[Bug tree-optimization/93504] Missed reassociation with constants and not of that constant with IORs

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93504

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I should note this does not block bit-field lowering because store merging did
not optimize it this way either.