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
