[PATCH] D26277: [SLP] Fixed cost model for horizontal reduction.

[Michael Kuperstein via llvm-commits]

mkuper added a comment.

In https://reviews.llvm.org/D26277#599995, @ABataev wrote:

> In https://reviews.llvm.org/D26277#598814, @mkuper wrote:
>
> > So, now, none of the costs on the tests actually change?
> >  Does that mean that the changes in costs in the previous versions came from the +1?
> >
> > Can you add a test that demonstrates the cost change? (Preferably in a way that shows what happened - e.g. commit a test with the "bad" cost, and then have a diff with the good one).
>
>
> Changed a code a little bit. Checked it, the calculated cost is very close to the real situation, but seems to me the BoUpSLP tree cost is too optimistic. Will look at it later.


I'm sorry, but I'm still confused.
The original rationale for this patch was that the vector cost model is too optimistic, but the only test change seems to show the cost model becoming  even more optimistic.


https://reviews.llvm.org/D26277