[Bug tree-optimization/94802] Failure to recognize identities with __builtin_clz

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94802

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
Which means it won't help for foo():

  <bb 2> :
  if (b_2(D) >= a_3(D))
    goto <bb 3>; [INV]
  else
    goto <bb 4>; [INV]

  <bb 3> :
  iftmp.0_5 = b_2(D) - a_3(D);

  <bb 4> :
  # iftmp.0_1 = PHI <iftmp.0_5(3), 0(2)>
  return iftmp.0_1;