[Bug tree-optimization/91882] boolean XOR tautology missed optimisation

[Bug tree-optimization/91882] boolean XOR tautology missed optimisation

[sucicf1 at outlook dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91882

Ivan Sučić <sucicf1 at outlook dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sucicf1 at outlook dot com

--- Comment #4 from Ivan Sučić <sucicf1 at outlook dot com> ---
I have added im match.pd a simplify. But fir unknown reason IT doesn't het
applied.  Anybody knows why?

[Bug tree-optimization/91882] boolean XOR tautology missed optimisation

[sucicf1 at outlook dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91882

--- Comment #5 from Ivan Sučić <sucicf1 at outlook dot com> ---
I have added in match.pd a simplify. But for unknown reason it doesn't get
applied.  Anybody knows why?

[Bug tree-optimization/91882] boolean XOR tautology missed optimisation

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91882

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Depends on|                            |103356

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
After my patch for PR 103356, this is fixed.

Before pre:
  _1 = a_4(D) ^ b_5(D);
  _2 = a_4(D) | b_5(D);
  if (_2 != 0)
    goto <bb 3>; [50.00%]
  else
    goto <bb 4>; [50.00%]

  <bb 3> [local count: 536870913]:
  _6 = a_4(D) & b_5(D);
  _9 = ~_6;

  <bb 4> [local count: 1073741824]:
  # iftmp.0_3 = PHI <_9(3), 0(2)>
  _7 = _1 == iftmp.0_3;


After PRE (after my patch):
  _1 = a_4(D) ^ b_5(D);
  _2 = a_4(D) | b_5(D);
  if (_2 != 0)
    goto <bb 4>; [50.00%]
  else
    goto <bb 3>; [50.00%]

  <bb 3> [local count: 536870912]:
  _10 = ~_1;
  goto <bb 5>; [100.00%]

  <bb 4> [local count: 536870913]:
//  _6 = a_4(D) & b_5(D);
 // _9 = ~_6;

  <bb 5> [local count: 1073741824]:
  # iftmp.0_3 = PHI <_9(4), 0(3)>
  # prephitmp_11 = PHI <_2(4), _10(3)>
  return prephitmp_11;

And then dom comes and does (because if (a|b) == 0 then both a and b are zero
and a^b == 0 and ~(a^b) is 1):
  <bb 2> [local count: 1073741824]:
  _2 = a_4(D) | b_5(D);
  if (_2 != 0)
    goto <bb 4>; [50.00%]
  else
    goto <bb 3>; [50.00%]

  <bb 3> [local count: 536870912]:
  _1 = 0;
  _10 = 1;

  <bb 4> [local count: 1073741824]:
  # prephitmp_11 = PHI <1(2), 1(3)>
  return 1;


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103356
[Bug 103356] bool0 == ~bool1 should simplify to bool1 ^ bool0

[Bug tree-optimization/91882] boolean XOR tautology missed optimisation

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91882

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note comment #1 is not done after the patch for PR103356 .

[Bug tree-optimization/91882] boolean XOR tautology missed optimisation

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91882
Bug 91882 depends on bug 103356, which changed state.

Bug 103356 Summary: bool0 == ~bool1 should simplify to bool1 ^ bool0
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103356

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

[Bug tree-optimization/91882] boolean XOR tautology missed optimisation

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91882

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
comment #0 is now fixed.
Filed PR 107880  for comment #1 since it is a different issue.

[Bug tree-optimization/91882] boolean XOR tautology missed optimisation

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91882

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |13.0