Mark HCompareMap as having Tagged representation

BUG=chromium:346636
LOG=y
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/176923013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19545 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.h

@@ -1617,6 +1617,7 @@ class HCompareMap V8_FINAL : public HUnaryControlInstruction {
       map->AddDependentCompilationInfo(
           DependentCode::kPrototypeCheckGroup, info);
     }
+    set_representation(Representation::Tagged());
   }
 
   int known_successor_index_;

test/mjsunit/regress/regress-crbug-346636.js

@@ -0,0 +1,31 @@
+// Copyright 2014 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 assertSame(expected, found) {
+  if (found === expected) {
+    if (expected !== 0 || (1 / expected) == (1 / found)) return;
+  }
+  return;
+};
+
+function foo(x) {
+  return x.bar;
+}
+
+function getter1() {
+  assertSame(this, this);
+}
+var o1 = Object.defineProperty({}, "bar", { get: getter1 });
+foo(o1);
+foo(o1);
+
+function getter2() {
+  assertSame(this, this);
+}
+var o2 = Object.defineProperty({}, "bar", { get: getter2 });
+foo(o2);
+%OptimizeFunctionOnNextCall(foo);
+foo(o2);