https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110992
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- So I think this is because ethread can understand `(a & b)!=0` but not `(a*c)!=0` that is a*c != 0 means that a or c will both be non-zero (especially since a*c is known to not to overflow as c as a range of [0,1]).
