Fix using monomorphic store instruction for polymorphic stores.

R=jkummerow@chromium.org

Review URL: https://chromiumcodereview.appspot.com/16875008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15214 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen.cc

@@ -6408,7 +6408,8 @@ bool HOptimizedGraphBuilder::TryStorePolymorphicAsMonomorphic(
   AddInstruction(HCheckMaps::New(object, types, zone()));
   HInstruction* store;
   CHECK_ALIVE_OR_RETURN(
-      store = BuildStoreNamedField(object, name, value, types->at(0), &lookup),
+      store = BuildStoreNamedField(
+          object, name, value, types->at(count - 1), &lookup),
       true);
   Push(value);
   store->set_position(expr->position());

test/mjsunit/regress/regress-polymorphic-store.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.
+
+// Flags: --allow-natives-syntax
+
+var o1 = {};
+o1.f1 = function() { return 10; };
+o1.x = 5;
+o1.y = 2;
+var o2 = {};
+o2.x = 5;
+o2.y = 5;
+
+function store(o, v) {
+  o.y = v;
+}
+
+store(o2, 0);
+store(o1, 0);
+store(o2, 0);
+%OptimizeFunctionOnNextCall(store);
+store(o1, 10);
+assertEquals(5, o1.x);
+assertEquals(10, o1.y);