graphite loop optimizer - "C" examples?

[Richard Guenther]

On Sun, Jul 29, 2012 at 7:33 PM, Gary Funck <gary@intrepid.com> wrote:
>
> I have been experimenting with the graphite optimizer, based on GCC trunk, and
> cloog-isl.  I started with the attached simple "C" program, which has this
> basic structure.
>
> #define N 20000
> int a[N][N], b[N], c[N];
> [...]
>   for (i = 0; i < N; i++)
>     {
>       b[i] = i;
>       c[i] = i + N;
>     }
>   for (i = 0; i < N; i++)
>     for (j = 0; j < N; j++)
>       a[j][i] = b[i] + c[j];
>
> (Attached, is the full test case.)
>
> And compiled it with: -O3  -floop-block.
>
> Couple of questions:
> 1) What option should I supply to confirm that the graphite optimizer ran and
> determine (i) did it in fact perform any optimizations, and (ii) which
> optimizations did it perform?

You have to look at dump files.

> 2) If -floop-block couldn't optimize this program, what is the likely reason?
> 3) Would you please offer pointers to example "C" programs that highlight
> graphite-cloog-isl optimizations?

Look at the gcc.dg/graphite/ testsuite.

> Thanks,
> - Gary