[Bug tree-optimization/112104] loop of ^1 should just be reduced to ^(n&1)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112104

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-10-27
             Status|UNCONFIRMED                 |NEW

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  I think it should apply even to

int
foo(long n3, int j, int x) {
  for(int i=0; i<n3; i++)
    j=j^x;
  return j;
}

which alternates between 'j' and 'j^x', thus the result
is n3&1 ? j^x : j?

I wonder if there's some online symbolic calculus service that we can
feed IL during compilation ;)