[Bug tree-optimization/19832] don't remove an if when we know the value is the same as with the if (subtraction)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19832

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 55822
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55822&action=edit
Patch which I am testing