If you have access to the BMI2 instruction set I can do branchless UTF-8 encoding like in the article using only 9 instructions and 73 bytes of lookup tables:

    branchless_utf8:
        mov     rax, rdi
        lzcnt   ecx, esi
        lea     rdx, [rip + .L__unnamed_1]
        movzx   ecx, byte ptr [rcx + rdx]
        lea     rdx, [rip + example::DEP_AND_OR::h78cbe1dc7fe823a9]
        pdep    esi, esi, dword ptr [rdx + 8*rcx]
        or      esi, dword ptr [rdx + 8*rcx + 4]
        movbe   dword ptr [rdi], esi
        mov     qword ptr [rdi + 8], rcx
        ret

    static DEP_AND_OR: [(u32, u32); 5] = [
        (0, 0),
        (0b01111111_00000000_00000000_00000000, 0b00000000_00000000_00000000_00000000),
        (0b00011111_00111111_00000000_00000000, 0b11000000_10000000_00000000_00000000),
        (0b00001111_00111111_00111111_00000000, 0b11100000_10000000_10000000_00000000),
        (0b00000111_00111111_00111111_00111111, 0b11110000_10000000_10000000_10000000),
    ];

    const LEN: [u8; 33] = [
        // 0-10 leading zeros: not valid.
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        // 11-15 leading zeros: 4 bytes.
        4, 4, 4, 4, 4,
        // 16-20 leading zeros: 3 bytes.
        3, 3, 3, 3, 3,
        // 21-24 leading zeros: 2 bytes.
        2, 2, 2, 2,
        // 25-32 leading zeros: 1 byte.
        1, 1, 1, 1, 1, 1, 1, 1,
    ];

    pub unsafe fn branchless_utf8(codepoint: u32) -> ([u8; 4], usize) {
        let leading_zeros = codepoint.leading_zeros() as usize;
        let bytes = LEN[leading_zeros] as usize;
        let (mask, or) = *DEP_AND_OR.get_unchecked(bytes);
        let ret = core::arch::x86_64::_pdep_u32(codepoint, mask) | or;
        (ret.swap_bytes().to_le_bytes(), bytes)
    }