This chapter describes command-line options available in all versions of the gnu assembler; see Machine Dependencies, for options specific to particular machine architectures.
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 listing 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 compiler driver with the -v option to see precisely what options it passes to each compilation pass, including the assembler.)