https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126703
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- I wonder if we can have value_range::sign_bit () and thus can fold copysign (x, t) with known signbit of 't' to copysign (x, -1) or copysign (x, 1) and for same sign_bit of x and t elide it?
