vectorizer data dependency graph

[Sebastian Pop]

On 11/15/06, Sashan Govender <sashang@gmail.com> wrote:
> On 11/15/06, Daniel Berlin <dberlin@dberlin.org> wrote:
> > On 11/14/06, Sashan Govender <sashang@gmail.com> wrote:
> > > Hi
> > >
> > > I was looking at the vectorizer
> > > (http://gcc.gnu.org/projects/tree-ssa/vectorization.html) and noticed
> > > that in section 6 it says that there is no data dependence graph
> > > implemented. Also had a search throught the mailing list archives and
> > > noticed that although ddg.c exists its not used much?
> > > (http://gcc.gnu.org/ml/gcc/2005-09/msg00661.html). A grep for
> > > creat_ddg shows it's used in modulo-sched.c. So is this fertile ground
> > > for something to be implemented? Is it worth implementing a ddg graph
> > > for the vectorizer?
> >
> > What exactly do you hope to gain by building a ddg?
> > If you have some algorithm that can take advantage of a ddg, sure, build one.
> >
>
> No algorithm in particular - I thought someone else might find it
> useful (which is why I asked).
>

There is a ddg in this patch if somebody wants the classic Allen&Kennedy
way to look at the dependences:
http://gcc.gnu.org/wiki/OptimizationCourse?action=AttachFile&do=get&target=loop-distribution-patch-against-gcc-4.1.0-release.patch

Sebastian