openpower/sv/cookbook/fortran_maxloc.mdwn

   1 # Fortran MAXLOC SVP64 demo
   2
   3 MAXLOC is a notoriously difficult function for SIMD to cope with.
   4 SVP64 however has similar capabilities to Z80 CPIR and LDIR
   5
   6 <https://bugs.libre-soc.org/show_bug.cgi?id=676>
   7
   8 ```
   9 int m2(int * const restrict a, int n)
  10 {
  11    int m, nm;
  12    int i;
  13
  14    m = INT_MIN;
  15    nm = -1;
  16    for (i=0; i<n; i++)
  17    {
  18        if (a[i] > m)
  19        {
  20            m = a[i];
  21            nm = i;
  22        }
  23     }
  24     return nm;
  25 }
  26 ```
  27
  28 [[!tag svp64_cookbook ]]
  29
  30 Read:
  31 <https://www.intel.com/content/www/us/en/developer/articles/technical/optimizing-maxloc-operation-using-avx-512-vector-instructions.html#gs.12t5y0>
  32
  33 <img src="https://www.intel.com/content/dam/developer/articles/technical/optimizing-maxloc-operation-using-avx-512-vector-instructions/optimizing-maxloc-operation-using-avx-512-vector-instructions-code2.png
  34 " alt="NLnet foundation logo" width="50%" />