use strict;
use warnings;
use Benchmark 'cmpthese';

my $x;

cmpthese(-1, {
    'eval'   => \&eval_code,
    'noeval' => \&no_eval_code,
 });

sub eval_code {
     $x=1;
     eval {
        some_more_code ();
     };
     if ($@) {
         error_sub();
     }
}

sub no_eval_code {
    if ($x==0) {
        error_sub();
    }
    else {
        $x=0;
        some_more_code ();
    }
}

sub some_more_code { $x++ }
sub error_sub { }