diff -r 000000000000 -r 6474c204b198 js/src/gdb/mozilla/autoload.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/gdb/mozilla/autoload.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,27 @@
+# mozilla/autoload.py: Autoload SpiderMonkey pretty-printers.
+
+print "Loading JavaScript value pretty-printers; see js/src/gdb/README."
+print "If they cause trouble, type: disable pretty-printer .* SpiderMonkey"
+
+import gdb.printing
+import mozilla.prettyprinters
+
+# Import the pretty-printer modules. As a side effect, loading these
+# modules registers their printers with mozilla.prettyprinters.
+import mozilla.jsid
+import mozilla.JSObject
+import mozilla.JSString
+import mozilla.jsval
+import mozilla.Root
+
+# The user may have personal pretty-printers. Get those, too, if they exist.
+try:
+    import my_mozilla_printers
+except ImportError:
+    pass
+
+# Register our pretty-printers with |objfile|.
+def register(objfile):
+    lookup = mozilla.prettyprinters.lookup_for_objfile(objfile)
+    if lookup:
+        gdb.printing.register_pretty_printer(objfile, lookup, replace=True)