Ref

    pub const Ref = enum(u32) {
        u0_type,
        u1_type,
        u8_type,
        i8_type,
        u16_type,
        i16_type,
        u29_type,
        u32_type,
        i32_type,
        u64_type,
        i64_type,
        u80_type,
        u128_type,
        i128_type,
        u256_type,
        usize_type,
        isize_type,
        c_char_type,
        c_short_type,
        c_ushort_type,
        c_int_type,
        c_uint_type,
        c_long_type,
        c_ulong_type,
        c_longlong_type,
        c_ulonglong_type,
        c_longdouble_type,
        f16_type,
        f32_type,
        f64_type,
        f80_type,
        f128_type,
        anyopaque_type,
        bool_type,
        void_type,
        type_type,
        anyerror_type,
        comptime_int_type,
        comptime_float_type,
        noreturn_type,
        anyframe_type,
        null_type,
        undefined_type,
        enum_literal_type,
        ptr_usize_type,
        ptr_const_comptime_int_type,
        manyptr_u8_type,
        manyptr_const_u8_type,
        manyptr_const_u8_sentinel_0_type,
        slice_const_u8_type,
        slice_const_u8_sentinel_0_type,
        manyptr_const_slice_const_u8_type,
        slice_const_slice_const_u8_type,
        optional_type_type,
        manyptr_const_type_type,
        slice_const_type_type,
        vector_8_i8_type,
        vector_16_i8_type,
        vector_32_i8_type,
        vector_64_i8_type,
        vector_1_u8_type,
        vector_2_u8_type,
        vector_4_u8_type,
        vector_8_u8_type,
        vector_16_u8_type,
        vector_32_u8_type,
        vector_64_u8_type,
        vector_2_i16_type,
        vector_4_i16_type,
        vector_8_i16_type,
        vector_16_i16_type,
        vector_32_i16_type,
        vector_4_u16_type,
        vector_8_u16_type,
        vector_16_u16_type,
        vector_32_u16_type,
        vector_2_i32_type,
        vector_4_i32_type,
        vector_8_i32_type,
        vector_16_i32_type,
        vector_4_u32_type,
        vector_8_u32_type,
        vector_16_u32_type,
        vector_2_i64_type,
        vector_4_i64_type,
        vector_8_i64_type,
        vector_2_u64_type,
        vector_4_u64_type,
        vector_8_u64_type,
        vector_1_u128_type,
        vector_2_u128_type,
        vector_1_u256_type,
        vector_4_f16_type,
        vector_8_f16_type,
        vector_16_f16_type,
        vector_32_f16_type,
        vector_2_f32_type,
        vector_4_f32_type,
        vector_8_f32_type,
        vector_16_f32_type,
        vector_2_f64_type,
        vector_4_f64_type,
        vector_8_f64_type,
        optional_noreturn_type,
        anyerror_void_error_union_type,
        adhoc_inferred_error_set_type,
        generic_poison_type,
        empty_tuple_type,
        undef,
        undef_bool,
        undef_usize,
        undef_u1,
        zero,
        zero_usize,
        zero_u1,
        zero_u8,
        one,
        one_usize,
        one_u1,
        one_u8,
        four_u8,
        negative_one,
        void_value,
        unreachable_value,
        null_value,
        bool_true,
        bool_false,
        empty_tuple,

        /// This Ref does not correspond to any ZIR instruction or constant
        /// value and may instead be used as a sentinel to indicate null.
        none = std.math.maxInt(u32),

        _,

        pub const static_len = @typeInfo(@This()).@"enum".field_names.len - 1;

        pub fn toIndex(inst: Ref) ?Index {
            assert(inst != .none);
            const ref_int = @backingInt(inst);
            if (ref_int >= static_len) {
                return @fromBackingInt(@intCast(ref_int - static_len));
            } else {
                return null;
            }
        }

        pub fn toIndexAllowNone(inst: Ref) ?Index {
            if (inst == .none) return null;
            return toIndex(inst);
        }
    }