1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 98, 2000
3 @c Free Software Foundation, Inc.
4 @c UPDATE!! On future updates--
5 @c (1) check for new machine-dep cmdline options in
6 @c md_parse_option definitions in config/tc-*.c
7 @c (2) for platform-specific directives, examine md_pseudo_op
9 @c (3) for object-format specific directives, examine obj_pseudo_op
11 @c (4) portable directives in potable[] in read.c
15 @c defaults, config file may override:
18 @include asconfig.texi
21 @c common OR combinations of conditions
41 @set abnormal-separator
45 @settitle Using @value{AS}
48 @settitle Using @value{AS} (@value{TARGET})
50 @setchapternewpage odd
55 @c WARE! Some of the machine-dependent sections contain tables of machine
56 @c instructions. Except in multi-column format, these tables look silly.
57 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
58 @c the multi-col format is faked within @example sections.
60 @c Again unfortunately, the natural size that fits on a page, for these tables,
61 @c is different depending on whether or not smallbook is turned on.
62 @c This matters, because of order: text flow switches columns at each page
65 @c The format faked in this source works reasonably well for smallbook,
66 @c not well for the default large-page format. This manual expects that if you
67 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
68 @c tables in question. You can turn on one without the other at your
69 @c discretion, of course.
72 @c the insn tables look just as silly in info files regardless of smallbook,
73 @c might as well show 'em anyways.
79 * As: (as). The GNU assembler.
88 This file documents the GNU Assembler "@value{AS}".
90 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
92 Permission is granted to copy, distribute and/or modify this document
93 under the terms of the GNU Free Documentation License, Version 1.1
94 or any later version published by the Free Software Foundation;
95 with no Invariant Sections, with no Front-Cover Texts, and with no
96 Back-Cover Texts. A copy of the license is included in the
97 section entitled "GNU Free Documentation License".
100 Permission is granted to process this file through Tex and print the
101 results, provided the printed document carries copying permission
102 notice identical to this one except for the removal of this paragraph
103 (this paragraph not being relevant to the printed manual).
109 @title Using @value{AS}
110 @subtitle The @sc{gnu} Assembler
112 @subtitle for the @value{TARGET} family
115 @subtitle Version @value{VERSION}
118 The Free Software Foundation Inc. thanks The Nice Computer
119 Company of Australia for loaning Dean Elsner to write the
120 first (Vax) version of @code{as} for Project @sc{gnu}.
121 The proprietors, management and staff of TNCCA thank FSF for
122 distracting the boss while they got some work
125 @author Dean Elsner, Jay Fenlason & friends
129 \hfill {\it Using {\tt @value{AS}}}\par
130 \hfill Edited by Cygnus Support\par
132 %"boxit" macro for figures:
133 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
134 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
135 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
136 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
137 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
140 @vskip 0pt plus 1filll
141 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
143 Permission is granted to copy, distribute and/or modify this document
144 under the terms of the GNU Free Documentation License, Version 1.1
145 or any later version published by the Free Software Foundation;
146 with no Invariant Sections, with no Front-Cover Texts, and with no
147 Back-Cover Texts. A copy of the license is included in the
148 section entitled "GNU Free Documentation License".
154 @top Using @value{AS}
156 This file is a user guide to the @sc{gnu} assembler @code{@value{AS}} version
159 This version of the file describes @code{@value{AS}} configured to generate
160 code for @value{TARGET} architectures.
163 This document is distributed under the terms of the GNU Free
164 Documentation License. A copy of the license is included in the
165 section entitled "GNU Free Documentation License".
168 * Overview:: Overview
169 * Invoking:: Command-Line Options
171 * Sections:: Sections and Relocation
173 * Expressions:: Expressions
174 * Pseudo Ops:: Assembler Directives
175 * Machine Dependencies:: Machine Dependent Features
176 * Reporting Bugs:: Reporting Bugs
177 * Acknowledgements:: Who Did What
178 * GNU Free Documentation License:: GNU Free Documentation License
186 This manual is a user guide to the @sc{gnu} assembler @code{@value{AS}}.
188 This version of the manual describes @code{@value{AS}} configured to generate
189 code for @value{TARGET} architectures.
193 @cindex invocation summary
194 @cindex option summary
195 @cindex summary of options
196 Here is a brief summary of how to invoke @code{@value{AS}}. For details,
197 @pxref{Invoking,,Comand-Line Options}.
199 @c We don't use deffn and friends for the following because they seem
200 @c to be limited to one line for the header.
202 @value{AS} [ -a[cdhlns][=file] ] [ -D ] [ --defsym @var{sym}=@var{val} ]
203 [ -f ] [ --gstabs ] [ --gdwarf2 ] [ --help ] [ -I @var{dir} ] [ -J ] [ -K ] [ -L ]
204 [ --keep-locals ] [ -o @var{objfile} ] [ -R ] [ --statistics ] [ -v ]
205 [ -version ] [ --version ] [ -W ] [ --warn ] [ --fatal-warnings ]
206 [ -w ] [ -x ] [ -Z ] [ --target-help ]
208 @c am29k has no machine-dependent assembler options
211 [ -mbig-endian | -mlittle-endian ]
214 [ -m[arm]1 | -m[arm]2 | -m[arm]250 | -m[arm]3 | -m[arm]6 | -m[arm]60 |
215 -m[arm]600 | -m[arm]610 | -m[arm]620 | -m[arm]7[t][[d]m[i]][fe] | -m[arm]70 |
216 -m[arm]700 | -m[arm]710[c] | -m[arm]7100 | -m[arm]7500 | -m[arm]8 |
217 -m[arm]810 | -m[arm]9 | -m[arm]920 | -m[arm]920t | -m[arm]9tdmi |
218 -mstrongarm | -mstrongarm110 | -mstrongarm1100 ]
219 [ -m[arm]v2 | -m[arm]v2a | -m[arm]v3 | -m[arm]v3m | -m[arm]v4 | -m[arm]v4t |
220 -m[arm]v5 | -[arm]v5t ]
222 [ -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu ]
224 [ -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant ]
225 [ -mthumb-interwork ]
236 @c Hitachi family chips have no machine-dependent assembler options
239 @c HPPA has no machine-dependent assembler options (yet).
245 @c The order here is important. See c-sparc.texi.
246 [ -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
247 -Av8plus | -Av8plusa | -Av9 | -Av9a ]
248 [ -xarch=v8plus | -xarch=v8plusa ] [ -bump ] [ -32 | -64 ]
251 [ -mcpu=54[123589] | -mcpu=54[56]lp ] [ -mfar-mode | -mf ]
252 [ -merrors-to-file <filename> | -me <filename> ]
255 @c Z8000 has no machine-dependent assembler options
258 @c see md_parse_option in tc-i960.c
259 [ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC ]
263 [ --m32rx | --[no-]warn-explicit-parallel-conflicts | --W[n]p ]
266 [ -l ] [ -m68000 | -m68010 | -m68020 | ... ]
269 [ -jsri2bsr ] [ -sifilter ] [ -relax ]
273 [ -m68hc11 | -m68hc12 ]
274 [ --force-long-branchs ] [ --short-branchs ] [ --strict-direct-mode ]
275 [ --print-insn-syntax ] [ --print-opcodes ] [ --generate-example ]
278 [ -nocpp ] [ -EL ] [ -EB ] [ -G @var{num} ] [ -mcpu=@var{CPU} ]
279 [ -mips1 ] [ -mips2 ] [ -mips3 ] [ -mips4 ] [ -mips5 ]
280 [ -mips32 ] [ -mips64 ]
281 [ -m4650 ] [ -no-m4650 ]
282 [ --trap ] [ --break ]
283 [ --emulation=@var{name} ]
285 [ -- | @var{files} @dots{} ]
290 Turn on listings, in any of a variety of ways:
294 omit false conditionals
297 omit debugging directives
300 include high-level source
306 include macro expansions
309 omit forms processing
315 set the name of the listing file
318 You may combine these options; for example, use @samp{-aln} for assembly
319 listing without forms processing. The @samp{=file} option, if used, must be
320 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
323 Ignored. This option is accepted for script compatibility with calls to
326 @item --defsym @var{sym}=@var{value}
327 Define the symbol @var{sym} to be @var{value} before assembling the input file.
328 @var{value} must be an integer constant. As in C, a leading @samp{0x}
329 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
332 ``fast''---skip whitespace and comment preprocessing (assume source is
336 Generate stabs debugging information for each assembler line. This
337 may help debugging assembler code, if the debugger can handle it.
340 Generate DWARF2 debugging information for each assembler line. This
341 may help debugging assembler code, if the debugger can handle it. Note - this
342 option is only supported by some targets, not all of them.
345 Print a summary of the command line options and exit.
348 Print a summary of all target specific options and exit.
351 Add directory @var{dir} to the search list for @code{.include} directives.
354 Don't warn about signed overflow.
357 @ifclear DIFF-TBL-KLUGE
358 This option is accepted but has no effect on the @value{TARGET} family.
360 @ifset DIFF-TBL-KLUGE
361 Issue warnings when difference tables altered for long displacements.
366 Keep (in the symbol table) local symbols. On traditional a.out systems
367 these start with @samp{L}, but different systems have different local
370 @item -o @var{objfile}
371 Name the object-file output from @code{@value{AS}} @var{objfile}.
374 Fold the data section into the text section.
377 Print the maximum space (in bytes) and total time (in seconds) used by
380 @item --strip-local-absolute
381 Remove local absolute symbols from the outgoing symbol table.
385 Print the @code{as} version.
388 Print the @code{as} version and exit.
392 Suppress warning messages.
394 @item --fatal-warnings
395 Treat warnings as errors.
398 Don't suppress warning messages or treat them as errors.
407 Generate an object file even after errors.
409 @item -- | @var{files} @dots{}
410 Standard input, or source files to assemble.
415 The following options are available when @value{AS} is configured for
420 @cindex ARC endianness
421 @cindex endianness, ARC
422 @cindex big endian output, ARC
424 Generate ``big endian'' format output.
426 @cindex little endian output, ARC
427 @item -mlittle-endian
428 Generate ``little endian'' format output.
434 The following options are available when @value{AS} is configured for the ARM
438 @item -m[arm][1|2|3|6|7|8|9][...]
439 Specify which ARM processor variant is the target.
440 @item -m[arm]v[2|2a|3|3m|4|4t|5|5t]
441 Specify which ARM architecture variant is used by the target.
442 @item -mthumb | -mall
443 Enable or disable Thumb only instruction decoding.
444 @item -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu
445 Select which Floating Point architcture is the target.
446 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
447 Select which procedure calling convention is in use.
449 Select either big-endian (-EB) or little-endian (-EL) output.
450 @item -mthumb-interwork
451 Specify that the code has been generated with interworking between Thumb and
454 Specify that PIC code has been generated.
459 The following options are available when @value{AS} is configured for
462 @cindex D10V optimization
463 @cindex optimization, D10V
465 Optimize output by parallelizing instructions.
470 The following options are available when @value{AS} is configured for a D30V
473 @cindex D30V optimization
474 @cindex optimization, D30V
476 Optimize output by parallelizing instructions.
480 Warn when nops are generated.
482 @cindex D30V nops after 32-bit multiply
484 Warn when a nop after a 32-bit multiply instruction is generated.
489 The following options are available when @value{AS} is configured for the
490 Intel 80960 processor.
493 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
494 Specify which variant of the 960 architecture is the target.
497 Add code to collect statistics about branches taken.
500 Do not alter compare-and-branch instructions for long displacements;
507 The following options are available when @value{AS} is configured for the
508 Mitsubishi M32R series.
513 Specify which processor in the M32R family is the target. The default
514 is normally the M32R, but this option changes it to the M32RX.
516 @item --warn-explicit-parallel-conflicts or --Wp
517 Produce warning messages when questionable parallel constructs are
520 @item --no-warn-explicit-parallel-conflicts or --Wnp
521 Do not produce warning messages when questionable parallel constructs are
528 The following options are available when @value{AS} is configured for the
529 Motorola 68000 series.
534 Shorten references to undefined symbols, to one word instead of two.
536 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 | -m68040 | -m68060
537 @itemx | -m68302 | -m68331 | -m68332 | -m68333 | -m68340 | -mcpu32 | -m5200
538 Specify what processor in the 68000 family is the target. The default
539 is normally the 68020, but this can be changed at configuration time.
541 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
542 The target machine does (or does not) have a floating-point coprocessor.
543 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
544 the basic 68000 is not compatible with the 68881, a combination of the
545 two can be specified, since it's possible to do emulation of the
546 coprocessor instructions with the main processor.
548 @item -m68851 | -mno-68851
549 The target machine does (or does not) have a memory-management
550 unit coprocessor. The default is to assume an MMU for 68020 and up.
556 The following options are available when @value{AS} is configured for
557 a picoJava processor.
561 @cindex PJ endianness
562 @cindex endianness, PJ
563 @cindex big endian output, PJ
565 Generate ``big endian'' format output.
567 @cindex little endian output, PJ
569 Generate ``little endian'' format output.
575 The following options are available when @value{AS} is configured for the
576 Motorola 68HC11 or 68HC12 series.
580 @item -m68hc11 | -m68hc12
581 Specify what processor is the target. The default is
582 defined by the configuration option when building the assembler.
584 @item --force-long-branchs
585 Relative branches are turned into absolute ones. This concerns
586 conditional branches, unconditional branches and branches to a
589 @item -S | --short-branchs
590 Do not turn relative branchs into absolute ones
591 when the offset is out of range.
593 @item --strict-direct-mode
594 Do not turn the direct addressing mode into extended addressing mode
595 when the instruction does not support direct addressing mode.
597 @item --print-insn-syntax
598 Print the syntax of instruction in case of error.
600 @item --print-opcodes
601 print the list of instructions with syntax and then exit.
603 @item --generate-example
604 print an example of instruction for each possible instruction and then exit.
605 This option is only useful for testing @code{@value{AS}}.
611 The following options are available when @code{@value{AS}} is configured
612 for the SPARC architecture:
615 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
616 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
617 Explicitly select a variant of the SPARC architecture.
619 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
620 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
622 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
623 UltraSPARC extensions.
625 @item -xarch=v8plus | -xarch=v8plusa
626 For compatibility with the Solaris v9 assembler. These options are
627 equivalent to -Av8plus and -Av8plusa, respectively.
630 Warn when the assembler switches to another architecture.
635 The following options are available when @value{AS} is configured for the 'c54x
640 Enable extended addressing mode. All addresses and relocations will assume
641 extended addressing (usually 23 bits).
642 @item -mcpu=@var{CPU_VERSION}
643 Sets the CPU version being compiled for.
644 @item -merrors-to-file @var{FILENAME}
645 Redirect error output to a file, for broken systems which don't support such
646 behaviour in the shell.
651 The following options are available when @value{AS} is configured for
656 This option sets the largest size of an object that can be referenced
657 implicitly with the @code{gp} register. It is only accepted for targets that
658 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
660 @cindex MIPS endianness
661 @cindex endianness, MIPS
662 @cindex big endian output, MIPS
664 Generate ``big endian'' format output.
666 @cindex little endian output, MIPS
668 Generate ``little endian'' format output.
676 Generate code for a particular MIPS Instruction Set Architecture level.
677 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
678 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
680 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
681 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
682 processors, respectively.
686 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
687 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
688 instructions around accesses to the @samp{HI} and @samp{LO} registers.
689 @samp{-no-m4650} turns off this option.
691 @item -mcpu=@var{CPU}
692 Generate code for a particular MIPS cpu. It is exactly equivalent to
693 @samp{-m@var{cpu}}, except that there are more value of @var{cpu}
697 @item --emulation=@var{name}
698 This option causes @code{@value{AS}} to emulate @code{@value{AS}} configured
699 for some other target, in all respects, including output format (choosing
700 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
701 debugging information or store symbol table information, and default
702 endianness. The available configuration names are: @samp{mipsecoff},
703 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
704 @samp{mipsbelf}. The first two do not alter the default endianness from that
705 of the primary target for which the assembler was configured; the others change
706 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
707 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
708 selection in any case.
710 This option is currently supported only when the primary target
711 @code{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
712 Furthermore, the primary target or others specified with
713 @samp{--enable-targets=@dots{}} at configuration time must include support for
714 the other format, if both are to be available. For example, the Irix 5
715 configuration includes support for both.
717 Eventually, this option will support more configurations, with more
718 fine-grained control over the assembler's behavior, and will be supported for
722 @code{@value{AS}} ignores this option. It is accepted for compatibility with
730 Control how to deal with multiplication overflow and division by zero.
731 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
732 (and only work for Instruction Set Architecture level 2 and higher);
733 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
739 The following options are available when @value{AS} is configured for
745 Enable or disable the JSRI to BSR transformation. By default this is enabled.
746 The command line option @samp{-nojsri2bsr} can be used to disable it.
750 Enable or disable the silicon filter behaviour. By default this is disabled.
751 The default can be overidden by the @samp{-sifilter} command line option.
754 Alter jump instructions for long displacements.
756 @item -mcpu=[210|340]
757 Select the cpu type on the target hardware. This controls which instructions
761 Assemble for a big endian target.
764 Assemble for a little endian target.
770 * Manual:: Structure of this Manual
771 * GNU Assembler:: The GNU Assembler
772 * Object Formats:: Object File Formats
773 * Command Line:: Command Line
774 * Input Files:: Input Files
775 * Object:: Output (Object) File
776 * Errors:: Error and Warning Messages
780 @section Structure of this Manual
782 @cindex manual, structure and purpose
783 This manual is intended to describe what you need to know to use
784 @sc{gnu} @code{@value{AS}}. We cover the syntax expected in source files, including
785 notation for symbols, constants, and expressions; the directives that
786 @code{@value{AS}} understands; and of course how to invoke @code{@value{AS}}.
789 We also cover special features in the @value{TARGET}
790 configuration of @code{@value{AS}}, including assembler directives.
793 This manual also describes some of the machine-dependent features of
794 various flavors of the assembler.
797 @cindex machine instructions (not covered)
798 On the other hand, this manual is @emph{not} intended as an introduction
799 to programming in assembly language---let alone programming in general!
800 In a similar vein, we make no attempt to introduce the machine
801 architecture; we do @emph{not} describe the instruction set, standard
802 mnemonics, registers or addressing modes that are standard to a
803 particular architecture.
805 You may want to consult the manufacturer's
806 machine architecture manual for this information.
810 For information on the H8/300 machine instruction set, see @cite{H8/300
811 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
812 see @cite{H8/300H Series Programming Manual} (Hitachi).
815 For information on the H8/500 machine instruction set, see @cite{H8/500
816 Series Programming Manual} (Hitachi M21T001).
819 For information on the Hitachi SH machine instruction set, see
820 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
823 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
827 @c I think this is premature---doc@cygnus.com, 17jan1991
829 Throughout this manual, we assume that you are running @dfn{GNU},
830 the portable operating system from the @dfn{Free Software
831 Foundation, Inc.}. This restricts our attention to certain kinds of
832 computer (in particular, the kinds of computers that @sc{gnu} can run on);
833 once this assumption is granted examples and definitions need less
836 @code{@value{AS}} is part of a team of programs that turn a high-level
837 human-readable series of instructions into a low-level
838 computer-readable series of instructions. Different versions of
839 @code{@value{AS}} are used for different kinds of computer.
842 @c There used to be a section "Terminology" here, which defined
843 @c "contents", "byte", "word", and "long". Defining "word" to any
844 @c particular size is confusing when the .word directive may generate 16
845 @c bits on one machine and 32 bits on another; in general, for the user
846 @c version of this manual, none of these terms seem essential to define.
847 @c They were used very little even in the former draft of the manual;
848 @c this draft makes an effort to avoid them (except in names of
852 @section The GNU Assembler
854 @sc{gnu} @code{as} is really a family of assemblers.
856 This manual describes @code{@value{AS}}, a member of that family which is
857 configured for the @value{TARGET} architectures.
859 If you use (or have used) the @sc{gnu} assembler on one architecture, you
860 should find a fairly similar environment when you use it on another
861 architecture. Each version has much in common with the others,
862 including object file formats, most assembler directives (often called
863 @dfn{pseudo-ops}) and assembler syntax.@refill
865 @cindex purpose of @sc{gnu} assembler
866 @code{@value{AS}} is primarily intended to assemble the output of the
867 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
868 @code{@value{LD}}. Nevertheless, we've tried to make @code{@value{AS}}
869 assemble correctly everything that other assemblers for the same
870 machine would assemble.
872 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
875 @c This remark should appear in generic version of manual; assumption
876 @c here is that generic version sets M680x0.
877 This doesn't mean @code{@value{AS}} always uses the same syntax as another
878 assembler for the same architecture; for example, we know of several
879 incompatible versions of 680x0 assembly language syntax.
882 Unlike older assemblers, @code{@value{AS}} is designed to assemble a source
883 program in one pass of the source file. This has a subtle impact on the
884 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
887 @section Object File Formats
889 @cindex object file format
890 The @sc{gnu} assembler can be configured to produce several alternative
891 object file formats. For the most part, this does not affect how you
892 write assembly language programs; but directives for debugging symbols
893 are typically different in different file formats. @xref{Symbol
894 Attributes,,Symbol Attributes}.
897 On the @value{TARGET}, @code{@value{AS}} is configured to produce
898 @value{OBJ-NAME} format object files.
900 @c The following should exhaust all configs that set MULTI-OBJ, ideally
902 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
903 @code{a.out} or COFF format object files.
906 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
907 @code{b.out} or COFF format object files.
910 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
911 SOM or ELF format object files.
916 @section Command Line
918 @cindex command line conventions
919 After the program name @code{@value{AS}}, the command line may contain
920 options and file names. Options may appear in any order, and may be
921 before, after, or between file names. The order of file names is
924 @cindex standard input, as input file
926 @file{--} (two hyphens) by itself names the standard input file
927 explicitly, as one of the files for @code{@value{AS}} to assemble.
929 @cindex options, command line
930 Except for @samp{--} any command line argument that begins with a
931 hyphen (@samp{-}) is an option. Each option changes the behavior of
932 @code{@value{AS}}. No option changes the way another option works. An
933 option is a @samp{-} followed by one or more letters; the case of
934 the letter is important. All options are optional.
936 Some options expect exactly one file name to follow them. The file
937 name may either immediately follow the option's letter (compatible
938 with older assemblers) or it may be the next command argument (@sc{gnu}
939 standard). These two command lines are equivalent:
942 @value{AS} -o my-object-file.o mumble.s
943 @value{AS} -omy-object-file.o mumble.s
950 @cindex source program
952 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
953 describe the program input to one run of @code{@value{AS}}. The program may
954 be in one or more files; how the source is partitioned into files
955 doesn't change the meaning of the source.
957 @c I added "con" prefix to "catenation" just to prove I can overcome my
958 @c APL training... doc@cygnus.com
959 The source program is a concatenation of the text in all the files, in the
962 Each time you run @code{@value{AS}} it assembles exactly one source
963 program. The source program is made up of one or more files.
964 (The standard input is also a file.)
966 You give @code{@value{AS}} a command line that has zero or more input file
967 names. The input files are read (from left file name to right). A
968 command line argument (in any position) that has no special meaning
969 is taken to be an input file name.
971 If you give @code{@value{AS}} no file names it attempts to read one input file
972 from the @code{@value{AS}} standard input, which is normally your terminal. You
973 may have to type @key{ctl-D} to tell @code{@value{AS}} there is no more program
976 Use @samp{--} if you need to explicitly name the standard input file
977 in your command line.
979 If the source is empty, @code{@value{AS}} produces a small, empty object
982 @subheading Filenames and Line-numbers
984 @cindex input file linenumbers
985 @cindex line numbers, in input files
986 There are two ways of locating a line in the input file (or files) and
987 either may be used in reporting error messages. One way refers to a line
988 number in a physical file; the other refers to a line number in a
989 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
991 @dfn{Physical files} are those files named in the command line given
992 to @code{@value{AS}}.
994 @dfn{Logical files} are simply names declared explicitly by assembler
995 directives; they bear no relation to physical files. Logical file names help
996 error messages reflect the original source file, when @code{@value{AS}} source
997 is itself synthesized from other files. @code{@value{AS}} understands the
998 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
999 @ref{File,,@code{.file}}.
1002 @section Output (Object) File
1008 Every time you run @code{@value{AS}} it produces an output file, which is
1009 your assembly language program translated into numbers. This file
1010 is the object file. Its default name is
1018 @code{b.out} when @code{@value{AS}} is configured for the Intel 80960.
1020 You can give it another name by using the @code{-o} option. Conventionally,
1021 object file names end with @file{.o}. The default name is used for historical
1022 reasons: older assemblers were capable of assembling self-contained programs
1023 directly into a runnable program. (For some formats, this isn't currently
1024 possible, but it can be done for the @code{a.out} format.)
1028 The object file is meant for input to the linker @code{@value{LD}}. It contains
1029 assembled program code, information to help @code{@value{LD}} integrate
1030 the assembled program into a runnable file, and (optionally) symbolic
1031 information for the debugger.
1033 @c link above to some info file(s) like the description of a.out.
1034 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1037 @section Error and Warning Messages
1039 @cindex error messsages
1040 @cindex warning messages
1041 @cindex messages from assembler
1042 @code{@value{AS}} may write warnings and error messages to the standard error
1043 file (usually your terminal). This should not happen when a compiler
1044 runs @code{@value{AS}} automatically. Warnings report an assumption made so
1045 that @code{@value{AS}} could keep assembling a flawed program; errors report a
1046 grave problem that stops the assembly.
1048 @cindex format of warning messages
1049 Warning messages have the format
1052 file_name:@b{NNN}:Warning Message Text
1056 @cindex line numbers, in warnings/errors
1057 (where @b{NNN} is a line number). If a logical file name has been given
1058 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1059 the current input file is used. If a logical line number was given
1061 (@pxref{Line,,@code{.line}})
1065 (@pxref{Line,,@code{.line}})
1068 (@pxref{Ln,,@code{.ln}})
1071 then it is used to calculate the number printed,
1072 otherwise the actual line in the current source file is printed. The
1073 message text is intended to be self explanatory (in the grand Unix
1076 @cindex format of error messages
1077 Error messages have the format
1079 file_name:@b{NNN}:FATAL:Error Message Text
1081 The file name and line number are derived as for warning
1082 messages. The actual message text may be rather less explanatory
1083 because many of them aren't supposed to happen.
1086 @chapter Command-Line Options
1088 @cindex options, all versions of assembler
1089 This chapter describes command-line options available in @emph{all}
1090 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1092 to the @value{TARGET}.
1095 to particular machine architectures.
1098 If you are invoking @code{@value{AS}} via the @sc{gnu} C compiler (version 2),
1099 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1100 The assembler arguments must be separated from each other (and the @samp{-Wa})
1101 by commas. For example:
1104 gcc -c -g -O -Wa,-alh,-L file.c
1108 This passes two options to the assembler: @samp{-alh} (emit a listing to
1109 standard output with with high-level and assembly source) and @samp{-L} (retain
1110 local symbols in the symbol table).
1112 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1113 command-line options are automatically passed to the assembler by the compiler.
1114 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1115 precisely what options it passes to each compilation pass, including the
1119 * a:: -a[cdhlns] enable listings
1120 * D:: -D for compatibility
1121 * f:: -f to work faster
1122 * I:: -I for .include search path
1123 @ifclear DIFF-TBL-KLUGE
1124 * K:: -K for compatibility
1126 @ifset DIFF-TBL-KLUGE
1127 * K:: -K for difference tables
1130 * L:: -L to retain local labels
1131 * M:: -M or --mri to assemble in MRI compatibility mode
1132 * MD:: --MD for dependency tracking
1133 * o:: -o to name the object file
1134 * R:: -R to join data and text sections
1135 * statistics:: --statistics to see statistics about assembly
1136 * traditional-format:: --traditional-format for compatible output
1137 * v:: -v to announce version
1138 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1139 * Z:: -Z to make object file even after errors
1143 @section Enable Listings: @code{-a[cdhlns]}
1152 @cindex listings, enabling
1153 @cindex assembly listings, enabling
1155 These options enable listing output from the assembler. By itself,
1156 @samp{-a} requests high-level, assembly, and symbols listing.
1157 You can use other letters to select specific options for the list:
1158 @samp{-ah} requests a high-level language listing,
1159 @samp{-al} requests an output-program assembly listing, and
1160 @samp{-as} requests a symbol table listing.
1161 High-level listings require that a compiler debugging option like
1162 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1165 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1166 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1167 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1168 omitted from the listing.
1170 Use the @samp{-ad} option to omit debugging directives from the
1173 Once you have specified one of these options, you can further control
1174 listing output and its appearance using the directives @code{.list},
1175 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1177 The @samp{-an} option turns off all forms processing.
1178 If you do not request listing output with one of the @samp{-a} options, the
1179 listing-control directives have no effect.
1181 The letters after @samp{-a} may be combined into one option,
1182 @emph{e.g.}, @samp{-aln}.
1188 This option has no effect whatsoever, but it is accepted to make it more
1189 likely that scripts written for other assemblers also work with
1193 @section Work Faster: @code{-f}
1196 @cindex trusted compiler
1197 @cindex faster processing (@code{-f})
1198 @samp{-f} should only be used when assembling programs written by a
1199 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1200 and comment preprocessing on
1201 the input file(s) before assembling them. @xref{Preprocessing,
1205 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1206 preprocessed (if they contain comments, for example), @code{@value{AS}} does
1211 @section @code{.include} search path: @code{-I} @var{path}
1213 @kindex -I @var{path}
1214 @cindex paths for @code{.include}
1215 @cindex search path for @code{.include}
1216 @cindex @code{include} directive search path
1217 Use this option to add a @var{path} to the list of directories
1218 @code{@value{AS}} searches for files specified in @code{.include}
1219 directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as
1220 many times as necessary to include a variety of paths. The current
1221 working directory is always searched first; after that, @code{@value{AS}}
1222 searches any @samp{-I} directories in the same order as they were
1223 specified (left to right) on the command line.
1226 @section Difference Tables: @code{-K}
1229 @ifclear DIFF-TBL-KLUGE
1230 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1231 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1232 where it can be used to warn when the assembler alters the machine code
1233 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1234 family does not have the addressing limitations that sometimes lead to this
1235 alteration on other platforms.
1238 @ifset DIFF-TBL-KLUGE
1239 @cindex difference tables, warning
1240 @cindex warning for altered difference tables
1241 @code{@value{AS}} sometimes alters the code emitted for directives of the form
1242 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1243 You can use the @samp{-K} option if you want a warning issued when this
1248 @section Include Local Labels: @code{-L}
1251 @cindex local labels, retaining in output
1252 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1253 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1254 debugging, because they are intended for the use of programs (like
1255 compilers) that compose assembler programs, not for your notice.
1256 Normally both @code{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1257 normally debug with them.
1259 This option tells @code{@value{AS}} to retain those @samp{L@dots{}} symbols
1260 in the object file. Usually if you do this you also tell the linker
1261 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1263 By default, a local label is any label beginning with @samp{L}, but each
1264 target is allowed to redefine the local label prefix.
1266 On the HPPA local labels begin with @samp{L$}.
1270 @section Assemble in MRI Compatibility Mode: @code{-M}
1273 @cindex MRI compatibility mode
1274 The @code{-M} or @code{--mri} option selects MRI compatibility mode. This
1275 changes the syntax and pseudo-op handling of @code{@value{AS}} to make it
1276 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1277 configured target) assembler from Microtec Research. The exact nature of the
1278 MRI syntax will not be documented here; see the MRI manuals for more
1279 information. Note in particular that the handling of macros and macro
1280 arguments is somewhat different. The purpose of this option is to permit
1281 assembling existing MRI assembler code using @code{@value{AS}}.
1283 The MRI compatibility is not complete. Certain operations of the MRI assembler
1284 depend upon its object file format, and can not be supported using other object
1285 file formats. Supporting these would require enhancing each object file format
1286 individually. These are:
1289 @item global symbols in common section
1291 The m68k MRI assembler supports common sections which are merged by the linker.
1292 Other object file formats do not support this. @code{@value{AS}} handles
1293 common sections by treating them as a single common symbol. It permits local
1294 symbols to be defined within a common section, but it can not support global
1295 symbols, since it has no way to describe them.
1297 @item complex relocations
1299 The MRI assemblers support relocations against a negated section address, and
1300 relocations which combine the start addresses of two or more sections. These
1301 are not support by other object file formats.
1303 @item @code{END} pseudo-op specifying start address
1305 The MRI @code{END} pseudo-op permits the specification of a start address.
1306 This is not supported by other object file formats. The start address may
1307 instead be specified using the @code{-e} option to the linker, or in a linker
1310 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1312 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1313 name to the output file. This is not supported by other object file formats.
1315 @item @code{ORG} pseudo-op
1317 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1318 address. This differs from the usual @code{@value{AS}} @code{.org} pseudo-op,
1319 which changes the location within the current section. Absolute sections are
1320 not supported by other object file formats. The address of a section may be
1321 assigned within a linker script.
1324 There are some other features of the MRI assembler which are not supported by
1325 @code{@value{AS}}, typically either because they are difficult or because they
1326 seem of little consequence. Some of these may be supported in future releases.
1330 @item EBCDIC strings
1332 EBCDIC strings are not supported.
1334 @item packed binary coded decimal
1336 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1337 and @code{DCB.P} pseudo-ops are not supported.
1339 @item @code{FEQU} pseudo-op
1341 The m68k @code{FEQU} pseudo-op is not supported.
1343 @item @code{NOOBJ} pseudo-op
1345 The m68k @code{NOOBJ} pseudo-op is not supported.
1347 @item @code{OPT} branch control options
1349 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1350 @code{BRL}, and @code{BRW}---are ignored. @code{@value{AS}} automatically
1351 relaxes all branches, whether forward or backward, to an appropriate size, so
1352 these options serve no purpose.
1354 @item @code{OPT} list control options
1356 The following m68k @code{OPT} list control options are ignored: @code{C},
1357 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1358 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1360 @item other @code{OPT} options
1362 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1363 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1365 @item @code{OPT} @code{D} option is default
1367 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1368 @code{OPT NOD} may be used to turn it off.
1370 @item @code{XREF} pseudo-op.
1372 The m68k @code{XREF} pseudo-op is ignored.
1374 @item @code{.debug} pseudo-op
1376 The i960 @code{.debug} pseudo-op is not supported.
1378 @item @code{.extended} pseudo-op
1380 The i960 @code{.extended} pseudo-op is not supported.
1382 @item @code{.list} pseudo-op.
1384 The various options of the i960 @code{.list} pseudo-op are not supported.
1386 @item @code{.optimize} pseudo-op
1388 The i960 @code{.optimize} pseudo-op is not supported.
1390 @item @code{.output} pseudo-op
1392 The i960 @code{.output} pseudo-op is not supported.
1394 @item @code{.setreal} pseudo-op
1396 The i960 @code{.setreal} pseudo-op is not supported.
1401 @section Dependency tracking: @code{--MD}
1404 @cindex dependency tracking
1407 @code{@value{AS}} can generate a dependency file for the file it creates. This
1408 file consists of a single rule suitable for @code{make} describing the
1409 dependencies of the main source file.
1411 The rule is written to the file named in its argument.
1413 This feature is used in the automatic updating of makefiles.
1416 @section Name the Object File: @code{-o}
1419 @cindex naming object file
1420 @cindex object file name
1421 There is always one object file output when you run @code{@value{AS}}. By
1422 default it has the name
1425 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1439 You use this option (which takes exactly one filename) to give the
1440 object file a different name.
1442 Whatever the object file is called, @code{@value{AS}} overwrites any
1443 existing file of the same name.
1446 @section Join Data and Text Sections: @code{-R}
1449 @cindex data and text sections, joining
1450 @cindex text and data sections, joining
1451 @cindex joining text and data sections
1452 @cindex merging text and data sections
1453 @code{-R} tells @code{@value{AS}} to write the object file as if all
1454 data-section data lives in the text section. This is only done at
1455 the very last moment: your binary data are the same, but data
1456 section parts are relocated differently. The data section part of
1457 your object file is zero bytes long because all its bytes are
1458 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1460 When you specify @code{-R} it would be possible to generate shorter
1461 address displacements (because we do not have to cross between text and
1462 data section). We refrain from doing this simply for compatibility with
1463 older versions of @code{@value{AS}}. In future, @code{-R} may work this way.
1466 When @code{@value{AS}} is configured for COFF output,
1467 this option is only useful if you use sections named @samp{.text} and
1472 @code{-R} is not supported for any of the HPPA targets. Using
1473 @code{-R} generates a warning from @code{@value{AS}}.
1477 @section Display Assembly Statistics: @code{--statistics}
1479 @kindex --statistics
1480 @cindex statistics, about assembly
1481 @cindex time, total for assembly
1482 @cindex space used, maximum for assembly
1483 Use @samp{--statistics} to display two statistics about the resources used by
1484 @code{@value{AS}}: the maximum amount of space allocated during the assembly
1485 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1488 @node traditional-format
1489 @section Compatible output: @code{--traditional-format}
1491 @kindex --traditional-format
1492 For some targets, the output of @code{@value{AS}} is different in some ways
1493 from the output of some existing assembler. This switch requests
1494 @code{@value{AS}} to use the traditional format instead.
1496 For example, it disables the exception frame optimizations which
1497 @code{@value{AS}} normally does by default on @code{@value{GCC}} output.
1500 @section Announce Version: @code{-v}
1504 @cindex assembler version
1505 @cindex version of assembler
1506 You can find out what version of as is running by including the
1507 option @samp{-v} (which you can also spell as @samp{-version}) on the
1511 @section Control Warnings: @code{-W}, @code{--warn}, @code{--no-warn}, @code{--fatal-warnings}
1513 @code{@value{AS}} should never give a warning or error message when
1514 assembling compiler output. But programs written by people often
1515 cause @code{@value{AS}} to give a warning that a particular assumption was
1516 made. All such warnings are directed to the standard error file.
1519 @kindex @samp{--no-warn}
1520 @cindex suppressing warnings
1521 @cindex warnings, suppressing
1522 If you use the @code{-W} and @code{--no-warn} options, no warnings are issued.
1523 This only affects the warning messages: it does not change any particular of
1524 how @code{@value{AS}} assembles your file. Errors, which stop the assembly,
1527 @kindex @samp{--fatal-warnings}
1528 @cindex errors, caused by warnings
1529 @cindex warnings, causing error
1530 If you use the @code{--fatal-warnings} option, @code{@value{AS}} considers
1531 files that generate warnings to be in error.
1533 @kindex @samp{--warn}
1534 @cindex warnings, switching on
1535 You can switch these options off again by specifying @code{--warn}, which
1536 causes warnings to be output as usual.
1539 @section Generate Object File in Spite of Errors: @code{-Z}
1540 @cindex object file, after errors
1541 @cindex errors, continuing after
1542 After an error message, @code{@value{AS}} normally produces no output. If for
1543 some reason you are interested in object file output even after
1544 @code{@value{AS}} gives an error message on your program, use the @samp{-Z}
1545 option. If there are any errors, @code{@value{AS}} continues anyways, and
1546 writes an object file after a final warning message of the form @samp{@var{n}
1547 errors, @var{m} warnings, generating bad object file.}
1552 @cindex machine-independent syntax
1553 @cindex syntax, machine-independent
1554 This chapter describes the machine-independent syntax allowed in a
1555 source file. @code{@value{AS}} syntax is similar to what many other
1556 assemblers use; it is inspired by the BSD 4.2
1561 assembler, except that @code{@value{AS}} does not assemble Vax bit-fields.
1565 * Preprocessing:: Preprocessing
1566 * Whitespace:: Whitespace
1567 * Comments:: Comments
1568 * Symbol Intro:: Symbols
1569 * Statements:: Statements
1570 * Constants:: Constants
1574 @section Preprocessing
1576 @cindex preprocessing
1577 The @code{@value{AS}} internal preprocessor:
1579 @cindex whitespace, removed by preprocessor
1581 adjusts and removes extra whitespace. It leaves one space or tab before
1582 the keywords on a line, and turns any other whitespace on the line into
1585 @cindex comments, removed by preprocessor
1587 removes all comments, replacing them with a single space, or an
1588 appropriate number of newlines.
1590 @cindex constants, converted by preprocessor
1592 converts character constants into the appropriate numeric values.
1595 It does not do macro processing, include file handling, or
1596 anything else you may get from your C compiler's preprocessor. You can
1597 do include file processing with the @code{.include} directive
1598 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1599 to get other ``CPP'' style preprocessing, by giving the input file a
1600 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1601 Output, gcc.info, Using GNU CC}.
1603 Excess whitespace, comments, and character constants
1604 cannot be used in the portions of the input text that are not
1607 @cindex turning preprocessing on and off
1608 @cindex preprocessing, turning on and off
1611 If the first line of an input file is @code{#NO_APP} or if you use the
1612 @samp{-f} option, whitespace and comments are not removed from the input file.
1613 Within an input file, you can ask for whitespace and comment removal in
1614 specific portions of the by putting a line that says @code{#APP} before the
1615 text that may contain whitespace or comments, and putting a line that says
1616 @code{#NO_APP} after this text. This feature is mainly intend to support
1617 @code{asm} statements in compilers whose output is otherwise free of comments
1624 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1625 Whitespace is used to separate symbols, and to make programs neater for
1626 people to read. Unless within character constants
1627 (@pxref{Characters,,Character Constants}), any whitespace means the same
1628 as exactly one space.
1634 There are two ways of rendering comments to @code{@value{AS}}. In both
1635 cases the comment is equivalent to one space.
1637 Anything from @samp{/*} through the next @samp{*/} is a comment.
1638 This means you may not nest these comments.
1642 The only way to include a newline ('\n') in a comment
1643 is to use this sort of comment.
1646 /* This sort of comment does not nest. */
1649 @cindex line comment character
1650 Anything from the @dfn{line comment} character to the next newline
1651 is considered a comment and is ignored. The line comment character is
1653 @samp{;} for the AMD 29K family;
1656 @samp{;} on the ARC;
1659 @samp{@@} on the ARM;
1662 @samp{;} for the H8/300 family;
1665 @samp{!} for the H8/500 family;
1668 @samp{;} for the HPPA;
1671 @samp{#} on the i386 and x86-64;
1674 @samp{#} on the i960;
1677 @samp{;} for picoJava;
1680 @samp{!} for the Hitachi SH;
1683 @samp{!} on the SPARC;
1686 @samp{#} on the m32r;
1689 @samp{|} on the 680x0;
1692 @samp{#} on the 68HC11 and 68HC12;
1695 @samp{#} on the Vax;
1698 @samp{!} for the Z8000;
1701 @samp{#} on the V850;
1703 see @ref{Machine Dependencies}. @refill
1704 @c FIXME What about m88k, i860?
1707 On some machines there are two different line comment characters. One
1708 character only begins a comment if it is the first non-whitespace character on
1709 a line, while the other always begins a comment.
1713 The V850 assembler also supports a double dash as starting a comment that
1714 extends to the end of the line.
1720 @cindex lines starting with @code{#}
1721 @cindex logical line numbers
1722 To be compatible with past assemblers, lines that begin with @samp{#} have a
1723 special interpretation. Following the @samp{#} should be an absolute
1724 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1725 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
1726 new logical file name. The rest of the line, if any, should be whitespace.
1728 If the first non-whitespace characters on the line are not numeric,
1729 the line is ignored. (Just like a comment.)
1732 # This is an ordinary comment.
1733 # 42-6 "new_file_name" # New logical file name
1734 # This is logical line # 36.
1736 This feature is deprecated, and may disappear from future versions
1737 of @code{@value{AS}}.
1742 @cindex characters used in symbols
1743 @ifclear SPECIAL-SYMS
1744 A @dfn{symbol} is one or more characters chosen from the set of all
1745 letters (both upper and lower case), digits and the three characters
1751 A @dfn{symbol} is one or more characters chosen from the set of all
1752 letters (both upper and lower case), digits and the three characters
1753 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
1759 On most machines, you can also use @code{$} in symbol names; exceptions
1760 are noted in @ref{Machine Dependencies}.
1762 No symbol may begin with a digit. Case is significant.
1763 There is no length limit: all characters are significant. Symbols are
1764 delimited by characters not in that set, or by the beginning of a file
1765 (since the source program must end with a newline, the end of a file is
1766 not a possible symbol delimiter). @xref{Symbols}.
1767 @cindex length of symbols
1772 @cindex statements, structure of
1773 @cindex line separator character
1774 @cindex statement separator character
1776 @ifclear abnormal-separator
1777 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
1778 semicolon (@samp{;}). The newline or semicolon is considered part of
1779 the preceding statement. Newlines and semicolons within character
1780 constants are an exception: they do not end statements.
1782 @ifset abnormal-separator
1784 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
1785 sign (@samp{@@}). The newline or at sign is considered part of the
1786 preceding statement. Newlines and at signs within character constants
1787 are an exception: they do not end statements.
1790 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
1791 point (@samp{!}). The newline or exclamation point is considered part of the
1792 preceding statement. Newlines and exclamation points within character
1793 constants are an exception: they do not end statements.
1796 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
1797 H8/300) a dollar sign (@samp{$}); or (for the
1800 (@samp{;}). The newline or separator character is considered part of
1801 the preceding statement. Newlines and separators within character
1802 constants are an exception: they do not end statements.
1807 A @dfn{statement} ends at a newline character (@samp{\n}) or line
1808 separator character. (The line separator is usually @samp{;}, unless
1809 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
1810 newline or separator character is considered part of the preceding
1811 statement. Newlines and separators within character constants are an
1812 exception: they do not end statements.
1815 @cindex newline, required at file end
1816 @cindex EOF, newline must precede
1817 It is an error to end any statement with end-of-file: the last
1818 character of any input file should be a newline.@refill
1820 An empty statement is allowed, and may include whitespace. It is ignored.
1822 @cindex instructions and directives
1823 @cindex directives and instructions
1824 @c "key symbol" is not used elsewhere in the document; seems pedantic to
1825 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
1827 A statement begins with zero or more labels, optionally followed by a
1828 key symbol which determines what kind of statement it is. The key
1829 symbol determines the syntax of the rest of the statement. If the
1830 symbol begins with a dot @samp{.} then the statement is an assembler
1831 directive: typically valid for any computer. If the symbol begins with
1832 a letter the statement is an assembly language @dfn{instruction}: it
1833 assembles into a machine language instruction.
1835 Different versions of @code{@value{AS}} for different computers
1836 recognize different instructions. In fact, the same symbol may
1837 represent a different instruction in a different computer's assembly
1841 @cindex @code{:} (label)
1842 @cindex label (@code{:})
1843 A label is a symbol immediately followed by a colon (@code{:}).
1844 Whitespace before a label or after a colon is permitted, but you may not
1845 have whitespace between a label's symbol and its colon. @xref{Labels}.
1848 For HPPA targets, labels need not be immediately followed by a colon, but
1849 the definition of a label must begin in column zero. This also implies that
1850 only one label may be defined on each line.
1854 label: .directive followed by something
1855 another_label: # This is an empty statement.
1856 instruction operand_1, operand_2, @dots{}
1863 A constant is a number, written so that its value is known by
1864 inspection, without knowing any context. Like this:
1867 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
1868 .ascii "Ring the bell\7" # A string constant.
1869 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
1870 .float 0f-314159265358979323846264338327\
1871 95028841971.693993751E-40 # - pi, a flonum.
1876 * Characters:: Character Constants
1877 * Numbers:: Number Constants
1881 @subsection Character Constants
1883 @cindex character constants
1884 @cindex constants, character
1885 There are two kinds of character constants. A @dfn{character} stands
1886 for one character in one byte and its value may be used in
1887 numeric expressions. String constants (properly called string
1888 @emph{literals}) are potentially many bytes and their values may not be
1889 used in arithmetic expressions.
1893 * Chars:: Characters
1897 @subsubsection Strings
1899 @cindex string constants
1900 @cindex constants, string
1901 A @dfn{string} is written between double-quotes. It may contain
1902 double-quotes or null characters. The way to get special characters
1903 into a string is to @dfn{escape} these characters: precede them with
1904 a backslash @samp{\} character. For example @samp{\\} represents
1905 one backslash: the first @code{\} is an escape which tells
1906 @code{@value{AS}} to interpret the second character literally as a backslash
1907 (which prevents @code{@value{AS}} from recognizing the second @code{\} as an
1908 escape character). The complete list of escapes follows.
1910 @cindex escape codes, character
1911 @cindex character escape codes
1914 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
1916 @cindex @code{\b} (backspace character)
1917 @cindex backspace (@code{\b})
1919 Mnemonic for backspace; for ASCII this is octal code 010.
1922 @c Mnemonic for EOText; for ASCII this is octal code 004.
1924 @cindex @code{\f} (formfeed character)
1925 @cindex formfeed (@code{\f})
1927 Mnemonic for FormFeed; for ASCII this is octal code 014.
1929 @cindex @code{\n} (newline character)
1930 @cindex newline (@code{\n})
1932 Mnemonic for newline; for ASCII this is octal code 012.
1935 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
1937 @cindex @code{\r} (carriage return character)
1938 @cindex carriage return (@code{\r})
1940 Mnemonic for carriage-Return; for ASCII this is octal code 015.
1943 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
1944 @c other assemblers.
1946 @cindex @code{\t} (tab)
1947 @cindex tab (@code{\t})
1949 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
1952 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
1953 @c @item \x @var{digit} @var{digit} @var{digit}
1954 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
1956 @cindex @code{\@var{ddd}} (octal character code)
1957 @cindex octal character code (@code{\@var{ddd}})
1958 @item \ @var{digit} @var{digit} @var{digit}
1959 An octal character code. The numeric code is 3 octal digits.
1960 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
1961 for example, @code{\008} has the value 010, and @code{\009} the value 011.
1963 @cindex @code{\@var{xd...}} (hex character code)
1964 @cindex hex character code (@code{\@var{xd...}})
1965 @item \@code{x} @var{hex-digits...}
1966 A hex character code. All trailing hex digits are combined. Either upper or
1967 lower case @code{x} works.
1969 @cindex @code{\\} (@samp{\} character)
1970 @cindex backslash (@code{\\})
1972 Represents one @samp{\} character.
1975 @c Represents one @samp{'} (accent acute) character.
1976 @c This is needed in single character literals
1977 @c (@xref{Characters,,Character Constants}.) to represent
1980 @cindex @code{\"} (doublequote character)
1981 @cindex doublequote (@code{\"})
1983 Represents one @samp{"} character. Needed in strings to represent
1984 this character, because an unescaped @samp{"} would end the string.
1986 @item \ @var{anything-else}
1987 Any other character when escaped by @kbd{\} gives a warning, but
1988 assembles as if the @samp{\} was not present. The idea is that if
1989 you used an escape sequence you clearly didn't want the literal
1990 interpretation of the following character. However @code{@value{AS}} has no
1991 other interpretation, so @code{@value{AS}} knows it is giving you the wrong
1992 code and warns you of the fact.
1995 Which characters are escapable, and what those escapes represent,
1996 varies widely among assemblers. The current set is what we think
1997 the BSD 4.2 assembler recognizes, and is a subset of what most C
1998 compilers recognize. If you are in doubt, do not use an escape
2002 @subsubsection Characters
2004 @cindex single character constant
2005 @cindex character, single
2006 @cindex constant, single character
2007 A single character may be written as a single quote immediately
2008 followed by that character. The same escapes apply to characters as
2009 to strings. So if you want to write the character backslash, you
2010 must write @kbd{'\\} where the first @code{\} escapes the second
2011 @code{\}. As you can see, the quote is an acute accent, not a
2012 grave accent. A newline
2014 @ifclear abnormal-separator
2015 (or semicolon @samp{;})
2017 @ifset abnormal-separator
2019 (or at sign @samp{@@})
2022 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2028 immediately following an acute accent is taken as a literal character
2029 and does not count as the end of a statement. The value of a character
2030 constant in a numeric expression is the machine's byte-wide code for
2031 that character. @code{@value{AS}} assumes your character code is ASCII:
2032 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2035 @subsection Number Constants
2037 @cindex constants, number
2038 @cindex number constants
2039 @code{@value{AS}} distinguishes three kinds of numbers according to how they
2040 are stored in the target machine. @emph{Integers} are numbers that
2041 would fit into an @code{int} in the C language. @emph{Bignums} are
2042 integers, but they are stored in more than 32 bits. @emph{Flonums}
2043 are floating point numbers, described below.
2046 * Integers:: Integers
2051 * Bit Fields:: Bit Fields
2057 @subsubsection Integers
2059 @cindex constants, integer
2061 @cindex binary integers
2062 @cindex integers, binary
2063 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2064 the binary digits @samp{01}.
2066 @cindex octal integers
2067 @cindex integers, octal
2068 An octal integer is @samp{0} followed by zero or more of the octal
2069 digits (@samp{01234567}).
2071 @cindex decimal integers
2072 @cindex integers, decimal
2073 A decimal integer starts with a non-zero digit followed by zero or
2074 more digits (@samp{0123456789}).
2076 @cindex hexadecimal integers
2077 @cindex integers, hexadecimal
2078 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2079 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2081 Integers have the usual values. To denote a negative integer, use
2082 the prefix operator @samp{-} discussed under expressions
2083 (@pxref{Prefix Ops,,Prefix Operators}).
2086 @subsubsection Bignums
2089 @cindex constants, bignum
2090 A @dfn{bignum} has the same syntax and semantics as an integer
2091 except that the number (or its negative) takes more than 32 bits to
2092 represent in binary. The distinction is made because in some places
2093 integers are permitted while bignums are not.
2096 @subsubsection Flonums
2098 @cindex floating point numbers
2099 @cindex constants, floating point
2101 @cindex precision, floating point
2102 A @dfn{flonum} represents a floating point number. The translation is
2103 indirect: a decimal floating point number from the text is converted by
2104 @code{@value{AS}} to a generic binary floating point number of more than
2105 sufficient precision. This generic floating point number is converted
2106 to a particular computer's floating point format (or formats) by a
2107 portion of @code{@value{AS}} specialized to that computer.
2109 A flonum is written by writing (in order)
2114 (@samp{0} is optional on the HPPA.)
2118 A letter, to tell @code{@value{AS}} the rest of the number is a flonum.
2120 @kbd{e} is recommended. Case is not important.
2122 @c FIXME: verify if flonum syntax really this vague for most cases
2123 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2124 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2127 On the H8/300, H8/500,
2129 and AMD 29K architectures, the letter must be
2130 one of the letters @samp{DFPRSX} (in upper or lower case).
2132 On the ARC, the letter must be one of the letters @samp{DFRS}
2133 (in upper or lower case).
2135 On the Intel 960 architecture, the letter must be
2136 one of the letters @samp{DFT} (in upper or lower case).
2138 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2142 One of the letters @samp{DFPRSX} (in upper or lower case).
2145 One of the letters @samp{DFRS} (in upper or lower case).
2148 One of the letters @samp{DFPRSX} (in upper or lower case).
2151 The letter @samp{E} (upper case only).
2154 One of the letters @samp{DFT} (in upper or lower case).
2159 An optional sign: either @samp{+} or @samp{-}.
2162 An optional @dfn{integer part}: zero or more decimal digits.
2165 An optional @dfn{fractional part}: @samp{.} followed by zero
2166 or more decimal digits.
2169 An optional exponent, consisting of:
2173 An @samp{E} or @samp{e}.
2174 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2175 @c principle this can perfectly well be different on different targets.
2177 Optional sign: either @samp{+} or @samp{-}.
2179 One or more decimal digits.
2184 At least one of the integer part or the fractional part must be
2185 present. The floating point number has the usual base-10 value.
2187 @code{@value{AS}} does all processing using integers. Flonums are computed
2188 independently of any floating point hardware in the computer running
2193 @c Bit fields are written as a general facility but are also controlled
2194 @c by a conditional-compilation flag---which is as of now (21mar91)
2195 @c turned on only by the i960 config of GAS.
2197 @subsubsection Bit Fields
2200 @cindex constants, bit field
2201 You can also define numeric constants as @dfn{bit fields}.
2202 specify two numbers separated by a colon---
2204 @var{mask}:@var{value}
2207 @code{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2210 The resulting number is then packed
2212 @c this conditional paren in case bit fields turned on elsewhere than 960
2213 (in host-dependent byte order)
2215 into a field whose width depends on which assembler directive has the
2216 bit-field as its argument. Overflow (a result from the bitwise and
2217 requiring more binary digits to represent) is not an error; instead,
2218 more constants are generated, of the specified width, beginning with the
2219 least significant digits.@refill
2221 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2222 @code{.short}, and @code{.word} accept bit-field arguments.
2227 @chapter Sections and Relocation
2232 * Secs Background:: Background
2233 * Ld Sections:: Linker Sections
2234 * As Sections:: Assembler Internal Sections
2235 * Sub-Sections:: Sub-Sections
2239 @node Secs Background
2242 Roughly, a section is a range of addresses, with no gaps; all data
2243 ``in'' those addresses is treated the same for some particular purpose.
2244 For example there may be a ``read only'' section.
2246 @cindex linker, and assembler
2247 @cindex assembler, and linker
2248 The linker @code{@value{LD}} reads many object files (partial programs) and
2249 combines their contents to form a runnable program. When @code{@value{AS}}
2250 emits an object file, the partial program is assumed to start at address 0.
2251 @code{@value{LD}} assigns the final addresses for the partial program, so that
2252 different partial programs do not overlap. This is actually an
2253 oversimplification, but it suffices to explain how @code{@value{AS}} uses
2256 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2257 addresses. These blocks slide to their run-time addresses as rigid
2258 units; their length does not change and neither does the order of bytes
2259 within them. Such a rigid unit is called a @emph{section}. Assigning
2260 run-time addresses to sections is called @dfn{relocation}. It includes
2261 the task of adjusting mentions of object-file addresses so they refer to
2262 the proper run-time addresses.
2264 For the H8/300 and H8/500,
2265 and for the Hitachi SH,
2266 @code{@value{AS}} pads sections if needed to
2267 ensure they end on a word (sixteen bit) boundary.
2270 @cindex standard assembler sections
2271 An object file written by @code{@value{AS}} has at least three sections, any
2272 of which may be empty. These are named @dfn{text}, @dfn{data} and
2277 When it generates COFF output,
2279 @code{@value{AS}} can also generate whatever other named sections you specify
2280 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2281 If you do not use any directives that place output in the @samp{.text}
2282 or @samp{.data} sections, these sections still exist, but are empty.
2287 When @code{@value{AS}} generates SOM or ELF output for the HPPA,
2289 @code{@value{AS}} can also generate whatever other named sections you
2290 specify using the @samp{.space} and @samp{.subspace} directives. See
2291 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2292 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2293 assembler directives.
2296 Additionally, @code{@value{AS}} uses different names for the standard
2297 text, data, and bss sections when generating SOM output. Program text
2298 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2299 BSS into @samp{$BSS$}.
2303 Within the object file, the text section starts at address @code{0}, the
2304 data section follows, and the bss section follows the data section.
2307 When generating either SOM or ELF output files on the HPPA, the text
2308 section starts at address @code{0}, the data section at address
2309 @code{0x4000000}, and the bss section follows the data section.
2312 To let @code{@value{LD}} know which data changes when the sections are
2313 relocated, and how to change that data, @code{@value{AS}} also writes to the
2314 object file details of the relocation needed. To perform relocation
2315 @code{@value{LD}} must know, each time an address in the object
2319 Where in the object file is the beginning of this reference to
2322 How long (in bytes) is this reference?
2324 Which section does the address refer to? What is the numeric value of
2326 (@var{address}) @minus{} (@var{start-address of section})?
2329 Is the reference to an address ``Program-Counter relative''?
2332 @cindex addresses, format of
2333 @cindex section-relative addressing
2334 In fact, every address @code{@value{AS}} ever uses is expressed as
2336 (@var{section}) + (@var{offset into section})
2339 Further, most expressions @code{@value{AS}} computes have this section-relative
2342 (For some object formats, such as SOM for the HPPA, some expressions are
2343 symbol-relative instead.)
2346 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2347 @var{N} into section @var{secname}.''
2349 Apart from text, data and bss sections you need to know about the
2350 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2351 addresses in the absolute section remain unchanged. For example, address
2352 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2353 @code{@value{LD}}. Although the linker never arranges two partial programs'
2354 data sections with overlapping addresses after linking, @emph{by definition}
2355 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2356 part of a program is always the same address when the program is running as
2357 address @code{@{absolute@ 239@}} in any other part of the program.
2359 The idea of sections is extended to the @dfn{undefined} section. Any
2360 address whose section is unknown at assembly time is by definition
2361 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2362 Since numbers are always defined, the only way to generate an undefined
2363 address is to mention an undefined symbol. A reference to a named
2364 common block would be such a symbol: its value is unknown at assembly
2365 time so it has section @emph{undefined}.
2367 By analogy the word @emph{section} is used to describe groups of sections in
2368 the linked program. @code{@value{LD}} puts all partial programs' text
2369 sections in contiguous addresses in the linked program. It is
2370 customary to refer to the @emph{text section} of a program, meaning all
2371 the addresses of all partial programs' text sections. Likewise for
2372 data and bss sections.
2374 Some sections are manipulated by @code{@value{LD}}; others are invented for
2375 use of @code{@value{AS}} and have no meaning except during assembly.
2378 @section Linker Sections
2379 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2384 @cindex named sections
2385 @cindex sections, named
2386 @item named sections
2389 @cindex text section
2390 @cindex data section
2394 These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as
2395 separate but equal sections. Anything you can say of one section is
2398 When the program is running, however, it is
2399 customary for the text section to be unalterable. The
2400 text section is often shared among processes: it contains
2401 instructions, constants and the like. The data section of a running
2402 program is usually alterable: for example, C variables would be stored
2403 in the data section.
2408 This section contains zeroed bytes when your program begins running. It
2409 is used to hold unitialized variables or common storage. The length of
2410 each partial program's bss section is important, but because it starts
2411 out containing zeroed bytes there is no need to store explicit zero
2412 bytes in the object file. The bss section was invented to eliminate
2413 those explicit zeros from object files.
2415 @cindex absolute section
2416 @item absolute section
2417 Address 0 of this section is always ``relocated'' to runtime address 0.
2418 This is useful if you want to refer to an address that @code{@value{LD}} must
2419 not change when relocating. In this sense we speak of absolute
2420 addresses being ``unrelocatable'': they do not change during relocation.
2422 @cindex undefined section
2423 @item undefined section
2424 This ``section'' is a catch-all for address references to objects not in
2425 the preceding sections.
2426 @c FIXME: ref to some other doc on obj-file formats could go here.
2429 @cindex relocation example
2430 An idealized example of three relocatable sections follows.
2432 The example uses the traditional section names @samp{.text} and @samp{.data}.
2434 Memory addresses are on the horizontal axis.
2438 @c END TEXI2ROFF-KILL
2441 partial program # 1: |ttttt|dddd|00|
2448 partial program # 2: |TTT|DDD|000|
2451 +--+---+-----+--+----+---+-----+~~
2452 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2453 +--+---+-----+--+----+---+-----+~~
2455 addresses: 0 @dots{}
2462 \line{\it Partial program \#1: \hfil}
2463 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2464 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2466 \line{\it Partial program \#2: \hfil}
2467 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2468 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2470 \line{\it linked program: \hfil}
2471 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2472 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2473 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2474 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2476 \line{\it addresses: \hfil}
2480 @c END TEXI2ROFF-KILL
2483 @section Assembler Internal Sections
2485 @cindex internal assembler sections
2486 @cindex sections in messages, internal
2487 These sections are meant only for the internal use of @code{@value{AS}}. They
2488 have no meaning at run-time. You do not really need to know about these
2489 sections for most purposes; but they can be mentioned in @code{@value{AS}}
2490 warning messages, so it might be helpful to have an idea of their
2491 meanings to @code{@value{AS}}. These sections are used to permit the
2492 value of every expression in your assembly language program to be a
2493 section-relative address.
2496 @cindex assembler internal logic error
2497 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2498 An internal assembler logic error has been found. This means there is a
2499 bug in the assembler.
2501 @cindex expr (internal section)
2503 The assembler stores complex expression internally as combinations of
2504 symbols. When it needs to represent an expression as a symbol, it puts
2505 it in the expr section.
2507 @c FIXME item transfer[t] vector preload
2508 @c FIXME item transfer[t] vector postload
2509 @c FIXME item register
2513 @section Sub-Sections
2515 @cindex numbered subsections
2516 @cindex grouping data
2522 fall into two sections: text and data.
2524 You may have separate groups of
2526 data in named sections
2530 data in named sections
2536 that you want to end up near to each other in the object file, even though they
2537 are not contiguous in the assembler source. @code{@value{AS}} allows you to
2538 use @dfn{subsections} for this purpose. Within each section, there can be
2539 numbered subsections with values from 0 to 8192. Objects assembled into the
2540 same subsection go into the object file together with other objects in the same
2541 subsection. For example, a compiler might want to store constants in the text
2542 section, but might not want to have them interspersed with the program being
2543 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2544 section of code being output, and a @samp{.text 1} before each group of
2545 constants being output.
2547 Subsections are optional. If you do not use subsections, everything
2548 goes in subsection number zero.
2551 Each subsection is zero-padded up to a multiple of four bytes.
2552 (Subsections may be padded a different amount on different flavors
2553 of @code{@value{AS}}.)
2557 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2558 boundary (two bytes).
2559 The same is true on the Hitachi SH.
2562 @c FIXME section padding (alignment)?
2563 @c Rich Pixley says padding here depends on target obj code format; that
2564 @c doesn't seem particularly useful to say without further elaboration,
2565 @c so for now I say nothing about it. If this is a generic BFD issue,
2566 @c these paragraphs might need to vanish from this manual, and be
2567 @c discussed in BFD chapter of binutils (or some such).
2570 On the AMD 29K family, no particular padding is added to section or
2571 subsection sizes; @value{AS} forces no alignment on this platform.
2575 Subsections appear in your object file in numeric order, lowest numbered
2576 to highest. (All this to be compatible with other people's assemblers.)
2577 The object file contains no representation of subsections; @code{@value{LD}} and
2578 other programs that manipulate object files see no trace of them.
2579 They just see all your text subsections as a text section, and all your
2580 data subsections as a data section.
2582 To specify which subsection you want subsequent statements assembled
2583 into, use a numeric argument to specify it, in a @samp{.text
2584 @var{expression}} or a @samp{.data @var{expression}} statement.
2587 When generating COFF output, you
2592 can also use an extra subsection
2593 argument with arbitrary named sections: @samp{.section @var{name},
2596 @var{Expression} should be an absolute expression.
2597 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2598 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2599 begins in @code{text 0}. For instance:
2601 .text 0 # The default subsection is text 0 anyway.
2602 .ascii "This lives in the first text subsection. *"
2604 .ascii "But this lives in the second text subsection."
2606 .ascii "This lives in the data section,"
2607 .ascii "in the first data subsection."
2609 .ascii "This lives in the first text section,"
2610 .ascii "immediately following the asterisk (*)."
2613 Each section has a @dfn{location counter} incremented by one for every byte
2614 assembled into that section. Because subsections are merely a convenience
2615 restricted to @code{@value{AS}} there is no concept of a subsection location
2616 counter. There is no way to directly manipulate a location counter---but the
2617 @code{.align} directive changes it, and any label definition captures its
2618 current value. The location counter of the section where statements are being
2619 assembled is said to be the @dfn{active} location counter.
2622 @section bss Section
2625 @cindex common variable storage
2626 The bss section is used for local common variable storage.
2627 You may allocate address space in the bss section, but you may
2628 not dictate data to load into it before your program executes. When
2629 your program starts running, all the contents of the bss
2630 section are zeroed bytes.
2632 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2633 @ref{Lcomm,,@code{.lcomm}}.
2635 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2636 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2639 When assembling for a target which supports multiple sections, such as ELF or
2640 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2641 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2642 section. Typically the section will only contain symbol definitions and
2643 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2650 Symbols are a central concept: the programmer uses symbols to name
2651 things, the linker uses symbols to link, and the debugger uses symbols
2655 @cindex debuggers, and symbol order
2656 @emph{Warning:} @code{@value{AS}} does not place symbols in the object file in
2657 the same order they were declared. This may break some debuggers.
2662 * Setting Symbols:: Giving Symbols Other Values
2663 * Symbol Names:: Symbol Names
2664 * Dot:: The Special Dot Symbol
2665 * Symbol Attributes:: Symbol Attributes
2672 A @dfn{label} is written as a symbol immediately followed by a colon
2673 @samp{:}. The symbol then represents the current value of the
2674 active location counter, and is, for example, a suitable instruction
2675 operand. You are warned if you use the same symbol to represent two
2676 different locations: the first definition overrides any other
2680 On the HPPA, the usual form for a label need not be immediately followed by a
2681 colon, but instead must start in column zero. Only one label may be defined on
2682 a single line. To work around this, the HPPA version of @code{@value{AS}} also
2683 provides a special directive @code{.label} for defining labels more flexibly.
2686 @node Setting Symbols
2687 @section Giving Symbols Other Values
2689 @cindex assigning values to symbols
2690 @cindex symbol values, assigning
2691 A symbol can be given an arbitrary value by writing a symbol, followed
2692 by an equals sign @samp{=}, followed by an expression
2693 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2694 directive. @xref{Set,,@code{.set}}.
2697 @section Symbol Names
2699 @cindex symbol names
2700 @cindex names, symbol
2701 @ifclear SPECIAL-SYMS
2702 Symbol names begin with a letter or with one of @samp{._}. On most
2703 machines, you can also use @code{$} in symbol names; exceptions are
2704 noted in @ref{Machine Dependencies}. That character may be followed by any
2705 string of digits, letters, dollar signs (unless otherwise noted in
2706 @ref{Machine Dependencies}), and underscores.
2709 For the AMD 29K family, @samp{?} is also allowed in the
2710 body of a symbol name, though not at its beginning.
2715 Symbol names begin with a letter or with one of @samp{._}. On the
2717 H8/500, you can also use @code{$} in symbol names. That character may
2718 be followed by any string of digits, letters, dollar signs (save on the
2719 H8/300), and underscores.
2723 Case of letters is significant: @code{foo} is a different symbol name
2726 Each symbol has exactly one name. Each name in an assembly language program
2727 refers to exactly one symbol. You may use that symbol name any number of times
2730 @subheading Local Symbol Names
2732 @cindex local symbol names
2733 @cindex symbol names, local
2734 @cindex temporary symbol names
2735 @cindex symbol names, temporary
2736 Local symbols help compilers and programmers use names temporarily.
2737 There are ten local symbol names, which are re-used throughout the
2738 program. You may refer to them using the names @samp{0} @samp{1}
2739 @dots{} @samp{9}. To define a local symbol, write a label of the form
2740 @samp{@b{N}:} (where @b{N} represents any digit). To refer to the most
2741 recent previous definition of that symbol write @samp{@b{N}b}, using the
2742 same digit as when you defined the label. To refer to the next
2743 definition of a local label, write @samp{@b{N}f}---where @b{N} gives you
2744 a choice of 10 forward references. The @samp{b} stands for
2745 ``backwards'' and the @samp{f} stands for ``forwards''.
2747 Local symbols are not emitted by the current @sc{gnu} C compiler.
2749 There is no restriction on how you can use these labels, but
2750 remember that at any point in the assembly you can refer to at most
2751 10 prior local labels and to at most 10 forward local labels.
2753 Local symbol names are only a notation device. They are immediately
2754 transformed into more conventional symbol names before the assembler
2755 uses them. The symbol names stored in the symbol table, appearing in
2756 error messages and optionally emitted to the object file have these
2761 All local labels begin with @samp{L}. Normally both @code{@value{AS}} and
2762 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
2763 used for symbols you are never intended to see. If you use the
2764 @samp{-L} option then @code{@value{AS}} retains these symbols in the
2765 object file. If you also instruct @code{@value{LD}} to retain these symbols,
2766 you may use them in debugging.
2769 If the label is written @samp{0:} then the digit is @samp{0}.
2770 If the label is written @samp{1:} then the digit is @samp{1}.
2771 And so on up through @samp{9:}.
2774 This unusual character is included so you do not accidentally invent
2775 a symbol of the same name. The character has ASCII value
2778 @item @emph{ordinal number}
2779 This is a serial number to keep the labels distinct. The first
2780 @samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the
2781 number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:}
2785 For instance, the first @code{1:} is named @code{L1@kbd{C-A}1}, the 44th
2786 @code{3:} is named @code{L3@kbd{C-A}44}.
2789 @section The Special Dot Symbol
2791 @cindex dot (symbol)
2792 @cindex @code{.} (symbol)
2793 @cindex current address
2794 @cindex location counter
2795 The special symbol @samp{.} refers to the current address that
2796 @code{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
2797 .long .} defines @code{melvin} to contain its own address.
2798 Assigning a value to @code{.} is treated the same as a @code{.org}
2799 directive. Thus, the expression @samp{.=.+4} is the same as saying
2800 @ifclear no-space-dir
2809 @node Symbol Attributes
2810 @section Symbol Attributes
2812 @cindex symbol attributes
2813 @cindex attributes, symbol
2814 Every symbol has, as well as its name, the attributes ``Value'' and
2815 ``Type''. Depending on output format, symbols can also have auxiliary
2818 The detailed definitions are in @file{a.out.h}.
2821 If you use a symbol without defining it, @code{@value{AS}} assumes zero for
2822 all these attributes, and probably won't warn you. This makes the
2823 symbol an externally defined symbol, which is generally what you
2827 * Symbol Value:: Value
2828 * Symbol Type:: Type
2831 * a.out Symbols:: Symbol Attributes: @code{a.out}
2835 * a.out Symbols:: Symbol Attributes: @code{a.out}
2838 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
2843 * COFF Symbols:: Symbol Attributes for COFF
2846 * SOM Symbols:: Symbol Attributes for SOM
2853 @cindex value of a symbol
2854 @cindex symbol value
2855 The value of a symbol is (usually) 32 bits. For a symbol which labels a
2856 location in the text, data, bss or absolute sections the value is the
2857 number of addresses from the start of that section to the label.
2858 Naturally for text, data and bss sections the value of a symbol changes
2859 as @code{@value{LD}} changes section base addresses during linking. Absolute
2860 symbols' values do not change during linking: that is why they are
2863 The value of an undefined symbol is treated in a special way. If it is
2864 0 then the symbol is not defined in this assembler source file, and
2865 @code{@value{LD}} tries to determine its value from other files linked into the
2866 same program. You make this kind of symbol simply by mentioning a symbol
2867 name without defining it. A non-zero value represents a @code{.comm}
2868 common declaration. The value is how much common storage to reserve, in
2869 bytes (addresses). The symbol refers to the first address of the
2875 @cindex type of a symbol
2877 The type attribute of a symbol contains relocation (section)
2878 information, any flag settings indicating that a symbol is external, and
2879 (optionally), other information for linkers and debuggers. The exact
2880 format depends on the object-code output format in use.
2885 @c The following avoids a "widow" subsection title. @group would be
2886 @c better if it were available outside examples.
2889 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
2891 @cindex @code{b.out} symbol attributes
2892 @cindex symbol attributes, @code{b.out}
2893 These symbol attributes appear only when @code{@value{AS}} is configured for
2894 one of the Berkeley-descended object output formats---@code{a.out} or
2900 @subsection Symbol Attributes: @code{a.out}
2902 @cindex @code{a.out} symbol attributes
2903 @cindex symbol attributes, @code{a.out}
2909 @subsection Symbol Attributes: @code{a.out}
2911 @cindex @code{a.out} symbol attributes
2912 @cindex symbol attributes, @code{a.out}
2916 * Symbol Desc:: Descriptor
2917 * Symbol Other:: Other
2921 @subsubsection Descriptor
2923 @cindex descriptor, of @code{a.out} symbol
2924 This is an arbitrary 16-bit value. You may establish a symbol's
2925 descriptor value by using a @code{.desc} statement
2926 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
2930 @subsubsection Other
2932 @cindex other attribute, of @code{a.out} symbol
2933 This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}.
2938 @subsection Symbol Attributes for COFF
2940 @cindex COFF symbol attributes
2941 @cindex symbol attributes, COFF
2943 The COFF format supports a multitude of auxiliary symbol attributes;
2944 like the primary symbol attributes, they are set between @code{.def} and
2945 @code{.endef} directives.
2947 @subsubsection Primary Attributes
2949 @cindex primary attributes, COFF symbols
2950 The symbol name is set with @code{.def}; the value and type,
2951 respectively, with @code{.val} and @code{.type}.
2953 @subsubsection Auxiliary Attributes
2955 @cindex auxiliary attributes, COFF symbols
2956 The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
2957 @code{.size}, and @code{.tag} can generate auxiliary symbol table
2958 information for COFF.
2963 @subsection Symbol Attributes for SOM
2965 @cindex SOM symbol attributes
2966 @cindex symbol attributes, SOM
2968 The SOM format for the HPPA supports a multitude of symbol attributes set with
2969 the @code{.EXPORT} and @code{.IMPORT} directives.
2971 The attributes are described in @cite{HP9000 Series 800 Assembly
2972 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
2973 @code{EXPORT} assembler directive documentation.
2977 @chapter Expressions
2981 @cindex numeric values
2982 An @dfn{expression} specifies an address or numeric value.
2983 Whitespace may precede and/or follow an expression.
2985 The result of an expression must be an absolute number, or else an offset into
2986 a particular section. If an expression is not absolute, and there is not
2987 enough information when @code{@value{AS}} sees the expression to know its
2988 section, a second pass over the source program might be necessary to interpret
2989 the expression---but the second pass is currently not implemented.
2990 @code{@value{AS}} aborts with an error message in this situation.
2993 * Empty Exprs:: Empty Expressions
2994 * Integer Exprs:: Integer Expressions
2998 @section Empty Expressions
3000 @cindex empty expressions
3001 @cindex expressions, empty
3002 An empty expression has no value: it is just whitespace or null.
3003 Wherever an absolute expression is required, you may omit the
3004 expression, and @code{@value{AS}} assumes a value of (absolute) 0. This
3005 is compatible with other assemblers.
3008 @section Integer Expressions
3010 @cindex integer expressions
3011 @cindex expressions, integer
3012 An @dfn{integer expression} is one or more @emph{arguments} delimited
3013 by @emph{operators}.
3016 * Arguments:: Arguments
3017 * Operators:: Operators
3018 * Prefix Ops:: Prefix Operators
3019 * Infix Ops:: Infix Operators
3023 @subsection Arguments
3025 @cindex expression arguments
3026 @cindex arguments in expressions
3027 @cindex operands in expressions
3028 @cindex arithmetic operands
3029 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3030 contexts arguments are sometimes called ``arithmetic operands''. In
3031 this manual, to avoid confusing them with the ``instruction operands'' of
3032 the machine language, we use the term ``argument'' to refer to parts of
3033 expressions only, reserving the word ``operand'' to refer only to machine
3034 instruction operands.
3036 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3037 @var{section} is one of text, data, bss, absolute,
3038 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3041 Numbers are usually integers.
3043 A number can be a flonum or bignum. In this case, you are warned
3044 that only the low order 32 bits are used, and @code{@value{AS}} pretends
3045 these 32 bits are an integer. You may write integer-manipulating
3046 instructions that act on exotic constants, compatible with other
3049 @cindex subexpressions
3050 Subexpressions are a left parenthesis @samp{(} followed by an integer
3051 expression, followed by a right parenthesis @samp{)}; or a prefix
3052 operator followed by an argument.
3055 @subsection Operators
3057 @cindex operators, in expressions
3058 @cindex arithmetic functions
3059 @cindex functions, in expressions
3060 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3061 operators are followed by an argument. Infix operators appear
3062 between their arguments. Operators may be preceded and/or followed by
3066 @subsection Prefix Operator
3068 @cindex prefix operators
3069 @code{@value{AS}} has the following @dfn{prefix operators}. They each take
3070 one argument, which must be absolute.
3072 @c the tex/end tex stuff surrounding this small table is meant to make
3073 @c it align, on the printed page, with the similar table in the next
3074 @c section (which is inside an enumerate).
3076 \global\advance\leftskip by \itemindent
3081 @dfn{Negation}. Two's complement negation.
3083 @dfn{Complementation}. Bitwise not.
3087 \global\advance\leftskip by -\itemindent
3091 @subsection Infix Operators
3093 @cindex infix operators
3094 @cindex operators, permitted arguments
3095 @dfn{Infix operators} take two arguments, one on either side. Operators
3096 have precedence, but operations with equal precedence are performed left
3097 to right. Apart from @code{+} or @code{-}, both arguments must be
3098 absolute, and the result is absolute.
3101 @cindex operator precedence
3102 @cindex precedence of operators
3109 @dfn{Multiplication}.
3112 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3119 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3123 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3127 Intermediate precedence
3132 @dfn{Bitwise Inclusive Or}.
3138 @dfn{Bitwise Exclusive Or}.
3141 @dfn{Bitwise Or Not}.
3148 @cindex addition, permitted arguments
3149 @cindex plus, permitted arguments
3150 @cindex arguments for addition
3152 @dfn{Addition}. If either argument is absolute, the result has the section of
3153 the other argument. You may not add together arguments from different
3156 @cindex subtraction, permitted arguments
3157 @cindex minus, permitted arguments
3158 @cindex arguments for subtraction
3160 @dfn{Subtraction}. If the right argument is absolute, the
3161 result has the section of the left argument.
3162 If both arguments are in the same section, the result is absolute.
3163 You may not subtract arguments from different sections.
3164 @c FIXME is there still something useful to say about undefined - undefined ?
3168 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3169 address; you can only have a defined section in one of the two arguments.
3172 @chapter Assembler Directives
3174 @cindex directives, machine independent
3175 @cindex pseudo-ops, machine independent
3176 @cindex machine independent directives
3177 All assembler directives have names that begin with a period (@samp{.}).
3178 The rest of the name is letters, usually in lower case.
3180 This chapter discusses directives that are available regardless of the
3181 target machine configuration for the @sc{gnu} assembler.
3183 Some machine configurations provide additional directives.
3184 @xref{Machine Dependencies}.
3187 @ifset machine-directives
3188 @xref{Machine Dependencies} for additional directives.
3193 * Abort:: @code{.abort}
3195 * ABORT:: @code{.ABORT}
3198 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3199 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3200 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3201 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3202 * Byte:: @code{.byte @var{expressions}}
3203 * Comm:: @code{.comm @var{symbol} , @var{length} }
3204 * Data:: @code{.data @var{subsection}}
3206 * Def:: @code{.def @var{name}}
3209 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3215 * Double:: @code{.double @var{flonums}}
3216 * Eject:: @code{.eject}
3217 * Else:: @code{.else}
3218 * Elseif:: @code{.elseif}
3221 * Endef:: @code{.endef}
3224 * Endfunc:: @code{.endfunc}
3225 * Endif:: @code{.endif}
3226 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3227 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3229 * Exitm:: @code{.exitm}
3230 * Extern:: @code{.extern}
3231 * Fail:: @code{.fail}
3232 @ifclear no-file-dir
3233 * File:: @code{.file @var{string}}
3236 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3237 * Float:: @code{.float @var{flonums}}
3238 * Func:: @code{.func}
3239 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3241 * Hidden:: @code{.hidden @var{names}}
3244 * hword:: @code{.hword @var{expressions}}
3245 * Ident:: @code{.ident}
3246 * If:: @code{.if @var{absolute expression}}
3247 * Include:: @code{.include "@var{file}"}
3248 * Int:: @code{.int @var{expressions}}
3250 * Internal:: @code{.internal @var{names}}
3253 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3254 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3255 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3256 * Lflags:: @code{.lflags}
3257 @ifclear no-line-dir
3258 * Line:: @code{.line @var{line-number}}
3261 * Ln:: @code{.ln @var{line-number}}
3262 * Linkonce:: @code{.linkonce [@var{type}]}
3263 * List:: @code{.list}
3264 * Long:: @code{.long @var{expressions}}
3266 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3269 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3270 * MRI:: @code{.mri @var{val}}
3271 * Nolist:: @code{.nolist}
3272 * Octa:: @code{.octa @var{bignums}}
3273 * Org:: @code{.org @var{new-lc} , @var{fill}}
3274 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3276 * PopSection:: @code{.popsection}
3277 * Previous:: @code{.previous}
3280 * Print:: @code{.print @var{string}}
3282 * Protected:: @code{.protected @var{names}}
3285 * Psize:: @code{.psize @var{lines}, @var{columns}}
3286 * Purgem:: @code{.purgem @var{name}}
3288 * PushSection:: @code{.pushsection @var{name}}
3291 * Quad:: @code{.quad @var{bignums}}
3292 * Rept:: @code{.rept @var{count}}
3293 * Sbttl:: @code{.sbttl "@var{subheading}"}
3295 * Scl:: @code{.scl @var{class}}
3296 * Section:: @code{.section @var{name}, @var{subsection}}
3299 * Set:: @code{.set @var{symbol}, @var{expression}}
3300 * Short:: @code{.short @var{expressions}}
3301 * Single:: @code{.single @var{flonums}}
3302 * Size:: @code{.size [@var{name} , @var{expression}]}
3303 * Skip:: @code{.skip @var{size} , @var{fill}}
3304 * Sleb128:: @code{.sleb128 @var{expressions}}
3305 * Space:: @code{.space @var{size} , @var{fill}}
3307 * Stab:: @code{.stabd, .stabn, .stabs}
3310 * String:: @code{.string "@var{str}"}
3311 * Struct:: @code{.struct @var{expression}}
3313 * SubSection:: @code{.subsection}
3314 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3318 * Tag:: @code{.tag @var{structname}}
3321 * Text:: @code{.text @var{subsection}}
3322 * Title:: @code{.title "@var{heading}"}
3323 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3324 * Uleb128:: @code{.uleb128 @var{expressions}}
3326 * Val:: @code{.val @var{addr}}
3330 * Version:: @code{.version "@var{string}"}
3331 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3332 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3333 * Weak:: @code{.weak @var{names}}
3336 * Word:: @code{.word @var{expressions}}
3337 * Deprecated:: Deprecated Directives
3341 @section @code{.abort}
3343 @cindex @code{abort} directive
3344 @cindex stopping the assembly
3345 This directive stops the assembly immediately. It is for
3346 compatibility with other assemblers. The original idea was that the
3347 assembly language source would be piped into the assembler. If the sender
3348 of the source quit, it could use this directive tells @code{@value{AS}} to
3349 quit also. One day @code{.abort} will not be supported.
3353 @section @code{.ABORT}
3355 @cindex @code{ABORT} directive
3356 When producing COFF output, @code{@value{AS}} accepts this directive as a
3357 synonym for @samp{.abort}.
3360 When producing @code{b.out} output, @code{@value{AS}} accepts this directive,
3366 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3368 @cindex padding the location counter
3369 @cindex @code{align} directive
3370 Pad the location counter (in the current subsection) to a particular storage
3371 boundary. The first expression (which must be absolute) is the alignment
3372 required, as described below.
3374 The second expression (also absolute) gives the fill value to be stored in the
3375 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3376 padding bytes are normally zero. However, on some systems, if the section is
3377 marked as containing code and the fill value is omitted, the space is filled
3378 with no-op instructions.
3380 The third expression is also absolute, and is also optional. If it is present,
3381 it is the maximum number of bytes that should be skipped by this alignment
3382 directive. If doing the alignment would require skipping more bytes than the
3383 specified maximum, then the alignment is not done at all. You can omit the
3384 fill value (the second argument) entirely by simply using two commas after the
3385 required alignment; this can be useful if you want the alignment to be filled
3386 with no-op instructions when appropriate.
3388 The way the required alignment is specified varies from system to system.
3389 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3391 the first expression is the
3392 alignment request in bytes. For example @samp{.align 8} advances
3393 the location counter until it is a multiple of 8. If the location counter
3394 is already a multiple of 8, no change is needed.
3396 For other systems, including the i386 using a.out format, and the arm and
3397 strongarm, it is the
3398 number of low-order zero bits the location counter must have after
3399 advancement. For example @samp{.align 3} advances the location
3400 counter until it a multiple of 8. If the location counter is already a
3401 multiple of 8, no change is needed.
3403 This inconsistency is due to the different behaviors of the various
3404 native assemblers for these systems which GAS must emulate.
3405 GAS also provides @code{.balign} and @code{.p2align} directives,
3406 described later, which have a consistent behavior across all
3407 architectures (but are specific to GAS).
3410 @section @code{.ascii "@var{string}"}@dots{}
3412 @cindex @code{ascii} directive
3413 @cindex string literals
3414 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3415 separated by commas. It assembles each string (with no automatic
3416 trailing zero byte) into consecutive addresses.
3419 @section @code{.asciz "@var{string}"}@dots{}
3421 @cindex @code{asciz} directive
3422 @cindex zero-terminated strings
3423 @cindex null-terminated strings
3424 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3425 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3428 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3430 @cindex padding the location counter given number of bytes
3431 @cindex @code{balign} directive
3432 Pad the location counter (in the current subsection) to a particular
3433 storage boundary. The first expression (which must be absolute) is the
3434 alignment request in bytes. For example @samp{.balign 8} advances
3435 the location counter until it is a multiple of 8. If the location counter
3436 is already a multiple of 8, no change is needed.
3438 The second expression (also absolute) gives the fill value to be stored in the
3439 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3440 padding bytes are normally zero. However, on some systems, if the section is
3441 marked as containing code and the fill value is omitted, the space is filled
3442 with no-op instructions.
3444 The third expression is also absolute, and is also optional. If it is present,
3445 it is the maximum number of bytes that should be skipped by this alignment
3446 directive. If doing the alignment would require skipping more bytes than the
3447 specified maximum, then the alignment is not done at all. You can omit the
3448 fill value (the second argument) entirely by simply using two commas after the
3449 required alignment; this can be useful if you want the alignment to be filled
3450 with no-op instructions when appropriate.
3452 @cindex @code{balignw} directive
3453 @cindex @code{balignl} directive
3454 The @code{.balignw} and @code{.balignl} directives are variants of the
3455 @code{.balign} directive. The @code{.balignw} directive treats the fill
3456 pattern as a two byte word value. The @code{.balignl} directives treats the
3457 fill pattern as a four byte longword value. For example, @code{.balignw
3458 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3459 filled in with the value 0x368d (the exact placement of the bytes depends upon
3460 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3464 @section @code{.byte @var{expressions}}
3466 @cindex @code{byte} directive
3467 @cindex integers, one byte
3468 @code{.byte} expects zero or more expressions, separated by commas.
3469 Each expression is assembled into the next byte.
3472 @section @code{.comm @var{symbol} , @var{length} }
3474 @cindex @code{comm} directive
3475 @cindex symbol, common
3476 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3477 common symbol in one object file may be merged with a defined or common symbol
3478 of the same name in another object file. If @code{@value{LD}} does not see a
3479 definition for the symbol--just one or more common symbols--then it will
3480 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3481 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3482 the same name, and they do not all have the same size, it will allocate space
3483 using the largest size.
3486 When using ELF, the @code{.comm} directive takes an optional third argument.
3487 This is the desired alignment of the symbol, specified as a byte boundary (for
3488 example, an alignment of 16 means that the least significant 4 bits of the
3489 address should be zero). The alignment must be an absolute expression, and it
3490 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3491 for the common symbol, it will use the alignment when placing the symbol. If
3492 no alignment is specified, @code{@value{AS}} will set the alignment to the
3493 largest power of two less than or equal to the size of the symbol, up to a
3498 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3499 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3503 @section @code{.data @var{subsection}}
3505 @cindex @code{data} directive
3506 @code{.data} tells @code{@value{AS}} to assemble the following statements onto the
3507 end of the data subsection numbered @var{subsection} (which is an
3508 absolute expression). If @var{subsection} is omitted, it defaults
3513 @section @code{.def @var{name}}
3515 @cindex @code{def} directive
3516 @cindex COFF symbols, debugging
3517 @cindex debugging COFF symbols
3518 Begin defining debugging information for a symbol @var{name}; the
3519 definition extends until the @code{.endef} directive is encountered.
3522 This directive is only observed when @code{@value{AS}} is configured for COFF
3523 format output; when producing @code{b.out}, @samp{.def} is recognized,
3530 @section @code{.desc @var{symbol}, @var{abs-expression}}
3532 @cindex @code{desc} directive
3533 @cindex COFF symbol descriptor
3534 @cindex symbol descriptor, COFF
3535 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3536 to the low 16 bits of an absolute expression.
3539 The @samp{.desc} directive is not available when @code{@value{AS}} is
3540 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3541 object format. For the sake of compatibility, @code{@value{AS}} accepts
3542 it, but produces no output, when configured for COFF.
3548 @section @code{.dim}
3550 @cindex @code{dim} directive
3551 @cindex COFF auxiliary symbol information
3552 @cindex auxiliary symbol information, COFF
3553 This directive is generated by compilers to include auxiliary debugging
3554 information in the symbol table. It is only permitted inside
3555 @code{.def}/@code{.endef} pairs.
3558 @samp{.dim} is only meaningful when generating COFF format output; when
3559 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
3565 @section @code{.double @var{flonums}}
3567 @cindex @code{double} directive
3568 @cindex floating point numbers (double)
3569 @code{.double} expects zero or more flonums, separated by commas. It
3570 assembles floating point numbers.
3572 The exact kind of floating point numbers emitted depends on how
3573 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
3577 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3578 in @sc{ieee} format.
3583 @section @code{.eject}
3585 @cindex @code{eject} directive
3586 @cindex new page, in listings
3587 @cindex page, in listings
3588 @cindex listing control: new page
3589 Force a page break at this point, when generating assembly listings.
3592 @section @code{.else}
3594 @cindex @code{else} directive
3595 @code{.else} is part of the @code{@value{AS}} support for conditional
3596 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3597 of code to be assembled if the condition for the preceding @code{.if}
3601 @section @code{.elseif}
3603 @cindex @code{elseif} directive
3604 @code{.elseif} is part of the @code{@value{AS}} support for conditional
3605 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3606 @code{.if} block that would otherwise fill the entire @code{.else} section.
3609 @section @code{.end}
3611 @cindex @code{end} directive
3612 @code{.end} marks the end of the assembly file. @code{@value{AS}} does not
3613 process anything in the file past the @code{.end} directive.
3617 @section @code{.endef}
3619 @cindex @code{endef} directive
3620 This directive flags the end of a symbol definition begun with
3624 @samp{.endef} is only meaningful when generating COFF format output; if
3625 @code{@value{AS}} is configured to generate @code{b.out}, it accepts this
3626 directive but ignores it.
3631 @section @code{.endfunc}
3632 @cindex @code{endfunc} directive
3633 @code{.endfunc} marks the end of a function specified with @code{.func}.
3636 @section @code{.endif}
3638 @cindex @code{endif} directive
3639 @code{.endif} is part of the @code{@value{AS}} support for conditional assembly;
3640 it marks the end of a block of code that is only assembled
3641 conditionally. @xref{If,,@code{.if}}.
3644 @section @code{.equ @var{symbol}, @var{expression}}
3646 @cindex @code{equ} directive
3647 @cindex assigning values to symbols
3648 @cindex symbols, assigning values to
3649 This directive sets the value of @var{symbol} to @var{expression}.
3650 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3653 The syntax for @code{equ} on the HPPA is
3654 @samp{@var{symbol} .equ @var{expression}}.
3658 @section @code{.equiv @var{symbol}, @var{expression}}
3659 @cindex @code{equiv} directive
3660 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
3661 the assembler will signal an error if @var{symbol} is already defined.
3663 Except for the contents of the error message, this is roughly equivalent to
3672 @section @code{.err}
3673 @cindex @code{err} directive
3674 If @code{@value{AS}} assembles a @code{.err} directive, it will print an error
3675 message and, unless the @code{-Z} option was used, it will not generate an
3676 object file. This can be used to signal error an conditionally compiled code.
3679 @section @code{.exitm}
3680 Exit early from the current macro definition. @xref{Macro}.
3683 @section @code{.extern}
3685 @cindex @code{extern} directive
3686 @code{.extern} is accepted in the source program---for compatibility
3687 with other assemblers---but it is ignored. @code{@value{AS}} treats
3688 all undefined symbols as external.
3691 @section @code{.fail @var{expression}}
3693 @cindex @code{fail} directive
3694 Generates an error or a warning. If the value of the @var{expression} is 500
3695 or more, @code{@value{AS}} will print a warning message. If the value is less
3696 than 500, @code{@value{AS}} will print an error message. The message will
3697 include the value of @var{expression}. This can occasionally be useful inside
3698 complex nested macros or conditional assembly.
3700 @ifclear no-file-dir
3702 @section @code{.file @var{string}}
3704 @cindex @code{file} directive
3705 @cindex logical file name
3706 @cindex file name, logical
3707 @code{.file} tells @code{@value{AS}} that we are about to start a new logical
3708 file. @var{string} is the new file name. In general, the filename is
3709 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
3710 to specify an empty file name, you must give the quotes--@code{""}. This
3711 statement may go away in future: it is only recognized to be compatible with
3712 old @code{@value{AS}} programs.
3714 In some configurations of @code{@value{AS}}, @code{.file} has already been
3715 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
3720 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
3722 @cindex @code{fill} directive
3723 @cindex writing patterns in memory
3724 @cindex patterns, writing in memory
3725 @var{result}, @var{size} and @var{value} are absolute expressions.
3726 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
3727 may be zero or more. @var{Size} may be zero or more, but if it is
3728 more than 8, then it is deemed to have the value 8, compatible with
3729 other people's assemblers. The contents of each @var{repeat} bytes
3730 is taken from an 8-byte number. The highest order 4 bytes are
3731 zero. The lowest order 4 bytes are @var{value} rendered in the
3732 byte-order of an integer on the computer @code{@value{AS}} is assembling for.
3733 Each @var{size} bytes in a repetition is taken from the lowest order
3734 @var{size} bytes of this number. Again, this bizarre behavior is
3735 compatible with other people's assemblers.
3737 @var{size} and @var{value} are optional.
3738 If the second comma and @var{value} are absent, @var{value} is
3739 assumed zero. If the first comma and following tokens are absent,
3740 @var{size} is assumed to be 1.
3743 @section @code{.float @var{flonums}}
3745 @cindex floating point numbers (single)
3746 @cindex @code{float} directive
3747 This directive assembles zero or more flonums, separated by commas. It
3748 has the same effect as @code{.single}.
3750 The exact kind of floating point numbers emitted depends on how
3751 @code{@value{AS}} is configured.
3752 @xref{Machine Dependencies}.
3756 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
3757 in @sc{ieee} format.
3762 @section @code{.func @var{name}[,@var{label}]}
3763 @cindex @code{func} directive
3764 @code{.func} emits debugging information to denote function @var{name}, and
3765 is ignored unless the file is assembled with debugging enabled.
3766 Only @samp{--gstabs} is currently supported.
3767 @var{label} is the entry point of the function and if omitted @var{name}
3768 prepended with the @samp{leading char} is used.
3769 @samp{leading char} is usually @code{_} or nothing, depending on the target.
3770 All functions are currently defined to have @code{void} return type.
3771 The function must be terminated with @code{.endfunc}.
3774 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3776 @cindex @code{global} directive
3777 @cindex symbol, making visible to linker
3778 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
3779 @var{symbol} in your partial program, its value is made available to
3780 other partial programs that are linked with it. Otherwise,
3781 @var{symbol} takes its attributes from a symbol of the same name
3782 from another file linked into the same program.
3784 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
3785 compatibility with other assemblers.
3788 On the HPPA, @code{.global} is not always enough to make it accessible to other
3789 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
3790 @xref{HPPA Directives,, HPPA Assembler Directives}.
3795 @section @code{.hidden @var{names}}
3797 @cindex @code{.hidden} directive
3799 This one of the ELF visibility directives. The other two are
3800 @pxref{Internal,,@code{.internal}} and @pxref{Protected,,@code{.protected}}
3802 This directive overrides the named symbols default visibility (which is set by
3803 their binding: local, global or weak). The directive sets the visibility to
3804 @code{hidden} which means that the symbols are not visible to other components.
3805 Such symbols are always considered to be @code{protected} as well.
3809 @section @code{.hword @var{expressions}}
3811 @cindex @code{hword} directive
3812 @cindex integers, 16-bit
3813 @cindex numbers, 16-bit
3814 @cindex sixteen bit integers
3815 This expects zero or more @var{expressions}, and emits
3816 a 16 bit number for each.
3819 This directive is a synonym for @samp{.short}; depending on the target
3820 architecture, it may also be a synonym for @samp{.word}.
3824 This directive is a synonym for @samp{.short}.
3827 This directive is a synonym for both @samp{.short} and @samp{.word}.
3832 @section @code{.ident}
3834 @cindex @code{ident} directive
3835 This directive is used by some assemblers to place tags in object files.
3836 @code{@value{AS}} simply accepts the directive for source-file
3837 compatibility with such assemblers, but does not actually emit anything
3841 @section @code{.if @var{absolute expression}}
3843 @cindex conditional assembly
3844 @cindex @code{if} directive
3845 @code{.if} marks the beginning of a section of code which is only
3846 considered part of the source program being assembled if the argument
3847 (which must be an @var{absolute expression}) is non-zero. The end of
3848 the conditional section of code must be marked by @code{.endif}
3849 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
3850 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
3851 If you have several conditions to check, @code{.elseif} may be used to avoid
3852 nesting blocks if/else within each subsequent @code{.else} block.
3854 The following variants of @code{.if} are also supported:
3856 @cindex @code{ifdef} directive
3857 @item .ifdef @var{symbol}
3858 Assembles the following section of code if the specified @var{symbol}
3861 @cindex @code{ifc} directive
3862 @item .ifc @var{string1},@var{string2}
3863 Assembles the following section of code if the two strings are the same. The
3864 strings may be optionally quoted with single quotes. If they are not quoted,
3865 the first string stops at the first comma, and the second string stops at the
3866 end of the line. Strings which contain whitespace should be quoted. The
3867 string comparison is case sensitive.
3869 @cindex @code{ifeq} directive
3870 @item .ifeq @var{absolute expression}
3871 Assembles the following section of code if the argument is zero.
3873 @cindex @code{ifeqs} directive
3874 @item .ifeqs @var{string1},@var{string2}
3875 Another form of @code{.ifc}. The strings must be quoted using double quotes.
3877 @cindex @code{ifge} directive
3878 @item .ifge @var{absolute expression}
3879 Assembles the following section of code if the argument is greater than or
3882 @cindex @code{ifgt} directive
3883 @item .ifgt @var{absolute expression}
3884 Assembles the following section of code if the argument is greater than zero.
3886 @cindex @code{ifle} directive
3887 @item .ifle @var{absolute expression}
3888 Assembles the following section of code if the argument is less than or equal
3891 @cindex @code{iflt} directive
3892 @item .iflt @var{absolute expression}
3893 Assembles the following section of code if the argument is less than zero.
3895 @cindex @code{ifnc} directive
3896 @item .ifnc @var{string1},@var{string2}.
3897 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
3898 following section of code if the two strings are not the same.
3900 @cindex @code{ifndef} directive
3901 @cindex @code{ifnotdef} directive
3902 @item .ifndef @var{symbol}
3903 @itemx .ifnotdef @var{symbol}
3904 Assembles the following section of code if the specified @var{symbol}
3905 has not been defined. Both spelling variants are equivalent.
3907 @cindex @code{ifne} directive
3908 @item .ifne @var{absolute expression}
3909 Assembles the following section of code if the argument is not equal to zero
3910 (in other words, this is equivalent to @code{.if}).
3912 @cindex @code{ifnes} directive
3913 @item .ifnes @var{string1},@var{string2}
3914 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
3915 following section of code if the two strings are not the same.
3919 @section @code{.include "@var{file}"}
3921 @cindex @code{include} directive
3922 @cindex supporting files, including
3923 @cindex files, including
3924 This directive provides a way to include supporting files at specified
3925 points in your source program. The code from @var{file} is assembled as
3926 if it followed the point of the @code{.include}; when the end of the
3927 included file is reached, assembly of the original file continues. You
3928 can control the search paths used with the @samp{-I} command-line option
3929 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
3933 @section @code{.int @var{expressions}}
3935 @cindex @code{int} directive
3936 @cindex integers, 32-bit
3937 Expect zero or more @var{expressions}, of any section, separated by commas.
3938 For each expression, emit a number that, at run time, is the value of that
3939 expression. The byte order and bit size of the number depends on what kind
3940 of target the assembly is for.
3944 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
3945 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
3952 @section @code{.internal @var{names}}
3954 @cindex @code{.internal} directive
3956 This one of the ELF visibility directives. The other two are
3957 @pxref{Hidden,,@code{.hidden}} and @pxref{Protected,,@code{.protected}}
3959 This directive overrides the named symbols default visibility (which is set by
3960 their binding: local, global or weak). The directive sets the visibility to
3961 @code{internal} which means that the symbols are considered to be @code{hidden}
3962 (ie not visible to other components), and that some extra, processor specific
3963 processing must also be performed upon the symbols as well.
3967 @section @code{.irp @var{symbol},@var{values}}@dots{}
3969 @cindex @code{irp} directive
3970 Evaluate a sequence of statements assigning different values to @var{symbol}.
3971 The sequence of statements starts at the @code{.irp} directive, and is
3972 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
3973 set to @var{value}, and the sequence of statements is assembled. If no
3974 @var{value} is listed, the sequence of statements is assembled once, with
3975 @var{symbol} set to the null string. To refer to @var{symbol} within the
3976 sequence of statements, use @var{\symbol}.
3978 For example, assembling
3986 is equivalent to assembling
3995 @section @code{.irpc @var{symbol},@var{values}}@dots{}
3997 @cindex @code{irpc} directive
3998 Evaluate a sequence of statements assigning different values to @var{symbol}.
3999 The sequence of statements starts at the @code{.irpc} directive, and is
4000 terminated by an @code{.endr} directive. For each character in @var{value},
4001 @var{symbol} is set to the character, and the sequence of statements is
4002 assembled. If no @var{value} is listed, the sequence of statements is
4003 assembled once, with @var{symbol} set to the null string. To refer to
4004 @var{symbol} within the sequence of statements, use @var{\symbol}.
4006 For example, assembling
4014 is equivalent to assembling
4023 @section @code{.lcomm @var{symbol} , @var{length}}
4025 @cindex @code{lcomm} directive
4026 @cindex local common symbols
4027 @cindex symbols, local common
4028 Reserve @var{length} (an absolute expression) bytes for a local common
4029 denoted by @var{symbol}. The section and value of @var{symbol} are
4030 those of the new local common. The addresses are allocated in the bss
4031 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4032 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4033 not visible to @code{@value{LD}}.
4036 Some targets permit a third argument to be used with @code{.lcomm}. This
4037 argument specifies the desired alignment of the symbol in the bss section.
4041 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4042 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4046 @section @code{.lflags}
4048 @cindex @code{lflags} directive (ignored)
4049 @code{@value{AS}} accepts this directive, for compatibility with other
4050 assemblers, but ignores it.
4052 @ifclear no-line-dir
4054 @section @code{.line @var{line-number}}
4056 @cindex @code{line} directive
4060 @section @code{.ln @var{line-number}}
4062 @cindex @code{ln} directive
4064 @cindex logical line number
4066 Change the logical line number. @var{line-number} must be an absolute
4067 expression. The next line has that logical line number. Therefore any other
4068 statements on the current line (after a statement separator character) are
4069 reported as on logical line number @var{line-number} @minus{} 1. One day
4070 @code{@value{AS}} will no longer support this directive: it is recognized only
4071 for compatibility with existing assembler programs.
4075 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4076 not available; use the synonym @code{.ln} in that context.
4081 @ifclear no-line-dir
4082 Even though this is a directive associated with the @code{a.out} or
4083 @code{b.out} object-code formats, @code{@value{AS}} still recognizes it
4084 when producing COFF output, and treats @samp{.line} as though it
4085 were the COFF @samp{.ln} @emph{if} it is found outside a
4086 @code{.def}/@code{.endef} pair.
4088 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4089 used by compilers to generate auxiliary symbol information for
4094 @section @code{.linkonce [@var{type}]}
4096 @cindex @code{linkonce} directive
4097 @cindex common sections
4098 Mark the current section so that the linker only includes a single copy of it.
4099 This may be used to include the same section in several different object files,
4100 but ensure that the linker will only include it once in the final output file.
4101 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4102 Duplicate sections are detected based on the section name, so it should be
4105 This directive is only supported by a few object file formats; as of this
4106 writing, the only object file format which supports it is the Portable
4107 Executable format used on Windows NT.
4109 The @var{type} argument is optional. If specified, it must be one of the
4110 following strings. For example:
4114 Not all types may be supported on all object file formats.
4118 Silently discard duplicate sections. This is the default.
4121 Warn if there are duplicate sections, but still keep only one copy.
4124 Warn if any of the duplicates have different sizes.
4127 Warn if any of the duplicates do not have exactly the same contents.
4131 @section @code{.ln @var{line-number}}
4133 @cindex @code{ln} directive
4134 @ifclear no-line-dir
4135 @samp{.ln} is a synonym for @samp{.line}.
4138 Tell @code{@value{AS}} to change the logical line number. @var{line-number}
4139 must be an absolute expression. The next line has that logical
4140 line number, so any other statements on the current line (after a
4141 statement separator character @code{;}) are reported as on logical
4142 line number @var{line-number} @minus{} 1.
4145 This directive is accepted, but ignored, when @code{@value{AS}} is
4146 configured for @code{b.out}; its effect is only associated with COFF
4152 @section @code{.mri @var{val}}
4154 @cindex @code{mri} directive
4155 @cindex MRI mode, temporarily
4156 If @var{val} is non-zero, this tells @code{@value{AS}} to enter MRI mode. If
4157 @var{val} is zero, this tells @code{@value{AS}} to exit MRI mode. This change
4158 affects code assembled until the next @code{.mri} directive, or until the end
4159 of the file. @xref{M, MRI mode, MRI mode}.
4162 @section @code{.list}
4164 @cindex @code{list} directive
4165 @cindex listing control, turning on
4166 Control (in conjunction with the @code{.nolist} directive) whether or
4167 not assembly listings are generated. These two directives maintain an
4168 internal counter (which is zero initially). @code{.list} increments the
4169 counter, and @code{.nolist} decrements it. Assembly listings are
4170 generated whenever the counter is greater than zero.
4172 By default, listings are disabled. When you enable them (with the
4173 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4174 the initial value of the listing counter is one.
4177 @section @code{.long @var{expressions}}
4179 @cindex @code{long} directive
4180 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4183 @c no one seems to know what this is for or whether this description is
4184 @c what it really ought to do
4186 @section @code{.lsym @var{symbol}, @var{expression}}
4188 @cindex @code{lsym} directive
4189 @cindex symbol, not referenced in assembly
4190 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4191 the hash table, ensuring it cannot be referenced by name during the
4192 rest of the assembly. This sets the attributes of the symbol to be
4193 the same as the expression value:
4195 @var{other} = @var{descriptor} = 0
4196 @var{type} = @r{(section of @var{expression})}
4197 @var{value} = @var{expression}
4200 The new symbol is not flagged as external.
4204 @section @code{.macro}
4207 The commands @code{.macro} and @code{.endm} allow you to define macros that
4208 generate assembly output. For example, this definition specifies a macro
4209 @code{sum} that puts a sequence of numbers into memory:
4212 .macro sum from=0, to=5
4221 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4233 @item .macro @var{macname}
4234 @itemx .macro @var{macname} @var{macargs} @dots{}
4235 @cindex @code{macro} directive
4236 Begin the definition of a macro called @var{macname}. If your macro
4237 definition requires arguments, specify their names after the macro name,
4238 separated by commas or spaces. You can supply a default value for any
4239 macro argument by following the name with @samp{=@var{deflt}}. For
4240 example, these are all valid @code{.macro} statements:
4244 Begin the definition of a macro called @code{comm}, which takes no
4247 @item .macro plus1 p, p1
4248 @itemx .macro plus1 p p1
4249 Either statement begins the definition of a macro called @code{plus1},
4250 which takes two arguments; within the macro definition, write
4251 @samp{\p} or @samp{\p1} to evaluate the arguments.
4253 @item .macro reserve_str p1=0 p2
4254 Begin the definition of a macro called @code{reserve_str}, with two
4255 arguments. The first argument has a default value, but not the second.
4256 After the definition is complete, you can call the macro either as
4257 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4258 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4259 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4260 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4263 When you call a macro, you can specify the argument values either by
4264 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4265 @samp{sum to=17, from=9}.
4268 @cindex @code{endm} directive
4269 Mark the end of a macro definition.
4272 @cindex @code{exitm} directive
4273 Exit early from the current macro definition.
4275 @cindex number of macros executed
4276 @cindex macros, count executed
4278 @code{@value{AS}} maintains a counter of how many macros it has
4279 executed in this pseudo-variable; you can copy that number to your
4280 output with @samp{\@@}, but @emph{only within a macro definition}.
4283 @item LOCAL @var{name} [ , @dots{} ]
4284 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4285 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4286 Alternate macro syntax}.
4288 Generate a string replacement for each of the @var{name} arguments, and
4289 replace any instances of @var{name} in each macro expansion. The
4290 replacement string is unique in the assembly, and different for each
4291 separate macro expansion. @code{LOCAL} allows you to write macros that
4292 define symbols, without fear of conflict between separate macro expansions.
4297 @section @code{.nolist}
4299 @cindex @code{nolist} directive
4300 @cindex listing control, turning off
4301 Control (in conjunction with the @code{.list} directive) whether or
4302 not assembly listings are generated. These two directives maintain an
4303 internal counter (which is zero initially). @code{.list} increments the
4304 counter, and @code{.nolist} decrements it. Assembly listings are
4305 generated whenever the counter is greater than zero.
4308 @section @code{.octa @var{bignums}}
4310 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4311 @cindex @code{octa} directive
4312 @cindex integer, 16-byte
4313 @cindex sixteen byte integer
4314 This directive expects zero or more bignums, separated by commas. For each
4315 bignum, it emits a 16-byte integer.
4317 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4318 hence @emph{octa}-word for 16 bytes.
4321 @section @code{.org @var{new-lc} , @var{fill}}
4323 @cindex @code{org} directive
4324 @cindex location counter, advancing
4325 @cindex advancing location counter
4326 @cindex current address, advancing
4327 Advance the location counter of the current section to
4328 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4329 expression with the same section as the current subsection. That is,
4330 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4331 wrong section, the @code{.org} directive is ignored. To be compatible
4332 with former assemblers, if the section of @var{new-lc} is absolute,
4333 @code{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4334 is the same as the current subsection.
4336 @code{.org} may only increase the location counter, or leave it
4337 unchanged; you cannot use @code{.org} to move the location counter
4340 @c double negative used below "not undefined" because this is a specific
4341 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4342 @c section. doc@cygnus.com 18feb91
4343 Because @code{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4344 may not be undefined. If you really detest this restriction we eagerly await
4345 a chance to share your improved assembler.
4347 Beware that the origin is relative to the start of the section, not
4348 to the start of the subsection. This is compatible with other
4349 people's assemblers.
4351 When the location counter (of the current subsection) is advanced, the
4352 intervening bytes are filled with @var{fill} which should be an
4353 absolute expression. If the comma and @var{fill} are omitted,
4354 @var{fill} defaults to zero.
4357 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4359 @cindex padding the location counter given a power of two
4360 @cindex @code{p2align} directive
4361 Pad the location counter (in the current subsection) to a particular
4362 storage boundary. The first expression (which must be absolute) is the
4363 number of low-order zero bits the location counter must have after
4364 advancement. For example @samp{.p2align 3} advances the location
4365 counter until it a multiple of 8. If the location counter is already a
4366 multiple of 8, no change is needed.
4368 The second expression (also absolute) gives the fill value to be stored in the
4369 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4370 padding bytes are normally zero. However, on some systems, if the section is
4371 marked as containing code and the fill value is omitted, the space is filled
4372 with no-op instructions.
4374 The third expression is also absolute, and is also optional. If it is present,
4375 it is the maximum number of bytes that should be skipped by this alignment
4376 directive. If doing the alignment would require skipping more bytes than the
4377 specified maximum, then the alignment is not done at all. You can omit the
4378 fill value (the second argument) entirely by simply using two commas after the
4379 required alignment; this can be useful if you want the alignment to be filled
4380 with no-op instructions when appropriate.
4382 @cindex @code{p2alignw} directive
4383 @cindex @code{p2alignl} directive
4384 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4385 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4386 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4387 fill pattern as a four byte longword value. For example, @code{.p2alignw
4388 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4389 filled in with the value 0x368d (the exact placement of the bytes depends upon
4390 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4395 @section @code{.previous}
4397 @cindex @code{.previous} directive
4398 @cindex Section Stack
4399 This is one of the ELF section stack manipulation directives. The others are
4400 @pxref{Section}, @xref{SubSection}, @pxref{PushSection}, and
4403 This directive swaps the current section (and subsection) with most recently
4404 referenced section (and subsection) prior to this one. Multiple
4405 @code{.previous} directives in a row will flip between two sections (and their
4408 In terms of the section stack, this directive swaps the current section with
4409 the top section on the section stack.
4414 @section @code{.popsection}
4416 @cindex @code{.popsection} directive
4417 @cindex Section Stack
4418 This is one of the ELF section stack manipulation directives. The others are
4419 @pxref{Section}, @xref{SubSection}, @pxref{PushSection}, and
4422 This directive replaces the current section (and subsection) with the top
4423 section (and subsection) on the section stack. This section is popped off the
4428 @section @code{.print @var{string}}
4430 @cindex @code{print} directive
4431 @code{@value{AS}} will print @var{string} on the standard output during
4432 assembly. You must put @var{string} in double quotes.
4436 @section @code{.protected @var{names}}
4438 @cindex @code{.protected} directive
4440 This one of the ELF visibility directives. The other two are
4441 @pxref{Hidden} and @pxref{Internal}
4443 This directive overrides the named symbols default visibility (which is set by
4444 their binding: local, global or weak). The directive sets the visibility to
4445 @code{protected} which means that any references to the symbols from within the
4446 components that defines them must be resolved to the definition in that
4447 component, even if a definition in another component would normally preempt
4452 @section @code{.psize @var{lines} , @var{columns}}
4454 @cindex @code{psize} directive
4455 @cindex listing control: paper size
4456 @cindex paper size, for listings
4457 Use this directive to declare the number of lines---and, optionally, the
4458 number of columns---to use for each page, when generating listings.
4460 If you do not use @code{.psize}, listings use a default line-count
4461 of 60. You may omit the comma and @var{columns} specification; the
4462 default width is 200 columns.
4464 @code{@value{AS}} generates formfeeds whenever the specified number of
4465 lines is exceeded (or whenever you explicitly request one, using
4468 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4469 those explicitly specified with @code{.eject}.
4472 @section @code{.purgem @var{name}}
4474 @cindex @code{purgem} directive
4475 Undefine the macro @var{name}, so that later uses of the string will not be
4476 expanded. @xref{Macro}.
4480 @section @code{.pushsection @var{name} , @var{subsection}}
4482 @cindex @code{.pushsection} directive
4483 @cindex Section Stack
4484 This is one of the ELF section stack manipulation directives. The others are
4485 @pxref{Section}, @xref{SubSection}, @pxref{PopSection}, and
4488 This directive is a synonym for @code{.section}. It psuhes the current section
4489 (and subsection) onto the top of the section stack, and then replaces the
4490 current section and subsection with @code{name} and @code{subsection}.
4494 @section @code{.quad @var{bignums}}
4496 @cindex @code{quad} directive
4497 @code{.quad} expects zero or more bignums, separated by commas. For
4498 each bignum, it emits
4500 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4501 warning message; and just takes the lowest order 8 bytes of the bignum.
4502 @cindex eight-byte integer
4503 @cindex integer, 8-byte
4505 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4506 hence @emph{quad}-word for 8 bytes.
4509 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4510 warning message; and just takes the lowest order 16 bytes of the bignum.
4511 @cindex sixteen-byte integer
4512 @cindex integer, 16-byte
4516 @section @code{.rept @var{count}}
4518 @cindex @code{rept} directive
4519 Repeat the sequence of lines between the @code{.rept} directive and the next
4520 @code{.endr} directive @var{count} times.
4522 For example, assembling
4530 is equivalent to assembling
4539 @section @code{.sbttl "@var{subheading}"}
4541 @cindex @code{sbttl} directive
4542 @cindex subtitles for listings
4543 @cindex listing control: subtitle
4544 Use @var{subheading} as the title (third line, immediately after the
4545 title line) when generating assembly listings.
4547 This directive affects subsequent pages, as well as the current page if
4548 it appears within ten lines of the top of a page.
4552 @section @code{.scl @var{class}}
4554 @cindex @code{scl} directive
4555 @cindex symbol storage class (COFF)
4556 @cindex COFF symbol storage class
4557 Set the storage-class value for a symbol. This directive may only be
4558 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4559 whether a symbol is static or external, or it may record further
4560 symbolic debugging information.
4563 The @samp{.scl} directive is primarily associated with COFF output; when
4564 configured to generate @code{b.out} output format, @code{@value{AS}}
4565 accepts this directive but ignores it.
4570 @section @code{.section @var{name}} (COFF version)
4572 @cindex @code{section} directive
4573 @cindex named section
4574 Use the @code{.section} directive to assemble the following code into a section
4577 This directive is only supported for targets that actually support arbitrarily
4578 named sections; on @code{a.out} targets, for example, it is not accepted, even
4579 with a standard @code{a.out} section name.
4581 For COFF targets, the @code{.section} directive is used in one of the following
4585 .section @var{name}[, "@var{flags}"]
4586 .section @var{name}[, @var{subsegment}]
4589 If the optional argument is quoted, it is taken as flags to use for the
4590 section. Each flag is a single character. The following flags are recognized:
4593 bss section (uninitialized data)
4595 section is not loaded
4605 shared section (meaningful for PE targets)
4608 If no flags are specified, the default flags depend upon the section name. If
4609 the section name is not recognized, the default will be for the section to be
4610 loaded and writable.
4612 If the optional argument to the @code{.section} directive is not quoted, it is
4613 taken as a subsegment number (@pxref{Sub-Sections}).
4616 @section @code{.section @var{name}} (ELF version)
4618 @cindex @code{section} directive
4619 @cindex named section
4621 @cindex Section Stack
4622 This is one of the ELF section stack manipulation directives. The others are
4623 @xref{SubSection}, @pxref{PushSection}@pxref{PopSection}, and
4627 For ELF targets, the @code{.section} directive is used like this:
4630 .section @var{name} [, "@var{flags}"[, @@@var{type}]]
4633 The optional @var{flags} argument is a quoted string which may contain any
4634 combintion of the following characters:
4637 section is allocatable
4641 section is executable
4644 The optional @var{type} argument may contain one of the following constants:
4647 section contains data
4649 section does not contain data (i.e., section only occupies space)
4652 If no flags are specified, the default flags depend upon the section name. If
4653 the section name is not recognized, the default will be for the section to have
4654 none of the above flags: it will not be allocated in memory, nor writable, nor
4655 executable. The section will contain data.
4657 For ELF targets, the assembler supports another type of @code{.section}
4658 directive for compatibility with the Solaris assembler:
4661 .section "@var{name}"[, @var{flags}...]
4664 Note that the section name is quoted. There may be a sequence of comma
4668 section is allocatable
4672 section is executable
4675 This directive replaces the current section and subsection. The replaced
4676 section and subsection are pushed onto the section stack. See the contents of
4677 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
4678 how this directive and the other section stack directives work.
4681 @section @code{.set @var{symbol}, @var{expression}}
4683 @cindex @code{set} directive
4684 @cindex symbol value, setting
4685 Set the value of @var{symbol} to @var{expression}. This
4686 changes @var{symbol}'s value and type to conform to
4687 @var{expression}. If @var{symbol} was flagged as external, it remains
4688 flagged (@pxref{Symbol Attributes}).
4690 You may @code{.set} a symbol many times in the same assembly.
4692 If you @code{.set} a global symbol, the value stored in the object
4693 file is the last value stored into it.
4696 The syntax for @code{set} on the HPPA is
4697 @samp{@var{symbol} .set @var{expression}}.
4701 @section @code{.short @var{expressions}}
4703 @cindex @code{short} directive
4705 @code{.short} is normally the same as @samp{.word}.
4706 @xref{Word,,@code{.word}}.
4708 In some configurations, however, @code{.short} and @code{.word} generate
4709 numbers of different lengths; @pxref{Machine Dependencies}.
4713 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
4716 This expects zero or more @var{expressions}, and emits
4717 a 16 bit number for each.
4722 @section @code{.single @var{flonums}}
4724 @cindex @code{single} directive
4725 @cindex floating point numbers (single)
4726 This directive assembles zero or more flonums, separated by commas. It
4727 has the same effect as @code{.float}.
4729 The exact kind of floating point numbers emitted depends on how
4730 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
4734 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
4735 numbers in @sc{ieee} format.
4740 @section @code{.size} (COFF version)
4742 @cindex @code{size} directive
4743 This directive is generated by compilers to include auxiliary debugging
4744 information in the symbol table. It is only permitted inside
4745 @code{.def}/@code{.endef} pairs.
4748 @samp{.size} is only meaningful when generating COFF format output; when
4749 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
4753 @section @code{.size @var{name} , @var{expression}} (ELF version)
4754 @cindex @code{size} directive
4756 This directive is used to set the size associated with a symbol @var{name}.
4757 The size in bytes is computed from @var{expression} which can make use of label
4758 arithmetic. This directive is typically used to set the size of function
4762 @section @code{.sleb128 @var{expressions}}
4764 @cindex @code{sleb128} directive
4765 @var{sleb128} stands for ``signed little endian base 128.'' This is a
4766 compact, variable length representation of numbers used by the DWARF
4767 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
4769 @ifclear no-space-dir
4771 @section @code{.skip @var{size} , @var{fill}}
4773 @cindex @code{skip} directive
4774 @cindex filling memory
4775 This directive emits @var{size} bytes, each of value @var{fill}. Both
4776 @var{size} and @var{fill} are absolute expressions. If the comma and
4777 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
4781 @section @code{.space @var{size} , @var{fill}}
4783 @cindex @code{space} directive
4784 @cindex filling memory
4785 This directive emits @var{size} bytes, each of value @var{fill}. Both
4786 @var{size} and @var{fill} are absolute expressions. If the comma
4787 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
4792 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
4793 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
4794 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
4795 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
4804 @section @code{.space}
4805 @cindex @code{space} directive
4807 On the AMD 29K, this directive is ignored; it is accepted for
4808 compatibility with other AMD 29K assemblers.
4811 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
4812 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
4818 @section @code{.stabd, .stabn, .stabs}
4820 @cindex symbolic debuggers, information for
4821 @cindex @code{stab@var{x}} directives
4822 There are three directives that begin @samp{.stab}.
4823 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
4824 The symbols are not entered in the @code{@value{AS}} hash table: they
4825 cannot be referenced elsewhere in the source file.
4826 Up to five fields are required:
4830 This is the symbol's name. It may contain any character except
4831 @samp{\000}, so is more general than ordinary symbol names. Some
4832 debuggers used to code arbitrarily complex structures into symbol names
4836 An absolute expression. The symbol's type is set to the low 8 bits of
4837 this expression. Any bit pattern is permitted, but @code{@value{LD}}
4838 and debuggers choke on silly bit patterns.
4841 An absolute expression. The symbol's ``other'' attribute is set to the
4842 low 8 bits of this expression.
4845 An absolute expression. The symbol's descriptor is set to the low 16
4846 bits of this expression.
4849 An absolute expression which becomes the symbol's value.
4852 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
4853 or @code{.stabs} statement, the symbol has probably already been created;
4854 you get a half-formed symbol in your object file. This is
4855 compatible with earlier assemblers!
4858 @cindex @code{stabd} directive
4859 @item .stabd @var{type} , @var{other} , @var{desc}
4861 The ``name'' of the symbol generated is not even an empty string.
4862 It is a null pointer, for compatibility. Older assemblers used a
4863 null pointer so they didn't waste space in object files with empty
4866 The symbol's value is set to the location counter,
4867 relocatably. When your program is linked, the value of this symbol
4868 is the address of the location counter when the @code{.stabd} was
4871 @cindex @code{stabn} directive
4872 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
4873 The name of the symbol is set to the empty string @code{""}.
4875 @cindex @code{stabs} directive
4876 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
4877 All five fields are specified.
4883 @section @code{.string} "@var{str}"
4885 @cindex string, copying to object file
4886 @cindex @code{string} directive
4888 Copy the characters in @var{str} to the object file. You may specify more than
4889 one string to copy, separated by commas. Unless otherwise specified for a
4890 particular machine, the assembler marks the end of each string with a 0 byte.
4891 You can use any of the escape sequences described in @ref{Strings,,Strings}.
4894 @section @code{.struct @var{expression}}
4896 @cindex @code{struct} directive
4897 Switch to the absolute section, and set the section offset to @var{expression},
4898 which must be an absolute expression. You might use this as follows:
4907 This would define the symbol @code{field1} to have the value 0, the symbol
4908 @code{field2} to have the value 4, and the symbol @code{field3} to have the
4909 value 8. Assembly would be left in the absolute section, and you would need to
4910 use a @code{.section} directive of some sort to change to some other section
4911 before further assembly.
4915 @section @code{.subsection @var{name}}
4917 @cindex @code{.subsection} directive
4918 @cindex Section Stack
4919 This is one of the ELF section stack manipulation directives. The others are
4920 @pxref{Section}, @xref{PushSection}, @pxref{PopSection}, and
4923 This directive replaces the current subsection with @code{name}. The current
4924 section is not changed. The replaced subsection is put onto the section stack
4925 in place of the then current top of stack subsection.
4930 @section @code{.symver}
4931 @cindex @code{symver} directive
4932 @cindex symbol versioning
4933 @cindex versions of symbols
4934 Use the @code{.symver} directive to bind symbols to specific version nodes
4935 within a source file. This is only supported on ELF platforms, and is
4936 typically used when assembling files to be linked into a shared library.
4937 There are cases where it may make sense to use this in objects to be bound
4938 into an application itself so as to override a versioned symbol from a
4941 For ELF targets, the @code{.symver} directive can be used like this:
4943 .symver @var{name}, @var{name2@@nodename}
4945 If the symbol @var{name} is defined within the file
4946 being assembled, the @code{.symver} directive effectively creates a symbol
4947 alias with the name @var{name2@@nodename}, and in fact the main reason that we
4948 just don't try and create a regular alias is that the @var{@@} character isn't
4949 permitted in symbol names. The @var{name2} part of the name is the actual name
4950 of the symbol by which it will be externally referenced. The name @var{name}
4951 itself is merely a name of convenience that is used so that it is possible to
4952 have definitions for multiple versions of a function within a single source
4953 file, and so that the compiler can unambiguously know which version of a
4954 function is being mentioned. The @var{nodename} portion of the alias should be
4955 the name of a node specified in the version script supplied to the linker when
4956 building a shared library. If you are attempting to override a versioned
4957 symbol from a shared library, then @var{nodename} should correspond to the
4958 nodename of the symbol you are trying to override.
4960 If the symbol @var{name} is not defined within the file being assembled, all
4961 references to @var{name} will be changed to @var{name2@@nodename}. If no
4962 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
4965 Another usage of the @code{.symver} directive is:
4967 .symver @var{name}, @var{name2@@@@nodename}
4969 In this case, the symbol @var{name} must exist and be defined within
4970 the file being assembled. It is similiar to @var{name2@@nodename}. The
4971 difference is @var{name2@@@@nodename} will also be used to resolve
4972 references to @var{name2} by the linker.
4974 The third usage of the @code{.symver} directive is:
4976 .symver @var{name}, @var{name2@@@@@@nodename}
4978 When @var{name} is not defined within the
4979 file being assembled, it is treated as @var{name2@@nodename}. When
4980 @var{name} is defined within the file being assembled, the symbol
4981 name, @var{name}, will be changed to @var{name2@@@@nodename}.
4986 @section @code{.tag @var{structname}}
4988 @cindex COFF structure debugging
4989 @cindex structure debugging, COFF
4990 @cindex @code{tag} directive
4991 This directive is generated by compilers to include auxiliary debugging
4992 information in the symbol table. It is only permitted inside
4993 @code{.def}/@code{.endef} pairs. Tags are used to link structure
4994 definitions in the symbol table with instances of those structures.
4997 @samp{.tag} is only used when generating COFF format output; when
4998 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
5004 @section @code{.text @var{subsection}}
5006 @cindex @code{text} directive
5007 Tells @code{@value{AS}} to assemble the following statements onto the end of
5008 the text subsection numbered @var{subsection}, which is an absolute
5009 expression. If @var{subsection} is omitted, subsection number zero
5013 @section @code{.title "@var{heading}"}
5015 @cindex @code{title} directive
5016 @cindex listing control: title line
5017 Use @var{heading} as the title (second line, immediately after the
5018 source file name and pagenumber) when generating assembly listings.
5020 This directive affects subsequent pages, as well as the current page if
5021 it appears within ten lines of the top of a page.
5024 @section @code{.type @var{int}} (COFF version)
5026 @cindex COFF symbol type
5027 @cindex symbol type, COFF
5028 @cindex @code{type} directive
5029 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5030 records the integer @var{int} as the type attribute of a symbol table entry.
5033 @samp{.type} is associated only with COFF format output; when
5034 @code{@value{AS}} is configured for @code{b.out} output, it accepts this
5035 directive but ignores it.
5038 @section @code{.type @var{name} , @var{type description}} (ELF version)
5040 @cindex ELF symbol type
5041 @cindex symbol type, ELF
5042 @cindex @code{type} directive
5043 This directive is used to set the type of symbol @var{name} to be either a
5044 function symbol or an ojbect symbol. There are five different syntaxes
5045 supported for the @var{type description} field, in order to provide
5046 comptability with various other assemblers. The syntaxes supported are:
5049 .type <name>,#function
5050 .type <name>,#object
5052 .type <name>,@@function
5053 .type <name>,@@object
5055 .type <name>,%function
5056 .type <name>,%object
5058 .type <name>,"function"
5059 .type <name>,"object"
5061 .type <name> STT_FUNCTION
5062 .type <name> STT_OBJECT
5066 @section @code{.uleb128 @var{expressions}}
5068 @cindex @code{uleb128} directive
5069 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5070 compact, variable length representation of numbers used by the DWARF
5071 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5075 @section @code{.val @var{addr}}
5077 @cindex @code{val} directive
5078 @cindex COFF value attribute
5079 @cindex value attribute, COFF
5080 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5081 records the address @var{addr} as the value attribute of a symbol table
5085 @samp{.val} is used only for COFF output; when @code{@value{AS}} is
5086 configured for @code{b.out}, it accepts this directive but ignores it.
5092 @section @code{.version "@var{string}"}
5094 @cindex @code{.version}
5095 This directive creates a @code{.note} section and places into it an ELF
5096 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5101 @section @code{.vtable_entry @var{table}, @var{offset}}
5103 @cindex @code{.vtable_entry}
5104 This directive finds or creates a symbol @code{table} and creates a
5105 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5108 @section @code{.vtable_inherit @var{child}, @var{parent}}
5110 @cindex @code{.vtable_inherit}
5111 This directive finds the symbol @code{child} and finds or creates the symbol
5112 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5113 parent whoes addend is the value of the child symbol. As a special case the
5114 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5119 @section @code{.weak @var{names}}
5121 @cindex @code{.weak}
5122 This directive sets the weak attribute on the comma seperated list of symbol
5123 @code{names}. If the symbols do not already exist, they will be created.
5127 @section @code{.word @var{expressions}}
5129 @cindex @code{word} directive
5130 This directive expects zero or more @var{expressions}, of any section,
5131 separated by commas.
5134 For each expression, @code{@value{AS}} emits a 32-bit number.
5137 For each expression, @code{@value{AS}} emits a 16-bit number.
5142 The size of the number emitted, and its byte order,
5143 depend on what target computer the assembly is for.
5146 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5147 @c happen---32-bit addressability, period; no long/short jumps.
5148 @ifset DIFF-TBL-KLUGE
5149 @cindex difference tables altered
5150 @cindex altered difference tables
5152 @emph{Warning: Special Treatment to support Compilers}
5156 Machines with a 32-bit address space, but that do less than 32-bit
5157 addressing, require the following special treatment. If the machine of
5158 interest to you does 32-bit addressing (or doesn't require it;
5159 @pxref{Machine Dependencies}), you can ignore this issue.
5162 In order to assemble compiler output into something that works,
5163 @code{@value{AS}} occasionlly does strange things to @samp{.word} directives.
5164 Directives of the form @samp{.word sym1-sym2} are often emitted by
5165 compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a
5166 directive of the form @samp{.word sym1-sym2}, and the difference between
5167 @code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}}
5168 creates a @dfn{secondary jump table}, immediately before the next label.
5169 This secondary jump table is preceded by a short-jump to the
5170 first byte after the secondary table. This short-jump prevents the flow
5171 of control from accidentally falling into the new table. Inside the
5172 table is a long-jump to @code{sym2}. The original @samp{.word}
5173 contains @code{sym1} minus the address of the long-jump to
5176 If there were several occurrences of @samp{.word sym1-sym2} before the
5177 secondary jump table, all of them are adjusted. If there was a
5178 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5179 long-jump to @code{sym4} is included in the secondary jump table,
5180 and the @code{.word} directives are adjusted to contain @code{sym3}
5181 minus the address of the long-jump to @code{sym4}; and so on, for as many
5182 entries in the original jump table as necessary.
5185 @emph{This feature may be disabled by compiling @code{@value{AS}} with the
5186 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5187 assembly language programmers.
5190 @c end DIFF-TBL-KLUGE
5193 @section Deprecated Directives
5195 @cindex deprecated directives
5196 @cindex obsolescent directives
5197 One day these directives won't work.
5198 They are included for compatibility with older assemblers.
5205 @node Machine Dependencies
5206 @chapter Machine Dependent Features
5208 @cindex machine dependencies
5209 The machine instruction sets are (almost by definition) different on
5210 each machine where @code{@value{AS}} runs. Floating point representations
5211 vary as well, and @code{@value{AS}} often supports a few additional
5212 directives or command-line options for compatibility with other
5213 assemblers on a particular platform. Finally, some versions of
5214 @code{@value{AS}} support special pseudo-instructions for branch
5217 This chapter discusses most of these differences, though it does not
5218 include details on any machine's instruction set. For details on that
5219 subject, see the hardware manufacturer's manual.
5223 * AMD29K-Dependent:: AMD 29K Dependent Features
5226 * ARC-Dependent:: ARC Dependent Features
5229 * ARM-Dependent:: ARM Dependent Features
5232 * D10V-Dependent:: D10V Dependent Features
5235 * D30V-Dependent:: D30V Dependent Features
5238 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5241 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5244 * HPPA-Dependent:: HPPA Dependent Features
5247 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5250 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5253 * i860-Dependent:: Intel 80860 Dependent Features
5256 * i960-Dependent:: Intel 80960 Dependent Features
5259 * M32R-Dependent:: M32R Dependent Features
5262 * M68K-Dependent:: M680x0 Dependent Features
5265 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5268 * MIPS-Dependent:: MIPS Dependent Features
5271 * SH-Dependent:: Hitachi SH Dependent Features
5274 * PJ-Dependent:: picoJava Dependent Features
5277 * Sparc-Dependent:: SPARC Dependent Features
5280 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5283 * V850-Dependent:: V850 Dependent Features
5286 * Z8000-Dependent:: Z8000 Dependent Features
5289 * Vax-Dependent:: VAX Dependent Features
5296 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5297 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5298 @c peculiarity: to preserve cross-references, there must be a node called
5299 @c "Machine Dependencies". Hence the conditional nodenames in each
5300 @c major node below. Node defaulting in makeinfo requires adjacency of
5301 @c node and sectioning commands; hence the repetition of @chapter BLAH
5302 @c in both conditional blocks.
5308 @chapter ARC Dependent Features
5311 @node Machine Dependencies
5312 @chapter ARC Dependent Features
5317 * ARC-Opts:: Options
5318 * ARC-Float:: Floating Point
5319 * ARC-Directives:: Sparc Machine Directives
5325 @cindex options for ARC
5327 @cindex architectures, ARC
5328 @cindex ARC architectures
5329 The ARC chip family includes several successive levels (or other
5330 variants) of chip, using the same core instruction set, but including
5331 a few additional instructions at each level.
5333 By default, @code{@value{AS}} assumes the core instruction set (ARC
5334 base). The @code{.cpu} pseudo-op is intended to be used to select
5338 @cindex @code{-mbig-endian} option (ARC)
5339 @cindex @code{-mlittle-endian} option (ARC)
5340 @cindex ARC big-endian output
5341 @cindex ARC little-endian output
5342 @cindex big-endian output, ARC
5343 @cindex little-endian output, ARC
5345 @itemx -mlittle-endian
5346 Any @sc{arc} configuration of @code{@value{AS}} can select big-endian or
5347 little-endian output at run time (unlike most other @sc{gnu} development
5348 tools, which must be configured for one or the other). Use
5349 @samp{-mbig-endian} to select big-endian output, and @samp{-mlittle-endian}
5354 @section Floating Point
5356 @cindex floating point, ARC (@sc{ieee})
5357 @cindex ARC floating point (@sc{ieee})
5358 The ARC cpu family currently does not have hardware floating point
5359 support. Software floating point support is provided by @code{GCC}
5360 and uses @sc{ieee} floating-point numbers.
5362 @node ARC-Directives
5363 @section ARC Machine Directives
5365 @cindex ARC machine directives
5366 @cindex machine directives, ARC
5367 The ARC version of @code{@value{AS}} supports the following additional
5372 @cindex @code{cpu} directive, SPARC
5373 This must be followed by the desired cpu.
5374 The ARC is intended to be customizable, @code{.cpu} is used to
5375 select the desired variant [though currently there are none].
5382 @include c-a29k.texi
5391 @node Machine Dependencies
5392 @chapter Machine Dependent Features
5394 The machine instruction sets are different on each Hitachi chip family,
5395 and there are also some syntax differences among the families. This
5396 chapter describes the specific @code{@value{AS}} features for each
5400 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5401 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5402 * SH-Dependent:: Hitachi SH Dependent Features
5409 @include c-d10v.texi
5413 @include c-d30v.texi
5417 @include c-h8300.texi
5421 @include c-h8500.texi
5425 @include c-hppa.texi
5429 @include c-i370.texi
5433 @include c-i386.texi
5437 @include c-i860.texi
5441 @include c-i960.texi
5445 @include c-m32r.texi
5449 @include c-m68k.texi
5453 @include c-m68hc11.texi
5457 @include c-mips.texi
5461 @include c-ns32k.texi
5473 @include c-sparc.texi
5477 @include c-tic54x.texi
5489 @include c-v850.texi
5493 @c reverse effect of @down at top of generic Machine-Dep chapter
5497 @node Reporting Bugs
5498 @chapter Reporting Bugs
5499 @cindex bugs in assembler
5500 @cindex reporting bugs in assembler
5502 Your bug reports play an essential role in making @code{@value{AS}} reliable.
5504 Reporting a bug may help you by bringing a solution to your problem, or it may
5505 not. But in any case the principal function of a bug report is to help the
5506 entire community by making the next version of @code{@value{AS}} work better.
5507 Bug reports are your contribution to the maintenance of @code{@value{AS}}.
5509 In order for a bug report to serve its purpose, you must include the
5510 information that enables us to fix the bug.
5513 * Bug Criteria:: Have you found a bug?
5514 * Bug Reporting:: How to report bugs
5518 @section Have you found a bug?
5519 @cindex bug criteria
5521 If you are not sure whether you have found a bug, here are some guidelines:
5524 @cindex fatal signal
5525 @cindex assembler crash
5526 @cindex crash of assembler
5528 If the assembler gets a fatal signal, for any input whatever, that is a
5529 @code{@value{AS}} bug. Reliable assemblers never crash.
5531 @cindex error on valid input
5533 If @code{@value{AS}} produces an error message for valid input, that is a bug.
5535 @cindex invalid input
5537 If @code{@value{AS}} does not produce an error message for invalid input, that
5538 is a bug. However, you should note that your idea of ``invalid input'' might
5539 be our idea of ``an extension'' or ``support for traditional practice''.
5542 If you are an experienced user of assemblers, your suggestions for improvement
5543 of @code{@value{AS}} are welcome in any case.
5547 @section How to report bugs
5549 @cindex assembler bugs, reporting
5551 A number of companies and individuals offer support for @sc{gnu} products. If
5552 you obtained @code{@value{AS}} from a support organization, we recommend you
5553 contact that organization first.
5555 You can find contact information for many support companies and
5556 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5559 In any event, we also recommend that you send bug reports for @code{@value{AS}}
5560 to @samp{bug-gnu-utils@@gnu.org}.
5562 The fundamental principle of reporting bugs usefully is this:
5563 @strong{report all the facts}. If you are not sure whether to state a
5564 fact or leave it out, state it!
5566 Often people omit facts because they think they know what causes the problem
5567 and assume that some details do not matter. Thus, you might assume that the
5568 name of a symbol you use in an example does not matter. Well, probably it does
5569 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5570 happens to fetch from the location where that name is stored in memory;
5571 perhaps, if the name were different, the contents of that location would fool
5572 the assembler into doing the right thing despite the bug. Play it safe and
5573 give a specific, complete example. That is the easiest thing for you to do,
5574 and the most helpful.
5576 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5577 it is new to us. Therefore, always write your bug reports on the assumption
5578 that the bug has not been reported previously.
5580 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5581 bell?'' Those bug reports are useless, and we urge everyone to
5582 @emph{refuse to respond to them} except to chide the sender to report
5585 To enable us to fix the bug, you should include all these things:
5589 The version of @code{@value{AS}}. @code{@value{AS}} announces it if you start
5590 it with the @samp{--version} argument.
5592 Without this, we will not know whether there is any point in looking for
5593 the bug in the current version of @code{@value{AS}}.
5596 Any patches you may have applied to the @code{@value{AS}} source.
5599 The type of machine you are using, and the operating system name and
5603 What compiler (and its version) was used to compile @code{@value{AS}}---e.g.
5607 The command arguments you gave the assembler to assemble your example and
5608 observe the bug. To guarantee you will not omit something important, list them
5609 all. A copy of the Makefile (or the output from make) is sufficient.
5611 If we were to try to guess the arguments, we would probably guess wrong
5612 and then we might not encounter the bug.
5615 A complete input file that will reproduce the bug. If the bug is observed when
5616 the assembler is invoked via a compiler, send the assembler source, not the
5617 high level language source. Most compilers will produce the assembler source
5618 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5619 the options @samp{-v --save-temps}; this will save the assembler source in a
5620 file with an extension of @file{.s}, and also show you exactly how
5621 @code{@value{AS}} is being run.
5624 A description of what behavior you observe that you believe is
5625 incorrect. For example, ``It gets a fatal signal.''
5627 Of course, if the bug is that @code{@value{AS}} gets a fatal signal, then we
5628 will certainly notice it. But if the bug is incorrect output, we might not
5629 notice unless it is glaringly wrong. You might as well not give us a chance to
5632 Even if the problem you experience is a fatal signal, you should still say so
5633 explicitly. Suppose something strange is going on, such as, your copy of
5634 @code{@value{AS}} is out of synch, or you have encountered a bug in the C
5635 library on your system. (This has happened!) Your copy might crash and ours
5636 would not. If you told us to expect a crash, then when ours fails to crash, we
5637 would know that the bug was not happening for us. If you had not told us to
5638 expect a crash, then we would not be able to draw any conclusion from our
5642 If you wish to suggest changes to the @code{@value{AS}} source, send us context
5643 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
5644 option. Always send diffs from the old file to the new file. If you even
5645 discuss something in the @code{@value{AS}} source, refer to it by context, not
5648 The line numbers in our development sources will not match those in your
5649 sources. Your line numbers would convey no useful information to us.
5652 Here are some things that are not necessary:
5656 A description of the envelope of the bug.
5658 Often people who encounter a bug spend a lot of time investigating
5659 which changes to the input file will make the bug go away and which
5660 changes will not affect it.
5662 This is often time consuming and not very useful, because the way we
5663 will find the bug is by running a single example under the debugger
5664 with breakpoints, not by pure deduction from a series of examples.
5665 We recommend that you save your time for something else.
5667 Of course, if you can find a simpler example to report @emph{instead}
5668 of the original one, that is a convenience for us. Errors in the
5669 output will be easier to spot, running under the debugger will take
5670 less time, and so on.
5672 However, simplification is not vital; if you do not want to do this,
5673 report the bug anyway and send us the entire test case you used.
5676 A patch for the bug.
5678 A patch for the bug does help us if it is a good one. But do not omit
5679 the necessary information, such as the test case, on the assumption that
5680 a patch is all we need. We might see problems with your patch and decide
5681 to fix the problem another way, or we might not understand it at all.
5683 Sometimes with a program as complicated as @code{@value{AS}} it is very hard to
5684 construct an example that will make the program follow a certain path through
5685 the code. If you do not send us the example, we will not be able to construct
5686 one, so we will not be able to verify that the bug is fixed.
5688 And if we cannot understand what bug you are trying to fix, or why your
5689 patch should be an improvement, we will not install it. A test case will
5690 help us to understand.
5693 A guess about what the bug is or what it depends on.
5695 Such guesses are usually wrong. Even we cannot guess right about such
5696 things without first using the debugger to find the facts.
5699 @node Acknowledgements
5700 @chapter Acknowledgements
5702 If you have contributed to @code{@value{AS}} and your name isn't listed here,
5703 it is not meant as a slight. We just don't know about it. Send mail to the
5704 maintainer, and we'll correct the situation. Currently
5706 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
5708 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
5711 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
5712 information and the 68k series machines, most of the preprocessing pass, and
5713 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
5715 K. Richard Pixley maintained GAS for a while, adding various enhancements and
5716 many bug fixes, including merging support for several processors, breaking GAS
5717 up to handle multiple object file format back ends (including heavy rewrite,
5718 testing, an integration of the coff and b.out back ends), adding configuration
5719 including heavy testing and verification of cross assemblers and file splits
5720 and renaming, converted GAS to strictly ANSI C including full prototypes, added
5721 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
5722 port (including considerable amounts of reverse engineering), a SPARC opcode
5723 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
5724 assertions and made them work, much other reorganization, cleanup, and lint.
5726 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
5727 in format-specific I/O modules.
5729 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
5730 has done much work with it since.
5732 The Intel 80386 machine description was written by Eliot Dresselhaus.
5734 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
5736 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
5737 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
5739 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
5740 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
5741 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
5742 support a.out format.
5744 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
5745 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
5746 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
5747 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
5750 John Gilmore built the AMD 29000 support, added @code{.include} support, and
5751 simplified the configuration of which versions accept which directives. He
5752 updated the 68k machine description so that Motorola's opcodes always produced
5753 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
5754 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
5755 cross-compilation support, and one bug in relaxation that took a week and
5756 required the proverbial one-bit fix.
5758 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
5759 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
5760 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
5761 PowerPC assembler, and made a few other minor patches.
5763 Steve Chamberlain made @code{@value{AS}} able to generate listings.
5765 Hewlett-Packard contributed support for the HP9000/300.
5767 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
5768 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
5769 formats). This work was supported by both the Center for Software Science at
5770 the University of Utah and Cygnus Support.
5772 Support for ELF format files has been worked on by Mark Eichin of Cygnus
5773 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
5774 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
5775 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
5776 and some initial 64-bit support).
5778 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
5780 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
5781 support for openVMS/Alpha.
5783 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
5786 Several engineers at Cygnus Support have also provided many small bug fixes and
5787 configuration enhancements.
5789 Many others have contributed large or small bugfixes and enhancements. If
5790 you have contributed significant work and are not mentioned on this list, and
5791 want to be, let us know. Some of the history has been lost; we are not
5792 intentionally leaving anyone out.
5794 @node GNU Free Documentation License
5795 @chapter GNU Free Documentation License
5797 GNU Free Documentation License
5799 Version 1.1, March 2000
5801 Copyright (C) 2000 Free Software Foundation, Inc.
5802 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
5804 Everyone is permitted to copy and distribute verbatim copies
5805 of this license document, but changing it is not allowed.
5810 The purpose of this License is to make a manual, textbook, or other
5811 written document "free" in the sense of freedom: to assure everyone
5812 the effective freedom to copy and redistribute it, with or without
5813 modifying it, either commercially or noncommercially. Secondarily,
5814 this License preserves for the author and publisher a way to get
5815 credit for their work, while not being considered responsible for
5816 modifications made by others.
5818 This License is a kind of "copyleft", which means that derivative
5819 works of the document must themselves be free in the same sense. It
5820 complements the GNU General Public License, which is a copyleft
5821 license designed for free software.
5823 We have designed this License in order to use it for manuals for free
5824 software, because free software needs free documentation: a free
5825 program should come with manuals providing the same freedoms that the
5826 software does. But this License is not limited to software manuals;
5827 it can be used for any textual work, regardless of subject matter or
5828 whether it is published as a printed book. We recommend this License
5829 principally for works whose purpose is instruction or reference.
5832 1. APPLICABILITY AND DEFINITIONS
5834 This License applies to any manual or other work that contains a
5835 notice placed by the copyright holder saying it can be distributed
5836 under the terms of this License. The "Document", below, refers to any
5837 such manual or work. Any member of the public is a licensee, and is
5840 A "Modified Version" of the Document means any work containing the
5841 Document or a portion of it, either copied verbatim, or with
5842 modifications and/or translated into another language.
5844 A "Secondary Section" is a named appendix or a front-matter section of
5845 the Document that deals exclusively with the relationship of the
5846 publishers or authors of the Document to the Document's overall subject
5847 (or to related matters) and contains nothing that could fall directly
5848 within that overall subject. (For example, if the Document is in part a
5849 textbook of mathematics, a Secondary Section may not explain any
5850 mathematics.) The relationship could be a matter of historical
5851 connection with the subject or with related matters, or of legal,
5852 commercial, philosophical, ethical or political position regarding
5855 The "Invariant Sections" are certain Secondary Sections whose titles
5856 are designated, as being those of Invariant Sections, in the notice
5857 that says that the Document is released under this License.
5859 The "Cover Texts" are certain short passages of text that are listed,
5860 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
5861 the Document is released under this License.
5863 A "Transparent" copy of the Document means a machine-readable copy,
5864 represented in a format whose specification is available to the
5865 general public, whose contents can be viewed and edited directly and
5866 straightforwardly with generic text editors or (for images composed of
5867 pixels) generic paint programs or (for drawings) some widely available
5868 drawing editor, and that is suitable for input to text formatters or
5869 for automatic translation to a variety of formats suitable for input
5870 to text formatters. A copy made in an otherwise Transparent file
5871 format whose markup has been designed to thwart or discourage
5872 subsequent modification by readers is not Transparent. A copy that is
5873 not "Transparent" is called "Opaque".
5875 Examples of suitable formats for Transparent copies include plain
5876 ASCII without markup, Texinfo input format, LaTeX input format, SGML
5877 or XML using a publicly available DTD, and standard-conforming simple
5878 HTML designed for human modification. Opaque formats include
5879 PostScript, PDF, proprietary formats that can be read and edited only
5880 by proprietary word processors, SGML or XML for which the DTD and/or
5881 processing tools are not generally available, and the
5882 machine-generated HTML produced by some word processors for output
5885 The "Title Page" means, for a printed book, the title page itself,
5886 plus such following pages as are needed to hold, legibly, the material
5887 this License requires to appear in the title page. For works in
5888 formats which do not have any title page as such, "Title Page" means
5889 the text near the most prominent appearance of the work's title,
5890 preceding the beginning of the body of the text.
5895 You may copy and distribute the Document in any medium, either
5896 commercially or noncommercially, provided that this License, the
5897 copyright notices, and the license notice saying this License applies
5898 to the Document are reproduced in all copies, and that you add no other
5899 conditions whatsoever to those of this License. You may not use
5900 technical measures to obstruct or control the reading or further
5901 copying of the copies you make or distribute. However, you may accept
5902 compensation in exchange for copies. If you distribute a large enough
5903 number of copies you must also follow the conditions in section 3.
5905 You may also lend copies, under the same conditions stated above, and
5906 you may publicly display copies.
5909 3. COPYING IN QUANTITY
5911 If you publish printed copies of the Document numbering more than 100,
5912 and the Document's license notice requires Cover Texts, you must enclose
5913 the copies in covers that carry, clearly and legibly, all these Cover
5914 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
5915 the back cover. Both covers must also clearly and legibly identify
5916 you as the publisher of these copies. The front cover must present
5917 the full title with all words of the title equally prominent and
5918 visible. You may add other material on the covers in addition.
5919 Copying with changes limited to the covers, as long as they preserve
5920 the title of the Document and satisfy these conditions, can be treated
5921 as verbatim copying in other respects.
5923 If the required texts for either cover are too voluminous to fit
5924 legibly, you should put the first ones listed (as many as fit
5925 reasonably) on the actual cover, and continue the rest onto adjacent
5928 If you publish or distribute Opaque copies of the Document numbering
5929 more than 100, you must either include a machine-readable Transparent
5930 copy along with each Opaque copy, or state in or with each Opaque copy
5931 a publicly-accessible computer-network location containing a complete
5932 Transparent copy of the Document, free of added material, which the
5933 general network-using public has access to download anonymously at no
5934 charge using public-standard network protocols. If you use the latter
5935 option, you must take reasonably prudent steps, when you begin
5936 distribution of Opaque copies in quantity, to ensure that this
5937 Transparent copy will remain thus accessible at the stated location
5938 until at least one year after the last time you distribute an Opaque
5939 copy (directly or through your agents or retailers) of that edition to
5942 It is requested, but not required, that you contact the authors of the
5943 Document well before redistributing any large number of copies, to give
5944 them a chance to provide you with an updated version of the Document.
5949 You may copy and distribute a Modified Version of the Document under
5950 the conditions of sections 2 and 3 above, provided that you release
5951 the Modified Version under precisely this License, with the Modified
5952 Version filling the role of the Document, thus licensing distribution
5953 and modification of the Modified Version to whoever possesses a copy
5954 of it. In addition, you must do these things in the Modified Version:
5956 A. Use in the Title Page (and on the covers, if any) a title distinct
5957 from that of the Document, and from those of previous versions
5958 (which should, if there were any, be listed in the History section
5959 of the Document). You may use the same title as a previous version
5960 if the original publisher of that version gives permission.
5961 B. List on the Title Page, as authors, one or more persons or entities
5962 responsible for authorship of the modifications in the Modified
5963 Version, together with at least five of the principal authors of the
5964 Document (all of its principal authors, if it has less than five).
5965 C. State on the Title page the name of the publisher of the
5966 Modified Version, as the publisher.
5967 D. Preserve all the copyright notices of the Document.
5968 E. Add an appropriate copyright notice for your modifications
5969 adjacent to the other copyright notices.
5970 F. Include, immediately after the copyright notices, a license notice
5971 giving the public permission to use the Modified Version under the
5972 terms of this License, in the form shown in the Addendum below.
5973 G. Preserve in that license notice the full lists of Invariant Sections
5974 and required Cover Texts given in the Document's license notice.
5975 H. Include an unaltered copy of this License.
5976 I. Preserve the section entitled "History", and its title, and add to
5977 it an item stating at least the title, year, new authors, and
5978 publisher of the Modified Version as given on the Title Page. If
5979 there is no section entitled "History" in the Document, create one
5980 stating the title, year, authors, and publisher of the Document as
5981 given on its Title Page, then add an item describing the Modified
5982 Version as stated in the previous sentence.
5983 J. Preserve the network location, if any, given in the Document for
5984 public access to a Transparent copy of the Document, and likewise
5985 the network locations given in the Document for previous versions
5986 it was based on. These may be placed in the "History" section.
5987 You may omit a network location for a work that was published at
5988 least four years before the Document itself, or if the original
5989 publisher of the version it refers to gives permission.
5990 K. In any section entitled "Acknowledgements" or "Dedications",
5991 preserve the section's title, and preserve in the section all the
5992 substance and tone of each of the contributor acknowledgements
5993 and/or dedications given therein.
5994 L. Preserve all the Invariant Sections of the Document,
5995 unaltered in their text and in their titles. Section numbers
5996 or the equivalent are not considered part of the section titles.
5997 M. Delete any section entitled "Endorsements". Such a section
5998 may not be included in the Modified Version.
5999 N. Do not retitle any existing section as "Endorsements"
6000 or to conflict in title with any Invariant Section.
6002 If the Modified Version includes new front-matter sections or
6003 appendices that qualify as Secondary Sections and contain no material
6004 copied from the Document, you may at your option designate some or all
6005 of these sections as invariant. To do this, add their titles to the
6006 list of Invariant Sections in the Modified Version's license notice.
6007 These titles must be distinct from any other section titles.
6009 You may add a section entitled "Endorsements", provided it contains
6010 nothing but endorsements of your Modified Version by various
6011 parties--for example, statements of peer review or that the text has
6012 been approved by an organization as the authoritative definition of a
6015 You may add a passage of up to five words as a Front-Cover Text, and a
6016 passage of up to 25 words as a Back-Cover Text, to the end of the list
6017 of Cover Texts in the Modified Version. Only one passage of
6018 Front-Cover Text and one of Back-Cover Text may be added by (or
6019 through arrangements made by) any one entity. If the Document already
6020 includes a cover text for the same cover, previously added by you or
6021 by arrangement made by the same entity you are acting on behalf of,
6022 you may not add another; but you may replace the old one, on explicit
6023 permission from the previous publisher that added the old one.
6025 The author(s) and publisher(s) of the Document do not by this License
6026 give permission to use their names for publicity for or to assert or
6027 imply endorsement of any Modified Version.
6030 5. COMBINING DOCUMENTS
6032 You may combine the Document with other documents released under this
6033 License, under the terms defined in section 4 above for modified
6034 versions, provided that you include in the combination all of the
6035 Invariant Sections of all of the original documents, unmodified, and
6036 list them all as Invariant Sections of your combined work in its
6039 The combined work need only contain one copy of this License, and
6040 multiple identical Invariant Sections may be replaced with a single
6041 copy. If there are multiple Invariant Sections with the same name but
6042 different contents, make the title of each such section unique by
6043 adding at the end of it, in parentheses, the name of the original
6044 author or publisher of that section if known, or else a unique number.
6045 Make the same adjustment to the section titles in the list of
6046 Invariant Sections in the license notice of the combined work.
6048 In the combination, you must combine any sections entitled "History"
6049 in the various original documents, forming one section entitled
6050 "History"; likewise combine any sections entitled "Acknowledgements",
6051 and any sections entitled "Dedications". You must delete all sections
6052 entitled "Endorsements."
6055 6. COLLECTIONS OF DOCUMENTS
6057 You may make a collection consisting of the Document and other documents
6058 released under this License, and replace the individual copies of this
6059 License in the various documents with a single copy that is included in
6060 the collection, provided that you follow the rules of this License for
6061 verbatim copying of each of the documents in all other respects.
6063 You may extract a single document from such a collection, and distribute
6064 it individually under this License, provided you insert a copy of this
6065 License into the extracted document, and follow this License in all
6066 other respects regarding verbatim copying of that document.
6069 7. AGGREGATION WITH INDEPENDENT WORKS
6071 A compilation of the Document or its derivatives with other separate
6072 and independent documents or works, in or on a volume of a storage or
6073 distribution medium, does not as a whole count as a Modified Version
6074 of the Document, provided no compilation copyright is claimed for the
6075 compilation. Such a compilation is called an "aggregate", and this
6076 License does not apply to the other self-contained works thus compiled
6077 with the Document, on account of their being thus compiled, if they
6078 are not themselves derivative works of the Document.
6080 If the Cover Text requirement of section 3 is applicable to these
6081 copies of the Document, then if the Document is less than one quarter
6082 of the entire aggregate, the Document's Cover Texts may be placed on
6083 covers that surround only the Document within the aggregate.
6084 Otherwise they must appear on covers around the whole aggregate.
6089 Translation is considered a kind of modification, so you may
6090 distribute translations of the Document under the terms of section 4.
6091 Replacing Invariant Sections with translations requires special
6092 permission from their copyright holders, but you may include
6093 translations of some or all Invariant Sections in addition to the
6094 original versions of these Invariant Sections. You may include a
6095 translation of this License provided that you also include the
6096 original English version of this License. In case of a disagreement
6097 between the translation and the original English version of this
6098 License, the original English version will prevail.
6103 You may not copy, modify, sublicense, or distribute the Document except
6104 as expressly provided for under this License. Any other attempt to
6105 copy, modify, sublicense or distribute the Document is void, and will
6106 automatically terminate your rights under this License. However,
6107 parties who have received copies, or rights, from you under this
6108 License will not have their licenses terminated so long as such
6109 parties remain in full compliance.
6112 10. FUTURE REVISIONS OF THIS LICENSE
6114 The Free Software Foundation may publish new, revised versions
6115 of the GNU Free Documentation License from time to time. Such new
6116 versions will be similar in spirit to the present version, but may
6117 differ in detail to address new problems or concerns. See
6118 http://www.gnu.org/copyleft/.
6120 Each version of the License is given a distinguishing version number.
6121 If the Document specifies that a particular numbered version of this
6122 License "or any later version" applies to it, you have the option of
6123 following the terms and conditions either of that specified version or
6124 of any later version that has been published (not as a draft) by the
6125 Free Software Foundation. If the Document does not specify a version
6126 number of this License, you may choose any version ever published (not
6127 as a draft) by the Free Software Foundation.
6130 ADDENDUM: How to use this License for your documents
6132 To use this License in a document you have written, include a copy of
6133 the License in the document and put the following copyright and
6134 license notices just after the title page:
6137 Copyright (c) YEAR YOUR NAME.
6138 Permission is granted to copy, distribute and/or modify this document
6139 under the terms of the GNU Free Documentation License, Version 1.1
6140 or any later version published by the Free Software Foundation;
6141 with the Invariant Sections being LIST THEIR TITLES, with the
6142 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6143 A copy of the license is included in the section entitled "GNU
6144 Free Documentation License".
6147 If you have no Invariant Sections, write "with no Invariant Sections"
6148 instead of saying which ones are invariant. If you have no
6149 Front-Cover Texts, write "no Front-Cover Texts" instead of
6150 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6152 If your document contains nontrivial examples of program code, we
6153 recommend releasing these examples in parallel under your choice of
6154 free software license, such as the GNU General Public License,
6155 to permit their use in free software.
projects / external / binutils.git / blob