[Bug tree-optimization/123983] [16 Regression] wrong code at -O1 -ftree-vectorize on x86_64-pc-linux-gnu

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123983

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Tamar Christina from comment #9)
> IMHO, the right fix is to have it not update out of loop uses that come from
> a live value. The code was intended to fixup the IVs that were not live.
> 
> But will defer to you :)

I'll note the function takes an update_e edge, the edge to update IVs on.  It
also only iterates over that edge destination PHIs.  As said, I'm going to see
where it fails (eventually).