[Bug tree-optimization/93080] insert of an extraction on the same location is not optimized

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93080

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's a bugfix so applicable for stage3...  pre-approved with a testcase.

wonder how complicated it would be to handle

vector int g(vector int a)
{
  int b = a[0];
  (*(vector unsigned int *)&a)[0] = b;
  return a;
}

or punned int/float.  Probably doesn't happen in practice though.