diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/parallel/Array-buildPar-in-loop.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/parallel/Array-buildPar-in-loop.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,20 @@
+// |jit-test| slow;
+
+load(libdir + "parallelarray-helpers.js")
+
+function buildComprehension() {
+  var pa1 = Array.buildPar(256, function (idx) { return idx; });
+  for (var i = 0; i < 20000; i++) {
+    print(i);
+    buildAndCompare();
+  }
+
+  function buildAndCompare() {
+    // this will be ion-generated:
+    var pa2 = Array.buildPar(256, function (idx) { return idx; });
+    assertStructuralEq(pa1, pa2);
+  }
+}
+
+if (getBuildConfiguration().parallelJS)
+  buildComprehension();