[Bug tree-optimization/121921] `e - (e - b)` for pointers is not optimized to just b

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121921

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 62505
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=62505&action=edit
New patch under testing