[Bug tree-optimization/90437] Overflow detection too late for VRP

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90437

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to JunMa from comment #2)
> (In reply to Richard Biener from comment #1)
> > VRP obviously only sees a + b in [0, 20] and [0, 20] < [0, 10] as unknown.
> 
> we do have pattern x+y < y in match.pd, but it only worked with
> TYPE_OVERFLOW_UNDEFINED. 
> 
> I'm not sure wether we can use range info in match.pd.

We already do via expr_not_equal_to ().