Re: [PATCH] tree-optimization/113552 - fix num_call accounting in simd clone vectorization

[Jakub Jelinek <jakub@redhat.com>]

On Tue, Jan 23, 2024 at 01:40:15PM +0100, Richard Biener wrote:
> It's never going to be 3 vs 2 but 3 * 2^n vs. 3 * 2^m so floor or
> ceil doesn't matter.  In fact we could have just using
> some inverse of exact_log2 (n->simdclone->simdlen).  That is,
> it's only simdlen that's varying in this addend to this_badness.
> 
> For the exact_log2 case the behavior is unchanged and we now only
> get a sensible number for the others now.  Maybe log2 was for the
> fear of overflow or over-accounting compared to the other increments.
> When overflow is not an issue we could also use
> floor_log2 (num_calls * 4096) to be more "precise".  I don't know
> why we have all these different weights and why they are the way
> they are - but it's a lot of apples and oranges we put together
> in a magic number to compare ;)
> 
> I prefer to do a minimal change now, but both floor and ceil work
> for me, so if you prefer I can change (but as said, it would only
> matter with the mixing with the other cost factors, and in unknown
> ways since the desire is not spelled out).

Ok as is then.

	Jakub