[Bug tree-optimization/91540] missed value-replacement in phiopt

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91540

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2019-08-26
            Version|tree-ssa                    |10.0
            Summary|Missed optimization:        |missed value-replacement in
                   |simplification CFG          |phiopt
     Ever confirmed|0                           |1
           Severity|normal                      |enhancement

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm.  So we have

  <bb 2> [local count: 1073741824]:
  _5 = cond1_2(D) & cond2_3(D);
  if (_5 != 0)
    goto <bb 3>; [17.00%]
  else
    goto <bb 4>; [83.00%]

  <bb 3> [local count: 182536110]:

  <bb 4> [local count: 1073741824]:
  # _1 = PHI <42(3), 43(2)>
  return _1;

and value-replacement would be

  _5 = cond1_2(D) & cond2_3(D);
  _6 = (int)_5;
  _7 = _6 ^ 43;
  return _7;

so something for phiopt.  And for the inverse case _6 | 42.

Then only RTL has to elide the bool -> int promotion.