[Bug rtl-optimization/109476] Missing optimization for 8bit/8bit multiplication / regression

[klaus.doldinger64 at googlemail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109476

--- Comment #6 from Wilhelm M <klaus.doldinger64 at googlemail dot com> ---
The following "solution"

constexpr uint16_t mul(const uint8_t a, const uint16_t b) {
    const auto aa = std::bit_cast<std::array<uint8_t, 2>>(b);
    return aa[1] * a;
}

or 

constexpr uint16_t mul(const uint8_t a, const uint16_t b) {
    uint8_t aa[2];
    std::memcpy(aa, &b, 2);
    return aa[1] * a;
}

gives optimal result ;-)