diff -r 000000000000 -r 6474c204b198 tools/reorder/missing-syms.pl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/reorder/missing-syms.pl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,36 @@
+#!/usr/bin/perl -w
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# List the missing symbols (or, do a set difference).
+#
+
+use 5.004;
+use strict;
+use Getopt::Long;
+
+$::opt_help = 0;
+$::opt_defined = "mozilla-bin.order";
+GetOptions("help", "defined=s");
+
+if ($::opt_help) {
+    die "usage: missing-syms.pl --defined=<file> <symlist>";
+}
+
+$::Defined = { };
+
+open(DEFINED, "<$::opt_defined") || die "couldn't open defined symbol list $::opt_defined";
+while (<DEFINED>) {
+    chomp;
+    $::Defined{$_} = 1;
+}
+close(DEFINED);
+
+while (<>) {
+    chomp;
+    print "$_\n" unless ($::Defined{$_});
+}
+