AS(1) GNU Development Tools AS(1)NAMEAS - the portable GNU assembler.
SYNOPSIS
as [-a[cdhlns][=file]] [--alternate] [-D]
[--defsym sym=val] [-f] [-g] [--gstabs]
[--gstabs+] [--gdwarf-2] [--help] [-I dir] [-J]
[-K] [-L] [--listing-lhs-width=NUM]
[--listing-lhs-width2=NUM] [--listing-rhs-width=NUM]
[--listing-cont-lines=NUM] [--keep-locals] [-o
objfile] [-R] [--reduce-memory-overheads] [--statistics]
[-v] [-version] [--version] [-W] [--warn]
[--fatal-warnings] [-w] [-x] [-Z] [--target-help]
[target-options] [--|files ...]
Target Alpha options:
[-mcpu]
[-mdebug | -no-mdebug]
[-relax] [-g] [-Gsize]
[-F] [-32addr]
Target ARC options:
[-marc[5|6|7|8]]
[-EB|-EL]
Target ARM options:
[-mcpu=processor[+extension...]]
[-march=architecture[+extension...]]
[-mfpu=floating-point-format]
[-mfloat-abi=abi]
[-meabi=ver]
[-mthumb]
[-EB|-EL]
[-mapcs-32|-mapcs-26|-mapcs-float|
-mapcs-reentrant]
[-mthumb-interwork] [-k]
Target CRIS options:
[--underscore | --no-underscore]
[--pic] [-N]
[--emulation=criself | --emulation=crisaout]
[--march=v0_v10 | --march=v10 | --march=v32 |
--march=common_v10_v32]
Target D10V options:
[-O]
Target D30V options:
[-O|-n|-N]
Target i386 options:
[--32|--64] [-n]
binutils-050707 2011-08-18 1
AS(1) GNU Development Tools AS(1)
Target i960 options:
[-ACA|-ACA_A|-ACB|-ACC|-AKA|-AKB|
-AKC|-AMC]
[-b] [-no-relax]
Target IA-64 options:
[-mconstant-gp|-mauto-pic]
[-milp32|-milp64|-mlp64|-mp64]
[-mle|mbe]
[-mtune=itanium1|-mtune=itanium2]
[-munwind-check=warning|-munwind-check=error]
[-mhint.b=ok|-mhint.b=warning|-mhint.b=error]
[-x|-xexplicit] [-xauto] [-xdebug]
Target IP2K options:
[-mip2022|-mip2022ext]
Target M32R options:
[--m32rx|--[no-]warn-explicit-parallel-conflicts|
--W[n]p]
Target M680X0 options:
[-l] [-m68000|-m68010|-m68020|...]
Target M68HC11 options:
[-m68hc11|-m68hc12|-m68hcs12]
[-mshort|-mlong]
[-mshort-double|-mlong-double]
[--force-long-branchs] [--short-branchs]
[--strict-direct-mode] [--print-insn-syntax]
[--print-opcodes] [--generate-example]
Target MCORE options:
[-jsri2bsr] [-sifilter] [-relax]
[-mcpu=[210|340]]
Target MIPS options:
[-nocpp] [-EL] [-EB] [-O[optimization level]]
[-g[debug level]] [-G num] [-KPIC] [-call_shared]
[-non_shared] [-xgot]
[-mabi=ABI] [-32] [-n32] [-64] [-mfp32] [-mgp32]
[-march=CPU] [-mtune=CPU] [-mips1] [-mips2]
[-mips3] [-mips4] [-mips5] [-mips32] [-mips32r2]
[-mips64] [-mips64r2]
[-construct-floats] [-no-construct-floats]
[-trap] [-no-break] [-break] [-no-trap]
[-mfix7000] [-mno-fix7000]
[-mips16] [-no-mips16]
[-mips3d] [-no-mips3d]
[-mdmx] [-no-mdmx]
[-mdebug] [-no-mdebug]
[-mpdr] [-mno-pdr]
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AS(1) GNU Development Tools AS(1)
Target MMIX options:
[--fixed-special-register-names] [--globalize-symbols]
[--gnu-syntax] [--relax] [--no-predefined-symbols]
[--no-expand] [--no-merge-gregs] [-x]
[--linker-allocated-gregs]
Target PDP11 options:
[-mpic|-mno-pic] [-mall] [-mno-extensions]
[-mextension|-mno-extension]
[-mcpu] [-mmachine]
Target picoJava options:
[-mb|-me]
Target PowerPC options:
[-mpwrx|-mpwr2|-mpwr|-m601|-mppc|-mppc32|-m603|-m604|
-m403|-m405|-mppc64|-m620|-mppc64bridge|-mbooke|
-mbooke32|-mbooke64]
[-mcom|-many|-maltivec] [-memb]
[-mregnames|-mno-regnames]
[-mrelocatable|-mrelocatable-lib]
[-mlittle|-mlittle-endian|-mbig|-mbig-endian]
[-msolaris|-mno-solaris]
Target SPARC options:
[-Av6|-Av7|-Av8|-Asparclet|-Asparclite
-Av8plus|-Av8plusa|-Av9|-Av9a]
[-xarch=v8plus|-xarch=v8plusa] [-bump]
[-32|-64]
Target TIC54X options:
[-mcpu=54[123589]|-mcpu=54[56]lp] [-mfar-mode|-mf]
[-merrors-to-file <filename>|-me <filename>]
Target Xtensa options:
[--[no-]text-section-literals] [--[no-]absolute-literals]
[--[no-]target-align] [--[no-]longcalls]
[--[no-]transform]
[--rename-section oldname=newname]
DESCRIPTION
GNU as is really a family of assemblers. If you use (or have
used) the GNU assembler on one architecture, you should find
a fairly similar environment when you use it on another
architecture. Each version has much in common with the oth-
ers, including object file formats, most assembler direc-
tives (often called pseudo-ops) and assembler syntax.
as is primarily intended to assemble the output of the GNU C
compiler "gcc" for use by the linker "ld". Nevertheless,
we've tried to make as assemble correctly everything that
other assemblers for the same machine would assemble. Any
binutils-050707 2011-08-18 3
AS(1) GNU Development Tools AS(1)
exceptions are documented explicitly. This doesn't mean as
always uses the same syntax as another assembler for the
same architecture; for example, we know of several incompa-
tible versions of 680x0 assembly language syntax.
Each time you run as it assembles exactly one source pro-
gram. The source program is made up of one or more files.
(The standard input is also a file.)
You give as a command line that has zero or more input file
names. The input files are read (from left file name to
right). A command line argument (in any position) that has
no special meaning is taken to be an input file name.
If you give as no file names it attempts to read one input
file from the as standard input, which is normally your ter-
minal. You may have to type ctl-D to tell as there is no
more program to assemble.
Use -- if you need to explicitly name the standard input
file in your command line.
If the source is empty, as produces a small, empty object
file.
as may write warnings and error messages to the standard
error file (usually your terminal). This should not happen
when a compiler runs as automatically. Warnings report an
assumption made so that as could keep assembling a flawed
program; errors report a grave problem that stops the assem-
bly.
If you are invoking as via the GNU C compiler, you can use
the -Wa option to pass arguments through to the assembler.
The assembler arguments must be separated from each other
(and the -Wa) by commas. For example:
gcc -c -g -O -Wa,-alh,-L file.c
This passes two options to the assembler: -alh (emit a list-
ing to standard output with high-level and assembly source)
and -L (retain local symbols in the symbol table).
Usually you do not need to use this -Wa mechanism, since
many compiler command-line options are automatically passed
to the assembler by the compiler. (You can call the GNU com-
piler driver with the -v option to see precisely what
options it passes to each compilation pass, including the
assembler.)
OPTIONS
-a[cdhlmns]
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AS(1) GNU Development Tools AS(1)
Turn on listings, in any of a variety of ways:
-ac omit false conditionals
-ad omit debugging directives
-ah include high-level source
-al include assembly
-am include macro expansions
-an omit forms processing
-as include symbols
=file
set the name of the listing file
You may combine these options; for example, use -aln for
assembly listing without forms processing. The =file
option, if used, must be the last one. By itself, -a
defaults to -ahls.
--alternate
Begin in alternate macro mode, see
@ref{Altmacro,,".altmacro"}.
-D Ignored. This option is accepted for script compatibil-
ity with calls to other assemblers.
--defsym sym=value
Define the symbol sym to be value before assembling the
input file. value must be an integer constant. As in C,
a leading 0x indicates a hexadecimal value, and a lead-
ing 0 indicates an octal value.
-f ``fast''---skip whitespace and comment preprocessing
(assume source is compiler output).
-g
--gen-debug
Generate debugging information for each assembler source
line using whichever debug format is preferred by the
target. This currently means either STABS, ECOFF or
DWARF2.
--gstabs
Generate stabs debugging information for each assembler
line. This may help debugging assembler code, if the
debugger can handle it.
binutils-050707 2011-08-18 5
AS(1) GNU Development Tools AS(1)
--gstabs+
Generate stabs debugging information for each assembler
line, with GNU extensions that probably only gdb can
handle, and that could make other debuggers crash or
refuse to read your program. This may help debugging
assembler code. Currently the only GNU extension is the
location of the current working directory at assembling
time.
--gdwarf-2
Generate DWARF2 debugging information for each assembler
line. This may help debugging assembler code, if the
debugger can handle it. Note---this option is only sup-
ported by some targets, not all of them.
--help
Print a summary of the command line options and exit.
--target-help
Print a summary of all target specific options and exit.
-I dir
Add directory dir to the search list for ".include"
directives.
-J Don't warn about signed overflow.
-K Issue warnings when difference tables altered for long
displacements.
-L
--keep-locals
Keep (in the symbol table) local symbols. On tradi-
tional a.out systems these start with L, but different
systems have different local label prefixes.
--listing-lhs-width=number
Set the maximum width, in words, of the output data
column for an assembler listing to number.
--listing-lhs-width2=number
Set the maximum width, in words, of the output data
column for continuation lines in an assembler listing to
number.
--listing-rhs-width=number
Set the maximum width of an input source line, as
displayed in a listing, to number bytes.
--listing-cont-lines=number
Set the maximum number of lines printed in a listing for
a single line of input to number + 1.
binutils-050707 2011-08-18 6
AS(1) GNU Development Tools AS(1)-o objfile
Name the object-file output from as objfile.
-R Fold the data section into the text section.
Set the default size of GAS's hash tables to a prime
number close to number. Increasing this value can
reduce the length of time it takes the assembler to per-
form its tasks, at the expense of increasing the
assembler's memory requirements. Similarly reducing
this value can reduce the memory requirements at the
expense of speed.
--reduce-memory-overheads
This option reduces GAS's memory requirements, at the
expense of making the assembly processes slower.
Currently this switch is a synonym for --hash-size=4051,
but in the future it may have other effects as well.
--statistics
Print the maximum space (in bytes) and total time (in
seconds) used by assembly.
--strip-local-absolute
Remove local absolute symbols from the outgoing symbol
table.
-v
-version
Print the as version.
--version
Print the as version and exit.
-W
--no-warn
Suppress warning messages.
--fatal-warnings
Treat warnings as errors.
--warn
Don't suppress warning messages or treat them as errors.
-w Ignored.
-x Ignored.
-Z Generate an object file even after errors.
-- | files ...
Standard input, or source files to assemble.
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AS(1) GNU Development Tools AS(1)
The following options are available when as is configured
for an ARC processor.
-marc[5|6|7|8]
This option selects the core processor variant.
-EB | -EL
Select either big-endian (-EB) or little-endian (-EL)
output.
The following options are available when as is configured
for the ARM processor family.
-mcpu=processor[+extension...]
Specify which ARM processor variant is the target.
-march=architecture[+extension...]
Specify which ARM architecture variant is used by the
target.
-mfpu=floating-point-format
Select which Floating Point architecture is the target.
-mfloat-abi=abi
Select which floating point ABI is in use.
-mthumb
Enable Thumb only instruction decoding.
-mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant
Select which procedure calling convention is in use.
-EB | -EL
Select either big-endian (-EB) or little-endian (-EL)
output.
-mthumb-interwork
Specify that the code has been generated with interwork-
ing between Thumb and ARM code in mind.
-k Specify that PIC code has been generated.
See the info pages for documentation of the CRIS-specific
options.
The following options are available when as is configured
for a D10V processor.
-O Optimize output by parallelizing instructions.
The following options are available when as is configured
for a D30V processor.
binutils-050707 2011-08-18 8
AS(1) GNU Development Tools AS(1)-O Optimize output by parallelizing instructions.
-n Warn when nops are generated.
-N Warn when a nop after a 32-bit multiply instruction is
generated.
The following options are available when as is configured
for the Intel 80960 processor.
-ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
Specify which variant of the 960 architecture is the
target.
-b Add code to collect statistics about branches taken.
-no-relax
Do not alter compare-and-branch instructions for long
displacements; error if necessary.
The following options are available when as is configured
for the Ubicom IP2K series.
-mip2022ext
Specifies that the extended IP2022 instructions are
allowed.
-mip2022
Restores the default behaviour, which restricts the per-
mitted instructions to just the basic IP2022 ones.
The following options are available when as is configured
for the Renesas M32R (formerly Mitsubishi M32R) series.
--m32rx
Specify which processor in the M32R family is the tar-
get. The default is normally the M32R, but this option
changes it to the M32RX.
--warn-explicit-parallel-conflicts or --Wp
Produce warning messages when questionable parallel con-
structs are encountered.
--no-warn-explicit-parallel-conflicts or --Wnp
Do not produce warning messages when questionable paral-
lel constructs are encountered.
The following options are available when as is configured
for the Motorola 68000 series.
-l Shorten references to undefined symbols, to one word
instead of two.
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AS(1) GNU Development Tools AS(1)-m68000 | -m68008 | -m68010 | -m68020 | -m68030
| -m68040 | -m68060 | -m68302 | -m68331 | -m68332
| -m68333 | -m68340 | -mcpu32 | -m5200
Specify what processor in the 68000 family is the tar-
get. The default is normally the 68020, but this can be
changed at configuration time.
-m68881 | -m68882 | -mno-68881 | -mno-68882
The target machine does (or does not) have a floating-
point coprocessor. The default is to assume a coproces-
sor for 68020, 68030, and cpu32. Although the basic
68000 is not compatible with the 68881, a combination of
the two can be specified, since it's possible to do emu-
lation of the coprocessor instructions with the main
processor.
-m68851 | -mno-68851
The target machine does (or does not) have a memory-
management unit coprocessor. The default is to assume
an MMU for 68020 and up.
For details about the PDP-11 machine dependent features
options, see @ref{PDP-11-Options}.
-mpic | -mno-pic
Generate position-independent (or position-dependent)
code. The default is -mpic.
-mall
-mall-extensions
Enable all instruction set extensions. This is the
default.
-mno-extensions
Disable all instruction set extensions.
-mextension | -mno-extension
Enable (or disable) a particular instruction set exten-
sion.
-mcpu
Enable the instruction set extensions supported by a
particular CPU, and disable all other extensions.
-mmachine
Enable the instruction set extensions supported by a
particular machine model, and disable all other exten-
sions.
The following options are available when as is configured
for a picoJava processor.
binutils-050707 2011-08-18 10
AS(1) GNU Development Tools AS(1)-mb Generate ``big endian'' format output.
-ml Generate ``little endian'' format output.
The following options are available when as is configured
for the Motorola 68HC11 or 68HC12 series.
-m68hc11 | -m68hc12 | -m68hcs12
Specify what processor is the target. The default is
defined by the configuration option when building the
assembler.
-mshort
Specify to use the 16-bit integer ABI.
-mlong
Specify to use the 32-bit integer ABI.
-mshort-double
Specify to use the 32-bit double ABI.
-mlong-double
Specify to use the 64-bit double ABI.
--force-long-branchs
Relative branches are turned into absolute ones. This
concerns conditional branches, unconditional branches
and branches to a sub routine.
-S | --short-branchs
Do not turn relative branchs into absolute ones when the
offset is out of range.
--strict-direct-mode
Do not turn the direct addressing mode into extended
addressing mode when the instruction does not support
direct addressing mode.
--print-insn-syntax
Print the syntax of instruction in case of error.
--print-opcodes
print the list of instructions with syntax and then
exit.
--generate-example
print an example of instruction for each possible
instruction and then exit. This option is only useful
for testing as.
The following options are available when as is configured
for the SPARC architecture:
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AS(1) GNU Development Tools AS(1)-Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
-Av8plus | -Av8plusa | -Av9 | -Av9a
Explicitly select a variant of the SPARC architecture.
-Av8plus and -Av8plusa select a 32 bit environment. -Av9
and -Av9a select a 64 bit environment.
-Av8plusa and -Av9a enable the SPARC V9 instruction set
with UltraSPARC extensions.
-xarch=v8plus | -xarch=v8plusa
For compatibility with the Solaris v9 assembler. These
options are equivalent to -Av8plus and -Av8plusa,
respectively.
-bump
Warn when the assembler switches to another architec-
ture.
The following options are available when as is configured
for the 'c54x architecture.
-mfar-mode
Enable extended addressing mode. All addresses and
relocations will assume extended addressing (usually 23
bits).
-mcpu=CPU_VERSION
Sets the CPU version being compiled for.
-merrors-to-file FILENAME
Redirect error output to a file, for broken systems
which don't support such behaviour in the shell.
The following options are available when as is configured
for a MIPS processor.
-G num
This option sets the largest size of an object that can
be referenced implicitly with the "gp" register. It is
only accepted for targets that use ECOFF format, such as
a DECstation running Ultrix. The default value is 8.
-EB Generate ``big endian'' format output.
-EL Generate ``little endian'' format output.
-mips1
-mips2
-mips3
-mips4
-mips5
binutils-050707 2011-08-18 12
AS(1) GNU Development Tools AS(1)-mips32
-mips32r2
-mips64
-mips64r2
Generate code for a particular MIPS Instruction Set
Architecture level. -mips1 is an alias for -march=r3000,
-mips2 is an alias for -march=r6000, -mips3 is an alias
for -march=r4000 and -mips4 is an alias for
-march=r8000. -mips5, -mips32, -mips32r2, -mips64, and
-mips64r2 correspond to generic MIPS V, MIPS32, MIPS32
Release 2, MIPS64, and MIPS64 Release 2 ISA processors,
respectively.
-march=CPU
Generate code for a particular MIPS cpu.
-mtune=cpu
Schedule and tune for a particular MIPS cpu.
-mfix7000
-mno-fix7000
Cause nops to be inserted if the read of the destination
register of an mfhi or mflo instruction occurs in the
following two instructions.
-mdebug
-no-mdebug
Cause stabs-style debugging output to go into an ECOFF-
style .mdebug section instead of the standard ELF .stabs
sections.
-mpdr
-mno-pdr
Control generation of ".pdr" sections.
-mgp32
-mfp32
The register sizes are normally inferred from the ISA
and ABI, but these flags force a certain group of regis-
ters to be treated as 32 bits wide at all times. -mgp32
controls the size of general-purpose registers and
-mfp32 controls the size of floating-point registers.
-mips16
-no-mips16
Generate code for the MIPS 16 processor. This is
equivalent to putting ".set mips16" at the start of the
assembly file. -no-mips16 turns off this option.
-mips3d
-no-mips3d
Generate code for the MIPS-3D Application Specific
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AS(1) GNU Development Tools AS(1)
Extension. This tells the assembler to accept MIPS-3D
instructions. -no-mips3d turns off this option.
-mdmx
-no-mdmx
Generate code for the MDMX Application Specific Exten-
sion. This tells the assembler to accept MDMX instruc-
tions. -no-mdmx turns off this option.
--construct-floats
--no-construct-floats
The --no-construct-floats option disables the construc-
tion of double width floating point constants by loading
the two halves of the value into the two single width
floating point registers that make up the double width
register. By default --construct-floats is selected,
allowing construction of these floating point constants.
--emulation=name
This option causes as to emulate as configured for some
other target, in all respects, including output format
(choosing between ELF and ECOFF only), handling of
pseudo-opcodes which may generate debugging information
or store symbol table information, and default endian-
ness. The available configuration names are: mipsecoff,
mipself, mipslecoff, mipsbecoff, mipslelf, mipsbelf.
The first two do not alter the default endianness from
that of the primary target for which the assembler was
configured; the others change the default to little- or
big-endian as indicated by the b or l in the name.
Using -EB or -EL will override the endianness selection
in any case.
This option is currently supported only when the primary
target as is configured for is a MIPS ELF or ECOFF tar-
get. Furthermore, the primary target or others specified
with --enable-targets=... at configuration time must
include support for the other format, if both are to be
available. For example, the Irix 5 configuration
includes support for both.
Eventually, this option will support more configura-
tions, with more fine-grained control over the
assembler's behavior, and will be supported for more
processors.
-nocpp
as ignores this option. It is accepted for compatibil-
ity with the native tools.
--trap
--no-trap
binutils-050707 2011-08-18 14
AS(1) GNU Development Tools AS(1)--break
--no-break
Control how to deal with multiplication overflow and
division by zero. --trap or --no-break (which are
synonyms) take a trap exception (and only work for
Instruction Set Architecture level 2 and higher);
--break or --no-trap (also synonyms, and the default)
take a break exception.
-n When this option is used, as will issue a warning every
time it generates a nop instruction from a macro.
The following options are available when as is configured
for an MCore processor.
-jsri2bsr
-nojsri2bsr
Enable or disable the JSRI to BSR transformation. By
default this is enabled. The command line option
-nojsri2bsr can be used to disable it.
-sifilter
-nosifilter
Enable or disable the silicon filter behaviour. By
default this is disabled. The default can be overridden
by the -sifilter command line option.
-relax
Alter jump instructions for long displacements.
-mcpu=[210|340]
Select the cpu type on the target hardware. This con-
trols which instructions can be assembled.
-EB Assemble for a big endian target.
-EL Assemble for a little endian target.
See the info pages for documentation of the MMIX-specific
options.
The following options are available when as is configured
for an Xtensa processor.
--text-section-literals | --no-text-section-literals
With --text-section-literals, literal pools are inter-
spersed in the text section. The default is
--no-text-section-literals, which places literals in a
separate section in the output file. These options only
affect literals referenced via PC-relative "L32R"
instructions; literals for absolute mode "L32R" instruc-
tions are handled separately.
binutils-050707 2011-08-18 15
AS(1) GNU Development Tools AS(1)--absolute-literals | --no-absolute-literals
Indicate to the assembler whether "L32R" instructions
use absolute or PC-relative addressing. The default is
to assume absolute addressing if the Xtensa processor
includes the absolute "L32R" addressing option. Other-
wise, only the PC-relative "L32R" mode can be used.
--target-align | --no-target-align
Enable or disable automatic alignment to reduce branch
penalties at the expense of some code density. The
default is --target-align.
--longcalls | --no-longcalls
Enable or disable transformation of call instructions to
allow calls across a greater range of addresses. The
default is --no-longcalls.
--transform | --no-transform
Enable or disable all assembler transformations of
Xtensa instructions. The default is --transform;
--no-transform should be used only in the rare cases
when the instructions must be exactly as specified in
the assembly source.
SEE ALSOgcc(1), ld(1), and the Info entries for binutils and ld.
COPYRIGHT
Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000,
2001, 2002 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation
License, Version 1.1 or any later version published by the
Free Software Foundation; with no Invariant Sections, with
no Front-Cover Texts, and with no Back-Cover Texts. A copy
of the license is included in the section entitled ``GNU
Free Documentation License''.
binutils-050707 2011-08-18 16
