pub const Asm = struct {
    src_node: i32,
    // null-terminated string index
    asm_source: NullTerminatedString,
    /// 1 bit for each outputs_len: whether it uses `-> T` or not.
    ///   0b0 - operand is a pointer to where to store the output.
    ///   0b1 - operand is a type; asm expression has the output as the result.
    /// 0b0X is the first output, 0bX0 is the second, etc.
    output_type_bits: u32,

    pub const Output = struct {
        /// index into string_bytes (null terminated)
        name: NullTerminatedString,
        /// index into string_bytes (null terminated)
        constraint: NullTerminatedString,
        /// How to interpret this is determined by `output_type_bits`.
        operand: Ref,
    };

    pub const Input = struct {
        /// index into string_bytes (null terminated)
        name: NullTerminatedString,
        /// index into string_bytes (null terminated)
        constraint: NullTerminatedString,
        operand: Ref,
    };
}