[Bug tree-optimization/64450] Optimize 0>=p-q to q>=p for char*p,*q;

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64450

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(for cmp (tcc_comparison)
 (simplify
  (cmp (pointer_diff @0 @1) integer_zero_p)
  (cmp @0 @1)))

Maybe ....

But we might also need handle the match patterns for too:
A CMP B ? A - B : -(A - B)
A CMP B ? A - B : B - A

(which is also on my todo list anyways).