Function libdivide_s64_do

numpy/core/include/numpy/libdivide/libdivide.h:1125–1152

}

int64_t libdivide_s64_do(int64_t numer, const struct libdivide_s64_t *denom) {
    uint8_t more = denom->more;
    uint8_t shift = more & LIBDIVIDE_64_SHIFT_MASK;

    if (!denom->magic) { // shift path
        uint64_t mask = (1ULL << shift) - 1;
        uint64_t uq = numer + ((numer >> 63) & mask);
        int64_t q = (int64_t)uq;
        q >>= shift;
        // must be arithmetic shift and then sign-extend
        int64_t sign = (int8_t)more >> 7;
        q = (q ^ sign) - sign;
        return q;
    } else {
        uint64_t uq = (uint64_t)libdivide_mullhi_s64(denom->magic, numer);
        if (more & LIBDIVIDE_ADD_MARKER) {
            // must be arithmetic shift and then sign extend
            int64_t sign = (int8_t)more >> 7;
            // q += (more < 0 ? -numer : numer)
            // cast required to avoid UB
            uq += ((uint64_t)numer ^ sign) - sign;
        }
        int64_t q = (int64_t)uq;
        q >>= shift;
        q += (q < 0);
        return q;
    }
}

int64_t libdivide_s64_branchfree_do(int64_t numer, const struct libdivide_s64_branchfree_t *denom) {
    uint8_t more = denom->more;