Mac OS X / Darwin man pages : as (1)
as (1)
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as - Mac OS X Mach-O GNU-based assemblers
as [ option ... ] [ file ... ]
The as command translates assembly code in the named files to object
code. If no files are specified, as reads from stdin. All undefined
symbols in the assembly are treated as global. The output of the
assembly is left in the file a.out by default.
The program /usr/bin/as is actually a driver that executes assemblers
for specific target architectures. If no target architecture is specified,
it defaults to the architecture of the host it is running on.
-o name
Name the output file name instead of a.out.
- -arch arch_type
-
Specifies the target architecture, arch_type, of the assembler
to be executed. The target assemblers for each architecture are
in /usr/libexec/gcc/darwin/arch_type/as or
/usr/local/libexec/gcc/darwin/arch_type/as. There is only one
assembler for an architecture family. If the specified target
architecture is a machine-specific implementation, the assembler
for that architecture family is executed (e.g.,
/usr/libexec/gcc/darwin/ppc/as for -arch ppc604e). See arch(3)
for the currently known arch_types.
- -arch_multiple
-
Precede any displayed messages with a line stating the program
name (as) and the architecture (from the -arch arch_type flag),
to distinguish which architecture the error messages refer to.
When the cc(1)
driver program is run with multiple -arch flags,
it invokes as with the -arch_multiple option.
- -force_cpusubtype_ALL
-
By default, the assembler will produce the CPU subtype ALL for
the object file it is assembling if it finds no implementationspecific
instructions. Also by default, the assembler will
allow implementation-specific instructions and will combine the
CPU subtype for those specific implementations. The combining
of specific implementations is architecture-dependent; if some
combination of instructions is not allowed, an error is generated.
With the optional -force_cpusubtype_ALL flag, all
instructions are allowed and the object file's CPU subtype will
be the ALL subtype. If the target architecture specified is a
machine-specific implementation (e.g., -arch ppc603, -arch
i486), the assembler will flag as errors instructions that are
not supported on that architecture, and it will produce an
object file with the CPU subtype for that specific implementation
(even if no implementation-specific instructions are used).
- -dynamic
-
Enables dynamic linking features. This is the default.
- -static
-
Causes the assembler to treat as an error any features for
dynamic linking. Also causes the .text directive to not include
the pure_instructions section attribute.
- --
- Use stdin for the assembly source input.
- -n
- Instructs the assembler not to assume that the assembly file
starts with a .text directive. Use this option when an output
file is not to contain a (__TEXT,__text) section or this section
is not to be first one in the output file.
- -f
- Fast; no need for the assembler preprocessor (``app''). The
assembler preprocessor can also be turned off by starting the
assembly file with #NO_APP\n". This is intended for use by
compilers which produce assembly code in a strict clean format
that specifies exactly where whitespace can go. The assembler
preprocessor needs to be run on hand-written assembly files
and/or files that have been preprocessed by the C preprocessor
cpp. This is typically needed when assembler files are assembled
through the use of the cc(1)
command, which automatically
runs the C preprocessor on assembly source files. The assembler
preprocessor strips out excess spaces, turns single-quoted characters
into a decimal constants, and turns # <number> <filename>
<level> into .line <number>;.file <filename> pairs. When the
assembler preprocessor has been turned off by a #NO_APP\n at
the start of a file, it can be turned back on and off again with
pairs of #APP\n and #NO_APP\n at the beginnings of lines.
This is used by the compiler to wrap assembly statements produced
from asm() statements.
- -g
- Produce debugging information for the symbolic debugger gdb(1)
so that the assembly source can be debugged symbolically. The
debugger depends on correct use of the C preprocessor's #include
directive or the assembler's .include directive: Any include
file that produces instructions in the (__TEXT,__text) section
must be included while a .text directive is in effect. In other
words, there must be a .text directive before the include, and
the .text directive must still be in effect at the end of the
include file. Otherwise, the debugger will get confused when in
that assembly file.
- -v
- Display the version of the assembler (both the Mac OS X version
and the GNU version it is based on).
- -V
- Print the path and the command line of the assembler the assembler
driver is using.
- -Idir
- Add the directory dir to the list of directories to search for
files included with the .include directive. The default place
to search is the current directory.
- -W
- Suppress warnings.
- -L
- Save non-global defined labels beginning with an `L'; these
labels are normally discarded to save space in the resultant
symbol table. The compiler generates such temporary labels.
-static_branch_prediction_Y_bit
Treat a single trailing `+' or `-' after a conditional PowerPC
branch instruction as a static branch prediction that sets the
Y-bit in the opcode. Pairs of trailing ++ or -- always set
the AT-bits. This is the default for Mac OS X.
- -static_branch_prediction_AT_bits
-
Treat a single trailing `+' or `-' after a conditional PowerPC
branch instruction as a static branch prediction that sets the
AT-bits in the opcode. Pairs of trailing ++ or -- always set
the AT-bits but with this option a warning is issued if this
syntax is used. With this flag the assembler behaves like the
IBM tools.
- -no_ppc601
-
Treat any PowerPC 601 instructions as an error.
-mc68000 and -mc68010
Generate branches that the mc68000 and mc68010 can use (that
don't use 32-bit pc-relative jumps and branches, since they are
not implemented on these two processors). Not applicable on
NeXT machines.
- -mc68020
-
Generate branches that use 32-bit pc-relative displacements.
This is the default.
- a.out
- output file
The assembler manual on line in /Developer/Documentation/DeveloperTools/Assembler
The assembler source in the cctools module of the Darwin sources.
cc(1)
, ld(1)
, nm(1)
, otool(1)
, arch(3)
, Mach-O(5)
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