New class for Date objects: caches individual date components.

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index 193f0389da307f2396a33e35cc4b3cef9d80f562..fb258fef40df336d311d52cc571640f24b329043 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -171,7 +171,9 @@ class LCodeGen;
   V(TypeofIsAndBranch)                          \
   V(UnaryMathOperation)                         \
   V(UnknownOSRValue)                            \
-  V(ValueOf)
+  V(ValueOf)                                    \
+  V(DateField)                                  \
+  V(SetDateField)
 
 
 #define DECLARE_CONCRETE_INSTRUCTION(type, mnemonic)              \
@@ -981,6 +983,39 @@ class LValueOf: public LTemplateInstruction<1, 1, 0> {
 };
 
 
+class LDateField: public LTemplateInstruction<1, 1, 0> {
+ public:
+  LDateField(LOperand* date, int index) : index_(index) {
+    inputs_[0] = date;
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(ValueOf, "date-field")
+  DECLARE_HYDROGEN_ACCESSOR(ValueOf)
+
+  int index() const { return index_; }
+
+ private:
+  int index_;
+};
+
+
+class LSetDateField: public LTemplateInstruction<1, 2, 0> {
+ public:
+  LSetDateField(LOperand* date, LOperand* value, int index) : index_(index) {
+    inputs_[0] = date;
+    inputs_[1] = value;
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(DateField, "date-set-field")
+  DECLARE_HYDROGEN_ACCESSOR(DateField)
+
+  int index() const { return index_; }
+
+ private:
+  int index_;
+};
+
+
 class LThrow: public LTemplateInstruction<0, 1, 0> {
  public:
   explicit LThrow(LOperand* value) {