[Bug tree-optimization/110919] [14 Regression] Dead Code Elimination Regression at -O3 since r14-1691-gbc5a2c2e793

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110919

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The first change we get is threadfull1 where there is an extra jump threading.
And then phiopt2 changes:
  <bb 3> [local count: 719407024]:
  if (l_15(D) != 0)
    goto <bb 6>; [50.00%]
  else
    goto <bb 7>; [50.00%]
into:
  <bb 3> [local count: 719407024]:
  _17 = l_15(D) == 0;
  _36 = (int) _17;

And then DOM2 does not do jump threading along:
  <bb 6> [local count: 628138968]:
  # iftmp.1_8 = PHI <_36(3), 0(5)>


As I mentioned in comment #2 we don't see that:
  _19 = _6 == iftmp.1_8;
  _3 = iftmp.1_8 ^ 1;
  _21 = (_Bool) _3;
  _22 = _19 & _21;
  _23 = _6 != 0;
  _5 = _22 & _23;

is always 0.