[Interpreter] Optimize equality check with null/undefined with a check on the map.

src/compiler/js-operator.cc

Index: src/compiler/js-operator.cc
diff --git a/src/compiler/js-operator.cc b/src/compiler/js-operator.cc
index fa55c40837906bdd7924dd36464606f652bb6eee..57d64a2a36a23499a6a884cad7e707a3c0f78c30 100644
--- a/src/compiler/js-operator.cc
+++ b/src/compiler/js-operator.cc
@@ -600,6 +600,14 @@ const Operator* JSOperatorBuilder::ToBoolean(ToBooleanHints hints) {
       hints);                                     // parameter
 }
 
+const Operator* JSOperatorBuilder::IsUndetectable() {
+  // TODO(mythria): Check if we need to cache this operation.
+  return new (zone()) Operator(                      // --
+      IrOpcode::kJSIsUndetectable, Operator::kPure,  // opcode

[mythria, 2016/12/05 10:05:42]

If my understanding is correct, this operation does not throw, does not deopt
and also does not impact effect edges. This operation translates to
ObjectIsUndetectable. 

Also do we need to cache this operator?

+      "JSTestUndetectable",                          // name
+      1, 0, 0, 1, 0, 0);                             // inputs/outputs
+}
+
 const Operator* JSOperatorBuilder::CallFunction(
     size_t arity, float frequency, VectorSlotPair const& feedback,
     ConvertReceiverMode convert_mode, TailCallMode tail_call_mode) {