New class for Date objects: caches individual date components.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index de6800deb0b61ab43ad55bd68ca1e5616ce4b24f..c926aa65699a76cfb6d9b785e2d9920636c90686 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -179,7 +179,8 @@ class LChunkBuilder;
   V(UnaryMathOperation)                        \
   V(UnknownOSRValue)                           \
   V(UseConst)                                  \
-  V(ValueOf)
+  V(ValueOf)                                   \
+  V(DateField)

[ulan, 2012/01/25 13:08:48]

Don't forget SetDateField.

[rossberg, 2012/01/25 15:48:37]

There was no HSetDateField instruction. ;) However, it exists now.

 
 #define GVN_FLAG_LIST(V)                       \
   V(Calls)                                     \
@@ -4510,6 +4511,26 @@ class HValueOf: public HUnaryOperation {
 };
 
 
+class HDateField: public HUnaryOperation {

[ulan, 2012/01/25 13:08:48]

This instruction has two arguments, so HBinaryOperation or
HTemplateInstruction<2> seem more appropriate.

[rossberg, 2012/01/25 15:48:37]

No, it's a unary instruction. The index is merely a static attribute.

+ public:
+  HDateField(HValue* value, int index)
+    : HUnaryOperation(value), index_(index) {
+    set_representation(Representation::Tagged());

[ulan, 2012/01/25 13:08:48]

Is it possible to use Int32 representation and deoptimize if NaN?

[rossberg, 2012/01/25 15:48:37]

Then I would need to implement the untagging in the instruction. I don't see
what the win would be. The integers cannot be untagged on the object itself.

+  }
+
+  int index() const { return index_; }
+
+  virtual Representation RequiredInputRepresentation(int index) {
+    return Representation::Tagged();
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(DateField)
+
+ private:
+  int index_;
+};
+
+
 class HDeleteProperty: public HBinaryOperation {
  public:
   HDeleteProperty(HValue* context, HValue* obj, HValue* key)