I think that this is what you want.

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";
    }
}
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This will match `bob' and nothing else.

This will only find subroutines in the main package.

Update: Added Alias for completness.