That is certainly not irreversible. The output from Stunnix Perl-Obfus is more perl code. Running the output from that program through B::Deparse and/or PerlTidy cleans it up nicely. All the symbols are still named oddly but that shouldn't be a challenge to any would-be source code reader.

So yes, it makes the source painful to work with. Its a fallacy to assert that it is irreversable.

require(File::Temp);
my($z5da4d3837d, $zc11e41b4ef) = File::Temp::tempfile('UNLINK', 1);
my $z9e5935eea4;
if (@z6a703c020a) {
    my($z5a5fa8125d, $zcc158ad3e0) = File::Temp::tempfile('UNLINK', 1)
+;
    print $z5a5fa8125d "=over 8\n\n";
    die q[Can't print ] . $zcc158ad3e0 . ': ' . $! unless print $z5a5f
+a8125d @z6a703c020a;
    print $z5a5fa8125d "=back\n";
    die q[Can't close ] . $zcc158ad3e0 . ': ' . $! unless close *$z5a5
+fa8125d;
    @z8374cc586e = $zcc158ad3e0;
    $z9e5935eea4 = 1;
}
foreach $_ (@z8374cc586e) {
    my $z8348550157 = $_;
    my $zbea0aee021;
    if ($opt_t) {
        'Pod::Text'->z8c2ed69c0e->z4afc07e0ef($z8348550157, $z5da4d383
+7d);
    }
    elsif (not $opt_u) {
        my $z1dfa4cd057 = catfile($z1387c3e117, $z9101bb5154) . (' --l
+ax ' . $z8348550157 . ' | ' . $opt_n . ' -man');
        $z1dfa4cd057 .= ' | col -x' if $^O =~ /hpux/;
        my $z7d70dd4ea9 = `$z1dfa4cd057`;
        $z7d70dd4ea9 = z3d52c17699($z7d70dd4ea9) if $z9e5935eea4;
        unless ($zbea0aee021 = $?) {
            die q[Can't print ] . $zc11e41b4ef . ': ' . $! unless prin
+t $z5da4d3837d $z7d70dd4ea9;
        }
    }
    if ($opt_u or $zbea0aee021) {
        die q[Can't open ] . $z8348550157 . ': ' . $! unless open zf9d
+3fbdfa8, '<', $z8348550157;
        my $z5f7e4d50b8 = 1;
        local $_;
        while (defined($_ = <zf9d3fbdfa8>)) {
            $z5f7e4d50b8 = $1 eq 'cut' if /^=(\w+)/;
            next if $z5f7e4d50b8;
            die q[Can't print ] . $zc11e41b4ef . ': ' . $! unless prin
+t $z5da4d3837d $_;
        }
        die q[Can't close ] . $z8348550157 . ': ' . $! unless close zf
+9d3fbdfa8;
    }
}
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