sub bob { print 'bob'; }

my $match = \&bob;
my $nomatch = sub { print 'nob'; };
*alias = \&bob;

for my $key (keys %main::) {
    if ($match == \&{$key}) {
        print "matched to $key\n";
    }
    if ($nomatch == \&{$key}) {
        print "matched to $key\n";
    }
}