diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/bug843875.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/bug843875.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,8 @@
+
+function writeHeaderToLog( string ) { }
+var input = [ 0xfffffff0, 101 ];
+var arr = new Uint32Array(input.length);
+var expected = [ 0xffffffff, 101 ];
+for (var i=0; i<arr.length; i++) {
+  arr[i] = writeHeaderToLog[i] = expected[i] = i * 8;
+}