Parallel (OpenMP) matmul library function

[FX Coudert]

Hi there,

In its current state, the matmul implementation in libgfortran is  
based on a triple loop, like this:

>       for (y = 0; y < ycount; y++)
>         {
>           bbase_y = bbase + y*bystride;
>           dest_y = dest + y*rystride;
>           for (n = 0; n < count; n++)
>             {
>               abase_n = abase + n*aystride;
>               bbase_yn = bbase_y[n];
>               for (x = 0; x < xcount; x++)
>                 {
>                   dest_y[x] += abase_n[x] * bbase_yn;
>                 }
>             }
>         }

(there are actually several cases depending on the strides involved,  
but you get the idea). I'm thinking we could provide an OpenMP  
version with very little work and added maintainance. I've never used  
OpenMP with C code, so I'm not sure exactly how pointers are handled,  
but I supposed there is a way to parallelize the outer loop. Do you  
think it's possible? Would it be a good thing? (We could introduce a  
new option to call these functions.)

FX

-- 
François-Xavier Coudert
http://www.homepages.ucl.ac.uk/~uccafco/