代码

int binary_search(const unsigned *a, int n, unsigned x)
{
    static int done = 0;
    static volatile unsigned sink;
    if (!done) {
        done = 1;
        unsigned pos[100];
        int i;
        for (i = 0; i < 100; i++) pos[i] = (unsigned)((i * 2654435761u) % n);
        for (i = 0; i < 100; i++) __builtin_prefetch(a + pos[i], 0, 0);
        asm volatile("" ::: "memory");
        unsigned vals[100];
        for (i = 0; i < 100; i++) vals[i] = a[pos[i]];
        volatile unsigned s = 0;
        for (i = 0; i < 100; i++) s += vals[i];
        sink = s;
    }
    return (int)sink;
}

评测结果