AS(1) GNU Development Tools AS(1)
NAME
AS - 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] [@FILE]
[--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=com
mon_v10_v32]
Target D10V options:
[-O]
Target D30V options:
[-O|-n|-N]
Target i386 options:
[--32|--64] [-n]
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 M32C options:
[-m32c|-m16c]
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]
[-mdsp] [-mno-dsp]
[-mmt] [-mno-mt]
[-mdebug] [-no-mdebug]
[-mpdr] [-mno-pdr]
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 |-me ]
Target Z80 options:
[-z80] [-r800]
[ -ignore-undocumented-instructions] [-Wnud]
[ -ignore-unportable-instructions] [-Wnup]
[ -warn-undocumented-instructions] [-Wud]
[ -warn-unportable-instructions] [-Wup]
[ -forbid-undocumented-instructions] [-Fud]
[ -forbid-unportable-instructions] [-Fup]
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 others, including object file formats, most
assembler directives (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, weve tried to make as
assemble correctly everything that other assemblers for the same
machine would assemble. Any exceptions are documented explicitly.
This doesnt mean as always uses the same syntax as another assembler
for the same architecture; for example, we know of several incompatible
versions of 680x0 assembly language syntax.
Each time you run as it assembles exactly one source program. 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 terminal. 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 assembly.
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 argu
ments 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 listing to stan
dard 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 compiler driver with the -v option to
see precisely what options it passes to each compilation pass, includ
ing the assembler.)
OPTIONS
@file
Read command-line options from file. The options read are inserted
in place of the original @file option. If file does not exist, or
cannot be read, then the option will be treated literally, and not
removed.
Options in file are separated by whitespace. A whitespace charac
ter may be included in an option by surrounding the entire option
in either single or double quotes. Any character (including a
backslash) may be included by prefixing the character to be
included with a backslash. The file may itself contain additional
@file options; any such options will be processed recursively.
-a[cdhlmns]
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 Altmacro,,".altmacro".
-D Ignored. This option is accepted for script compatibility 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 leading 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.
--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 exten
sion 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 supported 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 Dont warn about signed overflow.
-K Issue warnings when difference tables altered for long displace
ments.
-L
--keep-locals
Keep (in the symbol table) local symbols. On traditional 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 con
tinuation 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.
-o objfile
Name the object-file output from as objfile.
-R Fold the data section into the text section.
Set the default size of GASs hash tables to a prime number close
to number. Increasing this value can reduce the length of time it
takes the assembler to perform its tasks, at the expense of
increasing the assemblers memory requirements. Similarly reducing
this value can reduce the memory requirements at the expense of
speed.
--reduce-memory-overheads
This option reduces GASs 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
Dont 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.
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 interworking 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.
-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 displace
ments; error if necessary.
The following options are available when as is configured for the Ubi
com IP2K series.
-mip2022ext
Specifies that the extended IP2022 instructions are allowed.
-mip2022
Restores the default behaviour, which restricts the permitted
instructions to just the basic IP2022 ones.
The following options are available when as is configured for the Rene
sas M32C and M16C processors.
-m32c
Assemble M32C instructions.
-m16c
Assemble M16C instructions (the default).
The following options are available when as is configured for the Rene
sas M32R (formerly Mitsubishi M32R) series.
--m32rx
Specify which processor in the M32R family is the target. 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 constructs are
encountered.
--no-warn-explicit-parallel-conflicts or --Wnp
Do not produce warning messages when questionable parallel con
structs 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.
-m68000 | -m68008 | -m68010 | -m68020 | -m68030
| -m68040 | -m68060 | -m68302 | -m68331 | -m68332
| -m68333 | -m68340 | -mcpu32 | -m5200
Specify what processor in the 68000 family is the target. The
default is normally the 68020, but this can be changed at configu
ration time.
-m68881 | -m68882 | -mno-68881 | -mno-68882
The target machine does (or does not) have a floating-point copro
cessor. The default is to assume a coprocessor for 68020, 68030,
and cpu32. Although the basic 68000 is not compatible with the
68881, a combination of the two can be specified, since its possi
ble to do emulation 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
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 extension.
-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 extensions.
The following options are available when as is configured for a pico
Java processor.
-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 con
ditional 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:
-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 Ultra
SPARC 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 architecture.
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 dont
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 refer
enced 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
-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 instruc
tions.
-mdebug
-no-mdebug
Cause stabs-style debugging output to go into an ECOFF-style .mde
bug 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 registers to be treated as 32
bits wide at all times. -mgp32 controls the size of general-pur
pose registers and -mfp32 controls the size of floating-point reg
isters.
-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 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 Extension. This
tells the assembler to accept MDMX instructions. -no-mdmx turns
off this option.
-mdsp
-mno-dsp
Generate code for the DSP Application Specific Extension. This
tells the assembler to accept DSP instructions. -mno-dsp turns off
this option.
-mmt
-mno-mt
Generate code for the MT Application Specific Extension. This
tells the assembler to accept MT instructions. -mno-mt turns off
this option.
--construct-floats
--no-construct-floats
The --no-construct-floats option disables the construction of dou
ble 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 tar
get, 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 endianness. The available configuration names are: mipsec
off, mipself, mipslecoff, mipsbecoff, mipslelf, mipsbelf. The
first two do not alter the default endianness from that of the pri
mary 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 target. 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 configurations, with more
fine-grained control over the assemblers behavior, and will be
supported for more processors.
-nocpp
as ignores this option. It is accepted for compatibility with the
native tools.
--trap
--no-trap
--break
--no-break
Control how to deal with multiplication overflow and division by
zero. --trap or --no-break (which are synonyms) take a trap excep
tion (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 controls 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 interspersed 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" instructions are
handled separately.
--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. Otherwise, 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 instruc
tions. 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.
The following options are available when as is configured for a Z80
family processor.
-z80
Assemble for Z80 processor.
-r800
Assemble for R800 processor.
-ignore-undocumented-instructions
-Wnud
Assemble undocumented Z80 instructions that also work on R800 with
out warning.
-ignore-unportable-instructions
-Wnup
Assemble all undocumented Z80 instructions without warning.
-warn-undocumented-instructions
-Wud
Issue a warning for undocumented Z80 instructions that also work on
R800.
-warn-unportable-instructions
-Wup
Issue a warning for undocumented Z80 instructions that do notwork
on R800.
-forbid-undocumented-instructions
-Fud
Treat all undocumented instructions as errors.
-forbid-unportable-instructions
-Fup
Treat undocumented Z80 intructions that do notwork on R800 as
errors.
SEE ALSO
gcc(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
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binutils-2.17 2006-06-23 AS(1)
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