diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/bug848733.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/bug848733.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,11 @@
+var a = [1];
+function f(x) {
+    var round = Math.round;
+    for (var i=0; i<20; i++) {
+	a[0] = round(a[0]);
+	if (x > 500)
+	    a[0] = "a";
+    }
+}
+for (var i=0; i<550; i++)
+    f(i);