$ perl -del
DB<1> x 0+( () = join('','','x'x(1<<30),'') =~ m{}g )
0 1
DB<2> x 0+( () = join('','','x'x(1<<31),'') =~ m{}g )
0 0
DB<3> x 0+( () = join('','','x'x((1<<31)-8),'') =~ m{}g )
0 1
DB<4> x 0+( () = join('','','x'x((1<<31)-7),'') =~ m{}g )
0 0