1 files changed, 18 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/basic/mutable-proto-teleporting.js b/js/src/jit-test/tests/basic/mutable-proto-teleporting.js
new file mode 100644
index 000000000..a52faf1c5
--- /dev/null
+++ b/js/src/jit-test/tests/basic/mutable-proto-teleporting.js
@@ -0,0 +1,18 @@
+// The teleporting optimization should work correctly
+// when we modify an object's proto.
+
+var A = {x: 1};
+var B = Object.create(A);
+
+var C = {};
+C.__proto__ = B;
+
+function f() {
+    for (var i=0; i<25; i++) {
+        assertEq(C.x, (i <= 20) ? 1 : 3);
+        if (i === 20) {
+            B.x = 3;
+        }
+    }
+}
+f();