1 files changed, 27 insertions, 0 deletions
diff --git a/deps/v8/test/mjsunit/regress/regress-997989.js b/deps/v8/test/mjsunit/regress/regress-997989.js
new file mode 100644
index 0000000000..f049a31724
--- /dev/null
+++ b/deps/v8/test/mjsunit/regress/regress-997989.js
@@ -0,0 +1,27 @@
+// Copyright 2019 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
+
+// A function with a for-in loop, that will be optimized.
+function foo(o) {
+  for (var i in o) {
+    return o[i];
+  }
+}
+
+var o = { x: 0.5 };
+
+// Warm up foo with Double values in the enum cache.
+%PrepareFunctionForOptimization(foo);
+assertEquals(foo(o), 0.5);
+assertEquals(foo(o), 0.5);
+%OptimizeFunctionOnNextCall(foo);
+assertEquals(foo(o), 0.5);
+
+// Transition the double field to a tagged field
+o.x = "abc";
+
+// Make sure that the optimized code correctly loads the tagged field.
+assertEquals(foo(o), "abc");