diff -r 000000000000 -r 6474c204b198 layout/analysis/simple-match.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/analysis/simple-match.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,43 @@
+/* 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/. */
+
+// This executes a very simple search for all functions that call a
+// given set of functions. It's intended to be the simplest possible
+// way of refactoring a common pattern of function calls. Of course,
+// it's still up to a human to decide if the replacement is truely
+// suitable, but this gets the low-hanging fruit.
+
+// Expects the variable 'patterns' to hold an object with replacement
+// function names as keys and function lists as values. Any function
+// in the tested source that calls all of the functions named in the
+// list will be listed in the output as being likely candidates to
+// instead call the replacement function.
+
+include("unstable/lazy_types.js");
+
+var matches = {};
+
+function identity(x) x;
+
+function process_cp_pre_genericize(fndecl)
+{
+    var c = [];
+    function calls(t, stack)
+    {
+        try {
+            t.tree_check(CALL_EXPR);
+            var fn = callable_arg_function_decl(CALL_EXPR_FN(t));
+            if (fn)
+                c.push(decl_name_string(fn));
+        }
+        catch (e if e.TreeCheckError) { }
+    }
+
+    walk_tree(DECL_SAVED_TREE(fndecl), calls);
+
+    for (let [fnreplace, pattern] in patterns)
+        if (pattern.map(function(e){ return c.some(function(f) { return e == f; }); }).every(identity))
+            if (fnreplace != (n = decl_name_string(fndecl)))
+                print(fnreplace +" could probably be used in "+ n);
+}