How fast can you count lines?

newlines.c

// another method for
// https://github.com/lemire/Code-used-on-Daniel-Lemire-s-blog/blob/master/2017/02/14/newlines.c

#define haszero(v) (((v) - 0x0101010101010101llu) & ~(v) & 0x8080808080808080llu) // magick provided by https://graphics.stanford.edu/~seander/bithacks.html 

size_t swarcount(char * buffer, size_t size) {
    size_t cnt = 0;
    const uint64_t nls = 0x0a0a0a0a0a0a0a0allu;
    size_t i=0;
    while (i + 8 < size) {
        const uint64_t v = *(uint64_t*)(buffer + i);
        if (haszero(v ^ nls)) {
            for (size_t j=0; j < 8; j++) { 
                if (buffer[i + j] == '\n') cnt ++;
            }
        }

        i += 8;
    }

    for(/**/; i < size; i++)
        if(buffer[i] == '\n') cnt ++;

    return cnt;
}