Hi Sandra,
The attached patch implements delinearization of array accesses in the
Fortran front end, something that has been discussed for a long time.
Definitely - among others, this is the subject of PR 14741, which is by
now quite historic.
I've been asked to try to get this patch committed on the OG10 branch
since it is blocking some further optimization work with Graphite for
OpenACC kernels regions. I have a mainline version of this patch as
well that I can send to anyone interested in trying it out, but TBH, I
don't think this is ready for mainline yet.
That would be indeed interesting. Could you post that to the list as
well?
The current status is that
there are still two gfortran tests that are regressing
(gfortran.dg/graphite/id-9.f and
gfortran.dg/vect/fast-math-mgrid-resid.f), and while it's been confirmed
that this helps with Graphite optimizations as intended, we haven't yet
run any benchmarks to confirm that it doesn't make other things slower.
It is probably too late; this could go in for the next stage 1.
(It might, for instance, be appropriate to only delinearize when
Graphite optimizations are also enabled.)
Makes sense.
Does the patch actually make loop interchange for matrix multiplication
work (done with C for loops or Fortran DO loops), or is there additional
work required?
Regarding scalarized loops: We still to not collapse loops for
subroutine foo(a)
real, dimension(:,:), contiguous :: a
a = 5.
end subroutine foo
so an extension to scalarized loops would be quite valuable.
It would be interesting to see if
subroutine foo(a,n,m)
real, dimension(n,m) :: a
do j=1,m
do i=1,n
a(i,j) = 5.
end do
end do
end subroutine foo
is collapsed to a single loop with the patch and Graphite.
Best regards
Thomas
