Overview of as, the GNU AssemblerContents|Index|Next Overview
of as,
the GNU assembler The
following documentation serves as a overview to the user guide for the
GNU assembler, as.
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—that
is, all listings turned on.
-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).
--help
Print a summary of the command
line 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 (in the symbol table)
local symbols, starting with L.
-o
objfile
Name the object-file output
from as objfile.
-R
Fold the data section into
the text section.
--statistics
Print the maximum space
(in bytes) and total time (in seconds) used by assembly.
-v
-version
Print the as
version.
--version
Print the as
version and exit.
-W
Suppress warning messages.
-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 the Intel 80960 processor.
Specify what processor in
the 68000 family is the target. 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 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 it’s possible 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.
The following
options are available when as
is configured for the SPARC architecture.
-Av6 | -Av7 | -Av8 | -Asparclite
| -Av9 | -Av9a
Explicitly select a variant
of the SPARC architecture.
-xarch=v8plus | -xarch=v8plusa
For compatibility with the
Solaris v9 assembler. These options are equivalent to -Av9
and -Av9a,
respectively.
-bump
Warn when the assembler
switches to another architecture.
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
Generate code for a particular
MIPS Instruction Set Architecture level. -mips1
corresponds to the R2000 and R3000 processors, -mips2
to the R6000 processor, and -mips3
to the R4000 processor.
-m4650
-no-m4650
Generate code for the MIPS
R4650 chip. This tells the assembler to accept the mad
and madu
instruction, and to not schedule nop
instructions around accesses to the HI
and LO
registers. -no-m4650
turns off this option.
-mcpu=CPU
Generate code for a particular
MIPS CPU. This has little effect on the assembler, but it is passed by
gcc.
--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 endianness. 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 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 formats.
Eventually, this option will
support more configurations, 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 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 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.
