[Bug fortran/37131] inline matmul for small matrix sizes

[tkoenig at gcc dot gnu dot org]

------- Comment #9 from tkoenig at gcc dot gnu dot org  2010-06-04 22:31 -------
I have thought a little bit about this, and the problem is
a bit daunting ;-)  Of course, this is at least partly because
my experience with the scalarizer is close to non-existant, but you
have to learn sometime.

It seems that the functions for scalarizing do not help a lot
here, because (for example) we need three nested loops for implementing
the case where a and b are of rank 2.

The preferred way would therefore be to state the rank 2 * rank 2 problem as

  do i=1,m
     do j=1,n
        c(i,j) = sum(a(i,:) * b(:,j))
     end do
  end do

with the inner dot product borrowed using the scalarizer (borrowing
from dot_product), and the outer loops using either hand-crafted
TREE code or calling the DO translation.

Comments?  Is this reasonable?


-- 

tkoenig at gcc dot gnu dot org changed:

           What    |Removed                     |Added
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                 CC|                            |pault at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37131