[Bug tree-optimization/108447] [13 Regression] glibc math/test-*-iseqsig failures

[aldyh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108447

--- Comment #11 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
Hmmm, I wonder if we could do this all in validate_relation like Andrew had
planned.

If NAN is a possibility in either x or y, then we could disallow any relation
recording right off the bat, and avoid any special casing in union/intersect. 
Perhaps allow the != relation even if NAN?