1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
3 @c 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4 @c Free Software Foundation, Inc.
5 @c UPDATE!! On future updates--
6 @c (1) check for new machine-dep cmdline options in
7 @c md_parse_option definitions in config/tc-*.c
8 @c (2) for platform-specific directives, examine md_pseudo_op
10 @c (3) for object-format specific directives, examine obj_pseudo_op
12 @c (4) portable directives in potable[] in read.c
16 @macro gcctabopt{body}
19 @c defaults, config file may override:
24 @include asconfig.texi
29 @c common OR combinations of conditions
52 @set abnormal-separator
56 @settitle Using @value{AS}
59 @settitle Using @value{AS} (@value{TARGET})
61 @setchapternewpage odd
66 @c WARE! Some of the machine-dependent sections contain tables of machine
67 @c instructions. Except in multi-column format, these tables look silly.
68 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
69 @c the multi-col format is faked within @example sections.
71 @c Again unfortunately, the natural size that fits on a page, for these tables,
72 @c is different depending on whether or not smallbook is turned on.
73 @c This matters, because of order: text flow switches columns at each page
76 @c The format faked in this source works reasonably well for smallbook,
77 @c not well for the default large-page format. This manual expects that if you
78 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
79 @c tables in question. You can turn on one without the other at your
80 @c discretion, of course.
83 @c the insn tables look just as silly in info files regardless of smallbook,
84 @c might as well show 'em anyways.
90 * As: (as). The GNU assembler.
91 * Gas: (as). The GNU assembler.
100 This file documents the GNU Assembler "@value{AS}".
102 @c man begin COPYRIGHT
103 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
104 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
106 Permission is granted to copy, distribute and/or modify this document
107 under the terms of the GNU Free Documentation License, Version 1.3
108 or any later version published by the Free Software Foundation;
109 with no Invariant Sections, with no Front-Cover Texts, and with no
110 Back-Cover Texts. A copy of the license is included in the
111 section entitled ``GNU Free Documentation License''.
117 @title Using @value{AS}
118 @subtitle The @sc{gnu} Assembler
120 @subtitle for the @value{TARGET} family
122 @ifset VERSION_PACKAGE
124 @subtitle @value{VERSION_PACKAGE}
127 @subtitle Version @value{VERSION}
130 The Free Software Foundation Inc.@: thanks The Nice Computer
131 Company of Australia for loaning Dean Elsner to write the
132 first (Vax) version of @command{as} for Project @sc{gnu}.
133 The proprietors, management and staff of TNCCA thank FSF for
134 distracting the boss while they got some work
137 @author Dean Elsner, Jay Fenlason & friends
141 \hfill {\it Using {\tt @value{AS}}}\par
142 \hfill Edited by Cygnus Support\par
144 %"boxit" macro for figures:
145 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
146 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
147 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
148 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
149 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
152 @vskip 0pt plus 1filll
153 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
154 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
156 Permission is granted to copy, distribute and/or modify this document
157 under the terms of the GNU Free Documentation License, Version 1.3
158 or any later version published by the Free Software Foundation;
159 with no Invariant Sections, with no Front-Cover Texts, and with no
160 Back-Cover Texts. A copy of the license is included in the
161 section entitled ``GNU Free Documentation License''.
168 @top Using @value{AS}
170 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}}
171 @ifset VERSION_PACKAGE
172 @value{VERSION_PACKAGE}
174 version @value{VERSION}.
176 This version of the file describes @command{@value{AS}} configured to generate
177 code for @value{TARGET} architectures.
180 This document is distributed under the terms of the GNU Free
181 Documentation License. A copy of the license is included in the
182 section entitled ``GNU Free Documentation License''.
185 * Overview:: Overview
186 * Invoking:: Command-Line Options
188 * Sections:: Sections and Relocation
190 * Expressions:: Expressions
191 * Pseudo Ops:: Assembler Directives
193 * Object Attributes:: Object Attributes
195 * Machine Dependencies:: Machine Dependent Features
196 * Reporting Bugs:: Reporting Bugs
197 * Acknowledgements:: Who Did What
198 * GNU Free Documentation License:: GNU Free Documentation License
199 * AS Index:: AS Index
206 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
208 This version of the manual describes @command{@value{AS}} configured to generate
209 code for @value{TARGET} architectures.
213 @cindex invocation summary
214 @cindex option summary
215 @cindex summary of options
216 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
217 see @ref{Invoking,,Command-Line Options}.
219 @c man title AS the portable GNU assembler.
223 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
227 @c We don't use deffn and friends for the following because they seem
228 @c to be limited to one line for the header.
230 @c man begin SYNOPSIS
231 @value{AS} [@b{-a}[@b{cdghlns}][=@var{file}]] [@b{--alternate}] [@b{-D}]
232 [@b{--debug-prefix-map} @var{old}=@var{new}]
233 [@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}]
234 [@b{--gstabs+}] [@b{--gdwarf-2}] [@b{--help}] [@b{-I} @var{dir}] [@b{-J}]
235 [@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}]
236 [@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}]
237 [@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}] [@b{-o}
238 @var{objfile}] [@b{-R}] [@b{--reduce-memory-overheads}] [@b{--statistics}]
239 [@b{-v}] [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}]
240 [@b{--fatal-warnings}] [@b{-w}] [@b{-x}] [@b{-Z}] [@b{@@@var{FILE}}]
241 [@b{--target-help}] [@var{target-options}]
242 [@b{--}|@var{files} @dots{}]
244 @c Target dependent options are listed below. Keep the list sorted.
245 @c Add an empty line for separation.
248 @emph{Target Alpha options:}
250 [@b{-mdebug} | @b{-no-mdebug}]
251 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
252 [@b{-F}] [@b{-32addr}]
256 @emph{Target ARC options:}
262 @emph{Target ARM options:}
263 @c Don't document the deprecated options
264 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
265 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
266 [@b{-mfpu}=@var{floating-point-format}]
267 [@b{-mfloat-abi}=@var{abi}]
268 [@b{-meabi}=@var{ver}]
271 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
272 @b{-mapcs-reentrant}]
273 [@b{-mthumb-interwork}] [@b{-k}]
277 @emph{Target CRIS options:}
278 [@b{--underscore} | @b{--no-underscore}]
280 [@b{--emulation=criself} | @b{--emulation=crisaout}]
281 [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}]
282 @c Deprecated -- deliberately not documented.
287 @emph{Target D10V options:}
292 @emph{Target D30V options:}
293 [@b{-O}|@b{-n}|@b{-N}]
297 @emph{Target H8/300 options:}
301 @c HPPA has no machine-dependent assembler options (yet).
305 @emph{Target i386 options:}
306 [@b{--32}|@b{--64}] [@b{-n}]
307 [@b{-march}=@var{CPU}[+@var{EXTENSION}@dots{}]] [@b{-mtune}=@var{CPU}]
311 @emph{Target i960 options:}
312 @c see md_parse_option in tc-i960.c
313 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
315 [@b{-b}] [@b{-no-relax}]
319 @emph{Target IA-64 options:}
320 [@b{-mconstant-gp}|@b{-mauto-pic}]
321 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
323 [@b{-mtune=itanium1}|@b{-mtune=itanium2}]
324 [@b{-munwind-check=warning}|@b{-munwind-check=error}]
325 [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}]
326 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
330 @emph{Target IP2K options:}
331 [@b{-mip2022}|@b{-mip2022ext}]
335 @emph{Target M32C options:}
336 [@b{-m32c}|@b{-m16c}] [-relax] [-h-tick-hex]
340 @emph{Target M32R options:}
341 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
346 @emph{Target M680X0 options:}
347 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
351 @emph{Target M68HC11 options:}
352 [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}]
353 [@b{-mshort}|@b{-mlong}]
354 [@b{-mshort-double}|@b{-mlong-double}]
355 [@b{--force-long-branches}] [@b{--short-branches}]
356 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
357 [@b{--print-opcodes}] [@b{--generate-example}]
361 @emph{Target MCORE options:}
362 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
363 [@b{-mcpu=[210|340]}]
367 @emph{Target MIPS options:}
368 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]]
369 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
370 [@b{-non_shared}] [@b{-xgot} [@b{-mvxworks-pic}]
371 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
372 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
373 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}]
374 [@b{-mips64}] [@b{-mips64r2}]
375 [@b{-construct-floats}] [@b{-no-construct-floats}]
376 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
377 [@b{-mfix7000}] [@b{-mno-fix7000}]
378 [@b{-mips16}] [@b{-no-mips16}]
379 [@b{-msmartmips}] [@b{-mno-smartmips}]
380 [@b{-mips3d}] [@b{-no-mips3d}]
381 [@b{-mdmx}] [@b{-no-mdmx}]
382 [@b{-mdsp}] [@b{-mno-dsp}]
383 [@b{-mdspr2}] [@b{-mno-dspr2}]
384 [@b{-mmt}] [@b{-mno-mt}]
385 [@b{-mdebug}] [@b{-no-mdebug}]
386 [@b{-mpdr}] [@b{-mno-pdr}]
390 @emph{Target MMIX options:}
391 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
392 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
393 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
394 [@b{--linker-allocated-gregs}]
398 @emph{Target PDP11 options:}
399 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
400 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
401 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
405 @emph{Target picoJava options:}
410 @emph{Target PowerPC options:}
411 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
412 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}]
413 [@b{-mcom}|@b{-many}|@b{-maltivec}|@b{-mvsx}] [@b{-memb}]
414 [@b{-mregnames}|@b{-mno-regnames}]
415 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
416 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
417 [@b{-msolaris}|@b{-mno-solaris}]
421 @emph{Target s390 options:}
422 [@b{-m31}|@b{-m64}] [@b{-mesa}|@b{-mzarch}] [@b{-march}=@var{CPU}]
423 [@b{-mregnames}|@b{-mno-regnames}]
424 [@b{-mwarn-areg-zero}]
428 @emph{Target SCORE options:}
429 [@b{-EB}][@b{-EL}][@b{-FIXDD}][@b{-NWARN}]
430 [@b{-SCORE5}][@b{-SCORE5U}][@b{-SCORE7}][@b{-SCORE3}]
431 [@b{-march=score7}][@b{-march=score3}]
432 [@b{-USE_R1}][@b{-KPIC}][@b{-O0}][@b{-G} @var{num}][@b{-V}]
436 @emph{Target SPARC options:}
437 @c The order here is important. See c-sparc.texi.
438 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
439 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
440 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
445 @emph{Target TIC54X options:}
446 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
447 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
452 @emph{Target Z80 options:}
453 [@b{-z80}] [@b{-r800}]
454 [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}]
455 [@b{ -ignore-unportable-instructions}] [@b{-Wnup}]
456 [@b{ -warn-undocumented-instructions}] [@b{-Wud}]
457 [@b{ -warn-unportable-instructions}] [@b{-Wup}]
458 [@b{ -forbid-undocumented-instructions}] [@b{-Fud}]
459 [@b{ -forbid-unportable-instructions}] [@b{-Fup}]
463 @c Z8000 has no machine-dependent assembler options
467 @emph{Target Xtensa options:}
468 [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}]
469 [@b{--[no-]target-align}] [@b{--[no-]longcalls}]
470 [@b{--[no-]transform}]
471 [@b{--rename-section} @var{oldname}=@var{newname}]
479 @include at-file.texi
482 Turn on listings, in any of a variety of ways:
486 omit false conditionals
489 omit debugging directives
492 include general information, like @value{AS} version and options passed
495 include high-level source
501 include macro expansions
504 omit forms processing
510 set the name of the listing file
513 You may combine these options; for example, use @samp{-aln} for assembly
514 listing without forms processing. The @samp{=file} option, if used, must be
515 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
518 Begin in alternate macro mode.
520 @xref{Altmacro,,@code{.altmacro}}.
524 Ignored. This option is accepted for script compatibility with calls to
527 @item --debug-prefix-map @var{old}=@var{new}
528 When assembling files in directory @file{@var{old}}, record debugging
529 information describing them as in @file{@var{new}} instead.
531 @item --defsym @var{sym}=@var{value}
532 Define the symbol @var{sym} to be @var{value} before assembling the input file.
533 @var{value} must be an integer constant. As in C, a leading @samp{0x}
534 indicates a hexadecimal value, and a leading @samp{0} indicates an octal
535 value. The value of the symbol can be overridden inside a source file via the
536 use of a @code{.set} pseudo-op.
539 ``fast''---skip whitespace and comment preprocessing (assume source is
544 Generate debugging information for each assembler source line using whichever
545 debug format is preferred by the target. This currently means either STABS,
549 Generate stabs debugging information for each assembler line. This
550 may help debugging assembler code, if the debugger can handle it.
553 Generate stabs debugging information for each assembler line, with GNU
554 extensions that probably only gdb can handle, and that could make other
555 debuggers crash or refuse to read your program. This
556 may help debugging assembler code. Currently the only GNU extension is
557 the location of the current working directory at assembling time.
560 Generate DWARF2 debugging information for each assembler line. This
561 may help debugging assembler code, if the debugger can handle it. Note---this
562 option is only supported by some targets, not all of them.
565 Print a summary of the command line options and exit.
568 Print a summary of all target specific options and exit.
571 Add directory @var{dir} to the search list for @code{.include} directives.
574 Don't warn about signed overflow.
577 @ifclear DIFF-TBL-KLUGE
578 This option is accepted but has no effect on the @value{TARGET} family.
580 @ifset DIFF-TBL-KLUGE
581 Issue warnings when difference tables altered for long displacements.
586 Keep (in the symbol table) local symbols. These symbols start with
587 system-specific local label prefixes, typically @samp{.L} for ELF systems
588 or @samp{L} for traditional a.out systems.
593 @item --listing-lhs-width=@var{number}
594 Set the maximum width, in words, of the output data column for an assembler
595 listing to @var{number}.
597 @item --listing-lhs-width2=@var{number}
598 Set the maximum width, in words, of the output data column for continuation
599 lines in an assembler listing to @var{number}.
601 @item --listing-rhs-width=@var{number}
602 Set the maximum width of an input source line, as displayed in a listing, to
605 @item --listing-cont-lines=@var{number}
606 Set the maximum number of lines printed in a listing for a single line of input
609 @item -o @var{objfile}
610 Name the object-file output from @command{@value{AS}} @var{objfile}.
613 Fold the data section into the text section.
615 @kindex --hash-size=@var{number}
616 Set the default size of GAS's hash tables to a prime number close to
617 @var{number}. Increasing this value can reduce the length of time it takes the
618 assembler to perform its tasks, at the expense of increasing the assembler's
619 memory requirements. Similarly reducing this value can reduce the memory
620 requirements at the expense of speed.
622 @item --reduce-memory-overheads
623 This option reduces GAS's memory requirements, at the expense of making the
624 assembly processes slower. Currently this switch is a synonym for
625 @samp{--hash-size=4051}, but in the future it may have other effects as well.
628 Print the maximum space (in bytes) and total time (in seconds) used by
631 @item --strip-local-absolute
632 Remove local absolute symbols from the outgoing symbol table.
636 Print the @command{as} version.
639 Print the @command{as} version and exit.
643 Suppress warning messages.
645 @item --fatal-warnings
646 Treat warnings as errors.
649 Don't suppress warning messages or treat them as errors.
658 Generate an object file even after errors.
660 @item -- | @var{files} @dots{}
661 Standard input, or source files to assemble.
666 The following options are available when @value{AS} is configured for
671 This option selects the core processor variant.
673 Select either big-endian (-EB) or little-endian (-EL) output.
678 The following options are available when @value{AS} is configured for the ARM
682 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
683 Specify which ARM processor variant is the target.
684 @item -march=@var{architecture}[+@var{extension}@dots{}]
685 Specify which ARM architecture variant is used by the target.
686 @item -mfpu=@var{floating-point-format}
687 Select which Floating Point architecture is the target.
688 @item -mfloat-abi=@var{abi}
689 Select which floating point ABI is in use.
691 Enable Thumb only instruction decoding.
692 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
693 Select which procedure calling convention is in use.
695 Select either big-endian (-EB) or little-endian (-EL) output.
696 @item -mthumb-interwork
697 Specify that the code has been generated with interworking between Thumb and
700 Specify that PIC code has been generated.
705 See the info pages for documentation of the CRIS-specific options.
709 The following options are available when @value{AS} is configured for
712 @cindex D10V optimization
713 @cindex optimization, D10V
715 Optimize output by parallelizing instructions.
720 The following options are available when @value{AS} is configured for a D30V
723 @cindex D30V optimization
724 @cindex optimization, D30V
726 Optimize output by parallelizing instructions.
730 Warn when nops are generated.
732 @cindex D30V nops after 32-bit multiply
734 Warn when a nop after a 32-bit multiply instruction is generated.
739 The following options are available when @value{AS} is configured for the
740 Intel 80960 processor.
743 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
744 Specify which variant of the 960 architecture is the target.
747 Add code to collect statistics about branches taken.
750 Do not alter compare-and-branch instructions for long displacements;
757 The following options are available when @value{AS} is configured for the
763 Specifies that the extended IP2022 instructions are allowed.
766 Restores the default behaviour, which restricts the permitted instructions to
767 just the basic IP2022 ones.
773 The following options are available when @value{AS} is configured for the
774 Renesas M32C and M16C processors.
779 Assemble M32C instructions.
782 Assemble M16C instructions (the default).
785 Enable support for link-time relaxations.
788 Support H'00 style hex constants in addition to 0x00 style.
794 The following options are available when @value{AS} is configured for the
795 Renesas M32R (formerly Mitsubishi M32R) series.
800 Specify which processor in the M32R family is the target. The default
801 is normally the M32R, but this option changes it to the M32RX.
803 @item --warn-explicit-parallel-conflicts or --Wp
804 Produce warning messages when questionable parallel constructs are
807 @item --no-warn-explicit-parallel-conflicts or --Wnp
808 Do not produce warning messages when questionable parallel constructs are
815 The following options are available when @value{AS} is configured for the
816 Motorola 68000 series.
821 Shorten references to undefined symbols, to one word instead of two.
823 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
824 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
825 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
826 Specify what processor in the 68000 family is the target. The default
827 is normally the 68020, but this can be changed at configuration time.
829 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
830 The target machine does (or does not) have a floating-point coprocessor.
831 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
832 the basic 68000 is not compatible with the 68881, a combination of the
833 two can be specified, since it's possible to do emulation of the
834 coprocessor instructions with the main processor.
836 @item -m68851 | -mno-68851
837 The target machine does (or does not) have a memory-management
838 unit coprocessor. The default is to assume an MMU for 68020 and up.
845 For details about the PDP-11 machine dependent features options,
846 see @ref{PDP-11-Options}.
849 @item -mpic | -mno-pic
850 Generate position-independent (or position-dependent) code. The
851 default is @option{-mpic}.
854 @itemx -mall-extensions
855 Enable all instruction set extensions. This is the default.
857 @item -mno-extensions
858 Disable all instruction set extensions.
860 @item -m@var{extension} | -mno-@var{extension}
861 Enable (or disable) a particular instruction set extension.
864 Enable the instruction set extensions supported by a particular CPU, and
865 disable all other extensions.
867 @item -m@var{machine}
868 Enable the instruction set extensions supported by a particular machine
869 model, and disable all other extensions.
875 The following options are available when @value{AS} is configured for
876 a picoJava processor.
880 @cindex PJ endianness
881 @cindex endianness, PJ
882 @cindex big endian output, PJ
884 Generate ``big endian'' format output.
886 @cindex little endian output, PJ
888 Generate ``little endian'' format output.
894 The following options are available when @value{AS} is configured for the
895 Motorola 68HC11 or 68HC12 series.
899 @item -m68hc11 | -m68hc12 | -m68hcs12
900 Specify what processor is the target. The default is
901 defined by the configuration option when building the assembler.
904 Specify to use the 16-bit integer ABI.
907 Specify to use the 32-bit integer ABI.
910 Specify to use the 32-bit double ABI.
913 Specify to use the 64-bit double ABI.
915 @item --force-long-branches
916 Relative branches are turned into absolute ones. This concerns
917 conditional branches, unconditional branches and branches to a
920 @item -S | --short-branches
921 Do not turn relative branches into absolute ones
922 when the offset is out of range.
924 @item --strict-direct-mode
925 Do not turn the direct addressing mode into extended addressing mode
926 when the instruction does not support direct addressing mode.
928 @item --print-insn-syntax
929 Print the syntax of instruction in case of error.
931 @item --print-opcodes
932 print the list of instructions with syntax and then exit.
934 @item --generate-example
935 print an example of instruction for each possible instruction and then exit.
936 This option is only useful for testing @command{@value{AS}}.
942 The following options are available when @command{@value{AS}} is configured
943 for the SPARC architecture:
946 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
947 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
948 Explicitly select a variant of the SPARC architecture.
950 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
951 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
953 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
954 UltraSPARC extensions.
956 @item -xarch=v8plus | -xarch=v8plusa
957 For compatibility with the Solaris v9 assembler. These options are
958 equivalent to -Av8plus and -Av8plusa, respectively.
961 Warn when the assembler switches to another architecture.
966 The following options are available when @value{AS} is configured for the 'c54x
971 Enable extended addressing mode. All addresses and relocations will assume
972 extended addressing (usually 23 bits).
973 @item -mcpu=@var{CPU_VERSION}
974 Sets the CPU version being compiled for.
975 @item -merrors-to-file @var{FILENAME}
976 Redirect error output to a file, for broken systems which don't support such
977 behaviour in the shell.
982 The following options are available when @value{AS} is configured for
983 a @sc{mips} processor.
987 This option sets the largest size of an object that can be referenced
988 implicitly with the @code{gp} register. It is only accepted for targets that
989 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
991 @cindex MIPS endianness
992 @cindex endianness, MIPS
993 @cindex big endian output, MIPS
995 Generate ``big endian'' format output.
997 @cindex little endian output, MIPS
999 Generate ``little endian'' format output.
1011 Generate code for a particular @sc{mips} Instruction Set Architecture level.
1012 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
1013 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
1014 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
1015 @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and
1017 correspond to generic
1018 @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64},
1019 and @samp{MIPS64 Release 2}
1020 ISA processors, respectively.
1022 @item -march=@var{CPU}
1023 Generate code for a particular @sc{mips} cpu.
1025 @item -mtune=@var{cpu}
1026 Schedule and tune for a particular @sc{mips} cpu.
1030 Cause nops to be inserted if the read of the destination register
1031 of an mfhi or mflo instruction occurs in the following two instructions.
1035 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
1036 section instead of the standard ELF .stabs sections.
1040 Control generation of @code{.pdr} sections.
1044 The register sizes are normally inferred from the ISA and ABI, but these
1045 flags force a certain group of registers to be treated as 32 bits wide at
1046 all times. @samp{-mgp32} controls the size of general-purpose registers
1047 and @samp{-mfp32} controls the size of floating-point registers.
1051 Generate code for the MIPS 16 processor. This is equivalent to putting
1052 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
1053 turns off this option.
1056 @itemx -mno-smartmips
1057 Enables the SmartMIPS extension to the MIPS32 instruction set. This is
1058 equivalent to putting @code{.set smartmips} at the start of the assembly file.
1059 @samp{-mno-smartmips} turns off this option.
1063 Generate code for the MIPS-3D Application Specific Extension.
1064 This tells the assembler to accept MIPS-3D instructions.
1065 @samp{-no-mips3d} turns off this option.
1069 Generate code for the MDMX Application Specific Extension.
1070 This tells the assembler to accept MDMX instructions.
1071 @samp{-no-mdmx} turns off this option.
1075 Generate code for the DSP Release 1 Application Specific Extension.
1076 This tells the assembler to accept DSP Release 1 instructions.
1077 @samp{-mno-dsp} turns off this option.
1081 Generate code for the DSP Release 2 Application Specific Extension.
1082 This option implies -mdsp.
1083 This tells the assembler to accept DSP Release 2 instructions.
1084 @samp{-mno-dspr2} turns off this option.
1088 Generate code for the MT Application Specific Extension.
1089 This tells the assembler to accept MT instructions.
1090 @samp{-mno-mt} turns off this option.
1092 @item --construct-floats
1093 @itemx --no-construct-floats
1094 The @samp{--no-construct-floats} option disables the construction of
1095 double width floating point constants by loading the two halves of the
1096 value into the two single width floating point registers that make up
1097 the double width register. By default @samp{--construct-floats} is
1098 selected, allowing construction of these floating point constants.
1101 @item --emulation=@var{name}
1102 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
1103 for some other target, in all respects, including output format (choosing
1104 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
1105 debugging information or store symbol table information, and default
1106 endianness. The available configuration names are: @samp{mipsecoff},
1107 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
1108 @samp{mipsbelf}. The first two do not alter the default endianness from that
1109 of the primary target for which the assembler was configured; the others change
1110 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
1111 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
1112 selection in any case.
1114 This option is currently supported only when the primary target
1115 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
1116 Furthermore, the primary target or others specified with
1117 @samp{--enable-targets=@dots{}} at configuration time must include support for
1118 the other format, if both are to be available. For example, the Irix 5
1119 configuration includes support for both.
1121 Eventually, this option will support more configurations, with more
1122 fine-grained control over the assembler's behavior, and will be supported for
1126 @command{@value{AS}} ignores this option. It is accepted for compatibility with
1133 Control how to deal with multiplication overflow and division by zero.
1134 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
1135 (and only work for Instruction Set Architecture level 2 and higher);
1136 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
1140 When this option is used, @command{@value{AS}} will issue a warning every
1141 time it generates a nop instruction from a macro.
1146 The following options are available when @value{AS} is configured for
1152 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1153 The command line option @samp{-nojsri2bsr} can be used to disable it.
1157 Enable or disable the silicon filter behaviour. By default this is disabled.
1158 The default can be overridden by the @samp{-sifilter} command line option.
1161 Alter jump instructions for long displacements.
1163 @item -mcpu=[210|340]
1164 Select the cpu type on the target hardware. This controls which instructions
1168 Assemble for a big endian target.
1171 Assemble for a little endian target.
1177 See the info pages for documentation of the MMIX-specific options.
1181 The following options are available when @value{AS} is configured for the s390
1187 Select the word size, either 31/32 bits or 64 bits.
1190 Select the architecture mode, either the Enterprise System
1191 Architecture (esa) or the z/Architecture mode (zarch).
1192 @item -march=@var{processor}
1193 Specify which s390 processor variant is the target, @samp{g6}, @samp{g6},
1194 @samp{z900}, @samp{z990}, @samp{z9-109}, @samp{z9-ec}, or @samp{z10}.
1196 @itemx -mno-regnames
1197 Allow or disallow symbolic names for registers.
1198 @item -mwarn-areg-zero
1199 Warn whenever the operand for a base or index register has been specified
1200 but evaluates to zero.
1205 The following options are available when @value{AS} is configured for
1206 an Xtensa processor.
1209 @item --text-section-literals | --no-text-section-literals
1210 With @option{--text-@-section-@-literals}, literal pools are interspersed
1211 in the text section. The default is
1212 @option{--no-@-text-@-section-@-literals}, which places literals in a
1213 separate section in the output file. These options only affect literals
1214 referenced via PC-relative @code{L32R} instructions; literals for
1215 absolute mode @code{L32R} instructions are handled separately.
1217 @item --absolute-literals | --no-absolute-literals
1218 Indicate to the assembler whether @code{L32R} instructions use absolute
1219 or PC-relative addressing. The default is to assume absolute addressing
1220 if the Xtensa processor includes the absolute @code{L32R} addressing
1221 option. Otherwise, only the PC-relative @code{L32R} mode can be used.
1223 @item --target-align | --no-target-align
1224 Enable or disable automatic alignment to reduce branch penalties at the
1225 expense of some code density. The default is @option{--target-@-align}.
1227 @item --longcalls | --no-longcalls
1228 Enable or disable transformation of call instructions to allow calls
1229 across a greater range of addresses. The default is
1230 @option{--no-@-longcalls}.
1232 @item --transform | --no-transform
1233 Enable or disable all assembler transformations of Xtensa instructions.
1234 The default is @option{--transform};
1235 @option{--no-transform} should be used only in the rare cases when the
1236 instructions must be exactly as specified in the assembly source.
1238 @item --rename-section @var{oldname}=@var{newname}
1239 When generating output sections, rename the @var{oldname} section to
1245 The following options are available when @value{AS} is configured for
1246 a Z80 family processor.
1249 Assemble for Z80 processor.
1251 Assemble for R800 processor.
1252 @item -ignore-undocumented-instructions
1254 Assemble undocumented Z80 instructions that also work on R800 without warning.
1255 @item -ignore-unportable-instructions
1257 Assemble all undocumented Z80 instructions without warning.
1258 @item -warn-undocumented-instructions
1260 Issue a warning for undocumented Z80 instructions that also work on R800.
1261 @item -warn-unportable-instructions
1263 Issue a warning for undocumented Z80 instructions that do not work on R800.
1264 @item -forbid-undocumented-instructions
1266 Treat all undocumented instructions as errors.
1267 @item -forbid-unportable-instructions
1269 Treat undocumented Z80 instructions that do not work on R800 as errors.
1276 * Manual:: Structure of this Manual
1277 * GNU Assembler:: The GNU Assembler
1278 * Object Formats:: Object File Formats
1279 * Command Line:: Command Line
1280 * Input Files:: Input Files
1281 * Object:: Output (Object) File
1282 * Errors:: Error and Warning Messages
1286 @section Structure of this Manual
1288 @cindex manual, structure and purpose
1289 This manual is intended to describe what you need to know to use
1290 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1291 notation for symbols, constants, and expressions; the directives that
1292 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1295 We also cover special features in the @value{TARGET}
1296 configuration of @command{@value{AS}}, including assembler directives.
1299 This manual also describes some of the machine-dependent features of
1300 various flavors of the assembler.
1303 @cindex machine instructions (not covered)
1304 On the other hand, this manual is @emph{not} intended as an introduction
1305 to programming in assembly language---let alone programming in general!
1306 In a similar vein, we make no attempt to introduce the machine
1307 architecture; we do @emph{not} describe the instruction set, standard
1308 mnemonics, registers or addressing modes that are standard to a
1309 particular architecture.
1311 You may want to consult the manufacturer's
1312 machine architecture manual for this information.
1316 For information on the H8/300 machine instruction set, see @cite{H8/300
1317 Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series
1318 Programming Manual} (Renesas).
1321 For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set,
1322 see @cite{SH-Microcomputer User's Manual} (Renesas) or
1323 @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and
1324 @cite{SuperH (SH) 64-Bit RISC Series} (SuperH).
1327 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1331 @c I think this is premature---doc@cygnus.com, 17jan1991
1333 Throughout this manual, we assume that you are running @dfn{GNU},
1334 the portable operating system from the @dfn{Free Software
1335 Foundation, Inc.}. This restricts our attention to certain kinds of
1336 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1337 once this assumption is granted examples and definitions need less
1340 @command{@value{AS}} is part of a team of programs that turn a high-level
1341 human-readable series of instructions into a low-level
1342 computer-readable series of instructions. Different versions of
1343 @command{@value{AS}} are used for different kinds of computer.
1346 @c There used to be a section "Terminology" here, which defined
1347 @c "contents", "byte", "word", and "long". Defining "word" to any
1348 @c particular size is confusing when the .word directive may generate 16
1349 @c bits on one machine and 32 bits on another; in general, for the user
1350 @c version of this manual, none of these terms seem essential to define.
1351 @c They were used very little even in the former draft of the manual;
1352 @c this draft makes an effort to avoid them (except in names of
1356 @section The GNU Assembler
1358 @c man begin DESCRIPTION
1360 @sc{gnu} @command{as} is really a family of assemblers.
1362 This manual describes @command{@value{AS}}, a member of that family which is
1363 configured for the @value{TARGET} architectures.
1365 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1366 should find a fairly similar environment when you use it on another
1367 architecture. Each version has much in common with the others,
1368 including object file formats, most assembler directives (often called
1369 @dfn{pseudo-ops}) and assembler syntax.@refill
1371 @cindex purpose of @sc{gnu} assembler
1372 @command{@value{AS}} is primarily intended to assemble the output of the
1373 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1374 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1375 assemble correctly everything that other assemblers for the same
1376 machine would assemble.
1378 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1381 @c This remark should appear in generic version of manual; assumption
1382 @c here is that generic version sets M680x0.
1383 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1384 assembler for the same architecture; for example, we know of several
1385 incompatible versions of 680x0 assembly language syntax.
1390 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1391 program in one pass of the source file. This has a subtle impact on the
1392 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1394 @node Object Formats
1395 @section Object File Formats
1397 @cindex object file format
1398 The @sc{gnu} assembler can be configured to produce several alternative
1399 object file formats. For the most part, this does not affect how you
1400 write assembly language programs; but directives for debugging symbols
1401 are typically different in different file formats. @xref{Symbol
1402 Attributes,,Symbol Attributes}.
1405 For the @value{TARGET} target, @command{@value{AS}} is configured to produce
1406 @value{OBJ-NAME} format object files.
1408 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1410 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1411 @code{b.out} or COFF format object files.
1414 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1415 SOM or ELF format object files.
1420 @section Command Line
1422 @cindex command line conventions
1424 After the program name @command{@value{AS}}, the command line may contain
1425 options and file names. Options may appear in any order, and may be
1426 before, after, or between file names. The order of file names is
1429 @cindex standard input, as input file
1431 @file{--} (two hyphens) by itself names the standard input file
1432 explicitly, as one of the files for @command{@value{AS}} to assemble.
1434 @cindex options, command line
1435 Except for @samp{--} any command line argument that begins with a
1436 hyphen (@samp{-}) is an option. Each option changes the behavior of
1437 @command{@value{AS}}. No option changes the way another option works. An
1438 option is a @samp{-} followed by one or more letters; the case of
1439 the letter is important. All options are optional.
1441 Some options expect exactly one file name to follow them. The file
1442 name may either immediately follow the option's letter (compatible
1443 with older assemblers) or it may be the next command argument (@sc{gnu}
1444 standard). These two command lines are equivalent:
1447 @value{AS} -o my-object-file.o mumble.s
1448 @value{AS} -omy-object-file.o mumble.s
1452 @section Input Files
1455 @cindex source program
1456 @cindex files, input
1457 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1458 describe the program input to one run of @command{@value{AS}}. The program may
1459 be in one or more files; how the source is partitioned into files
1460 doesn't change the meaning of the source.
1462 @c I added "con" prefix to "catenation" just to prove I can overcome my
1463 @c APL training... doc@cygnus.com
1464 The source program is a concatenation of the text in all the files, in the
1467 @c man begin DESCRIPTION
1468 Each time you run @command{@value{AS}} it assembles exactly one source
1469 program. The source program is made up of one or more files.
1470 (The standard input is also a file.)
1472 You give @command{@value{AS}} a command line that has zero or more input file
1473 names. The input files are read (from left file name to right). A
1474 command line argument (in any position) that has no special meaning
1475 is taken to be an input file name.
1477 If you give @command{@value{AS}} no file names it attempts to read one input file
1478 from the @command{@value{AS}} standard input, which is normally your terminal. You
1479 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1482 Use @samp{--} if you need to explicitly name the standard input file
1483 in your command line.
1485 If the source is empty, @command{@value{AS}} produces a small, empty object
1490 @subheading Filenames and Line-numbers
1492 @cindex input file linenumbers
1493 @cindex line numbers, in input files
1494 There are two ways of locating a line in the input file (or files) and
1495 either may be used in reporting error messages. One way refers to a line
1496 number in a physical file; the other refers to a line number in a
1497 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1499 @dfn{Physical files} are those files named in the command line given
1500 to @command{@value{AS}}.
1502 @dfn{Logical files} are simply names declared explicitly by assembler
1503 directives; they bear no relation to physical files. Logical file names help
1504 error messages reflect the original source file, when @command{@value{AS}} source
1505 is itself synthesized from other files. @command{@value{AS}} understands the
1506 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1507 @ref{File,,@code{.file}}.
1510 @section Output (Object) File
1516 Every time you run @command{@value{AS}} it produces an output file, which is
1517 your assembly language program translated into numbers. This file
1518 is the object file. Its default name is
1526 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1528 You can give it another name by using the @option{-o} option. Conventionally,
1529 object file names end with @file{.o}. The default name is used for historical
1530 reasons: older assemblers were capable of assembling self-contained programs
1531 directly into a runnable program. (For some formats, this isn't currently
1532 possible, but it can be done for the @code{a.out} format.)
1536 The object file is meant for input to the linker @code{@value{LD}}. It contains
1537 assembled program code, information to help @code{@value{LD}} integrate
1538 the assembled program into a runnable file, and (optionally) symbolic
1539 information for the debugger.
1541 @c link above to some info file(s) like the description of a.out.
1542 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1545 @section Error and Warning Messages
1547 @c man begin DESCRIPTION
1549 @cindex error messages
1550 @cindex warning messages
1551 @cindex messages from assembler
1552 @command{@value{AS}} may write warnings and error messages to the standard error
1553 file (usually your terminal). This should not happen when a compiler
1554 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1555 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1556 grave problem that stops the assembly.
1560 @cindex format of warning messages
1561 Warning messages have the format
1564 file_name:@b{NNN}:Warning Message Text
1568 @cindex line numbers, in warnings/errors
1569 (where @b{NNN} is a line number). If a logical file name has been given
1570 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1571 the current input file is used. If a logical line number was given
1573 (@pxref{Line,,@code{.line}})
1575 then it is used to calculate the number printed,
1576 otherwise the actual line in the current source file is printed. The
1577 message text is intended to be self explanatory (in the grand Unix
1580 @cindex format of error messages
1581 Error messages have the format
1583 file_name:@b{NNN}:FATAL:Error Message Text
1585 The file name and line number are derived as for warning
1586 messages. The actual message text may be rather less explanatory
1587 because many of them aren't supposed to happen.
1590 @chapter Command-Line Options
1592 @cindex options, all versions of assembler
1593 This chapter describes command-line options available in @emph{all}
1594 versions of the @sc{gnu} assembler; see @ref{Machine Dependencies},
1595 for options specific
1597 to the @value{TARGET} target.
1600 to particular machine architectures.
1603 @c man begin DESCRIPTION
1605 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler,
1606 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1607 The assembler arguments must be separated from each other (and the @samp{-Wa})
1608 by commas. For example:
1611 gcc -c -g -O -Wa,-alh,-L file.c
1615 This passes two options to the assembler: @samp{-alh} (emit a listing to
1616 standard output with high-level and assembly source) and @samp{-L} (retain
1617 local symbols in the symbol table).
1619 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1620 command-line options are automatically passed to the assembler by the compiler.
1621 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1622 precisely what options it passes to each compilation pass, including the
1628 * a:: -a[cdghlns] enable listings
1629 * alternate:: --alternate enable alternate macro syntax
1630 * D:: -D for compatibility
1631 * f:: -f to work faster
1632 * I:: -I for .include search path
1633 @ifclear DIFF-TBL-KLUGE
1634 * K:: -K for compatibility
1636 @ifset DIFF-TBL-KLUGE
1637 * K:: -K for difference tables
1640 * L:: -L to retain local symbols
1641 * listing:: --listing-XXX to configure listing output
1642 * M:: -M or --mri to assemble in MRI compatibility mode
1643 * MD:: --MD for dependency tracking
1644 * o:: -o to name the object file
1645 * R:: -R to join data and text sections
1646 * statistics:: --statistics to see statistics about assembly
1647 * traditional-format:: --traditional-format for compatible output
1648 * v:: -v to announce version
1649 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1650 * Z:: -Z to make object file even after errors
1654 @section Enable Listings: @option{-a[cdghlns]}
1664 @cindex listings, enabling
1665 @cindex assembly listings, enabling
1667 These options enable listing output from the assembler. By itself,
1668 @samp{-a} requests high-level, assembly, and symbols listing.
1669 You can use other letters to select specific options for the list:
1670 @samp{-ah} requests a high-level language listing,
1671 @samp{-al} requests an output-program assembly listing, and
1672 @samp{-as} requests a symbol table listing.
1673 High-level listings require that a compiler debugging option like
1674 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1677 Use the @samp{-ag} option to print a first section with general assembly
1678 information, like @value{AS} version, switches passed, or time stamp.
1680 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1681 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1682 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1683 omitted from the listing.
1685 Use the @samp{-ad} option to omit debugging directives from the
1688 Once you have specified one of these options, you can further control
1689 listing output and its appearance using the directives @code{.list},
1690 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1692 The @samp{-an} option turns off all forms processing.
1693 If you do not request listing output with one of the @samp{-a} options, the
1694 listing-control directives have no effect.
1696 The letters after @samp{-a} may be combined into one option,
1697 @emph{e.g.}, @samp{-aln}.
1699 Note if the assembler source is coming from the standard input (e.g.,
1701 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1702 is being used) then the listing will not contain any comments or preprocessor
1703 directives. This is because the listing code buffers input source lines from
1704 stdin only after they have been preprocessed by the assembler. This reduces
1705 memory usage and makes the code more efficient.
1708 @section @option{--alternate}
1711 Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}.
1714 @section @option{-D}
1717 This option has no effect whatsoever, but it is accepted to make it more
1718 likely that scripts written for other assemblers also work with
1719 @command{@value{AS}}.
1722 @section Work Faster: @option{-f}
1725 @cindex trusted compiler
1726 @cindex faster processing (@option{-f})
1727 @samp{-f} should only be used when assembling programs written by a
1728 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1729 and comment preprocessing on
1730 the input file(s) before assembling them. @xref{Preprocessing,
1734 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1735 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1740 @section @code{.include} Search Path: @option{-I} @var{path}
1742 @kindex -I @var{path}
1743 @cindex paths for @code{.include}
1744 @cindex search path for @code{.include}
1745 @cindex @code{include} directive search path
1746 Use this option to add a @var{path} to the list of directories
1747 @command{@value{AS}} searches for files specified in @code{.include}
1748 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1749 many times as necessary to include a variety of paths. The current
1750 working directory is always searched first; after that, @command{@value{AS}}
1751 searches any @samp{-I} directories in the same order as they were
1752 specified (left to right) on the command line.
1755 @section Difference Tables: @option{-K}
1758 @ifclear DIFF-TBL-KLUGE
1759 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1760 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1761 where it can be used to warn when the assembler alters the machine code
1762 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1763 family does not have the addressing limitations that sometimes lead to this
1764 alteration on other platforms.
1767 @ifset DIFF-TBL-KLUGE
1768 @cindex difference tables, warning
1769 @cindex warning for altered difference tables
1770 @command{@value{AS}} sometimes alters the code emitted for directives of the
1771 form @samp{.word @var{sym1}-@var{sym2}}. @xref{Word,,@code{.word}}.
1772 You can use the @samp{-K} option if you want a warning issued when this
1777 @section Include Local Symbols: @option{-L}
1780 @cindex local symbols, retaining in output
1781 Symbols beginning with system-specific local label prefixes, typically
1782 @samp{.L} for ELF systems or @samp{L} for traditional a.out systems, are
1783 called @dfn{local symbols}. @xref{Symbol Names}. Normally you do not see
1784 such symbols when debugging, because they are intended for the use of
1785 programs (like compilers) that compose assembler programs, not for your
1786 notice. Normally both @command{@value{AS}} and @code{@value{LD}} discard
1787 such symbols, so you do not normally debug with them.
1789 This option tells @command{@value{AS}} to retain those local symbols
1790 in the object file. Usually if you do this you also tell the linker
1791 @code{@value{LD}} to preserve those symbols.
1794 @section Configuring listing output: @option{--listing}
1796 The listing feature of the assembler can be enabled via the command line switch
1797 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1798 hex dump of the corresponding locations in the output object file, and displays
1799 them as a listing file. The format of this listing can be controlled by
1800 directives inside the assembler source (i.e., @code{.list} (@pxref{List}),
1801 @code{.title} (@pxref{Title}), @code{.sbttl} (@pxref{Sbttl}),
1802 @code{.psize} (@pxref{Psize}), and
1803 @code{.eject} (@pxref{Eject}) and also by the following switches:
1806 @item --listing-lhs-width=@samp{number}
1807 @kindex --listing-lhs-width
1808 @cindex Width of first line disassembly output
1809 Sets the maximum width, in words, of the first line of the hex byte dump. This
1810 dump appears on the left hand side of the listing output.
1812 @item --listing-lhs-width2=@samp{number}
1813 @kindex --listing-lhs-width2
1814 @cindex Width of continuation lines of disassembly output
1815 Sets the maximum width, in words, of any further lines of the hex byte dump for
1816 a given input source line. If this value is not specified, it defaults to being
1817 the same as the value specified for @samp{--listing-lhs-width}. If neither
1818 switch is used the default is to one.
1820 @item --listing-rhs-width=@samp{number}
1821 @kindex --listing-rhs-width
1822 @cindex Width of source line output
1823 Sets the maximum width, in characters, of the source line that is displayed
1824 alongside the hex dump. The default value for this parameter is 100. The
1825 source line is displayed on the right hand side of the listing output.
1827 @item --listing-cont-lines=@samp{number}
1828 @kindex --listing-cont-lines
1829 @cindex Maximum number of continuation lines
1830 Sets the maximum number of continuation lines of hex dump that will be
1831 displayed for a given single line of source input. The default value is 4.
1835 @section Assemble in MRI Compatibility Mode: @option{-M}
1838 @cindex MRI compatibility mode
1839 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1840 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1841 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1842 configured target) assembler from Microtec Research. The exact nature of the
1843 MRI syntax will not be documented here; see the MRI manuals for more
1844 information. Note in particular that the handling of macros and macro
1845 arguments is somewhat different. The purpose of this option is to permit
1846 assembling existing MRI assembler code using @command{@value{AS}}.
1848 The MRI compatibility is not complete. Certain operations of the MRI assembler
1849 depend upon its object file format, and can not be supported using other object
1850 file formats. Supporting these would require enhancing each object file format
1851 individually. These are:
1854 @item global symbols in common section
1856 The m68k MRI assembler supports common sections which are merged by the linker.
1857 Other object file formats do not support this. @command{@value{AS}} handles
1858 common sections by treating them as a single common symbol. It permits local
1859 symbols to be defined within a common section, but it can not support global
1860 symbols, since it has no way to describe them.
1862 @item complex relocations
1864 The MRI assemblers support relocations against a negated section address, and
1865 relocations which combine the start addresses of two or more sections. These
1866 are not support by other object file formats.
1868 @item @code{END} pseudo-op specifying start address
1870 The MRI @code{END} pseudo-op permits the specification of a start address.
1871 This is not supported by other object file formats. The start address may
1872 instead be specified using the @option{-e} option to the linker, or in a linker
1875 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1877 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1878 name to the output file. This is not supported by other object file formats.
1880 @item @code{ORG} pseudo-op
1882 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1883 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1884 which changes the location within the current section. Absolute sections are
1885 not supported by other object file formats. The address of a section may be
1886 assigned within a linker script.
1889 There are some other features of the MRI assembler which are not supported by
1890 @command{@value{AS}}, typically either because they are difficult or because they
1891 seem of little consequence. Some of these may be supported in future releases.
1895 @item EBCDIC strings
1897 EBCDIC strings are not supported.
1899 @item packed binary coded decimal
1901 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1902 and @code{DCB.P} pseudo-ops are not supported.
1904 @item @code{FEQU} pseudo-op
1906 The m68k @code{FEQU} pseudo-op is not supported.
1908 @item @code{NOOBJ} pseudo-op
1910 The m68k @code{NOOBJ} pseudo-op is not supported.
1912 @item @code{OPT} branch control options
1914 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1915 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1916 relaxes all branches, whether forward or backward, to an appropriate size, so
1917 these options serve no purpose.
1919 @item @code{OPT} list control options
1921 The following m68k @code{OPT} list control options are ignored: @code{C},
1922 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1923 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1925 @item other @code{OPT} options
1927 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1928 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1930 @item @code{OPT} @code{D} option is default
1932 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1933 @code{OPT NOD} may be used to turn it off.
1935 @item @code{XREF} pseudo-op.
1937 The m68k @code{XREF} pseudo-op is ignored.
1939 @item @code{.debug} pseudo-op
1941 The i960 @code{.debug} pseudo-op is not supported.
1943 @item @code{.extended} pseudo-op
1945 The i960 @code{.extended} pseudo-op is not supported.
1947 @item @code{.list} pseudo-op.
1949 The various options of the i960 @code{.list} pseudo-op are not supported.
1951 @item @code{.optimize} pseudo-op
1953 The i960 @code{.optimize} pseudo-op is not supported.
1955 @item @code{.output} pseudo-op
1957 The i960 @code{.output} pseudo-op is not supported.
1959 @item @code{.setreal} pseudo-op
1961 The i960 @code{.setreal} pseudo-op is not supported.
1966 @section Dependency Tracking: @option{--MD}
1969 @cindex dependency tracking
1972 @command{@value{AS}} can generate a dependency file for the file it creates. This
1973 file consists of a single rule suitable for @code{make} describing the
1974 dependencies of the main source file.
1976 The rule is written to the file named in its argument.
1978 This feature is used in the automatic updating of makefiles.
1981 @section Name the Object File: @option{-o}
1984 @cindex naming object file
1985 @cindex object file name
1986 There is always one object file output when you run @command{@value{AS}}. By
1987 default it has the name
1990 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
2004 You use this option (which takes exactly one filename) to give the
2005 object file a different name.
2007 Whatever the object file is called, @command{@value{AS}} overwrites any
2008 existing file of the same name.
2011 @section Join Data and Text Sections: @option{-R}
2014 @cindex data and text sections, joining
2015 @cindex text and data sections, joining
2016 @cindex joining text and data sections
2017 @cindex merging text and data sections
2018 @option{-R} tells @command{@value{AS}} to write the object file as if all
2019 data-section data lives in the text section. This is only done at
2020 the very last moment: your binary data are the same, but data
2021 section parts are relocated differently. The data section part of
2022 your object file is zero bytes long because all its bytes are
2023 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
2025 When you specify @option{-R} it would be possible to generate shorter
2026 address displacements (because we do not have to cross between text and
2027 data section). We refrain from doing this simply for compatibility with
2028 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
2031 When @command{@value{AS}} is configured for COFF or ELF output,
2032 this option is only useful if you use sections named @samp{.text} and
2037 @option{-R} is not supported for any of the HPPA targets. Using
2038 @option{-R} generates a warning from @command{@value{AS}}.
2042 @section Display Assembly Statistics: @option{--statistics}
2044 @kindex --statistics
2045 @cindex statistics, about assembly
2046 @cindex time, total for assembly
2047 @cindex space used, maximum for assembly
2048 Use @samp{--statistics} to display two statistics about the resources used by
2049 @command{@value{AS}}: the maximum amount of space allocated during the assembly
2050 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
2053 @node traditional-format
2054 @section Compatible Output: @option{--traditional-format}
2056 @kindex --traditional-format
2057 For some targets, the output of @command{@value{AS}} is different in some ways
2058 from the output of some existing assembler. This switch requests
2059 @command{@value{AS}} to use the traditional format instead.
2061 For example, it disables the exception frame optimizations which
2062 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
2065 @section Announce Version: @option{-v}
2069 @cindex assembler version
2070 @cindex version of assembler
2071 You can find out what version of as is running by including the
2072 option @samp{-v} (which you can also spell as @samp{-version}) on the
2076 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
2078 @command{@value{AS}} should never give a warning or error message when
2079 assembling compiler output. But programs written by people often
2080 cause @command{@value{AS}} to give a warning that a particular assumption was
2081 made. All such warnings are directed to the standard error file.
2085 @cindex suppressing warnings
2086 @cindex warnings, suppressing
2087 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
2088 This only affects the warning messages: it does not change any particular of
2089 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
2092 @kindex --fatal-warnings
2093 @cindex errors, caused by warnings
2094 @cindex warnings, causing error
2095 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
2096 files that generate warnings to be in error.
2099 @cindex warnings, switching on
2100 You can switch these options off again by specifying @option{--warn}, which
2101 causes warnings to be output as usual.
2104 @section Generate Object File in Spite of Errors: @option{-Z}
2105 @cindex object file, after errors
2106 @cindex errors, continuing after
2107 After an error message, @command{@value{AS}} normally produces no output. If for
2108 some reason you are interested in object file output even after
2109 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
2110 option. If there are any errors, @command{@value{AS}} continues anyways, and
2111 writes an object file after a final warning message of the form @samp{@var{n}
2112 errors, @var{m} warnings, generating bad object file.}
2117 @cindex machine-independent syntax
2118 @cindex syntax, machine-independent
2119 This chapter describes the machine-independent syntax allowed in a
2120 source file. @command{@value{AS}} syntax is similar to what many other
2121 assemblers use; it is inspired by the BSD 4.2
2126 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
2130 * Preprocessing:: Preprocessing
2131 * Whitespace:: Whitespace
2132 * Comments:: Comments
2133 * Symbol Intro:: Symbols
2134 * Statements:: Statements
2135 * Constants:: Constants
2139 @section Preprocessing
2141 @cindex preprocessing
2142 The @command{@value{AS}} internal preprocessor:
2144 @cindex whitespace, removed by preprocessor
2146 adjusts and removes extra whitespace. It leaves one space or tab before
2147 the keywords on a line, and turns any other whitespace on the line into
2150 @cindex comments, removed by preprocessor
2152 removes all comments, replacing them with a single space, or an
2153 appropriate number of newlines.
2155 @cindex constants, converted by preprocessor
2157 converts character constants into the appropriate numeric values.
2160 It does not do macro processing, include file handling, or
2161 anything else you may get from your C compiler's preprocessor. You can
2162 do include file processing with the @code{.include} directive
2163 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
2164 to get other ``CPP'' style preprocessing by giving the input file a
2165 @samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of
2166 Output, gcc.info, Using GNU CC}.
2168 Excess whitespace, comments, and character constants
2169 cannot be used in the portions of the input text that are not
2172 @cindex turning preprocessing on and off
2173 @cindex preprocessing, turning on and off
2176 If the first line of an input file is @code{#NO_APP} or if you use the
2177 @samp{-f} option, whitespace and comments are not removed from the input file.
2178 Within an input file, you can ask for whitespace and comment removal in
2179 specific portions of the by putting a line that says @code{#APP} before the
2180 text that may contain whitespace or comments, and putting a line that says
2181 @code{#NO_APP} after this text. This feature is mainly intend to support
2182 @code{asm} statements in compilers whose output is otherwise free of comments
2189 @dfn{Whitespace} is one or more blanks or tabs, in any order.
2190 Whitespace is used to separate symbols, and to make programs neater for
2191 people to read. Unless within character constants
2192 (@pxref{Characters,,Character Constants}), any whitespace means the same
2193 as exactly one space.
2199 There are two ways of rendering comments to @command{@value{AS}}. In both
2200 cases the comment is equivalent to one space.
2202 Anything from @samp{/*} through the next @samp{*/} is a comment.
2203 This means you may not nest these comments.
2207 The only way to include a newline ('\n') in a comment
2208 is to use this sort of comment.
2211 /* This sort of comment does not nest. */
2214 @cindex line comment character
2215 Anything from the @dfn{line comment} character to the next newline
2216 is considered a comment and is ignored. The line comment character is
2218 @samp{;} on the ARC;
2221 @samp{@@} on the ARM;
2224 @samp{;} for the H8/300 family;
2227 @samp{;} for the HPPA;
2230 @samp{#} on the i386 and x86-64;
2233 @samp{#} on the i960;
2236 @samp{;} for the PDP-11;
2239 @samp{;} for picoJava;
2242 @samp{#} for Motorola PowerPC;
2246 @samp{#} for the Sunplus SCORE;
2250 @samp{#} for IBM S/390;
2254 @samp{!} for the Renesas / SuperH SH;
2257 @samp{!} on the SPARC;
2260 @samp{#} on the ip2k;
2263 @samp{#} on the m32c;
2266 @samp{#} on the m32r;
2269 @samp{|} on the 680x0;
2272 @samp{#} on the 68HC11 and 68HC12;
2275 @samp{#} on the Vax;
2278 @samp{;} for the Z80;
2281 @samp{!} for the Z8000;
2284 @samp{#} on the V850;
2287 @samp{#} for Xtensa systems;
2289 see @ref{Machine Dependencies}. @refill
2290 @c FIXME What about i860?
2293 On some machines there are two different line comment characters. One
2294 character only begins a comment if it is the first non-whitespace character on
2295 a line, while the other always begins a comment.
2299 The V850 assembler also supports a double dash as starting a comment that
2300 extends to the end of the line.
2306 @cindex lines starting with @code{#}
2307 @cindex logical line numbers
2308 To be compatible with past assemblers, lines that begin with @samp{#} have a
2309 special interpretation. Following the @samp{#} should be an absolute
2310 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2311 line. Then a string (@pxref{Strings, ,Strings}) is allowed: if present it is a
2312 new logical file name. The rest of the line, if any, should be whitespace.
2314 If the first non-whitespace characters on the line are not numeric,
2315 the line is ignored. (Just like a comment.)
2318 # This is an ordinary comment.
2319 # 42-6 "new_file_name" # New logical file name
2320 # This is logical line # 36.
2322 This feature is deprecated, and may disappear from future versions
2323 of @command{@value{AS}}.
2328 @cindex characters used in symbols
2329 @ifclear SPECIAL-SYMS
2330 A @dfn{symbol} is one or more characters chosen from the set of all
2331 letters (both upper and lower case), digits and the three characters
2337 A @dfn{symbol} is one or more characters chosen from the set of all
2338 letters (both upper and lower case), digits and the three characters
2339 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2345 On most machines, you can also use @code{$} in symbol names; exceptions
2346 are noted in @ref{Machine Dependencies}.
2348 No symbol may begin with a digit. Case is significant.
2349 There is no length limit: all characters are significant. Symbols are
2350 delimited by characters not in that set, or by the beginning of a file
2351 (since the source program must end with a newline, the end of a file is
2352 not a possible symbol delimiter). @xref{Symbols}.
2353 @cindex length of symbols
2358 @cindex statements, structure of
2359 @cindex line separator character
2360 @cindex statement separator character
2362 @ifclear abnormal-separator
2363 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2364 semicolon (@samp{;}). The newline or semicolon is considered part of
2365 the preceding statement. Newlines and semicolons within character
2366 constants are an exception: they do not end statements.
2368 @ifset abnormal-separator
2370 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2371 point (@samp{!}). The newline or exclamation point is considered part of the
2372 preceding statement. Newlines and exclamation points within character
2373 constants are an exception: they do not end statements.
2376 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2377 H8/300) a dollar sign (@samp{$}); or (for the Renesas-SH) a semicolon
2378 (@samp{;}). The newline or separator character is considered part of
2379 the preceding statement. Newlines and separators within character
2380 constants are an exception: they do not end statements.
2385 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2386 separator character. (The line separator is usually @samp{;}, unless this
2387 conflicts with the comment character; see @ref{Machine Dependencies}.) The
2388 newline or separator character is considered part of the preceding
2389 statement. Newlines and separators within character constants are an
2390 exception: they do not end statements.
2393 @cindex newline, required at file end
2394 @cindex EOF, newline must precede
2395 It is an error to end any statement with end-of-file: the last
2396 character of any input file should be a newline.@refill
2398 An empty statement is allowed, and may include whitespace. It is ignored.
2400 @cindex instructions and directives
2401 @cindex directives and instructions
2402 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2403 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2405 A statement begins with zero or more labels, optionally followed by a
2406 key symbol which determines what kind of statement it is. The key
2407 symbol determines the syntax of the rest of the statement. If the
2408 symbol begins with a dot @samp{.} then the statement is an assembler
2409 directive: typically valid for any computer. If the symbol begins with
2410 a letter the statement is an assembly language @dfn{instruction}: it
2411 assembles into a machine language instruction.
2413 Different versions of @command{@value{AS}} for different computers
2414 recognize different instructions. In fact, the same symbol may
2415 represent a different instruction in a different computer's assembly
2419 @cindex @code{:} (label)
2420 @cindex label (@code{:})
2421 A label is a symbol immediately followed by a colon (@code{:}).
2422 Whitespace before a label or after a colon is permitted, but you may not
2423 have whitespace between a label's symbol and its colon. @xref{Labels}.
2426 For HPPA targets, labels need not be immediately followed by a colon, but
2427 the definition of a label must begin in column zero. This also implies that
2428 only one label may be defined on each line.
2432 label: .directive followed by something
2433 another_label: # This is an empty statement.
2434 instruction operand_1, operand_2, @dots{}
2441 A constant is a number, written so that its value is known by
2442 inspection, without knowing any context. Like this:
2445 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2446 .ascii "Ring the bell\7" # A string constant.
2447 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2448 .float 0f-314159265358979323846264338327\
2449 95028841971.693993751E-40 # - pi, a flonum.
2454 * Characters:: Character Constants
2455 * Numbers:: Number Constants
2459 @subsection Character Constants
2461 @cindex character constants
2462 @cindex constants, character
2463 There are two kinds of character constants. A @dfn{character} stands
2464 for one character in one byte and its value may be used in
2465 numeric expressions. String constants (properly called string
2466 @emph{literals}) are potentially many bytes and their values may not be
2467 used in arithmetic expressions.
2471 * Chars:: Characters
2475 @subsubsection Strings
2477 @cindex string constants
2478 @cindex constants, string
2479 A @dfn{string} is written between double-quotes. It may contain
2480 double-quotes or null characters. The way to get special characters
2481 into a string is to @dfn{escape} these characters: precede them with
2482 a backslash @samp{\} character. For example @samp{\\} represents
2483 one backslash: the first @code{\} is an escape which tells
2484 @command{@value{AS}} to interpret the second character literally as a backslash
2485 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2486 escape character). The complete list of escapes follows.
2488 @cindex escape codes, character
2489 @cindex character escape codes
2492 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2494 @cindex @code{\b} (backspace character)
2495 @cindex backspace (@code{\b})
2497 Mnemonic for backspace; for ASCII this is octal code 010.
2500 @c Mnemonic for EOText; for ASCII this is octal code 004.
2502 @cindex @code{\f} (formfeed character)
2503 @cindex formfeed (@code{\f})
2505 Mnemonic for FormFeed; for ASCII this is octal code 014.
2507 @cindex @code{\n} (newline character)
2508 @cindex newline (@code{\n})
2510 Mnemonic for newline; for ASCII this is octal code 012.
2513 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2515 @cindex @code{\r} (carriage return character)
2516 @cindex carriage return (@code{\r})
2518 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2521 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2522 @c other assemblers.
2524 @cindex @code{\t} (tab)
2525 @cindex tab (@code{\t})
2527 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2530 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2531 @c @item \x @var{digit} @var{digit} @var{digit}
2532 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2534 @cindex @code{\@var{ddd}} (octal character code)
2535 @cindex octal character code (@code{\@var{ddd}})
2536 @item \ @var{digit} @var{digit} @var{digit}
2537 An octal character code. The numeric code is 3 octal digits.
2538 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2539 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2541 @cindex @code{\@var{xd...}} (hex character code)
2542 @cindex hex character code (@code{\@var{xd...}})
2543 @item \@code{x} @var{hex-digits...}
2544 A hex character code. All trailing hex digits are combined. Either upper or
2545 lower case @code{x} works.
2547 @cindex @code{\\} (@samp{\} character)
2548 @cindex backslash (@code{\\})
2550 Represents one @samp{\} character.
2553 @c Represents one @samp{'} (accent acute) character.
2554 @c This is needed in single character literals
2555 @c (@xref{Characters,,Character Constants}.) to represent
2558 @cindex @code{\"} (doublequote character)
2559 @cindex doublequote (@code{\"})
2561 Represents one @samp{"} character. Needed in strings to represent
2562 this character, because an unescaped @samp{"} would end the string.
2564 @item \ @var{anything-else}
2565 Any other character when escaped by @kbd{\} gives a warning, but
2566 assembles as if the @samp{\} was not present. The idea is that if
2567 you used an escape sequence you clearly didn't want the literal
2568 interpretation of the following character. However @command{@value{AS}} has no
2569 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2570 code and warns you of the fact.
2573 Which characters are escapable, and what those escapes represent,
2574 varies widely among assemblers. The current set is what we think
2575 the BSD 4.2 assembler recognizes, and is a subset of what most C
2576 compilers recognize. If you are in doubt, do not use an escape
2580 @subsubsection Characters
2582 @cindex single character constant
2583 @cindex character, single
2584 @cindex constant, single character
2585 A single character may be written as a single quote immediately
2586 followed by that character. The same escapes apply to characters as
2587 to strings. So if you want to write the character backslash, you
2588 must write @kbd{'\\} where the first @code{\} escapes the second
2589 @code{\}. As you can see, the quote is an acute accent, not a
2590 grave accent. A newline
2592 @ifclear abnormal-separator
2593 (or semicolon @samp{;})
2595 @ifset abnormal-separator
2597 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2602 immediately following an acute accent is taken as a literal character
2603 and does not count as the end of a statement. The value of a character
2604 constant in a numeric expression is the machine's byte-wide code for
2605 that character. @command{@value{AS}} assumes your character code is ASCII:
2606 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2609 @subsection Number Constants
2611 @cindex constants, number
2612 @cindex number constants
2613 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2614 are stored in the target machine. @emph{Integers} are numbers that
2615 would fit into an @code{int} in the C language. @emph{Bignums} are
2616 integers, but they are stored in more than 32 bits. @emph{Flonums}
2617 are floating point numbers, described below.
2620 * Integers:: Integers
2625 * Bit Fields:: Bit Fields
2631 @subsubsection Integers
2633 @cindex constants, integer
2635 @cindex binary integers
2636 @cindex integers, binary
2637 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2638 the binary digits @samp{01}.
2640 @cindex octal integers
2641 @cindex integers, octal
2642 An octal integer is @samp{0} followed by zero or more of the octal
2643 digits (@samp{01234567}).
2645 @cindex decimal integers
2646 @cindex integers, decimal
2647 A decimal integer starts with a non-zero digit followed by zero or
2648 more digits (@samp{0123456789}).
2650 @cindex hexadecimal integers
2651 @cindex integers, hexadecimal
2652 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2653 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2655 Integers have the usual values. To denote a negative integer, use
2656 the prefix operator @samp{-} discussed under expressions
2657 (@pxref{Prefix Ops,,Prefix Operators}).
2660 @subsubsection Bignums
2663 @cindex constants, bignum
2664 A @dfn{bignum} has the same syntax and semantics as an integer
2665 except that the number (or its negative) takes more than 32 bits to
2666 represent in binary. The distinction is made because in some places
2667 integers are permitted while bignums are not.
2670 @subsubsection Flonums
2672 @cindex floating point numbers
2673 @cindex constants, floating point
2675 @cindex precision, floating point
2676 A @dfn{flonum} represents a floating point number. The translation is
2677 indirect: a decimal floating point number from the text is converted by
2678 @command{@value{AS}} to a generic binary floating point number of more than
2679 sufficient precision. This generic floating point number is converted
2680 to a particular computer's floating point format (or formats) by a
2681 portion of @command{@value{AS}} specialized to that computer.
2683 A flonum is written by writing (in order)
2688 (@samp{0} is optional on the HPPA.)
2692 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2694 @kbd{e} is recommended. Case is not important.
2696 @c FIXME: verify if flonum syntax really this vague for most cases
2697 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2698 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2701 On the H8/300, Renesas / SuperH SH,
2702 and AMD 29K architectures, the letter must be
2703 one of the letters @samp{DFPRSX} (in upper or lower case).
2705 On the ARC, the letter must be one of the letters @samp{DFRS}
2706 (in upper or lower case).
2708 On the Intel 960 architecture, the letter must be
2709 one of the letters @samp{DFT} (in upper or lower case).
2711 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2715 One of the letters @samp{DFRS} (in upper or lower case).
2718 One of the letters @samp{DFPRSX} (in upper or lower case).
2721 The letter @samp{E} (upper case only).
2724 One of the letters @samp{DFT} (in upper or lower case).
2729 An optional sign: either @samp{+} or @samp{-}.
2732 An optional @dfn{integer part}: zero or more decimal digits.
2735 An optional @dfn{fractional part}: @samp{.} followed by zero
2736 or more decimal digits.
2739 An optional exponent, consisting of:
2743 An @samp{E} or @samp{e}.
2744 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2745 @c principle this can perfectly well be different on different targets.
2747 Optional sign: either @samp{+} or @samp{-}.
2749 One or more decimal digits.
2754 At least one of the integer part or the fractional part must be
2755 present. The floating point number has the usual base-10 value.
2757 @command{@value{AS}} does all processing using integers. Flonums are computed
2758 independently of any floating point hardware in the computer running
2759 @command{@value{AS}}.
2763 @c Bit fields are written as a general facility but are also controlled
2764 @c by a conditional-compilation flag---which is as of now (21mar91)
2765 @c turned on only by the i960 config of GAS.
2767 @subsubsection Bit Fields
2770 @cindex constants, bit field
2771 You can also define numeric constants as @dfn{bit fields}.
2772 Specify two numbers separated by a colon---
2774 @var{mask}:@var{value}
2777 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2780 The resulting number is then packed
2782 @c this conditional paren in case bit fields turned on elsewhere than 960
2783 (in host-dependent byte order)
2785 into a field whose width depends on which assembler directive has the
2786 bit-field as its argument. Overflow (a result from the bitwise and
2787 requiring more binary digits to represent) is not an error; instead,
2788 more constants are generated, of the specified width, beginning with the
2789 least significant digits.@refill
2791 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2792 @code{.short}, and @code{.word} accept bit-field arguments.
2797 @chapter Sections and Relocation
2802 * Secs Background:: Background
2803 * Ld Sections:: Linker Sections
2804 * As Sections:: Assembler Internal Sections
2805 * Sub-Sections:: Sub-Sections
2809 @node Secs Background
2812 Roughly, a section is a range of addresses, with no gaps; all data
2813 ``in'' those addresses is treated the same for some particular purpose.
2814 For example there may be a ``read only'' section.
2816 @cindex linker, and assembler
2817 @cindex assembler, and linker
2818 The linker @code{@value{LD}} reads many object files (partial programs) and
2819 combines their contents to form a runnable program. When @command{@value{AS}}
2820 emits an object file, the partial program is assumed to start at address 0.
2821 @code{@value{LD}} assigns the final addresses for the partial program, so that
2822 different partial programs do not overlap. This is actually an
2823 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2826 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2827 addresses. These blocks slide to their run-time addresses as rigid
2828 units; their length does not change and neither does the order of bytes
2829 within them. Such a rigid unit is called a @emph{section}. Assigning
2830 run-time addresses to sections is called @dfn{relocation}. It includes
2831 the task of adjusting mentions of object-file addresses so they refer to
2832 the proper run-time addresses.
2834 For the H8/300, and for the Renesas / SuperH SH,
2835 @command{@value{AS}} pads sections if needed to
2836 ensure they end on a word (sixteen bit) boundary.
2839 @cindex standard assembler sections
2840 An object file written by @command{@value{AS}} has at least three sections, any
2841 of which may be empty. These are named @dfn{text}, @dfn{data} and
2846 When it generates COFF or ELF output,
2848 @command{@value{AS}} can also generate whatever other named sections you specify
2849 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2850 If you do not use any directives that place output in the @samp{.text}
2851 or @samp{.data} sections, these sections still exist, but are empty.
2856 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2858 @command{@value{AS}} can also generate whatever other named sections you
2859 specify using the @samp{.space} and @samp{.subspace} directives. See
2860 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2861 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2862 assembler directives.
2865 Additionally, @command{@value{AS}} uses different names for the standard
2866 text, data, and bss sections when generating SOM output. Program text
2867 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2868 BSS into @samp{$BSS$}.
2872 Within the object file, the text section starts at address @code{0}, the
2873 data section follows, and the bss section follows the data section.
2876 When generating either SOM or ELF output files on the HPPA, the text
2877 section starts at address @code{0}, the data section at address
2878 @code{0x4000000}, and the bss section follows the data section.
2881 To let @code{@value{LD}} know which data changes when the sections are
2882 relocated, and how to change that data, @command{@value{AS}} also writes to the
2883 object file details of the relocation needed. To perform relocation
2884 @code{@value{LD}} must know, each time an address in the object
2888 Where in the object file is the beginning of this reference to
2891 How long (in bytes) is this reference?
2893 Which section does the address refer to? What is the numeric value of
2895 (@var{address}) @minus{} (@var{start-address of section})?
2898 Is the reference to an address ``Program-Counter relative''?
2901 @cindex addresses, format of
2902 @cindex section-relative addressing
2903 In fact, every address @command{@value{AS}} ever uses is expressed as
2905 (@var{section}) + (@var{offset into section})
2908 Further, most expressions @command{@value{AS}} computes have this section-relative
2911 (For some object formats, such as SOM for the HPPA, some expressions are
2912 symbol-relative instead.)
2915 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2916 @var{N} into section @var{secname}.''
2918 Apart from text, data and bss sections you need to know about the
2919 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2920 addresses in the absolute section remain unchanged. For example, address
2921 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2922 @code{@value{LD}}. Although the linker never arranges two partial programs'
2923 data sections with overlapping addresses after linking, @emph{by definition}
2924 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2925 part of a program is always the same address when the program is running as
2926 address @code{@{absolute@ 239@}} in any other part of the program.
2928 The idea of sections is extended to the @dfn{undefined} section. Any
2929 address whose section is unknown at assembly time is by definition
2930 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2931 Since numbers are always defined, the only way to generate an undefined
2932 address is to mention an undefined symbol. A reference to a named
2933 common block would be such a symbol: its value is unknown at assembly
2934 time so it has section @emph{undefined}.
2936 By analogy the word @emph{section} is used to describe groups of sections in
2937 the linked program. @code{@value{LD}} puts all partial programs' text
2938 sections in contiguous addresses in the linked program. It is
2939 customary to refer to the @emph{text section} of a program, meaning all
2940 the addresses of all partial programs' text sections. Likewise for
2941 data and bss sections.
2943 Some sections are manipulated by @code{@value{LD}}; others are invented for
2944 use of @command{@value{AS}} and have no meaning except during assembly.
2947 @section Linker Sections
2948 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2953 @cindex named sections
2954 @cindex sections, named
2955 @item named sections
2958 @cindex text section
2959 @cindex data section
2963 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2964 separate but equal sections. Anything you can say of one section is
2967 When the program is running, however, it is
2968 customary for the text section to be unalterable. The
2969 text section is often shared among processes: it contains
2970 instructions, constants and the like. The data section of a running
2971 program is usually alterable: for example, C variables would be stored
2972 in the data section.
2977 This section contains zeroed bytes when your program begins running. It
2978 is used to hold uninitialized variables or common storage. The length of
2979 each partial program's bss section is important, but because it starts
2980 out containing zeroed bytes there is no need to store explicit zero
2981 bytes in the object file. The bss section was invented to eliminate
2982 those explicit zeros from object files.
2984 @cindex absolute section
2985 @item absolute section
2986 Address 0 of this section is always ``relocated'' to runtime address 0.
2987 This is useful if you want to refer to an address that @code{@value{LD}} must
2988 not change when relocating. In this sense we speak of absolute
2989 addresses being ``unrelocatable'': they do not change during relocation.
2991 @cindex undefined section
2992 @item undefined section
2993 This ``section'' is a catch-all for address references to objects not in
2994 the preceding sections.
2995 @c FIXME: ref to some other doc on obj-file formats could go here.
2998 @cindex relocation example
2999 An idealized example of three relocatable sections follows.
3001 The example uses the traditional section names @samp{.text} and @samp{.data}.
3003 Memory addresses are on the horizontal axis.
3007 @c END TEXI2ROFF-KILL
3010 partial program # 1: |ttttt|dddd|00|
3017 partial program # 2: |TTT|DDD|000|
3020 +--+---+-----+--+----+---+-----+~~
3021 linked program: | |TTT|ttttt| |dddd|DDD|00000|
3022 +--+---+-----+--+----+---+-----+~~
3024 addresses: 0 @dots{}
3031 \line{\it Partial program \#1: \hfil}
3032 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3033 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
3035 \line{\it Partial program \#2: \hfil}
3036 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
3037 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
3039 \line{\it linked program: \hfil}
3040 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
3041 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
3042 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
3043 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
3045 \line{\it addresses: \hfil}
3049 @c END TEXI2ROFF-KILL
3052 @section Assembler Internal Sections
3054 @cindex internal assembler sections
3055 @cindex sections in messages, internal
3056 These sections are meant only for the internal use of @command{@value{AS}}. They
3057 have no meaning at run-time. You do not really need to know about these
3058 sections for most purposes; but they can be mentioned in @command{@value{AS}}
3059 warning messages, so it might be helpful to have an idea of their
3060 meanings to @command{@value{AS}}. These sections are used to permit the
3061 value of every expression in your assembly language program to be a
3062 section-relative address.
3065 @cindex assembler internal logic error
3066 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
3067 An internal assembler logic error has been found. This means there is a
3068 bug in the assembler.
3070 @cindex expr (internal section)
3072 The assembler stores complex expression internally as combinations of
3073 symbols. When it needs to represent an expression as a symbol, it puts
3074 it in the expr section.
3076 @c FIXME item transfer[t] vector preload
3077 @c FIXME item transfer[t] vector postload
3078 @c FIXME item register
3082 @section Sub-Sections
3084 @cindex numbered subsections
3085 @cindex grouping data
3091 fall into two sections: text and data.
3093 You may have separate groups of
3095 data in named sections
3099 data in named sections
3105 that you want to end up near to each other in the object file, even though they
3106 are not contiguous in the assembler source. @command{@value{AS}} allows you to
3107 use @dfn{subsections} for this purpose. Within each section, there can be
3108 numbered subsections with values from 0 to 8192. Objects assembled into the
3109 same subsection go into the object file together with other objects in the same
3110 subsection. For example, a compiler might want to store constants in the text
3111 section, but might not want to have them interspersed with the program being
3112 assembled. In this case, the compiler could issue a @samp{.text 0} before each
3113 section of code being output, and a @samp{.text 1} before each group of
3114 constants being output.
3116 Subsections are optional. If you do not use subsections, everything
3117 goes in subsection number zero.
3120 Each subsection is zero-padded up to a multiple of four bytes.
3121 (Subsections may be padded a different amount on different flavors
3122 of @command{@value{AS}}.)
3126 On the H8/300 platform, each subsection is zero-padded to a word
3127 boundary (two bytes).
3128 The same is true on the Renesas SH.
3131 @c FIXME section padding (alignment)?
3132 @c Rich Pixley says padding here depends on target obj code format; that
3133 @c doesn't seem particularly useful to say without further elaboration,
3134 @c so for now I say nothing about it. If this is a generic BFD issue,
3135 @c these paragraphs might need to vanish from this manual, and be
3136 @c discussed in BFD chapter of binutils (or some such).
3140 Subsections appear in your object file in numeric order, lowest numbered
3141 to highest. (All this to be compatible with other people's assemblers.)
3142 The object file contains no representation of subsections; @code{@value{LD}} and
3143 other programs that manipulate object files see no trace of them.
3144 They just see all your text subsections as a text section, and all your
3145 data subsections as a data section.
3147 To specify which subsection you want subsequent statements assembled
3148 into, use a numeric argument to specify it, in a @samp{.text
3149 @var{expression}} or a @samp{.data @var{expression}} statement.
3152 When generating COFF output, you
3157 can also use an extra subsection
3158 argument with arbitrary named sections: @samp{.section @var{name},
3163 When generating ELF output, you
3168 can also use the @code{.subsection} directive (@pxref{SubSection})
3169 to specify a subsection: @samp{.subsection @var{expression}}.
3171 @var{Expression} should be an absolute expression
3172 (@pxref{Expressions}). If you just say @samp{.text} then @samp{.text 0}
3173 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
3174 begins in @code{text 0}. For instance:
3176 .text 0 # The default subsection is text 0 anyway.
3177 .ascii "This lives in the first text subsection. *"
3179 .ascii "But this lives in the second text subsection."
3181 .ascii "This lives in the data section,"
3182 .ascii "in the first data subsection."
3184 .ascii "This lives in the first text section,"
3185 .ascii "immediately following the asterisk (*)."
3188 Each section has a @dfn{location counter} incremented by one for every byte
3189 assembled into that section. Because subsections are merely a convenience
3190 restricted to @command{@value{AS}} there is no concept of a subsection location
3191 counter. There is no way to directly manipulate a location counter---but the
3192 @code{.align} directive changes it, and any label definition captures its
3193 current value. The location counter of the section where statements are being
3194 assembled is said to be the @dfn{active} location counter.
3197 @section bss Section
3200 @cindex common variable storage
3201 The bss section is used for local common variable storage.
3202 You may allocate address space in the bss section, but you may
3203 not dictate data to load into it before your program executes. When
3204 your program starts running, all the contents of the bss
3205 section are zeroed bytes.
3207 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
3208 @ref{Lcomm,,@code{.lcomm}}.
3210 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
3211 another form of uninitialized symbol; see @ref{Comm,,@code{.comm}}.
3214 When assembling for a target which supports multiple sections, such as ELF or
3215 COFF, you may switch into the @code{.bss} section and define symbols as usual;
3216 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
3217 section. Typically the section will only contain symbol definitions and
3218 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
3225 Symbols are a central concept: the programmer uses symbols to name
3226 things, the linker uses symbols to link, and the debugger uses symbols
3230 @cindex debuggers, and symbol order
3231 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3232 the same order they were declared. This may break some debuggers.
3237 * Setting Symbols:: Giving Symbols Other Values
3238 * Symbol Names:: Symbol Names
3239 * Dot:: The Special Dot Symbol
3240 * Symbol Attributes:: Symbol Attributes
3247 A @dfn{label} is written as a symbol immediately followed by a colon
3248 @samp{:}. The symbol then represents the current value of the
3249 active location counter, and is, for example, a suitable instruction
3250 operand. You are warned if you use the same symbol to represent two
3251 different locations: the first definition overrides any other
3255 On the HPPA, the usual form for a label need not be immediately followed by a
3256 colon, but instead must start in column zero. Only one label may be defined on
3257 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3258 provides a special directive @code{.label} for defining labels more flexibly.
3261 @node Setting Symbols
3262 @section Giving Symbols Other Values
3264 @cindex assigning values to symbols
3265 @cindex symbol values, assigning
3266 A symbol can be given an arbitrary value by writing a symbol, followed
3267 by an equals sign @samp{=}, followed by an expression
3268 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3269 directive. @xref{Set,,@code{.set}}. In the same way, using a double
3270 equals sign @samp{=}@samp{=} here represents an equivalent of the
3271 @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}.
3274 @section Symbol Names
3276 @cindex symbol names
3277 @cindex names, symbol
3278 @ifclear SPECIAL-SYMS
3279 Symbol names begin with a letter or with one of @samp{._}. On most
3280 machines, you can also use @code{$} in symbol names; exceptions are
3281 noted in @ref{Machine Dependencies}. That character may be followed by any
3282 string of digits, letters, dollar signs (unless otherwise noted for a
3283 particular target machine), and underscores.
3287 Symbol names begin with a letter or with one of @samp{._}. On the
3288 Renesas SH you can also use @code{$} in symbol names. That
3289 character may be followed by any string of digits, letters, dollar signs (save
3290 on the H8/300), and underscores.
3294 Case of letters is significant: @code{foo} is a different symbol name
3297 Each symbol has exactly one name. Each name in an assembly language program
3298 refers to exactly one symbol. You may use that symbol name any number of times
3301 @subheading Local Symbol Names
3303 @cindex local symbol names
3304 @cindex symbol names, local
3305 A local symbol is any symbol beginning with certain local label prefixes.
3306 By default, the local label prefix is @samp{.L} for ELF systems or
3307 @samp{L} for traditional a.out systems, but each target may have its own
3308 set of local label prefixes.
3310 On the HPPA local symbols begin with @samp{L$}.
3313 Local symbols are defined and used within the assembler, but they are
3314 normally not saved in object files. Thus, they are not visible when debugging.
3315 You may use the @samp{-L} option (@pxref{L, ,Include Local Symbols:
3316 @option{-L}}) to retain the local symbols in the object files.
3318 @subheading Local Labels
3320 @cindex local labels
3321 @cindex temporary symbol names
3322 @cindex symbol names, temporary
3323 Local labels help compilers and programmers use names temporarily.
3324 They create symbols which are guaranteed to be unique over the entire scope of
3325 the input source code and which can be referred to by a simple notation.
3326 To define a local label, write a label of the form @samp{@b{N}:} (where @b{N}
3327 represents any positive integer). To refer to the most recent previous
3328 definition of that label write @samp{@b{N}b}, using the same number as when
3329 you defined the label. To refer to the next definition of a local label, write
3330 @samp{@b{N}f}---the @samp{b} stands for ``backwards'' and the @samp{f} stands
3333 There is no restriction on how you can use these labels, and you can reuse them
3334 too. So that it is possible to repeatedly define the same local label (using
3335 the same number @samp{@b{N}}), although you can only refer to the most recently
3336 defined local label of that number (for a backwards reference) or the next
3337 definition of a specific local label for a forward reference. It is also worth
3338 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3339 implemented in a slightly more efficient manner than the others.
3350 Which is the equivalent of:
3353 label_1: branch label_3
3354 label_2: branch label_1
3355 label_3: branch label_4
3356 label_4: branch label_3
3359 Local label names are only a notational device. They are immediately
3360 transformed into more conventional symbol names before the assembler uses them.
3361 The symbol names are stored in the symbol table, appear in error messages, and
3362 are optionally emitted to the object file. The names are constructed using
3366 @item @emph{local label prefix}
3367 All local symbols begin with the system-specific local label prefix.
3368 Normally both @command{@value{AS}} and @code{@value{LD}} forget symbols
3369 that start with the local label prefix. These labels are
3370 used for symbols you are never intended to see. If you use the
3371 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3372 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3373 you may use them in debugging.
3376 This is the number that was used in the local label definition. So if the
3377 label is written @samp{55:} then the number is @samp{55}.
3380 This unusual character is included so you do not accidentally invent a symbol
3381 of the same name. The character has ASCII value of @samp{\002} (control-B).
3383 @item @emph{ordinal number}
3384 This is a serial number to keep the labels distinct. The first definition of
3385 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3386 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3387 the number @samp{1} and its 15th definition gets @samp{15} as well.
3390 So for example, the first @code{1:} may be named @code{.L1@kbd{C-B}1}, and
3391 the 44th @code{3:} may be named @code{.L3@kbd{C-B}44}.
3393 @subheading Dollar Local Labels
3394 @cindex dollar local symbols
3396 @code{@value{AS}} also supports an even more local form of local labels called
3397 dollar labels. These labels go out of scope (i.e., they become undefined) as
3398 soon as a non-local label is defined. Thus they remain valid for only a small
3399 region of the input source code. Normal local labels, by contrast, remain in
3400 scope for the entire file, or until they are redefined by another occurrence of
3401 the same local label.
3403 Dollar labels are defined in exactly the same way as ordinary local labels,
3404 except that they have a dollar sign suffix to their numeric value, e.g.,
3407 They can also be distinguished from ordinary local labels by their transformed
3408 names which use ASCII character @samp{\001} (control-A) as the magic character
3409 to distinguish them from ordinary labels. For example, the fifth definition of
3410 @samp{6$} may be named @samp{.L6@kbd{C-A}5}.
3413 @section The Special Dot Symbol
3415 @cindex dot (symbol)
3416 @cindex @code{.} (symbol)
3417 @cindex current address
3418 @cindex location counter
3419 The special symbol @samp{.} refers to the current address that
3420 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3421 .long .} defines @code{melvin} to contain its own address.
3422 Assigning a value to @code{.} is treated the same as a @code{.org}
3424 @ifclear no-space-dir
3425 Thus, the expression @samp{.=.+4} is the same as saying
3429 @node Symbol Attributes
3430 @section Symbol Attributes
3432 @cindex symbol attributes
3433 @cindex attributes, symbol
3434 Every symbol has, as well as its name, the attributes ``Value'' and
3435 ``Type''. Depending on output format, symbols can also have auxiliary
3438 The detailed definitions are in @file{a.out.h}.
3441 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3442 all these attributes, and probably won't warn you. This makes the
3443 symbol an externally defined symbol, which is generally what you
3447 * Symbol Value:: Value
3448 * Symbol Type:: Type
3451 * a.out Symbols:: Symbol Attributes: @code{a.out}
3455 * a.out Symbols:: Symbol Attributes: @code{a.out}
3458 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3463 * COFF Symbols:: Symbol Attributes for COFF
3466 * SOM Symbols:: Symbol Attributes for SOM
3473 @cindex value of a symbol
3474 @cindex symbol value
3475 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3476 location in the text, data, bss or absolute sections the value is the
3477 number of addresses from the start of that section to the label.
3478 Naturally for text, data and bss sections the value of a symbol changes
3479 as @code{@value{LD}} changes section base addresses during linking. Absolute
3480 symbols' values do not change during linking: that is why they are
3483 The value of an undefined symbol is treated in a special way. If it is
3484 0 then the symbol is not defined in this assembler source file, and
3485 @code{@value{LD}} tries to determine its value from other files linked into the
3486 same program. You make this kind of symbol simply by mentioning a symbol
3487 name without defining it. A non-zero value represents a @code{.comm}
3488 common declaration. The value is how much common storage to reserve, in
3489 bytes (addresses). The symbol refers to the first address of the
3495 @cindex type of a symbol
3497 The type attribute of a symbol contains relocation (section)
3498 information, any flag settings indicating that a symbol is external, and
3499 (optionally), other information for linkers and debuggers. The exact
3500 format depends on the object-code output format in use.
3505 @c The following avoids a "widow" subsection title. @group would be
3506 @c better if it were available outside examples.
3509 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3511 @cindex @code{b.out} symbol attributes
3512 @cindex symbol attributes, @code{b.out}
3513 These symbol attributes appear only when @command{@value{AS}} is configured for
3514 one of the Berkeley-descended object output formats---@code{a.out} or
3520 @subsection Symbol Attributes: @code{a.out}
3522 @cindex @code{a.out} symbol attributes
3523 @cindex symbol attributes, @code{a.out}
3529 @subsection Symbol Attributes: @code{a.out}
3531 @cindex @code{a.out} symbol attributes
3532 @cindex symbol attributes, @code{a.out}
3536 * Symbol Desc:: Descriptor
3537 * Symbol Other:: Other
3541 @subsubsection Descriptor
3543 @cindex descriptor, of @code{a.out} symbol
3544 This is an arbitrary 16-bit value. You may establish a symbol's
3545 descriptor value by using a @code{.desc} statement
3546 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3547 @command{@value{AS}}.
3550 @subsubsection Other
3552 @cindex other attribute, of @code{a.out} symbol
3553 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3558 @subsection Symbol Attributes for COFF
3560 @cindex COFF symbol attributes
3561 @cindex symbol attributes, COFF
3563 The COFF format supports a multitude of auxiliary symbol attributes;
3564 like the primary symbol attributes, they are set between @code{.def} and
3565 @code{.endef} directives.
3567 @subsubsection Primary Attributes
3569 @cindex primary attributes, COFF symbols
3570 The symbol name is set with @code{.def}; the value and type,
3571 respectively, with @code{.val} and @code{.type}.
3573 @subsubsection Auxiliary Attributes
3575 @cindex auxiliary attributes, COFF symbols
3576 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3577 @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol
3578 table information for COFF.
3583 @subsection Symbol Attributes for SOM
3585 @cindex SOM symbol attributes
3586 @cindex symbol attributes, SOM
3588 The SOM format for the HPPA supports a multitude of symbol attributes set with
3589 the @code{.EXPORT} and @code{.IMPORT} directives.
3591 The attributes are described in @cite{HP9000 Series 800 Assembly
3592 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3593 @code{EXPORT} assembler directive documentation.
3597 @chapter Expressions
3601 @cindex numeric values
3602 An @dfn{expression} specifies an address or numeric value.
3603 Whitespace may precede and/or follow an expression.
3605 The result of an expression must be an absolute number, or else an offset into
3606 a particular section. If an expression is not absolute, and there is not
3607 enough information when @command{@value{AS}} sees the expression to know its
3608 section, a second pass over the source program might be necessary to interpret
3609 the expression---but the second pass is currently not implemented.
3610 @command{@value{AS}} aborts with an error message in this situation.
3613 * Empty Exprs:: Empty Expressions
3614 * Integer Exprs:: Integer Expressions
3618 @section Empty Expressions
3620 @cindex empty expressions
3621 @cindex expressions, empty
3622 An empty expression has no value: it is just whitespace or null.
3623 Wherever an absolute expression is required, you may omit the
3624 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3625 is compatible with other assemblers.
3628 @section Integer Expressions
3630 @cindex integer expressions
3631 @cindex expressions, integer
3632 An @dfn{integer expression} is one or more @emph{arguments} delimited
3633 by @emph{operators}.
3636 * Arguments:: Arguments
3637 * Operators:: Operators
3638 * Prefix Ops:: Prefix Operators
3639 * Infix Ops:: Infix Operators
3643 @subsection Arguments
3645 @cindex expression arguments
3646 @cindex arguments in expressions
3647 @cindex operands in expressions
3648 @cindex arithmetic operands
3649 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3650 contexts arguments are sometimes called ``arithmetic operands''. In
3651 this manual, to avoid confusing them with the ``instruction operands'' of
3652 the machine language, we use the term ``argument'' to refer to parts of
3653 expressions only, reserving the word ``operand'' to refer only to machine
3654 instruction operands.
3656 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3657 @var{section} is one of text, data, bss, absolute,
3658 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3661 Numbers are usually integers.
3663 A number can be a flonum or bignum. In this case, you are warned
3664 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3665 these 32 bits are an integer. You may write integer-manipulating
3666 instructions that act on exotic constants, compatible with other
3669 @cindex subexpressions
3670 Subexpressions are a left parenthesis @samp{(} followed by an integer
3671 expression, followed by a right parenthesis @samp{)}; or a prefix
3672 operator followed by an argument.
3675 @subsection Operators
3677 @cindex operators, in expressions
3678 @cindex arithmetic functions
3679 @cindex functions, in expressions
3680 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3681 operators are followed by an argument. Infix operators appear
3682 between their arguments. Operators may be preceded and/or followed by
3686 @subsection Prefix Operator
3688 @cindex prefix operators
3689 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3690 one argument, which must be absolute.
3692 @c the tex/end tex stuff surrounding this small table is meant to make
3693 @c it align, on the printed page, with the similar table in the next
3694 @c section (which is inside an enumerate).
3696 \global\advance\leftskip by \itemindent
3701 @dfn{Negation}. Two's complement negation.
3703 @dfn{Complementation}. Bitwise not.
3707 \global\advance\leftskip by -\itemindent
3711 @subsection Infix Operators
3713 @cindex infix operators
3714 @cindex operators, permitted arguments
3715 @dfn{Infix operators} take two arguments, one on either side. Operators
3716 have precedence, but operations with equal precedence are performed left
3717 to right. Apart from @code{+} or @option{-}, both arguments must be
3718 absolute, and the result is absolute.
3721 @cindex operator precedence
3722 @cindex precedence of operators
3729 @dfn{Multiplication}.
3732 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3738 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3741 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3745 Intermediate precedence
3750 @dfn{Bitwise Inclusive Or}.
3756 @dfn{Bitwise Exclusive Or}.
3759 @dfn{Bitwise Or Not}.
3766 @cindex addition, permitted arguments
3767 @cindex plus, permitted arguments
3768 @cindex arguments for addition
3770 @dfn{Addition}. If either argument is absolute, the result has the section of
3771 the other argument. You may not add together arguments from different
3774 @cindex subtraction, permitted arguments
3775 @cindex minus, permitted arguments
3776 @cindex arguments for subtraction
3778 @dfn{Subtraction}. If the right argument is absolute, the
3779 result has the section of the left argument.
3780 If both arguments are in the same section, the result is absolute.
3781 You may not subtract arguments from different sections.
3782 @c FIXME is there still something useful to say about undefined - undefined ?
3784 @cindex comparison expressions
3785 @cindex expressions, comparison
3790 @dfn{Is Not Equal To}
3794 @dfn{Is Greater Than}
3796 @dfn{Is Greater Than Or Equal To}
3798 @dfn{Is Less Than Or Equal To}
3800 The comparison operators can be used as infix operators. A true results has a
3801 value of -1 whereas a false result has a value of 0. Note, these operators
3802 perform signed comparisons.
3805 @item Lowest Precedence
3814 These two logical operations can be used to combine the results of sub
3815 expressions. Note, unlike the comparison operators a true result returns a
3816 value of 1 but a false results does still return 0. Also note that the logical
3817 or operator has a slightly lower precedence than logical and.
3822 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3823 address; you can only have a defined section in one of the two arguments.
3826 @chapter Assembler Directives
3828 @cindex directives, machine independent
3829 @cindex pseudo-ops, machine independent
3830 @cindex machine independent directives
3831 All assembler directives have names that begin with a period (@samp{.}).
3832 The rest of the name is letters, usually in lower case.
3834 This chapter discusses directives that are available regardless of the
3835 target machine configuration for the @sc{gnu} assembler.
3837 Some machine configurations provide additional directives.
3838 @xref{Machine Dependencies}.
3841 @ifset machine-directives
3842 @xref{Machine Dependencies}, for additional directives.
3847 * Abort:: @code{.abort}
3849 * ABORT (COFF):: @code{.ABORT}
3852 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3853 * Altmacro:: @code{.altmacro}
3854 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3855 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3856 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3857 * Byte:: @code{.byte @var{expressions}}
3858 * CFI directives:: @code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
3859 * Comm:: @code{.comm @var{symbol} , @var{length} }
3860 * Data:: @code{.data @var{subsection}}
3862 * Def:: @code{.def @var{name}}
3865 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3871 * Double:: @code{.double @var{flonums}}
3872 * Eject:: @code{.eject}
3873 * Else:: @code{.else}
3874 * Elseif:: @code{.elseif}
3877 * Endef:: @code{.endef}
3880 * Endfunc:: @code{.endfunc}
3881 * Endif:: @code{.endif}
3882 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3883 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3884 * Eqv:: @code{.eqv @var{symbol}, @var{expression}}
3886 * Error:: @code{.error @var{string}}
3887 * Exitm:: @code{.exitm}
3888 * Extern:: @code{.extern}
3889 * Fail:: @code{.fail}
3890 * File:: @code{.file}
3891 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3892 * Float:: @code{.float @var{flonums}}
3893 * Func:: @code{.func}
3894 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3896 * Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
3897 * Hidden:: @code{.hidden @var{names}}
3900 * hword:: @code{.hword @var{expressions}}
3901 * Ident:: @code{.ident}
3902 * If:: @code{.if @var{absolute expression}}
3903 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3904 * Include:: @code{.include "@var{file}"}
3905 * Int:: @code{.int @var{expressions}}
3907 * Internal:: @code{.internal @var{names}}
3910 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3911 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3912 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3913 * Lflags:: @code{.lflags}
3914 @ifclear no-line-dir
3915 * Line:: @code{.line @var{line-number}}
3918 * Linkonce:: @code{.linkonce [@var{type}]}
3919 * List:: @code{.list}
3920 * Ln:: @code{.ln @var{line-number}}
3921 * Loc:: @code{.loc @var{fileno} @var{lineno}}
3922 * Loc_mark_labels:: @code{.loc_mark_labels @var{enable}}
3924 * Local:: @code{.local @var{names}}
3927 * Long:: @code{.long @var{expressions}}
3929 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3932 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3933 * MRI:: @code{.mri @var{val}}
3934 * Noaltmacro:: @code{.noaltmacro}
3935 * Nolist:: @code{.nolist}
3936 * Octa:: @code{.octa @var{bignums}}
3937 * Org:: @code{.org @var{new-lc}, @var{fill}}
3938 * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3940 * PopSection:: @code{.popsection}
3941 * Previous:: @code{.previous}
3944 * Print:: @code{.print @var{string}}
3946 * Protected:: @code{.protected @var{names}}
3949 * Psize:: @code{.psize @var{lines}, @var{columns}}
3950 * Purgem:: @code{.purgem @var{name}}
3952 * PushSection:: @code{.pushsection @var{name}}
3955 * Quad:: @code{.quad @var{bignums}}
3956 * Reloc:: @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
3957 * Rept:: @code{.rept @var{count}}
3958 * Sbttl:: @code{.sbttl "@var{subheading}"}
3960 * Scl:: @code{.scl @var{class}}
3963 * Section:: @code{.section @var{name}[, @var{flags}]}
3966 * Set:: @code{.set @var{symbol}, @var{expression}}
3967 * Short:: @code{.short @var{expressions}}
3968 * Single:: @code{.single @var{flonums}}
3970 * Size:: @code{.size [@var{name} , @var{expression}]}
3972 @ifclear no-space-dir
3973 * Skip:: @code{.skip @var{size} , @var{fill}}
3976 * Sleb128:: @code{.sleb128 @var{expressions}}
3977 @ifclear no-space-dir
3978 * Space:: @code{.space @var{size} , @var{fill}}
3981 * Stab:: @code{.stabd, .stabn, .stabs}
3984 * String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
3985 * Struct:: @code{.struct @var{expression}}
3987 * SubSection:: @code{.subsection}
3988 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3992 * Tag:: @code{.tag @var{structname}}
3995 * Text:: @code{.text @var{subsection}}
3996 * Title:: @code{.title "@var{heading}"}
3998 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
4001 * Uleb128:: @code{.uleb128 @var{expressions}}
4003 * Val:: @code{.val @var{addr}}
4007 * Version:: @code{.version "@var{string}"}
4008 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
4009 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
4012 * Warning:: @code{.warning @var{string}}
4013 * Weak:: @code{.weak @var{names}}
4014 * Weakref:: @code{.weakref @var{alias}, @var{symbol}}
4015 * Word:: @code{.word @var{expressions}}
4016 * Deprecated:: Deprecated Directives
4020 @section @code{.abort}
4022 @cindex @code{abort} directive
4023 @cindex stopping the assembly
4024 This directive stops the assembly immediately. It is for
4025 compatibility with other assemblers. The original idea was that the
4026 assembly language source would be piped into the assembler. If the sender
4027 of the source quit, it could use this directive tells @command{@value{AS}} to
4028 quit also. One day @code{.abort} will not be supported.
4032 @section @code{.ABORT} (COFF)
4034 @cindex @code{ABORT} directive
4035 When producing COFF output, @command{@value{AS}} accepts this directive as a
4036 synonym for @samp{.abort}.
4039 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
4045 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4047 @cindex padding the location counter
4048 @cindex @code{align} directive
4049 Pad the location counter (in the current subsection) to a particular storage
4050 boundary. The first expression (which must be absolute) is the alignment
4051 required, as described below.
4053 The second expression (also absolute) gives the fill value to be stored in the
4054 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4055 padding bytes are normally zero. However, on some systems, if the section is
4056 marked as containing code and the fill value is omitted, the space is filled
4057 with no-op instructions.
4059 The third expression is also absolute, and is also optional. If it is present,
4060 it is the maximum number of bytes that should be skipped by this alignment
4061 directive. If doing the alignment would require skipping more bytes than the
4062 specified maximum, then the alignment is not done at all. You can omit the
4063 fill value (the second argument) entirely by simply using two commas after the
4064 required alignment; this can be useful if you want the alignment to be filled
4065 with no-op instructions when appropriate.
4067 The way the required alignment is specified varies from system to system.
4068 For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32,
4069 s390, sparc, tic4x, tic80 and xtensa, the first expression is the
4070 alignment request in bytes. For example @samp{.align 8} advances
4071 the location counter until it is a multiple of 8. If the location counter
4072 is already a multiple of 8, no change is needed. For the tic54x, the
4073 first expression is the alignment request in words.
4075 For other systems, including ppc, i386 using a.out format, arm and
4076 strongarm, it is the
4077 number of low-order zero bits the location counter must have after
4078 advancement. For example @samp{.align 3} advances the location
4079 counter until it a multiple of 8. If the location counter is already a
4080 multiple of 8, no change is needed.
4082 This inconsistency is due to the different behaviors of the various
4083 native assemblers for these systems which GAS must emulate.
4084 GAS also provides @code{.balign} and @code{.p2align} directives,
4085 described later, which have a consistent behavior across all
4086 architectures (but are specific to GAS).
4089 @section @code{.altmacro}
4090 Enable alternate macro mode, enabling:
4093 @item LOCAL @var{name} [ , @dots{} ]
4094 One additional directive, @code{LOCAL}, is available. It is used to
4095 generate a string replacement for each of the @var{name} arguments, and
4096 replace any instances of @var{name} in each macro expansion. The
4097 replacement string is unique in the assembly, and different for each
4098 separate macro expansion. @code{LOCAL} allows you to write macros that
4099 define symbols, without fear of conflict between separate macro expansions.
4101 @item String delimiters
4102 You can write strings delimited in these other ways besides
4103 @code{"@var{string}"}:
4106 @item '@var{string}'
4107 You can delimit strings with single-quote characters.
4109 @item <@var{string}>
4110 You can delimit strings with matching angle brackets.
4113 @item single-character string escape
4114 To include any single character literally in a string (even if the
4115 character would otherwise have some special meaning), you can prefix the
4116 character with @samp{!} (an exclamation mark). For example, you can
4117 write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}.
4119 @item Expression results as strings
4120 You can write @samp{%@var{expr}} to evaluate the expression @var{expr}
4121 and use the result as a string.
4125 @section @code{.ascii "@var{string}"}@dots{}
4127 @cindex @code{ascii} directive
4128 @cindex string literals
4129 @code{.ascii} expects zero or more string literals (@pxref{Strings})
4130 separated by commas. It assembles each string (with no automatic
4131 trailing zero byte) into consecutive addresses.
4134 @section @code{.asciz "@var{string}"}@dots{}
4136 @cindex @code{asciz} directive
4137 @cindex zero-terminated strings
4138 @cindex null-terminated strings
4139 @code{.asciz} is just like @code{.ascii}, but each string is followed by
4140 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
4143 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4145 @cindex padding the location counter given number of bytes
4146 @cindex @code{balign} directive
4147 Pad the location counter (in the current subsection) to a particular
4148 storage boundary. The first expression (which must be absolute) is the
4149 alignment request in bytes. For example @samp{.balign 8} advances
4150 the location counter until it is a multiple of 8. If the location counter
4151 is already a multiple of 8, no change is needed.
4153 The second expression (also absolute) gives the fill value to be stored in the
4154 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4155 padding bytes are normally zero. However, on some systems, if the section is
4156 marked as containing code and the fill value is omitted, the space is filled
4157 with no-op instructions.
4159 The third expression is also absolute, and is also optional. If it is present,
4160 it is the maximum number of bytes that should be skipped by this alignment
4161 directive. If doing the alignment would require skipping more bytes than the
4162 specified maximum, then the alignment is not done at all. You can omit the
4163 fill value (the second argument) entirely by simply using two commas after the
4164 required alignment; this can be useful if you want the alignment to be filled
4165 with no-op instructions when appropriate.
4167 @cindex @code{balignw} directive
4168 @cindex @code{balignl} directive
4169 The @code{.balignw} and @code{.balignl} directives are variants of the
4170 @code{.balign} directive. The @code{.balignw} directive treats the fill
4171 pattern as a two byte word value. The @code{.balignl} directives treats the
4172 fill pattern as a four byte longword value. For example, @code{.balignw
4173 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4174 filled in with the value 0x368d (the exact placement of the bytes depends upon
4175 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4179 @section @code{.byte @var{expressions}}
4181 @cindex @code{byte} directive
4182 @cindex integers, one byte
4183 @code{.byte} expects zero or more expressions, separated by commas.
4184 Each expression is assembled into the next byte.
4186 @node CFI directives
4187 @section @code{.cfi_startproc [simple]}
4188 @cindex @code{cfi_startproc} directive
4189 @code{.cfi_startproc} is used at the beginning of each function that
4190 should have an entry in @code{.eh_frame}. It initializes some internal
4191 data structures. Don't forget to close the function by
4192 @code{.cfi_endproc}.
4194 Unless @code{.cfi_startproc} is used along with parameter @code{simple}
4195 it also emits some architecture dependent initial CFI instructions.
4197 @section @code{.cfi_endproc}
4198 @cindex @code{cfi_endproc} directive
4199 @code{.cfi_endproc} is used at the end of a function where it closes its
4200 unwind entry previously opened by
4201 @code{.cfi_startproc}, and emits it to @code{.eh_frame}.
4203 @section @code{.cfi_personality @var{encoding} [, @var{exp}]}
4204 @code{.cfi_personality} defines personality routine and its encoding.
4205 @var{encoding} must be a constant determining how the personality
4206 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4207 argument is not present, otherwise second argument should be
4208 a constant or a symbol name. When using indirect encodings,
4209 the symbol provided should be the location where personality
4210 can be loaded from, not the personality routine itself.
4211 The default after @code{.cfi_startproc} is @code{.cfi_personality 0xff},
4212 no personality routine.
4214 @section @code{.cfi_lsda @var{encoding} [, @var{exp}]}
4215 @code{.cfi_lsda} defines LSDA and its encoding.
4216 @var{encoding} must be a constant determining how the LSDA
4217 should be encoded. If it is 255 (@code{DW_EH_PE_omit}), second
4218 argument is not present, otherwise second argument should be a constant
4219 or a symbol name. The default after @code{.cfi_startproc} is @code{.cfi_lsda 0xff},
4222 @section @code{.cfi_def_cfa @var{register}, @var{offset}}
4223 @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take
4224 address from @var{register} and add @var{offset} to it}.
4226 @section @code{.cfi_def_cfa_register @var{register}}
4227 @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From
4228 now on @var{register} will be used instead of the old one. Offset
4231 @section @code{.cfi_def_cfa_offset @var{offset}}
4232 @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register
4233 remains the same, but @var{offset} is new. Note that it is the
4234 absolute offset that will be added to a defined register to compute
4237 @section @code{.cfi_adjust_cfa_offset @var{offset}}
4238 Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative
4239 value that is added/substracted from the previous offset.
4241 @section @code{.cfi_offset @var{register}, @var{offset}}
4242 Previous value of @var{register} is saved at offset @var{offset} from
4245 @section @code{.cfi_rel_offset @var{register}, @var{offset}}
4246 Previous value of @var{register} is saved at offset @var{offset} from
4247 the current CFA register. This is transformed to @code{.cfi_offset}
4248 using the known displacement of the CFA register from the CFA.
4249 This is often easier to use, because the number will match the
4250 code it's annotating.
4252 @section @code{.cfi_register @var{register1}, @var{register2}}
4253 Previous value of @var{register1} is saved in register @var{register2}.
4255 @section @code{.cfi_restore @var{register}}
4256 @code{.cfi_restore} says that the rule for @var{register} is now the
4257 same as it was at the beginning of the function, after all initial
4258 instruction added by @code{.cfi_startproc} were executed.
4260 @section @code{.cfi_undefined @var{register}}
4261 From now on the previous value of @var{register} can't be restored anymore.
4263 @section @code{.cfi_same_value @var{register}}
4264 Current value of @var{register} is the same like in the previous frame,
4265 i.e. no restoration needed.
4267 @section @code{.cfi_remember_state},
4268 First save all current rules for all registers by @code{.cfi_remember_state},
4269 then totally screw them up by subsequent @code{.cfi_*} directives and when
4270 everything is hopelessly bad, use @code{.cfi_restore_state} to restore
4271 the previous saved state.
4273 @section @code{.cfi_return_column @var{register}}
4274 Change return column @var{register}, i.e. the return address is either
4275 directly in @var{register} or can be accessed by rules for @var{register}.
4277 @section @code{.cfi_signal_frame}
4278 Mark current function as signal trampoline.
4280 @section @code{.cfi_window_save}
4281 SPARC register window has been saved.
4283 @section @code{.cfi_escape} @var{expression}[, @dots{}]
4284 Allows the user to add arbitrary bytes to the unwind info. One
4285 might use this to add OS-specific CFI opcodes, or generic CFI
4286 opcodes that GAS does not yet support.
4288 @section @code{.cfi_val_encoded_addr @var{register}, @var{encoding}, @var{label}}
4289 The current value of @var{register} is @var{label}. The value of @var{label}
4290 will be encoded in the output file according to @var{encoding}; see the
4291 description of @code{.cfi_personality} for details on this encoding.
4293 The usefulness of equating a register to a fixed label is probably
4294 limited to the return address register. Here, it can be useful to
4295 mark a code segment that has only one return address which is reached
4296 by a direct branch and no copy of the return address exists in memory
4297 or another register.
4300 @section @code{.comm @var{symbol} , @var{length} }
4302 @cindex @code{comm} directive
4303 @cindex symbol, common
4304 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
4305 common symbol in one object file may be merged with a defined or common symbol
4306 of the same name in another object file. If @code{@value{LD}} does not see a
4307 definition for the symbol--just one or more common symbols--then it will
4308 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
4309 absolute expression. If @code{@value{LD}} sees multiple common symbols with
4310 the same name, and they do not all have the same size, it will allocate space
4311 using the largest size.
4314 When using ELF, the @code{.comm} directive takes an optional third argument.
4315 This is the desired alignment of the symbol, specified as a byte boundary (for
4316 example, an alignment of 16 means that the least significant 4 bits of the
4317 address should be zero). The alignment must be an absolute expression, and it
4318 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
4319 for the common symbol, it will use the alignment when placing the symbol. If
4320 no alignment is specified, @command{@value{AS}} will set the alignment to the
4321 largest power of two less than or equal to the size of the symbol, up to a
4326 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
4327 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
4331 @section @code{.data @var{subsection}}
4333 @cindex @code{data} directive
4334 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
4335 end of the data subsection numbered @var{subsection} (which is an
4336 absolute expression). If @var{subsection} is omitted, it defaults
4341 @section @code{.def @var{name}}
4343 @cindex @code{def} directive
4344 @cindex COFF symbols, debugging
4345 @cindex debugging COFF symbols
4346 Begin defining debugging information for a symbol @var{name}; the
4347 definition extends until the @code{.endef} directive is encountered.
4350 This directive is only observed when @command{@value{AS}} is configured for COFF
4351 format output; when producing @code{b.out}, @samp{.def} is recognized,
4358 @section @code{.desc @var{symbol}, @var{abs-expression}}
4360 @cindex @code{desc} directive
4361 @cindex COFF symbol descriptor
4362 @cindex symbol descriptor, COFF
4363 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
4364 to the low 16 bits of an absolute expression.
4367 The @samp{.desc} directive is not available when @command{@value{AS}} is
4368 configured for COFF output; it is only for @code{a.out} or @code{b.out}
4369 object format. For the sake of compatibility, @command{@value{AS}} accepts
4370 it, but produces no output, when configured for COFF.
4376 @section @code{.dim}
4378 @cindex @code{dim} directive
4379 @cindex COFF auxiliary symbol information
4380 @cindex auxiliary symbol information, COFF
4381 This directive is generated by compilers to include auxiliary debugging
4382 information in the symbol table. It is only permitted inside
4383 @code{.def}/@code{.endef} pairs.
4386 @samp{.dim} is only meaningful when generating COFF format output; when
4387 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
4393 @section @code{.double @var{flonums}}
4395 @cindex @code{double} directive
4396 @cindex floating point numbers (double)
4397 @code{.double} expects zero or more flonums, separated by commas. It
4398 assembles floating point numbers.
4400 The exact kind of floating point numbers emitted depends on how
4401 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
4405 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
4406 in @sc{ieee} format.
4411 @section @code{.eject}
4413 @cindex @code{eject} directive
4414 @cindex new page, in listings
4415 @cindex page, in listings
4416 @cindex listing control: new page
4417 Force a page break at this point, when generating assembly listings.
4420 @section @code{.else}
4422 @cindex @code{else} directive
4423 @code{.else} is part of the @command{@value{AS}} support for conditional
4424 assembly; see @ref{If,,@code{.if}}. It marks the beginning of a section
4425 of code to be assembled if the condition for the preceding @code{.if}
4429 @section @code{.elseif}
4431 @cindex @code{elseif} directive
4432 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4433 assembly; see @ref{If,,@code{.if}}. It is shorthand for beginning a new
4434 @code{.if} block that would otherwise fill the entire @code{.else} section.
4437 @section @code{.end}
4439 @cindex @code{end} directive
4440 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4441 process anything in the file past the @code{.end} directive.
4445 @section @code{.endef}
4447 @cindex @code{endef} directive
4448 This directive flags the end of a symbol definition begun with
4452 @samp{.endef} is only meaningful when generating COFF format output; if
4453 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4454 directive but ignores it.
4459 @section @code{.endfunc}
4460 @cindex @code{endfunc} directive
4461 @code{.endfunc} marks the end of a function specified with @code{.func}.
4464 @section @code{.endif}
4466 @cindex @code{endif} directive
4467 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4468 it marks the end of a block of code that is only assembled
4469 conditionally. @xref{If,,@code{.if}}.
4472 @section @code{.equ @var{symbol}, @var{expression}}
4474 @cindex @code{equ} directive
4475 @cindex assigning values to symbols
4476 @cindex symbols, assigning values to
4477 This directive sets the value of @var{symbol} to @var{expression}.
4478 It is synonymous with @samp{.set}; see @ref{Set,,@code{.set}}.
4481 The syntax for @code{equ} on the HPPA is
4482 @samp{@var{symbol} .equ @var{expression}}.
4486 The syntax for @code{equ} on the Z80 is
4487 @samp{@var{symbol} equ @var{expression}}.
4488 On the Z80 it is an eror if @var{symbol} is already defined,
4489 but the symbol is not protected from later redefinition.
4490 Compare @ref{Equiv}.
4494 @section @code{.equiv @var{symbol}, @var{expression}}
4495 @cindex @code{equiv} directive
4496 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4497 the assembler will signal an error if @var{symbol} is already defined. Note a
4498 symbol which has been referenced but not actually defined is considered to be
4501 Except for the contents of the error message, this is roughly equivalent to
4508 plus it protects the symbol from later redefinition.
4511 @section @code{.eqv @var{symbol}, @var{expression}}
4512 @cindex @code{eqv} directive
4513 The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to
4514 evaluate the expression or any part of it immediately. Instead each time
4515 the resulting symbol is used in an expression, a snapshot of its current
4519 @section @code{.err}
4520 @cindex @code{err} directive
4521 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4522 message and, unless the @option{-Z} option was used, it will not generate an
4523 object file. This can be used to signal an error in conditionally compiled code.
4526 @section @code{.error "@var{string}"}
4527 @cindex error directive
4529 Similarly to @code{.err}, this directive emits an error, but you can specify a
4530 string that will be emitted as the error message. If you don't specify the
4531 message, it defaults to @code{".error directive invoked in source file"}.
4532 @xref{Errors, ,Error and Warning Messages}.
4535 .error "This code has not been assembled and tested."
4539 @section @code{.exitm}
4540 Exit early from the current macro definition. @xref{Macro}.
4543 @section @code{.extern}
4545 @cindex @code{extern} directive
4546 @code{.extern} is accepted in the source program---for compatibility
4547 with other assemblers---but it is ignored. @command{@value{AS}} treats
4548 all undefined symbols as external.
4551 @section @code{.fail @var{expression}}
4553 @cindex @code{fail} directive
4554 Generates an error or a warning. If the value of the @var{expression} is 500
4555 or more, @command{@value{AS}} will print a warning message. If the value is less
4556 than 500, @command{@value{AS}} will print an error message. The message will
4557 include the value of @var{expression}. This can occasionally be useful inside
4558 complex nested macros or conditional assembly.
4561 @section @code{.file}
4562 @cindex @code{file} directive
4564 @ifclear no-file-dir
4565 There are two different versions of the @code{.file} directive. Targets
4566 that support DWARF2 line number information use the DWARF2 version of
4567 @code{.file}. Other targets use the default version.
4569 @subheading Default Version
4571 @cindex logical file name
4572 @cindex file name, logical
4573 This version of the @code{.file} directive tells @command{@value{AS}} that we
4574 are about to start a new logical file. The syntax is:
4580 @var{string} is the new file name. In general, the filename is
4581 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4582 to specify an empty file name, you must give the quotes--@code{""}. This
4583 statement may go away in future: it is only recognized to be compatible with
4584 old @command{@value{AS}} programs.
4586 @subheading DWARF2 Version
4589 When emitting DWARF2 line number information, @code{.file} assigns filenames
4590 to the @code{.debug_line} file name table. The syntax is:
4593 .file @var{fileno} @var{filename}
4596 The @var{fileno} operand should be a unique positive integer to use as the
4597 index of the entry in the table. The @var{filename} operand is a C string
4600 The detail of filename indices is exposed to the user because the filename
4601 table is shared with the @code{.debug_info} section of the DWARF2 debugging
4602 information, and thus the user must know the exact indices that table
4606 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4608 @cindex @code{fill} directive
4609 @cindex writing patterns in memory
4610 @cindex patterns, writing in memory
4611 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4612 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4613 may be zero or more. @var{Size} may be zero or more, but if it is
4614 more than 8, then it is deemed to have the value 8, compatible with
4615 other people's assemblers. The contents of each @var{repeat} bytes
4616 is taken from an 8-byte number. The highest order 4 bytes are
4617 zero. The lowest order 4 bytes are @var{value} rendered in the
4618 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4619 Each @var{size} bytes in a repetition is taken from the lowest order
4620 @var{size} bytes of this number. Again, this bizarre behavior is
4621 compatible with other people's assemblers.
4623 @var{size} and @var{value} are optional.
4624 If the second comma and @var{value} are absent, @var{value} is
4625 assumed zero. If the first comma and following tokens are absent,
4626 @var{size} is assumed to be 1.
4629 @section @code{.float @var{flonums}}
4631 @cindex floating point numbers (single)
4632 @cindex @code{float} directive
4633 This directive assembles zero or more flonums, separated by commas. It
4634 has the same effect as @code{.single}.
4636 The exact kind of floating point numbers emitted depends on how
4637 @command{@value{AS}} is configured.
4638 @xref{Machine Dependencies}.
4642 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4643 in @sc{ieee} format.
4648 @section @code{.func @var{name}[,@var{label}]}
4649 @cindex @code{func} directive
4650 @code{.func} emits debugging information to denote function @var{name}, and
4651 is ignored unless the file is assembled with debugging enabled.
4652 Only @samp{--gstabs[+]} is currently supported.
4653 @var{label} is the entry point of the function and if omitted @var{name}
4654 prepended with the @samp{leading char} is used.
4655 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4656 All functions are currently defined to have @code{void} return type.
4657 The function must be terminated with @code{.endfunc}.
4660 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4662 @cindex @code{global} directive
4663 @cindex symbol, making visible to linker
4664 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4665 @var{symbol} in your partial program, its value is made available to
4666 other partial programs that are linked with it. Otherwise,
4667 @var{symbol} takes its attributes from a symbol of the same name
4668 from another file linked into the same program.
4670 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4671 compatibility with other assemblers.
4674 On the HPPA, @code{.global} is not always enough to make it accessible to other
4675 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4676 @xref{HPPA Directives, ,HPPA Assembler Directives}.
4681 @section @code{.gnu_attribute @var{tag},@var{value}}
4682 Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
4685 @section @code{.hidden @var{names}}
4687 @cindex @code{hidden} directive
4689 This is one of the ELF visibility directives. The other two are
4690 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4691 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4693 This directive overrides the named symbols default visibility (which is set by
4694 their binding: local, global or weak). The directive sets the visibility to
4695 @code{hidden} which means that the symbols are not visible to other components.
4696 Such symbols are always considered to be @code{protected} as well.
4700 @section @code{.hword @var{expressions}}
4702 @cindex @code{hword} directive
4703 @cindex integers, 16-bit
4704 @cindex numbers, 16-bit
4705 @cindex sixteen bit integers
4706 This expects zero or more @var{expressions}, and emits
4707 a 16 bit number for each.
4710 This directive is a synonym for @samp{.short}; depending on the target
4711 architecture, it may also be a synonym for @samp{.word}.
4715 This directive is a synonym for @samp{.short}.
4718 This directive is a synonym for both @samp{.short} and @samp{.word}.
4723 @section @code{.ident}
4725 @cindex @code{ident} directive
4727 This directive is used by some assemblers to place tags in object files. The
4728 behavior of this directive varies depending on the target. When using the
4729 a.out object file format, @command{@value{AS}} simply accepts the directive for
4730 source-file compatibility with existing assemblers, but does not emit anything
4731 for it. When using COFF, comments are emitted to the @code{.comment} or
4732 @code{.rdata} section, depending on the target. When using ELF, comments are
4733 emitted to the @code{.comment} section.
4736 @section @code{.if @var{absolute expression}}
4738 @cindex conditional assembly
4739 @cindex @code{if} directive
4740 @code{.if} marks the beginning of a section of code which is only
4741 considered part of the source program being assembled if the argument
4742 (which must be an @var{absolute expression}) is non-zero. The end of
4743 the conditional section of code must be marked by @code{.endif}
4744 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4745 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4746 If you have several conditions to check, @code{.elseif} may be used to avoid
4747 nesting blocks if/else within each subsequent @code{.else} block.
4749 The following variants of @code{.if} are also supported:
4751 @cindex @code{ifdef} directive
4752 @item .ifdef @var{symbol}
4753 Assembles the following section of code if the specified @var{symbol}
4754 has been defined. Note a symbol which has been referenced but not yet defined
4755 is considered to be undefined.
4757 @cindex @code{ifb} directive
4758 @item .ifb @var{text}
4759 Assembles the following section of code if the operand is blank (empty).
4761 @cindex @code{ifc} directive
4762 @item .ifc @var{string1},@var{string2}
4763 Assembles the following section of code if the two strings are the same. The
4764 strings may be optionally quoted with single quotes. If they are not quoted,
4765 the first string stops at the first comma, and the second string stops at the
4766 end of the line. Strings which contain whitespace should be quoted. The
4767 string comparison is case sensitive.
4769 @cindex @code{ifeq} directive
4770 @item .ifeq @var{absolute expression}
4771 Assembles the following section of code if the argument is zero.
4773 @cindex @code{ifeqs} directive
4774 @item .ifeqs @var{string1},@var{string2}
4775 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4777 @cindex @code{ifge} directive
4778 @item .ifge @var{absolute expression}
4779 Assembles the following section of code if the argument is greater than or
4782 @cindex @code{ifgt} directive
4783 @item .ifgt @var{absolute expression}
4784 Assembles the following section of code if the argument is greater than zero.
4786 @cindex @code{ifle} directive
4787 @item .ifle @var{absolute expression}
4788 Assembles the following section of code if the argument is less than or equal
4791 @cindex @code{iflt} directive
4792 @item .iflt @var{absolute expression}
4793 Assembles the following section of code if the argument is less than zero.
4795 @cindex @code{ifnb} directive
4796 @item .ifnb @var{text}
4797 Like @code{.ifb}, but the sense of the test is reversed: this assembles the
4798 following section of code if the operand is non-blank (non-empty).
4800 @cindex @code{ifnc} directive
4801 @item .ifnc @var{string1},@var{string2}.
4802 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4803 following section of code if the two strings are not the same.
4805 @cindex @code{ifndef} directive
4806 @cindex @code{ifnotdef} directive
4807 @item .ifndef @var{symbol}
4808 @itemx .ifnotdef @var{symbol}
4809 Assembles the following section of code if the specified @var{symbol}
4810 has not been defined. Both spelling variants are equivalent. Note a symbol
4811 which has been referenced but not yet defined is considered to be undefined.
4813 @cindex @code{ifne} directive
4814 @item .ifne @var{absolute expression}
4815 Assembles the following section of code if the argument is not equal to zero
4816 (in other words, this is equivalent to @code{.if}).
4818 @cindex @code{ifnes} directive
4819 @item .ifnes @var{string1},@var{string2}
4820 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4821 following section of code if the two strings are not the same.
4825 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4827 @cindex @code{incbin} directive
4828 @cindex binary files, including
4829 The @code{incbin} directive includes @var{file} verbatim at the current
4830 location. You can control the search paths used with the @samp{-I} command-line
4831 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4834 The @var{skip} argument skips a number of bytes from the start of the
4835 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4836 read. Note that the data is not aligned in any way, so it is the user's
4837 responsibility to make sure that proper alignment is provided both before and
4838 after the @code{incbin} directive.
4841 @section @code{.include "@var{file}"}
4843 @cindex @code{include} directive
4844 @cindex supporting files, including
4845 @cindex files, including
4846 This directive provides a way to include supporting files at specified
4847 points in your source program. The code from @var{file} is assembled as
4848 if it followed the point of the @code{.include}; when the end of the
4849 included file is reached, assembly of the original file continues. You
4850 can control the search paths used with the @samp{-I} command-line option
4851 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4855 @section @code{.int @var{expressions}}
4857 @cindex @code{int} directive
4858 @cindex integers, 32-bit
4859 Expect zero or more @var{expressions}, of any section, separated by commas.
4860 For each expression, emit a number that, at run time, is the value of that
4861 expression. The byte order and bit size of the number depends on what kind
4862 of target the assembly is for.
4866 On most forms of the H8/300, @code{.int} emits 16-bit
4867 integers. On the H8/300H and the Renesas SH, however, @code{.int} emits
4874 @section @code{.internal @var{names}}
4876 @cindex @code{internal} directive
4878 This is one of the ELF visibility directives. The other two are
4879 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4880 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4882 This directive overrides the named symbols default visibility (which is set by
4883 their binding: local, global or weak). The directive sets the visibility to
4884 @code{internal} which means that the symbols are considered to be @code{hidden}
4885 (i.e., not visible to other components), and that some extra, processor specific
4886 processing must also be performed upon the symbols as well.
4890 @section @code{.irp @var{symbol},@var{values}}@dots{}
4892 @cindex @code{irp} directive
4893 Evaluate a sequence of statements assigning different values to @var{symbol}.
4894 The sequence of statements starts at the @code{.irp} directive, and is
4895 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4896 set to @var{value}, and the sequence of statements is assembled. If no
4897 @var{value} is listed, the sequence of statements is assembled once, with
4898 @var{symbol} set to the null string. To refer to @var{symbol} within the
4899 sequence of statements, use @var{\symbol}.
4901 For example, assembling
4909 is equivalent to assembling
4917 For some caveats with the spelling of @var{symbol}, see also @ref{Macro}.
4920 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4922 @cindex @code{irpc} directive
4923 Evaluate a sequence of statements assigning different values to @var{symbol}.
4924 The sequence of statements starts at the @code{.irpc} directive, and is
4925 terminated by an @code{.endr} directive. For each character in @var{value},
4926 @var{symbol} is set to the character, and the sequence of statements is
4927 assembled. If no @var{value} is listed, the sequence of statements is
4928 assembled once, with @var{symbol} set to the null string. To refer to
4929 @var{symbol} within the sequence of statements, use @var{\symbol}.
4931 For example, assembling
4939 is equivalent to assembling
4947 For some caveats with the spelling of @var{symbol}, see also the discussion
4951 @section @code{.lcomm @var{symbol} , @var{length}}
4953 @cindex @code{lcomm} directive
4954 @cindex local common symbols
4955 @cindex symbols, local common
4956 Reserve @var{length} (an absolute expression) bytes for a local common
4957 denoted by @var{symbol}. The section and value of @var{symbol} are
4958 those of the new local common. The addresses are allocated in the bss
4959 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4960 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4961 not visible to @code{@value{LD}}.
4964 Some targets permit a third argument to be used with @code{.lcomm}. This
4965 argument specifies the desired alignment of the symbol in the bss section.
4969 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4970 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4974 @section @code{.lflags}
4976 @cindex @code{lflags} directive (ignored)
4977 @command{@value{AS}} accepts this directive, for compatibility with other
4978 assemblers, but ignores it.
4980 @ifclear no-line-dir
4982 @section @code{.line @var{line-number}}
4984 @cindex @code{line} directive
4985 @cindex logical line number
4987 Change the logical line number. @var{line-number} must be an absolute
4988 expression. The next line has that logical line number. Therefore any other
4989 statements on the current line (after a statement separator character) are
4990 reported as on logical line number @var{line-number} @minus{} 1. One day
4991 @command{@value{AS}} will no longer support this directive: it is recognized only
4992 for compatibility with existing assembler programs.
4995 Even though this is a directive associated with the @code{a.out} or
4996 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4997 when producing COFF output, and treats @samp{.line} as though it
4998 were the COFF @samp{.ln} @emph{if} it is found outside a
4999 @code{.def}/@code{.endef} pair.
5001 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
5002 used by compilers to generate auxiliary symbol information for
5007 @section @code{.linkonce [@var{type}]}
5009 @cindex @code{linkonce} directive
5010 @cindex common sections
5011 Mark the current section so that the linker only includes a single copy of it.
5012 This may be used to include the same section in several different object files,
5013 but ensure that the linker will only include it once in the final output file.
5014 The @code{.linkonce} pseudo-op must be used for each instance of the section.
5015 Duplicate sections are detected based on the section name, so it should be
5018 This directive is only supported by a few object file formats; as of this
5019 writing, the only object file format which supports it is the Portable
5020 Executable format used on Windows NT.
5022 The @var{type} argument is optional. If specified, it must be one of the
5023 following strings. For example:
5027 Not all types may be supported on all object file formats.
5031 Silently discard duplicate sections. This is the default.
5034 Warn if there are duplicate sections, but still keep only one copy.
5037 Warn if any of the duplicates have different sizes.
5040 Warn if any of the duplicates do not have exactly the same contents.
5044 @section @code{.list}
5046 @cindex @code{list} directive
5047 @cindex listing control, turning on
5048 Control (in conjunction with the @code{.nolist} directive) whether or
5049 not assembly listings are generated. These two directives maintain an
5050 internal counter (which is zero initially). @code{.list} increments the
5051 counter, and @code{.nolist} decrements it. Assembly listings are
5052 generated whenever the counter is greater than zero.
5054 By default, listings are disabled. When you enable them (with the
5055 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
5056 the initial value of the listing counter is one.
5059 @section @code{.ln @var{line-number}}
5061 @cindex @code{ln} directive
5062 @ifclear no-line-dir
5063 @samp{.ln} is a synonym for @samp{.line}.
5066 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
5067 must be an absolute expression. The next line has that logical
5068 line number, so any other statements on the current line (after a
5069 statement separator character @code{;}) are reported as on logical
5070 line number @var{line-number} @minus{} 1.
5073 This directive is accepted, but ignored, when @command{@value{AS}} is
5074 configured for @code{b.out}; its effect is only associated with COFF
5080 @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]}
5081 @cindex @code{loc} directive
5082 When emitting DWARF2 line number information,
5083 the @code{.loc} directive will add a row to the @code{.debug_line} line
5084 number matrix corresponding to the immediately following assembly
5085 instruction. The @var{fileno}, @var{lineno}, and optional @var{column}
5086 arguments will be applied to the @code{.debug_line} state machine before
5089 The @var{options} are a sequence of the following tokens in any order:
5093 This option will set the @code{basic_block} register in the
5094 @code{.debug_line} state machine to @code{true}.
5097 This option will set the @code{prologue_end} register in the
5098 @code{.debug_line} state machine to @code{true}.
5100 @item epilogue_begin
5101 This option will set the @code{epilogue_begin} register in the
5102 @code{.debug_line} state machine to @code{true}.
5104 @item is_stmt @var{value}
5105 This option will set the @code{is_stmt} register in the
5106 @code{.debug_line} state machine to @code{value}, which must be
5109 @item isa @var{value}
5110 This directive will set the @code{isa} register in the @code{.debug_line}
5111 state machine to @var{value}, which must be an unsigned integer.
5115 @node Loc_mark_labels
5116 @section @code{.loc_mark_labels @var{enable}}
5117 @cindex @code{loc_mark_labels} directive
5118 When emitting DWARF2 line number information,
5119 the @code{.loc_mark_labels} directive makes the assembler emit an entry
5120 to the @code{.debug_line} line number matrix with the @code{basic_block}
5121 register in the state machine set whenever a code label is seen.
5122 The @var{enable} argument should be either 1 or 0, to enable or disable
5123 this function respectively.
5127 @section @code{.local @var{names}}
5129 @cindex @code{local} directive
5130 This directive, which is available for ELF targets, marks each symbol in
5131 the comma-separated list of @code{names} as a local symbol so that it
5132 will not be externally visible. If the symbols do not already exist,
5133 they will be created.
5135 For targets where the @code{.lcomm} directive (@pxref{Lcomm}) does not
5136 accept an alignment argument, which is the case for most ELF targets,
5137 the @code{.local} directive can be used in combination with @code{.comm}
5138 (@pxref{Comm}) to define aligned local common data.
5142 @section @code{.long @var{expressions}}
5144 @cindex @code{long} directive
5145 @code{.long} is the same as @samp{.int}. @xref{Int,,@code{.int}}.
5148 @c no one seems to know what this is for or whether this description is
5149 @c what it really ought to do
5151 @section @code{.lsym @var{symbol}, @var{expression}}
5153 @cindex @code{lsym} directive
5154 @cindex symbol, not referenced in assembly
5155 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
5156 the hash table, ensuring it cannot be referenced by name during the
5157 rest of the assembly. This sets the attributes of the symbol to be
5158 the same as the expression value:
5160 @var{other} = @var{descriptor} = 0
5161 @var{type} = @r{(section of @var{expression})}
5162 @var{value} = @var{expression}
5165 The new symbol is not flagged as external.
5169 @section @code{.macro}
5172 The commands @code{.macro} and @code{.endm} allow you to define macros that
5173 generate assembly output. For example, this definition specifies a macro
5174 @code{sum} that puts a sequence of numbers into memory:
5177 .macro sum from=0, to=5
5186 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
5198 @item .macro @var{macname}
5199 @itemx .macro @var{macname} @var{macargs} @dots{}
5200 @cindex @code{macro} directive
5201 Begin the definition of a macro called @var{macname}. If your macro
5202 definition requires arguments, specify their names after the macro name,
5203 separated by commas or spaces. You can qualify the macro argument to
5204 indicate whether all invocations must specify a non-blank value (through
5205 @samp{:@code{req}}), or whether it takes all of the remaining arguments
5206 (through @samp{:@code{vararg}}). You can supply a default value for any
5207 macro argument by following the name with @samp{=@var{deflt}}. You
5208 cannot define two macros with the same @var{macname} unless it has been
5209 subject to the @code{.purgem} directive (@pxref{Purgem}) between the two
5210 definitions. For example, these are all valid @code{.macro} statements:
5214 Begin the definition of a macro called @code{comm}, which takes no
5217 @item .macro plus1 p, p1
5218 @itemx .macro plus1 p p1
5219 Either statement begins the definition of a macro called @code{plus1},
5220 which takes two arguments; within the macro definition, write
5221 @samp{\p} or @samp{\p1} to evaluate the arguments.
5223 @item .macro reserve_str p1=0 p2
5224 Begin the definition of a macro called @code{reserve_str}, with two
5225 arguments. The first argument has a default value, but not the second.
5226 After the definition is complete, you can call the macro either as
5227 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
5228 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
5229 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
5230 @samp{0}, and @samp{\p2} evaluating to @var{b}).
5232 @item .macro m p1:req, p2=0, p3:vararg
5233 Begin the definition of a macro called @code{m}, with at least three
5234 arguments. The first argument must always have a value specified, but
5235 not the second, which instead has a default value. The third formal
5236 will get assigned all remaining arguments specified at invocation time.
5238 When you call a macro, you can specify the argument values either by
5239 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
5240 @samp{sum to=17, from=9}.
5244 Note that since each of the @var{macargs} can be an identifier exactly
5245 as any other one permitted by the target architecture, there may be
5246 occasional problems if the target hand-crafts special meanings to certain
5247 characters when they occur in a special position. For example, if the colon
5248 (@code{:}) is generally permitted to be part of a symbol name, but the
5249 architecture specific code special-cases it when occurring as the final
5250 character of a symbol (to denote a label), then the macro parameter
5251 replacement code will have no way of knowing that and consider the whole
5252 construct (including the colon) an identifier, and check only this
5253 identifier for being the subject to parameter substitution. So for example
5254 this macro definition:
5262 might not work as expected. Invoking @samp{label foo} might not create a label
5263 called @samp{foo} but instead just insert the text @samp{\l:} into the
5264 assembler source, probably generating an error about an unrecognised
5267 Similarly problems might occur with the period character (@samp{.})
5268 which is often allowed inside opcode names (and hence identifier names). So
5269 for example constructing a macro to build an opcode from a base name and a
5270 length specifier like this:
5273 .macro opcode base length
5278 and invoking it as @samp{opcode store l} will not create a @samp{store.l}
5279 instruction but instead generate some kind of error as the assembler tries to
5280 interpret the text @samp{\base.\length}.
5282 There are several possible ways around this problem:
5285 @item Insert white space
5286 If it is possible to use white space characters then this is the simplest
5295 @item Use @samp{\()}
5296 The string @samp{\()} can be used to separate the end of a macro argument from
5297 the following text. eg:
5300 .macro opcode base length
5305 @item Use the alternate macro syntax mode
5306 In the alternative macro syntax mode the ampersand character (@samp{&}) can be
5307 used as a separator. eg:
5317 Note: this problem of correctly identifying string parameters to pseudo ops
5318 also applies to the identifiers used in @code{.irp} (@pxref{Irp})
5319 and @code{.irpc} (@pxref{Irpc}) as well.
5322 @cindex @code{endm} directive
5323 Mark the end of a macro definition.
5326 @cindex @code{exitm} directive
5327 Exit early from the current macro definition.
5329 @cindex number of macros executed
5330 @cindex macros, count executed
5332 @command{@value{AS}} maintains a counter of how many macros it has
5333 executed in this pseudo-variable; you can copy that number to your
5334 output with @samp{\@@}, but @emph{only within a macro definition}.
5336 @item LOCAL @var{name} [ , @dots{} ]
5337 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
5338 macro syntax'' with @samp{--alternate} or @code{.altmacro}.}
5339 @xref{Altmacro,,@code{.altmacro}}.
5343 @section @code{.mri @var{val}}
5345 @cindex @code{mri} directive
5346 @cindex MRI mode, temporarily
5347 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
5348 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
5349 affects code assembled until the next @code{.mri} directive, or until the end
5350 of the file. @xref{M, MRI mode, MRI mode}.
5353 @section @code{.noaltmacro}
5354 Disable alternate macro mode. @xref{Altmacro}.
5357 @section @code{.nolist}
5359 @cindex @code{nolist} directive
5360 @cindex listing control, turning off
5361 Control (in conjunction with the @code{.list} directive) whether or
5362 not assembly listings are generated. These two directives maintain an
5363 internal counter (which is zero initially). @code{.list} increments the
5364 counter, and @code{.nolist} decrements it. Assembly listings are
5365 generated whenever the counter is greater than zero.
5368 @section @code{.octa @var{bignums}}
5370 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
5371 @cindex @code{octa} directive
5372 @cindex integer, 16-byte
5373 @cindex sixteen byte integer
5374 This directive expects zero or more bignums, separated by commas. For each
5375 bignum, it emits a 16-byte integer.
5377 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
5378 hence @emph{octa}-word for 16 bytes.
5381 @section @code{.org @var{new-lc} , @var{fill}}
5383 @cindex @code{org} directive
5384 @cindex location counter, advancing
5385 @cindex advancing location counter
5386 @cindex current address, advancing
5387 Advance the location counter of the current section to
5388 @var{new-lc}. @var{new-lc} is either an absolute expression or an
5389 expression with the same section as the current subsection. That is,
5390 you can't use @code{.org} to cross sections: if @var{new-lc} has the
5391 wrong section, the @code{.org} directive is ignored. To be compatible
5392 with former assemblers, if the section of @var{new-lc} is absolute,
5393 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
5394 is the same as the current subsection.
5396 @code{.org} may only increase the location counter, or leave it
5397 unchanged; you cannot use @code{.org} to move the location counter
5400 @c double negative used below "not undefined" because this is a specific
5401 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
5402 @c section. doc@cygnus.com 18feb91
5403 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
5404 may not be undefined. If you really detest this restriction we eagerly await
5405 a chance to share your improved assembler.
5407 Beware that the origin is relative to the start of the section, not
5408 to the start of the subsection. This is compatible with other
5409 people's assemblers.
5411 When the location counter (of the current subsection) is advanced, the
5412 intervening bytes are filled with @var{fill} which should be an
5413 absolute expression. If the comma and @var{fill} are omitted,
5414 @var{fill} defaults to zero.
5417 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
5419 @cindex padding the location counter given a power of two
5420 @cindex @code{p2align} directive
5421 Pad the location counter (in the current subsection) to a particular
5422 storage boundary. The first expression (which must be absolute) is the
5423 number of low-order zero bits the location counter must have after
5424 advancement. For example @samp{.p2align 3} advances the location
5425 counter until it a multiple of 8. If the location counter is already a
5426 multiple of 8, no change is needed.
5428 The second expression (also absolute) gives the fill value to be stored in the
5429 padding bytes. It (and the comma) may be omitted. If it is omitted, the
5430 padding bytes are normally zero. However, on some systems, if the section is
5431 marked as containing code and the fill value is omitted, the space is filled
5432 with no-op instructions.
5434 The third expression is also absolute, and is also optional. If it is present,
5435 it is the maximum number of bytes that should be skipped by this alignment
5436 directive. If doing the alignment would require skipping more bytes than the
5437 specified maximum, then the alignment is not done at all. You can omit the
5438 fill value (the second argument) entirely by simply using two commas after the
5439 required alignment; this can be useful if you want the alignment to be filled
5440 with no-op instructions when appropriate.
5442 @cindex @code{p2alignw} directive
5443 @cindex @code{p2alignl} directive
5444 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
5445 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
5446 pattern as a two byte word value. The @code{.p2alignl} directives treats the
5447 fill pattern as a four byte longword value. For example, @code{.p2alignw
5448 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
5449 filled in with the value 0x368d (the exact placement of the bytes depends upon
5450 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
5455 @section @code{.popsection}
5457 @cindex @code{popsection} directive
5458 @cindex Section Stack
5459 This is one of the ELF section stack manipulation directives. The others are
5460 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5461 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
5464 This directive replaces the current section (and subsection) with the top
5465 section (and subsection) on the section stack. This section is popped off the
5471 @section @code{.previous}
5473 @cindex @code{previous} directive
5474 @cindex Section Stack
5475 This is one of the ELF section stack manipulation directives. The others are
5476 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5477 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
5478 (@pxref{PopSection}).
5480 This directive swaps the current section (and subsection) with most recently
5481 referenced section/subsection pair prior to this one. Multiple
5482 @code{.previous} directives in a row will flip between two sections (and their
5483 subsections). For example:
5495 Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
5501 # Now in section A subsection 1
5505 # Now in section B subsection 0
5508 # Now in section B subsection 1
5511 # Now in section B subsection 0
5515 Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
5516 section B and 0x9abc into subsection 1 of section B.
5518 In terms of the section stack, this directive swaps the current section with
5519 the top section on the section stack.
5523 @section @code{.print @var{string}}
5525 @cindex @code{print} directive
5526 @command{@value{AS}} will print @var{string} on the standard output during
5527 assembly. You must put @var{string} in double quotes.
5531 @section @code{.protected @var{names}}
5533 @cindex @code{protected} directive
5535 This is one of the ELF visibility directives. The other two are
5536 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
5538 This directive overrides the named symbols default visibility (which is set by
5539 their binding: local, global or weak). The directive sets the visibility to
5540 @code{protected} which means that any references to the symbols from within the
5541 components that defines them must be resolved to the definition in that
5542 component, even if a definition in another component would normally preempt
5547 @section @code{.psize @var{lines} , @var{columns}}
5549 @cindex @code{psize} directive
5550 @cindex listing control: paper size
5551 @cindex paper size, for listings
5552 Use this directive to declare the number of lines---and, optionally, the
5553 number of columns---to use for each page, when generating listings.
5555 If you do not use @code{.psize}, listings use a default line-count
5556 of 60. You may omit the comma and @var{columns} specification; the
5557 default width is 200 columns.
5559 @command{@value{AS}} generates formfeeds whenever the specified number of
5560 lines is exceeded (or whenever you explicitly request one, using
5563 If you specify @var{lines} as @code{0}, no formfeeds are generated save
5564 those explicitly specified with @code{.eject}.
5567 @section @code{.purgem @var{name}}
5569 @cindex @code{purgem} directive
5570 Undefine the macro @var{name}, so that later uses of the string will not be
5571 expanded. @xref{Macro}.
5575 @section @code{.pushsection @var{name} [, @var{subsection}] [, "@var{flags}"[, @@@var{type}[,@var{arguments}]]]}
5577 @cindex @code{pushsection} directive
5578 @cindex Section Stack
5579 This is one of the ELF section stack manipulation directives. The others are
5580 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
5581 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5584 This directive pushes the current section (and subsection) onto the
5585 top of the section stack, and then replaces the current section and
5586 subsection with @code{name} and @code{subsection}. The optional
5587 @code{flags}, @code{type} and @code{arguments} are treated the same
5588 as in the @code{.section} (@pxref{Section}) directive.
5592 @section @code{.quad @var{bignums}}
5594 @cindex @code{quad} directive
5595 @code{.quad} expects zero or more bignums, separated by commas. For
5596 each bignum, it emits
5598 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
5599 warning message; and just takes the lowest order 8 bytes of the bignum.
5600 @cindex eight-byte integer
5601 @cindex integer, 8-byte
5603 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
5604 hence @emph{quad}-word for 8 bytes.
5607 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
5608 warning message; and just takes the lowest order 16 bytes of the bignum.
5609 @cindex sixteen-byte integer
5610 @cindex integer, 16-byte
5614 @section @code{.reloc @var{offset}, @var{reloc_name}[, @var{expression}]}
5616 @cindex @code{reloc} directive
5617 Generate a relocation at @var{offset} of type @var{reloc_name} with value
5618 @var{expression}. If @var{offset} is a number, the relocation is generated in
5619 the current section. If @var{offset} is an expression that resolves to a
5620 symbol plus offset, the relocation is generated in the given symbol's section.
5621 @var{expression}, if present, must resolve to a symbol plus addend or to an
5622 absolute value, but note that not all targets support an addend. e.g. ELF REL
5623 targets such as i386 store an addend in the section contents rather than in the
5624 relocation. This low level interface does not support addends stored in the
5628 @section @code{.rept @var{count}}
5630 @cindex @code{rept} directive
5631 Repeat the sequence of lines between the @code{.rept} directive and the next
5632 @code{.endr} directive @var{count} times.
5634 For example, assembling
5642 is equivalent to assembling
5651 @section @code{.sbttl "@var{subheading}"}
5653 @cindex @code{sbttl} directive
5654 @cindex subtitles for listings
5655 @cindex listing control: subtitle
5656 Use @var{subheading} as the title (third line, immediately after the
5657 title line) when generating assembly listings.
5659 This directive affects subsequent pages, as well as the current page if
5660 it appears within ten lines of the top of a page.
5664 @section @code{.scl @var{class}}
5666 @cindex @code{scl} directive
5667 @cindex symbol storage class (COFF)
5668 @cindex COFF symbol storage class
5669 Set the storage-class value for a symbol. This directive may only be
5670 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
5671 whether a symbol is static or external, or it may record further
5672 symbolic debugging information.
5675 The @samp{.scl} directive is primarily associated with COFF output; when
5676 configured to generate @code{b.out} output format, @command{@value{AS}}
5677 accepts this directive but ignores it.
5683 @section @code{.section @var{name}}
5685 @cindex named section
5686 Use the @code{.section} directive to assemble the following code into a section
5689 This directive is only supported for targets that actually support arbitrarily
5690 named sections; on @code{a.out} targets, for example, it is not accepted, even
5691 with a standard @code{a.out} section name.
5695 @c only print the extra heading if both COFF and ELF are set
5696 @subheading COFF Version
5699 @cindex @code{section} directive (COFF version)
5700 For COFF targets, the @code{.section} directive is used in one of the following
5704 .section @var{name}[, "@var{flags}"]
5705 .section @var{name}[, @var{subsection}]
5708 If the optional argument is quoted, it is taken as flags to use for the
5709 section. Each flag is a single character. The following flags are recognized:
5712 bss section (uninitialized data)
5714 section is not loaded
5724 shared section (meaningful for PE targets)
5726 ignored. (For compatibility with the ELF version)
5729 If no flags are specified, the default flags depend upon the section name. If
5730 the section name is not recognized, the default will be for the section to be
5731 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
5732 from the section, rather than adding them, so if they are used on their own it
5733 will be as if no flags had been specified at all.
5735 If the optional argument to the @code{.section} directive is not quoted, it is
5736 taken as a subsection number (@pxref{Sub-Sections}).
5741 @c only print the extra heading if both COFF and ELF are set
5742 @subheading ELF Version
5745 @cindex Section Stack
5746 This is one of the ELF section stack manipulation directives. The others are
5747 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5748 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5749 @code{.previous} (@pxref{Previous}).
5751 @cindex @code{section} directive (ELF version)
5752 For ELF targets, the @code{.section} directive is used like this:
5755 .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]]
5758 The optional @var{flags} argument is a quoted string which may contain any
5759 combination of the following characters:
5762 section is allocatable
5766 section is executable
5768 section is mergeable
5770 section contains zero terminated strings
5772 section is a member of a section group
5774 section is used for thread-local-storage
5777 The optional @var{type} argument may contain one of the following constants:
5780 section contains data
5782 section does not contain data (i.e., section only occupies space)
5784 section contains data which is used by things other than the program
5786 section contains an array of pointers to init functions
5788 section contains an array of pointers to finish functions
5789 @item @@preinit_array
5790 section contains an array of pointers to pre-init functions
5793 Many targets only support the first three section types.
5795 Note on targets where the @code{@@} character is the start of a comment (eg
5796 ARM) then another character is used instead. For example the ARM port uses the
5799 If @var{flags} contains the @code{M} symbol then the @var{type} argument must
5800 be specified as well as an extra argument---@var{entsize}---like this:
5803 .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize}
5806 Sections with the @code{M} flag but not @code{S} flag must contain fixed size
5807 constants, each @var{entsize} octets long. Sections with both @code{M} and
5808 @code{S} must contain zero terminated strings where each character is
5809 @var{entsize} bytes long. The linker may remove duplicates within sections with
5810 the same name, same entity size and same flags. @var{entsize} must be an
5811 absolute expression.
5813 If @var{flags} contains the @code{G} symbol then the @var{type} argument must
5814 be present along with an additional field like this:
5817 .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}]
5820 The @var{GroupName} field specifies the name of the section group to which this
5821 particular section belongs. The optional linkage field can contain:
5824 indicates that only one copy of this section should be retained
5829 Note: if both the @var{M} and @var{G} flags are present then the fields for
5830 the Merge flag should come first, like this:
5833 .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}]
5836 If no flags are specified, the default flags depend upon the section name. If
5837 the section name is not recognized, the default will be for the section to have
5838 none of the above flags: it will not be allocated in memory, nor writable, nor
5839 executable. The section will contain data.
5841 For ELF targets, the assembler supports another type of @code{.section}
5842 directive for compatibility with the Solaris assembler:
5845 .section "@var{name}"[, @var{flags}...]
5848 Note that the section name is quoted. There may be a sequence of comma
5852 section is allocatable
5856 section is executable
5858 section is used for thread local storage
5861 This directive replaces the current section and subsection. See the
5862 contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for
5863 some examples of how this directive and the other section stack directives
5869 @section @code{.set @var{symbol}, @var{expression}}
5871 @cindex @code{set} directive
5872 @cindex symbol value, setting
5873 Set the value of @var{symbol} to @var{expression}. This
5874 changes @var{symbol}'s value and type to conform to
5875 @var{expression}. If @var{symbol} was flagged as external, it remains
5876 flagged (@pxref{Symbol Attributes}).
5878 You may @code{.set} a symbol many times in the same assembly.
5880 If you @code{.set} a global symbol, the value stored in the object
5881 file is the last value stored into it.
5884 The syntax for @code{set} on the HPPA is
5885 @samp{@var{symbol} .set @var{expression}}.
5889 On Z80 @code{set} is a real instruction, use
5890 @samp{@var{symbol} defl @var{expression}} instead.
5894 @section @code{.short @var{expressions}}
5896 @cindex @code{short} directive
5898 @code{.short} is normally the same as @samp{.word}.
5899 @xref{Word,,@code{.word}}.
5901 In some configurations, however, @code{.short} and @code{.word} generate
5902 numbers of different lengths. @xref{Machine Dependencies}.
5906 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5909 This expects zero or more @var{expressions}, and emits
5910 a 16 bit number for each.
5915 @section @code{.single @var{flonums}}
5917 @cindex @code{single} directive
5918 @cindex floating point numbers (single)
5919 This directive assembles zero or more flonums, separated by commas. It
5920 has the same effect as @code{.float}.
5922 The exact kind of floating point numbers emitted depends on how
5923 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5927 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5928 numbers in @sc{ieee} format.
5934 @section @code{.size}
5936 This directive is used to set the size associated with a symbol.
5940 @c only print the extra heading if both COFF and ELF are set
5941 @subheading COFF Version
5944 @cindex @code{size} directive (COFF version)
5945 For COFF targets, the @code{.size} directive is only permitted inside
5946 @code{.def}/@code{.endef} pairs. It is used like this:
5949 .size @var{expression}
5953 @samp{.size} is only meaningful when generating COFF format output; when
5954 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5961 @c only print the extra heading if both COFF and ELF are set
5962 @subheading ELF Version
5965 @cindex @code{size} directive (ELF version)
5966 For ELF targets, the @code{.size} directive is used like this:
5969 .size @var{name} , @var{expression}
5972 This directive sets the size associated with a symbol @var{name}.
5973 The size in bytes is computed from @var{expression} which can make use of label
5974 arithmetic. This directive is typically used to set the size of function
5979 @ifclear no-space-dir
5981 @section @code{.skip @var{size} , @var{fill}}
5983 @cindex @code{skip} directive
5984 @cindex filling memory
5985 This directive emits @var{size} bytes, each of value @var{fill}. Both
5986 @var{size} and @var{fill} are absolute expressions. If the comma and
5987 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5992 @section @code{.sleb128 @var{expressions}}
5994 @cindex @code{sleb128} directive
5995 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5996 compact, variable length representation of numbers used by the DWARF
5997 symbolic debugging format. @xref{Uleb128, ,@code{.uleb128}}.
5999 @ifclear no-space-dir
6001 @section @code{.space @var{size} , @var{fill}}
6003 @cindex @code{space} directive
6004 @cindex filling memory
6005 This directive emits @var{size} bytes, each of value @var{fill}. Both
6006 @var{size} and @var{fill} are absolute expressions. If the comma
6007 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
6012 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
6013 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
6014 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
6015 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
6023 @section @code{.stabd, .stabn, .stabs}
6025 @cindex symbolic debuggers, information for
6026 @cindex @code{stab@var{x}} directives
6027 There are three directives that begin @samp{.stab}.
6028 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
6029 The symbols are not entered in the @command{@value{AS}} hash table: they
6030 cannot be referenced elsewhere in the source file.
6031 Up to five fields are required:
6035 This is the symbol's name. It may contain any character except
6036 @samp{\000}, so is more general than ordinary symbol names. Some
6037 debuggers used to code arbitrarily complex structures into symbol names
6041 An absolute expression. The symbol's type is set to the low 8 bits of
6042 this expression. Any bit pattern is permitted, but @code{@value{LD}}
6043 and debuggers choke on silly bit patterns.
6046 An absolute expression. The symbol's ``other'' attribute is set to the
6047 low 8 bits of this expression.
6050 An absolute expression. The symbol's descriptor is set to the low 16
6051 bits of this expression.
6054 An absolute expression which becomes the symbol's value.
6057 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
6058 or @code{.stabs} statement, the symbol has probably already been created;
6059 you get a half-formed symbol in your object file. This is
6060 compatible with earlier assemblers!
6063 @cindex @code{stabd} directive
6064 @item .stabd @var{type} , @var{other} , @var{desc}
6066 The ``name'' of the symbol generated is not even an empty string.
6067 It is a null pointer, for compatibility. Older assemblers used a
6068 null pointer so they didn't waste space in object files with empty
6071 The symbol's value is set to the location counter,
6072 relocatably. When your program is linked, the value of this symbol
6073 is the address of the location counter when the @code{.stabd} was
6076 @cindex @code{stabn} directive
6077 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
6078 The name of the symbol is set to the empty string @code{""}.
6080 @cindex @code{stabs} directive
6081 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
6082 All five fields are specified.
6088 @section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
6089 "@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
6091 @cindex string, copying to object file
6092 @cindex string8, copying to object file
6093 @cindex string16, copying to object file
6094 @cindex string32, copying to object file
6095 @cindex string64, copying to object file
6096 @cindex @code{string} directive
6097 @cindex @code{string8} directive
6098 @cindex @code{string16} directive
6099 @cindex @code{string32} directive
6100 @cindex @code{string64} directive
6102 Copy the characters in @var{str} to the object file. You may specify more than
6103 one string to copy, separated by commas. Unless otherwise specified for a
6104 particular machine, the assembler marks the end of each string with a 0 byte.
6105 You can use any of the escape sequences described in @ref{Strings,,Strings}.
6107 The variants @code{string16}, @code{string32} and @code{string64} differ from
6108 the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
6109 copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
6110 are stored in target endianness byte order.
6116 .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
6117 .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
6122 @section @code{.struct @var{expression}}
6124 @cindex @code{struct} directive
6125 Switch to the absolute section, and set the section offset to @var{expression},
6126 which must be an absolute expression. You might use this as follows:
6135 This would define the symbol @code{field1} to have the value 0, the symbol
6136 @code{field2} to have the value 4, and the symbol @code{field3} to have the
6137 value 8. Assembly would be left in the absolute section, and you would need to
6138 use a @code{.section} directive of some sort to change to some other section
6139 before further assembly.
6143 @section @code{.subsection @var{name}}
6145 @cindex @code{subsection} directive
6146 @cindex Section Stack
6147 This is one of the ELF section stack manipulation directives. The others are
6148 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
6149 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
6152 This directive replaces the current subsection with @code{name}. The current
6153 section is not changed. The replaced subsection is put onto the section stack
6154 in place of the then current top of stack subsection.
6159 @section @code{.symver}
6160 @cindex @code{symver} directive
6161 @cindex symbol versioning
6162 @cindex versions of symbols
6163 Use the @code{.symver} directive to bind symbols to specific version nodes
6164 within a source file. This is only supported on ELF platforms, and is
6165 typically used when assembling files to be linked into a shared library.
6166 There are cases where it may make sense to use this in objects to be bound
6167 into an application itself so as to override a versioned symbol from a
6170 For ELF targets, the @code{.symver} directive can be used like this:
6172 .symver @var{name}, @var{name2@@nodename}
6174 If the symbol @var{name} is defined within the file
6175 being assembled, the @code{.symver} directive effectively creates a symbol
6176 alias with the name @var{name2@@nodename}, and in fact the main reason that we
6177 just don't try and create a regular alias is that the @var{@@} character isn't
6178 permitted in symbol names. The @var{name2} part of the name is the actual name
6179 of the symbol by which it will be externally referenced. The name @var{name}
6180 itself is merely a name of convenience that is used so that it is possible to
6181 have definitions for multiple versions of a function within a single source
6182 file, and so that the compiler can unambiguously know which version of a
6183 function is being mentioned. The @var{nodename} portion of the alias should be
6184 the name of a node specified in the version script supplied to the linker when
6185 building a shared library. If you are attempting to override a versioned
6186 symbol from a shared library, then @var{nodename} should correspond to the
6187 nodename of the symbol you are trying to override.
6189 If the symbol @var{name} is not defined within the file being assembled, all
6190 references to @var{name} will be changed to @var{name2@@nodename}. If no
6191 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
6194 Another usage of the @code{.symver} directive is:
6196 .symver @var{name}, @var{name2@@@@nodename}
6198 In this case, the symbol @var{name} must exist and be defined within
6199 the file being assembled. It is similar to @var{name2@@nodename}. The
6200 difference is @var{name2@@@@nodename} will also be used to resolve
6201 references to @var{name2} by the linker.
6203 The third usage of the @code{.symver} directive is:
6205 .symver @var{name}, @var{name2@@@@@@nodename}
6207 When @var{name} is not defined within the
6208 file being assembled, it is treated as @var{name2@@nodename}. When
6209 @var{name} is defined within the file being assembled, the symbol
6210 name, @var{name}, will be changed to @var{name2@@@@nodename}.
6215 @section @code{.tag @var{structname}}
6217 @cindex COFF structure debugging
6218 @cindex structure debugging, COFF
6219 @cindex @code{tag} directive
6220 This directive is generated by compilers to include auxiliary debugging
6221 information in the symbol table. It is only permitted inside
6222 @code{.def}/@code{.endef} pairs. Tags are used to link structure
6223 definitions in the symbol table with instances of those structures.
6226 @samp{.tag} is only used when generating COFF format output; when
6227 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
6233 @section @code{.text @var{subsection}}
6235 @cindex @code{text} directive
6236 Tells @command{@value{AS}} to assemble the following statements onto the end of
6237 the text subsection numbered @var{subsection}, which is an absolute
6238 expression. If @var{subsection} is omitted, subsection number zero
6242 @section @code{.title "@var{heading}"}
6244 @cindex @code{title} directive
6245 @cindex listing control: title line
6246 Use @var{heading} as the title (second line, immediately after the
6247 source file name and pagenumber) when generating assembly listings.
6249 This directive affects subsequent pages, as well as the current page if
6250 it appears within ten lines of the top of a page.
6254 @section @code{.type}
6256 This directive is used to set the type of a symbol.
6260 @c only print the extra heading if both COFF and ELF are set
6261 @subheading COFF Version
6264 @cindex COFF symbol type
6265 @cindex symbol type, COFF
6266 @cindex @code{type} directive (COFF version)
6267 For COFF targets, this directive is permitted only within
6268 @code{.def}/@code{.endef} pairs. It is used like this:
6274 This records the integer @var{int} as the type attribute of a symbol table
6278 @samp{.type} is associated only with COFF format output; when
6279 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
6280 directive but ignores it.
6286 @c only print the extra heading if both COFF and ELF are set
6287 @subheading ELF Version
6290 @cindex ELF symbol type
6291 @cindex symbol type, ELF
6292 @cindex @code{type} directive (ELF version)
6293 For ELF targets, the @code{.type} directive is used like this:
6296 .type @var{name} , @var{type description}
6299 This sets the type of symbol @var{name} to be either a
6300 function symbol or an object symbol. There are five different syntaxes
6301 supported for the @var{type description} field, in order to provide
6302 compatibility with various other assemblers.
6304 Because some of the characters used in these syntaxes (such as @samp{@@} and
6305 @samp{#}) are comment characters for some architectures, some of the syntaxes
6306 below do not work on all architectures. The first variant will be accepted by
6307 the GNU assembler on all architectures so that variant should be used for
6308 maximum portability, if you do not need to assemble your code with other
6311 The syntaxes supported are:
6314 .type <name> STT_<TYPE_IN_UPPER_CASE>
6315 .type <name>,#<type>
6316 .type <name>,@@<type>
6317 .type <name>,%<type>
6318 .type <name>,"<type>"
6321 The types supported are:
6326 Mark the symbol as being a function name.
6330 Mark the symbol as being a data object.
6334 Mark the symbol as being a thead-local data object.
6338 Mark the symbol as being a common data object.
6342 Does not mark the symbol in any way. It is supported just for completeness.
6346 Note: Some targets support extra types in addition to those listed above.
6352 @section @code{.uleb128 @var{expressions}}
6354 @cindex @code{uleb128} directive
6355 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
6356 compact, variable length representation of numbers used by the DWARF
6357 symbolic debugging format. @xref{Sleb128, ,@code{.sleb128}}.
6361 @section @code{.val @var{addr}}
6363 @cindex @code{val} directive
6364 @cindex COFF value attribute
6365 @cindex value attribute, COFF
6366 This directive, permitted only within @code{.def}/@code{.endef} pairs,
6367 records the address @var{addr} as the value attribute of a symbol table
6371 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
6372 configured for @code{b.out}, it accepts this directive but ignores it.
6378 @section @code{.version "@var{string}"}
6380 @cindex @code{version} directive
6381 This directive creates a @code{.note} section and places into it an ELF
6382 formatted note of type NT_VERSION. The note's name is set to @code{string}.
6387 @section @code{.vtable_entry @var{table}, @var{offset}}
6389 @cindex @code{vtable_entry} directive
6390 This directive finds or creates a symbol @code{table} and creates a
6391 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
6394 @section @code{.vtable_inherit @var{child}, @var{parent}}
6396 @cindex @code{vtable_inherit} directive
6397 This directive finds the symbol @code{child} and finds or creates the symbol
6398 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
6399 parent whose addend is the value of the child symbol. As a special case the
6400 parent name of @code{0} is treated as referring to the @code{*ABS*} section.
6404 @section @code{.warning "@var{string}"}
6405 @cindex warning directive
6406 Similar to the directive @code{.error}
6407 (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning.
6410 @section @code{.weak @var{names}}
6412 @cindex @code{weak} directive
6413 This directive sets the weak attribute on the comma separated list of symbol
6414 @code{names}. If the symbols do not already exist, they will be created.
6416 On COFF targets other than PE, weak symbols are a GNU extension. This
6417 directive sets the weak attribute on the comma separated list of symbol
6418 @code{names}. If the symbols do not already exist, they will be created.
6420 On the PE target, weak symbols are supported natively as weak aliases.
6421 When a weak symbol is created that is not an alias, GAS creates an
6422 alternate symbol to hold the default value.
6425 @section @code{.weakref @var{alias}, @var{target}}
6427 @cindex @code{weakref} directive
6428 This directive creates an alias to the target symbol that enables the symbol to
6429 be referenced with weak-symbol semantics, but without actually making it weak.
6430 If direct references or definitions of the symbol are present, then the symbol
6431 will not be weak, but if all references to it are through weak references, the
6432 symbol will be marked as weak in the symbol table.
6434 The effect is equivalent to moving all references to the alias to a separate
6435 assembly source file, renaming the alias to the symbol in it, declaring the
6436 symbol as weak there, and running a reloadable link to merge the object files
6437 resulting from the assembly of the new source file and the old source file that
6438 had the references to the alias removed.
6440 The alias itself never makes to the symbol table, and is entirely handled
6441 within the assembler.
6444 @section @code{.word @var{expressions}}
6446 @cindex @code{word} directive
6447 This directive expects zero or more @var{expressions}, of any section,
6448 separated by commas.
6451 For each expression, @command{@value{AS}} emits a 32-bit number.
6454 For each expression, @command{@value{AS}} emits a 16-bit number.
6459 The size of the number emitted, and its byte order,
6460 depend on what target computer the assembly is for.
6463 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
6464 @c happen---32-bit addressability, period; no long/short jumps.
6465 @ifset DIFF-TBL-KLUGE
6466 @cindex difference tables altered
6467 @cindex altered difference tables
6469 @emph{Warning: Special Treatment to support Compilers}
6473 Machines with a 32-bit address space, but that do less than 32-bit
6474 addressing, require the following special treatment. If the machine of
6475 interest to you does 32-bit addressing (or doesn't require it;
6476 @pxref{Machine Dependencies}), you can ignore this issue.
6479 In order to assemble compiler output into something that works,
6480 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
6481 Directives of the form @samp{.word sym1-sym2} are often emitted by
6482 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
6483 directive of the form @samp{.word sym1-sym2}, and the difference between
6484 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
6485 creates a @dfn{secondary jump table}, immediately before the next label.
6486 This secondary jump table is preceded by a short-jump to the
6487 first byte after the secondary table. This short-jump prevents the flow
6488 of control from accidentally falling into the new table. Inside the
6489 table is a long-jump to @code{sym2}. The original @samp{.word}
6490 contains @code{sym1} minus the address of the long-jump to
6493 If there were several occurrences of @samp{.word sym1-sym2} before the
6494 secondary jump table, all of them are adjusted. If there was a
6495 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
6496 long-jump to @code{sym4} is included in the secondary jump table,
6497 and the @code{.word} directives are adjusted to contain @code{sym3}
6498 minus the address of the long-jump to @code{sym4}; and so on, for as many
6499 entries in the original jump table as necessary.
6502 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
6503 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
6504 assembly language programmers.
6507 @c end DIFF-TBL-KLUGE
6510 @section Deprecated Directives
6512 @cindex deprecated directives
6513 @cindex obsolescent directives
6514 One day these directives won't work.
6515 They are included for compatibility with older assemblers.
6522 @node Object Attributes
6523 @chapter Object Attributes
6524 @cindex object attributes
6526 @command{@value{AS}} assembles source files written for a specific architecture
6527 into object files for that architecture. But not all object files are alike.
6528 Many architectures support incompatible variations. For instance, floating
6529 point arguments might be passed in floating point registers if the object file
6530 requires hardware floating point support---or floating point arguments might be
6531 passed in integer registers if the object file supports processors with no
6532 hardware floating point unit. Or, if two objects are built for different
6533 generations of the same architecture, the combination may require the
6534 newer generation at run-time.
6536 This information is useful during and after linking. At link time,
6537 @command{@value{LD}} can warn about incompatible object files. After link
6538 time, tools like @command{gdb} can use it to process the linked file
6541 Compatibility information is recorded as a series of object attributes. Each
6542 attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
6543 string, and indicates who sets the meaning of the tag. The tag is an integer,
6544 and indicates what property the attribute describes. The value may be a string
6545 or an integer, and indicates how the property affects this object. Missing
6546 attributes are the same as attributes with a zero value or empty string value.
6548 Object attributes were developed as part of the ABI for the ARM Architecture.
6549 The file format is documented in @cite{ELF for the ARM Architecture}.
6552 * GNU Object Attributes:: @sc{gnu} Object Attributes
6553 * Defining New Object Attributes:: Defining New Object Attributes
6556 @node GNU Object Attributes
6557 @section @sc{gnu} Object Attributes
6559 The @code{.gnu_attribute} directive records an object attribute
6560 with vendor @samp{gnu}.
6562 Except for @samp{Tag_compatibility}, which has both an integer and a string for
6563 its value, @sc{gnu} attributes have a string value if the tag number is odd and
6564 an integer value if the tag number is even. The second bit (@code{@var{tag} &
6565 2} is set for architecture-independent attributes and clear for
6566 architecture-dependent ones.
6568 @subsection Common @sc{gnu} attributes
6570 These attributes are valid on all architectures.
6573 @item Tag_compatibility (32)
6574 The compatibility attribute takes an integer flag value and a vendor name. If
6575 the flag value is 0, the file is compatible with other toolchains. If it is 1,
6576 then the file is only compatible with the named toolchain. If it is greater
6577 than 1, the file can only be processed by other toolchains under some private
6578 arrangement indicated by the flag value and the vendor name.
6581 @subsection MIPS Attributes
6584 @item Tag_GNU_MIPS_ABI_FP (4)
6585 The floating-point ABI used by this object file. The value will be:
6589 0 for files not affected by the floating-point ABI.
6591 1 for files using the hardware floating-point with a standard double-precision
6594 2 for files using the hardware floating-point ABI with a single-precision FPU.
6596 3 for files using the software floating-point ABI.
6598 4 for files using the hardware floating-point ABI with 64-bit wide
6599 double-precision floating-point registers and 32-bit wide general
6604 @subsection PowerPC Attributes
6607 @item Tag_GNU_Power_ABI_FP (4)
6608 The floating-point ABI used by this object file. The value will be:
6612 0 for files not affected by the floating-point ABI.
6614 1 for files using double-precision hardware floating-point ABI.
6616 2 for files using the software floating-point ABI.
6618 3 for files using single-precision hardware floating-point ABI.
6621 @item Tag_GNU_Power_ABI_Vector (8)
6622 The vector ABI used by this object file. The value will be:
6626 0 for files not affected by the vector ABI.
6628 1 for files using general purpose registers to pass vectors.
6630 2 for files using AltiVec registers to pass vectors.
6632 3 for files using SPE registers to pass vectors.
6636 @node Defining New Object Attributes
6637 @section Defining New Object Attributes
6639 If you want to define a new @sc{gnu} object attribute, here are the places you
6640 will need to modify. New attributes should be discussed on the @samp{binutils}
6645 This manual, which is the official register of attributes.
6647 The header for your architecture @file{include/elf}, to define the tag.
6649 The @file{bfd} support file for your architecture, to merge the attribute
6650 and issue any appropriate link warnings.
6652 Test cases in @file{ld/testsuite} for merging and link warnings.
6654 @file{binutils/readelf.c} to display your attribute.
6656 GCC, if you want the compiler to mark the attribute automatically.
6662 @node Machine Dependencies
6663 @chapter Machine Dependent Features
6665 @cindex machine dependencies
6666 The machine instruction sets are (almost by definition) different on
6667 each machine where @command{@value{AS}} runs. Floating point representations
6668 vary as well, and @command{@value{AS}} often supports a few additional
6669 directives or command-line options for compatibility with other
6670 assemblers on a particular platform. Finally, some versions of
6671 @command{@value{AS}} support special pseudo-instructions for branch
6674 This chapter discusses most of these differences, though it does not
6675 include details on any machine's instruction set. For details on that
6676 subject, see the hardware manufacturer's manual.
6680 * Alpha-Dependent:: Alpha Dependent Features
6683 * ARC-Dependent:: ARC Dependent Features
6686 * ARM-Dependent:: ARM Dependent Features
6689 * AVR-Dependent:: AVR Dependent Features
6692 * BFIN-Dependent:: BFIN Dependent Features
6695 * CR16-Dependent:: CR16 Dependent Features
6698 * CRIS-Dependent:: CRIS Dependent Features
6701 * D10V-Dependent:: D10V Dependent Features
6704 * D30V-Dependent:: D30V Dependent Features
6707 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6710 * HPPA-Dependent:: HPPA Dependent Features
6713 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
6716 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
6719 * i860-Dependent:: Intel 80860 Dependent Features
6722 * i960-Dependent:: Intel 80960 Dependent Features
6725 * IA-64-Dependent:: Intel IA-64 Dependent Features
6728 * IP2K-Dependent:: IP2K Dependent Features
6731 * LM32-Dependent:: LM32 Dependent Features
6734 * M32C-Dependent:: M32C Dependent Features
6737 * M32R-Dependent:: M32R Dependent Features
6740 * M68K-Dependent:: M680x0 Dependent Features
6743 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
6746 * MIPS-Dependent:: MIPS Dependent Features
6749 * MMIX-Dependent:: MMIX Dependent Features
6752 * MSP430-Dependent:: MSP430 Dependent Features
6755 * SH-Dependent:: Renesas / SuperH SH Dependent Features
6756 * SH64-Dependent:: SuperH SH64 Dependent Features
6759 * PDP-11-Dependent:: PDP-11 Dependent Features
6762 * PJ-Dependent:: picoJava Dependent Features
6765 * PPC-Dependent:: PowerPC Dependent Features
6769 * SCORE-Dependent:: SCORE Dependent Features
6773 * S/390-Dependent:: IBM S/390 Dependent Features
6777 * Sparc-Dependent:: SPARC Dependent Features
6780 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
6783 * V850-Dependent:: V850 Dependent Features
6786 * Xtensa-Dependent:: Xtensa Dependent Features
6789 * Z80-Dependent:: Z80 Dependent Features
6792 * Z8000-Dependent:: Z8000 Dependent Features
6795 * Vax-Dependent:: VAX Dependent Features
6802 @c The following major nodes are *sections* in the GENERIC version, *chapters*
6803 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
6804 @c peculiarity: to preserve cross-references, there must be a node called
6805 @c "Machine Dependencies". Hence the conditional nodenames in each
6806 @c major node below. Node defaulting in makeinfo requires adjacency of
6807 @c node and sectioning commands; hence the repetition of @chapter BLAH
6808 @c in both conditional blocks.
6811 @include c-alpha.texi
6827 @include c-bfin.texi
6831 @include c-cr16.texi
6835 @include c-cris.texi
6840 @node Machine Dependencies
6841 @chapter Machine Dependent Features
6843 The machine instruction sets are different on each Renesas chip family,
6844 and there are also some syntax differences among the families. This
6845 chapter describes the specific @command{@value{AS}} features for each
6849 * H8/300-Dependent:: Renesas H8/300 Dependent Features
6850 * SH-Dependent:: Renesas SH Dependent Features
6857 @include c-d10v.texi
6861 @include c-d30v.texi
6865 @include c-h8300.texi
6869 @include c-hppa.texi
6873 @include c-i370.texi
6877 @include c-i386.texi
6881 @include c-i860.texi
6885 @include c-i960.texi
6889 @include c-ia64.texi
6893 @include c-ip2k.texi
6897 @include c-lm32.texi
6901 @include c-m32c.texi
6905 @include c-m32r.texi
6909 @include c-m68k.texi
6913 @include c-m68hc11.texi
6917 @include c-mips.texi
6921 @include c-mmix.texi
6925 @include c-msp430.texi
6929 @include c-ns32k.texi
6933 @include c-pdp11.texi
6946 @include c-score.texi
6951 @include c-s390.texi
6957 @include c-sh64.texi
6961 @include c-sparc.texi
6965 @include c-tic54x.texi
6981 @include c-v850.texi
6985 @include c-xtensa.texi
6989 @c reverse effect of @down at top of generic Machine-Dep chapter
6993 @node Reporting Bugs
6994 @chapter Reporting Bugs
6995 @cindex bugs in assembler
6996 @cindex reporting bugs in assembler
6998 Your bug reports play an essential role in making @command{@value{AS}} reliable.
7000 Reporting a bug may help you by bringing a solution to your problem, or it may
7001 not. But in any case the principal function of a bug report is to help the
7002 entire community by making the next version of @command{@value{AS}} work better.
7003 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
7005 In order for a bug report to serve its purpose, you must include the
7006 information that enables us to fix the bug.
7009 * Bug Criteria:: Have you found a bug?
7010 * Bug Reporting:: How to report bugs
7014 @section Have You Found a Bug?
7015 @cindex bug criteria
7017 If you are not sure whether you have found a bug, here are some guidelines:
7020 @cindex fatal signal
7021 @cindex assembler crash
7022 @cindex crash of assembler
7024 If the assembler gets a fatal signal, for any input whatever, that is a
7025 @command{@value{AS}} bug. Reliable assemblers never crash.
7027 @cindex error on valid input
7029 If @command{@value{AS}} produces an error message for valid input, that is a bug.
7031 @cindex invalid input
7033 If @command{@value{AS}} does not produce an error message for invalid input, that
7034 is a bug. However, you should note that your idea of ``invalid input'' might
7035 be our idea of ``an extension'' or ``support for traditional practice''.
7038 If you are an experienced user of assemblers, your suggestions for improvement
7039 of @command{@value{AS}} are welcome in any case.
7043 @section How to Report Bugs
7045 @cindex assembler bugs, reporting
7047 A number of companies and individuals offer support for @sc{gnu} products. If
7048 you obtained @command{@value{AS}} from a support organization, we recommend you
7049 contact that organization first.
7051 You can find contact information for many support companies and
7052 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
7056 In any event, we also recommend that you send bug reports for @command{@value{AS}}
7060 The fundamental principle of reporting bugs usefully is this:
7061 @strong{report all the facts}. If you are not sure whether to state a
7062 fact or leave it out, state it!
7064 Often people omit facts because they think they know what causes the problem
7065 and assume that some details do not matter. Thus, you might assume that the
7066 name of a symbol you use in an example does not matter. Well, probably it does
7067 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
7068 happens to fetch from the location where that name is stored in memory;
7069 perhaps, if the name were different, the contents of that location would fool
7070 the assembler into doing the right thing despite the bug. Play it safe and
7071 give a specific, complete example. That is the easiest thing for you to do,
7072 and the most helpful.
7074 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
7075 it is new to us. Therefore, always write your bug reports on the assumption
7076 that the bug has not been reported previously.
7078 Sometimes people give a few sketchy facts and ask, ``Does this ring a
7079 bell?'' This cannot help us fix a bug, so it is basically useless. We
7080 respond by asking for enough details to enable us to investigate.
7081 You might as well expedite matters by sending them to begin with.
7083 To enable us to fix the bug, you should include all these things:
7087 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
7088 it with the @samp{--version} argument.
7090 Without this, we will not know whether there is any point in looking for
7091 the bug in the current version of @command{@value{AS}}.
7094 Any patches you may have applied to the @command{@value{AS}} source.
7097 The type of machine you are using, and the operating system name and
7101 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
7105 The command arguments you gave the assembler to assemble your example and
7106 observe the bug. To guarantee you will not omit something important, list them
7107 all. A copy of the Makefile (or the output from make) is sufficient.
7109 If we were to try to guess the arguments, we would probably guess wrong
7110 and then we might not encounter the bug.
7113 A complete input file that will reproduce the bug. If the bug is observed when
7114 the assembler is invoked via a compiler, send the assembler source, not the
7115 high level language source. Most compilers will produce the assembler source
7116 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
7117 the options @samp{-v --save-temps}; this will save the assembler source in a
7118 file with an extension of @file{.s}, and also show you exactly how
7119 @command{@value{AS}} is being run.
7122 A description of what behavior you observe that you believe is
7123 incorrect. For example, ``It gets a fatal signal.''
7125 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
7126 will certainly notice it. But if the bug is incorrect output, we might not
7127 notice unless it is glaringly wrong. You might as well not give us a chance to
7130 Even if the problem you experience is a fatal signal, you should still say so
7131 explicitly. Suppose something strange is going on, such as, your copy of
7132 @command{@value{AS}} is out of sync, or you have encountered a bug in the C
7133 library on your system. (This has happened!) Your copy might crash and ours
7134 would not. If you told us to expect a crash, then when ours fails to crash, we
7135 would know that the bug was not happening for us. If you had not told us to
7136 expect a crash, then we would not be able to draw any conclusion from our
7140 If you wish to suggest changes to the @command{@value{AS}} source, send us context
7141 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
7142 option. Always send diffs from the old file to the new file. If you even
7143 discuss something in the @command{@value{AS}} source, refer to it by context, not
7146 The line numbers in our development sources will not match those in your
7147 sources. Your line numbers would convey no useful information to us.
7150 Here are some things that are not necessary:
7154 A description of the envelope of the bug.
7156 Often people who encounter a bug spend a lot of time investigating
7157 which changes to the input file will make the bug go away and which
7158 changes will not affect it.
7160 This is often time consuming and not very useful, because the way we
7161 will find the bug is by running a single example under the debugger
7162 with breakpoints, not by pure deduction from a series of examples.
7163 We recommend that you save your time for something else.
7165 Of course, if you can find a simpler example to report @emph{instead}
7166 of the original one, that is a convenience for us. Errors in the
7167 output will be easier to spot, running under the debugger will take
7168 less time, and so on.
7170 However, simplification is not vital; if you do not want to do this,
7171 report the bug anyway and send us the entire test case you used.
7174 A patch for the bug.
7176 A patch for the bug does help us if it is a good one. But do not omit
7177 the necessary information, such as the test case, on the assumption that
7178 a patch is all we need. We might see problems with your patch and decide
7179 to fix the problem another way, or we might not understand it at all.
7181 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
7182 construct an example that will make the program follow a certain path through
7183 the code. If you do not send us the example, we will not be able to construct
7184 one, so we will not be able to verify that the bug is fixed.
7186 And if we cannot understand what bug you are trying to fix, or why your
7187 patch should be an improvement, we will not install it. A test case will
7188 help us to understand.
7191 A guess about what the bug is or what it depends on.
7193 Such guesses are usually wrong. Even we cannot guess right about such
7194 things without first using the debugger to find the facts.
7197 @node Acknowledgements
7198 @chapter Acknowledgements
7200 If you have contributed to GAS and your name isn't listed here,
7201 it is not meant as a slight. We just don't know about it. Send mail to the
7202 maintainer, and we'll correct the situation. Currently
7204 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
7206 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
7209 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
7210 information and the 68k series machines, most of the preprocessing pass, and
7211 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
7213 K. Richard Pixley maintained GAS for a while, adding various enhancements and
7214 many bug fixes, including merging support for several processors, breaking GAS
7215 up to handle multiple object file format back ends (including heavy rewrite,
7216 testing, an integration of the coff and b.out back ends), adding configuration
7217 including heavy testing and verification of cross assemblers and file splits
7218 and renaming, converted GAS to strictly ANSI C including full prototypes, added
7219 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
7220 port (including considerable amounts of reverse engineering), a SPARC opcode
7221 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
7222 assertions and made them work, much other reorganization, cleanup, and lint.
7224 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
7225 in format-specific I/O modules.
7227 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
7228 has done much work with it since.
7230 The Intel 80386 machine description was written by Eliot Dresselhaus.
7232 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
7234 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
7235 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
7237 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
7238 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
7239 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
7240 support a.out format.
7242 Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
7243 tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
7244 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
7245 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
7248 John Gilmore built the AMD 29000 support, added @code{.include} support, and
7249 simplified the configuration of which versions accept which directives. He
7250 updated the 68k machine description so that Motorola's opcodes always produced
7251 fixed-size instructions (e.g., @code{jsr}), while synthetic instructions
7252 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
7253 cross-compilation support, and one bug in relaxation that took a week and
7254 required the proverbial one-bit fix.
7256 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
7257 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
7258 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
7259 PowerPC assembler, and made a few other minor patches.
7261 Steve Chamberlain made GAS able to generate listings.
7263 Hewlett-Packard contributed support for the HP9000/300.
7265 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
7266 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
7267 formats). This work was supported by both the Center for Software Science at
7268 the University of Utah and Cygnus Support.
7270 Support for ELF format files has been worked on by Mark Eichin of Cygnus
7271 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
7272 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
7273 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
7274 and some initial 64-bit support).
7276 Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture.
7278 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
7279 support for openVMS/Alpha.
7281 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
7284 David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica,
7285 Inc.@: added support for Xtensa processors.
7287 Several engineers at Cygnus Support have also provided many small bug fixes and
7288 configuration enhancements.
7290 Jon Beniston added support for the Lattice Mico32 architecture.
7292 Many others have contributed large or small bugfixes and enhancements. If
7293 you have contributed significant work and are not mentioned on this list, and
7294 want to be, let us know. Some of the history has been lost; we are not
7295 intentionally leaving anyone out.
7297 @node GNU Free Documentation License
7298 @appendix GNU Free Documentation License
7302 @unnumbered AS Index
projects / deliverable / binutils-gdb.git / blob