Auto-Vectorize comparison

Question

I\'ve problems getting my g++ 5.4 use vectorization for comparison. Basically I want to compare 4 unsigned ints using vectorization. My first approach was straight forward:<

Answer 1

Okay, apparently the compiler does not like "unrolled loops". This works for me:

bool compare(signed int const pX[8]) {
    signed int const w[] __attribute__((aligned(32))) = {1,2,3,4,5,6,7,8};
    signed int out[8] __attribute__((aligned(32)));

    for (unsigned int i = 0; i < 8; ++i) {
        out[i] = (pX[i] <= w[i]);
    }

    bool temp = true;
    for (unsigned int i = 0; i < 8; ++i) {
        temp = temp && out[i];
        if (!temp) {
            return false;
        }
    }
    return true;
}

Please note, that out is also a signed int. Now I'll just need a fast way to combine the result saved in out