[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 #9 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #4)
> I see fold_using_range::relation_fold_and_or
> which sees relation1 VREL_LE and relation2 VREL_GE and !is_and, and because
> of
> relation_union (relation1, relation2) == VREL_VARYING fold it to 1.
> But for floating point comparisons, LE | GE is not always true, it is true if
> neither operand is NAN, otherwise false.

Ah, it was the union not the intersect.  So we need something here that would
avoid resolving this to 1 if maybe_isnan() is true for either source operand.