Automake includes some support for assembly code.
The variable AS holds the name of the compiler used to build assembly code. This compiler must work a bit like a C compiler; in particular it must accept -c and -o. The value of ASFLAGS is passed to the compilation. You are required to set AS and ASFLAGS via configure.in. The autoconf macro AM_PROG_AS will do this for you. Unless they are already set, it simply sets AS to the C compiler and ASFLAGS to the C compiler flags.