[Bug tree-optimization/82697] [6/7/8 Regression] Wrong optimization with aliasing and "if"

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82697

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 42460
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42460&action=edit
untested patch