1 files changed, 53 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/basic/megamorphic-setelem-plain.js b/js/src/jit-test/tests/basic/megamorphic-setelem-plain.js
new file mode 100644
index 0000000000..0a60a116e8
--- /dev/null
+++ b/js/src/jit-test/tests/basic/megamorphic-setelem-plain.js
@@ -0,0 +1,53 @@
+setJitCompilerOption("ic.force-megamorphic", 1);
+
+// The megamorphic SetElem.
+function doSet(obj, prop, v) {
+    "use strict";
+    obj[prop] = v;
+}
+function test() {
+    with ({}) {} // No inlining.
+    for (var i = 0; i < 10; i++) {
+        var obj = {};
+
+        // Test simple add/set cases.
+        for (var j = 0; j < 10; j++) {
+            doSet(obj, "x" + (j % 8), j);
+        }
+
+        // Ensure __proto__ is handled correctly.
+        var setterCalls = 0;
+        var proto = {set someSetter(v) { setterCalls++; }};
+        doSet(obj, "__proto__", proto);
+        assertEq(Object.getPrototypeOf(obj), proto);
+
+        // Can't shadow a non-writable data property.
+        Object.defineProperty(proto, "readonly",
+                              {value: 1, writable: false, configurable: true});
+        var ex = null;
+        try {
+            doSet(obj, "readonly", 2);
+        } catch (e) {
+            ex = e;
+        }
+        assertEq(ex instanceof TypeError, true);
+        assertEq(obj.readonly, 1);
+
+        // Setter on the proto chain must be called.
+        doSet(obj, "someSetter", 1);
+        assertEq(setterCalls, 1);
+
+        // Can't add properties if non-extensible.
+        Object.preventExtensions(obj);
+        ex = null;
+        try {
+            doSet(obj, "foo", 1);
+        } catch (e) {
+            ex = e;
+        }
+        assertEq(ex instanceof TypeError, true);
+
+        assertEq(JSON.stringify(obj), '{"x0":8,"x1":9,"x2":2,"x3":3,"x4":4,"x5":5,"x6":6,"x7":7}');
+    }
+}
+test();