Improve write barriers in optimized code.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 908faa8011d90142295ee522345fbaf69c0ac181..cdb9756f4e0f894858da4f2d76ddac2123fda219 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -5702,6 +5702,17 @@ inline bool ReceiverObjectNeedsWriteBarrier(HValue* object,
 }
 
 
+inline bool ObjectIsInNewSpace(HValue* object,
+                               HValue* dominator) {
+  while (object->IsInnerAllocatedObject()) {
+    object = HInnerAllocatedObject::cast(object)->base_object();
+  }
+  if (object != dominator) return false;
+  return (object->IsAllocate() &&
+          HAllocate::cast(object)->IsNewSpaceAllocation());
+}
+
+
 class HStoreGlobalCell V8_FINAL : public HUnaryOperation {
  public:
   DECLARE_INSTRUCTION_FACTORY_P3(HStoreGlobalCell, HValue*,
@@ -6720,6 +6731,10 @@ class HStoreNamedField V8_FINAL : public HTemplateInstruction<3> {
     return INLINE_SMI_CHECK;
   }
 
+  bool ValueIsInNewSpace() const {
+    return ObjectIsInNewSpace(value(), new_space_dominator());
+  }
+
   Representation field_representation() const {
     return access_.representation();
   }
@@ -6878,9 +6893,9 @@ class HStoreKeyed V8_FINAL
     return Representation::None();
   }
 
-  HValue* elements() { return OperandAt(0); }
-  HValue* key() { return OperandAt(1); }
-  HValue* value() { return OperandAt(2); }
+  HValue* elements() const { return OperandAt(0); }
+  HValue* key() const { return OperandAt(1); }
+  HValue* value() const { return OperandAt(2); }
   bool value_is_smi() const {
     return IsFastSmiElementsKind(elements_kind_);
   }
@@ -6925,6 +6940,10 @@ class HStoreKeyed V8_FINAL
     }
   }
 
+  bool ValueIsInNewSpace() const {
+    return ObjectIsInNewSpace(value(), new_space_dominator());
+  }
+
   bool NeedsCanonicalization();
 
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;