[PATCH] D14240: Allow LLE/LD and the loop versioning infrastructure to use SCEV predicates

[Adam Nemet via llvm-commits]

anemet added a comment.

Hi Silviu,

In http://reviews.llvm.org/D14240#288784, @sbaranga wrote:

> Hi Adam,
>
> In http://reviews.llvm.org/D14240#283209, @anemet wrote:
>
> > I am not saying we should implement this but I'd like to think about this now before committing to a design where we'd have no way of dropping unnecessary predicates.
> >
> > I am not sure that we need per-dependence predicates though.  I think it needs to be per alias set.  If you have a pointer that may wrap that can now have a dependence to any of the pointers in the same alias set.  It is still OK to drop this predicate for loop distribution if all members of this alias set fall into the same partition.
> >
> > Where are we going to use SCEVPreds with alias checks?  Is it to try to shape a SCEV into an AddRec?
>
>
> Did you get a chance to think about this? Should we start a thread on llvm-dev?
>
> I guess this would block the addition of new SCEV predicate types..


Sorry about the delay.  No, I don't think this should hold up further work.

If we want to tag predicates with either the affected dependences or use some other mechanism is an additional improvement to try to reduce the number of predicates.  As long as we keep the threshold for the number predicates low for distribution we should be good.


http://reviews.llvm.org/D14240