[Bug rtl-optimization/84527] missed optimization for special ternary operation

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84527

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
No, signed comparison is very different from unsigned comparison, and only
unsigned comparison < is usable for this.  Borrow flag reflects unsigned signed
comparison result rather than signed.