Bug 489636 - Add a GC u-bench test for property tree splitting via deletion; r=sfink

--HG--
extra : rebase_source : 2e7e21e4a634e348fa584fb1f2514ddffb069a19

js/src/devtools/gc-ubench/benchmarks/propertyTreeSplitting.js

@@ -0,0 +1,25 @@
+window.tests.set('propertyTreeSplitting', (function() {
+var garbage = [];
+var garbageIndex = 0;
+return {
+    description: "use delete to generate Shape garbage",
+    load: (N) => { garbage = new Array(N); },
+    unload: () => { garbage = []; garbageIndex = 0; },
+    makeGarbage: (N) => {
+        function f()
+        {
+            var a1 = eval;
+            delete eval;
+            eval = a1;
+            var a3 = toString;
+            delete toString;
+            toString = a3;
+        }
+        for (var a = 0; a < N; ++a) {
+            garbage[garbageIndex++] = new f();
+            if (garbageIndex == garbage.length)
+                garbageIndex = 0;
+        }
+    }
+};
+})());

js/src/devtools/gc-ubench/index.html

@@ -20,6 +20,7 @@
   <script src="benchmarks/bigTextNodes.js"></script>
   <script src="benchmarks/events.js"></script>
   <script src="benchmarks/expandoEvents.js"></script>
+  <script src="benchmarks/propertyTreeSplitting.js"></script>
 
   <script src="harness.js"></script>