https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115275
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot
gnu.org
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So looking into the code.
In forwprop2 we have:
iftmp.1_3 = (unsigned int) _13;
b.4_2 = b;
_10 = MAX_EXPR <b.4_2, f_7(D)>;
if (_10 != 0)
goto <bb 5>; [50.00%]
else
goto <bb 6>; [50.00%]
<bb 5> [local count: 536870912]:
<bb 6> [local count: 1073741824]:
# _14 = PHI <f_7(D)(5), 0(4)>
iftmp.3_4 = (unsigned int) _14;
if (iftmp.1_3 != iftmp.3_4)
Why didn't forwprop change `iftmp.1_3 != iftmp.3_4` into `_13 != _14`.
The other thing is:
_10 = MAX_EXPR <b.4_2, f_7(D)>;
if (_10 != 0)
Since this is unsigned, here `max<a,b> != 0` could be `a != 0 | b != 0` which
then will optmize this.
So that is the following:
```
template<class T>
T max(T a, T b)
{
return a > b ? a : b;
}
int f1(unsigned f, unsigned t)
{
return max(f, t) != 0;
}
```
Should be optimized to `(f | t) != 0`.
I will handle this. Min is similar but clang does not optimize that.
