title: clang compiler being able to offload OpenMP region to GPU
body: <p>I read that clang compiler can offload OpenMP regions to GPUs. However, I am
  confused on the way to compile the code with clang. The clang version that is 
  installed in our cluster is 3.9.0 (tags/RELEASE_390/final 288133). The code I
  want to offload is basically a matrix-matrix multiplication:</p>
  
  <pre><code>#pragma omp target parallel for  shared(C,P,T) private(i,j,k)
    for (i=0; i&lt;N; i++) {
      for (j=0; j&lt;N; j++) {
        for (k=0; k&lt;N; k++) {
          C[i][j] += P[i][k]*T[k][j];
        }
      }
    }
  </code></pre>
  
  <p>I am compiling with </p>
  
  <pre><code>clang -O3 -fopenmp-targets=x86_64-unknown-linux-gnu mm.c
  clang-3.9: warning: argument unused during compilation: '-fopenmp-targets=x86_64-unknown-linux-gnu'
  </code></pre>
  
  <p>What I don't know is if my installed version of clang is being able to offload code to GPUs and if so, how could I do it. Any comment is welcome.</p>