Fix HConstants with Smi-ranged HeapNumber values

BUG=chromium:349878
LOG=y
R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/186123003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19693 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -2562,7 +2562,11 @@ HConstant::HConstant(int32_t integer_value,
     boolean_value_(integer_value != 0),
     int32_value_(integer_value),
     double_value_(FastI2D(integer_value)) {
-  set_type(has_smi_value_ ? HType::Smi() : HType::TaggedNumber());
+  // It's possible to create a constant with a value in Smi-range but stored
+  // in a (pre-existing) HeapNumber. See crbug.com/349878.
+  bool could_be_heapobject = r.IsTagged() && !object.handle().is_null();
+  bool is_smi = has_smi_value_ && !could_be_heapobject;
+  set_type(is_smi ? HType::Smi() : HType::TaggedNumber());
   Initialize(r);
 }
 
@@ -2582,7 +2586,11 @@ HConstant::HConstant(double double_value,
     int32_value_(DoubleToInt32(double_value)),
     double_value_(double_value) {
   has_smi_value_ = has_int32_value_ && Smi::IsValid(int32_value_);
-  set_type(has_smi_value_ ? HType::Smi() : HType::TaggedNumber());
+  // It's possible to create a constant with a value in Smi-range but stored
+  // in a (pre-existing) HeapNumber. See crbug.com/349878.
+  bool could_be_heapobject = r.IsTagged() && !object.handle().is_null();
+  bool is_smi = has_smi_value_ && !could_be_heapobject;
+  set_type(is_smi ? HType::Smi() : HType::TaggedNumber());
   Initialize(r);
 }
 

test/mjsunit/regress/regress-crbug-349878.js

+// 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 f(a, b) {
+  a == b;
+}
+
+f({}, {});
+
+var a = { y: 1.5 };
+a.y = 777;
+var b = a.y;
+
+function h() {
+  var d = 1;
+  var e = 777;
+  while (d-- > 0) e++;
+  f(1, e);
+}
+
+var global;
+function g() {
+  global = b;
+  return h(b);
+}
+
+g();
+g();
+%OptimizeFunctionOnNextCall(g);
+g();