llvm-as [options] [filename]
llvm-as is the LLVM assembler. It reads a file containing human-readable LLVM assembly language, translates it to LLVM bitcode, and writes the result into a file or to standard output.
If filename is omitted or is -, then llvm-as reads its input from standard input.
If an output file is not specified with the -o option, then llvm-as sends its output to a file or standard output by following these rules:
If llvm-as succeeds, it will exit with 0. Otherwise, if an error occurs, it will exit with a non-zero value.