diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/eliminate-unreachable-2.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/eliminate-unreachable-2.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,28 @@
+// Test for one annoying case of the EliminateUnreachableCode
+// optimization.  Here the dominator of print("Goodbye") changes to be
+// the print("Hello") after optimization.
+
+function test1(v) {
+  if (v) {
+    if (v) {
+      assertEq(v, v);
+    } else {
+      assertEq(0, 1);
+    }
+  } else {
+    if (v) {
+      assertEq(0, 1);
+    } else {
+      assertEq(v, v);
+    }
+  }
+  assertEq(v, v);
+}
+
+function test() {
+  test1(true);
+  test1(false);
+}
+
+for (var i = 0; i < 100; i++)
+  test();