This chapter describes command-line options available in all versions of the GNU assembler; see section Machine Dependent Features, for options specific to particular machine architectures.
If you are invoking as via the GNU C compiler (version 2), 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
emits a listing to standard output with high-level and assembly source.
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, including the assembler.)
-a[dhlns]These options enable listing output from the assembler. By itself, `-a' requests high-level, assembly, and symbols listing. You can use other letters to select specific options for the list: `-ah' requests a high-level language listing, `-al' requests an output-program assembly listing, and `-as' requests a symbol table listing. High-level listings require that a compiler debugging option like `-g' be used, and that assembly listings (`-al') be requested also.
Use the `-ad' option to omit debugging directives from the listing.
Once you have specified one of these options, you can further control
listing output and its appearance using the directives .list,
.nolist, .psize, .eject, .title, and
.sbttl.
The `-an' option turns off all forms processing.
If you do not request listing output with one of the `-a' options, the
listing-control directives have no effect.
The letters after `-a' may be combined into one option, e.g., `-aln'.
-D
This option has no effect whatsoever, but it is accepted to make it more
likely that scripts written for other assemblers also work with
as.
-f`-f' should only be used when assembling programs written by a (trusted) compiler. `-f' stops the assembler from doing whitespace and comment preprocessing on the input file(s) before assembling them. See section Preprocessing.
Warning: if you use `-f' when the files actually need to be preprocessed (if they contain comments, for example),
asdoes not work correctly.
.include search path: -I path
Use this option to add a path to the list of directories
as searches for files specified in .include
directives (see section .include "file"). You may use -I as
many times as necessary to include a variety of paths. The current
working directory is always searched first; after that, as
searches any `-I' directories in the same order as they were
specified (left to right) on the command line.
-K
as sometimes alters the code emitted for directives of the form
`.word sym1-sym2'; see section .word expressions.
You can use the `-K' option if you want a warning issued when this
is done.
-L
Labels beginning with `L' (upper case only) are called local
labels. See section Symbol Names. Normally you do not see such labels when
debugging, because they are intended for the use of programs (like
compilers) that compose assembler programs, not for your notice.
Normally both as and ld discard such labels, so you do not
normally debug with them.
This option tells as to retain those `L...' symbols
in the object file. Usually if you do this you also tell the linker
ld to preserve symbols whose names begin with `L'.
By default, a local label is any label beginning with `L', but each target is allowed to redefine the local label prefix. On the HPPA local labels begin with `L$'.
-o
There is always one object file output when you run as. By
default it has the name
`a.out' (or `b.out', for Intel 960 targets only).
You use this option (which takes exactly one filename) to give the
object file a different name.
Whatever the object file is called, as overwrites any
existing file of the same name.
-R
-R tells as to write the object file as if all
data-section data lives in the text section. This is only done at
the very last moment: your binary data are the same, but data
section parts are relocated differently. The data section part of
your object file is zero bytes long because all its bytes are
appended to the text section. (See section Sections and Relocation.)
When you specify -R it would be possible to generate shorter
address displacements (because we do not have to cross between text and
data section). We refrain from doing this simply for compatibility with
older versions of as. In future, -R may work this way.
When as is configured for COFF output,
this option is only useful if you use sections named `.text' and
`.data'.
-R is not supported for any of the HPPA targets. Using
-R generates a warning from as.
--statistics
Use `--statistics' to display two statistics about the resources used by
as: the maximum amount of space allocated during the assembly
(in bytes), and the total execution time taken for the assembly (in CPU
seconds).
-vYou can find out what version of as is running by including the option `-v' (which you can also spell as `-version') on the command line.
-W
as should never give a warning or error message when
assembling compiler output. But programs written by people often
cause as to give a warning that a particular assumption was
made. All such warnings are directed to the standard error file.
If you use this option, no warnings are issued. This option only
affects the warning messages: it does not change any particular of how
as assembles your file. Errors, which stop the assembly, are
still reported.
-Z
After an error message, as normally produces no output. If for
some reason you are interested in object file output even after
as gives an error message on your program, use the `-Z'
option. If there are any errors, as continues anyways, and
writes an object file after a final warning message of the form `n
errors, m warnings, generating bad object file.'