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, 2010
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, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
107 2000, 2001, 2002, 2006, 2007, 2008, 2009, 2010 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, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
157 2000, 2001, 2002, 2006, 2007, 2008, 2009, 2010 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 TIC6X options:}
478 [@b{-march=@var{arch}}] [@b{-matomic}|@b{-mno-atomic}]
479 [@b{-mbig-endian}|@b{-mlittle-endian}]
484 @emph{Target Z80 options:}
485 [@b{-z80}] [@b{-r800}]
486 [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}]
487 [@b{ -ignore-unportable-instructions}] [@b{-Wnup}]
488 [@b{ -warn-undocumented-instructions}] [@b{-Wud}]
489 [@b{ -warn-unportable-instructions}] [@b{-Wup}]
490 [@b{ -forbid-undocumented-instructions}] [@b{-Fud}]
491 [@b{ -forbid-unportable-instructions}] [@b{-Fup}]
495 @c Z8000 has no machine-dependent assembler options
499 @emph{Target Xtensa options:}
500 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
501 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
502 [@b{--[no-]transform}]
503 [@b{--rename-section} @var{oldname}=@var{newname}]
511 @include at-file.texi
514 Turn on listings, in any of a variety of ways:
518 omit false conditionals
521 omit debugging directives
524 include general information, like @value{AS} version and options passed
527 include high-level source
533 include macro expansions
536 omit forms processing
542 set the name of the listing file
545 You may combine these options; for example, use @samp{-aln} for assembly
546 listing without forms processing. The @samp{=file} option, if used, must be
547 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
550 Begin in alternate macro mode.
552 @xref{Altmacro,,@code{.altmacro}}.
556 Ignored. This option is accepted for script compatibility with calls to
559 @item --debug-prefix-map @var{old}=@var{new}
560 When assembling files in directory @file{@var{old}}, record debugging
561 information describing them as in @file{@var{new}} instead.
563 @item --defsym @var{sym}=@var{value}
564 Define the symbol @var{sym} to be @var{value} before assembling the input file.
565 @var{value} must be an integer constant. As in C, a leading @samp{0x}
566 indicates a hexadecimal value, and a leading @samp{0} indicates an octal
567 value. The value of the symbol can be overridden inside a source file via the
568 use of a @code{.set} pseudo-op.
571 ``fast''---skip whitespace and comment preprocessing (assume source is
576 Generate debugging information for each assembler source line using whichever
577 debug format is preferred by the target. This currently means either STABS,
581 Generate stabs debugging information for each assembler line. This
582 may help debugging assembler code, if the debugger can handle it.
585 Generate stabs debugging information for each assembler line, with GNU
586 extensions that probably only gdb can handle, and that could make other
587 debuggers crash or refuse to read your program. This
588 may help debugging assembler code. Currently the only GNU extension is
589 the location of the current working directory at assembling time.
592 Generate DWARF2 debugging information for each assembler line. This
593 may help debugging assembler code, if the debugger can handle it. Note---this
594 option is only supported by some targets, not all of them.
597 Print a summary of the command line options and exit.
600 Print a summary of all target specific options and exit.
603 Add directory @var{dir} to the search list for @code{.include} directives.
606 Don't warn about signed overflow.
609 @ifclear DIFF-TBL-KLUGE
610 This option is accepted but has no effect on the @value{TARGET} family.
612 @ifset DIFF-TBL-KLUGE
613 Issue warnings when difference tables altered for long displacements.
618 Keep (in the symbol table) local symbols. These symbols start with
619 system-specific local label prefixes, typically @samp{.L} for ELF systems
620 or @samp{L} for traditional a.out systems.
625 @item --listing-lhs-width=@var{number}
626 Set the maximum width, in words, of the output data column for an assembler
627 listing to @var{number}.
629 @item --listing-lhs-width2=@var{number}
630 Set the maximum width, in words, of the output data column for continuation
631 lines in an assembler listing to @var{number}.
633 @item --listing-rhs-width=@var{number}
634 Set the maximum width of an input source line, as displayed in a listing, to
637 @item --listing-cont-lines=@var{number}
638 Set the maximum number of lines printed in a listing for a single line of input
641 @item -o @var{objfile}
642 Name the object-file output from @command{@value{AS}} @var{objfile}.
645 Fold the data section into the text section.
647 @kindex --hash-size=@var{number}
648 Set the default size of GAS's hash tables to a prime number close to
649 @var{number}. Increasing this value can reduce the length of time it takes the
650 assembler to perform its tasks, at the expense of increasing the assembler's
651 memory requirements. Similarly reducing this value can reduce the memory
652 requirements at the expense of speed.
654 @item --reduce-memory-overheads
655 This option reduces GAS's memory requirements, at the expense of making the
656 assembly processes slower. Currently this switch is a synonym for
657 @samp{--hash-size=4051}, but in the future it may have other effects as well.
660 Print the maximum space (in bytes) and total time (in seconds) used by
663 @item --strip-local-absolute
664 Remove local absolute symbols from the outgoing symbol table.
668 Print the @command{as} version.
671 Print the @command{as} version and exit.
675 Suppress warning messages.
677 @item --fatal-warnings
678 Treat warnings as errors.
681 Don't suppress warning messages or treat them as errors.
690 Generate an object file even after errors.
692 @item -- | @var{files} @dots{}
693 Standard input, or source files to assemble.
698 The following options are available when @value{AS} is configured for
703 This option selects the core processor variant.
705 Select either big-endian (-EB) or little-endian (-EL) output.
710 The following options are available when @value{AS} is configured for the ARM
714 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
715 Specify which ARM processor variant is the target.
716 @item -march=@var{architecture}[+@var{extension}@dots{}]
717 Specify which ARM architecture variant is used by the target.
718 @item -mfpu=@var{floating-point-format}
719 Select which Floating Point architecture is the target.
720 @item -mfloat-abi=@var{abi}
721 Select which floating point ABI is in use.
723 Enable Thumb only instruction decoding.
724 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
725 Select which procedure calling convention is in use.
727 Select either big-endian (-EB) or little-endian (-EL) output.
728 @item -mthumb-interwork
729 Specify that the code has been generated with interworking between Thumb and
732 Specify that PIC code has been generated.
737 The following options are available when @value{AS} is configured for
738 the Blackfin processor family.
741 @item -mcpu=@var{processor}@r{[}-@var{sirevision}@r{]}
742 This option specifies the target processor. The optional @var{sirevision}
743 is not used in assembler.
745 Assemble for the FDPIC ABI.
753 See the info pages for documentation of the CRIS-specific options.
757 The following options are available when @value{AS} is configured for
760 @cindex D10V optimization
761 @cindex optimization, D10V
763 Optimize output by parallelizing instructions.
768 The following options are available when @value{AS} is configured for a D30V
771 @cindex D30V optimization
772 @cindex optimization, D30V
774 Optimize output by parallelizing instructions.
778 Warn when nops are generated.
780 @cindex D30V nops after 32-bit multiply
782 Warn when a nop after a 32-bit multiply instruction is generated.
787 The following options are available when @value{AS} is configured for the
788 Intel 80960 processor.
791 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
792 Specify which variant of the 960 architecture is the target.
795 Add code to collect statistics about branches taken.
798 Do not alter compare-and-branch instructions for long displacements;
805 The following options are available when @value{AS} is configured for the
811 Specifies that the extended IP2022 instructions are allowed.
814 Restores the default behaviour, which restricts the permitted instructions to
815 just the basic IP2022 ones.
821 The following options are available when @value{AS} is configured for the
822 Renesas M32C and M16C processors.
827 Assemble M32C instructions.
830 Assemble M16C instructions (the default).
833 Enable support for link-time relaxations.
836 Support H'00 style hex constants in addition to 0x00 style.
842 The following options are available when @value{AS} is configured for the
843 Renesas M32R (formerly Mitsubishi M32R) series.
848 Specify which processor in the M32R family is the target. The default
849 is normally the M32R, but this option changes it to the M32RX.
851 @item --warn-explicit-parallel-conflicts or --Wp
852 Produce warning messages when questionable parallel constructs are
855 @item --no-warn-explicit-parallel-conflicts or --Wnp
856 Do not produce warning messages when questionable parallel constructs are
863 The following options are available when @value{AS} is configured for the
864 Motorola 68000 series.
869 Shorten references to undefined symbols, to one word instead of two.
871 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
872 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
873 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
874 Specify what processor in the 68000 family is the target. The default
875 is normally the 68020, but this can be changed at configuration time.
877 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
878 The target machine does (or does not) have a floating-point coprocessor.
879 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
880 the basic 68000 is not compatible with the 68881, a combination of the
881 two can be specified, since it's possible to do emulation of the
882 coprocessor instructions with the main processor.
884 @item -m68851 | -mno-68851
885 The target machine does (or does not) have a memory-management
886 unit coprocessor. The default is to assume an MMU for 68020 and up.
893 For details about the PDP-11 machine dependent features options,
894 see @ref{PDP-11-Options}.
897 @item -mpic | -mno-pic
898 Generate position-independent (or position-dependent) code. The
899 default is @option{-mpic}.
902 @itemx -mall-extensions
903 Enable all instruction set extensions. This is the default.
905 @item -mno-extensions
906 Disable all instruction set extensions.
908 @item -m@var{extension} | -mno-@var{extension}
909 Enable (or disable) a particular instruction set extension.
912 Enable the instruction set extensions supported by a particular CPU, and
913 disable all other extensions.
915 @item -m@var{machine}
916 Enable the instruction set extensions supported by a particular machine
917 model, and disable all other extensions.
923 The following options are available when @value{AS} is configured for
924 a picoJava processor.
928 @cindex PJ endianness
929 @cindex endianness, PJ
930 @cindex big endian output, PJ
932 Generate ``big endian'' format output.
934 @cindex little endian output, PJ
936 Generate ``little endian'' format output.
942 The following options are available when @value{AS} is configured for the
943 Motorola 68HC11 or 68HC12 series.
947 @item -m68hc11 | -m68hc12 | -m68hcs12
948 Specify what processor is the target. The default is
949 defined by the configuration option when building the assembler.
952 Specify to use the 16-bit integer ABI.
955 Specify to use the 32-bit integer ABI.
958 Specify to use the 32-bit double ABI.
961 Specify to use the 64-bit double ABI.
963 @item --force-long-branches
964 Relative branches are turned into absolute ones. This concerns
965 conditional branches, unconditional branches and branches to a
968 @item -S | --short-branches
969 Do not turn relative branches into absolute ones
970 when the offset is out of range.
972 @item --strict-direct-mode
973 Do not turn the direct addressing mode into extended addressing mode
974 when the instruction does not support direct addressing mode.
976 @item --print-insn-syntax
977 Print the syntax of instruction in case of error.
979 @item --print-opcodes
980 print the list of instructions with syntax and then exit.
982 @item --generate-example
983 print an example of instruction for each possible instruction and then exit.
984 This option is only useful for testing @command{@value{AS}}.
990 The following options are available when @command{@value{AS}} is configured
991 for the SPARC architecture:
994 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
995 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
996 Explicitly select a variant of the SPARC architecture.
998 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
999 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
1001 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
1002 UltraSPARC extensions.
1004 @item -xarch=v8plus | -xarch=v8plusa
1005 For compatibility with the Solaris v9 assembler. These options are
1006 equivalent to -Av8plus and -Av8plusa, respectively.
1009 Warn when the assembler switches to another architecture.
1014 The following options are available when @value{AS} is configured for the 'c54x
1019 Enable extended addressing mode. All addresses and relocations will assume
1020 extended addressing (usually 23 bits).
1021 @item -mcpu=@var{CPU_VERSION}
1022 Sets the CPU version being compiled for.
1023 @item -merrors-to-file @var{FILENAME}
1024 Redirect error output to a file, for broken systems which don't support such
1025 behaviour in the shell.
1030 The following options are available when @value{AS} is configured for
1031 a @sc{mips} processor.
1035 This option sets the largest size of an object that can be referenced
1036 implicitly with the @code{gp} register. It is only accepted for targets that
1037 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
1039 @cindex MIPS endianness
1040 @cindex endianness, MIPS
1041 @cindex big endian output, MIPS
1043 Generate ``big endian'' format output.
1045 @cindex little endian output, MIPS
1047 Generate ``little endian'' format output.
1059 Generate code for a particular @sc{mips} Instruction Set Architecture level.
1060 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
1061 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
1062 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
1063 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and
1065 correspond to generic
1066 @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64},
1067 and @samp{MIPS64 Release 2}
1068 ISA processors, respectively.
1070 @item -march=@var{CPU}
1071 Generate code for a particular @sc{mips} cpu.
1073 @item -mtune=@var{cpu}
1074 Schedule and tune for a particular @sc{mips} cpu.
1078 Cause nops to be inserted if the read of the destination register
1079 of an mfhi or mflo instruction occurs in the following two instructions.
1083 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
1084 section instead of the standard ELF .stabs sections.
1088 Control generation of @code{.pdr} sections.
1092 The register sizes are normally inferred from the ISA and ABI, but these
1093 flags force a certain group of registers to be treated as 32 bits wide at
1094 all times. @samp{-mgp32} controls the size of general-purpose registers
1095 and @samp{-mfp32} controls the size of floating-point registers.
1099 Generate code for the MIPS 16 processor. This is equivalent to putting
1100 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
1101 turns off this option.
1104 @itemx -mno-smartmips
1105 Enables the SmartMIPS extension to the MIPS32 instruction set. This is
1106 equivalent to putting @code{.set smartmips} at the start of the assembly file.
1107 @samp{-mno-smartmips} turns off this option.
1111 Generate code for the MIPS-3D Application Specific Extension.
1112 This tells the assembler to accept MIPS-3D instructions.
1113 @samp{-no-mips3d} turns off this option.
1117 Generate code for the MDMX Application Specific Extension.
1118 This tells the assembler to accept MDMX instructions.
1119 @samp{-no-mdmx} turns off this option.
1123 Generate code for the DSP Release 1 Application Specific Extension.
1124 This tells the assembler to accept DSP Release 1 instructions.
1125 @samp{-mno-dsp} turns off this option.
1129 Generate code for the DSP Release 2 Application Specific Extension.
1130 This option implies -mdsp.
1131 This tells the assembler to accept DSP Release 2 instructions.
1132 @samp{-mno-dspr2} turns off this option.
1136 Generate code for the MT Application Specific Extension.
1137 This tells the assembler to accept MT instructions.
1138 @samp{-mno-mt} turns off this option.
1140 @item --construct-floats
1141 @itemx --no-construct-floats
1142 The @samp{--no-construct-floats} option disables the construction of
1143 double width floating point constants by loading the two halves of the
1144 value into the two single width floating point registers that make up
1145 the double width register. By default @samp{--construct-floats} is
1146 selected, allowing construction of these floating point constants.
1149 @item --emulation=@var{name}
1150 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
1151 for some other target, in all respects, including output format (choosing
1152 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
1153 debugging information or store symbol table information, and default
1154 endianness. The available configuration names are: @samp{mipsecoff},
1155 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
1156 @samp{mipsbelf}. The first two do not alter the default endianness from that
1157 of the primary target for which the assembler was configured; the others change
1158 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
1159 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
1160 selection in any case.
1162 This option is currently supported only when the primary target
1163 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
1164 Furthermore, the primary target or others specified with
1165 @samp{--enable-targets=@dots{}} at configuration time must include support for
1166 the other format, if both are to be available. For example, the Irix 5
1167 configuration includes support for both.
1169 Eventually, this option will support more configurations, with more
1170 fine-grained control over the assembler's behavior, and will be supported for
1174 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1181 Control how to deal with multiplication overflow and division by zero.
1182 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1183 (and only work for Instruction Set Architecture level 2 and higher);
1184 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1188 When this option is used, @command{@value{AS}} will issue a warning every
1189 time it generates a nop instruction from a macro.
1194 The following options are available when @value{AS} is configured for
1200 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1201 The command line option @samp{-nojsri2bsr} can be used to disable it.
1205 Enable or disable the silicon filter behaviour. By default this is disabled.
1206 The default can be overridden by the @samp{-sifilter} command line option.
1209 Alter jump instructions for long displacements.
1211 @item -mcpu=[210|340]
1212 Select the cpu type on the target hardware. This controls which instructions
1216 Assemble for a big endian target.
1219 Assemble for a little endian target.
1225 See the info pages for documentation of the MMIX-specific options.
1229 See the info pages for documentation of the RX-specific options.
1233 The following options are available when @value{AS} is configured for the s390
1239 Select the word size, either 31/32 bits or 64 bits.
1242 Select the architecture mode, either the Enterprise System
1243 Architecture (esa) or the z/Architecture mode (zarch).
1244 @item -march=@var{processor}
1245 Specify which s390 processor variant is the target, @samp{g6}, @samp{g6},
1246 @samp{z900}, @samp{z990}, @samp{z9-109}, @samp{z9-ec}, or @samp{z10}.
1248 @itemx -mno-regnames
1249 Allow or disallow symbolic names for registers.
1250 @item -mwarn-areg-zero
1251 Warn whenever the operand for a base or index register has been specified
1252 but evaluates to zero.
1257 The following options are available when @value{AS} is configured for a
1258 TMS320C6000 processor.
1261 @item -march=@var{arch}
1262 Enable (only) instructions from architecture @var{arch}. By default,
1263 all instructions are permitted.
1265 The following values of @var{arch} are accepted: @code{c62x},
1266 @code{c64x}, @code{c64x+}, @code{c67x}, @code{c67x+}, @code{c674x}.
1270 Enable or disable the optional C64x+ atomic operation instructions.
1271 By default, they are enabled if no @option{-march} option is given, or
1272 if an architecture is specified with @option{-march} that implies
1273 these instructions are present (currently, there are no such
1274 architectures); they are disabled if an architecture is specified with
1275 @option{-march} on which the instructions are optional or not
1276 present. This option overrides such a default from the architecture,
1277 independent of the order in which the @option{-march} or
1278 @option{-matomic} or @option{-mno-atomic} options are passed.
1281 @itemx -mlittle-endian
1282 Generate code for the specified endianness. The default is
1289 The following options are available when @value{AS} is configured for
1290 an Xtensa processor.
1293 @item --text-section-literals | --no-text-section-literals
1294 With @option{--text-@-section-@-literals}, literal pools are interspersed
1295 in the text section. The default is
1296 @option{--no-@-text-@-section-@-literals}, which places literals in a
1297 separate section in the output file. These options only affect literals
1298 referenced via PC-relative @code{L32R} instructions; literals for
1299 absolute mode @code{L32R} instructions are handled separately.
1301 @item --absolute-literals | --no-absolute-literals
1302 Indicate to the assembler whether @code{L32R} instructions use absolute
1303 or PC-relative addressing. The default is to assume absolute addressing
1304 if the Xtensa processor includes the absolute @code{L32R} addressing
1305 option. Otherwise, only the PC-relative @code{L32R} mode can be used.
1307 @item --target-align | --no-target-align
1308 Enable or disable automatic alignment to reduce branch penalties at the
1309 expense of some code density. The default is @option{--target-@-align}.
1311 @item --longcalls | --no-longcalls
1312 Enable or disable transformation of call instructions to allow calls
1313 across a greater range of addresses. The default is
1314 @option{--no-@-longcalls}.
1316 @item --transform | --no-transform
1317 Enable or disable all assembler transformations of Xtensa instructions.
1318 The default is @option{--transform};
1319 @option{--no-transform} should be used only in the rare cases when the
1320 instructions must be exactly as specified in the assembly source.
1322 @item --rename-section @var{oldname}=@var{newname}
1323 When generating output sections, rename the @var{oldname} section to
1329 The following options are available when @value{AS} is configured for
1330 a Z80 family processor.
1333 Assemble for Z80 processor.
1335 Assemble for R800 processor.
1336 @item -ignore-undocumented-instructions
1338 Assemble undocumented Z80 instructions that also work on R800 without warning.
1339 @item -ignore-unportable-instructions
1341 Assemble all undocumented Z80 instructions without warning.
1342 @item -warn-undocumented-instructions
1344 Issue a warning for undocumented Z80 instructions that also work on R800.
1345 @item -warn-unportable-instructions
1347 Issue a warning for undocumented Z80 instructions that do not work on R800.
1348 @item -forbid-undocumented-instructions
1350 Treat all undocumented instructions as errors.
1351 @item -forbid-unportable-instructions
1353 Treat undocumented Z80 instructions that do not work on R800 as errors.
1360 * Manual:: Structure of this Manual
1361 * GNU Assembler:: The GNU Assembler
1362 * Object Formats:: Object File Formats
1363 * Command Line:: Command Line
1364 * Input Files:: Input Files
1365 * Object:: Output (Object) File
1366 * Errors:: Error and Warning Messages
1370 @section Structure of this Manual
1372 @cindex manual, structure and purpose
1373 This manual is intended to describe what you need to know to use
1374 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1375 notation for symbols, constants, and expressions; the directives that
1376 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1379 We also cover special features in the @value{TARGET}
1380 configuration of @command{@value{AS}}, including assembler directives.
1383 This manual also describes some of the machine-dependent features of
1384 various flavors of the assembler.
1387 @cindex machine instructions (not covered)
1388 On the other hand, this manual is @emph{not} intended as an introduction
1389 to programming in assembly language---let alone programming in general!
1390 In a similar vein, we make no attempt to introduce the machine
1391 architecture; we do @emph{not} describe the instruction set, standard
1392 mnemonics, registers or addressing modes that are standard to a
1393 particular architecture.
1395 You may want to consult the manufacturer's
1396 machine architecture manual for this information.
1400 For information on the H8/300 machine instruction set, see @cite{H8/300
1401 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1402 Programming Manual} (Renesas).
1405 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1406 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1407 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1408 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1411 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1415 @c I think this is premature---doc@cygnus.com, 17jan1991
1417 Throughout this manual, we assume that you are running @dfn{GNU},
1418 the portable operating system from the @dfn{Free Software
1419 Foundation, Inc.}. This restricts our attention to certain kinds of
1420 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1421 once this assumption is granted examples and definitions need less
1424 @command{@value{AS}} is part of a team of programs that turn a high-level
1425 human-readable series of instructions into a low-level
1426 computer-readable series of instructions. Different versions of
1427 @command{@value{AS}} are used for different kinds of computer.
1430 @c There used to be a section "Terminology" here, which defined
1431 @c "contents", "byte", "word", and "long". Defining "word" to any
1432 @c particular size is confusing when the .word directive may generate 16
1433 @c bits on one machine and 32 bits on another; in general, for the user
1434 @c version of this manual, none of these terms seem essential to define.
1435 @c They were used very little even in the former draft of the manual;
1436 @c this draft makes an effort to avoid them (except in names of
1440 @section The GNU Assembler
1442 @c man begin DESCRIPTION
1444 @sc{gnu} @command{as} is really a family of assemblers.
1446 This manual describes @command{@value{AS}}, a member of that family which is
1447 configured for the @value{TARGET} architectures.
1449 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1450 should find a fairly similar environment when you use it on another
1451 architecture. Each version has much in common with the others,
1452 including object file formats, most assembler directives (often called
1453 @dfn{pseudo-ops}) and assembler syntax.@refill
1455 @cindex purpose of @sc{gnu} assembler
1456 @command{@value{AS}} is primarily intended to assemble the output of the
1457 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1458 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1459 assemble correctly everything that other assemblers for the same
1460 machine would assemble.
1462 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1465 @c This remark should appear in generic version of manual; assumption
1466 @c here is that generic version sets M680x0.
1467 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1468 assembler for the same architecture; for example, we know of several
1469 incompatible versions of 680x0 assembly language syntax.
1474 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1475 program in one pass of the source file. This has a subtle impact on the
1476 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1478 @node Object Formats
1479 @section Object File Formats
1481 @cindex object file format
1482 The @sc{gnu} assembler can be configured to produce several alternative
1483 object file formats. For the most part, this does not affect how you
1484 write assembly language programs; but directives for debugging symbols
1485 are typically different in different file formats. @xref{Symbol
1486 Attributes,,Symbol Attributes}.
1489 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1490 @value{OBJ-NAME} format object files.
1492 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1494 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1495 @code{b.out} or COFF format object files.
1498 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1499 SOM or ELF format object files.
1504 @section Command Line
1506 @cindex command line conventions
1508 After the program name @command{@value{AS}}, the command line may contain
1509 options and file names. Options may appear in any order, and may be
1510 before, after, or between file names. The order of file names is
1513 @cindex standard input, as input file
1515 @file{--} (two hyphens) by itself names the standard input file
1516 explicitly, as one of the files for @command{@value{AS}} to assemble.
1518 @cindex options, command line
1519 Except for @samp{--} any command line argument that begins with a
1520 hyphen (@samp{-}) is an option. Each option changes the behavior of
1521 @command{@value{AS}}. No option changes the way another option works. An
1522 option is a @samp{-} followed by one or more letters; the case of
1523 the letter is important. All options are optional.
1525 Some options expect exactly one file name to follow them. The file
1526 name may either immediately follow the option's letter (compatible
1527 with older assemblers) or it may be the next command argument (@sc{gnu}
1528 standard). These two command lines are equivalent:
1531 @value{AS} -o my-object-file.o mumble.s
1532 @value{AS} -omy-object-file.o mumble.s
1536 @section Input Files
1539 @cindex source program
1540 @cindex files, input
1541 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1542 describe the program input to one run of @command{@value{AS}}. The program may
1543 be in one or more files; how the source is partitioned into files
1544 doesn't change the meaning of the source.
1546 @c I added "con" prefix to "catenation" just to prove I can overcome my
1547 @c APL training... doc@cygnus.com
1548 The source program is a concatenation of the text in all the files, in the
1551 @c man begin DESCRIPTION
1552 Each time you run @command{@value{AS}} it assembles exactly one source
1553 program. The source program is made up of one or more files.
1554 (The standard input is also a file.)
1556 You give @command{@value{AS}} a command line that has zero or more input file
1557 names. The input files are read (from left file name to right). A
1558 command line argument (in any position) that has no special meaning
1559 is taken to be an input file name.
1561 If you give @command{@value{AS}} no file names it attempts to read one input file
1562 from the @command{@value{AS}} standard input, which is normally your terminal. You
1563 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1566 Use @samp{--} if you need to explicitly name the standard input file
1567 in your command line.
1569 If the source is empty, @command{@value{AS}} produces a small, empty object
1574 @subheading Filenames and Line-numbers
1576 @cindex input file linenumbers
1577 @cindex line numbers, in input files
1578 There are two ways of locating a line in the input file (or files) and
1579 either may be used in reporting error messages. One way refers to a line
1580 number in a physical file; the other refers to a line number in a
1581 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1583 @dfn{Physical files} are those files named in the command line given
1584 to @command{@value{AS}}.
1586 @dfn{Logical files} are simply names declared explicitly by assembler
1587 directives; they bear no relation to physical files. Logical file names help
1588 error messages reflect the original source file, when @command{@value{AS}} source
1589 is itself synthesized from other files. @command{@value{AS}} understands the
1590 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1591 @ref{File,,@code{.file}}.
1594 @section Output (Object) File
1600 Every time you run @command{@value{AS}} it produces an output file, which is
1601 your assembly language program translated into numbers. This file
1602 is the object file. Its default name is
1610 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1612 You can give it another name by using the @option{-o} option. Conventionally,
1613 object file names end with @file{.o}. The default name is used for historical
1614 reasons: older assemblers were capable of assembling self-contained programs
1615 directly into a runnable program. (For some formats, this isn't currently
1616 possible, but it can be done for the @code{a.out} format.)
1620 The object file is meant for input to the linker @code{@value{LD}}. It contains
1621 assembled program code, information to help @code{@value{LD}} integrate
1622 the assembled program into a runnable file, and (optionally) symbolic
1623 information for the debugger.
1625 @c link above to some info file(s) like the description of a.out.
1626 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1629 @section Error and Warning Messages
1631 @c man begin DESCRIPTION
1633 @cindex error messages
1634 @cindex warning messages
1635 @cindex messages from assembler
1636 @command{@value{AS}} may write warnings and error messages to the standard error
1637 file (usually your terminal). This should not happen when a compiler
1638 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1639 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1640 grave problem that stops the assembly.
1644 @cindex format of warning messages
1645 Warning messages have the format
1648 file_name:@b{NNN}:Warning Message Text
1652 @cindex line numbers, in warnings/errors
1653 (where @b{NNN} is a line number). If a logical file name has been given
1654 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1655 the current input file is used. If a logical line number was given
1657 (@pxref{Line,,@code{.line}})
1659 then it is used to calculate the number printed,
1660 otherwise the actual line in the current source file is printed. The
1661 message text is intended to be self explanatory (in the grand Unix
1664 @cindex format of error messages
1665 Error messages have the format
1667 file_name:@b{NNN}:FATAL:Error Message Text
1669 The file name and line number are derived as for warning
1670 messages. The actual message text may be rather less explanatory
1671 because many of them aren't supposed to happen.
1674 @chapter Command-Line Options
1676 @cindex options, all versions of assembler
1677 This chapter describes command-line options available in @emph{all}
1678 versions of the @sc{gnu} assembler; see @ref{Machine Dependencies},
1679 for options specific
1681 to the @value{TARGET} target.
1684 to particular machine architectures.
1687 @c man begin DESCRIPTION
1689 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
1690 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1691 The assembler arguments must be separated from each other (and the @samp{-Wa})
1692 by commas. For example:
1695 gcc -c -g -O -Wa,-alh,-L file.c
1699 This passes two options to the assembler: @samp{-alh} (emit a listing to
1700 standard output with high-level and assembly source) and @samp{-L} (retain
1701 local symbols in the symbol table).
1703 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1704 command-line options are automatically passed to the assembler by the compiler.
1705 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1706 precisely what options it passes to each compilation pass, including the
1712 * a:: -a[cdghlns] enable listings
1713 * alternate:: --alternate enable alternate macro syntax
1714 * D:: -D for compatibility
1715 * f:: -f to work faster
1716 * I:: -I for .include search path
1717 @ifclear DIFF-TBL-KLUGE
1718 * K:: -K for compatibility
1720 @ifset DIFF-TBL-KLUGE
1721 * K:: -K for difference tables
1724 * L:: -L to retain local symbols
1725 * listing:: --listing-XXX to configure listing output
1726 * M:: -M or --mri to assemble in MRI compatibility mode
1727 * MD:: --MD for dependency tracking
1728 * o:: -o to name the object file
1729 * R:: -R to join data and text sections
1730 * statistics:: --statistics to see statistics about assembly
1731 * traditional-format:: --traditional-format for compatible output
1732 * v:: -v to announce version
1733 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1734 * Z:: -Z to make object file even after errors
1738 @section Enable Listings: @option{-a[cdghlns]}
1748 @cindex listings, enabling
1749 @cindex assembly listings, enabling
1751 These options enable listing output from the assembler. By itself,
1752 @samp{-a} requests high-level, assembly, and symbols listing.
1753 You can use other letters to select specific options for the list:
1754 @samp{-ah} requests a high-level language listing,
1755 @samp{-al} requests an output-program assembly listing, and
1756 @samp{-as} requests a symbol table listing.
1757 High-level listings require that a compiler debugging option like
1758 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1761 Use the @samp{-ag} option to print a first section with general assembly
1762 information, like @value{AS} version, switches passed, or time stamp.
1764 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1765 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1766 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1767 omitted from the listing.
1769 Use the @samp{-ad} option to omit debugging directives from the
1772 Once you have specified one of these options, you can further control
1773 listing output and its appearance using the directives @code{.list},
1774 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1776 The @samp{-an} option turns off all forms processing.
1777 If you do not request listing output with one of the @samp{-a} options, the
1778 listing-control directives have no effect.
1780 The letters after @samp{-a} may be combined into one option,
1781 @emph{e.g.}, @samp{-aln}.
1783 Note if the assembler source is coming from the standard input (e.g.,
1785 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1786 is being used) then the listing will not contain any comments or preprocessor
1787 directives. This is because the listing code buffers input source lines from
1788 stdin only after they have been preprocessed by the assembler. This reduces
1789 memory usage and makes the code more efficient.
1792 @section @option{--alternate}
1795 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
1798 @section @option{-D}
1801 This option has no effect whatsoever, but it is accepted to make it more
1802 likely that scripts written for other assemblers also work with
1803 @command{@value{AS}}.
1806 @section Work Faster: @option{-f}
1809 @cindex trusted compiler
1810 @cindex faster processing (@option{-f})
1811 @samp{-f} should only be used when assembling programs written by a
1812 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1813 and comment preprocessing on
1814 the input file(s) before assembling them. @xref{Preprocessing,
1818 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1819 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1824 @section @code{.include} Search Path: @option{-I} @var{path}
1826 @kindex -I @var{path}
1827 @cindex paths for @code{.include}
1828 @cindex search path for @code{.include}
1829 @cindex @code{include} directive search path
1830 Use this option to add a @var{path} to the list of directories
1831 @command{@value{AS}} searches for files specified in @code{.include}
1832 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1833 many times as necessary to include a variety of paths. The current
1834 working directory is always searched first; after that, @command{@value{AS}}
1835 searches any @samp{-I} directories in the same order as they were
1836 specified (left to right) on the command line.
1839 @section Difference Tables: @option{-K}
1842 @ifclear DIFF-TBL-KLUGE
1843 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1844 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1845 where it can be used to warn when the assembler alters the machine code
1846 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1847 family does not have the addressing limitations that sometimes lead to this
1848 alteration on other platforms.
1851 @ifset DIFF-TBL-KLUGE
1852 @cindex difference tables, warning
1853 @cindex warning for altered difference tables
1854 @command{@value{AS}} sometimes alters the code emitted for directives of the
1855 form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}.
1856 You can use the @samp{-K} option if you want a warning issued when this
1861 @section Include Local Symbols: @option{-L}
1864 @cindex local symbols, retaining in output
1865 Symbols beginning with system-specific local label prefixes, typically
1866 @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are
1867 called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see
1868 such symbols when debugging, because they are intended for the use of
1869 programs (like compilers) that compose assembler programs, not for your
1870 notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard
1871 such symbols, so you do not normally debug with them.
1873 This option tells @command{@value{AS}} to retain those local symbols
1874 in the object file. Usually if you do this you also tell the linker
1875 @code{@value{LD}} to preserve those symbols.
1878 @section Configuring listing output: @option{--listing}
1880 The listing feature of the assembler can be enabled via the command line switch
1881 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1882 hex dump of the corresponding locations in the output object file, and displays
1883 them as a listing file. The format of this listing can be controlled by
1884 directives inside the assembler source (i.e., @code{.list} (@pxref{List}),
1885 @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}),
1886 @code{.psize} (@pxref{Psize}), and
1887 @code{.eject} (@pxref{Eject}) and also by the following switches:
1890 @item --listing-lhs-width=@samp{number}
1891 @kindex --listing-lhs-width
1892 @cindex Width of first line disassembly output
1893 Sets the maximum width, in words, of the first line of the hex byte dump. This
1894 dump appears on the left hand side of the listing output.
1896 @item --listing-lhs-width2=@samp{number}
1897 @kindex --listing-lhs-width2
1898 @cindex Width of continuation lines of disassembly output
1899 Sets the maximum width, in words, of any further lines of the hex byte dump for
1900 a given input source line. If this value is not specified, it defaults to being
1901 the same as the value specified for @samp{--listing-lhs-width}. If neither
1902 switch is used the default is to one.
1904 @item --listing-rhs-width=@samp{number}
1905 @kindex --listing-rhs-width
1906 @cindex Width of source line output
1907 Sets the maximum width, in characters, of the source line that is displayed
1908 alongside the hex dump. The default value for this parameter is 100. The
1909 source line is displayed on the right hand side of the listing output.
1911 @item --listing-cont-lines=@samp{number}
1912 @kindex --listing-cont-lines
1913 @cindex Maximum number of continuation lines
1914 Sets the maximum number of continuation lines of hex dump that will be
1915 displayed for a given single line of source input. The default value is 4.
1919 @section Assemble in MRI Compatibility Mode: @option{-M}
1922 @cindex MRI compatibility mode
1923 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1924 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1925 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1926 configured target) assembler from Microtec Research. The exact nature of the
1927 MRI syntax will not be documented here; see the MRI manuals for more
1928 information. Note in particular that the handling of macros and macro
1929 arguments is somewhat different. The purpose of this option is to permit
1930 assembling existing MRI assembler code using @command{@value{AS}}.
1932 The MRI compatibility is not complete. Certain operations of the MRI assembler
1933 depend upon its object file format, and can not be supported using other object
1934 file formats. Supporting these would require enhancing each object file format
1935 individually. These are:
1938 @item global symbols in common section
1940 The m68k MRI assembler supports common sections which are merged by the linker.
1941 Other object file formats do not support this. @command{@value{AS}} handles
1942 common sections by treating them as a single common symbol. It permits local
1943 symbols to be defined within a common section, but it can not support global
1944 symbols, since it has no way to describe them.
1946 @item complex relocations
1948 The MRI assemblers support relocations against a negated section address, and
1949 relocations which combine the start addresses of two or more sections. These
1950 are not support by other object file formats.
1952 @item @code{END} pseudo-op specifying start address
1954 The MRI @code{END} pseudo-op permits the specification of a start address.
1955 This is not supported by other object file formats. The start address may
1956 instead be specified using the @option{-e} option to the linker, or in a linker
1959 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1961 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1962 name to the output file. This is not supported by other object file formats.
1964 @item @code{ORG} pseudo-op
1966 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1967 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1968 which changes the location within the current section. Absolute sections are
1969 not supported by other object file formats. The address of a section may be
1970 assigned within a linker script.
1973 There are some other features of the MRI assembler which are not supported by
1974 @command{@value{AS}}, typically either because they are difficult or because they
1975 seem of little consequence. Some of these may be supported in future releases.
1979 @item EBCDIC strings
1981 EBCDIC strings are not supported.
1983 @item packed binary coded decimal
1985 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1986 and @code{DCB.P} pseudo-ops are not supported.
1988 @item @code{FEQU} pseudo-op
1990 The m68k @code{FEQU} pseudo-op is not supported.
1992 @item @code{NOOBJ} pseudo-op
1994 The m68k @code{NOOBJ} pseudo-op is not supported.
1996 @item @code{OPT} branch control options
1998 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1999 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
2000 relaxes all branches, whether forward or backward, to an appropriate size, so
2001 these options serve no purpose.
2003 @item @code{OPT} list control options
2005 The following m68k @code{OPT} list control options are ignored: @code{C},
2006 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
2007 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
2009 @item other @code{OPT} options
2011 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
2012 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
2014 @item @code{OPT} @code{D} option is default
2016 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
2017 @code{OPT NOD} may be used to turn it off.
2019 @item @code{XREF} pseudo-op.
2021 The m68k @code{XREF} pseudo-op is ignored.
2023 @item @code{.debug} pseudo-op
2025 The i960 @code{.debug} pseudo-op is not supported.
2027 @item @code{.extended} pseudo-op
2029 The i960 @code{.extended} pseudo-op is not supported.
2031 @item @code{.list} pseudo-op.
2033 The various options of the i960 @code{.list} pseudo-op are not supported.
2035 @item @code{.optimize} pseudo-op
2037 The i960 @code{.optimize} pseudo-op is not supported.
2039 @item @code{.output} pseudo-op
2041 The i960 @code{.output} pseudo-op is not supported.
2043 @item @code{.setreal} pseudo-op
2045 The i960 @code{.setreal} pseudo-op is not supported.
2050 @section Dependency Tracking: @option{--MD}
2053 @cindex dependency tracking
2056 @command{@value{AS}} can generate a dependency file for the file it creates. This
2057 file consists of a single rule suitable for @code{make} describing the
2058 dependencies of the main source file.
2060 The rule is written to the file named in its argument.
2062 This feature is used in the automatic updating of makefiles.
2065 @section Name the Object File: @option{-o}
2068 @cindex naming object file
2069 @cindex object file name
2070 There is always one object file output when you run @command{@value{AS}}. By
2071 default it has the name
2074 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
2088 You use this option (which takes exactly one filename) to give the
2089 object file a different name.
2091 Whatever the object file is called, @command{@value{AS}} overwrites any
2092 existing file of the same name.
2095 @section Join Data and Text Sections: @option{-R}
2098 @cindex data and text sections, joining
2099 @cindex text and data sections, joining
2100 @cindex joining text and data sections
2101 @cindex merging text and data sections
2102 @option{-R} tells @command{@value{AS}} to write the object file as if all
2103 data-section data lives in the text section. This is only done at
2104 the very last moment: your binary data are the same, but data
2105 section parts are relocated differently. The data section part of
2106 your object file is zero bytes long because all its bytes are
2107 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
2109 When you specify @option{-R} it would be possible to generate shorter
2110 address displacements (because we do not have to cross between text and
2111 data section). We refrain from doing this simply for compatibility with
2112 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
2115 When @command{@value{AS}} is configured for COFF or ELF output,
2116 this option is only useful if you use sections named @samp{.text} and
2121 @option{-R} is not supported for any of the HPPA targets. Using
2122 @option{-R} generates a warning from @command{@value{AS}}.
2126 @section Display Assembly Statistics: @option{--statistics}
2128 @kindex --statistics
2129 @cindex statistics, about assembly
2130 @cindex time, total for assembly
2131 @cindex space used, maximum for assembly
2132 Use @samp{--statistics} to display two statistics about the resources used by
2133 @command{@value{AS}}: the maximum amount of space allocated during the assembly
2134 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
2137 @node traditional-format
2138 @section Compatible Output: @option{--traditional-format}
2140 @kindex --traditional-format
2141 For some targets, the output of @command{@value{AS}} is different in some ways
2142 from the output of some existing assembler. This switch requests
2143 @command{@value{AS}} to use the traditional format instead.
2145 For example, it disables the exception frame optimizations which
2146 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
2149 @section Announce Version: @option{-v}
2153 @cindex assembler version
2154 @cindex version of assembler
2155 You can find out what version of as is running by including the
2156 option @samp{-v} (which you can also spell as @samp{-version}) on the
2160 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
2162 @command{@value{AS}} should never give a warning or error message when
2163 assembling compiler output. But programs written by people often
2164 cause @command{@value{AS}} to give a warning that a particular assumption was
2165 made. All such warnings are directed to the standard error file.
2169 @cindex suppressing warnings
2170 @cindex warnings, suppressing
2171 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
2172 This only affects the warning messages: it does not change any particular of
2173 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
2176 @kindex --fatal-warnings
2177 @cindex errors, caused by warnings
2178 @cindex warnings, causing error
2179 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
2180 files that generate warnings to be in error.
2183 @cindex warnings, switching on
2184 You can switch these options off again by specifying @option{--warn}, which
2185 causes warnings to be output as usual.
2188 @section Generate Object File in Spite of Errors: @option{-Z}
2189 @cindex object file, after errors
2190 @cindex errors, continuing after
2191 After an error message, @command{@value{AS}} normally produces no output. If for
2192 some reason you are interested in object file output even after
2193 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
2194 option. If there are any errors, @command{@value{AS}} continues anyways, and
2195 writes an object file after a final warning message of the form @samp{@var{n}
2196 errors, @var{m} warnings, generating bad object file.}
2201 @cindex machine-independent syntax
2202 @cindex syntax, machine-independent
2203 This chapter describes the machine-independent syntax allowed in a
2204 source file. @command{@value{AS}} syntax is similar to what many other
2205 assemblers use; it is inspired by the BSD 4.2
2210 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
2214 * Preprocessing:: Preprocessing
2215 * Whitespace:: Whitespace
2216 * Comments:: Comments
2217 * Symbol Intro:: Symbols
2218 * Statements:: Statements
2219 * Constants:: Constants
2223 @section Preprocessing
2225 @cindex preprocessing
2226 The @command{@value{AS}} internal preprocessor:
2228 @cindex whitespace, removed by preprocessor
2230 adjusts and removes extra whitespace. It leaves one space or tab before
2231 the keywords on a line, and turns any other whitespace on the line into
2234 @cindex comments, removed by preprocessor
2236 removes all comments, replacing them with a single space, or an
2237 appropriate number of newlines.
2239 @cindex constants, converted by preprocessor
2241 converts character constants into the appropriate numeric values.
2244 It does not do macro processing, include file handling, or
2245 anything else you may get from your C compiler's preprocessor. You can
2246 do include file processing with the @code{.include} directive
2247 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2248 to get other ``CPP'' style preprocessing by giving the input file a
2249 @samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of
2250 Output, gcc.info, Using GNU CC}.
2252 Excess whitespace, comments, and character constants
2253 cannot be used in the portions of the input text that are not
2256 @cindex turning preprocessing on and off
2257 @cindex preprocessing, turning on and off
2260 If the first line of an input file is @code{#NO_APP} or if you use the
2261 @samp{-f} option, whitespace and comments are not removed from the input file.
2262 Within an input file, you can ask for whitespace and comment removal in
2263 specific portions of the by putting a line that says @code{#APP} before the
2264 text that may contain whitespace or comments, and putting a line that says
2265 @code{#NO_APP} after this text. This feature is mainly intend to support
2266 @code{asm} statements in compilers whose output is otherwise free of comments
2273 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2274 Whitespace is used to separate symbols, and to make programs neater for
2275 people to read. Unless within character constants
2276 (@pxref{Characters,,Character Constants}), any whitespace means the same
2277 as exactly one space.
2283 There are two ways of rendering comments to @command{@value{AS}}. In both
2284 cases the comment is equivalent to one space.
2286 Anything from @samp{/*} through the next @samp{*/} is a comment.
2287 This means you may not nest these comments.
2291 The only way to include a newline ('\n') in a comment
2292 is to use this sort of comment.
2295 /* This sort of comment does not nest. */
2298 @cindex line comment character
2299 Anything from the @dfn{line comment} character to the next newline
2300 is considered a comment and is ignored. The line comment character is
2302 @samp{;} on the ARC;
2305 @samp{@@} on the ARM;
2308 @samp{;} for the H8/300 family;
2311 @samp{;} for the HPPA;
2314 @samp{#} on the i386 and x86-64;
2317 @samp{#} on the i960;
2320 @samp{;} for the PDP-11;
2323 @samp{;} for picoJava;
2326 @samp{#} for Motorola PowerPC;
2329 @samp{#} for IBM S/390;
2332 @samp{#} for the Sunplus SCORE;
2335 @samp{!} for the Renesas / SuperH SH;
2338 @samp{!} on the SPARC;
2341 @samp{#} on the ip2k;
2344 @samp{#} on the m32c;
2347 @samp{#} on the m32r;
2350 @samp{|} on the 680x0;
2353 @samp{#} on the 68HC11 and 68HC12;
2359 @samp{;} on the TMS320C6X;
2362 @samp{#} on the Vax;
2365 @samp{;} for the Z80;
2368 @samp{!} for the Z8000;
2371 @samp{#} on the V850;
2374 @samp{#} for Xtensa systems;
2376 see @ref{Machine Dependencies}. @refill
2377 @c FIXME What about i860?
2380 On some machines there are two different line comment characters. One
2381 character only begins a comment if it is the first non-whitespace character on
2382 a line, while the other always begins a comment.
2386 The V850 assembler also supports a double dash as starting a comment that
2387 extends to the end of the line.
2393 @cindex lines starting with @code{#}
2394 @cindex logical line numbers
2395 To be compatible with past assemblers, lines that begin with @samp{#} have a
2396 special interpretation. Following the @samp{#} should be an absolute
2397 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2398 line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a
2399 new logical file name. The rest of the line, if any, should be whitespace.
2401 If the first non-whitespace characters on the line are not numeric,
2402 the line is ignored. (Just like a comment.)
2405 # This is an ordinary comment.
2406 # 42-6 "new_file_name" # New logical file name
2407 # This is logical line # 36.
2409 This feature is deprecated, and may disappear from future versions
2410 of @command{@value{AS}}.
2415 @cindex characters used in symbols
2416 @ifclear SPECIAL-SYMS
2417 A @dfn{symbol} is one or more characters chosen from the set of all
2418 letters (both upper and lower case), digits and the three characters
2424 A @dfn{symbol} is one or more characters chosen from the set of all
2425 letters (both upper and lower case), digits and the three characters
2426 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2432 On most machines, you can also use @code{$} in symbol names; exceptions
2433 are noted in @ref{Machine Dependencies}.
2435 No symbol may begin with a digit. Case is significant.
2436 There is no length limit: all characters are significant. Symbols are
2437 delimited by characters not in that set, or by the beginning of a file
2438 (since the source program must end with a newline, the end of a file is
2439 not a possible symbol delimiter). @xref{Symbols}.
2440 @cindex length of symbols
2445 @cindex statements, structure of
2446 @cindex line separator character
2447 @cindex statement separator character
2449 @ifclear abnormal-separator
2450 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2451 semicolon (@samp{;}). The newline or semicolon is considered part of
2452 the preceding statement. Newlines and semicolons within character
2453 constants are an exception: they do not end statements.
2455 @ifset abnormal-separator
2457 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2458 point (@samp{!}). The newline or exclamation point is considered part of the
2459 preceding statement. Newlines and exclamation points within character
2460 constants are an exception: they do not end statements.
2463 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2464 H8/300) a dollar sign (@samp{$}); or (for the Renesas-SH) a semicolon
2465 (@samp{;}). The newline or separator character is considered part of
2466 the preceding statement. Newlines and separators within character
2467 constants are an exception: they do not end statements.
2472 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2473 separator character. (The line separator is usually @samp{;}, unless this
2474 conflicts with the comment character; see @ref{Machine Dependencies}.) The
2475 newline or separator character is considered part of the preceding
2476 statement. Newlines and separators within character constants are an
2477 exception: they do not end statements.
2480 @cindex newline, required at file end
2481 @cindex EOF, newline must precede
2482 It is an error to end any statement with end-of-file: the last
2483 character of any input file should be a newline.@refill
2485 An empty statement is allowed, and may include whitespace. It is ignored.
2487 @cindex instructions and directives
2488 @cindex directives and instructions
2489 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2490 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2492 A statement begins with zero or more labels, optionally followed by a
2493 key symbol which determines what kind of statement it is. The key
2494 symbol determines the syntax of the rest of the statement. If the
2495 symbol begins with a dot @samp{.} then the statement is an assembler
2496 directive: typically valid for any computer. If the symbol begins with
2497 a letter the statement is an assembly language @dfn{instruction}: it
2498 assembles into a machine language instruction.
2500 Different versions of @command{@value{AS}} for different computers
2501 recognize different instructions. In fact, the same symbol may
2502 represent a different instruction in a different computer's assembly
2506 @cindex @code{:} (label)
2507 @cindex label (@code{:})
2508 A label is a symbol immediately followed by a colon (@code{:}).
2509 Whitespace before a label or after a colon is permitted, but you may not
2510 have whitespace between a label's symbol and its colon. @xref{Labels}.
2513 For HPPA targets, labels need not be immediately followed by a colon, but
2514 the definition of a label must begin in column zero. This also implies that
2515 only one label may be defined on each line.
2519 label: .directive followed by something
2520 another_label: # This is an empty statement.
2521 instruction operand_1, operand_2, @dots{}
2528 A constant is a number, written so that its value is known by
2529 inspection, without knowing any context. Like this:
2532 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2533 .ascii "Ring the bell\7" # A string constant.
2534 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2535 .float 0f-314159265358979323846264338327\
2536 95028841971.693993751E-40 # - pi, a flonum.
2541 * Characters:: Character Constants
2542 * Numbers:: Number Constants
2546 @subsection Character Constants
2548 @cindex character constants
2549 @cindex constants, character
2550 There are two kinds of character constants. A @dfn{character} stands
2551 for one character in one byte and its value may be used in
2552 numeric expressions. String constants (properly called string
2553 @emph{literals}) are potentially many bytes and their values may not be
2554 used in arithmetic expressions.
2558 * Chars:: Characters
2562 @subsubsection Strings
2564 @cindex string constants
2565 @cindex constants, string
2566 A @dfn{string} is written between double-quotes. It may contain
2567 double-quotes or null characters. The way to get special characters
2568 into a string is to @dfn{escape} these characters: precede them with
2569 a backslash @samp{\} character. For example @samp{\\} represents
2570 one backslash: the first @code{\} is an escape which tells
2571 @command{@value{AS}} to interpret the second character literally as a backslash
2572 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2573 escape character). The complete list of escapes follows.
2575 @cindex escape codes, character
2576 @cindex character escape codes
2579 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2581 @cindex @code{\b} (backspace character)
2582 @cindex backspace (@code{\b})
2584 Mnemonic for backspace; for ASCII this is octal code 010.
2587 @c Mnemonic for EOText; for ASCII this is octal code 004.
2589 @cindex @code{\f} (formfeed character)
2590 @cindex formfeed (@code{\f})
2592 Mnemonic for FormFeed; for ASCII this is octal code 014.
2594 @cindex @code{\n} (newline character)
2595 @cindex newline (@code{\n})
2597 Mnemonic for newline; for ASCII this is octal code 012.
2600 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2602 @cindex @code{\r} (carriage return character)
2603 @cindex carriage return (@code{\r})
2605 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2608 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2609 @c other assemblers.
2611 @cindex @code{\t} (tab)
2612 @cindex tab (@code{\t})
2614 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2617 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2618 @c @item \x @var{digit} @var{digit} @var{digit}
2619 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2621 @cindex @code{\@var{ddd}} (octal character code)
2622 @cindex octal character code (@code{\@var{ddd}})
2623 @item \ @var{digit} @var{digit} @var{digit}
2624 An octal character code. The numeric code is 3 octal digits.
2625 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2626 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2628 @cindex @code{\@var{xd...}} (hex character code)
2629 @cindex hex character code (@code{\@var{xd...}})
2630 @item \@code{x} @var{hex-digits...}
2631 A hex character code. All trailing hex digits are combined. Either upper or
2632 lower case @code{x} works.
2634 @cindex @code{\\} (@samp{\} character)
2635 @cindex backslash (@code{\\})
2637 Represents one @samp{\} character.
2640 @c Represents one @samp{'} (accent acute) character.
2641 @c This is needed in single character literals
2642 @c (@xref{Characters,,Character Constants}.) to represent
2645 @cindex @code{\"} (doublequote character)
2646 @cindex doublequote (@code{\"})
2648 Represents one @samp{"} character. Needed in strings to represent
2649 this character, because an unescaped @samp{"} would end the string.
2651 @item \ @var{anything-else}
2652 Any other character when escaped by @kbd{\} gives a warning, but
2653 assembles as if the @samp{\} was not present. The idea is that if
2654 you used an escape sequence you clearly didn't want the literal
2655 interpretation of the following character. However @command{@value{AS}} has no
2656 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2657 code and warns you of the fact.
2660 Which characters are escapable, and what those escapes represent,
2661 varies widely among assemblers. The current set is what we think
2662 the BSD 4.2 assembler recognizes, and is a subset of what most C
2663 compilers recognize. If you are in doubt, do not use an escape
2667 @subsubsection Characters
2669 @cindex single character constant
2670 @cindex character, single
2671 @cindex constant, single character
2672 A single character may be written as a single quote immediately
2673 followed by that character. The same escapes apply to characters as
2674 to strings. So if you want to write the character backslash, you
2675 must write @kbd{'\\} where the first @code{\} escapes the second
2676 @code{\}. As you can see, the quote is an acute accent, not a
2677 grave accent. A newline
2679 @ifclear abnormal-separator
2680 (or semicolon @samp{;})
2682 @ifset abnormal-separator
2684 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2689 immediately following an acute accent is taken as a literal character
2690 and does not count as the end of a statement. The value of a character
2691 constant in a numeric expression is the machine's byte-wide code for
2692 that character. @command{@value{AS}} assumes your character code is ASCII:
2693 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2696 @subsection Number Constants
2698 @cindex constants, number
2699 @cindex number constants
2700 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2701 are stored in the target machine. @emph{Integers} are numbers that
2702 would fit into an @code{int} in the C language. @emph{Bignums} are
2703 integers, but they are stored in more than 32 bits. @emph{Flonums}
2704 are floating point numbers, described below.
2707 * Integers:: Integers
2712 * Bit Fields:: Bit Fields
2718 @subsubsection Integers
2720 @cindex constants, integer
2722 @cindex binary integers
2723 @cindex integers, binary
2724 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2725 the binary digits @samp{01}.
2727 @cindex octal integers
2728 @cindex integers, octal
2729 An octal integer is @samp{0} followed by zero or more of the octal
2730 digits (@samp{01234567}).
2732 @cindex decimal integers
2733 @cindex integers, decimal
2734 A decimal integer starts with a non-zero digit followed by zero or
2735 more digits (@samp{0123456789}).
2737 @cindex hexadecimal integers
2738 @cindex integers, hexadecimal
2739 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2740 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2742 Integers have the usual values. To denote a negative integer, use
2743 the prefix operator @samp{-} discussed under expressions
2744 (@pxref{Prefix Ops,,Prefix Operators}).
2747 @subsubsection Bignums
2750 @cindex constants, bignum
2751 A @dfn{bignum} has the same syntax and semantics as an integer
2752 except that the number (or its negative) takes more than 32 bits to
2753 represent in binary. The distinction is made because in some places
2754 integers are permitted while bignums are not.
2757 @subsubsection Flonums
2759 @cindex floating point numbers
2760 @cindex constants, floating point
2762 @cindex precision, floating point
2763 A @dfn{flonum} represents a floating point number. The translation is
2764 indirect: a decimal floating point number from the text is converted by
2765 @command{@value{AS}} to a generic binary floating point number of more than
2766 sufficient precision. This generic floating point number is converted
2767 to a particular computer's floating point format (or formats) by a
2768 portion of @command{@value{AS}} specialized to that computer.
2770 A flonum is written by writing (in order)
2775 (@samp{0} is optional on the HPPA.)
2779 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2781 @kbd{e} is recommended. Case is not important.
2783 @c FIXME: verify if flonum syntax really this vague for most cases
2784 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2785 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2788 On the H8/300, Renesas / SuperH SH,
2789 and AMD 29K architectures, the letter must be
2790 one of the letters @samp{DFPRSX} (in upper or lower case).
2792 On the ARC, the letter must be one of the letters @samp{DFRS}
2793 (in upper or lower case).
2795 On the Intel 960 architecture, the letter must be
2796 one of the letters @samp{DFT} (in upper or lower case).
2798 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2802 One of the letters @samp{DFRS} (in upper or lower case).
2805 One of the letters @samp{DFPRSX} (in upper or lower case).
2808 The letter @samp{E} (upper case only).
2811 One of the letters @samp{DFT} (in upper or lower case).
2816 An optional sign: either @samp{+} or @samp{-}.
2819 An optional @dfn{integer part}: zero or more decimal digits.
2822 An optional @dfn{fractional part}: @samp{.} followed by zero
2823 or more decimal digits.
2826 An optional exponent, consisting of:
2830 An @samp{E} or @samp{e}.
2831 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2832 @c principle this can perfectly well be different on different targets.
2834 Optional sign: either @samp{+} or @samp{-}.
2836 One or more decimal digits.
2841 At least one of the integer part or the fractional part must be
2842 present. The floating point number has the usual base-10 value.
2844 @command{@value{AS}} does all processing using integers. Flonums are computed
2845 independently of any floating point hardware in the computer running
2846 @command{@value{AS}}.
2850 @c Bit fields are written as a general facility but are also controlled
2851 @c by a conditional-compilation flag---which is as of now (21mar91)
2852 @c turned on only by the i960 config of GAS.
2854 @subsubsection Bit Fields
2857 @cindex constants, bit field
2858 You can also define numeric constants as @dfn{bit fields}.
2859 Specify two numbers separated by a colon---
2861 @var{mask}:@var{value}
2864 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2867 The resulting number is then packed
2869 @c this conditional paren in case bit fields turned on elsewhere than 960
2870 (in host-dependent byte order)
2872 into a field whose width depends on which assembler directive has the
2873 bit-field as its argument. Overflow (a result from the bitwise and
2874 requiring more binary digits to represent) is not an error; instead,
2875 more constants are generated, of the specified width, beginning with the
2876 least significant digits.@refill
2878 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2879 @code{.short}, and @code{.word} accept bit-field arguments.
2884 @chapter Sections and Relocation
2889 * Secs Background:: Background
2890 * Ld Sections:: Linker Sections
2891 * As Sections:: Assembler Internal Sections
2892 * Sub-Sections:: Sub-Sections
2896 @node Secs Background
2899 Roughly, a section is a range of addresses, with no gaps; all data
2900 ``in'' those addresses is treated the same for some particular purpose.
2901 For example there may be a ``read only'' section.
2903 @cindex linker, and assembler
2904 @cindex assembler, and linker
2905 The linker @code{@value{LD}} reads many object files (partial programs) and
2906 combines their contents to form a runnable program. When @command{@value{AS}}
2907 emits an object file, the partial program is assumed to start at address 0.
2908 @code{@value{LD}} assigns the final addresses for the partial program, so that
2909 different partial programs do not overlap. This is actually an
2910 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2913 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2914 addresses. These blocks slide to their run-time addresses as rigid
2915 units; their length does not change and neither does the order of bytes
2916 within them. Such a rigid unit is called a @emph{section}. Assigning
2917 run-time addresses to sections is called @dfn{relocation}. It includes
2918 the task of adjusting mentions of object-file addresses so they refer to
2919 the proper run-time addresses.
2921 For the H8/300, and for the Renesas / SuperH SH,
2922 @command{@value{AS}} pads sections if needed to
2923 ensure they end on a word (sixteen bit) boundary.
2926 @cindex standard assembler sections
2927 An object file written by @command{@value{AS}} has at least three sections, any
2928 of which may be empty. These are named @dfn{text}, @dfn{data} and
2933 When it generates COFF or ELF output,
2935 @command{@value{AS}} can also generate whatever other named sections you specify
2936 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2937 If you do not use any directives that place output in the @samp{.text}
2938 or @samp{.data} sections, these sections still exist, but are empty.
2943 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2945 @command{@value{AS}} can also generate whatever other named sections you
2946 specify using the @samp{.space} and @samp{.subspace} directives. See
2947 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2948 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2949 assembler directives.
2952 Additionally, @command{@value{AS}} uses different names for the standard
2953 text, data, and bss sections when generating SOM output. Program text
2954 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2955 BSS into @samp{$BSS$}.
2959 Within the object file, the text section starts at address @code{0}, the
2960 data section follows, and the bss section follows the data section.
2963 When generating either SOM or ELF output files on the HPPA, the text
2964 section starts at address @code{0}, the data section at address
2965 @code{0x4000000}, and the bss section follows the data section.
2968 To let @code{@value{LD}} know which data changes when the sections are
2969 relocated, and how to change that data, @command{@value{AS}} also writes to the
2970 object file details of the relocation needed. To perform relocation
2971 @code{@value{LD}} must know, each time an address in the object
2975 Where in the object file is the beginning of this reference to
2978 How long (in bytes) is this reference?
2980 Which section does the address refer to? What is the numeric value of
2982 (@var{address}) @minus{} (@var{start-address of section})?
2985 Is the reference to an address ``Program-Counter relative''?
2988 @cindex addresses, format of
2989 @cindex section-relative addressing
2990 In fact, every address @command{@value{AS}} ever uses is expressed as
2992 (@var{section}) + (@var{offset into section})
2995 Further, most expressions @command{@value{AS}} computes have this section-relative
2998 (For some object formats, such as SOM for the HPPA, some expressions are
2999 symbol-relative instead.)
3002 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
3003 @var{N} into section @var{secname}.''
3005 Apart from text, data and bss sections you need to know about the
3006 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
3007 addresses in the absolute section remain unchanged. For example, address
3008 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
3009 @code{@value{LD}}. Although the linker never arranges two partial programs'
3010 data sections with overlapping addresses after linking, @emph{by definition}
3011 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
3012 part of a program is always the same address when the program is running as
3013 address @code{@{absolute@ 239@}} in any other part of the program.
3015 The idea of sections is extended to the @dfn{undefined} section. Any
3016 address whose section is unknown at assembly time is by definition
3017 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
3018 Since numbers are always defined, the only way to generate an undefined
3019 address is to mention an undefined symbol. A reference to a named
3020 common block would be such a symbol: its value is unknown at assembly
3021 time so it has section @emph{undefined}.
3023 By analogy the word @emph{section} is used to describe groups of sections in
3024 the linked program. @code{@value{LD}} puts all partial programs' text
3025 sections in contiguous addresses in the linked program. It is
3026 customary to refer to the @emph{text section} of a program, meaning all
3027 the addresses of all partial programs' text sections. Likewise for
3028 data and bss sections.
3030 Some sections are manipulated by @code{@value{LD}}; others are invented for
3031 use of @command{@value{AS}} and have no meaning except during assembly.
3034 @section Linker Sections
3035 @code{@value{LD}} deals with just four kinds of sections, summarized below.
3040 @cindex named sections
3041 @cindex sections, named
3042 @item named sections
3045 @cindex text section
3046 @cindex data section
3050 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
3051 separate but equal sections. Anything you can say of one section is
3054 When the program is running, however, it is
3055 customary for the text section to be unalterable. The
3056 text section is often shared among processes: it contains
3057 instructions, constants and the like. The data section of a running
3058 program is usually alterable: for example, C variables would be stored
3059 in the data section.
3064 This section contains zeroed bytes when your program begins running. It
3065 is used to hold uninitialized variables or common storage. The length of
3066 each partial program's bss section is important, but because it starts
3067 out containing zeroed bytes there is no need to store explicit zero
3068 bytes in the object file. The bss section was invented to eliminate
3069 those explicit zeros from object files.
3071 @cindex absolute section
3072 @item absolute section
3073 Address 0 of this section is always ``relocated'' to runtime address 0.
3074 This is useful if you want to refer to an address that @code{@value{LD}} must
3075 not change when relocating. In this sense we speak of absolute
3076 addresses being ``unrelocatable'': they do not change during relocation.
3078 @cindex undefined section
3079 @item undefined section
3080 This ``section'' is a catch-all for address references to objects not in
3081 the preceding sections.
3082 @c FIXME: ref to some other doc on obj-file formats could go here.
3085 @cindex relocation example
3086 An idealized example of three relocatable sections follows.
3088 The example uses the traditional section names @samp{.text} and @samp{.data}.
3090 Memory addresses are on the horizontal axis.
3094 @c END TEXI2ROFF-KILL
3097 partial program # 1: |ttttt|dddd|00|
3104 partial program # 2: |TTT|DDD|000|
3107 +--+---+-----+--+----+---+-----+~~
3108 linked program: | |TTT|ttttt| |dddd|DDD|00000|
3109 +--+---+-----+--+----+---+-----+~~
3111 addresses: 0 @dots{}
3118 \line{\it Partial program \#1: \hfil}
3119 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3120 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
3122 \line{\it Partial program \#2: \hfil}
3123 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3124 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
3126 \line{\it linked program: \hfil}
3127 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
3128 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
3129 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
3130 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
3132 \line{\it addresses: \hfil}
3136 @c END TEXI2ROFF-KILL
3139 @section Assembler Internal Sections
3141 @cindex internal assembler sections
3142 @cindex sections in messages, internal
3143 These sections are meant only for the internal use of @command{@value{AS}}. They
3144 have no meaning at run-time. You do not really need to know about these
3145 sections for most purposes; but they can be mentioned in @command{@value{AS}}
3146 warning messages, so it might be helpful to have an idea of their
3147 meanings to @command{@value{AS}}. These sections are used to permit the
3148 value of every expression in your assembly language program to be a
3149 section-relative address.
3152 @cindex assembler internal logic error
3153 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
3154 An internal assembler logic error has been found. This means there is a
3155 bug in the assembler.
3157 @cindex expr (internal section)
3159 The assembler stores complex expression internally as combinations of
3160 symbols. When it needs to represent an expression as a symbol, it puts
3161 it in the expr section.
3163 @c FIXME item transfer[t] vector preload
3164 @c FIXME item transfer[t] vector postload
3165 @c FIXME item register
3169 @section Sub-Sections
3171 @cindex numbered subsections
3172 @cindex grouping data
3178 fall into two sections: text and data.
3180 You may have separate groups of
3182 data in named sections
3186 data in named sections
3192 that you want to end up near to each other in the object file, even though they
3193 are not contiguous in the assembler source. @command{@value{AS}} allows you to
3194 use @dfn{subsections} for this purpose. Within each section, there can be
3195 numbered subsections with values from 0 to 8192. Objects assembled into the
3196 same subsection go into the object file together with other objects in the same
3197 subsection. For example, a compiler might want to store constants in the text
3198 section, but might not want to have them interspersed with the program being
3199 assembled. In this case, the compiler could issue a @samp{.text 0} before each
3200 section of code being output, and a @samp{.text 1} before each group of
3201 constants being output.
3203 Subsections are optional. If you do not use subsections, everything
3204 goes in subsection number zero.
3207 Each subsection is zero-padded up to a multiple of four bytes.
3208 (Subsections may be padded a different amount on different flavors
3209 of @command{@value{AS}}.)
3213 On the H8/300 platform, each subsection is zero-padded to a word
3214 boundary (two bytes).
3215 The same is true on the Renesas SH.
3218 @c FIXME section padding (alignment)?
3219 @c Rich Pixley says padding here depends on target obj code format; that
3220 @c doesn't seem particularly useful to say without further elaboration,
3221 @c so for now I say nothing about it. If this is a generic BFD issue,
3222 @c these paragraphs might need to vanish from this manual, and be
3223 @c discussed in BFD chapter of binutils (or some such).
3227 Subsections appear in your object file in numeric order, lowest numbered
3228 to highest. (All this to be compatible with other people's assemblers.)
3229 The object file contains no representation of subsections; @code{@value{LD}} and
3230 other programs that manipulate object files see no trace of them.
3231 They just see all your text subsections as a text section, and all your
3232 data subsections as a data section.
3234 To specify which subsection you want subsequent statements assembled
3235 into, use a numeric argument to specify it, in a @samp{.text
3236 @var{expression}} or a @samp{.data @var{expression}} statement.
3239 When generating COFF output, you
3244 can also use an extra subsection
3245 argument with arbitrary named sections: @samp{.section @var{name},
3250 When generating ELF output, you
3255 can also use the @code{.subsection} directive (@pxref{SubSection})
3256 to specify a subsection: @samp{.subsection @var{expression}}.
3258 @var{Expression} should be an absolute expression
3259 (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0}
3260 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3261 begins in @code{text 0}. For instance:
3263 .text 0 # The default subsection is text 0 anyway.
3264 .ascii "This lives in the first text subsection. *"
3266 .ascii "But this lives in the second text subsection."
3268 .ascii "This lives in the data section,"
3269 .ascii "in the first data subsection."
3271 .ascii "This lives in the first text section,"
3272 .ascii "immediately following the asterisk (*)."
3275 Each section has a @dfn{location counter} incremented by one for every byte
3276 assembled into that section. Because subsections are merely a convenience
3277 restricted to @command{@value{AS}} there is no concept of a subsection location
3278 counter. There is no way to directly manipulate a location counter---but the
3279 @code{.align} directive changes it, and any label definition captures its
3280 current value. The location counter of the section where statements are being
3281 assembled is said to be the @dfn{active} location counter.
3284 @section bss Section
3287 @cindex common variable storage
3288 The bss section is used for local common variable storage.
3289 You may allocate address space in the bss section, but you may
3290 not dictate data to load into it before your program executes. When
3291 your program starts running, all the contents of the bss
3292 section are zeroed bytes.
3294 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3295 @ref{Lcomm,,@code{.lcomm}}.
3297 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3298 another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}.
3301 When assembling for a target which supports multiple sections, such as ELF or
3302 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3303 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3304 section. Typically the section will only contain symbol definitions and
3305 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3312 Symbols are a central concept: the programmer uses symbols to name
3313 things, the linker uses symbols to link, and the debugger uses symbols
3317 @cindex debuggers, and symbol order
3318 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3319 the same order they were declared. This may break some debuggers.
3324 * Setting Symbols:: Giving Symbols Other Values
3325 * Symbol Names:: Symbol Names
3326 * Dot:: The Special Dot Symbol
3327 * Symbol Attributes:: Symbol Attributes
3334 A @dfn{label} is written as a symbol immediately followed by a colon
3335 @samp{:}. The symbol then represents the current value of the
3336 active location counter, and is, for example, a suitable instruction
3337 operand. You are warned if you use the same symbol to represent two
3338 different locations: the first definition overrides any other
3342 On the HPPA, the usual form for a label need not be immediately followed by a
3343 colon, but instead must start in column zero. Only one label may be defined on
3344 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3345 provides a special directive @code{.label} for defining labels more flexibly.
3348 @node Setting Symbols
3349 @section Giving Symbols Other Values
3351 @cindex assigning values to symbols
3352 @cindex symbol values, assigning
3353 A symbol can be given an arbitrary value by writing a symbol, followed
3354 by an equals sign @samp{=}, followed by an expression
3355 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3356 directive. @xref{Set,,@code{.set}}. In the same way, using a double
3357 equals sign @samp{=}@samp{=} here represents an equivalent of the
3358 @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}.
3361 Blackfin does not support symbol assignment with @samp{=}.
3365 @section Symbol Names
3367 @cindex symbol names
3368 @cindex names, symbol
3369 @ifclear SPECIAL-SYMS
3370 Symbol names begin with a letter or with one of @samp{._}. On most
3371 machines, you can also use @code{$} in symbol names; exceptions are
3372 noted in @ref{Machine Dependencies}. That character may be followed by any
3373 string of digits, letters, dollar signs (unless otherwise noted for a
3374 particular target machine), and underscores.
3378 Symbol names begin with a letter or with one of @samp{._}. On the
3379 Renesas SH you can also use @code{$} in symbol names. That
3380 character may be followed by any string of digits, letters, dollar signs (save
3381 on the H8/300), and underscores.
3385 Case of letters is significant: @code{foo} is a different symbol name
3388 Each symbol has exactly one name. Each name in an assembly language program
3389 refers to exactly one symbol. You may use that symbol name any number of times
3392 @subheading Local Symbol Names
3394 @cindex local symbol names
3395 @cindex symbol names, local
3396 A local symbol is any symbol beginning with certain local label prefixes.
3397 By default, the local label prefix is @samp{.L} for ELF systems or
3398 @samp{L} for traditional a.out systems, but each target may have its own
3399 set of local label prefixes.
3401 On the HPPA local symbols begin with @samp{L$}.
3404 Local symbols are defined and used within the assembler, but they are
3405 normally not saved in object files. Thus, they are not visible when debugging.
3406 You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols:
3407 @option{-L}}) to retain the local symbols in the object files.
3409 @subheading Local Labels
3411 @cindex local labels
3412 @cindex temporary symbol names
3413 @cindex symbol names, temporary
3414 Local labels help compilers and programmers use names temporarily.
3415 They create symbols which are guaranteed to be unique over the entire scope of
3416 the input source code and which can be referred to by a simple notation.
3417 To define a local label, write a label of the form @samp{@b{N}:} (where @b{N}
3418 represents any positive integer). To refer to the most recent previous
3419 definition of that label write @samp{@b{N}b}, using the same number as when
3420 you defined the label. To refer to the next definition of a local label, write
3421 @samp{@b{N}f}---the @samp{b} stands for ``backwards'' and the @samp{f} stands
3424 There is no restriction on how you can use these labels, and you can reuse them
3425 too. So that it is possible to repeatedly define the same local label (using
3426 the same number @samp{@b{N}}), although you can only refer to the most recently
3427 defined local label of that number (for a backwards reference) or the next
3428 definition of a specific local label for a forward reference. It is also worth
3429 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3430 implemented in a slightly more efficient manner than the others.
3441 Which is the equivalent of:
3444 label_1: branch label_3
3445 label_2: branch label_1
3446 label_3: branch label_4
3447 label_4: branch label_3
3450 Local label names are only a notational device. They are immediately
3451 transformed into more conventional symbol names before the assembler uses them.
3452 The symbol names are stored in the symbol table, appear in error messages, and
3453 are optionally emitted to the object file. The names are constructed using
3457 @item @emph{local label prefix}
3458 All local symbols begin with the system-specific local label prefix.
3459 Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols
3460 that start with the local label prefix. These labels are
3461 used for symbols you are never intended to see. If you use the
3462 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3463 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3464 you may use them in debugging.
3467 This is the number that was used in the local label definition. So if the
3468 label is written @samp{55:} then the number is @samp{55}.
3471 This unusual character is included so you do not accidentally invent a symbol
3472 of the same name. The character has ASCII value of @samp{\002} (control-B).
3474 @item @emph{ordinal number}
3475 This is a serial number to keep the labels distinct. The first definition of
3476 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3477 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3478 the number @samp{1} and its 15th definition gets @samp{15} as well.
3481 So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and
3482 the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}.
3484 @subheading Dollar Local Labels
3485 @cindex dollar local symbols
3487 @code{@value{AS}} also supports an even more local form of local labels called
3488 dollar labels. These labels go out of scope (i.e., they become undefined) as
3489 soon as a non-local label is defined. Thus they remain valid for only a small
3490 region of the input source code. Normal local labels, by contrast, remain in
3491 scope for the entire file, or until they are redefined by another occurrence of
3492 the same local label.
3494 Dollar labels are defined in exactly the same way as ordinary local labels,
3495 except that they have a dollar sign suffix to their numeric value, e.g.,
3498 They can also be distinguished from ordinary local labels by their transformed
3499 names which use ASCII character @samp{\001} (control-A) as the magic character
3500 to distinguish them from ordinary labels. For example, the fifth definition of
3501 @samp{6$} may be named @samp{.L6@kbd{C-A}5}.
3504 @section The Special Dot Symbol
3506 @cindex dot (symbol)
3507 @cindex @code{.} (symbol)
3508 @cindex current address
3509 @cindex location counter
3510 The special symbol @samp{.} refers to the current address that
3511 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3512 .long .} defines @code{melvin} to contain its own address.
3513 Assigning a value to @code{.} is treated the same as a @code{.org}
3515 @ifclear no-space-dir
3516 Thus, the expression @samp{.=.+4} is the same as saying
3520 @node Symbol Attributes
3521 @section Symbol Attributes
3523 @cindex symbol attributes
3524 @cindex attributes, symbol
3525 Every symbol has, as well as its name, the attributes ``Value'' and
3526 ``Type''. Depending on output format, symbols can also have auxiliary
3529 The detailed definitions are in @file{a.out.h}.
3532 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3533 all these attributes, and probably won't warn you. This makes the
3534 symbol an externally defined symbol, which is generally what you
3538 * Symbol Value:: Value
3539 * Symbol Type:: Type
3542 * a.out Symbols:: Symbol Attributes: @code{a.out}
3546 * a.out Symbols:: Symbol Attributes: @code{a.out}
3549 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3554 * COFF Symbols:: Symbol Attributes for COFF
3557 * SOM Symbols:: Symbol Attributes for SOM
3564 @cindex value of a symbol
3565 @cindex symbol value
3566 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3567 location in the text, data, bss or absolute sections the value is the
3568 number of addresses from the start of that section to the label.
3569 Naturally for text, data and bss sections the value of a symbol changes
3570 as @code{@value{LD}} changes section base addresses during linking. Absolute
3571 symbols' values do not change during linking: that is why they are
3574 The value of an undefined symbol is treated in a special way. If it is
3575 0 then the symbol is not defined in this assembler source file, and
3576 @code{@value{LD}} tries to determine its value from other files linked into the
3577 same program. You make this kind of symbol simply by mentioning a symbol
3578 name without defining it. A non-zero value represents a @code{.comm}
3579 common declaration. The value is how much common storage to reserve, in
3580 bytes (addresses). The symbol refers to the first address of the
3586 @cindex type of a symbol
3588 The type attribute of a symbol contains relocation (section)
3589 information, any flag settings indicating that a symbol is external, and
3590 (optionally), other information for linkers and debuggers. The exact
3591 format depends on the object-code output format in use.
3596 @c The following avoids a "widow" subsection title. @group would be
3597 @c better if it were available outside examples.
3600 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3602 @cindex @code{b.out} symbol attributes
3603 @cindex symbol attributes, @code{b.out}
3604 These symbol attributes appear only when @command{@value{AS}} is configured for
3605 one of the Berkeley-descended object output formats---@code{a.out} or
3611 @subsection Symbol Attributes: @code{a.out}
3613 @cindex @code{a.out} symbol attributes
3614 @cindex symbol attributes, @code{a.out}
3620 @subsection Symbol Attributes: @code{a.out}
3622 @cindex @code{a.out} symbol attributes
3623 @cindex symbol attributes, @code{a.out}
3627 * Symbol Desc:: Descriptor
3628 * Symbol Other:: Other
3632 @subsubsection Descriptor
3634 @cindex descriptor, of @code{a.out} symbol
3635 This is an arbitrary 16-bit value. You may establish a symbol's
3636 descriptor value by using a @code{.desc} statement
3637 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3638 @command{@value{AS}}.
3641 @subsubsection Other
3643 @cindex other attribute, of @code{a.out} symbol
3644 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3649 @subsection Symbol Attributes for COFF
3651 @cindex COFF symbol attributes
3652 @cindex symbol attributes, COFF
3654 The COFF format supports a multitude of auxiliary symbol attributes;
3655 like the primary symbol attributes, they are set between @code{.def} and
3656 @code{.endef} directives.
3658 @subsubsection Primary Attributes
3660 @cindex primary attributes, COFF symbols
3661 The symbol name is set with @code{.def}; the value and type,
3662 respectively, with @code{.val} and @code{.type}.
3664 @subsubsection Auxiliary Attributes
3666 @cindex auxiliary attributes, COFF symbols
3667 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3668 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3669 table information for COFF.
3674 @subsection Symbol Attributes for SOM
3676 @cindex SOM symbol attributes
3677 @cindex symbol attributes, SOM
3679 The SOM format for the HPPA supports a multitude of symbol attributes set with
3680 the @code{.EXPORT} and @code{.IMPORT} directives.
3682 The attributes are described in @cite{HP9000 Series 800 Assembly
3683 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3684 @code{EXPORT} assembler directive documentation.
3688 @chapter Expressions
3692 @cindex numeric values
3693 An @dfn{expression} specifies an address or numeric value.
3694 Whitespace may precede and/or follow an expression.
3696 The result of an expression must be an absolute number, or else an offset into
3697 a particular section. If an expression is not absolute, and there is not
3698 enough information when @command{@value{AS}} sees the expression to know its
3699 section, a second pass over the source program might be necessary to interpret
3700 the expression---but the second pass is currently not implemented.
3701 @command{@value{AS}} aborts with an error message in this situation.
3704 * Empty Exprs:: Empty Expressions
3705 * Integer Exprs:: Integer Expressions
3709 @section Empty Expressions
3711 @cindex empty expressions
3712 @cindex expressions, empty
3713 An empty expression has no value: it is just whitespace or null.
3714 Wherever an absolute expression is required, you may omit the
3715 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3716 is compatible with other assemblers.
3719 @section Integer Expressions
3721 @cindex integer expressions
3722 @cindex expressions, integer
3723 An @dfn{integer expression} is one or more @emph{arguments} delimited
3724 by @emph{operators}.
3727 * Arguments:: Arguments
3728 * Operators:: Operators
3729 * Prefix Ops:: Prefix Operators
3730 * Infix Ops:: Infix Operators
3734 @subsection Arguments
3736 @cindex expression arguments
3737 @cindex arguments in expressions
3738 @cindex operands in expressions
3739 @cindex arithmetic operands
3740 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3741 contexts arguments are sometimes called ``arithmetic operands''. In
3742 this manual, to avoid confusing them with the ``instruction operands'' of
3743 the machine language, we use the term ``argument'' to refer to parts of
3744 expressions only, reserving the word ``operand'' to refer only to machine
3745 instruction operands.
3747 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3748 @var{section} is one of text, data, bss, absolute,
3749 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3752 Numbers are usually integers.
3754 A number can be a flonum or bignum. In this case, you are warned
3755 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3756 these 32 bits are an integer. You may write integer-manipulating
3757 instructions that act on exotic constants, compatible with other
3760 @cindex subexpressions
3761 Subexpressions are a left parenthesis @samp{(} followed by an integer
3762 expression, followed by a right parenthesis @samp{)}; or a prefix
3763 operator followed by an argument.
3766 @subsection Operators
3768 @cindex operators, in expressions
3769 @cindex arithmetic functions
3770 @cindex functions, in expressions
3771 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3772 operators are followed by an argument. Infix operators appear
3773 between their arguments. Operators may be preceded and/or followed by
3777 @subsection Prefix Operator
3779 @cindex prefix operators
3780 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3781 one argument, which must be absolute.
3783 @c the tex/end tex stuff surrounding this small table is meant to make
3784 @c it align, on the printed page, with the similar table in the next
3785 @c section (which is inside an enumerate).
3787 \global\advance\leftskip by \itemindent
3792 @dfn{Negation}. Two's complement negation.
3794 @dfn{Complementation}. Bitwise not.
3798 \global\advance\leftskip by -\itemindent
3802 @subsection Infix Operators
3804 @cindex infix operators
3805 @cindex operators, permitted arguments
3806 @dfn{Infix operators} take two arguments, one on either side. Operators
3807 have precedence, but operations with equal precedence are performed left
3808 to right. Apart from @code{+} or @option{-}, both arguments must be
3809 absolute, and the result is absolute.
3812 @cindex operator precedence
3813 @cindex precedence of operators
3820 @dfn{Multiplication}.
3823 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3829 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3832 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3836 Intermediate precedence
3841 @dfn{Bitwise Inclusive Or}.
3847 @dfn{Bitwise Exclusive Or}.
3850 @dfn{Bitwise Or Not}.
3857 @cindex addition, permitted arguments
3858 @cindex plus, permitted arguments
3859 @cindex arguments for addition
3861 @dfn{Addition}. If either argument is absolute, the result has the section of
3862 the other argument. You may not add together arguments from different
3865 @cindex subtraction, permitted arguments
3866 @cindex minus, permitted arguments
3867 @cindex arguments for subtraction
3869 @dfn{Subtraction}. If the right argument is absolute, the
3870 result has the section of the left argument.
3871 If both arguments are in the same section, the result is absolute.
3872 You may not subtract arguments from different sections.
3873 @c FIXME is there still something useful to say about undefined - undefined ?
3875 @cindex comparison expressions
3876 @cindex expressions, comparison
3881 @dfn{Is Not Equal To}
3885 @dfn{Is Greater Than}
3887 @dfn{Is Greater Than Or Equal To}
3889 @dfn{Is Less Than Or Equal To}
3891 The comparison operators can be used as infix operators. A true results has a
3892 value of -1 whereas a false result has a value of 0. Note, these operators
3893 perform signed comparisons.
3896 @item Lowest Precedence
3905 These two logical operations can be used to combine the results of sub
3906 expressions. Note, unlike the comparison operators a true result returns a
3907 value of 1 but a false results does still return 0. Also note that the logical
3908 or operator has a slightly lower precedence than logical and.
3913 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3914 address; you can only have a defined section in one of the two arguments.
3917 @chapter Assembler Directives
3919 @cindex directives, machine independent
3920 @cindex pseudo-ops, machine independent
3921 @cindex machine independent directives
3922 All assembler directives have names that begin with a period (@samp{.}).
3923 The rest of the name is letters, usually in lower case.
3925 This chapter discusses directives that are available regardless of the
3926 target machine configuration for the @sc{gnu} assembler.
3928 Some machine configurations provide additional directives.
3929 @xref{Machine Dependencies}.
3932 @ifset machine-directives
3933 @xref{Machine Dependencies}, for additional directives.
3938 * Abort:: @code{.abort}
3940 * ABORT (COFF):: @code{.ABORT}
3943 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3944 * Altmacro:: @code{.altmacro}
3945 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3946 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3947 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3948 * Byte:: @code{.byte @var{expressions}}
3949 * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
3950 * Comm:: @code{.comm @var{symbol} , @var{length} }
3951 * Data:: @code{.data @var{subsection}}
3953 * Def:: @code{.def @var{name}}
3956 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3962 * Double:: @code{.double @var{flonums}}
3963 * Eject:: @code{.eject}
3964 * Else:: @code{.else}
3965 * Elseif:: @code{.elseif}
3968 * Endef:: @code{.endef}
3971 * Endfunc:: @code{.endfunc}
3972 * Endif:: @code{.endif}
3973 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3974 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3975 * Eqv:: @code{.eqv @var{symbol}, @var{expression}}
3977 * Error:: @code{.error @var{string}}
3978 * Exitm:: @code{.exitm}
3979 * Extern:: @code{.extern}
3980 * Fail:: @code{.fail}
3981 * File:: @code{.file}
3982 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3983 * Float:: @code{.float @var{flonums}}
3984 * Func:: @code{.func}
3985 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3987 * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
3988 * Hidden:: @code{.hidden @var{names}}
3991 * hword:: @code{.hword @var{expressions}}
3992 * Ident:: @code{.ident}
3993 * If:: @code{.if @var{absolute expression}}
3994 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3995 * Include:: @code{.include "@var{file}"}
3996 * Int:: @code{.int @var{expressions}}
3998 * Internal:: @code{.internal @var{names}}
4001 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
4002 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
4003 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
4004 * Lflags:: @code{.lflags}
4005 @ifclear no-line-dir
4006 * Line:: @code{.line @var{line-number}}
4009 * Linkonce:: @code{.linkonce [@var{type}]}
4010 * List:: @code{.list}
4011 * Ln:: @code{.ln @var{line-number}}
4012 * Loc:: @code{.loc @var{fileno} @var{lineno}}
4013 * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}}
4015 * Local:: @code{.local @var{names}}
4018 * Long:: @code{.long @var{expressions}}
4020 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
4023 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
4024 * MRI:: @code{.mri @var{val}}
4025 * Noaltmacro:: @code{.noaltmacro}
4026 * Nolist:: @code{.nolist}
4027 * Octa:: @code{.octa @var{bignums}}
4028 * Org:: @code{.org @var{new-lc}, @var{fill}}
4029 * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4031 * PopSection:: @code{.popsection}
4032 * Previous:: @code{.previous}
4035 * Print:: @code{.print @var{string}}
4037 * Protected:: @code{.protected @var{names}}
4040 * Psize:: @code{.psize @var{lines}, @var{columns}}
4041 * Purgem:: @code{.purgem @var{name}}
4043 * PushSection:: @code{.pushsection @var{name}}
4046 * Quad:: @code{.quad @var{bignums}}
4047 * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
4048 * Rept:: @code{.rept @var{count}}
4049 * Sbttl:: @code{.sbttl "@var{subheading}"}
4051 * Scl:: @code{.scl @var{class}}
4054 * Section:: @code{.section @var{name}[, @var{flags}]}
4057 * Set:: @code{.set @var{symbol}, @var{expression}}
4058 * Short:: @code{.short @var{expressions}}
4059 * Single:: @code{.single @var{flonums}}
4061 * Size:: @code{.size [@var{name} , @var{expression}]}
4063 @ifclear no-space-dir
4064 * Skip:: @code{.skip @var{size} , @var{fill}}
4067 * Sleb128:: @code{.sleb128 @var{expressions}}
4068 @ifclear no-space-dir
4069 * Space:: @code{.space @var{size} , @var{fill}}
4072 * Stab:: @code{.stabd, .stabn, .stabs}
4075 * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
4076 * Struct:: @code{.struct @var{expression}}
4078 * SubSection:: @code{.subsection}
4079 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
4083 * Tag:: @code{.tag @var{structname}}
4086 * Text:: @code{.text @var{subsection}}
4087 * Title:: @code{.title "@var{heading}"}
4089 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
4092 * Uleb128:: @code{.uleb128 @var{expressions}}
4094 * Val:: @code{.val @var{addr}}
4098 * Version:: @code{.version "@var{string}"}
4099 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
4100 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
4103 * Warning:: @code{.warning @var{string}}
4104 * Weak:: @code{.weak @var{names}}
4105 * Weakref:: @code{.weakref @var{alias}, @var{symbol}}
4106 * Word:: @code{.word @var{expressions}}
4107 * Deprecated:: Deprecated Directives
4111 @section @code{.abort}
4113 @cindex @code{abort} directive
4114 @cindex stopping the assembly
4115 This directive stops the assembly immediately. It is for
4116 compatibility with other assemblers. The original idea was that the
4117 assembly language source would be piped into the assembler. If the sender
4118 of the source quit, it could use this directive tells @command{@value{AS}} to
4119 quit also. One day @code{.abort} will not be supported.
4123 @section @code{.ABORT} (COFF)
4125 @cindex @code{ABORT} directive
4126 When producing COFF output, @command{@value{AS}} accepts this directive as a
4127 synonym for @samp{.abort}.
4130 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
4136 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4138 @cindex padding the location counter
4139 @cindex @code{align} directive
4140 Pad the location counter (in the current subsection) to a particular storage
4141 boundary. The first expression (which must be absolute) is the alignment
4142 required, as described below.
4144 The second expression (also absolute) gives the fill value to be stored in the
4145 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4146 padding bytes are normally zero. However, on some systems, if the section is
4147 marked as containing code and the fill value is omitted, the space is filled
4148 with no-op instructions.
4150 The third expression is also absolute, and is also optional. If it is present,
4151 it is the maximum number of bytes that should be skipped by this alignment
4152 directive. If doing the alignment would require skipping more bytes than the
4153 specified maximum, then the alignment is not done at all. You can omit the
4154 fill value (the second argument) entirely by simply using two commas after the
4155 required alignment; this can be useful if you want the alignment to be filled
4156 with no-op instructions when appropriate.
4158 The way the required alignment is specified varies from system to system.
4159 For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32,
4160 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
4161 alignment request in bytes. For example @samp{.align 8} advances
4162 the location counter until it is a multiple of 8. If the location counter
4163 is already a multiple of 8, no change is needed. For the tic54x, the
4164 first expression is the alignment request in words.
4166 For other systems, including ppc, i386 using a.out format, arm and
4167 strongarm, it is the
4168 number of low-order zero bits the location counter must have after
4169 advancement. For example @samp{.align 3} advances the location
4170 counter until it a multiple of 8. If the location counter is already a
4171 multiple of 8, no change is needed.
4173 This inconsistency is due to the different behaviors of the various
4174 native assemblers for these systems which GAS must emulate.
4175 GAS also provides @code{.balign} and @code{.p2align} directives,
4176 described later, which have a consistent behavior across all
4177 architectures (but are specific to GAS).
4180 @section @code{.altmacro}
4181 Enable alternate macro mode, enabling:
4184 @item LOCAL @var{name} [ , @dots{} ]
4185 One additional directive, @code{LOCAL}, is available. It is used to
4186 generate a string replacement for each of the @var{name} arguments, and
4187 replace any instances of @var{name} in each macro expansion. The
4188 replacement string is unique in the assembly, and different for each
4189 separate macro expansion. @code{LOCAL} allows you to write macros that
4190 define symbols, without fear of conflict between separate macro expansions.
4192 @item String delimiters
4193 You can write strings delimited in these other ways besides
4194 @code{"@var{string}"}:
4197 @item '@var{string}'
4198 You can delimit strings with single-quote characters.
4200 @item <@var{string}>
4201 You can delimit strings with matching angle brackets.
4204 @item single-character string escape
4205 To include any single character literally in a string (even if the
4206 character would otherwise have some special meaning), you can prefix the
4207 character with @samp{!} (an exclamation mark). For example, you can
4208 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4210 @item Expression results as strings
4211 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4212 and use the result as a string.
4216 @section @code{.ascii "@var{string}"}@dots{}
4218 @cindex @code{ascii} directive
4219 @cindex string literals
4220 @code{.ascii} expects zero or more string literals (@pxref{Strings})
4221 separated by commas. It assembles each string (with no automatic
4222 trailing zero byte) into consecutive addresses.
4225 @section @code{.asciz "@var{string}"}@dots{}
4227 @cindex @code{asciz} directive
4228 @cindex zero-terminated strings
4229 @cindex null-terminated strings
4230 @code{.asciz} is just like @code{.ascii}, but each string is followed by
4231 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
4234 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4236 @cindex padding the location counter given number of bytes
4237 @cindex @code{balign} directive
4238 Pad the location counter (in the current subsection) to a particular
4239 storage boundary. The first expression (which must be absolute) is the
4240 alignment request in bytes. For example @samp{.balign 8} advances
4241 the location counter until it is a multiple of 8. If the location counter
4242 is already a multiple of 8, no change is needed.
4244 The second expression (also absolute) gives the fill value to be stored in the
4245 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4246 padding bytes are normally zero. However, on some systems, if the section is
4247 marked as containing code and the fill value is omitted, the space is filled
4248 with no-op instructions.
4250 The third expression is also absolute, and is also optional. If it is present,
4251 it is the maximum number of bytes that should be skipped by this alignment
4252 directive. If doing the alignment would require skipping more bytes than the
4253 specified maximum, then the alignment is not done at all. You can omit the
4254 fill value (the second argument) entirely by simply using two commas after the
4255 required alignment; this can be useful if you want the alignment to be filled
4256 with no-op instructions when appropriate.
4258 @cindex @code{balignw} directive
4259 @cindex @code{balignl} directive
4260 The @code{.balignw} and @code{.balignl} directives are variants of the
4261 @code{.balign} directive. The @code{.balignw} directive treats the fill
4262 pattern as a two byte word value. The @code{.balignl} directives treats the
4263 fill pattern as a four byte longword value. For example, @code{.balignw
4264 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4265 filled in with the value 0x368d (the exact placement of the bytes depends upon
4266 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4270 @section @code{.byte @var{expressions}}
4272 @cindex @code{byte} directive
4273 @cindex integers, one byte
4274 @code{.byte} expects zero or more expressions, separated by commas.
4275 Each expression is assembled into the next byte.
4277 @node CFI directives
4278 @section @code{.cfi_sections @var{section_list}}
4279 @cindex @code{cfi_sections} directive
4280 @code{.cfi_sections} may be used to specify whether CFI directives
4281 should emit @code{.eh_frame} section and/or @code{.debug_frame} section.
4282 If @var{section_list} is @code{.eh_frame}, @code{.eh_frame} is emitted,
4283 if @var{section_list} is @code{.debug_frame}, @code{.debug_frame} is emitted.
4284 To emit both use @code{.eh_frame, .debug_frame}. The default if this
4285 directive is not used is @code{.cfi_sections .eh_frame}.
4287 @section @code{.cfi_startproc [simple]}
4288 @cindex @code{cfi_startproc} directive
4289 @code{.cfi_startproc} is used at the beginning of each function that
4290 should have an entry in @code{.eh_frame}. It initializes some internal
4291 data structures. Don't forget to close the function by
4292 @code{.cfi_endproc}.
4294 Unless @code{.cfi_startproc} is used along with parameter @code{simple}
4295 it also emits some architecture dependent initial CFI instructions.
4297 @section @code{.cfi_endproc}
4298 @cindex @code{cfi_endproc} directive
4299 @code{.cfi_endproc} is used at the end of a function where it closes its
4300 unwind entry previously opened by
4301 @code{.cfi_startproc}, and emits it to @code{.eh_frame}.
4303 @section @code{.cfi_personality @var{encoding} [, @var{exp}]}
4304 @code{.cfi_personality} defines personality routine and its encoding.
4305 @var{encoding} must be a constant determining how the personality
4306 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4307 argument is not present, otherwise second argument should be
4308 a constant or a symbol name. When using indirect encodings,
4309 the symbol provided should be the location where personality
4310 can be loaded from, not the personality routine itself.
4311 The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff},
4312 no personality routine.
4314 @section @code{.cfi_lsda @var{encoding} [, @var{exp}]}
4315 @code{.cfi_lsda} defines LSDA and its encoding.
4316 @var{encoding} must be a constant determining how the LSDA
4317 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4318 argument is not present, otherwise second argument should be a constant
4319 or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff},
4322 @section @code{.cfi_def_cfa @var{register}, @var{offset}}
4323 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4324 address from @var{register} and add @var{offset} to it}.
4326 @section @code{.cfi_def_cfa_register @var{register}}
4327 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4328 now on @var{register} will be used instead of the old one. Offset
4331 @section @code{.cfi_def_cfa_offset @var{offset}}
4332 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4333 remains the same, but @var{offset} is new. Note that it is the
4334 absolute offset that will be added to a defined register to compute
4337 @section @code{.cfi_adjust_cfa_offset @var{offset}}
4338 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4339 value that is added/substracted from the previous offset.
4341 @section @code{.cfi_offset @var{register}, @var{offset}}
4342 Previous value of @var{register} is saved at offset @var{offset} from
4345 @section @code{.cfi_rel_offset @var{register}, @var{offset}}
4346 Previous value of @var{register} is saved at offset @var{offset} from
4347 the current CFA register. This is transformed to @code{.cfi_offset}
4348 using the known displacement of the CFA register from the CFA.
4349 This is often easier to use, because the number will match the
4350 code it's annotating.
4352 @section @code{.cfi_register @var{register1}, @var{register2}}
4353 Previous value of @var{register1} is saved in register @var{register2}.
4355 @section @code{.cfi_restore @var{register}}
4356 @code{.cfi_restore} says that the rule for @var{register} is now the
4357 same as it was at the beginning of the function, after all initial
4358 instruction added by @code{.cfi_startproc} were executed.
4360 @section @code{.cfi_undefined @var{register}}
4361 From now on the previous value of @var{register} can't be restored anymore.
4363 @section @code{.cfi_same_value @var{register}}
4364 Current value of @var{register} is the same like in the previous frame,
4365 i.e. no restoration needed.
4367 @section @code{.cfi_remember_state},
4368 First save all current rules for all registers by @code{.cfi_remember_state},
4369 then totally screw them up by subsequent @code{.cfi_*} directives and when
4370 everything is hopelessly bad, use @code{.cfi_restore_state} to restore
4371 the previous saved state.
4373 @section @code{.cfi_return_column @var{register}}
4374 Change return column @var{register}, i.e. the return address is either
4375 directly in @var{register} or can be accessed by rules for @var{register}.
4377 @section @code{.cfi_signal_frame}
4378 Mark current function as signal trampoline.
4380 @section @code{.cfi_window_save}
4381 SPARC register window has been saved.
4383 @section @code{.cfi_escape} @var{expression}[, @dots{}]
4384 Allows the user to add arbitrary bytes to the unwind info. One
4385 might use this to add OS-specific CFI opcodes, or generic CFI
4386 opcodes that GAS does not yet support.
4388 @section @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}}
4389 The current value of @var{register} is @var{label}. The value of @var{label}
4390 will be encoded in the output file according to @var{encoding}; see the
4391 description of @code{.cfi_personality} for details on this encoding.
4393 The usefulness of equating a register to a fixed label is probably
4394 limited to the return address register. Here, it can be useful to
4395 mark a code segment that has only one return address which is reached
4396 by a direct branch and no copy of the return address exists in memory
4397 or another register.
4400 @section @code{.comm @var{symbol} , @var{length} }
4402 @cindex @code{comm} directive
4403 @cindex symbol, common
4404 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
4405 common symbol in one object file may be merged with a defined or common symbol
4406 of the same name in another object file. If @code{@value{LD}} does not see a
4407 definition for the symbol--just one or more common symbols--then it will
4408 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
4409 absolute expression. If @code{@value{LD}} sees multiple common symbols with
4410 the same name, and they do not all have the same size, it will allocate space
4411 using the largest size.
4414 When using ELF or (as a GNU extension) PE, the @code{.comm} directive takes
4415 an optional third argument. This is the desired alignment of the symbol,
4416 specified for ELF as a byte boundary (for example, an alignment of 16 means
4417 that the least significant 4 bits of the address should be zero), and for PE
4418 as a power of two (for example, an alignment of 5 means aligned to a 32-byte
4419 boundary). The alignment must be an absolute expression, and it must be a
4420 power of two. If @code{@value{LD}} allocates uninitialized memory for the
4421 common symbol, it will use the alignment when placing the symbol. If no
4422 alignment is specified, @command{@value{AS}} will set the alignment to the
4423 largest power of two less than or equal to the size of the symbol, up to a
4424 maximum of 16 on ELF, or the default section alignment of 4 on PE@footnote{This
4425 is not the same as the executable image file alignment controlled by @code{@value{LD}}'s
4426 @samp{--section-alignment} option; image file sections in PE are aligned to
4427 multiples of 4096, which is far too large an alignment for ordinary variables.
4428 It is rather the default alignment for (non-debug) sections within object
4429 (@samp{*.o}) files, which are less strictly aligned.}.
4433 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4434 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4438 @section @code{.data @var{subsection}}
4440 @cindex @code{data} directive
4441 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4442 end of the data subsection numbered @var{subsection} (which is an
4443 absolute expression). If @var{subsection} is omitted, it defaults
4448 @section @code{.def @var{name}}
4450 @cindex @code{def} directive
4451 @cindex COFF symbols, debugging
4452 @cindex debugging COFF symbols
4453 Begin defining debugging information for a symbol @var{name}; the
4454 definition extends until the @code{.endef} directive is encountered.
4457 This directive is only observed when @command{@value{AS}} is configured for COFF
4458 format output; when producing @code{b.out}, @samp{.def} is recognized,
4465 @section @code{.desc @var{symbol}, @var{abs-expression}}
4467 @cindex @code{desc} directive
4468 @cindex COFF symbol descriptor
4469 @cindex symbol descriptor, COFF
4470 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4471 to the low 16 bits of an absolute expression.
4474 The @samp{.desc} directive is not available when @command{@value{AS}} is
4475 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4476 object format. For the sake of compatibility, @command{@value{AS}} accepts
4477 it, but produces no output, when configured for COFF.
4483 @section @code{.dim}
4485 @cindex @code{dim} directive
4486 @cindex COFF auxiliary symbol information
4487 @cindex auxiliary symbol information, COFF
4488 This directive is generated by compilers to include auxiliary debugging
4489 information in the symbol table. It is only permitted inside
4490 @code{.def}/@code{.endef} pairs.
4493 @samp{.dim} is only meaningful when generating COFF format output; when
4494 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4500 @section @code{.double @var{flonums}}
4502 @cindex @code{double} directive
4503 @cindex floating point numbers (double)
4504 @code{.double} expects zero or more flonums, separated by commas. It
4505 assembles floating point numbers.
4507 The exact kind of floating point numbers emitted depends on how
4508 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4512 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4513 in @sc{ieee} format.
4518 @section @code{.eject}
4520 @cindex @code{eject} directive
4521 @cindex new page, in listings
4522 @cindex page, in listings
4523 @cindex listing control: new page
4524 Force a page break at this point, when generating assembly listings.
4527 @section @code{.else}
4529 @cindex @code{else} directive
4530 @code{.else} is part of the @command{@value{AS}} support for conditional
4531 assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section
4532 of code to be assembled if the condition for the preceding @code{.if}
4536 @section @code{.elseif}
4538 @cindex @code{elseif} directive
4539 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4540 assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new
4541 @code{.if} block that would otherwise fill the entire @code{.else} section.
4544 @section @code{.end}
4546 @cindex @code{end} directive
4547 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4548 process anything in the file past the @code{.end} directive.
4552 @section @code{.endef}
4554 @cindex @code{endef} directive
4555 This directive flags the end of a symbol definition begun with
4559 @samp{.endef} is only meaningful when generating COFF format output; if
4560 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4561 directive but ignores it.
4566 @section @code{.endfunc}
4567 @cindex @code{endfunc} directive
4568 @code{.endfunc} marks the end of a function specified with @code{.func}.
4571 @section @code{.endif}
4573 @cindex @code{endif} directive
4574 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4575 it marks the end of a block of code that is only assembled
4576 conditionally. @xref{If,,@code{.if}}.
4579 @section @code{.equ @var{symbol}, @var{expression}}
4581 @cindex @code{equ} directive
4582 @cindex assigning values to symbols
4583 @cindex symbols, assigning values to
4584 This directive sets the value of @var{symbol} to @var{expression}.
4585 It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}.
4588 The syntax for @code{equ} on the HPPA is
4589 @samp{@var{symbol} .equ @var{expression}}.
4593 The syntax for @code{equ} on the Z80 is
4594 @samp{@var{symbol} equ @var{expression}}.
4595 On the Z80 it is an eror if @var{symbol} is already defined,
4596 but the symbol is not protected from later redefinition.
4597 Compare @ref{Equiv}.
4601 @section @code{.equiv @var{symbol}, @var{expression}}
4602 @cindex @code{equiv} directive
4603 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4604 the assembler will signal an error if @var{symbol} is already defined. Note a
4605 symbol which has been referenced but not actually defined is considered to be
4608 Except for the contents of the error message, this is roughly equivalent to
4615 plus it protects the symbol from later redefinition.
4618 @section @code{.eqv @var{symbol}, @var{expression}}
4619 @cindex @code{eqv} directive
4620 The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to
4621 evaluate the expression or any part of it immediately. Instead each time
4622 the resulting symbol is used in an expression, a snapshot of its current
4626 @section @code{.err}
4627 @cindex @code{err} directive
4628 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4629 message and, unless the @option{-Z} option was used, it will not generate an
4630 object file. This can be used to signal an error in conditionally compiled code.
4633 @section @code{.error "@var{string}"}
4634 @cindex error directive
4636 Similarly to @code{.err}, this directive emits an error, but you can specify a
4637 string that will be emitted as the error message. If you don't specify the
4638 message, it defaults to @code{".error directive invoked in source file"}.
4639 @xref{Errors, ,Error and Warning Messages}.
4642 .error "This code has not been assembled and tested."
4646 @section @code{.exitm}
4647 Exit early from the current macro definition. @xref{Macro}.
4650 @section @code{.extern}
4652 @cindex @code{extern} directive
4653 @code{.extern} is accepted in the source program---for compatibility
4654 with other assemblers---but it is ignored. @command{@value{AS}} treats
4655 all undefined symbols as external.
4658 @section @code{.fail @var{expression}}
4660 @cindex @code{fail} directive
4661 Generates an error or a warning. If the value of the @var{expression} is 500
4662 or more, @command{@value{AS}} will print a warning message. If the value is less
4663 than 500, @command{@value{AS}} will print an error message. The message will
4664 include the value of @var{expression}. This can occasionally be useful inside
4665 complex nested macros or conditional assembly.
4668 @section @code{.file}
4669 @cindex @code{file} directive
4671 @ifclear no-file-dir
4672 There are two different versions of the @code{.file} directive. Targets
4673 that support DWARF2 line number information use the DWARF2 version of
4674 @code{.file}. Other targets use the default version.
4676 @subheading Default Version
4678 @cindex logical file name
4679 @cindex file name, logical
4680 This version of the @code{.file} directive tells @command{@value{AS}} that we
4681 are about to start a new logical file. The syntax is:
4687 @var{string} is the new file name. In general, the filename is
4688 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4689 to specify an empty file name, you must give the quotes--@code{""}. This
4690 statement may go away in future: it is only recognized to be compatible with
4691 old @command{@value{AS}} programs.
4693 @subheading DWARF2 Version
4696 When emitting DWARF2 line number information, @code{.file} assigns filenames
4697 to the @code{.debug_line} file name table. The syntax is:
4700 .file @var{fileno} @var{filename}
4703 The @var{fileno} operand should be a unique positive integer to use as the
4704 index of the entry in the table. The @var{filename} operand is a C string
4707 The detail of filename indices is exposed to the user because the filename
4708 table is shared with the @code{.debug_info} section of the DWARF2 debugging
4709 information, and thus the user must know the exact indices that table
4713 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4715 @cindex @code{fill} directive
4716 @cindex writing patterns in memory
4717 @cindex patterns, writing in memory
4718 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4719 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4720 may be zero or more. @var{Size} may be zero or more, but if it is
4721 more than 8, then it is deemed to have the value 8, compatible with
4722 other people's assemblers. The contents of each @var{repeat} bytes
4723 is taken from an 8-byte number. The highest order 4 bytes are
4724 zero. The lowest order 4 bytes are @var{value} rendered in the
4725 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4726 Each @var{size} bytes in a repetition is taken from the lowest order
4727 @var{size} bytes of this number. Again, this bizarre behavior is
4728 compatible with other people's assemblers.
4730 @var{size} and @var{value} are optional.
4731 If the second comma and @var{value} are absent, @var{value} is
4732 assumed zero. If the first comma and following tokens are absent,
4733 @var{size} is assumed to be 1.
4736 @section @code{.float @var{flonums}}
4738 @cindex floating point numbers (single)
4739 @cindex @code{float} directive
4740 This directive assembles zero or more flonums, separated by commas. It
4741 has the same effect as @code{.single}.
4743 The exact kind of floating point numbers emitted depends on how
4744 @command{@value{AS}} is configured.
4745 @xref{Machine Dependencies}.
4749 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4750 in @sc{ieee} format.
4755 @section @code{.func @var{name}[,@var{label}]}
4756 @cindex @code{func} directive
4757 @code{.func} emits debugging information to denote function @var{name}, and
4758 is ignored unless the file is assembled with debugging enabled.
4759 Only @samp{--gstabs[+]} is currently supported.
4760 @var{label} is the entry point of the function and if omitted @var{name}
4761 prepended with the @samp{leading char} is used.
4762 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4763 All functions are currently defined to have @code{void} return type.
4764 The function must be terminated with @code{.endfunc}.
4767 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4769 @cindex @code{global} directive
4770 @cindex symbol, making visible to linker
4771 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4772 @var{symbol} in your partial program, its value is made available to
4773 other partial programs that are linked with it. Otherwise,
4774 @var{symbol} takes its attributes from a symbol of the same name
4775 from another file linked into the same program.
4777 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4778 compatibility with other assemblers.
4781 On the HPPA, @code{.global} is not always enough to make it accessible to other
4782 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4783 @xref{HPPA Directives, ,HPPA Assembler Directives}.
4788 @section @code{.gnu_attribute @var{tag},@var{value}}
4789 Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
4792 @section @code{.hidden @var{names}}
4794 @cindex @code{hidden} directive
4796 This is one of the ELF visibility directives. The other two are
4797 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4798 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4800 This directive overrides the named symbols default visibility (which is set by
4801 their binding: local, global or weak). The directive sets the visibility to
4802 @code{hidden} which means that the symbols are not visible to other components.
4803 Such symbols are always considered to be @code{protected} as well.
4807 @section @code{.hword @var{expressions}}
4809 @cindex @code{hword} directive
4810 @cindex integers, 16-bit
4811 @cindex numbers, 16-bit
4812 @cindex sixteen bit integers
4813 This expects zero or more @var{expressions}, and emits
4814 a 16 bit number for each.
4817 This directive is a synonym for @samp{.short}; depending on the target
4818 architecture, it may also be a synonym for @samp{.word}.
4822 This directive is a synonym for @samp{.short}.
4825 This directive is a synonym for both @samp{.short} and @samp{.word}.
4830 @section @code{.ident}
4832 @cindex @code{ident} directive
4834 This directive is used by some assemblers to place tags in object files. The
4835 behavior of this directive varies depending on the target. When using the
4836 a.out object file format, @command{@value{AS}} simply accepts the directive for
4837 source-file compatibility with existing assemblers, but does not emit anything
4838 for it. When using COFF, comments are emitted to the @code{.comment} or
4839 @code{.rdata} section, depending on the target. When using ELF, comments are
4840 emitted to the @code{.comment} section.
4843 @section @code{.if @var{absolute expression}}
4845 @cindex conditional assembly
4846 @cindex @code{if} directive
4847 @code{.if} marks the beginning of a section of code which is only
4848 considered part of the source program being assembled if the argument
4849 (which must be an @var{absolute expression}) is non-zero. The end of
4850 the conditional section of code must be marked by @code{.endif}
4851 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4852 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4853 If you have several conditions to check, @code{.elseif} may be used to avoid
4854 nesting blocks if/else within each subsequent @code{.else} block.
4856 The following variants of @code{.if} are also supported:
4858 @cindex @code{ifdef} directive
4859 @item .ifdef @var{symbol}
4860 Assembles the following section of code if the specified @var{symbol}
4861 has been defined. Note a symbol which has been referenced but not yet defined
4862 is considered to be undefined.
4864 @cindex @code{ifb} directive
4865 @item .ifb @var{text}
4866 Assembles the following section of code if the operand is blank (empty).
4868 @cindex @code{ifc} directive
4869 @item .ifc @var{string1},@var{string2}
4870 Assembles the following section of code if the two strings are the same. The
4871 strings may be optionally quoted with single quotes. If they are not quoted,
4872 the first string stops at the first comma, and the second string stops at the
4873 end of the line. Strings which contain whitespace should be quoted. The
4874 string comparison is case sensitive.
4876 @cindex @code{ifeq} directive
4877 @item .ifeq @var{absolute expression}
4878 Assembles the following section of code if the argument is zero.
4880 @cindex @code{ifeqs} directive
4881 @item .ifeqs @var{string1},@var{string2}
4882 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4884 @cindex @code{ifge} directive
4885 @item .ifge @var{absolute expression}
4886 Assembles the following section of code if the argument is greater than or
4889 @cindex @code{ifgt} directive
4890 @item .ifgt @var{absolute expression}
4891 Assembles the following section of code if the argument is greater than zero.
4893 @cindex @code{ifle} directive
4894 @item .ifle @var{absolute expression}
4895 Assembles the following section of code if the argument is less than or equal
4898 @cindex @code{iflt} directive
4899 @item .iflt @var{absolute expression}
4900 Assembles the following section of code if the argument is less than zero.
4902 @cindex @code{ifnb} directive
4903 @item .ifnb @var{text}
4904 Like @code{.ifb}, but the sense of the test is reversed: this assembles the
4905 following section of code if the operand is non-blank (non-empty).
4907 @cindex @code{ifnc} directive
4908 @item .ifnc @var{string1},@var{string2}.
4909 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4910 following section of code if the two strings are not the same.
4912 @cindex @code{ifndef} directive
4913 @cindex @code{ifnotdef} directive
4914 @item .ifndef @var{symbol}
4915 @itemx .ifnotdef @var{symbol}
4916 Assembles the following section of code if the specified @var{symbol}
4917 has not been defined. Both spelling variants are equivalent. Note a symbol
4918 which has been referenced but not yet defined is considered to be undefined.
4920 @cindex @code{ifne} directive
4921 @item .ifne @var{absolute expression}
4922 Assembles the following section of code if the argument is not equal to zero
4923 (in other words, this is equivalent to @code{.if}).
4925 @cindex @code{ifnes} directive
4926 @item .ifnes @var{string1},@var{string2}
4927 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4928 following section of code if the two strings are not the same.
4932 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4934 @cindex @code{incbin} directive
4935 @cindex binary files, including
4936 The @code{incbin} directive includes @var{file} verbatim at the current
4937 location. You can control the search paths used with the @samp{-I} command-line
4938 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4941 The @var{skip} argument skips a number of bytes from the start of the
4942 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4943 read. Note that the data is not aligned in any way, so it is the user's
4944 responsibility to make sure that proper alignment is provided both before and
4945 after the @code{incbin} directive.
4948 @section @code{.include "@var{file}"}
4950 @cindex @code{include} directive
4951 @cindex supporting files, including
4952 @cindex files, including
4953 This directive provides a way to include supporting files at specified
4954 points in your source program. The code from @var{file} is assembled as
4955 if it followed the point of the @code{.include}; when the end of the
4956 included file is reached, assembly of the original file continues. You
4957 can control the search paths used with the @samp{-I} command-line option
4958 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4962 @section @code{.int @var{expressions}}
4964 @cindex @code{int} directive
4965 @cindex integers, 32-bit
4966 Expect zero or more @var{expressions}, of any section, separated by commas.
4967 For each expression, emit a number that, at run time, is the value of that
4968 expression. The byte order and bit size of the number depends on what kind
4969 of target the assembly is for.
4973 On most forms of the H8/300, @code{.int} emits 16-bit
4974 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
4981 @section @code{.internal @var{names}}
4983 @cindex @code{internal} directive
4985 This is one of the ELF visibility directives. The other two are
4986 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4987 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4989 This directive overrides the named symbols default visibility (which is set by
4990 their binding: local, global or weak). The directive sets the visibility to
4991 @code{internal} which means that the symbols are considered to be @code{hidden}
4992 (i.e., not visible to other components), and that some extra, processor specific
4993 processing must also be performed upon the symbols as well.
4997 @section @code{.irp @var{symbol},@var{values}}@dots{}
4999 @cindex @code{irp} directive
5000 Evaluate a sequence of statements assigning different values to @var{symbol}.
5001 The sequence of statements starts at the @code{.irp} directive, and is
5002 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
5003 set to @var{value}, and the sequence of statements is assembled. If no
5004 @var{value} is listed, the sequence of statements is assembled once, with
5005 @var{symbol} set to the null string. To refer to @var{symbol} within the
5006 sequence of statements, use @var{\symbol}.
5008 For example, assembling
5016 is equivalent to assembling
5024 For some caveats with the spelling of @var{symbol}, see also @ref{Macro}.
5027 @section @code{.irpc @var{symbol},@var{values}}@dots{}
5029 @cindex @code{irpc} directive
5030 Evaluate a sequence of statements assigning different values to @var{symbol}.
5031 The sequence of statements starts at the @code{.irpc} directive, and is
5032 terminated by an @code{.endr} directive. For each character in @var{value},
5033 @var{symbol} is set to the character, and the sequence of statements is
5034 assembled. If no @var{value} is listed, the sequence of statements is
5035 assembled once, with @var{symbol} set to the null string. To refer to
5036 @var{symbol} within the sequence of statements, use @var{\symbol}.
5038 For example, assembling
5046 is equivalent to assembling
5054 For some caveats with the spelling of @var{symbol}, see also the discussion
5058 @section @code{.lcomm @var{symbol} , @var{length}}
5060 @cindex @code{lcomm} directive
5061 @cindex local common symbols
5062 @cindex symbols, local common
5063 Reserve @var{length} (an absolute expression) bytes for a local common
5064 denoted by @var{symbol}. The section and value of @var{symbol} are
5065 those of the new local common. The addresses are allocated in the bss
5066 section, so that at run-time the bytes start off zeroed. @var{Symbol}
5067 is not declared global (@pxref{Global,,@code{.global}}), so is normally
5068 not visible to @code{@value{LD}}.
5071 Some targets permit a third argument to be used with @code{.lcomm}. This
5072 argument specifies the desired alignment of the symbol in the bss section.
5076 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
5077 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
5081 @section @code{.lflags}
5083 @cindex @code{lflags} directive (ignored)
5084 @command{@value{AS}} accepts this directive, for compatibility with other
5085 assemblers, but ignores it.
5087 @ifclear no-line-dir
5089 @section @code{.line @var{line-number}}
5091 @cindex @code{line} directive
5092 @cindex logical line number
5094 Change the logical line number. @var{line-number} must be an absolute
5095 expression. The next line has that logical line number. Therefore any other
5096 statements on the current line (after a statement separator character) are
5097 reported as on logical line number @var{line-number} @minus{} 1. One day
5098 @command{@value{AS}} will no longer support this directive: it is recognized only
5099 for compatibility with existing assembler programs.
5102 Even though this is a directive associated with the @code{a.out} or
5103 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
5104 when producing COFF output, and treats @samp{.line} as though it
5105 were the COFF @samp{.ln} @emph{if} it is found outside a
5106 @code{.def}/@code{.endef} pair.
5108 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
5109 used by compilers to generate auxiliary symbol information for
5114 @section @code{.linkonce [@var{type}]}
5116 @cindex @code{linkonce} directive
5117 @cindex common sections
5118 Mark the current section so that the linker only includes a single copy of it.
5119 This may be used to include the same section in several different object files,
5120 but ensure that the linker will only include it once in the final output file.
5121 The @code{.linkonce} pseudo-op must be used for each instance of the section.
5122 Duplicate sections are detected based on the section name, so it should be
5125 This directive is only supported by a few object file formats; as of this
5126 writing, the only object file format which supports it is the Portable
5127 Executable format used on Windows NT.
5129 The @var{type} argument is optional. If specified, it must be one of the
5130 following strings. For example:
5134 Not all types may be supported on all object file formats.
5138 Silently discard duplicate sections. This is the default.
5141 Warn if there are duplicate sections, but still keep only one copy.
5144 Warn if any of the duplicates have different sizes.
5147 Warn if any of the duplicates do not have exactly the same contents.
5151 @section @code{.list}
5153 @cindex @code{list} directive
5154 @cindex listing control, turning on
5155 Control (in conjunction with the @code{.nolist} directive) whether or
5156 not assembly listings are generated. These two directives maintain an
5157 internal counter (which is zero initially). @code{.list} increments the
5158 counter, and @code{.nolist} decrements it. Assembly listings are
5159 generated whenever the counter is greater than zero.
5161 By default, listings are disabled. When you enable them (with the
5162 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
5163 the initial value of the listing counter is one.
5166 @section @code{.ln @var{line-number}}
5168 @cindex @code{ln} directive
5169 @ifclear no-line-dir
5170 @samp{.ln} is a synonym for @samp{.line}.
5173 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
5174 must be an absolute expression. The next line has that logical
5175 line number, so any other statements on the current line (after a
5176 statement separator character @code{;}) are reported as on logical
5177 line number @var{line-number} @minus{} 1.
5180 This directive is accepted, but ignored, when @command{@value{AS}} is
5181 configured for @code{b.out}; its effect is only associated with COFF
5187 @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]}
5188 @cindex @code{loc} directive
5189 When emitting DWARF2 line number information,
5190 the @code{.loc} directive will add a row to the @code{.debug_line} line
5191 number matrix corresponding to the immediately following assembly
5192 instruction. The @var{fileno}, @var{lineno}, and optional @var{column}
5193 arguments will be applied to the @code{.debug_line} state machine before
5196 The @var{options} are a sequence of the following tokens in any order:
5200 This option will set the @code{basic_block} register in the
5201 @code{.debug_line} state machine to @code{true}.
5204 This option will set the @code{prologue_end} register in the
5205 @code{.debug_line} state machine to @code{true}.
5207 @item epilogue_begin
5208 This option will set the @code{epilogue_begin} register in the
5209 @code{.debug_line} state machine to @code{true}.
5211 @item is_stmt @var{value}
5212 This option will set the @code{is_stmt} register in the
5213 @code{.debug_line} state machine to @code{value}, which must be
5216 @item isa @var{value}
5217 This directive will set the @code{isa} register in the @code{.debug_line}
5218 state machine to @var{value}, which must be an unsigned integer.
5220 @item discriminator @var{value}
5221 This directive will set the @code{discriminator} register in the @code{.debug_line}
5222 state machine to @var{value}, which must be an unsigned integer.
5226 @node Loc_mark_labels
5227 @section @code{.loc_mark_labels @var{enable}}
5228 @cindex @code{loc_mark_labels} directive
5229 When emitting DWARF2 line number information,
5230 the @code{.loc_mark_labels} directive makes the assembler emit an entry
5231 to the @code{.debug_line} line number matrix with the @code{basic_block}
5232 register in the state machine set whenever a code label is seen.
5233 The @var{enable} argument should be either 1 or 0, to enable or disable
5234 this function respectively.
5238 @section @code{.local @var{names}}
5240 @cindex @code{local} directive
5241 This directive, which is available for ELF targets, marks each symbol in
5242 the comma-separated list of @code{names} as a local symbol so that it
5243 will not be externally visible. If the symbols do not already exist,
5244 they will be created.
5246 For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not
5247 accept an alignment argument, which is the case for most ELF targets,
5248 the @code{.local} directive can be used in combination with @code{.comm}
5249 (@pxref{Comm}) to define aligned local common data.
5253 @section @code{.long @var{expressions}}
5255 @cindex @code{long} directive
5256 @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}.
5259 @c no one seems to know what this is for or whether this description is
5260 @c what it really ought to do
5262 @section @code{.lsym @var{symbol}, @var{expression}}
5264 @cindex @code{lsym} directive
5265 @cindex symbol, not referenced in assembly
5266 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
5267 the hash table, ensuring it cannot be referenced by name during the
5268 rest of the assembly. This sets the attributes of the symbol to be
5269 the same as the expression value:
5271 @var{other} = @var{descriptor} = 0
5272 @var{type} = @r{(section of @var{expression})}
5273 @var{value} = @var{expression}
5276 The new symbol is not flagged as external.
5280 @section @code{.macro}
5283 The commands @code{.macro} and @code{.endm} allow you to define macros that
5284 generate assembly output. For example, this definition specifies a macro
5285 @code{sum} that puts a sequence of numbers into memory:
5288 .macro sum from=0, to=5
5297 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
5309 @item .macro @var{macname}
5310 @itemx .macro @var{macname} @var{macargs} @dots{}
5311 @cindex @code{macro} directive
5312 Begin the definition of a macro called @var{macname}. If your macro
5313 definition requires arguments, specify their names after the macro name,
5314 separated by commas or spaces. You can qualify the macro argument to
5315 indicate whether all invocations must specify a non-blank value (through
5316 @samp{:@code{req}}), or whether it takes all of the remaining arguments
5317 (through @samp{:@code{vararg}}). You can supply a default value for any
5318 macro argument by following the name with @samp{=@var{deflt}}. You
5319 cannot define two macros with the same @var{macname} unless it has been
5320 subject to the @code{.purgem} directive (@pxref{Purgem}) between the two
5321 definitions. For example, these are all valid @code{.macro} statements:
5325 Begin the definition of a macro called @code{comm}, which takes no
5328 @item .macro plus1 p, p1
5329 @itemx .macro plus1 p p1
5330 Either statement begins the definition of a macro called @code{plus1},
5331 which takes two arguments; within the macro definition, write
5332 @samp{\p} or @samp{\p1} to evaluate the arguments.
5334 @item .macro reserve_str p1=0 p2
5335 Begin the definition of a macro called @code{reserve_str}, with two
5336 arguments. The first argument has a default value, but not the second.
5337 After the definition is complete, you can call the macro either as
5338 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
5339 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
5340 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
5341 @samp{0}, and @samp{\p2} evaluating to @var{b}).
5343 @item .macro m p1:req, p2=0, p3:vararg
5344 Begin the definition of a macro called @code{m}, with at least three
5345 arguments. The first argument must always have a value specified, but
5346 not the second, which instead has a default value. The third formal
5347 will get assigned all remaining arguments specified at invocation time.
5349 When you call a macro, you can specify the argument values either by
5350 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
5351 @samp{sum to=17, from=9}.
5355 Note that since each of the @var{macargs} can be an identifier exactly
5356 as any other one permitted by the target architecture, there may be
5357 occasional problems if the target hand-crafts special meanings to certain
5358 characters when they occur in a special position. For example, if the colon
5359 (@code{:}) is generally permitted to be part of a symbol name, but the
5360 architecture specific code special-cases it when occurring as the final
5361 character of a symbol (to denote a label), then the macro parameter
5362 replacement code will have no way of knowing that and consider the whole
5363 construct (including the colon) an identifier, and check only this
5364 identifier for being the subject to parameter substitution. So for example
5365 this macro definition:
5373 might not work as expected. Invoking @samp{label foo} might not create a label
5374 called @samp{foo} but instead just insert the text @samp{\l:} into the
5375 assembler source, probably generating an error about an unrecognised
5378 Similarly problems might occur with the period character (@samp{.})
5379 which is often allowed inside opcode names (and hence identifier names). So
5380 for example constructing a macro to build an opcode from a base name and a
5381 length specifier like this:
5384 .macro opcode base length
5389 and invoking it as @samp{opcode store l} will not create a @samp{store.l}
5390 instruction but instead generate some kind of error as the assembler tries to
5391 interpret the text @samp{\base.\length}.
5393 There are several possible ways around this problem:
5396 @item Insert white space
5397 If it is possible to use white space characters then this is the simplest
5406 @item Use @samp{\()}
5407 The string @samp{\()} can be used to separate the end of a macro argument from
5408 the following text. eg:
5411 .macro opcode base length
5416 @item Use the alternate macro syntax mode
5417 In the alternative macro syntax mode the ampersand character (@samp{&}) can be
5418 used as a separator. eg:
5428 Note: this problem of correctly identifying string parameters to pseudo ops
5429 also applies to the identifiers used in @code{.irp} (@pxref{Irp})
5430 and @code{.irpc} (@pxref{Irpc}) as well.
5433 @cindex @code{endm} directive
5434 Mark the end of a macro definition.
5437 @cindex @code{exitm} directive
5438 Exit early from the current macro definition.
5440 @cindex number of macros executed
5441 @cindex macros, count executed
5443 @command{@value{AS}} maintains a counter of how many macros it has
5444 executed in this pseudo-variable; you can copy that number to your
5445 output with @samp{\@@}, but @emph{only within a macro definition}.
5447 @item LOCAL @var{name} [ , @dots{} ]
5448 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
5449 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
5450 @xref{Altmacro,,@code{.altmacro}}.
5454 @section @code{.mri @var{val}}
5456 @cindex @code{mri} directive
5457 @cindex MRI mode, temporarily
5458 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
5459 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
5460 affects code assembled until the next @code{.mri} directive, or until the end
5461 of the file. @xref{M, MRI mode, MRI mode}.
5464 @section @code{.noaltmacro}
5465 Disable alternate macro mode. @xref{Altmacro}.
5468 @section @code{.nolist}
5470 @cindex @code{nolist} directive
5471 @cindex listing control, turning off
5472 Control (in conjunction with the @code{.list} directive) whether or
5473 not assembly listings are generated. These two directives maintain an
5474 internal counter (which is zero initially). @code{.list} increments the
5475 counter, and @code{.nolist} decrements it. Assembly listings are
5476 generated whenever the counter is greater than zero.
5479 @section @code{.octa @var{bignums}}
5481 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
5482 @cindex @code{octa} directive
5483 @cindex integer, 16-byte
5484 @cindex sixteen byte integer
5485 This directive expects zero or more bignums, separated by commas. For each
5486 bignum, it emits a 16-byte integer.
5488 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
5489 hence @emph{octa}-word for 16 bytes.
5492 @section @code{.org @var{new-lc} , @var{fill}}
5494 @cindex @code{org} directive
5495 @cindex location counter, advancing
5496 @cindex advancing location counter
5497 @cindex current address, advancing
5498 Advance the location counter of the current section to
5499 @var{new-lc}. @var{new-lc} is either an absolute expression or an
5500 expression with the same section as the current subsection. That is,
5501 you can't use @code{.org} to cross sections: if @var{new-lc} has the
5502 wrong section, the @code{.org} directive is ignored. To be compatible
5503 with former assemblers, if the section of @var{new-lc} is absolute,
5504 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
5505 is the same as the current subsection.
5507 @code{.org} may only increase the location counter, or leave it
5508 unchanged; you cannot use @code{.org} to move the location counter
5511 @c double negative used below "not undefined" because this is a specific
5512 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
5513 @c section. doc@cygnus.com 18feb91
5514 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
5515 may not be undefined. If you really detest this restriction we eagerly await
5516 a chance to share your improved assembler.
5518 Beware that the origin is relative to the start of the section, not
5519 to the start of the subsection. This is compatible with other
5520 people's assemblers.
5522 When the location counter (of the current subsection) is advanced, the
5523 intervening bytes are filled with @var{fill} which should be an
5524 absolute expression. If the comma and @var{fill} are omitted,
5525 @var{fill} defaults to zero.
5528 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
5530 @cindex padding the location counter given a power of two
5531 @cindex @code{p2align} directive
5532 Pad the location counter (in the current subsection) to a particular
5533 storage boundary. The first expression (which must be absolute) is the
5534 number of low-order zero bits the location counter must have after
5535 advancement. For example @samp{.p2align 3} advances the location
5536 counter until it a multiple of 8. If the location counter is already a
5537 multiple of 8, no change is needed.
5539 The second expression (also absolute) gives the fill value to be stored in the
5540 padding bytes. It (and the comma) may be omitted. If it is omitted, the
5541 padding bytes are normally zero. However, on some systems, if the section is
5542 marked as containing code and the fill value is omitted, the space is filled
5543 with no-op instructions.
5545 The third expression is also absolute, and is also optional. If it is present,
5546 it is the maximum number of bytes that should be skipped by this alignment
5547 directive. If doing the alignment would require skipping more bytes than the
5548 specified maximum, then the alignment is not done at all. You can omit the
5549 fill value (the second argument) entirely by simply using two commas after the
5550 required alignment; this can be useful if you want the alignment to be filled
5551 with no-op instructions when appropriate.
5553 @cindex @code{p2alignw} directive
5554 @cindex @code{p2alignl} directive
5555 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5556 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5557 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5558 fill pattern as a four byte longword value. For example, @code{.p2alignw
5559 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5560 filled in with the value 0x368d (the exact placement of the bytes depends upon
5561 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5566 @section @code{.popsection}
5568 @cindex @code{popsection} directive
5569 @cindex Section Stack
5570 This is one of the ELF section stack manipulation directives. The others are
5571 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5572 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5575 This directive replaces the current section (and subsection) with the top
5576 section (and subsection) on the section stack. This section is popped off the
5582 @section @code{.previous}
5584 @cindex @code{previous} directive
5585 @cindex Section Stack
5586 This is one of the ELF section stack manipulation directives. The others are
5587 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5588 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5589 (@pxref{PopSection}).
5591 This directive swaps the current section (and subsection) with most recently
5592 referenced section/subsection pair prior to this one. Multiple
5593 @code{.previous} directives in a row will flip between two sections (and their
5594 subsections). For example:
5606 Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
5612 # Now in section A subsection 1
5616 # Now in section B subsection 0
5619 # Now in section B subsection 1
5622 # Now in section B subsection 0
5626 Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
5627 section B and 0x9abc into subsection 1 of section B.
5629 In terms of the section stack, this directive swaps the current section with
5630 the top section on the section stack.
5634 @section @code{.print @var{string}}
5636 @cindex @code{print} directive
5637 @command{@value{AS}} will print @var{string} on the standard output during
5638 assembly. You must put @var{string} in double quotes.
5642 @section @code{.protected @var{names}}
5644 @cindex @code{protected} directive
5646 This is one of the ELF visibility directives. The other two are
5647 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
5649 This directive overrides the named symbols default visibility (which is set by
5650 their binding: local, global or weak). The directive sets the visibility to
5651 @code{protected} which means that any references to the symbols from within the
5652 components that defines them must be resolved to the definition in that
5653 component, even if a definition in another component would normally preempt
5658 @section @code{.psize @var{lines} , @var{columns}}
5660 @cindex @code{psize} directive
5661 @cindex listing control: paper size
5662 @cindex paper size, for listings
5663 Use this directive to declare the number of lines---and, optionally, the
5664 number of columns---to use for each page, when generating listings.
5666 If you do not use @code{.psize}, listings use a default line-count
5667 of 60. You may omit the comma and @var{columns} specification; the
5668 default width is 200 columns.
5670 @command{@value{AS}} generates formfeeds whenever the specified number of
5671 lines is exceeded (or whenever you explicitly request one, using
5674 If you specify @var{lines} as @code{0}, no formfeeds are generated save
5675 those explicitly specified with @code{.eject}.
5678 @section @code{.purgem @var{name}}
5680 @cindex @code{purgem} directive
5681 Undefine the macro @var{name}, so that later uses of the string will not be
5682 expanded. @xref{Macro}.
5686 @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]}
5688 @cindex @code{pushsection} directive
5689 @cindex Section Stack
5690 This is one of the ELF section stack manipulation directives. The others are
5691 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5692 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5695 This directive pushes the current section (and subsection) onto the
5696 top of the section stack, and then replaces the current section and
5697 subsection with @code{name} and @code{subsection}. The optional
5698 @code{flags}, @code{type} and @code{arguments} are treated the same
5699 as in the @code{.section} (@pxref{Section}) directive.
5703 @section @code{.quad @var{bignums}}
5705 @cindex @code{quad} directive
5706 @code{.quad} expects zero or more bignums, separated by commas. For
5707 each bignum, it emits
5709 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
5710 warning message; and just takes the lowest order 8 bytes of the bignum.
5711 @cindex eight-byte integer
5712 @cindex integer, 8-byte
5714 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
5715 hence @emph{quad}-word for 8 bytes.
5718 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
5719 warning message; and just takes the lowest order 16 bytes of the bignum.
5720 @cindex sixteen-byte integer
5721 @cindex integer, 16-byte
5725 @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
5727 @cindex @code{reloc} directive
5728 Generate a relocation at @var{offset} of type @var{reloc_name} with value
5729 @var{expression}. If @var{offset} is a number, the relocation is generated in
5730 the current section. If @var{offset} is an expression that resolves to a
5731 symbol plus offset, the relocation is generated in the given symbol's section.
5732 @var{expression}, if present, must resolve to a symbol plus addend or to an
5733 absolute value, but note that not all targets support an addend. e.g. ELF REL
5734 targets such as i386 store an addend in the section contents rather than in the
5735 relocation. This low level interface does not support addends stored in the
5739 @section @code{.rept @var{count}}
5741 @cindex @code{rept} directive
5742 Repeat the sequence of lines between the @code{.rept} directive and the next
5743 @code{.endr} directive @var{count} times.
5745 For example, assembling
5753 is equivalent to assembling
5762 @section @code{.sbttl "@var{subheading}"}
5764 @cindex @code{sbttl} directive
5765 @cindex subtitles for listings
5766 @cindex listing control: subtitle
5767 Use @var{subheading} as the title (third line, immediately after the
5768 title line) when generating assembly listings.
5770 This directive affects subsequent pages, as well as the current page if
5771 it appears within ten lines of the top of a page.
5775 @section @code{.scl @var{class}}
5777 @cindex @code{scl} directive
5778 @cindex symbol storage class (COFF)
5779 @cindex COFF symbol storage class
5780 Set the storage-class value for a symbol. This directive may only be
5781 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
5782 whether a symbol is static or external, or it may record further
5783 symbolic debugging information.
5786 The @samp{.scl} directive is primarily associated with COFF output; when
5787 configured to generate @code{b.out} output format, @command{@value{AS}}
5788 accepts this directive but ignores it.
5794 @section @code{.section @var{name}}
5796 @cindex named section
5797 Use the @code{.section} directive to assemble the following code into a section
5800 This directive is only supported for targets that actually support arbitrarily
5801 named sections; on @code{a.out} targets, for example, it is not accepted, even
5802 with a standard @code{a.out} section name.
5806 @c only print the extra heading if both COFF and ELF are set
5807 @subheading COFF Version
5810 @cindex @code{section} directive (COFF version)
5811 For COFF targets, the @code{.section} directive is used in one of the following
5815 .section @var{name}[, "@var{flags}"]
5816 .section @var{name}[, @var{subsection}]
5819 If the optional argument is quoted, it is taken as flags to use for the
5820 section. Each flag is a single character. The following flags are recognized:
5823 bss section (uninitialized data)
5825 section is not loaded
5835 shared section (meaningful for PE targets)
5837 ignored. (For compatibility with the ELF version)
5839 section is not readable (meaningful for PE targets)
5841 single-digit power-of-two section alignment (GNU extension)
5844 If no flags are specified, the default flags depend upon the section name. If
5845 the section name is not recognized, the default will be for the section to be
5846 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
5847 from the section, rather than adding them, so if they are used on their own it
5848 will be as if no flags had been specified at all.
5850 If the optional argument to the @code{.section} directive is not quoted, it is
5851 taken as a subsection number (@pxref{Sub-Sections}).
5856 @c only print the extra heading if both COFF and ELF are set
5857 @subheading ELF Version
5860 @cindex Section Stack
5861 This is one of the ELF section stack manipulation directives. The others are
5862 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5863 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5864 @code{.previous} (@pxref{Previous}).
5866 @cindex @code{section} directive (ELF version)
5867 For ELF targets, the @code{.section} directive is used like this:
5870 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]]
5873 The optional @var{flags} argument is a quoted string which may contain any
5874 combination of the following characters:
5877 section is allocatable
5879 section is excluded from executable and shared library.
5883 section is executable
5885 section is mergeable
5887 section contains zero terminated strings
5889 section is a member of a section group
5891 section is used for thread-local-storage
5894 The optional @var{type} argument may contain one of the following constants:
5897 section contains data
5899 section does not contain data (i.e., section only occupies space)
5901 section contains data which is used by things other than the program
5903 section contains an array of pointers to init functions
5905 section contains an array of pointers to finish functions
5906 @item @@preinit_array
5907 section contains an array of pointers to pre-init functions
5910 Many targets only support the first three section types.
5912 Note on targets where the @code{@@} character is the start of a comment (eg
5913 ARM) then another character is used instead. For example the ARM port uses the
5916 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
5917 be specified as well as an extra argument---@var{entsize}---like this:
5920 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
5923 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
5924 constants, each @var{entsize} octets long. Sections with both @code{M} and
5925 @code{S} must contain zero terminated strings where each character is
5926 @var{entsize} bytes long. The linker may remove duplicates within sections with
5927 the same name, same entity size and same flags. @var{entsize} must be an
5928 absolute expression. For sections with both @code{M} and @code{S}, a string
5929 which is a suffix of a larger string is considered a duplicate. Thus
5930 @code{"def"} will be merged with @code{"abcdef"}; A reference to the first
5931 @code{"def"} will be changed to a reference to @code{"abcdef"+3}.
5933 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
5934 be present along with an additional field like this:
5937 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
5940 The @var{GroupName} field specifies the name of the section group to which this
5941 particular section belongs. The optional linkage field can contain:
5944 indicates that only one copy of this section should be retained
5949 Note: if both the @var{M} and @var{G} flags are present then the fields for
5950 the Merge flag should come first, like this:
5953 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
5956 If no flags are specified, the default flags depend upon the section name. If
5957 the section name is not recognized, the default will be for the section to have
5958 none of the above flags: it will not be allocated in memory, nor writable, nor
5959 executable. The section will contain data.
5961 For ELF targets, the assembler supports another type of @code{.section}
5962 directive for compatibility with the Solaris assembler:
5965 .section "@var{name}"[, @var{flags}...]
5968 Note that the section name is quoted. There may be a sequence of comma
5972 section is allocatable
5976 section is executable
5978 section is excluded from executable and shared library.
5980 section is used for thread local storage
5983 This directive replaces the current section and subsection. See the
5984 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
5985 some examples of how this directive and the other section stack directives
5991 @section @code{.set @var{symbol}, @var{expression}}
5993 @cindex @code{set} directive
5994 @cindex symbol value, setting
5995 Set the value of @var{symbol} to @var{expression}. This
5996 changes @var{symbol}'s value and type to conform to
5997 @var{expression}. If @var{symbol} was flagged as external, it remains
5998 flagged (@pxref{Symbol Attributes}).
6000 You may @code{.set} a symbol many times in the same assembly.
6002 If you @code{.set} a global symbol, the value stored in the object
6003 file is the last value stored into it.
6006 On Z80 @code{set} is a real instruction, use
6007 @samp{@var{symbol} defl @var{expression}} instead.
6011 @section @code{.short @var{expressions}}
6013 @cindex @code{short} directive
6015 @code{.short} is normally the same as @samp{.word}.
6016 @xref{Word,,@code{.word}}.
6018 In some configurations, however, @code{.short} and @code{.word} generate
6019 numbers of different lengths. @xref{Machine Dependencies}.
6023 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
6026 This expects zero or more @var{expressions}, and emits
6027 a 16 bit number for each.
6032 @section @code{.single @var{flonums}}
6034 @cindex @code{single} directive
6035 @cindex floating point numbers (single)
6036 This directive assembles zero or more flonums, separated by commas. It
6037 has the same effect as @code{.float}.
6039 The exact kind of floating point numbers emitted depends on how
6040 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
6044 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
6045 numbers in @sc{ieee} format.
6051 @section @code{.size}
6053 This directive is used to set the size associated with a symbol.
6057 @c only print the extra heading if both COFF and ELF are set
6058 @subheading COFF Version
6061 @cindex @code{size} directive (COFF version)
6062 For COFF targets, the @code{.size} directive is only permitted inside
6063 @code{.def}/@code{.endef} pairs. It is used like this:
6066 .size @var{expression}
6070 @samp{.size} is only meaningful when generating COFF format output; when
6071 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6078 @c only print the extra heading if both COFF and ELF are set
6079 @subheading ELF Version
6082 @cindex @code{size} directive (ELF version)
6083 For ELF targets, the @code{.size} directive is used like this:
6086 .size @var{name} , @var{expression}
6089 This directive sets the size associated with a symbol @var{name}.
6090 The size in bytes is computed from @var{expression} which can make use of label
6091 arithmetic. This directive is typically used to set the size of function
6096 @ifclear no-space-dir
6098 @section @code{.skip @var{size} , @var{fill}}
6100 @cindex @code{skip} directive
6101 @cindex filling memory
6102 This directive emits @var{size} bytes, each of value @var{fill}. Both
6103 @var{size} and @var{fill} are absolute expressions. If the comma and
6104 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
6109 @section @code{.sleb128 @var{expressions}}
6111 @cindex @code{sleb128} directive
6112 @var{sleb128} stands for ``signed little endian base 128.'' This is a
6113 compact, variable length representation of numbers used by the DWARF
6114 symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}.
6116 @ifclear no-space-dir
6118 @section @code{.space @var{size} , @var{fill}}
6120 @cindex @code{space} directive
6121 @cindex filling memory
6122 This directive emits @var{size} bytes, each of value @var{fill}. Both
6123 @var{size} and @var{fill} are absolute expressions. If the comma
6124 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
6129 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
6130 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
6131 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
6132 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
6140 @section @code{.stabd, .stabn, .stabs}
6142 @cindex symbolic debuggers, information for
6143 @cindex @code{stab@var{x}} directives
6144 There are three directives that begin @samp{.stab}.
6145 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
6146 The symbols are not entered in the @command{@value{AS}} hash table: they
6147 cannot be referenced elsewhere in the source file.
6148 Up to five fields are required:
6152 This is the symbol's name. It may contain any character except
6153 @samp{\000}, so is more general than ordinary symbol names. Some
6154 debuggers used to code arbitrarily complex structures into symbol names
6158 An absolute expression. The symbol's type is set to the low 8 bits of
6159 this expression. Any bit pattern is permitted, but @code{@value{LD}}
6160 and debuggers choke on silly bit patterns.
6163 An absolute expression. The symbol's ``other'' attribute is set to the
6164 low 8 bits of this expression.
6167 An absolute expression. The symbol's descriptor is set to the low 16
6168 bits of this expression.
6171 An absolute expression which becomes the symbol's value.
6174 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
6175 or @code{.stabs} statement, the symbol has probably already been created;
6176 you get a half-formed symbol in your object file. This is
6177 compatible with earlier assemblers!
6180 @cindex @code{stabd} directive
6181 @item .stabd @var{type} , @var{other} , @var{desc}
6183 The ``name'' of the symbol generated is not even an empty string.
6184 It is a null pointer, for compatibility. Older assemblers used a
6185 null pointer so they didn't waste space in object files with empty
6188 The symbol's value is set to the location counter,
6189 relocatably. When your program is linked, the value of this symbol
6190 is the address of the location counter when the @code{.stabd} was
6193 @cindex @code{stabn} directive
6194 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
6195 The name of the symbol is set to the empty string @code{""}.
6197 @cindex @code{stabs} directive
6198 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
6199 All five fields are specified.
6205 @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
6206 "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
6208 @cindex string, copying to object file
6209 @cindex string8, copying to object file
6210 @cindex string16, copying to object file
6211 @cindex string32, copying to object file
6212 @cindex string64, copying to object file
6213 @cindex @code{string} directive
6214 @cindex @code{string8} directive
6215 @cindex @code{string16} directive
6216 @cindex @code{string32} directive
6217 @cindex @code{string64} directive
6219 Copy the characters in @var{str} to the object file. You may specify more than
6220 one string to copy, separated by commas. Unless otherwise specified for a
6221 particular machine, the assembler marks the end of each string with a 0 byte.
6222 You can use any of the escape sequences described in @ref{Strings,,Strings}.
6224 The variants @code{string16}, @code{string32} and @code{string64} differ from
6225 the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
6226 copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
6227 are stored in target endianness byte order.
6233 .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
6234 .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
6239 @section @code{.struct @var{expression}}
6241 @cindex @code{struct} directive
6242 Switch to the absolute section, and set the section offset to @var{expression},
6243 which must be an absolute expression. You might use this as follows:
6252 This would define the symbol @code{field1} to have the value 0, the symbol
6253 @code{field2} to have the value 4, and the symbol @code{field3} to have the
6254 value 8. Assembly would be left in the absolute section, and you would need to
6255 use a @code{.section} directive of some sort to change to some other section
6256 before further assembly.
6260 @section @code{.subsection @var{name}}
6262 @cindex @code{subsection} directive
6263 @cindex Section Stack
6264 This is one of the ELF section stack manipulation directives. The others are
6265 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
6266 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6269 This directive replaces the current subsection with @code{name}. The current
6270 section is not changed. The replaced subsection is put onto the section stack
6271 in place of the then current top of stack subsection.
6276 @section @code{.symver}
6277 @cindex @code{symver} directive
6278 @cindex symbol versioning
6279 @cindex versions of symbols
6280 Use the @code{.symver} directive to bind symbols to specific version nodes
6281 within a source file. This is only supported on ELF platforms, and is
6282 typically used when assembling files to be linked into a shared library.
6283 There are cases where it may make sense to use this in objects to be bound
6284 into an application itself so as to override a versioned symbol from a
6287 For ELF targets, the @code{.symver} directive can be used like this:
6289 .symver @var{name}, @var{name2@@nodename}
6291 If the symbol @var{name} is defined within the file
6292 being assembled, the @code{.symver} directive effectively creates a symbol
6293 alias with the name @var{name2@@nodename}, and in fact the main reason that we
6294 just don't try and create a regular alias is that the @var{@@} character isn't
6295 permitted in symbol names. The @var{name2} part of the name is the actual name
6296 of the symbol by which it will be externally referenced. The name @var{name}
6297 itself is merely a name of convenience that is used so that it is possible to
6298 have definitions for multiple versions of a function within a single source
6299 file, and so that the compiler can unambiguously know which version of a
6300 function is being mentioned. The @var{nodename} portion of the alias should be
6301 the name of a node specified in the version script supplied to the linker when
6302 building a shared library. If you are attempting to override a versioned
6303 symbol from a shared library, then @var{nodename} should correspond to the
6304 nodename of the symbol you are trying to override.
6306 If the symbol @var{name} is not defined within the file being assembled, all
6307 references to @var{name} will be changed to @var{name2@@nodename}. If no
6308 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
6311 Another usage of the @code{.symver} directive is:
6313 .symver @var{name}, @var{name2@@@@nodename}
6315 In this case, the symbol @var{name} must exist and be defined within
6316 the file being assembled. It is similar to @var{name2@@nodename}. The
6317 difference is @var{name2@@@@nodename} will also be used to resolve
6318 references to @var{name2} by the linker.
6320 The third usage of the @code{.symver} directive is:
6322 .symver @var{name}, @var{name2@@@@@@nodename}
6324 When @var{name} is not defined within the
6325 file being assembled, it is treated as @var{name2@@nodename}. When
6326 @var{name} is defined within the file being assembled, the symbol
6327 name, @var{name}, will be changed to @var{name2@@@@nodename}.
6332 @section @code{.tag @var{structname}}
6334 @cindex COFF structure debugging
6335 @cindex structure debugging, COFF
6336 @cindex @code{tag} directive
6337 This directive is generated by compilers to include auxiliary debugging
6338 information in the symbol table. It is only permitted inside
6339 @code{.def}/@code{.endef} pairs. Tags are used to link structure
6340 definitions in the symbol table with instances of those structures.
6343 @samp{.tag} is only used when generating COFF format output; when
6344 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6350 @section @code{.text @var{subsection}}
6352 @cindex @code{text} directive
6353 Tells @command{@value{AS}} to assemble the following statements onto the end of
6354 the text subsection numbered @var{subsection}, which is an absolute
6355 expression. If @var{subsection} is omitted, subsection number zero
6359 @section @code{.title "@var{heading}"}
6361 @cindex @code{title} directive
6362 @cindex listing control: title line
6363 Use @var{heading} as the title (second line, immediately after the
6364 source file name and pagenumber) when generating assembly listings.
6366 This directive affects subsequent pages, as well as the current page if
6367 it appears within ten lines of the top of a page.
6371 @section @code{.type}
6373 This directive is used to set the type of a symbol.
6377 @c only print the extra heading if both COFF and ELF are set
6378 @subheading COFF Version
6381 @cindex COFF symbol type
6382 @cindex symbol type, COFF
6383 @cindex @code{type} directive (COFF version)
6384 For COFF targets, this directive is permitted only within
6385 @code{.def}/@code{.endef} pairs. It is used like this:
6391 This records the integer @var{int} as the type attribute of a symbol table
6395 @samp{.type} is associated only with COFF format output; when
6396 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
6397 directive but ignores it.
6403 @c only print the extra heading if both COFF and ELF are set
6404 @subheading ELF Version
6407 @cindex ELF symbol type
6408 @cindex symbol type, ELF
6409 @cindex @code{type} directive (ELF version)
6410 For ELF targets, the @code{.type} directive is used like this:
6413 .type @var{name} , @var{type description}
6416 This sets the type of symbol @var{name} to be either a
6417 function symbol or an object symbol. There are five different syntaxes
6418 supported for the @var{type description} field, in order to provide
6419 compatibility with various other assemblers.
6421 Because some of the characters used in these syntaxes (such as @samp{@@} and
6422 @samp{#}) are comment characters for some architectures, some of the syntaxes
6423 below do not work on all architectures. The first variant will be accepted by
6424 the GNU assembler on all architectures so that variant should be used for
6425 maximum portability, if you do not need to assemble your code with other
6428 The syntaxes supported are:
6431 .type <name> STT_<TYPE_IN_UPPER_CASE>
6432 .type <name>,#<type>
6433 .type <name>,@@<type>
6434 .type <name>,%<type>
6435 .type <name>,"<type>"
6438 The types supported are:
6443 Mark the symbol as being a function name.
6446 @itemx gnu_indirect_function
6447 Mark the symbol as an indirect function when evaluated during reloc
6448 processing. (This is only supported on Linux targeted assemblers).
6452 Mark the symbol as being a data object.
6456 Mark the symbol as being a thead-local data object.
6460 Mark the symbol as being a common data object.
6464 Does not mark the symbol in any way. It is supported just for completeness.
6466 @item gnu_unique_object
6467 Marks the symbol as being a globally unique data object. The dynamic linker
6468 will make sure that in the entire process there is just one symbol with this
6469 name and type in use. (This is only supported on Linux targeted assemblers).
6473 Note: Some targets support extra types in addition to those listed above.
6479 @section @code{.uleb128 @var{expressions}}
6481 @cindex @code{uleb128} directive
6482 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
6483 compact, variable length representation of numbers used by the DWARF
6484 symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}.
6488 @section @code{.val @var{addr}}
6490 @cindex @code{val} directive
6491 @cindex COFF value attribute
6492 @cindex value attribute, COFF
6493 This directive, permitted only within @code{.def}/@code{.endef} pairs,
6494 records the address @var{addr} as the value attribute of a symbol table
6498 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
6499 configured for @code{b.out}, it accepts this directive but ignores it.
6505 @section @code{.version "@var{string}"}
6507 @cindex @code{version} directive
6508 This directive creates a @code{.note} section and places into it an ELF
6509 formatted note of type NT_VERSION. The note's name is set to @code{string}.
6514 @section @code{.vtable_entry @var{table}, @var{offset}}
6516 @cindex @code{vtable_entry} directive
6517 This directive finds or creates a symbol @code{table} and creates a
6518 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
6521 @section @code{.vtable_inherit @var{child}, @var{parent}}
6523 @cindex @code{vtable_inherit} directive
6524 This directive finds the symbol @code{child} and finds or creates the symbol
6525 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
6526 parent whose addend is the value of the child symbol. As a special case the
6527 parent name of @code{0} is treated as referring to the @code{*ABS*} section.
6531 @section @code{.warning "@var{string}"}
6532 @cindex warning directive
6533 Similar to the directive @code{.error}
6534 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
6537 @section @code{.weak @var{names}}
6539 @cindex @code{weak} directive
6540 This directive sets the weak attribute on the comma separated list of symbol
6541 @code{names}. If the symbols do not already exist, they will be created.
6543 On COFF targets other than PE, weak symbols are a GNU extension. This
6544 directive sets the weak attribute on the comma separated list of symbol
6545 @code{names}. If the symbols do not already exist, they will be created.
6547 On the PE target, weak symbols are supported natively as weak aliases.
6548 When a weak symbol is created that is not an alias, GAS creates an
6549 alternate symbol to hold the default value.
6552 @section @code{.weakref @var{alias}, @var{target}}
6554 @cindex @code{weakref} directive
6555 This directive creates an alias to the target symbol that enables the symbol to
6556 be referenced with weak-symbol semantics, but without actually making it weak.
6557 If direct references or definitions of the symbol are present, then the symbol
6558 will not be weak, but if all references to it are through weak references, the
6559 symbol will be marked as weak in the symbol table.
6561 The effect is equivalent to moving all references to the alias to a separate
6562 assembly source file, renaming the alias to the symbol in it, declaring the
6563 symbol as weak there, and running a reloadable link to merge the object files
6564 resulting from the assembly of the new source file and the old source file that
6565 had the references to the alias removed.
6567 The alias itself never makes to the symbol table, and is entirely handled
6568 within the assembler.
6571 @section @code{.word @var{expressions}}
6573 @cindex @code{word} directive
6574 This directive expects zero or more @var{expressions}, of any section,
6575 separated by commas.
6578 For each expression, @command{@value{AS}} emits a 32-bit number.
6581 For each expression, @command{@value{AS}} emits a 16-bit number.
6586 The size of the number emitted, and its byte order,
6587 depend on what target computer the assembly is for.
6590 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
6591 @c happen---32-bit addressability, period; no long/short jumps.
6592 @ifset DIFF-TBL-KLUGE
6593 @cindex difference tables altered
6594 @cindex altered difference tables
6596 @emph{Warning: Special Treatment to support Compilers}
6600 Machines with a 32-bit address space, but that do less than 32-bit
6601 addressing, require the following special treatment. If the machine of
6602 interest to you does 32-bit addressing (or doesn't require it;
6603 @pxref{Machine Dependencies}), you can ignore this issue.
6606 In order to assemble compiler output into something that works,
6607 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
6608 Directives of the form @samp{.word sym1-sym2} are often emitted by
6609 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
6610 directive of the form @samp{.word sym1-sym2}, and the difference between
6611 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
6612 creates a @dfn{secondary jump table}, immediately before the next label.
6613 This secondary jump table is preceded by a short-jump to the
6614 first byte after the secondary table. This short-jump prevents the flow
6615 of control from accidentally falling into the new table. Inside the
6616 table is a long-jump to @code{sym2}. The original @samp{.word}
6617 contains @code{sym1} minus the address of the long-jump to
6620 If there were several occurrences of @samp{.word sym1-sym2} before the
6621 secondary jump table, all of them are adjusted. If there was a
6622 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
6623 long-jump to @code{sym4} is included in the secondary jump table,
6624 and the @code{.word} directives are adjusted to contain @code{sym3}
6625 minus the address of the long-jump to @code{sym4}; and so on, for as many
6626 entries in the original jump table as necessary.
6629 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
6630 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
6631 assembly language programmers.
6634 @c end DIFF-TBL-KLUGE
6637 @section Deprecated Directives
6639 @cindex deprecated directives
6640 @cindex obsolescent directives
6641 One day these directives won't work.
6642 They are included for compatibility with older assemblers.
6649 @node Object Attributes
6650 @chapter Object Attributes
6651 @cindex object attributes
6653 @command{@value{AS}} assembles source files written for a specific architecture
6654 into object files for that architecture. But not all object files are alike.
6655 Many architectures support incompatible variations. For instance, floating
6656 point arguments might be passed in floating point registers if the object file
6657 requires hardware floating point support---or floating point arguments might be
6658 passed in integer registers if the object file supports processors with no
6659 hardware floating point unit. Or, if two objects are built for different
6660 generations of the same architecture, the combination may require the
6661 newer generation at run-time.
6663 This information is useful during and after linking. At link time,
6664 @command{@value{LD}} can warn about incompatible object files. After link
6665 time, tools like @command{gdb} can use it to process the linked file
6668 Compatibility information is recorded as a series of object attributes. Each
6669 attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
6670 string, and indicates who sets the meaning of the tag. The tag is an integer,
6671 and indicates what property the attribute describes. The value may be a string
6672 or an integer, and indicates how the property affects this object. Missing
6673 attributes are the same as attributes with a zero value or empty string value.
6675 Object attributes were developed as part of the ABI for the ARM Architecture.
6676 The file format is documented in @cite{ELF for the ARM Architecture}.
6679 * GNU Object Attributes:: @sc{gnu} Object Attributes
6680 * Defining New Object Attributes:: Defining New Object Attributes
6683 @node GNU Object Attributes
6684 @section @sc{gnu} Object Attributes
6686 The @code{.gnu_attribute} directive records an object attribute
6687 with vendor @samp{gnu}.
6689 Except for @samp{Tag_compatibility}, which has both an integer and a string for
6690 its value, @sc{gnu} attributes have a string value if the tag number is odd and
6691 an integer value if the tag number is even. The second bit (@code{@var{tag} &
6692 2} is set for architecture-independent attributes and clear for
6693 architecture-dependent ones.
6695 @subsection Common @sc{gnu} attributes
6697 These attributes are valid on all architectures.
6700 @item Tag_compatibility (32)
6701 The compatibility attribute takes an integer flag value and a vendor name. If
6702 the flag value is 0, the file is compatible with other toolchains. If it is 1,
6703 then the file is only compatible with the named toolchain. If it is greater
6704 than 1, the file can only be processed by other toolchains under some private
6705 arrangement indicated by the flag value and the vendor name.
6708 @subsection MIPS Attributes
6711 @item Tag_GNU_MIPS_ABI_FP (4)
6712 The floating-point ABI used by this object file. The value will be:
6716 0 for files not affected by the floating-point ABI.
6718 1 for files using the hardware floating-point with a standard double-precision
6721 2 for files using the hardware floating-point ABI with a single-precision FPU.
6723 3 for files using the software floating-point ABI.
6725 4 for files using the hardware floating-point ABI with 64-bit wide
6726 double-precision floating-point registers and 32-bit wide general
6731 @subsection PowerPC Attributes
6734 @item Tag_GNU_Power_ABI_FP (4)
6735 The floating-point ABI used by this object file. The value will be:
6739 0 for files not affected by the floating-point ABI.
6741 1 for files using double-precision hardware floating-point ABI.
6743 2 for files using the software floating-point ABI.
6745 3 for files using single-precision hardware floating-point ABI.
6748 @item Tag_GNU_Power_ABI_Vector (8)
6749 The vector ABI used by this object file. The value will be:
6753 0 for files not affected by the vector ABI.
6755 1 for files using general purpose registers to pass vectors.
6757 2 for files using AltiVec registers to pass vectors.
6759 3 for files using SPE registers to pass vectors.
6763 @node Defining New Object Attributes
6764 @section Defining New Object Attributes
6766 If you want to define a new @sc{gnu} object attribute, here are the places you
6767 will need to modify. New attributes should be discussed on the @samp{binutils}
6772 This manual, which is the official register of attributes.
6774 The header for your architecture @file{include/elf}, to define the tag.
6776 The @file{bfd} support file for your architecture, to merge the attribute
6777 and issue any appropriate link warnings.
6779 Test cases in @file{ld/testsuite} for merging and link warnings.
6781 @file{binutils/readelf.c} to display your attribute.
6783 GCC, if you want the compiler to mark the attribute automatically.
6789 @node Machine Dependencies
6790 @chapter Machine Dependent Features
6792 @cindex machine dependencies
6793 The machine instruction sets are (almost by definition) different on
6794 each machine where @command{@value{AS}} runs. Floating point representations
6795 vary as well, and @command{@value{AS}} often supports a few additional
6796 directives or command-line options for compatibility with other
6797 assemblers on a particular platform. Finally, some versions of
6798 @command{@value{AS}} support special pseudo-instructions for branch
6801 This chapter discusses most of these differences, though it does not
6802 include details on any machine's instruction set. For details on that
6803 subject, see the hardware manufacturer's manual.
6807 * Alpha-Dependent:: Alpha Dependent Features
6810 * ARC-Dependent:: ARC Dependent Features
6813 * ARM-Dependent:: ARM Dependent Features
6816 * AVR-Dependent:: AVR Dependent Features
6819 * Blackfin-Dependent:: Blackfin Dependent Features
6822 * CR16-Dependent:: CR16 Dependent Features
6825 * CRIS-Dependent:: CRIS Dependent Features
6828 * D10V-Dependent:: D10V Dependent Features
6831 * D30V-Dependent:: D30V Dependent Features
6834 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6837 * HPPA-Dependent:: HPPA Dependent Features
6840 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
6843 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
6846 * i860-Dependent:: Intel 80860 Dependent Features
6849 * i960-Dependent:: Intel 80960 Dependent Features
6852 * IA-64-Dependent:: Intel IA-64 Dependent Features
6855 * IP2K-Dependent:: IP2K Dependent Features
6858 * LM32-Dependent:: LM32 Dependent Features
6861 * M32C-Dependent:: M32C Dependent Features
6864 * M32R-Dependent:: M32R Dependent Features
6867 * M68K-Dependent:: M680x0 Dependent Features
6870 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
6873 * MicroBlaze-Dependent:: MICROBLAZE Dependent Features
6876 * MIPS-Dependent:: MIPS Dependent Features
6879 * MMIX-Dependent:: MMIX Dependent Features
6882 * MSP430-Dependent:: MSP430 Dependent Features
6885 * SH-Dependent:: Renesas / SuperH SH Dependent Features
6886 * SH64-Dependent:: SuperH SH64 Dependent Features
6889 * PDP-11-Dependent:: PDP-11 Dependent Features
6892 * PJ-Dependent:: picoJava Dependent Features
6895 * PPC-Dependent:: PowerPC Dependent Features
6898 * RX-Dependent:: RX Dependent Features
6901 * S/390-Dependent:: IBM S/390 Dependent Features
6904 * SCORE-Dependent:: SCORE Dependent Features
6907 * Sparc-Dependent:: SPARC Dependent Features
6910 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
6913 * TIC6X-Dependent :: TI TMS320C6x Dependent Features
6916 * V850-Dependent:: V850 Dependent Features
6919 * Xtensa-Dependent:: Xtensa Dependent Features
6922 * Z80-Dependent:: Z80 Dependent Features
6925 * Z8000-Dependent:: Z8000 Dependent Features
6928 * Vax-Dependent:: VAX Dependent Features
6935 @c The following major nodes are *sections* in the GENERIC version, *chapters*
6936 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
6937 @c peculiarity: to preserve cross-references, there must be a node called
6938 @c "Machine Dependencies". Hence the conditional nodenames in each
6939 @c major node below. Node defaulting in makeinfo requires adjacency of
6940 @c node and sectioning commands; hence the repetition of @chapter BLAH
6941 @c in both conditional blocks.
6944 @include c-alpha.texi
6960 @include c-bfin.texi
6964 @include c-cr16.texi
6968 @include c-cris.texi
6973 @node Machine Dependencies
6974 @chapter Machine Dependent Features
6976 The machine instruction sets are different on each Renesas chip family,
6977 and there are also some syntax differences among the families. This
6978 chapter describes the specific @command{@value{AS}} features for each
6982 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6983 * SH-Dependent:: Renesas SH Dependent Features
6990 @include c-d10v.texi
6994 @include c-d30v.texi
6998 @include c-h8300.texi
7002 @include c-hppa.texi
7006 @include c-i370.texi
7010 @include c-i386.texi
7014 @include c-i860.texi
7018 @include c-i960.texi
7022 @include c-ia64.texi
7026 @include c-ip2k.texi
7030 @include c-lm32.texi
7034 @include c-m32c.texi
7038 @include c-m32r.texi
7042 @include c-m68k.texi
7046 @include c-m68hc11.texi
7050 @include c-microblaze.texi
7054 @include c-mips.texi
7058 @include c-mmix.texi
7062 @include c-msp430.texi
7066 @include c-ns32k.texi
7070 @include c-pdp11.texi
7086 @include c-s390.texi
7090 @include c-score.texi
7095 @include c-sh64.texi
7099 @include c-sparc.texi
7103 @include c-tic54x.texi
7107 @include c-tic6x.texi
7123 @include c-v850.texi
7127 @include c-xtensa.texi
7131 @c reverse effect of @down at top of generic Machine-Dep chapter
7135 @node Reporting Bugs
7136 @chapter Reporting Bugs
7137 @cindex bugs in assembler
7138 @cindex reporting bugs in assembler
7140 Your bug reports play an essential role in making @command{@value{AS}} reliable.
7142 Reporting a bug may help you by bringing a solution to your problem, or it may
7143 not. But in any case the principal function of a bug report is to help the
7144 entire community by making the next version of @command{@value{AS}} work better.
7145 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
7147 In order for a bug report to serve its purpose, you must include the
7148 information that enables us to fix the bug.
7151 * Bug Criteria:: Have you found a bug?
7152 * Bug Reporting:: How to report bugs
7156 @section Have You Found a Bug?
7157 @cindex bug criteria
7159 If you are not sure whether you have found a bug, here are some guidelines:
7162 @cindex fatal signal
7163 @cindex assembler crash
7164 @cindex crash of assembler
7166 If the assembler gets a fatal signal, for any input whatever, that is a
7167 @command{@value{AS}} bug. Reliable assemblers never crash.
7169 @cindex error on valid input
7171 If @command{@value{AS}} produces an error message for valid input, that is a bug.
7173 @cindex invalid input
7175 If @command{@value{AS}} does not produce an error message for invalid input, that
7176 is a bug. However, you should note that your idea of ``invalid input'' might
7177 be our idea of ``an extension'' or ``support for traditional practice''.
7180 If you are an experienced user of assemblers, your suggestions for improvement
7181 of @command{@value{AS}} are welcome in any case.
7185 @section How to Report Bugs
7187 @cindex assembler bugs, reporting
7189 A number of companies and individuals offer support for @sc{gnu} products. If
7190 you obtained @command{@value{AS}} from a support organization, we recommend you
7191 contact that organization first.
7193 You can find contact information for many support companies and
7194 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
7198 In any event, we also recommend that you send bug reports for @command{@value{AS}}
7202 The fundamental principle of reporting bugs usefully is this:
7203 @strong{report all the facts}. If you are not sure whether to state a
7204 fact or leave it out, state it!
7206 Often people omit facts because they think they know what causes the problem
7207 and assume that some details do not matter. Thus, you might assume that the
7208 name of a symbol you use in an example does not matter. Well, probably it does
7209 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
7210 happens to fetch from the location where that name is stored in memory;
7211 perhaps, if the name were different, the contents of that location would fool
7212 the assembler into doing the right thing despite the bug. Play it safe and
7213 give a specific, complete example. That is the easiest thing for you to do,
7214 and the most helpful.
7216 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
7217 it is new to us. Therefore, always write your bug reports on the assumption
7218 that the bug has not been reported previously.
7220 Sometimes people give a few sketchy facts and ask, ``Does this ring a
7221 bell?'' This cannot help us fix a bug, so it is basically useless. We
7222 respond by asking for enough details to enable us to investigate.
7223 You might as well expedite matters by sending them to begin with.
7225 To enable us to fix the bug, you should include all these things:
7229 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
7230 it with the @samp{--version} argument.
7232 Without this, we will not know whether there is any point in looking for
7233 the bug in the current version of @command{@value{AS}}.
7236 Any patches you may have applied to the @command{@value{AS}} source.
7239 The type of machine you are using, and the operating system name and
7243 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
7247 The command arguments you gave the assembler to assemble your example and
7248 observe the bug. To guarantee you will not omit something important, list them
7249 all. A copy of the Makefile (or the output from make) is sufficient.
7251 If we were to try to guess the arguments, we would probably guess wrong
7252 and then we might not encounter the bug.
7255 A complete input file that will reproduce the bug. If the bug is observed when
7256 the assembler is invoked via a compiler, send the assembler source, not the
7257 high level language source. Most compilers will produce the assembler source
7258 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
7259 the options @samp{-v --save-temps}; this will save the assembler source in a
7260 file with an extension of @file{.s}, and also show you exactly how
7261 @command{@value{AS}} is being run.
7264 A description of what behavior you observe that you believe is
7265 incorrect. For example, ``It gets a fatal signal.''
7267 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
7268 will certainly notice it. But if the bug is incorrect output, we might not
7269 notice unless it is glaringly wrong. You might as well not give us a chance to
7272 Even if the problem you experience is a fatal signal, you should still say so
7273 explicitly. Suppose something strange is going on, such as, your copy of
7274 @command{@value{AS}} is out of sync, or you have encountered a bug in the C
7275 library on your system. (This has happened!) Your copy might crash and ours
7276 would not. If you told us to expect a crash, then when ours fails to crash, we
7277 would know that the bug was not happening for us. If you had not told us to
7278 expect a crash, then we would not be able to draw any conclusion from our
7282 If you wish to suggest changes to the @command{@value{AS}} source, send us context
7283 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
7284 option. Always send diffs from the old file to the new file. If you even
7285 discuss something in the @command{@value{AS}} source, refer to it by context, not
7288 The line numbers in our development sources will not match those in your
7289 sources. Your line numbers would convey no useful information to us.
7292 Here are some things that are not necessary:
7296 A description of the envelope of the bug.
7298 Often people who encounter a bug spend a lot of time investigating
7299 which changes to the input file will make the bug go away and which
7300 changes will not affect it.
7302 This is often time consuming and not very useful, because the way we
7303 will find the bug is by running a single example under the debugger
7304 with breakpoints, not by pure deduction from a series of examples.
7305 We recommend that you save your time for something else.
7307 Of course, if you can find a simpler example to report @emph{instead}
7308 of the original one, that is a convenience for us. Errors in the
7309 output will be easier to spot, running under the debugger will take
7310 less time, and so on.
7312 However, simplification is not vital; if you do not want to do this,
7313 report the bug anyway and send us the entire test case you used.
7316 A patch for the bug.
7318 A patch for the bug does help us if it is a good one. But do not omit
7319 the necessary information, such as the test case, on the assumption that
7320 a patch is all we need. We might see problems with your patch and decide
7321 to fix the problem another way, or we might not understand it at all.
7323 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
7324 construct an example that will make the program follow a certain path through
7325 the code. If you do not send us the example, we will not be able to construct
7326 one, so we will not be able to verify that the bug is fixed.
7328 And if we cannot understand what bug you are trying to fix, or why your
7329 patch should be an improvement, we will not install it. A test case will
7330 help us to understand.
7333 A guess about what the bug is or what it depends on.
7335 Such guesses are usually wrong. Even we cannot guess right about such
7336 things without first using the debugger to find the facts.
7339 @node Acknowledgements
7340 @chapter Acknowledgements
7342 If you have contributed to GAS and your name isn't listed here,
7343 it is not meant as a slight. We just don't know about it. Send mail to the
7344 maintainer, and we'll correct the situation. Currently
7346 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
7348 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
7351 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
7352 information and the 68k series machines, most of the preprocessing pass, and
7353 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
7355 K. Richard Pixley maintained GAS for a while, adding various enhancements and
7356 many bug fixes, including merging support for several processors, breaking GAS
7357 up to handle multiple object file format back ends (including heavy rewrite,
7358 testing, an integration of the coff and b.out back ends), adding configuration
7359 including heavy testing and verification of cross assemblers and file splits
7360 and renaming, converted GAS to strictly ANSI C including full prototypes, added
7361 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
7362 port (including considerable amounts of reverse engineering), a SPARC opcode
7363 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
7364 assertions and made them work, much other reorganization, cleanup, and lint.
7366 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
7367 in format-specific I/O modules.
7369 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
7370 has done much work with it since.
7372 The Intel 80386 machine description was written by Eliot Dresselhaus.
7374 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
7376 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
7377 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
7379 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
7380 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
7381 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
7382 support a.out format.
7384 Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
7385 tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
7386 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
7387 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
7390 John Gilmore built the AMD 29000 support, added @code{.include} support, and
7391 simplified the configuration of which versions accept which directives. He
7392 updated the 68k machine description so that Motorola's opcodes always produced
7393 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
7394 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
7395 cross-compilation support, and one bug in relaxation that took a week and
7396 required the proverbial one-bit fix.
7398 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
7399 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
7400 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
7401 PowerPC assembler, and made a few other minor patches.
7403 Steve Chamberlain made GAS able to generate listings.
7405 Hewlett-Packard contributed support for the HP9000/300.
7407 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
7408 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
7409 formats). This work was supported by both the Center for Software Science at
7410 the University of Utah and Cygnus Support.
7412 Support for ELF format files has been worked on by Mark Eichin of Cygnus
7413 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
7414 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
7415 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
7416 and some initial 64-bit support).
7418 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
7420 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
7421 support for openVMS/Alpha.
7423 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
7426 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
7427 Inc.@: added support for Xtensa processors.
7429 Several engineers at Cygnus Support have also provided many small bug fixes and
7430 configuration enhancements.
7432 Jon Beniston added support for the Lattice Mico32 architecture.
7434 Many others have contributed large or small bugfixes and enhancements. If
7435 you have contributed significant work and are not mentioned on this list, and
7436 want to be, let us know. Some of the history has been lost; we are not
7437 intentionally leaving anyone out.
7439 @node GNU Free Documentation License
7440 @appendix GNU Free Documentation License
7444 @unnumbered AS Index
projects / deliverable / binutils-gdb.git / blob