https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104639
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
One thing is not threading through loop latches, but in this case once the loop
is optimized into straight line code in thread2 we don't thread that further,
so end up with
if (i_2(D) == 4)
goto <bb 4>; [97.00%]
else
goto <bb 3>; [3.00%]
<bb 3> [local count: 3540129]:
<bb 4> [local count: 118111600]:
# i_6 = PHI <i_2(D)(3), 6(2)>
_3 = i_6 != 0;
return _3;
For the result, the
i_6 = i_2(D) == 4 ? 6 : i_2(D);
is equivalent to just i_2(D) because we only care whether it is non-zero and
both 4 and 6 are non-zero.
