How to do prefetching

Questions
#1

I want to achieve prefetching for w in the schedule as follows:

    for(int pf=0; pf<PREFETCH; pf++) {
        w[pf] = weights[weight_addr]; weight_addr += SUB_GROUP_SIZE;
    }

    uint wi = 0;
    uint kr = 0; // kr = Kernel Row
    LOOP(FILTER_SIZE_Y, kr,  // LOOP is a macro that unrolls the loop.
    {
        uint kc = 0; // kc = Kernel Column
        LOOP(FILTER_SIZE_X, kc,
        {
            w[wi % PREFETCH] = weights[weight_addr];
            weight_addr += SUB_GROUP_SIZE; 
            wi++;
        });
    });
    // addr went beyond due to prefetch so move it back to correct location.
    weight_addr -= PREFETCH * SUB_GROUP_SIZE;
}

How shall I achieve that? Should I use double_buffer?

#2

BTW, double buffer doesn’t help me here.