Fix re-initialization of existing double field.

R=verwaest@chromium.org
BUG=v8:2717
TEST=mjsunit/regress/regress-2717

Review URL: https://codereview.chromium.org/16735003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15033 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -4026,6 +4026,7 @@ MaybeObject* JSObject::SetLocalPropertyIgnoreAttributes(
       Representation representation = lookup.representation();
       Representation value_representation =
           value->OptimalRepresentation(value_type);
+      if (value_representation.IsNone()) break;
       if (!value_representation.fits_into(representation)) {
         MaybeObject* maybe_failure = self->GeneralizeFieldRepresentation(
             lookup.GetDescriptorIndex(), value_representation);

test/mjsunit/regress/regress-2717.js

+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Test re-initializing existing field which is already being tracked as
+// having double representation.
+(function() {
+  function test1(a) {
+    return { x: 1.5, x: a };
+  };
+
+  assertEquals({}, test1({}).x);
+})();
+
+// Test initializing new field which follows an existing transition to a
+// map that tracks it as having double representation.
+(function() {
+  function test1(a) {
+    return { y: a };
+  };
+
+  function test2(a) {
+    return { y: a };
+  };
+
+  assertEquals(1.5, test1(1.5).y);
+  assertEquals({}, test2({}).y);
+})();