[turbofan] Initial support for the %_DateField intrinsic.

src/compiler/js-intrinsic-lowering.cc

Index: src/compiler/js-intrinsic-lowering.cc
diff --git a/src/compiler/js-intrinsic-lowering.cc b/src/compiler/js-intrinsic-lowering.cc
index b679a75fab7ab2a188e27c6b1f001af9f5324aaf..891e17fb3715fb46784e18922d33fa74fe0f4702 100644
--- a/src/compiler/js-intrinsic-lowering.cc
+++ b/src/compiler/js-intrinsic-lowering.cc
@@ -32,6 +32,8 @@ Reduction JSIntrinsicLowering::Reduce(Node* node) {
   switch (f->function_id) {
     case Runtime::kInlineConstructDouble:
       return ReduceConstructDouble(node);
+    case Runtime::kInlineDateField:
+      return ReduceDateField(node);
     case Runtime::kInlineDeoptimizeNow:
       return ReduceDeoptimizeNow(node);
     case Runtime::kInlineDoubleHi:
@@ -106,6 +108,24 @@ Reduction JSIntrinsicLowering::ReduceConstructDouble(Node* node) {
 }
 
 
+Reduction JSIntrinsicLowering::ReduceDateField(Node* node) {
+  Node* const value = NodeProperties::GetValueInput(node, 0);
+  Node* const index = NodeProperties::GetValueInput(node, 1);
+  Node* const effect = NodeProperties::GetEffectInput(node);
+  Node* const control = NodeProperties::GetControlInput(node);
+  NumberMatcher mindex(index);
+  if (mindex.Is(JSDate::kDateValue)) {
+    return Change(
+        node,
+        simplified()->LoadField(AccessBuilder::ForJSDateField(
+            static_cast<JSDate::FieldIndex>(static_cast<int>(mindex.Value())))),
+        value, effect, control);
+  }
+  // TODO(turbofan): Optimize more patterns.
+  return NoChange();
+}
+
+
 Reduction JSIntrinsicLowering::ReduceDeoptimizeNow(Node* node) {
   if (mode() != kDeoptimizationEnabled) return NoChange();
   Node* frame_state = NodeProperties::GetFrameStateInput(node, 0);