Asm

    pub const Asm = struct {
        src_node: Ast.Node.Offset,
        // 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,
        clobbers: Ref,

        pub const Small = packed struct(u16) {
            is_volatile: bool,
            outputs_len: u7,
            inputs_len: u8,
        };

        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,
        };
    }