Function npy_memchr

numpy/core/src/multiarray/common.h:262–306

* The code below currently makes use of !NPY_ALIGNMENT_REQUIRED, which * should be OK but causes the clang sanitizer to warn. It may make * sense to modify the code to avoid this "unaligned" access but * it would be good to carefully check the performance changes. */

     * it would be good to carefully check the performance changes.
     */
    __attribute__((no_sanitize("alignment")))
#endif
static inline char *
npy_memchr(char * haystack, char needle,
           npy_intp stride, npy_intp size, npy_intp * psubloopsize, int invert)
{
    char * p = haystack;
    npy_intp subloopsize = 0;

    if (!invert) {
        /*
         * this is usually the path to determine elements to process,
         * performance less important here.
         * memchr has large setup cost if 0 byte is close to start.
         */
        while (subloopsize < size && *p != needle) {
            subloopsize++;
            p += stride;
        }
    }
    else {
        /* usually find elements to skip path */
        if (!NPY_ALIGNMENT_REQUIRED && needle == 0 && stride == 1) {
            /* iterate until last multiple of 4 */
            char * block_end = haystack + size - (size % sizeof(unsigned int));
            while (p < block_end) {
                unsigned int  v = *(unsigned int*)p;
                if (v != 0) {
                    break;
                }
                p += sizeof(unsigned int);
            }
            /* handle rest */
            subloopsize = (p - haystack);
        }
        while (subloopsize < size && *p == needle) {
            subloopsize++;
            p += stride;
        }
    }

    *psubloopsize = subloopsize;

    return p;
}


/*