Function emit_optimized_linear_body 

fn emit_optimized_linear_body<W: Write>(
    w: &mut W,
    func: &Function,
    cfg: &FunctionCfg,
    callee_args: &BTreeMap<u32, u8>,
    used_s: &mut BTreeSet<usize>,
    non_volatile_count: u16,
    volatile_count: u16,
) -> Result<()>