Crankshaft: consolidated element loads always deopted on seeing the hole

test/mjsunit/regress/regress-4380.js

Index: test/mjsunit/regress/regress-4380.js
diff --git a/test/mjsunit/regress/regress-4380.js b/test/mjsunit/regress/regress-4380.js
new file mode 100644
index 0000000000000000000000000000000000000000..8a83def6e29e3357a8e3fdc5f3991fc8282b5596
--- /dev/null
+++ b/test/mjsunit/regress/regress-4380.js
@@ -0,0 +1,20 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+function bar(a) {
+  var x = a[0];
+  return x == undefined;
+}
+
+// Make the keyed load be polymorphic on holey smi and holey fast.
+bar([, 2, 3]);
+bar([, 'two', 'three']);
+bar([, 2, 3]);
+
+%OptimizeFunctionOnNextCall(bar);
+bar([, 2, 3]);
+// Verify that loading the hole doesn't cause deoptimization.
+assertOptimized(bar);