New class for Date objects: caches individual date components.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index b14fa8b34a851065decdce931d56591ef8a64e57..4072e4104f0ac1b815f14777c190593457e02399 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -1217,6 +1217,47 @@ void LCodeGen::DoValueOf(LValueOf* instr) {
 }
 
 
+void LCodeGen::DoDateField(LDateField* instr) {
+  Register input = ToRegister(instr->InputAt(0));
+  Register result = ToRegister(instr->result());
+  ASSERT(input.is(result));
+
+#ifdef DEBUG
+  __ AbortIfSmi(input);
+  __ CmpObjectType(input, JS_DATE_TYPE, kScratchRegister);
+  __ Assert(equal, "Trying to get date field from non-date.");
+#endif
+
+  __ movq(result, FieldOperand(input,
+                      JSDate::kValueOffset + kPointerSize * instr->index()));
+}
+
+
+void LCodeGen::DoSetDateField(LSetDateField* instr) {
+  Register date = ToRegister(instr->InputAt(0));
+  Register value = ToRegister(instr->InputAt(1));
+  Register result = ToRegister(instr->result());
+  int index = instr->index();
+
+#ifdef DEBUG
+  __ AbortIfSmi(date);
+  __ CmpObjectType(date, JS_DATE_TYPE, kScratchRegister);
+  __ Assert(equal, "Trying to get date field from non-date.");
+#endif
+
+  __ movq(FieldOperand(date, JSDate::kValueOffset + kPointerSize * index),
+          value);
+  // Caches can only be smi or NaN, so we can skip the write barrier for them.
+  if (index < JSDate::kFirstBarrierFree) {
+    // Update the write barrier.  Save the value as it will be
+    // overwritten by the write barrier code and is needed afterward.
+    __ movq(result, value);
+    __ RecordWriteField(date, JSDate::kValueOffset + kPointerSize * index,
+                        value, kScratchRegister, kDontSaveFPRegs);
+  }
+}
+
+
 void LCodeGen::DoBitNotI(LBitNotI* instr) {
   LOperand* input = instr->InputAt(0);
   ASSERT(input->Equals(instr->result()));