diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/bug731820.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/bug731820.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,29 @@
+function BigInteger(a, b, c) {
+    this.array = new Array();
+    if (a != null) {
+	var this_array = this.array;
+	this.t = 0;
+	var i = a.length;
+	while (--i >= 0) {
+	    this_array[this.t++] = 0;
+	}
+    }
+}
+function bnpCopyTo(r, g) {
+    var this_array = g.array;
+    for (var i = g.t - 1; i >= 0; --i) 
+	r.array[i] = g.array[i];
+    r.t = g.t;
+}
+function montConvert(x) {
+    var r = new BigInteger(null);
+    r.t = 56;
+    return r;
+}
+var ba = new Array();
+a = new BigInteger(ba);
+new BigInteger("afdsafdsafdsaafdsafdsafdsafdsafdsafdsafdsafdsafdsafdsfds");
+g = montConvert(a);
+var r = new BigInteger(null);
+bnpCopyTo(r, g);
+