You might consider B. Perhaps something like:

#!/usr/local/bin/perl
use strict;
use warnings;
use B;

HERE:
B::walkoptree(B::main_root(), "print_label");
THERE:
exit(0);


sub B::OP::print_label {
    my $op = shift;
    if(ref($op) eq 'B::COP') {
        my $label = $op->label;
        if(defined($label)) {
            my $file = $op->file;
            my $line = $op->line;
            print "$label: $file: $line\n";
        }
    }
}
[download]

Which produces

HERE: ./test.pl: 6
THERE: ./test.pl: 8
[download]

update: The label, line and file information is stored in the Code tree (a.k.a. OP tree) - not in any stash or pad.