[Bug tree-optimization/121279] [14/15/16 Regression] wrong code due to load of a bool from an union being pulled out of loop

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121279

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #8)
> Created attachment 62127 [details]
> untested patch
> 
> Needs the testcase added, a full bootstrap and some extra comments.
> BUT it looks like it is doing the correct thing.

That is we transform:
  _2 = s_item_mem.D.2962.boolean;


Into:
  _n = MEM<unsigned char>((union *)&s_item_mem + 8B);
  _2 = (_Bool)_n;

When we pull out the load.