done at
2064 the very last moment: your binary data are the same, but data
2065 section parts are relocated differently. The data section part of
2066 your object file is zero bytes long because all its bytes are
2067 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
2069 When you specify @option{-R} it would be possible to generate shorter
2070 address displacements (because we do not have to cross between text and
2071 data section). We refrain from doing this simply for compatibility with
2072 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
2075 When @command{@value{AS}} is configured for COFF or ELF output,
2076 this option is only useful if you use sections named @samp{.text} and
2081 @option{-R} is not supported for any of the HPPA targets. Using
2082 @option{-R} generates a warning from @command{@value{AS}}.
2086 @section Display Assembly Statistics: @option{--statistics}
2088 @kindex --statistics
2089 @cindex statistics, about assembly
2090 @cindex time, total for assembly
2091 @cindex space used, maximum for assembly
2092 Use @samp{--statistics} to display two statistics about the resources used by
2093 @command{@value{AS}}: the maximum amount of space allocated during the assembly
2094 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
2097 @node traditional-format
2098 @section Compatible Output: @option{--traditional-format}
2100 @kindex --traditional-format
2101 For some targets, the output of @command{@value{AS}} is different in some ways
2102 from the output of some existing assembler. This switch requests
2103 @command{@value{AS}} to use the traditional format instead.
2105 For example, it disables the exception frame optimizations which
2106 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
2109 @section Announce Version: @option{-v}
2113 @cindex assembler version
2114 @cindex version of assembler
2115 You can find out what version of as is running by including the
2116 option @samp{-v} (which you can also spell as @samp{-version}) on the
2120 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
2122 @command{@value{AS}} should never give a warning or error message when
2123 assembling compiler output. But programs written by people often
2124 cause @command{@value{AS}} to give a warning that a particular assumption was
2125 made. All such warnings are directed to the standard error file.
2129 @cindex suppressing warnings
2130 @cindex warnings, suppressing
2131 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
2132 This only affects the warning messages: it does not change any particular of
2133 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
2136 @kindex --fatal-warnings
2137 @cindex errors, caused by warnings
2138 @cindex warnings, causing error
2139 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
2140 files that generate warnings to be in error.
2143 @cindex warnings, switching on
2144 You can switch these options off again by specifying @option{--warn}, which
2145 causes warnings to be output as usual.
2148 @section Generate Object File in Spite of Errors: @option{-Z}
2149 @cindex object file, after errors
2150 @cindex errors, continuing after
2151 After an error message, @command{@value{AS}} normally produces no output. If for
2152 some reason you are interested in object file output even after
2153 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
2154 option. If there are any errors, @command{@value{AS}} continues anyways, and
2155 writes an object file after a final warning message of the form @samp{@var{n}
2156 errors, @var{m} warnings, generating bad object file.}
2161 @cindex machine-independent syntax
2162 @cindex syntax, machine-independent
2163 This chapter describes the machine-independent syntax allowed in a
2164 source file. @command{@value{AS}} syntax is similar to what many other
2165 assemblers use; it is inspired by the BSD 4.2
2170 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
2174 * Preprocessing:: Preprocessing
2175 * Whitespace:: Whitespace
2176 * Comments:: Comments
2177 * Symbol Intro:: Symbols
2178 * Statements:: Statements
2179 * Constants:: Constants
2183 @section Preprocessing
2185 @cindex preprocessing
2186 The @command{@value{AS}} internal preprocessor:
2188 @cindex whitespace, removed by preprocessor
2190 adjusts and removes extra whitespace. It leaves one space or tab before
2191 the keywords on a line, and turns any other whitespace on the line into
2194 @cindex comments, removed by preprocessor
2196 removes all comments, replacing them with a single space, or an
2197 appropriate number of newlines.
2199 @cindex constants, converted by preprocessor
2201 converts character constants into the appropriate numeric values.
2204 It does not do macro processing, include file handling, or
2205 anything else you may get from your C compiler's preprocessor. You can
2206 do include file processing with the @code{.include} directive
2207 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2208 to get other ``CPP'' style preprocessing by giving the input file a
2209 @samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of
2210 Output, gcc.info, Using GNU CC}.
2212 Excess whitespace, comments, and character constants
2213 cannot be used in the portions of the input text that are not
2216 @cindex turning preprocessing on and off
2217 @cindex preprocessing, turning on and off
2220 If the first line of an input file is @code{#NO_APP} or if you use the
2221 @samp{-f} option, whitespace and comments are not removed from the input file.
2222 Within an input file, you can ask for whitespace and comment removal in
2223 specific portions of the by putting a line that says @code{#APP} before the
2224 text that may contain whitespace or comments, and putting a line that says
2225 @code{#NO_APP} after this text. This feature is mainly intend to support
2226 @code{asm} statements in compilers whose output is otherwise free of comments
2233 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2234 Whitespace is used to separate symbols, and to make programs neater for
2235 people to read. Unless within character constants
2236 (@pxref{Characters,,Character Constants}), any whitespace means the same
2237 as exactly one space.
2243 There are two ways of rendering comments to @command{@value{AS}}. In both
2244 cases the comment is equivalent to one space.
2246 Anything from @samp{/*} through the next @samp{*/} is a comment.
2247 This means you may not nest these comments.
2251 The only way to include a newline ('\n') in a comment
2252 is to use this sort of comment.
2255 /* This sort of comment does not nest. */
2258 @cindex line comment character
2259 Anything from the @dfn{line comment} character to the next newline
2260 is considered a comment and is ignored. The line comment character is
2262 @samp{;} on the ARC;
2265 @samp{@@} on the ARM;
2268 @samp{;} for the H8/300 family;
2271 @samp{;} for the HPPA;
2274 @samp{#} on the i386 and x86-64;
2277 @samp{#} on the i960;
2280 @samp{;} for the PDP-11;
2283 @samp{;} for picoJava;
2286 @samp{#} for Motorola PowerPC;
2289 @samp{#} for IBM S/390;
2292 @samp{#} for the Sunplus SCORE;
2295 @samp{!} for the Renesas / SuperH SH;
2298 @samp{!} on the SPARC;
2301 @samp{#} on the ip2k;
2304 @samp{#} on the m32c;
2307 @samp{#} on the m32r;
2310 @samp{|} on the 680x0;
2313 @samp{#} on the 68HC11 and 68HC12;
2319 @samp{#} on the Vax;
2322 @samp{;} for the Z80;
2325 @samp{!} for the Z8000;
2328 @samp{#} on the V850;
2331 @samp{#} for Xtensa systems;
2333 see @ref{Machine Dependencies}. @refill
2334 @c FIXME What about i860?
2337 On some machines there are two different line comment characters. One
2338 character only begins a comment if it is the first non-whitespace character on
2339 a line, while the other always begins a comment.
2343 The V850 assembler also supports a double dash as starting a comment that
2344 extends to the end of the line.
2350 @cindex lines starting with @code{#}
2351 @cindex logical line numbers
2352 To be compatible with past assemblers, lines that begin with @samp{#} have a
2353 special interpretation. Following the @samp{#} should be an absolute
2354 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2355 line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a
2356 new logical file name. The rest of the line, if any, should be whitespace.
2358 If the first non-whitespace characters on the line are not numeric,
2359 the line is ignored. (Just like a comment.)
2362 # This is an ordinary comment.
2363 # 42-6 "new_file_name" # New logical file name
2364 # This is logical line # 36.
2366 This feature is deprecated, and may disappear from future versions
2367 of @command{@value{AS}}.
2372 @cindex characters used in symbols
2373 @ifclear SPECIAL-SYMS
2374 A @dfn{symbol} is one or more characters chosen from the set of all
2375 letters (both upper and lower case), digits and the three characters
2381 A @dfn{symbol} is one or more characters chosen from the set of all
2382 letters (both upper and lower case), digits and the three characters
2383 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2389 On most machines, you can also use @code{$} in symbol names; exceptions
2390 are noted in @ref{Machine Dependencies}.
2392 No symbol may begin with a digit. Case is significant.
2393 There is no length limit: all characters are significant. Symbols are
2394 delimited by characters not in that set, or by the beginning of a file
2395 (since the source program must end with a newline, the end of a file is
2396 not a possible symbol delimiter). @xref{Symbols}.
2397 @cindex length of symbols
2402 @cindex statements, structure of
2403 @cindex line separator character
2404 @cindex statement separator character
2406 @ifclear abnormal-separator
2407 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2408 semicolon (@samp{;}). The newline or semicolon is considered part of
2409 the preceding statement. Newlines and semicolons within character
2410 constants are an exception: they do not end statements.
2412 @ifset abnormal-separator
2414 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2415 point (@samp{!}). The newline or exclamation point is considered part of the
2416 preceding statement. Newlines and exclamation points within character
2417 constants are an exception: they do not end statements.
2420 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2421 H8/300) a dollar sign (@samp{$}); or (for the Renesas-SH) a semicolon
2422 (@samp{;}). The newline or separator character is considered part of
2423 the preceding statement. Newlines and separators within character
2424 constants are an exception: they do not end statements.
2429 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2430 separator character. (The line separator is usually @samp{;}, unless this
2431 conflicts with the comment character; see @ref{Machine Dependencies}.) The
2432 newline or separator character is considered part of the preceding
2433 statement. Newlines and separators within character constants are an
2434 exception: they do not end statements.
2437 @cindex newline, required at file end
2438 @cindex EOF, newline must precede
2439 It is an error to end any statement with end-of-file: the last
2440 character of any input file should be a newline.@refill
2442 An empty statement is allowed, and may include whitespace. It is ignored.
2444 @cindex instructions and directives
2445 @cindex directives and instructions
2446 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2447 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2449 A statement begins with zero or more labels, optionally followed by a
2450 key symbol which determines what kind of statement it is. The key
2451 symbol determines the syntax of the rest of the statement. If the
2452 symbol begins with a dot @samp{.} then the statement is an assembler
2453 directive: typically valid for any computer. If the symbol begins with
2454 a letter the statement is an assembly language @dfn{instruction}: it
2455 assembles into a machine language instruction.
2457 Different versions of @command{@value{AS}} for different computers
2458 recognize different instructions. In fact, the same symbol may
2459 represent a different instruction in a different computer's assembly
2463 @cindex @code{:} (label)
2464 @cindex label (@code{:})
2465 A label is a symbol immediately followed by a colon (@code{:}).
2466 Whitespace before a label or after a colon is permitted, but you may not
2467 have whitespace between a label's symbol and its colon. @xref{Labels}.
2470 For HPPA targets, labels need not be immediately followed by a colon, but
2471 the definition of a label must begin in column zero. This also implies that
2472 only one label may be defined on each line.
2476 label: .directive followed by something
2477 another_label: # This is an empty statement.
2478 instruction operand_1, operand_2, @dots{}
2485 A constant is a number, written so that its value is known by
2486 inspection, without knowing any context. Like this:
2489 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2490 .ascii "Ring the bell\7" # A string constant.
2491 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2492 .float 0f-314159265358979323846264338327\
2493 95028841971.693993751E-40 # - pi, a flonum.
2498 * Characters:: Character Constants
2499 * Numbers:: Number Constants
2503 @subsection Character Constants
2505 @cindex character constants
2506 @cindex constants, character
2507 There are two kinds of character constants. A @dfn{character} stands
2508 for one character in one byte and its value may be used in
2509 numeric expressions. String constants (properly called string
2510 @emph{literals}) are potentially many bytes and their values may not be
2511 used in arithmetic expressions.
2515 * Chars:: Characters
2519 @subsubsection Strings
2521 @cindex string constants
2522 @cindex constants, string
2523 A @dfn{string} is written between double-quotes. It may contain
2524 double-quotes or null characters. The way to get special characters
2525 into a string is to @dfn{escape} these characters: precede them with
2526 a backslash @samp{\} character. For example @samp{\\} represents
2527 one backslash: the first @code{\} is an escape which tells
2528 @command{@value{AS}} to interpret the second character literally as a backslash
2529 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2530 escape character). The complete list of escapes follows.
2532 @cindex escape codes, character
2533 @cindex character escape codes
2536 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2538 @cindex @code{\b} (backspace character)
2539 @cindex backspace (@code{\b})
2541 Mnemonic for backspace; for ASCII this is octal code 010.
2544 @c Mnemonic for EOText; for ASCII this is octal code 004.
2546 @cindex @code{\f} (formfeed character)
2547 @cindex formfeed (@code{\f})
2549 Mnemonic for FormFeed; for ASCII this is octal code 014.
2551 @cindex @code{\n} (newline character)
2552 @cindex newline (@code{\n})
2554 Mnemonic for newline; for ASCII this is octal code 012.
2557 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2559 @cindex @code{\r} (carriage return character)
2560 @cindex carriage return (@code{\r})
2562 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2565 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2566 @c other assemblers.
2568 @cindex @code{\t} (tab)
2569 @cindex tab (@code{\t})
2571 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2574 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2575 @c @item \x @var{digit} @var{digit} @var{digit}
2576 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2578 @cindex @code{\@var{ddd}} (octal character code)
2579 @cindex octal character code (@code{\@var{ddd}})
2580 @item \ @var{digit} @var{digit} @var{digit}
2581 An octal character code. The numeric code is 3 octal digits.
2582 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2583 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2585 @cindex @code{\@var{xd...}} (hex character code)
2586 @cindex hex character code (@code{\@var{xd...}})
2587 @item \@code{x} @var{hex-digits...}
2588 A hex character code. All trailing hex digits are combined. Either upper or
2589 lower case @code{x} works.
2591 @cindex @code{\\} (@samp{\} character)
2592 @cindex backslash (@code{\\})
2594 Represents one @samp{\} character.
2597 @c Represents one @samp{'} (accent acute) character.
2598 @c This is needed in single character literals
2599 @c (@xref{Characters,,Character Constants}.) to represent
2602 @cindex @code{\"} (doublequote character)
2603 @cindex doublequote (@code{\"})
2605 Represents one @samp{"} character. Needed in strings to represent
2606 this character, because an unescaped @samp{"} would end the string.
2608 @item \ @var{anything-else}
2609 Any other character when escaped by @kbd{\} gives a warning, but
2610 assembles as if the @samp{\} was not present. The idea is that if
2611 you used an escape sequence you clearly didn't want the literal
2612 interpretation of the following character. However @command{@value{AS}} has no
2613 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2614 code and warns you of the fact.
2617 Which characters are escapable, and what those escapes represent,
2618 varies widely among assemblers. The current set is what we think
2619 the BSD 4.2 assembler recognizes, and is a subset of what most C
2620 compilers recognize. If you are in doubt, do not use an escape
2624 @subsubsection Characters
2626 @cindex single character constant
2627 @cindex character, single
2628 @cindex constant, single character
2629 A single character may be written as a single quote immediately
2630 followed by that character. The same escapes apply to characters as
2631 to strings. So if you want to write the character backslash, you
2632 must write @kbd{'\\} where the first @code{\} escapes the second
2633 @code{\}. As you can see, the quote is an acute accent, not a
2634 grave accent. A newline
2636 @ifclear abnormal-separator
2637 (or semicolon @samp{;})
2639 @ifset abnormal-separator
2641 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2646 immediately following an acute accent is taken as a literal character
2647 and does not count as the end of a statement. The value of a character
2648 constant in a numeric expression is the machine's byte-wide code for
2649 that character. @command{@value{AS}} assumes your character code is ASCII:
2650 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2653 @subsection Number Constants
2655 @cindex constants, number
2656 @cindex number constants
2657 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2658 are stored in the target machine. @emph{Integers} are numbers that
2659 would fit into an @code{int} in the C language. @emph{Bignums} are
2660 integers, but they are stored in more than 32 bits. @emph{Flonums}
2661 are floating point numbers, described below.
2664 * Integers:: Integers
2669 * Bit Fields:: Bit Fields
2675 @subsubsection Integers
2677 @cindex constants, integer
2679 @cindex binary integers
2680 @cindex integers, binary
2681 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2682 the binary digits @samp{01}.
2684 @cindex octal integers
2685 @cindex integers, octal
2686 An octal integer is @samp{0} followed by zero or more of the octal
2687 digits (@samp{01234567}).
2689 @cindex decimal integers
2690 @cindex integers, decimal
2691 A decimal integer starts with a non-zero digit followed by zero or
2692 more digits (@samp{0123456789}).
2694 @cindex hexadecimal integers
2695 @cindex integers, hexadecimal
2696 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2697 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2699 Integers have the usual values. To denote a negative integer, use
2700 the prefix operator @samp{-} discussed under expressions
2701 (@pxref{Prefix Ops,,Prefix Operators}).
2704 @subsubsection Bignums
2707 @cindex constants, bignum
2708 A @dfn{bignum} has the same syntax and semantics as an integer
2709 except that the number (or its negative) takes more than 32 bits to
2710 represent in binary. The distinction is made because in some places
2711 integers are permitted while bignums are not.
2714 @subsubsection Flonums
2716 @cindex floating point numbers
2717 @cindex constants, floating point
2719 @cindex precision, floating point
2720 A @dfn{flonum} represents a floating point number. The translation is
2721 indirect: a decimal floating point number from the text is converted by
2722 @command{@value{AS}} to a generic binary floating point number of more than
2723 sufficient precision. This generic floating point number is converted
2724 to a particular computer's floating point format (or formats) by a
2725 portion of @command{@value{AS}} specialized to that computer.
2727 A flonum is written by writing (in order)
2732 (@samp{0} is optional on the HPPA.)
2736 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2738 @kbd{e} is recommended. Case is not important.
2740 @c FIXME: verify if flonum syntax really this vague for most cases
2741 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2742 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2745 On the H8/300, Renesas / SuperH SH,
2746 and AMD 29K architectures, the letter must be
2747 one of the letters @samp{DFPRSX} (in upper or lower case).
2749 On the ARC, the letter must be one of the letters @samp{DFRS}
2750 (in upper or lower case).
2752 On the Intel 960 architecture, the letter must be
2753 one of the letters @samp{DFT} (in upper or lower case).
2755 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2759 One of the letters @samp{DFRS} (in upper or lower case).
2762 One of the letters @samp{DFPRSX} (in upper or lower case).
2765 The letter @samp{E} (upper case only).
2768 One of the letters @samp{DFT} (in upper or lower case).
2773 An optional sign: either @samp{+} or @samp{-}.
2776 An optional @dfn{integer part}: zero or more decimal digits.
2779 An optional @dfn{fractional part}: @samp{.} followed by zero
2780 or more decimal digits.
2783 An optional exponent, consisting of:
2787 An @samp{E} or @samp{e}.
2788 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2789 @c principle this can perfectly well be different on different targets.
2791 Optional sign: either @samp{+} or @samp{-}.
2793 One or more decimal digits.
2798 At least one of the integer part or the fractional part must be
2799 present. The floating point number has the usual base-10 value.
2801 @command{@value{AS}} does all processing using integers. Flonums are computed
2802 independently of any floating point hardware in the computer running
2803 @command{@value{AS}}.
2807 @c Bit fields are written as a general facility but are also controlled
2808 @c by a conditional-compilation flag---which is as of now (21mar91)
2809 @c turned on only by the i960 config of GAS.
2811 @subsubsection Bit Fields
2814 @cindex constants, bit field
2815 You can also define numeric constants as @dfn{bit fields}.
2816 Specify two numbers separated by a colon---
2818 @var{mask}:@var{value}
2821 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2824 The resulting number is then packed
2826 @c this conditional paren in case bit fields turned on elsewhere than 960
2827 (in host-dependent byte order)
2829 into a field whose width depends on which assembler directive has the
2830 bit-field as its argument. Overflow (a result from the bitwise and
2831 requiring more binary digits to represent) is not an error; instead,
2832 more constants are generated, of the specified width, beginning with the
2833 least significant digits.@refill
2835 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2836 @code{.short}, and @code{.word} accept bit-field arguments.
2841 @chapter Sections and Relocation
2846 * Secs Background:: Background
2847 * Ld Sections:: Linker Sections
2848 * As Sections:: Assembler Internal Sections
2849 * Sub-Sections:: Sub-Sections
2853 @node Secs Background
2856 Roughly, a section is a range of addresses, with no gaps; all data
2857 ``in'' those addresses is treated the same for some particular purpose.
2858 For example there may be a ``read only'' section.
2860 @cindex linker, and assembler
2861 @cindex assembler, and linker
2862 The linker @code{@value{LD}} reads many object files (partial programs) and
2863 combines their contents to form a runnable program. When @command{@value{AS}}
2864 emits an object file, the partial program is assumed to start at address 0.
2865 @code{@value{LD}} assigns the final addresses for the partial program, so that
2866 different partial programs do not overlap. This is actually an
2867 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2870 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2871 addresses. These blocks slide to their run-time addresses as rigid
2872 units; their length does not change and neither does the order of bytes
2873 within them. Such a rigid unit is called a @emph{section}. Assigning
2874 run-time addresses to sections is called @dfn{relocation}. It includes
2875 the task of adjusting mentions of object-file addresses so they refer to
2876 the proper run-time addresses.
2878 For the H8/300, and for the Renesas / SuperH SH,
2879 @command{@value{AS}} pads sections if needed to
2880 ensure they end on a word (sixteen bit) boundary.
2883 @cindex standard assembler sections
2884 An object file written by @command{@value{AS}} has at least three sections, any
2885 of which may be empty. These are named @dfn{text}, @dfn{data} and
2890 When it generates COFF or ELF output,
2892 @command{@value{AS}} can also generate whatever other named sections you specify
2893 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2894 If you do not use any directives that place output in the @samp{.text}
2895 or @samp{.data} sections, these sections still exist, but are empty.
2900 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2902 @command{@value{AS}} can also generate whatever other named sections you
2903 specify using the @samp{.space} and @samp{.subspace} directives. See
2904 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2905 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2906 assembler directives.
2909 Additionally, @command{@value{AS}} uses different names for the standard
2910 text, data, and bss sections when generating SOM output. Program text
2911 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2912 BSS into @samp{$BSS$}.
2916 Within the object file, the text section starts at address @code{0}, the
2917 data section follows, and the bss section follows the data section.
2920 When generating either SOM or ELF output files on the HPPA, the text
2921 section starts at address @code{0}, the data section at address
2922 @code{0x4000000}, and the bss section follows the data section.
2925 To let @code{@value{LD}} know which data changes when the sections are
2926 relocated, and how to change that data, @command{@value{AS}} also writes to the
2927 object file details of the relocation needed. To perform relocation
2928 @code{@value{LD}} must know, each time an address in the object
2932 Where in the object file is the beginning of this reference to
2935 How long (in bytes) is this reference?
2937 Which section does the address refer to? What is the numeric value of
2939 (@var{address}) @minus{} (@var{start-address of section})?
2942 Is the reference to an address ``Program-Counter relative''?
2945 @cindex addresses, format of
2946 @cindex section-relative addressing
2947 In fact, every address @command{@value{AS}} ever uses is expressed as
2949 (@var{section}) + (@var{offset into section})
2952 Further, most expressions @command{@value{AS}} computes have this section-relative
2955 (For some object formats, such as SOM for the HPPA, some expressions are
2956 symbol-relative instead.)
2959 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2960 @var{N} into section @var{secname}.''
2962 Apart from text, data and bss sections you need to know about the
2963 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2964 addresses in the absolute section remain unchanged. For example, address
2965 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2966 @code{@value{LD}}. Although the linker never arranges two partial programs'
2967 data sections with overlapping addresses after linking, @emph{by definition}
2968 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2969 part of a program is always the same address when the program is running as
2970 address @code{@{absolute@ 239@}} in any other part of the program.
2972 The idea of sections is extended to the @dfn{undefined} section. Any
2973 address whose section is unknown at assembly time is by definition
2974 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2975 Since numbers are always defined, the only way to generate an undefined
2976 address is to mention an undefined symbol. A reference to a named
2977 common block would be such a symbol: its value is unknown at assembly
2978 time so it has section @emph{undefined}.
2980 By analogy the word @emph{section} is used to describe groups of sections in
2981 the linked program. @code{@value{LD}} puts all partial programs' text
2982 sections in contiguous addresses in the linked program. It is
2983 customary to refer to the @emph{text section} of a program, meaning all
2984 the addresses of all partial programs' text sections. Likewise for
2985 data and bss sections.
2987 Some sections are manipulated by @code{@value{LD}}; others are invented for
2988 use of @command{@value{AS}} and have no meaning except during assembly.
2991 @section Linker Sections
2992 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2997 @cindex named sections
2998 @cindex sections, named
2999 @item named sections
3002 @cindex text section
3003 @cindex data section
3007 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
3008 separate but equal sections. Anything you can say of one section is
3011 When the program is running, however, it is
3012 customary for the text section to be unalterable. The
3013 text section is often shared among processes: it contains
3014 instructions, constants and the like. The data section of a running
3015 program is usually alterable: for example, C variables would be stored
3016 in the data section.
3021 This section contains zeroed bytes when your program begins running. It
3022 is used to hold uninitialized variables or common storage. The length of
3023 each partial program's bss section is important, but because it starts
3024 out containing zeroed bytes there is no need to store explicit zero
3025 bytes in the object file. The bss section was invented to eliminate
3026 those explicit zeros from object files.
3028 @cindex absolute section
3029 @item absolute section
3030 Address 0 of this section is always ``relocated'' to runtime address 0.
3031 This is useful if you want to refer to an address that @code{@value{LD}} must
3032 not change when relocating. In this sense we speak of absolute
3033 addresses being ``unrelocatable'': they do not change during relocation.
3035 @cindex undefined section
3036 @item undefined section
3037 This ``section'' is a catch-all for address references to objects not in
3038 the preceding sections.
3039 @c FIXME: ref to some other doc on obj-file formats could go here.
3042 @cindex relocation example
3043 An idealized example of three relocatable sections follows.
3045 The example uses the traditional section names @samp{.text} and @samp{.data}.
3047 Memory addresses are on the horizontal axis.
3051 @c END TEXI2ROFF-KILL
3054 partial program # 1: |ttttt|dddd|00|
3061 partial program # 2: |TTT|DDD|000|
3064 +--+---+-----+--+----+---+-----+~~
3065 linked program: | |TTT|ttttt| |dddd|DDD|00000|
3066 +--+---+-----+--+----+---+-----+~~
3068 addresses: 0 @dots{}
3075 \line{\it Partial program \#1: \hfil}
3076 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3077 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
3079 \line{\it Partial program \#2: \hfil}
3080 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3081 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
3083 \line{\it linked program: \hfil}
3084 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
3085 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
3086 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
3087 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
3089 \line{\it addresses: \hfil}
3093 @c END TEXI2ROFF-KILL
3096 @section Assembler Internal Sections
3098 @cindex internal assembler sections
3099 @cindex sections in messages, internal
3100 These sections are meant only for the internal use of @command{@value{AS}}. They
3101 have no meaning at run-time. You do not really need to know about these
3102 sections for most purposes; but they can be mentioned in @command{@value{AS}}
3103 warning messages, so it might be helpful to have an idea of their
3104 meanings to @command{@value{AS}}. These sections are used to permit the
3105 value of every expression in your assembly language program to be a
3106 section-relative address.
3109 @cindex assembler internal logic error
3110 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
3111 An internal assembler logic error has been found. This means there is a
3112 bug in the assembler.
3114 @cindex expr (internal section)
3116 The assembler stores complex expression internally as combinations of
3117 symbols. When it needs to represent an expression as a symbol, it puts
3118 it in the expr section.
3120 @c FIXME item transfer[t] vector preload
3121 @c FIXME item transfer[t] vector postload
3122 @c FIXME item register
3126 @section Sub-Sections
3128 @cindex numbered subsections
3129 @cindex grouping data
3135 fall into two sections: text and data.
3137 You may have separate groups of
3139 data in named sections
3143 data in named sections
3149 that you want to end up near to each other in the object file, even though they
3150 are not contiguous in the assembler source. @command{@value{AS}} allows you to
3151 use @dfn{subsections} for this purpose. Within each section, there can be
3152 numbered subsections with values from 0 to 8192. Objects assembled into the
3153 same subsection go into the object file together with other objects in the same
3154 subsection. For example, a compiler might want to store constants in the text
3155 section, but might not want to have them interspersed with the program being
3156 assembled. In this case, the compiler could issue a @samp{.text 0} before each
3157 section of code being output, and a @samp{.text 1} before each group of
3158 constants being output.
3160 Subsections are optional. If you do not use subsections, everything
3161 goes in subsection number zero.
3164 Each subsection is zero-padded up to a multiple of four bytes.
3165 (Subsections may be padded a different amount on different flavors
3166 of @command{@value{AS}}.)
3170 On the H8/300 platform, each subsection is zero-padded to a word
3171 boundary (two bytes).
3172 The same is true on the Renesas SH.
3175 @c FIXME section padding (alignment)?
3176 @c Rich Pixley says padding here depends on target obj code format; that
3177 @c doesn't seem particularly useful to say without further elaboration,
3178 @c so for now I say nothing about it. If this is a generic BFD issue,
3179 @c these paragraphs might need to vanish from this manual, and be
3180 @c discussed in BFD chapter of binutils (or some such).
3184 Subsections appear in your object file in numeric order, lowest numbered
3185 to highest. (All this to be compatible with other people's assemblers.)
3186 The object file contains no representation of subsections; @code{@value{LD}} and
3187 other programs that manipulate object files see no trace of them.
3188 They just see all your text subsections as a text section, and all your
3189 data subsections as a data section.
3191 To specify which subsection you want subsequent statements assembled
3192 into, use a numeric argument to specify it, in a @samp{.text
3193 @var{expression}} or a @samp{.data @var{expression}} statement.
3196 When generating COFF output, you
3201 can also use an extra subsection
3202 argument with arbitrary named sections: @samp{.section @var{name},
3207 When generating ELF output, you
3212 can also use the @code{.subsection} directive (@pxref{SubSection})
3213 to specify a subsection: @samp{.subsection @var{expression}}.
3215 @var{Expression} should be an absolute expression
3216 (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0}
3217 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3218 begins in @code{text 0}. For instance:
3220 .text 0 # The default subsection is text 0 anyway.
3221 .ascii "This lives in the first text subsection. *"
3223 .ascii "But this lives in the second text subsection."
3225 .ascii "This lives in the data section,"
3226 .ascii "in the first data subsection."
3228 .ascii "This lives in the first text section,"
3229 .ascii "immediately following the asterisk (*)."
3232 Each section has a @dfn{location counter} incremented by one for every byte
3233 assembled into that section. Because subsections are merely a convenience
3234 restricted to @command{@value{AS}} there is no concept of a subsection location
3235 counter. There is no way to directly manipulate a location counter---but the
3236 @code{.align} directive changes it, and any label definition captures its
3237 current value. The location counter of the section where statements are being
3238 assembled is said to be the @dfn{active} location counter.
3241 @section bss Section
3244 @cindex common variable storage
3245 The bss section is used for local common variable storage.
3246 You may allocate address space in the bss section, but you may
3247 not dictate data to load into it before your program executes. When
3248 your program starts running, all the contents of the bss
3249 section are zeroed bytes.
3251 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3252 @ref{Lcomm,,@code{.lcomm}}.
3254 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3255 another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}.
3258 When assembling for a target which supports multiple sections, such as ELF or
3259 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3260 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3261 section. Typically the section will only contain symbol definitions and
3262 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3269 Symbols are a central concept: the programmer uses symbols to name
3270 things, the linker uses symbols to link, and the debugger uses symbols
3274 @cindex debuggers, and symbol order
3275 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3276 the same order they were declared. This may break some debuggers.
3281 * Setting Symbols:: Giving Symbols Other Values
3282 * Symbol Names:: Symbol Names
3283 * Dot:: The Special Dot Symbol
3284 * Symbol Attributes:: Symbol Attributes
3291 A @dfn{label} is written as a symbol immediately followed by a colon
3292 @samp{:}. The symbol then represents the current value of the
3293 active location counter, and is, for example, a suitable instruction
3294 operand. You are warned if you use the same symbol to represent two
3295 different locations: the first definition overrides any other
3299 On the HPPA, the usual form for a label need not be immediately followed by a
3300 colon, but instead must start in column zero. Only one label may be defined on
3301 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3302 provides a special directive @code{.label} for defining labels more flexibly.
3305 @node Setting Symbols
3306 @section Giving Symbols Other Values
3308 @cindex assigning values to symbols
3309 @cindex symbol values, assigning
3310 A symbol can be given an arbitrary value by writing a symbol, followed
3311 by an equals sign @samp{=}, followed by an expression
3312 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3313 directive. @xref{Set,,@code{.set}}. In the same way, using a double
3314 equals sign @samp{=}@samp{=} here represents an equivalent of the
3315 @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}.
3318 Blackfin does not support symbol assignment with @samp{=}.
3322 @section Symbol Names
3324 @cindex symbol names
3325 @cindex names, symbol
3326 @ifclear SPECIAL-SYMS
3327 Symbol names begin with a letter or with one of @samp{._}. On most
3328 machines, you can also use @code{$} in symbol names; exceptions are
3329 noted in @ref{Machine Dependencies}. That character may be followed by any
3330 string of digits, letters, dollar signs (unless otherwise noted for a
3331 particular target machine), and underscores.
3335 Symbol names begin with a letter or with one of @samp{._}. On the
3336 Renesas SH you can also use @code{$} in symbol names. That
3337 character may be followed by any string of digits, letters, dollar signs (save
3338 on the H8/300), and underscores.
3342 Case of letters is significant: @code{foo} is a different symbol name
3345 Each symbol has exactly one name. Each name in an assembly language program
3346 refers to exactly one symbol. You may use that symbol name any number of times
3349 @subheading Local Symbol Names
3351 @cindex local symbol names
3352 @cindex symbol names, local
3353 A local symbol is any symbol beginning with certain local label prefixes.
3354 By default, the local label prefix is @samp{.L} for ELF systems or
3355 @samp{L} for traditional a.out systems, but each target may have its own
3356 set of local label prefixes.
3358 On the HPPA local symbols begin with @samp{L$}.
3361 Local symbols are defined and used within the assembler, but they are
3362 normally not saved in object files. Thus, they are not visible when debugging.
3363 You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols:
3364 @option{-L}}) to retain the local symbols in the object files.
3366 @subheading Local Labels
3368 @cindex local labels
3369 @cindex temporary symbol names
3370 @cindex symbol names, temporary
3371 Local labels help compilers and programmers use names temporarily.
3372 They create symbols which are guaranteed to be unique over the entire scope of
3373 the input source code and which can be referred to by a simple notation.
3374 To define a local label, write a label of the form @samp{@b{N}:} (where @b{N}
3375 represents any positive integer). To refer to the most recent previous
3376 definition of that label write @samp{@b{N}b}, using the same number as when
3377 you defined the label. To refer to the next definition of a local label, write
3378 @samp{@b{N}f}---the @samp{b} stands for ``backwards'' and the @samp{f} stands
3381 There is no restriction on how you can use these labels, and you can reuse them
3382 too. So that it is possible to repeatedly define the same local label (using
3383 the same number @samp{@b{N}}), although you can only refer to the most recently
3384 defined local label of that number (for a backwards reference) or the next
3385 definition of a specific local label for a forward reference. It is also worth
3386 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3387 implemented in a slightly more efficient manner than the others.
3398 Which is the equivalent of:
3401 label_1: branch label_3
3402 label_2: branch label_1
3403 label_3: branch label_4
3404 label_4: branch label_3
3407 Local label names are only a notational device. They are immediately
3408 transformed into more conventional symbol names before the assembler uses them.
3409 The symbol names are stored in the symbol table, appear in error messages, and
3410 are optionally emitted to the object file. The names are constructed using
3414 @item @emph{local label prefix}
3415 All local symbols begin with the system-specific local label prefix.
3416 Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols
3417 that start with the local label prefix. These labels are
3418 used for symbols you are never intended to see. If you use the
3419 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3420 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3421 you may use them in debugging.
3424 This is the number that was used in the local label definition. So if the
3425 label is written @samp{55:} then the number is @samp{55}.
3428 This unusual character is included so you do not accidentally invent a symbol
3429 of the same name. The character has ASCII value of @samp{\002} (control-B).
3431 @item @emph{ordinal number}
3432 This is a serial number to keep the labels distinct. The first definition of
3433 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3434 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3435 the number @samp{1} and its 15th definition gets @samp{15} as well.
3438 So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and
3439 the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}.
3441 @subheading Dollar Local Labels
3442 @cindex dollar local symbols
3444 @code{@value{AS}} also supports an even more local form of local labels called
3445 dollar labels. These labels go out of scope (i.e., they become undefined) as
3446 soon as a non-local label is defined. Thus they remain valid for only a small
3447 region of the input source code. Normal local labels, by contrast, remain in
3448 scope for the entire file, or until they are redefined by another occurrence of
3449 the same local label.
3451 Dollar labels are defined in exactly the same way as ordinary local labels,
3452 except that they have a dollar sign suffix to their numeric value, e.g.,
3455 They can also be distinguished from ordinary local labels by their transformed
3456 names which use ASCII character @samp{\001} (control-A) as the magic character
3457 to distinguish them from ordinary labels. For example, the fifth definition of
3458 @samp{6$} may be named @samp{.L6@kbd{C-A}5}.
3461 @section The Special Dot Symbol
3463 @cindex dot (symbol)
3464 @cindex @code{.} (symbol)
3465 @cindex current address
3466 @cindex location counter
3467 The special symbol @samp{.} refers to the current address that
3468 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3469 .long .} defines @code{melvin} to contain its own address.
3470 Assigning a value to @code{.} is treated the same as a @code{.org}
3472 @ifclear no-space-dir
3473 Thus, the expression @samp{.=.+4} is the same as saying
3477 @node Symbol Attributes
3478 @section Symbol Attributes
3480 @cindex symbol attributes
3481 @cindex attributes, symbol
3482 Every symbol has, as well as its name, the attributes ``Value'' and
3483 ``Type''. Depending on output format, symbols can also have auxiliary
3486 The detailed definitions are in @file{a.out.h}.
3489 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3490 all these attributes, and probably won't warn you. This makes the
3491 symbol an externally defined symbol, which is generally what you
3495 * Symbol Value:: Value
3496 * Symbol Type:: Type
3499 * a.out Symbols:: Symbol Attributes: @code{a.out}
3503 * a.out Symbols:: Symbol Attributes: @code{a.out}
3506 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3511 * COFF Symbols:: Symbol Attributes for COFF
3514 * SOM Symbols:: Symbol Attributes for SOM
3521 @cindex value of a symbol
3522 @cindex symbol value
3523 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3524 location in the text, data, bss or absolute sections the value is the
3525 number of addresses from the start of that section to the label.
3526 Naturally for text, data and bss sections the value of a symbol changes
3527 as @code{@value{LD}} changes section base addresses during linking. Absolute
3528 symbols' values do not change during linking: that is why they are
3531 The value of an undefined symbol is treated in a special way. If it is
3532 0 then the symbol is not defined in this assembler source file, and
3533 @code{@value{LD}} tries to determine its value from other files linked into the
3534 same program. You make this kind of symbol simply by mentioning a symbol
3535 name without defining it. A non-zero value represents a @code{.comm}
3536 common declaration. The value is how much common storage to reserve, in
3537 bytes (addresses). The symbol refers to the first address of the
3543 @cindex type of a symbol
3545 The type attribute of a symbol contains relocation (section)
3546 information, any flag settings indicating that a symbol is external, and
3547 (optionally), other information for linkers and debuggers. The exact
3548 format depends on the object-code output format in use.
3553 @c The following avoids a "widow" subsection title. @group would be
3554 @c better if it were available outside examples.
3557 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3559 @cindex @code{b.out} symbol attributes
3560 @cindex symbol attributes, @code{b.out}
3561 These symbol attributes appear only when @command{@value{AS}} is configured for
3562 one of the Berkeley-descended object output formats---@code{a.out} or
3568 @subsection Symbol Attributes: @code{a.out}
3570 @cindex @code{a.out} symbol attributes
3571 @cindex symbol attributes, @code{a.out}
3577 @subsection Symbol Attributes: @code{a.out}
3579 @cindex @code{a.out} symbol attributes
3580 @cindex symbol attributes, @code{a.out}
3584 * Symbol Desc:: Descriptor
3585 * Symbol Other:: Other
3589 @subsubsection Descriptor
3591 @cindex descriptor, of @code{a.out} symbol
3592 This is an arbitrary 16-bit value. You may establish a symbol's
3593 descriptor value by using a @code{.desc} statement
3594 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3595 @command{@value{AS}}.
3598 @subsubsection Other
3600 @cindex other attribute, of @code{a.out} symbol
3601 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3606 @subsection Symbol Attributes for COFF
3608 @cindex COFF symbol attributes
3609 @cindex symbol attributes, COFF
3611 The COFF format supports a multitude of auxiliary symbol attributes;
3612 like the primary symbol attributes, they are set between @code{.def} and
3613 @code{.endef} directives.
3615 @subsubsection Primary Attributes
3617 @cindex primary attributes, COFF symbols
3618 The symbol name is set with @code{.def}; the value and type,
3619 respectively, with @code{.val} and @code{.type}.
3621 @subsubsection Auxiliary Attributes
3623 @cindex auxiliary attributes, COFF symbols
3624 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3625 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3626 table information for COFF.
3631 @subsection Symbol Attributes for SOM
3633 @cindex SOM symbol attributes
3634 @cindex symbol attributes, SOM
3636 The SOM format for the HPPA supports a multitude of symbol attributes set with
3637 the @code{.EXPORT} and @code{.IMPORT} directives.
3639 The attributes are described in @cite{HP9000 Series 800 Assembly
3640 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3641 @code{EXPORT} assembler directive documentation.
3645 @chapter Expressions
3649 @cindex numeric values
3650 An @dfn{expression} specifies an address or numeric value.
3651 Whitespace may precede and/or follow an expression.
3653 The result of an expression must be an absolute number, or else an offset into
3654 a particular section. If an expression is not absolute, and there is not
3655 enough information when @command{@value{AS}} sees the expression to know its
3656 section, a second pass over the source program might be necessary to interpret
3657 the expression---but the second pass is currently not implemented.
3658 @command{@value{AS}} aborts with an error message in this situation.
3661 * Empty Exprs:: Empty Expressions
3662 * Integer Exprs:: Integer Expressions
3666 @section Empty Expressions
3668 @cindex empty expressions
3669 @cindex expressions, empty
3670 An empty expression has no value: it is just whitespace or null.
3671 Wherever an absolute expression is required, you may omit the
3672 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3673 is compatible with other assemblers.
3676 @section Integer Expressions
3678 @cindex integer expressions
3679 @cindex expressions, integer
3680 An @dfn{integer expression} is one or more @emph{arguments} delimited
3681 by @emph{operators}.
3684 * Arguments:: Arguments
3685 * Operators:: Operators
3686 * Prefix Ops:: Prefix Operators
3687 * Infix Ops:: Infix Operators
3691 @subsection Arguments
3693 @cindex expression arguments
3694 @cindex arguments in expressions
3695 @cindex operands in expressions
3696 @cindex arithmetic operands
3697 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3698 contexts arguments are sometimes called ``arithmetic operands''. In
3699 this manual, to avoid confusing them with the ``instruction operands'' of
3700 the machine language, we use the term ``argument'' to refer to parts of
3701 expressions only, reserving the word ``operand'' to refer only to machine
3702 instruction operands.
3704 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3705 @var{section} is one of text, data, bss, absolute,
3706 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3709 Numbers are usually integers.
3711 A number can be a flonum or bignum. In this case, you are warned
3712 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3713 these 32 bits are an integer. You may write integer-manipulating
3714 instructions that act on exotic constants, compatible with other
3717 @cindex subexpressions
3718 Subexpressions are a left parenthesis @samp{(} followed by an integer
3719 expression, followed by a right parenthesis @samp{)}; or a prefix
3720 operator followed by an argument.
3723 @subsection Operators
3725 @cindex operators, in expressions
3726 @cindex arithmetic functions
3727 @cindex functions, in expressions
3728 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3729 operators are followed by an argument. Infix operators appear
3730 between their arguments. Operators may be preceded and/or followed by
3734 @subsection Prefix Operator
3736 @cindex prefix operators
3737 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3738 one argument, which must be absolute.
3740 @c the tex/end tex stuff surrounding this small table is meant to make
3741 @c it align, on the printed page, with the similar table in the next
3742 @c section (which is inside an enumerate).
3744 \global\advance\leftskip by \itemindent
3749 @dfn{Negation}. Two's complement negation.
3751 @dfn{Complementation}. Bitwise not.
3755 \global\advance\leftskip by -\itemindent
3759 @subsection Infix Operators
3761 @cindex infix operators
3762 @cindex operators, permitted arguments
3763 @dfn{Infix operators} take two arguments, one on either side. Operators
3764 have precedence, but operations with equal precedence are performed left
3765 to right. Apart from @code{+} or @option{-}, both arguments must be
3766 absolute, and the result is absolute.
3769 @cindex operator precedence
3770 @cindex precedence of operators
3777 @dfn{Multiplication}.
3780 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3786 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3789 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3793 Intermediate precedence
3798 @dfn{Bitwise Inclusive Or}.
3804 @dfn{Bitwise Exclusive Or}.
3807 @dfn{Bitwise Or Not}.
3814 @cindex addition, permitted arguments
3815 @cindex plus, permitted arguments
3816 @cindex arguments for addition
3818 @dfn{Addition}. If either argument is absolute, the result has the section of
3819 the other argument. You may not add together arguments from different
3822 @cindex subtraction, permitted arguments
3823 @cindex minus, permitted arguments
3824 @cindex arguments for subtraction
3826 @dfn{Subtraction}. If the right argument is absolute, the
3827 result has the section of the left argument.
3828 If both arguments are in the same section, the result is absolute.
3829 You may not subtract arguments from different sections.
3830 @c FIXME is there still something useful to say about undefined - undefined ?
3832 @cindex comparison expressions
3833 @cindex expressions, comparison
3838 @dfn{Is Not Equal To}
3842 @dfn{Is Greater Than}
3844 @dfn{Is Greater Than Or Equal To}
3846 @dfn{Is Less Than Or Equal To}
3848 The comparison operators can be used as infix operators. A true results has a
3849 value of -1 whereas a false result has a value of 0. Note, these operators
3850 perform signed comparisons.
3853 @item Lowest Precedence
3862 These two logical operations can be used to combine the results of sub
3863 expressions. Note, unlike the comparison operators a true result returns a
3864 value of 1 but a false results does still return 0. Also note that the logical
3865 or operator has a slightly lower precedence than logical and.
3870 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3871 address; you can only have a defined section in one of the two arguments.
3874 @chapter Assembler Directives
3876 @cindex directives, machine independent
3877 @cindex pseudo-ops, machine independent
3878 @cindex machine independent directives
3879 All assembler directives have names that begin with a period (@samp{.}).
3880 The rest of the name is letters, usually in lower case.
3882 This chapter discusses directives that are available regardless of the
3883 target machine configuration for the @sc{gnu} assembler.
3885 Some machine configurations provide additional directives.
3886 @xref{Machine Dependencies}.
3889 @ifset machine-directives
3890 @xref{Machine Dependencies}, for additional directives.
3895 * Abort:: @code{.abort}
3897 * ABORT (COFF):: @code{.ABORT}
3900 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3901 * Altmacro:: @code{.altmacro}
3902 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3903 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3904 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3905 * Byte:: @code{.byte @var{expressions}}
3906 * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
3907 * Comm:: @code{.comm @var{symbol} , @var{length} }
3908 * Data:: @code{.data @var{subsection}}
3910 * Def:: @code{.def @var{name}}
3913 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3919 * Double:: @code{.double @var{flonums}}
3920 * Eject:: @code{.eject}
3921 * Else:: @code{.else}
3922 * Elseif:: @code{.elseif}
3925 * Endef:: @code{.endef}
3928 * Endfunc:: @code{.endfunc}
3929 * Endif:: @code{.endif}
3930 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3931 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3932 * Eqv:: @code{.eqv @var{symbol}, @var{expression}}
3934 * Error:: @code{.error @var{string}}
3935 * Exitm:: @code{.exitm}
3936 * Extern:: @code{.extern}
3937 * Fail:: @code{.fail}
3938 * File:: @code{.file}
3939 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3940 * Float:: @code{.float @var{flonums}}
3941 * Func:: @code{.func}
3942 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3944 * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
3945 * Hidden:: @code{.hidden @var{names}}
3948 * hword:: @code{.hword @var{expressions}}
3949 * Ident:: @code{.ident}
3950 * If:: @code{.if @var{absolute expression}}
3951 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3952 * Include:: @code{.include "@var{file}"}
3953 * Int:: @code{.int @var{expressions}}
3955 * Internal:: @code{.internal @var{names}}
3958 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3959 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3960 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3961 * Lflags:: @code{.lflags}
3962 @ifclear no-line-dir
3963 * Line:: @code{.line @var{line-number}}
3966 * Linkonce:: @code{.linkonce [@var{type}]}
3967 * List:: @code{.list}
3968 * Ln:: @code{.ln @var{line-number}}
3969 * Loc:: @code{.loc @var{fileno} @var{lineno}}
3970 * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}}
3972 * Local:: @code{.local @var{names}}
3975 * Long:: @code{.long @var{expressions}}
3977 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3980 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3981 * MRI:: @code{.mri @var{val}}
3982 * Noaltmacro:: @code{.noaltmacro}
3983 * Nolist:: @code{.nolist}
3984 * Octa:: @code{.octa @var{bignums}}
3985 * Org:: @code{.org @var{new-lc}, @var{fill}}
3986 * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3988 * PopSection:: @code{.popsection}
3989 * Previous:: @code{.previous}
3992 * Print:: @code{.print @var{string}}
3994 * Protected:: @code{.protected @var{names}}
3997 * Psize:: @code{.psize @var{lines}, @var{columns}}
3998 * Purgem:: @code{.purgem @var{name}}
4000 * PushSection:: @code{.pushsection @var{name}}
4003 * Quad:: @code{.quad @var{bignums}}
4004 * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
4005 * Rept:: @code{.rept @var{count}}
4006 * Sbttl:: @code{.sbttl "@var{subheading}"}
4008 * Scl:: @code{.scl @var{class}}
4011 * Section:: @code{.section @var{name}[, @var{flags}]}
4014 * Set:: @code{.set @var{symbol}, @var{expression}}
4015 * Short:: @code{.short @var{expressions}}
4016 * Single:: @code{.single @var{flonums}}
4018 * Size:: @code{.size [@var{name} , @var{expression}]}
4020 @ifclear no-space-dir
4021 * Skip:: @code{.skip @var{size} , @var{fill}}
4024 * Sleb128:: @code{.sleb128 @var{expressions}}
4025 @ifclear no-space-dir
4026 * Space:: @code{.space @var{size} , @var{fill}}
4029 * Stab:: @code{.stabd, .stabn, .stabs}
4032 * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
4033 * Struct:: @code{.struct @var{expression}}
4035 * SubSection:: @code{.subsection}
4036 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
4040 * Tag:: @code{.tag @var{structname}}
4043 * Text:: @code{.text @var{subsection}}
4044 * Title:: @code{.title "@var{heading}"}
4046 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
4049 * Uleb128:: @code{.uleb128 @var{expressions}}
4051 * Val:: @code{.val @var{addr}}
4055 * Version:: @code{.version "@var{string}"}
4056 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
4057 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
4060 * Warning:: @code{.warning @var{string}}
4061 * Weak:: @code{.weak @var{names}}
4062 * Weakref:: @code{.weakref @var{alias}, @var{symbol}}
4063 * Word:: @code{.word @var{expressions}}
4064 * Deprecated:: Deprecated Directives
4068 @section @code{.abort}
4070 @cindex @code{abort} directive
4071 @cindex stopping the assembly
4072 This directive stops the assembly immediately. It is for
4073 compatibility with other assemblers. The original idea was that the
4074 assembly language source would be piped into the assembler. If the sender
4075 of the source quit, it could use this directive tells @command{@value{AS}} to
4076 quit also. One day @code{.abort} will not be supported.
4080 @section @code{.ABORT} (COFF)
4082 @cindex @code{ABORT} directive
4083 When producing COFF output, @command{@value{AS}} accepts this directive as a
4084 synonym for @samp{.abort}.
4087 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
4093 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4095 @cindex padding the location counter
4096 @cindex @code{align} directive
4097 Pad the location counter (in the current subsection) to a particular storage
4098 boundary. The first expression (which must be absolute) is the alignment
4099 required, as described below.
4101 The second expression (also absolute) gives the fill value to be stored in the
4102 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4103 padding bytes are normally zero. However, on some systems, if the section is
4104 marked as containing code and the fill value is omitted, the space is filled
4105 with no-op instructions.
4107 The third expression is also absolute, and is also optional. If it is present,
4108 it is the maximum number of bytes that should be skipped by this alignment
4109 directive. If doing the alignment would require skipping more bytes than the
4110 specified maximum, then the alignment is not done at all. You can omit the
4111 fill value (the second argument) entirely by simply using two commas after the
4112 required alignment; this can be useful if you want the alignment to be filled
4113 with no-op instructions when appropriate.
4115 The way the required alignment is specified varies from system to system.
4116 For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32,
4117 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
4118 alignment request in bytes. For example @samp{.align 8} advances
4119 the location counter until it is a multiple of 8. If the location counter
4120 is already a multiple of 8, no change is needed. For the tic54x, the
4121 first expression is the alignment request in words.
4123 For other systems, including ppc, i386 using a.out format, arm and
4124 strongarm, it is the
4125 number of low-order zero bits the location counter must have after
4126 advancement. For example @samp{.align 3} advances the location
4127 counter until it a multiple of 8. If the location counter is already a
4128 multiple of 8, no change is needed.
4130 This inconsistency is due to the different behaviors of the various
4131 native assemblers for these systems which GAS must emulate.
4132 GAS also provides @code{.balign} and @code{.p2align} directives,
4133 described later, which have a consistent behavior across all
4134 architectures (but are specific to GAS).
4137 @section @code{.altmacro}
4138 Enable alternate macro mode, enabling:
4141 @item LOCAL @var{name} [ , @dots{} ]
4142 One additional directive, @code{LOCAL}, is available. It is used to
4143 generate a string replacement for each of the @var{name} arguments, and
4144 replace any instances of @var{name} in each macro expansion. The
4145 replacement string is unique in the assembly, and different for each
4146 separate macro expansion. @code{LOCAL} allows you to write macros that
4147 define symbols, without fear of conflict between separate macro expansions.
4149 @item String delimiters
4150 You can write strings delimited in these other ways besides
4151 @code{"@var{string}"}:
4154 @item '@var{string}'
4155 You can delimit strings with single-quote characters.
4157 @item <@var{string}>
4158 You can delimit strings with matching angle brackets.
4161 @item single-character string escape
4162 To include any single character literally in a string (even if the
4163 character would otherwise have some special meaning), you can prefix the
4164 character with @samp{!} (an exclamation mark). For example, you can
4165 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4167 @item Expression results as strings
4168 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4169 and use the result as a string.
4173 @section @code{.ascii "@var{string}"}@dots{}
4175 @cindex @code{ascii} directive
4176 @cindex string literals
4177 @code{.ascii} expects zero or more string literals (@pxref{Strings})
4178 separated by commas. It assembles each string (with no automatic
4179 trailing zero byte) into consecutive addresses.
4182 @section @code{.asciz "@var{string}"}@dots{}
4184 @cindex @code{asciz} directive
4185 @cindex zero-terminated strings
4186 @cindex null-terminated strings
4187 @code{.asciz} is just like @code{.ascii}, but each string is followed by
4188 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
4191 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4193 @cindex padding the location counter given number of bytes
4194 @cindex @code{balign} directive
4195 Pad the location counter (in the current subsection) to a particular
4196 storage boundary. The first expression (which must be absolute) is the
4197 alignment request in bytes. For example @samp{.balign 8} advances
4198 the location counter until it is a multiple of 8. If the location counter
4199 is already a multiple of 8, no change is needed.
4201 The second expression (also absolute) gives the fill value to be stored in the
4202 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4203 padding bytes are normally zero. However, on some systems, if the section is
4204 marked as containing code and the fill value is omitted, the space is filled
4205 with no-op instructions.
4207 The third expression is also absolute, and is also optional. If it is present,
4208 it is the maximum number of bytes that should be skipped by this alignment
4209 directive. If doing the alignment would require skipping more bytes than the
4210 specified maximum, then the alignment is not done at all. You can omit the
4211 fill value (the second argument) entirely by simply using two commas after the
4212 required alignment; this can be useful if you want the alignment to be filled
4213 with no-op instructions when appropriate.
4215 @cindex @code{balignw} directive
4216 @cindex @code{balignl} directive
4217 The @code{.balignw} and @code{.balignl} directives are variants of the
4218 @code{.balign} directive. The @code{.balignw} directive treats the fill
4219 pattern as a two byte word value. The @code{.balignl} directives treats the
4220 fill pattern as a four byte longword value. For example, @code{.balignw
4221 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4222 filled in with the value 0x368d (the exact placement of the bytes depends upon
4223 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4227 @section @code{.byte @var{expressions}}
4229 @cindex @code{byte} directive
4230 @cindex integers, one byte
4231 @code{.byte} expects zero or more expressions, separated by commas.
4232 Each expression is assembled into the next byte.
4234 @node CFI directives
4235 @section @code{.cfi_sections @var{section_list}}
4236 @cindex @code{cfi_sections} directive
4237 @code{.cfi_sections} may be used to specify whether CFI directives
4238 should emit @code{.eh_frame} section and/or @code{.debug_frame} section.
4239 If @var{section_list} is @code{.eh_frame}, @code{.eh_frame} is emitted,
4240 if @var{section_list} is @code{.debug_frame}, @code{.debug_frame} is emitted.
4241 To emit both use @code{.eh_frame, .debug_frame}. The default if this
4242 directive is not used is @code{.cfi_sections .eh_frame}.
4244 @section @code{.cfi_startproc [simple]}
4245 @cindex @code{cfi_startproc} directive
4246 @code{.cfi_startproc} is used at the beginning of each function that
4247 should have an entry in @code{.eh_frame}. It initializes some internal
4248 data structures. Don't forget to close the function by
4249 @code{.cfi_endproc}.
4251 Unless @code{.cfi_startproc} is used along with parameter @code{simple}
4252 it also emits some architecture dependent initial CFI instructions.
4254 @section @code{.cfi_endproc}
4255 @cindex @code{cfi_endproc} directive
4256 @code{.cfi_endproc} is used at the end of a function where it closes its
4257 unwind entry previously opened by
4258 @code{.cfi_startproc}, and emits it to @code{.eh_frame}.
4260 @section @code{.cfi_personality @var{encoding} [, @var{exp}]}
4261 @code{.cfi_personality} defines personality routine and its encoding.
4262 @var{encoding} must be a constant determining how the personality
4263 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4264 argument is not present, otherwise second argument should be
4265 a constant or a symbol name. When using indirect encodings,
4266 the symbol provided should be the location where personality
4267 can be loaded from, not the personality routine itself.
4268 The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff},
4269 no personality routine.
4271 @section @code{.cfi_lsda @var{encoding} [, @var{exp}]}
4272 @code{.cfi_lsda} defines LSDA and its encoding.
4273 @var{encoding} must be a constant determining how the LSDA
4274 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4275 argument is not present, otherwise second argument should be a constant
4276 or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff},
4279 @section @code{.cfi_def_cfa @var{register}, @var{offset}}
4280 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4281 address from @var{register} and add @var{offset} to it}.
4283 @section @code{.cfi_def_cfa_register @var{register}}
4284 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4285 now on @var{register} will be used instead of the old one. Offset
4288 @section @code{.cfi_def_cfa_offset @var{offset}}
4289 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4290 remains the same, but @var{offset} is new. Note that it is the
4291 absolute offset that will be added to a defined register to compute
4294 @section @code{.cfi_adjust_cfa_offset @var{offset}}
4295 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4296 value that is added/substracted from the previous offset.
4298 @section @code{.cfi_offset @var{register}, @var{offset}}
4299 Previous value of @var{register} is saved at offset @var{offset} from
4302 @section @code{.cfi_rel_offset @var{register}, @var{offset}}
4303 Previous value of @var{register} is saved at offset @var{offset} from
4304 the current CFA register. This is transformed to @code{.cfi_offset}
4305 using the known displacement of the CFA register from the CFA.
4306 This is often easier to use, because the number will match the
4307 code it's annotating.
4309 @section @code{.cfi_register @var{register1}, @var{register2}}
4310 Previous value of @var{register1} is saved in register @var{register2}.
4312 @section @code{.cfi_restore @var{register}}
4313 @code{.cfi_restore} says that the rule for @var{register} is now the
4314 same as it was at the beginning of the function, after all initial
4315 instruction added by @code{.cfi_startproc} were executed.
4317 @section @code{.cfi_undefined @var{register}}
4318 From now on the previous value of @var{register} can't be restored anymore.
4320 @section @code{.cfi_same_value @var{register}}
4321 Current value of @var{register} is the same like in the previous frame,
4322 i.e. no restoration needed.
4324 @section @code{.cfi_remember_state},
4325 First save all current rules for all registers by @code{.cfi_remember_state},
4326 then totally screw them up by subsequent @code{.cfi_*} directives and when
4327 everything is hopelessly bad, use @code{.cfi_restore_state} to restore
4328 the previous saved state.
4330 @section @code{.cfi_return_column @var{register}}
4331 Change return column @var{register}, i.e. the return address is either
4332 directly in @var{register} or can be accessed by rules for @var{register}.
4334 @section @code{.cfi_signal_frame}
4335 Mark current function as signal trampoline.
4337 @section @code{.cfi_window_save}
4338 SPARC register window has been saved.
4340 @section @code{.cfi_escape} @var{expression}[, @dots{}]
4341 Allows the user to add arbitrary bytes to the unwind info. One
4342 might use this to add OS-specific CFI opcodes, or generic CFI
4343 opcodes that GAS does not yet support.
4345 @section @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}}
4346 The current value of @var{register} is @var{label}. The value of @var{label}
4347 will be encoded in the output file according to @var{encoding}; see the
4348 description of @code{.cfi_personality} for details on this encoding.
4350 The usefulness of equating a register to a fixed label is probably
4351 limited to the return address register. Here, it can be useful to
4352 mark a code segment that has only one return address which is reached
4353 by a direct branch and no copy of the return address exists in memory
4354 or another register.
4357 @section @code{.comm @var{symbol} , @var{length} }
4359 @cindex @code{comm} directive
4360 @cindex symbol, common
4361 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
4362 common symbol in one object file may be merged with a defined or common symbol
4363 of the same name in another object file. If @code{@value{LD}} does not see a
4364 definition for the symbol--just one or more common symbols--then it will
4365 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
4366 absolute expression. If @code{@value{LD}} sees multiple common symbols with
4367 the same name, and they do not all have the same size, it will allocate space
4368 using the largest size.
4371 When using ELF or (as a GNU extension) PE, the @code{.comm} directive takes
4372 an optional third argument. This is the desired alignment of the symbol,
4373 specified for ELF as a byte boundary (for example, an alignment of 16 means
4374 that the least significant 4 bits of the address should be zero), and for PE
4375 as a power of two (for example, an alignment of 5 means aligned to a 32-byte
4376 boundary). The alignment must be an absolute expression, and it must be a
4377 power of two. If @code{@value{LD}} allocates uninitialized memory for the
4378 common symbol, it will use the alignment when placing the symbol. If no
4379 alignment is specified, @command{@value{AS}} will set the alignment to the
4380 largest power of two less than or equal to the size of the symbol, up to a
4381 maximum of 16 on ELF, or the default section alignment of 4 on PE@footnote{This
4382 is not the same as the executable image file alignment controlled by @code{@value{LD}}'s
4383 @samp{--section-alignment} option; image file sections in PE are aligned to
4384 multiples of 4096, which is far too large an alignment for ordinary variables.
4385 It is rather the default alignment for (non-debug) sections within object
4386 (@samp{*.o}) files, which are less strictly aligned.}.
4390 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4391 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4395 @section @code{.data @var{subsection}}
4397 @cindex @code{data} directive
4398 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4399 end of the data subsection numbered @var{subsection} (which is an
4400 absolute expression). If @var{subsection} is omitted, it defaults
4405 @section @code{.def @var{name}}
4407 @cindex @code{def} directive
4408 @cindex COFF symbols, debugging
4409 @cindex debugging COFF symbols
4410 Begin defining debugging information for a symbol @var{name}; the
4411 definition extends until the @code{.endef} directive is encountered.
4414 This directive is only observed when @command{@value{AS}} is configured for COFF
4415 format output; when producing @code{b.out}, @samp{.def} is recognized,
4422 @section @code{.desc @var{symbol}, @var{abs-expression}}
4424 @cindex @code{desc} directive
4425 @cindex COFF symbol descriptor
4426 @cindex symbol descriptor, COFF
4427 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4428 to the low 16 bits of an absolute expression.
4431 The @samp{.desc} directive is not available when @command{@value{AS}} is
4432 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4433 object format. For the sake of compatibility, @command{@value{AS}} accepts
4434 it, but produces no output, when configured for COFF.
4440 @section @code{.dim}
4442 @cindex @code{dim} directive
4443 @cindex COFF auxiliary symbol information
4444 @cindex auxiliary symbol information, COFF
4445 This directive is generated by compilers to include auxiliary debugging
4446 information in the symbol table. It is only permitted inside
4447 @code{.def}/@code{.endef} pairs.
4450 @samp{.dim} is only meaningful when generating COFF format output; when
4451 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4457 @section @code{.double @var{flonums}}
4459 @cindex @code{double} directive
4460 @cindex floating point numbers (double)
4461 @code{.double} expects zero or more flonums, separated by commas. It
4462 assembles floating point numbers.
4464 The exact kind of floating point numbers emitted depends on how
4465 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4469 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4470 in @sc{ieee} format.
4475 @section @code{.eject}
4477 @cindex @code{eject} directive
4478 @cindex new page, in listings
4479 @cindex page, in listings
4480 @cindex listing control: new page
4481 Force a page break at this point, when generating assembly listings.
4484 @section @code{.else}
4486 @cindex @code{else} directive
4487 @code{.else} is part of the @command{@value{AS}} support for conditional
4488 assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section
4489 of code to be assembled if the condition for the preceding @code{.if}
4493 @section @code{.elseif}
4495 @cindex @code{elseif} directive
4496 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4497 assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new
4498 @code{.if} block that would otherwise fill the entire @code{.else} section.
4501 @section @code{.end}
4503 @cindex @code{end} directive
4504 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4505 process anything in the file past the @code{.end} directive.
4509 @section @code{.endef}
4511 @cindex @code{endef} directive
4512 This directive flags the end of a symbol definition begun with
4516 @samp{.endef} is only meaningful when generating COFF format output; if
4517 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4518 directive but ignores it.
4523 @section @code{.endfunc}
4524 @cindex @code{endfunc} directive
4525 @code{.endfunc} marks the end of a function specified with @code{.func}.
4528 @section @code{.endif}
4530 @cindex @code{endif} directive
4531 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4532 it marks the end of a block of code that is only assembled
4533 conditionally. @xref{If,,@code{.if}}.
4536 @section @code{.equ @var{symbol}, @var{expression}}
4538 @cindex @code{equ} directive
4539 @cindex assigning values to symbols
4540 @cindex symbols, assigning values to
4541 This directive sets the value of @var{symbol} to @var{expression}.
4542 It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}.
4545 The syntax for @code{equ} on the HPPA is
4546 @samp{@var{symbol} .equ @var{expression}}.
4550 The syntax for @code{equ} on the Z80 is
4551 @samp{@var{symbol} equ @var{expression}}.
4552 On the Z80 it is an eror if @var{symbol} is already defined,
4553 but the symbol is not protected from later redefinition.
4554 Compare @ref{Equiv}.
4558 @section @code{.equiv @var{symbol}, @var{expression}}
4559 @cindex @code{equiv} directive
4560 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4561 the assembler will signal an error if @var{symbol} is already defined. Note a
4562 symbol which has been referenced but not actually defined is considered to be
4565 Except for the contents of the error message, this is roughly equivalent to
4572 plus it protects the symbol from later redefinition.
4575 @section @code{.eqv @var{symbol}, @var{expression}}
4576 @cindex @code{eqv} directive
4577 The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to
4578 evaluate the expression or any part of it immediately. Instead each time
4579 the resulting symbol is used in an expression, a snapshot of its current
4583 @section @code{.err}
4584 @cindex @code{err} directive
4585 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4586 message and, unless the @option{-Z} option was used, it will not generate an
4587 object file. This can be used to signal an error in conditionally compiled code.
4590 @section @code{.error "@var{string}"}
4591 @cindex error directive
4593 Similarly to @code{.err}, this directive emits an error, but you can specify a
4594 string that will be emitted as the error message. If you don't specify the
4595 message, it defaults to @code{".error directive invoked in source file"}.
4596 @xref{Errors, ,Error and Warning Messages}.
4599 .error "This code has not been assembled and tested."
4603 @section @code{.exitm}
4604 Exit early from the current macro definition. @xref{Macro}.
4607 @section @code{.extern}
4609 @cindex @code{extern} directive
4610 @code{.extern} is accepted in the source program---for compatibility
4611 with other assemblers---but it is ignored. @command{@value{AS}} treats
4612 all undefined symbols as external.
4615 @section @code{.fail @var{expression}}
4617 @cindex @code{fail} directive
4618 Generates an error or a warning. If the value of the @var{expression} is 500
4619 or more, @command{@value{AS}} will print a warning message. If the value is less
4620 than 500, @command{@value{AS}} will print an error message. The message will
4621 include the value of @var{expression}. This can occasionally be useful inside
4622 complex nested macros or conditional assembly.
4625 @section @code{.file}
4626 @cindex @code{file} directive
4628 @ifclear no-file-dir
4629 There are two different versions of the @code{.file} directive. Targets
4630 that support DWARF2 line number information use the DWARF2 version of
4631 @code{.file}. Other targets use the default version.
4633 @subheading Default Version
4635 @cindex logical file name
4636 @cindex file name, logical
4637 This version of the @code{.file} directive tells @command{@value{AS}} that we
4638 are about to start a new logical file. The syntax is:
4644 @var{string} is the new file name. In general, the filename is
4645 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4646 to specify an empty file name, you must give the quotes--@code{""}. This
4647 statement may go away in future: it is only recognized to be compatible with
4648 old @command{@value{AS}} programs.
4650 @subheading DWARF2 Version
4653 When emitting DWARF2 line number information, @code{.file} assigns filenames
4654 to the @code{.debug_line} file name table. The syntax is:
4657 .file @var{fileno} @var{filename}
4660 The @var{fileno} operand should be a unique positive integer to use as the
4661 index of the entry in the table. The @var{filename} operand is a C string
4664 The detail of filename indices is exposed to the user because the filename
4665 table is shared with the @code{.debug_info} section of the DWARF2 debugging
4666 information, and thus the user must know the exact indices that table
4670 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4672 @cindex @code{fill} directive
4673 @cindex writing patterns in memory
4674 @cindex patterns, writing in memory
4675 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4676 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4677 may be zero or more. @var{Size} may be zero or more, but if it is
4678 more than 8, then it is deemed to have the value 8, compatible with
4679 other people's assemblers. The contents of each @var{repeat} bytes
4680 is taken from an 8-byte number. The highest order 4 bytes are
4681 zero. The lowest order 4 bytes are @var{value} rendered in the
4682 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4683 Each @var{size} bytes in a repetition is taken from the lowest order
4684 @var{size} bytes of this number. Again, this bizarre behavior is
4685 compatible with other people's assemblers.
4687 @var{size} and @var{value} are optional.
4688 If the second comma and @var{value} are absent, @var{value} is
4689 assumed zero. If the first comma and following tokens are absent,
4690 @var{size} is assumed to be 1.
4693 @section @code{.float @var{flonums}}
4695 @cindex floating point numbers (single)
4696 @cindex @code{float} directive
4697 This directive assembles zero or more flonums, separated by commas. It
4698 has the same effect as @code{.single}.
4700 The exact kind of floating point numbers emitted depends on how
4701 @command{@value{AS}} is configured.
4702 @xref{Machine Dependencies}.
4706 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4707 in @sc{ieee} format.
4712 @section @code{.func @var{name}[,@var{label}]}
4713 @cindex @code{func} directive
4714 @code{.func} emits debugging information to denote function @var{name}, and
4715 is ignored unless the file is assembled with debugging enabled.
4716 Only @samp{--gstabs[+]} is currently supported.
4717 @var{label} is the entry point of the function and if omitted @var{name}
4718 prepended with the @samp{leading char} is used.
4719 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4720 All functions are currently defined to have @code{void} return type.
4721 The function must be terminated with @code{.endfunc}.
4724 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4726 @cindex @code{global} directive
4727 @cindex symbol, making visible to linker
4728 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4729 @var{symbol} in your partial program, its value is made available to
4730 other partial programs that are linked with it. Otherwise,
4731 @var{symbol} takes its attributes from a symbol of the same name
4732 from another file linked into the same program.
4734 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4735 compatibility with other assemblers.
4738 On the HPPA, @code{.global} is not always enough to make it accessible to other
4739 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4740 @xref{HPPA Directives, ,HPPA Assembler Directives}.
4745 @section @code{.gnu_attribute @var{tag},@var{value}}
4746 Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
4749 @section @code{.hidden @var{names}}
4751 @cindex @code{hidden} directive
4753 This is one of the ELF visibility directives. The other two are
4754 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4755 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4757 This directive overrides the named symbols default visibility (which is set by
4758 their binding: local, global or weak). The directive sets the visibility to
4759 @code{hidden} which means that the symbols are not visible to other components.
4760 Such symbols are always considered to be @code{protected} as well.
4764 @section @code{.hword @var{expressions}}
4766 @cindex @code{hword} directive
4767 @cindex integers, 16-bit
4768 @cindex numbers, 16-bit
4769 @cindex sixteen bit integers
4770 This expects zero or more @var{expressions}, and emits
4771 a 16 bit number for each.
4774 This directive is a synonym for @samp{.short}; depending on the target
4775 architecture, it may also be a synonym for @samp{.word}.
4779 This directive is a synonym for @samp{.short}.
4782 This directive is a synonym for both @samp{.short} and @samp{.word}.
4787 @section @code{.ident}
4789 @cindex @code{ident} directive
4791 This directive is used by some assemblers to place tags in object files. The
4792 behavior of this directive varies depending on the target. When using the
4793 a.out object file format, @command{@value{AS}} simply accepts the directive for
4794 source-file compatibility with existing assemblers, but does not emit anything
4795 for it. When using COFF, comments are emitted to the @code{.comment} or
4796 @code{.rdata} section, depending on the target. When using ELF, comments are
4797 emitted to the @code{.comment} section.
4800 @section @code{.if @var{absolute expression}}
4802 @cindex conditional assembly
4803 @cindex @code{if} directive
4804 @code{.if} marks the beginning of a section of code which is only
4805 considered part of the source program being assembled if the argument
4806 (which must be an @var{absolute expression}) is non-zero. The end of
4807 the conditional section of code must be marked by @code{.endif}
4808 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4809 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4810 If you have several conditions to check, @code{.elseif} may be used to avoid
4811 nesting blocks if/else within each subsequent @code{.else} block.
4813 The following variants of @code{.if} are also supported:
4815 @cindex @code{ifdef} directive
4816 @item .ifdef @var{symbol}
4817 Assembles the following section of code if the specified @var{symbol}
4818 has been defined. Note a symbol which has been referenced but not yet defined
4819 is considered to be undefined.
4821 @cindex @code{ifb} directive
4822 @item .ifb @var{text}
4823 Assembles the following section of code if the operand is blank (empty).
4825 @cindex @code{ifc} directive
4826 @item .ifc @var{string1},@var{string2}
4827 Assembles the following section of code if the two strings are the same. The
4828 strings may be optionally quoted with single quotes. If they are not quoted,
4829 the first string stops at the first comma, and the second string stops at the
4830 end of the line. Strings which contain whitespace should be quoted. The
4831 string comparison is case sensitive.
4833 @cindex @code{ifeq} directive
4834 @item .ifeq @var{absolute expression}
4835 Assembles the following section of code if the argument is zero.
4837 @cindex @code{ifeqs} directive
4838 @item .ifeqs @var{string1},@var{string2}
4839 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4841 @cindex @code{ifge} directive
4842 @item .ifge @var{absolute expression}
4843 Assembles the following section of code if the argument is greater than or
4846 @cindex @code{ifgt} directive
4847 @item .ifgt @var{absolute expression}
4848 Assembles the following section of code if the argument is greater than zero.
4850 @cindex @code{ifle} directive
4851 @item .ifle @var{absolute expression}
4852 Assembles the following section of code if the argument is less than or equal
4855 @cindex @code{iflt} directive
4856 @item .iflt @var{absolute expression}
4857 Assembles the following section of code if the argument is less than zero.
4859 @cindex @code{ifnb} directive
4860 @item .ifnb @var{text}
4861 Like @code{.ifb}, but the sense of the test is reversed: this assembles the
4862 following section of code if the operand is non-blank (non-empty).
4864 @cindex @code{ifnc} directive
4865 @item .ifnc @var{string1},@var{string2}.
4866 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4867 following section of code if the two strings are not the same.
4869 @cindex @code{ifndef} directive
4870 @cindex @code{ifnotdef} directive
4871 @item .ifndef @var{symbol}
4872 @itemx .ifnotdef @var{symbol}
4873 Assembles the following section of code if the specified @var{symbol}
4874 has not been defined. Both spelling variants are equivalent. Note a symbol
4875 which has been referenced but not yet defined is considered to be undefined.
4877 @cindex @code{ifne} directive
4878 @item .ifne @var{absolute expression}
4879 Assembles the following section of code if the argument is not equal to zero
4880 (in other words, this is equivalent to @code{.if}).
4882 @cindex @code{ifnes} directive
4883 @item .ifnes @var{string1},@var{string2}
4884 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4885 following section of code if the two strings are not the same.
4889 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4891 @cindex @code{incbin} directive
4892 @cindex binary files, including
4893 The @code{incbin} directive includes @var{file} verbatim at the current
4894 location. You can control the search paths used with the @samp{-I} command-line
4895 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4898 The @var{skip} argument skips a number of bytes from the start of the
4899 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4900 read. Note that the data is not aligned in any way, so it is the user's
4901 responsibility to make sure that proper alignment is provided both before and
4902 after the @code{incbin} directive.
4905 @section @code{.include "@var{file}"}
4907 @cindex @code{include} directive
4908 @cindex supporting files, including
4909 @cindex files, including
4910 This directive provides a way to include supporting files at specified
4911 points in your source program. The code from @var{file} is assembled as
4912 if it followed the point of the @code{.include}; when the end of the
4913 included file is reached, assembly of the original file continues. You
4914 can control the search paths used with the @samp{-I} command-line option
4915 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4919 @section @code{.int @var{expressions}}
4921 @cindex @code{int} directive
4922 @cindex integers, 32-bit
4923 Expect zero or more @var{expressions}, of any section, separated by commas.
4924 For each expression, emit a number that, at run time, is the value of that
4925 expression. The byte order and bit size of the number depends on what kind
4926 of target the assembly is for.
4930 On most forms of the H8/300, @code{.int} emits 16-bit
4931 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
4938 @section @code{.internal @var{names}}
4940 @cindex @code{internal} directive
4942 This is one of the ELF visibility directives. The other two are
4943 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4944 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4946 This directive overrides the named symbols default visibility (which is set by
4947 their binding: local, global or weak). The directive sets the visibility to
4948 @code{internal} which means that the symbols are considered to be @code{hidden}
4949 (i.e., not visible to other components), and that some extra, processor specific
4950 processing must also be performed upon the symbols as well.
4954 @section @code{.irp @var{symbol},@var{values}}@dots{}
4956 @cindex @code{irp} directive
4957 Evaluate a sequence of statements assigning different values to @var{symbol}.
4958 The sequence of statements starts at the @code{.irp} directive, and is
4959 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4960 set to @var{value}, and the sequence of statements is assembled. If no
4961 @var{value} is listed, the sequence of statements is assembled once, with
4962 @var{symbol} set to the null string. To refer to @var{symbol} within the
4963 sequence of statements, use @var{\symbol}.
4965 For example, assembling
4973 is equivalent to assembling
4981 For some caveats with the spelling of @var{symbol}, see also @ref{Macro}.
4984 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4986 @cindex @code{irpc} directive
4987 Evaluate a sequence of statements assigning different values to @var{symbol}.
4988 The sequence of statements starts at the @code{.irpc} directive, and is
4989 terminated by an @code{.endr} directive. For each character in @var{value},
4990 @var{symbol} is set to the character, and the sequence of statements is
4991 assembled. If no @var{value} is listed, the sequence of statements is
4992 assembled once, with @var{symbol} set to the null string. To refer to
4993 @var{symbol} within the sequence of statements, use @var{\symbol}.
4995 For example, assembling
5003 is equivalent to assembling
5011 For some caveats with the spelling of @var{symbol}, see also the discussion
5015 @section @code{.lcomm @var{symbol} , @var{length}}
5017 @cindex @code{lcomm} directive
5018 @cindex local common symbols
5019 @cindex symbols, local common
5020 Reserve @var{length} (an absolute expression) bytes for a local common
5021 denoted by @var{symbol}. The section and value of @var{symbol} are
5022 those of the new local common. The addresses are allocated in the bss
5023 section, so that at run-time the bytes start off zeroed. @var{Symbol}
5024 is not declared global (@pxref{Global,,@code{.global}}), so is normally
5025 not visible to @code{@value{LD}}.
5028 Some targets permit a third argument to be used with @code{.lcomm}. This
5029 argument specifies the desired alignment of the symbol in the bss section.
5033 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
5034 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
5038 @section @code{.lflags}
5040 @cindex @code{lflags} directive (ignored)
5041 @command{@value{AS}} accepts this directive, for compatibility with other
5042 assemblers, but ignores it.
5044 @ifclear no-line-dir
5046 @section @code{.line @var{line-number}}
5048 @cindex @code{line} directive
5049 @cindex logical line number
5051 Change the logical line number. @var{line-number} must be an absolute
5052 expression. The next line has that logical line number. Therefore any other
5053 statements on the current line (after a statement separator character) are
5054 reported as on logical line number @var{line-number} @minus{} 1. One day
5055 @command{@value{AS}} will no longer support this directive: it is recognized only
5056 for compatibility with existing assembler programs.
5059 Even though this is a directive associated with the @code{a.out} or
5060 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
5061 when producing COFF output, and treats @samp{.line} as though it
5062 were the COFF @samp{.ln} @emph{if} it is found outside a
5063 @code{.def}/@code{.endef} pair.
5065 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
5066 used by compilers to generate auxiliary symbol information for
5071 @section @code{.linkonce [@var{type}]}
5073 @cindex @code{linkonce} directive
5074 @cindex common sections
5075 Mark the current section so that the linker only includes a single copy of it.
5076 This may be used to include the same section in several different object files,
5077 but ensure that the linker will only include it once in the final output file.
5078 The @code{.linkonce} pseudo-op must be used for each instance of the section.
5079 Duplicate sections are detected based on the section name, so it should be
5082 This directive is only supported by a few object file formats; as of this
5083 writing, the only object file format which supports it is the Portable
5084 Executable format used on Windows NT.
5086 The @var{type} argument is optional. If specified, it must be one of the
5087 following strings. For example:
5091 Not all types may be supported on all object file formats.
5095 Silently discard duplicate sections. This is the default.
5098 Warn if there are duplicate sections, but still keep only one copy.
5101 Warn if any of the duplicates have different sizes.
5104 Warn if any of the duplicates do not have exactly the same contents.
5108 @section @code{.list}
5110 @cindex @code{list} directive
5111 @cindex listing control, turning on
5112 Control (in conjunction with the @code{.nolist} directive) whether or
5113 not assembly listings are generated. These two directives maintain an
5114 internal counter (which is zero initially). @code{.list} increments the
5115 counter, and @code{.nolist} decrements it. Assembly listings are
5116 generated whenever the counter is greater than zero.
5118 By default, listings are disabled. When you enable them (with the
5119 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
5120 the initial value of the listing counter is one.
5123 @section @code{.ln @var{line-number}}
5125 @cindex @code{ln} directive
5126 @ifclear no-line-dir
5127 @samp{.ln} is a synonym for @samp{.line}.
5130 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
5131 must be an absolute expression. The next line has that logical
5132 line number, so any other statements on the current line (after a
5133 statement separator character @code{;}) are reported as on logical
5134 line number @var{line-number} @minus{} 1.
5137 This directive is accepted, but ignored, when @command{@value{AS}} is
5138 configured for @code{b.out}; its effect is only associated with COFF
5144 @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]}
5145 @cindex @code{loc} directive
5146 When emitting DWARF2 line number information,
5147 the @code{.loc} directive will add a row to the @code{.debug_line} line
5148 number matrix corresponding to the immediately following assembly
5149 instruction. The @var{fileno}, @var{lineno}, and optional @var{column}
5150 arguments will be applied to the @code{.debug_line} state machine before
5153 The @var{options} are a sequence of the following tokens in any order:
5157 This option will set the @code{basic_block} register in the
5158 @code{.debug_line} state machine to @code{true}.
5161 This option will set the @code{prologue_end} register in the
5162 @code{.debug_line} state machine to @code{true}.
5164 @item epilogue_begin
5165 This option will set the @code{epilogue_begin} register in the
5166 @code{.debug_line} state machine to @code{true}.
5168 @item is_stmt @var{value}
5169 This option will set the @code{is_stmt} register in the
5170 @code{.debug_line} state machine to @code{value}, which must be
5173 @item isa @var{value}
5174 This directive will set the @code{isa} register in the @code{.debug_line}
5175 state machine to @var{value}, which must be an unsigned integer.
5177 @item discriminator @var{value}
5178 This directive will set the @code{discriminator} register in the @code{.debug_line}
5179 state machine to @var{value}, which must be an unsigned integer.
5183 @node Loc_mark_labels
5184 @section @code{.loc_mark_labels @var{enable}}
5185 @cindex @code{loc_mark_labels} directive
5186 When emitting DWARF2 line number information,
5187 the @code{.loc_mark_labels} directive makes the assembler emit an entry
5188 to the @code{.debug_line} line number matrix with the @code{basic_block}
5189 register in the state machine set whenever a code label is seen.
5190 The @var{enable} argument should be either 1 or 0, to enable or disable
5191 this function respectively.
5195 @section @code{.local @var{names}}
5197 @cindex @code{local} directive
5198 This directive, which is available for ELF targets, marks each symbol in
5199 the comma-separated list of @code{names} as a local symbol so that it
5200 will not be externally visible. If the symbols do not already exist,
5201 they will be created.
5203 For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not
5204 accept an alignment argument, which is the case for most ELF targets,
5205 the @code{.local} directive can be used in combination with @code{.comm}
5206 (@pxref{Comm}) to define aligned local common data.
5210 @section @code{.long @var{expressions}}
5212 @cindex @code{long} directive
5213 @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}.
5216 @c no one seems to know what this is for or whether this description is
5217 @c what it really ought to do
5219 @section @code{.lsym @var{symbol}, @var{expression}}
5221 @cindex @code{lsym} directive
5222 @cindex symbol, not referenced in assembly
5223 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
5224 the hash table, ensuring it cannot be referenced by name during the
5225 rest of the assembly. This sets the attributes of the symbol to be
5226 the same as the expression value:
5228 @var{other} = @var{descriptor} = 0
5229 @var{type} = @r{(section of @var{expression})}
5230 @var{value} = @var{expression}
5233 The new symbol is not flagged as external.
5237 @section @code{.macro}
5240 The commands @code{.macro} and @code{.endm} allow you to define macros that
5241 generate assembly output. For example, this definition specifies a macro
5242 @code{sum} that puts a sequence of numbers into memory:
5245 .macro sum from=0, to=5
5254 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
5266 @item .macro @var{macname}
5267 @itemx .macro @var{macname} @var{macargs} @dots{}
5268 @cindex @code{macro} directive
5269 Begin the definition of a macro called @var{macname}. If your macro
5270 definition requires arguments, specify their names after the macro name,
5271 separated by commas or spaces. You can qualify the macro argument to
5272 indicate whether all invocations must specify a non-blank value (through
5273 @samp{:@code{req}}), or whether it takes all of the remaining arguments
5274 (through @samp{:@code{vararg}}). You can supply a default value for any
5275 macro argument by following the name with @samp{=@var{deflt}}. You
5276 cannot define two macros with the same @var{macname} unless it has been
5277 subject to the @code{.purgem} directive (@pxref{Purgem}) between the two
5278 definitions. For example, these are all valid @code{.macro} statements:
5282 Begin the definition of a macro called @code{comm}, which takes no
5285 @item .macro plus1 p, p1
5286 @itemx .macro plus1 p p1
5287 Either statement begins the definition of a macro called @code{plus1},
5288 which takes two arguments; within the macro definition, write
5289 @samp{\p} or @samp{\p1} to evaluate the arguments.
5291 @item .macro reserve_str p1=0 p2
5292 Begin the definition of a macro called @code{reserve_str}, with two
5293 arguments. The first argument has a default value, but not the second.
5294 After the definition is complete, you can call the macro either as
5295 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
5296 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
5297 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
5298 @samp{0}, and @samp{\p2} evaluating to @var{b}).
5300 @item .macro m p1:req, p2=0, p3:vararg
5301 Begin the definition of a macro called @code{m}, with at least three
5302 arguments. The first argument must always have a value specified, but
5303 not the second, which instead has a default value. The third formal
5304 will get assigned all remaining arguments specified at invocation time.
5306 When you call a macro, you can specify the argument values either by
5307 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
5308 @samp{sum to=17, from=9}.
5312 Note that since each of the @var{macargs} can be an identifier exactly
5313 as any other one permitted by the target architecture, there may be
5314 occasional problems if the target hand-crafts special meanings to certain
5315 characters when they occur in a special position. For example, if the colon
5316 (@code{:}) is generally permitted to be part of a symbol name, but the
5317 architecture specific code special-cases it when occurring as the final
5318 character of a symbol (to denote a label), then the macro parameter
5319 replacement code will have no way of knowing that and consider the whole
5320 construct (including the colon) an identifier, and check only this
5321 identifier for being the subject to parameter substitution. So for example
5322 this macro definition:
5330 might not work as expected. Invoking @samp{label foo} might not create a label
5331 called @samp{foo} but instead just insert the text @samp{\l:} into the
5332 assembler source, probably generating an error about an unrecognised
5335 Similarly problems might occur with the period character (@samp{.})
5336 which is often allowed inside opcode names (and hence identifier names). So
5337 for example constructing a macro to build an opcode from a base name and a
5338 length specifier like this:
5341 .macro opcode base length
5346 and invoking it as @samp{opcode store l} will not create a @samp{store.l}
5347 instruction but instead generate some kind of error as the assembler tries to
5348 interpret the text @samp{\base.\length}.
5350 There are several possible ways around this problem:
5353 @item Insert white space
5354 If it is possible to use white space characters then this is the simplest
5363 @item Use @samp{\()}
5364 The string @samp{\()} can be used to separate the end of a macro argument from
5365 the following text. eg:
5368 .macro opcode base length
5373 @item Use the alternate macro syntax mode
5374 In the alternative macro syntax mode the ampersand character (@samp{&}) can be
5375 used as a separator. eg:
5385 Note: this problem of correctly identifying string parameters to pseudo ops
5386 also applies to the identifiers used in @code{.irp} (@pxref{Irp})
5387 and @code{.irpc} (@pxref{Irpc}) as well.
5390 @cindex @code{endm} directive
5391 Mark the end of a macro definition.
5394 @cindex @code{exitm} directive
5395 Exit early from the current macro definition.
5397 @cindex number of macros executed
5398 @cindex macros, count executed
5400 @command{@value{AS}} maintains a counter of how many macros it has
5401 executed in this pseudo-variable; you can copy that number to your
5402 output with @samp{\@@}, but @emph{only within a macro definition}.
5404 @item LOCAL @var{name} [ , @dots{} ]
5405 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
5406 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
5407 @xref{Altmacro,,@code{.altmacro}}.
5411 @section @code{.mri @var{val}}
5413 @cindex @code{mri} directive
5414 @cindex MRI mode, temporarily
5415 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
5416 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
5417 affects code assembled until the next @code{.mri} directive, or until the end
5418 of the file. @xref{M, MRI mode, MRI mode}.
5421 @section @code{.noaltmacro}
5422 Disable alternate macro mode. @xref{Altmacro}.
5425 @section @code{.nolist}
5427 @cindex @code{nolist} directive
5428 @cindex listing control, turning off
5429 Control (in conjunction with the @code{.list} directive) whether or
5430 not assembly listings are generated. These two directives maintain an
5431 internal counter (which is zero initially). @code{.list} increments the
5432 counter, and @code{.nolist} decrements it. Assembly listings are
5433 generated whenever the counter is greater than zero.
5436 @section @code{.octa @var{bignums}}
5438 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
5439 @cindex @code{octa} directive
5440 @cindex integer, 16-byte
5441 @cindex sixteen byte integer
5442 This directive expects zero or more bignums, separated by commas. For each
5443 bignum, it emits a 16-byte integer.
5445 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
5446 hence @emph{octa}-word for 16 bytes.
5449 @section @code{.org @var{new-lc} , @var{fill}}
5451 @cindex @code{org} directive
5452 @cindex location counter, advancing
5453 @cindex advancing location counter
5454 @cindex current address, advancing
5455 Advance the location counter of the current section to
5456 @var{new-lc}. @var{new-lc} is either an absolute expression or an
5457 expression with the same section as the current subsection. That is,
5458 you can't use @code{.org} to cross sections: if @var{new-lc} has the
5459 wrong section, the @code{.org} directive is ignored. To be compatible
5460 with former assemblers, if the section of @var{new-lc} is absolute,
5461 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
5462 is the same as the current subsection.
5464 @code{.org} may only increase the location counter, or leave it
5465 unchanged; you cannot use @code{.org} to move the location counter
5468 @c double negative used below "not undefined" because this is a specific
5469 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
5470 @c section. doc@cygnus.com 18feb91
5471 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
5472 may not be undefined. If you really detest this restriction we eagerly await
5473 a chance to share your improved assembler.
5475 Beware that the origin is relative to the start of the section, not
5476 to the start of the subsection. This is compatible with other
5477 people's assemblers.
5479 When the location counter (of the current subsection) is advanced, the
5480 intervening bytes are filled with @var{fill} which should be an
5481 absolute expression. If the comma and @var{fill} are omitted,
5482 @var{fill} defaults to zero.
5485 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
5487 @cindex padding the location counter given a power of two
5488 @cindex @code{p2align} directive
5489 Pad the location counter (in the current subsection) to a particular
5490 storage boundary. The first expression (which must be absolute) is the
5491 number of low-order zero bits the location counter must have after
5492 advancement. For example @samp{.p2align 3} advances the location
5493 counter until it a multiple of 8. If the location counter is already a
5494 multiple of 8, no change is needed.
5496 The second expression (also absolute) gives the fill value to be stored in the
5497 padding bytes. It (and the comma) may be omitted. If it is omitted, the
5498 padding bytes are normally zero. However, on some systems, if the section is
5499 marked as containing code and the fill value is omitted, the space is filled
5500 with no-op instructions.
5502 The third expression is also absolute, and is also optional. If it is present,
5503 it is the maximum number of bytes that should be skipped by this alignment
5504 directive. If doing the alignment would require skipping more bytes than the
5505 specified maximum, then the alignment is not done at all. You can omit the
5506 fill value (the second argument) entirely by simply using two commas after the
5507 required alignment; this can be useful if you want the alignment to be filled
5508 with no-op instructions when appropriate.
5510 @cindex @code{p2alignw} directive
5511 @cindex @code{p2alignl} directive
5512 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5513 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5514 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5515 fill pattern as a four byte longword value. For example, @code{.p2alignw
5516 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5517 filled in with the value 0x368d (the exact placement of the bytes depends upon
5518 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5523 @section @code{.popsection}
5525 @cindex @code{popsection} directive
5526 @cindex Section Stack
5527 This is one of the ELF section stack manipulation directives. The others are
5528 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5529 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5532 This directive replaces the current section (and subsection) with the top
5533 section (and subsection) on the section stack. This section is popped off the
5539 @section @code{.previous}
5541 @cindex @code{previous} directive
5542 @cindex Section Stack
5543 This is one of the ELF section stack manipulation directives. The others are
5544 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5545 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5546 (@pxref{PopSection}).
5548 This directive swaps the current section (and subsection) with most recently
5549 referenced section/subsection pair prior to this one. Multiple
5550 @code{.previous} directives in a row will flip between two sections (and their
5551 subsections). For example:
5563 Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
5569 # Now in section A subsection 1
5573 # Now in section B subsection 0
5576 # Now in section B subsection 1
5579 # Now in section B subsection 0
5583 Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
5584 section B and 0x9abc into subsection 1 of section B.
5586 In terms of the section stack, this directive swaps the current section with
5587 the top section on the section stack.
5591 @section @code{.print @var{string}}
5593 @cindex @code{print} directive
5594 @command{@value{AS}} will print @var{string} on the standard output during
5595 assembly. You must put @var{string} in double quotes.
5599 @section @code{.protected @var{names}}
5601 @cindex @code{protected} directive
5603 This is one of the ELF visibility directives. The other two are
5604 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
5606 This directive overrides the named symbols default visibility (which is set by
5607 their binding: local, global or weak). The directive sets the visibility to
5608 @code{protected} which means that any references to the symbols from within the
5609 components that defines them must be resolved to the definition in that
5610 component, even if a definition in another component would normally preempt
5615 @section @code{.psize @var{lines} , @var{columns}}
5617 @cindex @code{psize} directive
5618 @cindex listing control: paper size
5619 @cindex paper size, for listings
5620 Use this directive to declare the number of lines---and, optionally, the
5621 number of columns---to use for each page, when generating listings.
5623 If you do not use @code{.psize}, listings use a default line-count
5624 of 60. You may omit the comma and @var{columns} specification; the
5625 default width is 200 columns.
5627 @command{@value{AS}} generates formfeeds whenever the specified number of
5628 lines is exceeded (or whenever you explicitly request one, using
5631 If you specify @var{lines} as @code{0}, no formfeeds are generated save
5632 those explicitly specified with @code{.eject}.
5635 @section @code{.purgem @var{name}}
5637 @cindex @code{purgem} directive
5638 Undefine the macro @var{name}, so that later uses of the string will not be
5639 expanded. @xref{Macro}.
5643 @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]}
5645 @cindex @code{pushsection} directive
5646 @cindex Section Stack
5647 This is one of the ELF section stack manipulation directives. The others are
5648 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5649 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5652 This directive pushes the current section (and subsection) onto the
5653 top of the section stack, and then replaces the current section and
5654 subsection with @code{name} and @code{subsection}. The optional
5655 @code{flags}, @code{type} and @code{arguments} are treated the same
5656 as in the @code{.section} (@pxref{Section}) directive.
5660 @section @code{.quad @var{bignums}}
5662 @cindex @code{quad} directive
5663 @code{.quad} expects zero or more bignums, separated by commas. For
5664 each bignum, it emits
5666 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
5667 warning message; and just takes the lowest order 8 bytes of the bignum.
5668 @cindex eight-byte integer
5669 @cindex integer, 8-byte
5671 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
5672 hence @emph{quad}-word for 8 bytes.
5675 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
5676 warning message; and just takes the lowest order 16 bytes of the bignum.
5677 @cindex sixteen-byte integer
5678 @cindex integer, 16-byte
5682 @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
5684 @cindex @code{reloc} directive
5685 Generate a relocation at @var{offset} of type @var{reloc_name} with value
5686 @var{expression}. If @var{offset} is a number, the relocation is generated in
5687 the current section. If @var{offset} is an expression that resolves to a
5688 symbol plus offset, the relocation is generated in the given symbol's section.
5689 @var{expression}, if present, must resolve to a symbol plus addend or to an
5690 absolute value, but note that not all targets support an addend. e.g. ELF REL
5691 targets such as i386 store an addend in the section contents rather than in the
5692 relocation. This low level interface does not support addends stored in the
5696 @section @code{.rept @var{count}}
5698 @cindex @code{rept} directive
5699 Repeat the sequence of lines between the @code{.rept} directive and the next
5700 @code{.endr} directive @var{count} times.
5702 For example, assembling
5710 is equivalent to assembling
5719 @section @code{.sbttl "@var{subheading}"}
5721 @cindex @code{sbttl} directive
5722 @cindex subtitles for listings
5723 @cindex listing control: subtitle
5724 Use @var{subheading} as the title (third line, immediately after the
5725 title line) when generating assembly listings.
5727 This directive affects subsequent pages, as well as the current page if
5728 it appears within ten lines of the top of a page.
5732 @section @code{.scl @var{class}}
5734 @cindex @code{scl} directive
5735 @cindex symbol storage class (COFF)
5736 @cindex COFF symbol storage class
5737 Set the storage-class value for a symbol. This directive may only be
5738 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
5739 whether a symbol is static or external, or it may record further
5740 symbolic debugging information.
5743 The @samp{.scl} directive is primarily associated with COFF output; when
5744 configured to generate @code{b.out} output format, @command{@value{AS}}
5745 accepts this directive but ignores it.
5751 @section @code{.section @var{name}}
5753 @cindex named section
5754 Use the @code{.section} directive to assemble the following code into a section
5757 This directive is only supported for targets that actually support arbitrarily
5758 named sections; on @code{a.out} targets, for example, it is not accepted, even
5759 with a standard @code{a.out} section name.
5763 @c only print the extra heading if both COFF and ELF are set
5764 @subheading COFF Version
5767 @cindex @code{section} directive (COFF version)
5768 For COFF targets, the @code{.section} directive is used in one of the following
5772 .section @var{name}[, "@var{flags}"]
5773 .section @var{name}[, @var{subsection}]
5776 If the optional argument is quoted, it is taken as flags to use for the
5777 section. Each flag is a single character. The following flags are recognized:
5780 bss section (uninitialized data)
5782 section is not loaded
5792 shared section (meaningful for PE targets)
5794 ignored. (For compatibility with the ELF version)
5796 section is not readable (meaningful for PE targets)
5798 single-digit power-of-two section alignment (GNU extension)
5801 If no flags are specified, the default flags depend upon the section name. If
5802 the section name is not recognized, the default will be for the section to be
5803 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
5804 from the section, rather than adding them, so if they are used on their own it
5805 will be as if no flags had been specified at all.
5807 If the optional argument to the @code{.section} directive is not quoted, it is
5808 taken as a subsection number (@pxref{Sub-Sections}).
5813 @c only print the extra heading if both COFF and ELF are set
5814 @subheading ELF Version
5817 @cindex Section Stack
5818 This is one of the ELF section stack manipulation directives. The others are
5819 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5820 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5821 @code{.previous} (@pxref{Previous}).
5823 @cindex @code{section} directive (ELF version)
5824 For ELF targets, the @code{.section} directive is used like this:
5827 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]]
5830 The optional @var{flags} argument is a quoted string which may contain any
5831 combination of the following characters:
5834 section is allocatable
5838 section is executable
5840 section is mergeable
5842 section contains zero terminated strings
5844 section is a member of a section group
5846 section is used for thread-local-storage
5849 The optional @var{type} argument may contain one of the following constants:
5852 section contains data
5854 section does not contain data (i.e., section only occupies space)
5856 section contains data which is used by things other than the program
5858 section contains an array of pointers to init functions
5860 section contains an array of pointers to finish functions
5861 @item @@preinit_array
5862 section contains an array of pointers to pre-init functions
5865 Many targets only support the first three section types.
5867 Note on targets where the @code{@@} character is the start of a comment (eg
5868 ARM) then another character is used instead. For example the ARM port uses the
5871 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
5872 be specified as well as an extra argument---@var{entsize}---like this:
5875 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
5878 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
5879 constants, each @var{entsize} octets long. Sections with both @code{M} and
5880 @code{S} must contain zero terminated strings where each character is
5881 @var{entsize} bytes long. The linker may remove duplicates within sections with
5882 the same name, same entity size and same flags. @var{entsize} must be an
5883 absolute expression. For sections with both @code{M} and @code{S}, a string
5884 which is a suffix of a larger string is considered a duplicate. Thus
5885 @code{"def"} will be merged with @code{"abcdef"}; A reference to the first
5886 @code{"def"} will be changed to a reference to @code{"abcdef"+3}.
5888 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
5889 be present along with an additional field like this:
5892 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
5895 The @var{GroupName} field specifies the name of the section group to which this
5896 particular section belongs. The optional linkage field can contain:
5899 indicates that only one copy of this section should be retained
5904 Note: if both the @var{M} and @var{G} flags are present then the fields for
5905 the Merge flag should come first, like this:
5908 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
5911 If no flags are specified, the default flags depend upon the section name. If
5912 the section name is not recognized, the default will be for the section to have
5913 none of the above flags: it will not be allocated in memory, nor writable, nor
5914 executable. The section will contain data.
5916 For ELF targets, the assembler supports another type of @code{.section}
5917 directive for compatibility with the Solaris assembler:
5920 .section "@var{name}"[, @var{flags}...]
5923 Note that the section name is quoted. There may be a sequence of comma
5927 section is allocatable
5931 section is executable
5933 section is used for thread local storage
5936 This directive replaces the current section and subsection. See the
5937 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
5938 some examples of how this directive and the other section stack directives
5944 @section @code{.set @var{symbol}, @var{expression}}
5946 @cindex @code{set} directive
5947 @cindex symbol value, setting
5948 Set the value of @var{symbol} to @var{expression}. This
5949 changes @var{symbol}'s value and type to conform to
5950 @var{expression}. If @var{symbol} was flagged as external, it remains
5951 flagged (@pxref{Symbol Attributes}).
5953 You may @code{.set} a symbol many times in the same assembly.
5955 If you @code{.set} a global symbol, the value stored in the object
5956 file is the last value stored into it.
5959 On Z80 @code{set} is a real instruction, use
5960 @samp{@var{symbol} defl @var{expression}} instead.
5964 @section @code{.short @var{expressions}}
5966 @cindex @code{short} directive
5968 @code{.short} is normally the same as @samp{.word}.
5969 @xref{Word,,@code{.word}}.
5971 In some configurations, however, @code{.short} and @code{.word} generate
5972 numbers of different lengths. @xref{Machine Dependencies}.
5976 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5979 This expects zero or more @var{expressions}, and emits
5980 a 16 bit number for each.
5985 @section @code{.single @var{flonums}}
5987 @cindex @code{single} directive
5988 @cindex floating point numbers (single)
5989 This directive assembles zero or more flonums, separated by commas. It
5990 has the same effect as @code{.float}.
5992 The exact kind of floating point numbers emitted depends on how
5993 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5997 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5998 numbers in @sc{ieee} format.
6004 @section @code{.size}
6006 This directive is used to set the size associated with a symbol.
6010 @c only print the extra heading if both COFF and ELF are set
6011 @subheading COFF Version
6014 @cindex @code{size} directive (COFF version)
6015 For COFF targets, the @code{.size} directive is only permitted inside
6016 @code{.def}/@code{.endef} pairs. It is used like this:
6019 .size @var{expression}
6023 @samp{.size} is only meaningful when generating COFF format output; when
6024 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6031 @c only print the extra heading if both COFF and ELF are set
6032 @subheading ELF Version
6035 @cindex @code{size} directive (ELF version)
6036 For ELF targets, the @code{.size} directive is used like this:
6039 .size @var{name} , @var{expression}
6042 This directive sets the size associated with a symbol @var{name}.
6043 The size in bytes is computed from @var{expression} which can make use of label
6044 arithmetic. This directive is typically used to set the size of function
6049 @ifclear no-space-dir
6051 @section @code{.skip @var{size} , @var{fill}}
6053 @cindex @code{skip} directive
6054 @cindex filling memory
6055 This directive emits @var{size} bytes, each of value @var{fill}. Both
6056 @var{size} and @var{fill} are absolute expressions. If the comma and
6057 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
6062 @section @code{.sleb128 @var{expressions}}
6064 @cindex @code{sleb128} directive
6065 @var{sleb128} stands for ``signed little endian base 128.'' This is a
6066 compact, variable length representation of numbers used by the DWARF
6067 symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}.
6069 @ifclear no-space-dir
6071 @section @code{.space @var{size} , @var{fill}}
6073 @cindex @code{space} directive
6074 @cindex filling memory
6075 This directive emits @var{size} bytes, each of value @var{fill}. Both
6076 @var{size} and @var{fill} are absolute expressions. If the comma
6077 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
6082 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
6083 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
6084 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
6085 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
6093 @section @code{.stabd, .stabn, .stabs}
6095 @cindex symbolic debuggers, information for
6096 @cindex @code{stab@var{x}} directives
6097 There are three directives that begin @samp{.stab}.
6098 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
6099 The symbols are not entered in the @command{@value{AS}} hash table: they
6100 cannot be referenced elsewhere in the source file.
6101 Up to five fields are required:
6105 This is the symbol's name. It may contain any character except
6106 @samp{\000}, so is more general than ordinary symbol names. Some
6107 debuggers used to code arbitrarily complex structures into symbol names
6111 An absolute expression. The symbol's type is set to the low 8 bits of
6112 this expression. Any bit pattern is permitted, but @code{@value{LD}}
6113 and debuggers choke on silly bit patterns.
6116 An absolute expression. The symbol's ``other'' attribute is set to the
6117 low 8 bits of this expression.
6120 An absolute expression. The symbol's descriptor is set to the low 16
6121 bits of this expression.
6124 An absolute expression which becomes the symbol's value.
6127 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
6128 or @code{.stabs} statement, the symbol has probably already been created;
6129 you get a half-formed symbol in your object file. This is
6130 compatible with earlier assemblers!
6133 @cindex @code{stabd} directive
6134 @item .stabd @var{type} , @var{other} , @var{desc}
6136 The ``name'' of the symbol generated is not even an empty string.
6137 It is a null pointer, for compatibility. Older assemblers used a
6138 null pointer so they didn't waste space in object files with empty
6141 The symbol's value is set to the location counter,
6142 relocatably. When your program is linked, the value of this symbol
6143 is the address of the location counter when the @code{.stabd} was
6146 @cindex @code{stabn} directive
6147 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
6148 The name of the symbol is set to the empty string @code{""}.
6150 @cindex @code{stabs} directive
6151 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
6152 All five fields are specified.
6158 @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
6159 "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
6161 @cindex string, copying to object file
6162 @cindex string8, copying to object file
6163 @cindex string16, copying to object file
6164 @cindex string32, copying to object file
6165 @cindex string64, copying to object file
6166 @cindex @code{string} directive
6167 @cindex @code{string8} directive
6168 @cindex @code{string16} directive
6169 @cindex @code{string32} directive
6170 @cindex @code{string64} directive
6172 Copy the characters in @var{str} to the object file. You may specify more than
6173 one string to copy, separated by commas. Unless otherwise specified for a
6174 particular machine, the assembler marks the end of each string with a 0 byte.
6175 You can use any of the escape sequences described in @ref{Strings,,Strings}.
6177 The variants @code{string16}, @code{string32} and @code{string64} differ from
6178 the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
6179 copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
6180 are stored in target endianness byte order.
6186 .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
6187 .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
6192 @section @code{.struct @var{expression}}
6194 @cindex @code{struct} directive
6195 Switch to the absolute section, and set the section offset to @var{expression},
6196 which must be an absolute expression. You might use this as follows:
6205 This would define the symbol @code{field1} to have the value 0, the symbol
6206 @code{field2} to have the value 4, and the symbol @code{field3} to have the
6207 value 8. Assembly would be left in the absolute section, and you would need to
6208 use a @code{.section} directive of some sort to change to some other section
6209 before further assembly.
6213 @section @code{.subsection @var{name}}
6215 @cindex @code{subsection} directive
6216 @cindex Section Stack
6217 This is one of the ELF section stack manipulation directives. The others are
6218 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
6219 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6222 This directive replaces the current subsection with @code{name}. The current
6223 section is not changed. The replaced subsection is put onto the section stack
6224 in place of the then current top of stack subsection.
6229 @section @code{.symver}
6230 @cindex @code{symver} directive
6231 @cindex symbol versioning
6232 @cindex versions of symbols
6233 Use the @code{.symver} directive to bind symbols to specific version nodes
6234 within a source file. This is only supported on ELF platforms, and is
6235 typically used when assembling files to be linked into a shared library.
6236 There are cases where it may make sense to use this in objects to be bound
6237 into an application itself so as to override a versioned symbol from a
6240 For ELF targets, the @code{.symver} directive can be used like this:
6242 .symver @var{name}, @var{name2@@nodename}
6244 If the symbol @var{name} is defined within the file
6245 being assembled, the @code{.symver} directive effectively creates a symbol
6246 alias with the name @var{name2@@nodename}, and in fact the main reason that we
6247 just don't try and create a regular alias is that the @var{@@} character isn't
6248 permitted in symbol names. The @var{name2} part of the name is the actual name
6249 of the symbol by which it will be externally referenced. The name @var{name}
6250 itself is merely a name of convenience that is used so that it is possible to
6251 have definitions for multiple versions of a function within a single source
6252 file, and so that the compiler can unambiguously know which version of a
6253 function is being mentioned. The @var{nodename} portion of the alias should be
6254 the name of a node specified in the version script supplied to the linker when
6255 building a shared library. If you are attempting to override a versioned
6256 symbol from a shared library, then @var{nodename} should correspond to the
6257 nodename of the symbol you are trying to override.
6259 If the symbol @var{name} is not defined within the file being assembled, all
6260 references to @var{name} will be changed to @var{name2@@nodename}. If no
6261 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
6264 Another usage of the @code{.symver} directive is:
6266 .symver @var{name}, @var{name2@@@@nodename}
6268 In this case, the symbol @var{name} must exist and be defined within
6269 the file being assembled. It is similar to @var{name2@@nodename}. The
6270 difference is @var{name2@@@@nodename} will also be used to resolve
6271 references to @var{name2} by the linker.
6273 The third usage of the @code{.symver} directive is:
6275 .symver @var{name}, @var{name2@@@@@@nodename}
6277 When @var{name} is not defined within the
6278 file being assembled, it is treated as @var{name2@@nodename}. When
6279 @var{name} is defined within the file being assembled, the symbol
6280 name, @var{name}, will be changed to @var{name2@@@@nodename}.
6285 @section @code{.tag @var{structname}}
6287 @cindex COFF structure debugging
6288 @cindex structure debugging, COFF
6289 @cindex @code{tag} directive
6290 This directive is generated by compilers to include auxiliary debugging
6291 information in the symbol table. It is only permitted inside
6292 @code{.def}/@code{.endef} pairs. Tags are used to link structure
6293 definitions in the symbol table with instances of those structures.
6296 @samp{.tag} is only used when generating COFF format output; when
6297 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6303 @section @code{.text @var{subsection}}
6305 @cindex @code{text} directive
6306 Tells @command{@value{AS}} to assemble the following statements onto the end of
6307 the text subsection numbered @var{subsection}, which is an absolute
6308 expression. If @var{subsection} is omitted, subsection number zero
6312 @section @code{.title "@var{heading}"}
6314 @cindex @code{title} directive
6315 @cindex listing control: title line
6316 Use @var{heading} as the title (second line, immediately after the
6317 source file name and pagenumber) when generating assembly listings.
6319 This directive affects subsequent pages, as well as the current page if
6320 it appears within ten lines of the top of a page.
6324 @section @code{.type}
6326 This directive is used to set the type of a symbol.
6330 @c only print the extra heading if both COFF and ELF are set
6331 @subheading COFF Version
6334 @cindex COFF symbol type
6335 @cindex symbol type, COFF
6336 @cindex @code{type} directive (COFF version)
6337 For COFF targets, this directive is permitted only within
6338 @code{.def}/@code{.endef} pairs. It is used like this:
6344 This records the integer @var{int} as the type attribute of a symbol table
6348 @samp{.type} is associated only with COFF format output; when
6349 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
6350 directive but ignores it.
6356 @c only print the extra heading if both COFF and ELF are set
6357 @subheading ELF Version
6360 @cindex ELF symbol type
6361 @cindex symbol type, ELF
6362 @cindex @code{type} directive (ELF version)
6363 For ELF targets, the @code{.type} directive is used like this:
6366 .type @var{name} , @var{type description}
6369 This sets the type of symbol @var{name} to be either a
6370 function symbol or an object symbol. There are five different syntaxes
6371 supported for the @var{type description} field, in order to provide
6372 compatibility with various other assemblers.
6374 Because some of the characters used in these syntaxes (such as @samp{@@} and
6375 @samp{#}) are comment characters for some architectures, some of the syntaxes
6376 below do not work on all architectures. The first variant will be accepted by
6377 the GNU assembler on all architectures so that variant should be used for
6378 maximum portability, if you do not need to assemble your code with other
6381 The syntaxes supported are:
6384 .type <name> STT_<TYPE_IN_UPPER_CASE>
6385 .type <name>,#<type>
6386 .type <name>,@@<type>
6387 .type <name>,%<type>
6388 .type <name>,"<type>"
6391 The types supported are:
6396 Mark the symbol as being a function name.
6399 @itemx gnu_indirect_function
6400 Mark the symbol as an indirect function when evaluated during reloc
6401 processing. (This is only supported on Linux targeted assemblers).
6405 Mark the symbol as being a data object.
6409 Mark the symbol as being a thead-local data object.
6413 Mark the symbol as being a common data object.
6417 Does not mark the symbol in any way. It is supported just for completeness.
6419 @item gnu_unique_object
6420 Marks the symbol as being a globally unique data object. The dynamic linker
6421 will make sure that in the entire process there is just one symbol with this
6422 name and type in use. (This is only supported on Linux targeted assemblers).
6426 Note: Some targets support extra types in addition to those listed above.
6432 @section @code{.uleb128 @var{expressions}}
6434 @cindex @code{uleb128} directive
6435 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
6436 compact, variable length representation of numbers used by the DWARF
6437 symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}.
6441 @section @code{.val @var{addr}}
6443 @cindex @code{val} directive
6444 @cindex COFF value attribute
6445 @cindex value attribute, COFF
6446 This directive, permitted only within @code{.def}/@code{.endef} pairs,
6447 records the address @var{addr} as the value attribute of a symbol table
6451 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
6452 configured for @code{b.out}, it accepts this directive but ignores it.
6458 @section @code{.version "@var{string}"}
6460 @cindex @code{version} directive
6461 This directive creates a @code{.note} section and places into it an ELF
6462 formatted note of type NT_VERSION. The note's name is set to @code{string}.
6467 @section @code{.vtable_entry @var{table}, @var{offset}}
6469 @cindex @code{vtable_entry} directive
6470 This directive finds or creates a symbol @code{table} and creates a
6471 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
6474 @section @code{.vtable_inherit @var{child}, @var{parent}}
6476 @cindex @code{vtable_inherit} directive
6477 This directive finds the symbol @code{child} and finds or creates the symbol
6478 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
6479 parent whose addend is the value of the child symbol. As a special case the
6480 parent name of @code{0} is treated as referring to the @code{*ABS*} section.
6484 @section @code{.warning "@var{string}"}
6485 @cindex warning directive
6486 Similar to the directive @code{.error}
6487 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
6490 @section @code{.weak @var{names}}
6492 @cindex @code{weak} directive
6493 This directive sets the weak attribute on the comma separated list of symbol
6494 @code{names}. If the symbols do not already exist, they will be created.
6496 On COFF targets other than PE, weak symbols are a GNU extension. This
6497 directive sets the weak attribute on the comma separated list of symbol
6498 @code{names}. If the symbols do not already exist, they will be created.
6500 On the PE target, weak symbols are supported natively as weak aliases.
6501 When a weak symbol is created that is not an alias, GAS creates an
6502 alternate symbol to hold the default value.
6505 @section @code{.weakref @var{alias}, @var{target}}
6507 @cindex @code{weakref} directive
6508 This directive creates an alias to the target symbol that enables the symbol to
6509 be referenced with weak-symbol semantics, but without actually making it weak.
6510 If direct references or definitions of the symbol are present, then the symbol
6511 will not be weak, but if all references to it are through weak references, the
6512 symbol will be marked as weak in the symbol table.
6514 The effect is equivalent to moving all references to the alias to a separate
6515 assembly source file, renaming the alias to the symbol in it, declaring the
6516 symbol as weak there, and running a reloadable link to merge the object files
6517 resulting from the assembly of the new source file and the old source file that
6518 had the references to the alias removed.
6520 The alias itself never makes to the symbol table, and is entirely handled
6521 within the assembler.
6524 @section @code{.word @var{expressions}}
6526 @cindex @code{word} directive
6527 This directive expects zero or more @var{expressions}, of any section,
6528 separated by commas.
6531 For each expression, @command{@value{AS}} emits a 32-bit number.
6534 For each expression, @command{@value{AS}} emits a 16-bit number.
6539 The size of the number emitted, and its byte order,
6540 depend on what target computer the assembly is for.
6543 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
6544 @c happen---32-bit addressability, period; no long/short jumps.
6545 @ifset DIFF-TBL-KLUGE
6546 @cindex difference tables altered
6547 @cindex altered difference tables
6549 @emph{Warning: Special Treatment to support Compilers}
6553 Machines with a 32-bit address space, but that do less than 32-bit
6554 addressing, require the following special treatment. If the machine of
6555 interest to you does 32-bit addressing (or doesn't require it;
6556 @pxref{Machine Dependencies}), you can ignore this issue.
6559 In order to assemble compiler output into something that works,
6560 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
6561 Directives of the form @samp{.word sym1-sym2} are often emitted by
6562 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
6563 directive of the form @samp{.word sym1-sym2}, and the difference between
6564 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
6565 creates a @dfn{secondary jump table}, immediately before the next label.
6566 This secondary jump table is preceded by a short-jump to the
6567 first byte after the secondary table. This short-jump prevents the flow
6568 of control from accidentally falling into the new table. Inside the
6569 table is a long-jump to @code{sym2}. The original @samp{.word}
6570 contains @code{sym1} minus the address of the long-jump to
6573 If there were several occurrences of @samp{.word sym1-sym2} before the
6574 secondary jump table, all of them are adjusted. If there was a
6575 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
6576 long-jump to @code{sym4} is included in the secondary jump table,
6577 and the @code{.word} directives are adjusted to contain @code{sym3}
6578 minus the address of the long-jump to @code{sym4}; and so on, for as many
6579 entries in the original jump table as necessary.
6582 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
6583 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
6584 assembly language programmers.
6587 @c end DIFF-TBL-KLUGE
6590 @section Deprecated Directives
6592 @cindex deprecated directives
6593 @cindex obsolescent directives
6594 One day these directives won't work.
6595 They are included for compatibility with older assemblers.
6602 @node Object Attributes
6603 @chapter Object Attributes
6604 @cindex object attributes
6606 @command{@value{AS}} assembles source files written for a specific architecture
6607 into object files for that architecture. But not all object files are alike.
6608 Many architectures support incompatible variations. For instance, floating
6609 point arguments might be passed in floating point registers if the object file
6610 requires hardware floating point support---or floating point arguments might be
6611 passed in integer registers if the object file supports processors with no
6612 hardware floating point unit. Or, if two objects are built for different
6613 generations of the same architecture, the combination may require the
6614 newer generation at run-time.
6616 This information is useful during and after linking. At link time,
6617 @command{@value{LD}} can warn about incompatible object files. After link
6618 time, tools like @command{gdb} can use it to process the linked file
6621 Compatibility information is recorded as a series of object attributes. Each
6622 attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
6623 string, and indicates who sets the meaning of the tag. The tag is an integer,
6624 and indicates what property the attribute describes. The value may be a string
6625 or an integer, and indicates how the property affects this object. Missing
6626 attributes are the same as attributes with a zero value or empty string value.
6628 Object attributes were developed as part of the ABI for the ARM Architecture.
6629 The file format is documented in @cite{ELF for the ARM Architecture}.
6632 * GNU Object Attributes:: @sc{gnu} Object Attributes
6633 * Defining New Object Attributes:: Defining New Object Attributes
6636 @node GNU Object Attributes
6637 @section @sc{gnu} Object Attributes
6639 The @code{.gnu_attribute} directive records an object attribute
6640 with vendor @samp{gnu}.
6642 Except for @samp{Tag_compatibility}, which has both an integer and a string for
6643 its value, @sc{gnu} attributes have a string value if the tag number is odd and
6644 an integer value if the tag number is even. The second bit (@code{@var{tag} &
6645 2} is set for architecture-independent attributes and clear for
6646 architecture-dependent ones.
6648 @subsection Common @sc{gnu} attributes
6650 These attributes are valid on all architectures.
6653 @item Tag_compatibility (32)
6654 The compatibility attribute takes an integer flag value and a vendor name. If
6655 the flag value is 0, the file is compatible with other toolchains. If it is 1,
6656 then the file is only compatible with the named toolchain. If it is greater
6657 than 1, the file can only be processed by other toolchains under some private
6658 arrangement indicated by the flag value and the vendor name.
6661 @subsection MIPS Attributes
6664 @item Tag_GNU_MIPS_ABI_FP (4)
6665 The floating-point ABI used by this object file. The value will be:
6669 0 for files not affected by the floating-point ABI.
6671 1 for files using the hardware floating-point with a standard double-precision
6674 2 for files using the hardware floating-point ABI with a single-precision FPU.
6676 3 for files using the software floating-point ABI.
6678 4 for files using the hardware floating-point ABI with 64-bit wide
6679 double-precision floating-point registers and 32-bit wide general
6684 @subsection PowerPC Attributes
6687 @item Tag_GNU_Power_ABI_FP (4)
6688 The floating-point ABI used by this object file. The value will be:
6692 0 for files not affected by the floating-point ABI.
6694 1 for files using double-precision hardware floating-point ABI.
6696 2 for files using the software floating-point ABI.
6698 3 for files using single-precision hardware floating-point ABI.
6701 @item Tag_GNU_Power_ABI_Vector (8)
6702 The vector ABI used by this object file. The value will be:
6706 0 for files not affected by the vector ABI.
6708 1 for files using general purpose registers to pass vectors.
6710 2 for files using AltiVec registers to pass vectors.
6712 3 for files using SPE registers to pass vectors.
6716 @node Defining New Object Attributes
6717 @section Defining New Object Attributes
6719 If you want to define a new @sc{gnu} object attribute, here are the places you
6720 will need to modify. New attributes should be discussed on the @samp{binutils}
6725 This manual, which is the official register of attributes.
6727 The header for your architecture @file{include/elf}, to define the tag.
6729 The @file{bfd} support file for your architecture, to merge the attribute
6730 and issue any appropriate link warnings.
6732 Test cases in @file{ld/testsuite} for merging and link warnings.
6734 @file{binutils/readelf.c} to display your attribute.
6736 GCC, if you want the compiler to mark the attribute automatically.
6742 @node Machine Dependencies
6743 @chapter Machine Dependent Features
6745 @cindex machine dependencies
6746 The machine instruction sets are (almost by definition) different on
6747 each machine where @command{@value{AS}} runs. Floating point representations
6748 vary as well, and @command{@value{AS}} often supports a few additional
6749 directives or command-line options for compatibility with other
6750 assemblers on a particular platform. Finally, some versions of
6751 @command{@value{AS}} support special pseudo-instructions for branch
6754 This chapter discusses most of these differences, though it does not
6755 include details on any machine's instruction set. For details on that
6756 subject, see the hardware manufacturer's manual.
6760 * Alpha-Dependent:: Alpha Dependent Features
6763 * ARC-Dependent:: ARC Dependent Features
6766 * ARM-Dependent:: ARM Dependent Features
6769 * AVR-Dependent:: AVR Dependent Features
6772 * Blackfin-Dependent:: Blackfin Dependent Features
6775 * CR16-Dependent:: CR16 Dependent Features
6778 * CRIS-Dependent:: CRIS Dependent Features
6781 * D10V-Dependent:: D10V Dependent Features
6784 * D30V-Dependent:: D30V Dependent Features
6787 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6790 * HPPA-Dependent:: HPPA Dependent Features
6793 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
6796 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
6799 * i860-Dependent:: Intel 80860 Dependent Features
6802 * i960-Dependent:: Intel 80960 Dependent Features
6805 * IA-64-Dependent:: Intel IA-64 Dependent Features
6808 * IP2K-Dependent:: IP2K Dependent Features
6811 * LM32-Dependent:: LM32 Dependent Features
6814 * M32C-Dependent:: M32C Dependent Features
6817 * M32R-Dependent:: M32R Dependent Features
6820 * M68K-Dependent:: M680x0 Dependent Features
6823 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
6826 * MicroBlaze-Dependent:: MICROBLAZE Dependent Features
6829 * MIPS-Dependent:: MIPS Dependent Features
6832 * MMIX-Dependent:: MMIX Dependent Features
6835 * MSP430-Dependent:: MSP430 Dependent Features
6838 * SH-Dependent:: Renesas / SuperH SH Dependent Features
6839 * SH64-Dependent:: SuperH SH64 Dependent Features
6842 * PDP-11-Dependent:: PDP-11 Dependent Features
6845 * PJ-Dependent:: picoJava Dependent Features
6848 * PPC-Dependent:: PowerPC Dependent Features
6851 * RX-Dependent:: RX Dependent Features
6854 * S/390-Dependent:: IBM S/390 Dependent Features
6857 * SCORE-Dependent:: SCORE Dependent Features
6860 * Sparc-Dependent:: SPARC Dependent Features
6863 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
6866 * V850-Dependent:: V850 Dependent Features
6869 * Xtensa-Dependent:: Xtensa Dependent Features
6872 * Z80-Dependent:: Z80 Dependent Features
6875 * Z8000-Dependent:: Z8000 Dependent Features
6878 * Vax-Dependent:: VAX Dependent Features
6885 @c The following major nodes are *sections* in the GENERIC version, *chapters*
6886 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
6887 @c peculiarity: to preserve cross-references, there must be a node called
6888 @c "Machine Dependencies". Hence the conditional nodenames in each
6889 @c major node below. Node defaulting in makeinfo requires adjacency of
6890 @c node and sectioning commands; hence the repetition of @chapter BLAH
6891 @c in both conditional blocks.
6894 @include c-alpha.texi
6910 @include c-bfin.texi
6914 @include c-cr16.texi
6918 @include c-cris.texi
6923 @node Machine Dependencies
6924 @chapter Machine Dependent Features
6926 The machine instruction sets are different on each Renesas chip family,
6927 and there are also some syntax differences among the families. This
6928 chapter describes the specific @command{@value{AS}} features for each
6932 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6933 * SH-Dependent:: Renesas SH Dependent Features
6940 @include c-d10v.texi
6944 @include c-d30v.texi
6948 @include c-h8300.texi
6952 @include c-hppa.texi
6956 @include c-i370.texi
6960 @include c-i386.texi
6964 @include c-i860.texi
6968 @include c-i960.texi
6972 @include c-ia64.texi
6976 @include c-ip2k.texi
6980 @include c-lm32.texi
6984 @include c-m32c.texi
6988 @include c-m32r.texi
6992 @include c-m68k.texi
6996 @include c-m68hc11.texi
7000 @include c-microblaze.texi
7004 @include c-mips.texi
7008 @include c-mmix.texi
7012 @include c-msp430.texi
7016 @include c-ns32k.texi
7020 @include c-pdp11.texi
7036 @include c-s390.texi
7040 @include c-score.texi
7045 @include c-sh64.texi
7049 @include c-sparc.texi
7053 @include c-tic54x.texi
7069 @include c-v850.texi
7073 @include c-xtensa.texi
7077 @c reverse effect of @down at top of generic Machine-Dep chapter
7081 @node Reporting Bugs
7082 @chapter Reporting Bugs
7083 @cindex bugs in assembler
7084 @cindex reporting bugs in assembler
7086 Your bug reports play an essential role in making @command{@value{AS}} reliable.
7088 Reporting a bug may help you by bringing a solution to your problem, or it may
7089 not. But in any case the principal function of a bug report is to help the
7090 entire community by making the next version of @command{@value{AS}} work better.
7091 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
7093 In order for a bug report to serve its purpose, you must include the
7094 information that enables us to fix the bug.
7097 * Bug Criteria:: Have you found a bug?
7098 * Bug Reporting:: How to report bugs
7102 @section Have You Found a Bug?
7103 @cindex bug criteria
7105 If you are not sure whether you have found a bug, here are some guidelines:
7108 @cindex fatal signal
7109 @cindex assembler crash
7110 @cindex crash of assembler
7112 If the assembler gets a fatal signal, for any input whatever, that is a
7113 @command{@value{AS}} bug. Reliable assemblers never crash.
7115 @cindex error on valid input
7117 If @command{@value{AS}} produces an error message for valid input, that is a bug.
7119 @cindex invalid input
7121 If @command{@value{AS}} does not produce an error message for invalid input, that
7122 is a bug. However, you should note that your idea of ``invalid input'' might
7123 be our idea of ``an extension'' or ``support for traditional practice''.
7126 If you are an experienced user of assemblers, your suggestions for improvement
7127 of @command{@value{AS}} are welcome in any case.
7131 @section How to Report Bugs
7133 @cindex assembler bugs, reporting
7135 A number of companies and individuals offer support for @sc{gnu} products. If
7136 you obtained @command{@value{AS}} from a support organization, we recommend you
7137 contact that organization first.
7139 You can find contact information for many support companies and
7140 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
7144 In any event, we also recommend that you send bug reports for @command{@value{AS}}
7148 The fundamental principle of reporting bugs usefully is this:
7149 @strong{report all the facts}. If you are not sure whether to state a
7150 fact or leave it out, state it!
7152 Often people omit facts because they think they know what causes the problem
7153 and assume that some details do not matter. Thus, you might assume that the
7154 name of a symbol you use in an example does not matter. Well, probably it does
7155 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
7156 happens to fetch from the location where that name is stored in memory;
7157 perhaps, if the name were different, the contents of that location would fool
7158 the assembler into doing the right thing despite the bug. Play it safe and
7159 give a specific, complete example. That is the easiest thing for you to do,
7160 and the most helpful.
7162 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
7163 it is new to us. Therefore, always write your bug reports on the assumption
7164 that the bug has not been reported previously.
7166 Sometimes people give a few sketchy facts and ask, ``Does this ring a
7167 bell?'' This cannot help us fix a bug, so it is basically useless. We
7168 respond by asking for enough details to enable us to investigate.
7169 You might as well expedite matters by sending them to begin with.
7171 To enable us to fix the bug, you should include all these things:
7175 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
7176 it with the @samp{--version} argument.
7178 Without this, we will not know whether there is any point in looking for
7179 the bug in the current version of @command{@value{AS}}.
7182 Any patches you may have applied to the @command{@value{AS}} source.
7185 The type of machine you are using, and the operating system name and
7189 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
7193 The command arguments you gave the assembler to assemble your example and
7194 observe the bug. To guarantee you will not omit something important, list them
7195 all. A copy of the Makefile (or the output from make) is sufficient.
7197 If we were to try to guess the arguments, we would probably guess wrong
7198 and then we might not encounter the bug.
7201 A complete input file that will reproduce the bug. If the bug is observed when
7202 the assembler is invoked via a compiler, send the assembler source, not the
7203 high level language source. Most compilers will produce the assembler source
7204 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
7205 the options @samp{-v --save-temps}; this will save the assembler source in a
7206 file with an extension of @file{.s}, and also show you exactly how
7207 @command{@value{AS}} is being run.
7210 A description of what behavior you observe that you believe is
7211 incorrect. For example, ``It gets a fatal signal.''
7213 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
7214 will certainly notice it. But if the bug is incorrect output, we might not
7215 notice unless it is glaringly wrong. You might as well not give us a chance to
7218 Even if the problem you experience is a fatal signal, you should still say so
7219 explicitly. Suppose something strange is going on, such as, your copy of
7220 @command{@value{AS}} is out of sync, or you have encountered a bug in the C
7221 library on your system. (This has happened!) Your copy might crash and ours
7222 would not. If you told us to expect a crash, then when ours fails to crash, we
7223 would know that the bug was not happening for us. If you had not told us to
7224 expect a crash, then we would not be able to draw any conclusion from our
7228 If you wish to suggest changes to the @command{@value{AS}} source, send us context
7229 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
7230 option. Always send diffs from the old file to the new file. If you even
7231 discuss something in the @command{@value{AS}} source, refer to it by context, not
7234 The line numbers in our development sources will not match those in your
7235 sources. Your line numbers would convey no useful information to us.
7238 Here are some things that are not necessary:
7242 A description of the envelope of the bug.
7244 Often people who encounter a bug spend a lot of time investigating
7245 which changes to the input file will make the bug go away and which
7246 changes will not affect it.
7248 This is often time consuming and not very useful, because the way we
7249 will find the bug is by running a single example under the debugger
7250 with breakpoints, not by pure deduction from a series of examples.
7251 We recommend that you save your time for something else.
7253 Of course, if you can find a simpler example to report @emph{instead}
7254 of the original one, that is a convenience for us. Errors in the
7255 output will be easier to spot, running under the debugger will take
7256 less time, and so on.
7258 However, simplification is not vital; if you do not want to do this,
7259 report the bug anyway and send us the entire test case you used.
7262 A patch for the bug.
7264 A patch for the bug does help us if it is a good one. But do not omit
7265 the necessary information, such as the test case, on the assumption that
7266 a patch is all we need. We might see problems with your patch and decide
7267 to fix the problem another way, or we might not understand it at all.
7269 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
7270 construct an example that will make the program follow a certain path through
7271 the code. If you do not send us the example, we will not be able to construct
7272 one, so we will not be able to verify that the bug is fixed.
7274 And if we cannot understand what bug you are trying to fix, or why your
7275 patch should be an improvement, we will not install it. A test case will
7276 help us to understand.
7279 A guess about what the bug is or what it depends on.
7281 Such guesses are usually wrong. Even we cannot guess right about such
7282 things without first using the debugger to find the facts.
7285 @node Acknowledgements
7286 @chapter Acknowledgements
7288 If you have contributed to GAS and your name isn't listed here,
7289 it is not meant as a slight. We just don't know about it. Send mail to the
7290 maintainer, and we'll correct the situation. Currently
7292 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
7294 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
7297 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
7298 information and the 68k series machines, most of the preprocessing pass, and
7299 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
7301 K. Richard Pixley maintained GAS for a while, adding various enhancements and
7302 many bug fixes, including merging support for several processors, breaking GAS
7303 up to handle multiple object file format back ends (including heavy rewrite,
7304 testing, an integration of the coff and b.out back ends), adding configuration
7305 including heavy testing and verification of cross assemblers and file splits
7306 and renaming, converted GAS to strictly ANSI C including full prototypes, added
7307 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
7308 port (including considerable amounts of reverse engineering), a SPARC opcode
7309 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
7310 assertions and made them work, much other reorganization, cleanup, and lint.
7312 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
7313 in format-specific I/O modules.
7315 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
7316 has done much work with it since.
7318 The Intel 80386 machine description was written by Eliot Dresselhaus.
7320 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
7322 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
7323 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
7325 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
7326 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
7327 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
7328 support a.out format.
7330 Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
7331 tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
7332 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
7333 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
7336 John Gilmore built the AMD 29000 support, added @code{.include} support, and
7337 simplified the configuration of which versions accept which directives. He
7338 updated the 68k machine description so that Motorola's opcodes always produced
7339 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
7340 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
7341 cross-compilation support, and one bug in relaxation that took a week and
7342 required the proverbial one-bit fix.
7344 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
7345 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
7346 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
7347 PowerPC assembler, and made a few other minor patches.
7349 Steve Chamberlain made GAS able to generate listings.
7351 Hewlett-Packard contributed support for the HP9000/300.
7353 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
7354 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
7355 formats). This work was supported by both the Center for Software Science at
7356 the University of Utah and Cygnus Support.
7358 Support for ELF format files has been worked on by Mark Eichin of Cygnus
7359 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
7360 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
7361 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
7362 and some initial 64-bit support).
7364 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
7366 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
7367 support for openVMS/Alpha.
7369 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
7372 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
7373 Inc.@: added support for Xtensa processors.
7375 Several engineers at Cygnus Support have also provided many small bug fixes and
7376 configuration enhancements.
7378 Jon Beniston added support for the Lattice Mico32 architecture.
7380 Many others have contributed large or small bugfixes and enhancements. If
7381 you have contributed significant work and are not mentioned on this list, and
7382 want to be, let us know. Some of the history has been lost; we are not
7383 intentionally leaving anyone out.
7385 @node GNU Free Documentation License
7386 @appendix GNU Free Documentation License
7390 @unnumbered AS Index
projects / external / binutils.git / blob