Re: [patch,libgfortran] PR51119 - MATMUL slow for large matrices

[Jerry DeLisle <jvdelisle at charter dot net>]

On 11/15/2016 07:59 AM, Jerry DeLisle wrote:
> On 11/14/2016 11:22 PM, Thomas Koenig wrote:
> > Hi Jerry,
> >
> > > With these changes, OK for trunk?
> >
> > Just going over this with a fine comb...
> >
> > One thing just struck me:   The loop variables should be index_type, so
> >
> >       const index_type m = xcount, n = ycount, k = count;
> >
> > [...]
> >
> >    index_type a_dim1, a_offset, b_dim1, b_offset, c_dim1, c_offset, i1, i2,
> >           i3, i4, i5, i6;
> >
> >       /* Local variables */
> >       GFC_REAL_4 t1[65536], /* was [256][256] */
> >          f11, f12, f21, f22, f31, f32, f41, f42,
> >          f13, f14, f23, f24, f33, f34, f43, f44;
> >       index_type i, j, l, ii, jj, ll;
> >       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
> >
> > I agree that we should do the tuning of the inline limit
> > separately.
>
> Several of my iterations used index_type. I found using integer gives better
> performance. The reason is that they are of type ptr_diff_t which is a 64 bit
> integer. I suspect we eliminate one memory fetch for each of these and reduce
> the register loading by reducing the number of registers needed, two for one
> situation. I will change back and retest.
>
> and Paul commeneted "-ftree-vectorize turns on -ftree-loop-vectorize and
> -ftree-slp-vectorize already."
>
> I will remove those to options and keep -ftree-vectorize
>
> I will report back my findings.

Changed back to index_type, all OK, must have been some OS stuff running in the 
background.

All comments incorporated. Standing by for approval.

Jerry