[Bug libfortran/51119] MATMUL slow for large matrices

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51119

--- Comment #35 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to Jerry DeLisle from comment #34)

> -Ofast does reorder execution.. 

So does a block algorithm.

> Opinions welcome.

I'd say go for -Ofast, or at least its subset that enables
reordering of expressions and thus vectorization.

It might be interesting to check the GOTO BLAS for accuracy, as well.

We could also ask on c.l.f. on what people#s expectations are, but I
shudder to think about the lectures on PL/I that would ensue :-)