[Bug tree-optimization/63169] ivopts rewrite_uses pessimizes debug info

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63169

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
IVOPTs depends on CSE to remove the effect of building its (sometimes gigantic)
GENERIC expressions figuring out IVs and inserting them multiple times.

Not sure if we even try to optimize the IV chosen to replace debuginfo uses.