https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102950
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |11.3
Ever confirmed|0 |1
Last reconfirmed| |2021-10-27
Summary|[11 Regression] Dead Code |[11/12 Regression] Dead
|Elimination Regression at |Code Elimination Regression
|-O3 (trunk&11.2.0 vs |at -O3 (trunk&11.2.0 vs
|10.3.0) |10.3.0)
Status|UNCONFIRMED |NEW
Keywords| |missed-optimization
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
In GCC 10, forwprop2 gets:
a.0_1 = a;
_2 = (int) a.0_1;
_3 = _2 ^ 233;
_4 = (unsigned int) _3;
b_7 = (char) _4;
a = b_7;
if (b_7 != 0)
goto <bb 6>; [34.00%]
else
goto <bb 3>; [66.00%]
<bb 3> [local count: 708669601]:
if (_4 <= 1)
goto <bb 4>; [41.00%]
else
goto <bb 6>; [59.00%]
<bb 4> [local count: 290554533]:
if (_4 == 0)
goto <bb 5>; [33.00%]
else
goto <bb 6>; [67.00%]
<bb 5> [local count: 95882995]:
foo ();
While in GCC 11 we get:
a.0_1 = a;
_2 = (int) a.0_1;
_3 = _2 ^ 233;
_4 = (unsigned int) _3;
b_7 = (char) _4;
a = b_7;
if (b_7 != 0)
goto <bb 5>; [34.00%]
else
goto <bb 3>; [66.00%]
<bb 3> [local count: 708669601]:
if (_4 <= 1)
goto <bb 4>; [25.50%]
else
goto <bb 5>; [74.50%]
I still can't figure out why forwprop2 can do it in GCC 10 but not in GCC 11.
