gistfile1.txt

let mut tmp = os::tmpdir();
    tmp.push(Path::new("llvm_tmp"));
    File::create(&tmp).write_str(gen.as_slice()).unwrap();

    match Command::new(format!("llvm-as < {} | opt | llvm-dis", tmp.display())).output() {
        Ok(out) => out.output.to_string(),
        Err(e) => fail!("Fail? {}", e)
    }