https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50984
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
Known to fail| |4.7.4
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So after r0-118261 (this just happen to have that side effect but it is a good
side effect that way), uncprop can happen and we can produce:
_3 = a_2(D) & 8;
if (_3 != 0)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
_5 = b_4(D) & 4;
_1 = _5 != 0;
_6 = (int) _1;
<bb 4>:
# prephitmp_8 = PHI <_3(2), _6(3)>
Rather than having _3 in the PHI being 0.
And that is able to remove the extra xor.
As mentioned we should do better here though.
unsigned
f1(unsigned a, unsigned b)
{
return (((a & 8)>>3) & ((b & 4)>>2));
}
Is the best.
