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luca_l_
Beginner
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How can I solve this Read-After-Write dependency?

I'm trying to vectorize the inner `for` of this function:

    void SIFTDescriptor::samplePatch(float *vec)
    {
       for (int r = 0; r < par.patchSize; ++r)
       {
          const int br0 = par.spatialBins * bin0; const float wr0 = w0;
          const int br1 = par.spatialBins * bin1; const float wr1 = w1;
          for (int c = 0; c < par.patchSize; ++c)
          {
             const float val = mask.at<float>(r,c) * grad.at<float>(r,c);
    
             const int bc0 = bin0;
             const float wc0 = w0*val;
             const int bc1 = bin1;
             const float wc1 = w1*val;
    
             // ori from atan2 is in range <-pi,pi> so add 2*pi to be surely above zero
             const float o = float(par.orientationBins)*(ori.at<float>(r,c) + 2*M_PI)/(2*M_PI);
    
             int   bo0 = (int)o;
             const float wo1 =  o - bo0;
             bo0 %= par.orientationBins;
    
             int   bo1 = (bo0+1) % par.orientationBins;
             const float wo0 = 1.0f - wo1;
    
             // add to corresponding 8 vec...
             if (wr0*wc0>0) {
                 vec[br0+bc0+bo0] += wr0*wc0 * wo0;
                 vec[br0+bc0+bo1] += wr0*wc0 * wo1;
             }
             if (wr0*wc1>0) {
                 vec[br0+bc1+bo0] += wr0*wc1 * wo0;
                 vec[br0+bc1+bo1] += wr0*wc1 * wo1;
             }
             if (wr1*wc0>0) {
                 vec[br1+bc0+bo0] += wr1*wc0 * wo0;
                 vec[br1+bc0+bo1] += wr1*wc0 * wo1;
             }
             if (wr1*wc0>0) {
                 vec[br1+bc1+bo0] += wr1*wc0 * wo0;
                 vec[br1+bc1+bo1] += wr1*wc0 * wo1;
             }
          }
       }
    }

However, Intel Advisor tells me that there are two Read-After-Write dependencies in:

     vec[br0+bc0+bo0] += wr0*wc0 * wo0;

And:

     vec[br1+bc0+bo0] += wr1*wc0 * wo0;

How can I solve them? This is the first time that I try to solve such a dependency and I'm struggling a little bit...

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