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

src/compiler/js-operator.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/js-operator.h"
 
 #include <limits>
 
 #include "src/base/lazy-instance.h"
 #include "src/compiler/opcodes.h"
@@ skipping 582 matching lines @@
 
 const Operator* JSOperatorBuilder::ToBoolean(ToBooleanHints hints) {
   // TODO(turbofan): Cache most important versions of this operator.
   return new (zone()) Operator1<ToBooleanHints>(  //--
       IrOpcode::kJSToBoolean, Operator::kPure,    // opcode
       "JSToBoolean",                              // name
       1, 0, 0, 1, 0, 0,                           // inputs/outputs
       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) {
   CallFunctionParameters parameters(arity, frequency, feedback, tail_call_mode,
                                     convert_mode);
   return new (zone()) Operator1<CallFunctionParameters>(   // --
       IrOpcode::kJSCallFunction, Operator::kNoProperties,  // opcode
       "JSCallFunction",                                    // name
       parameters.arity(), 1, 1, 1, 1, 2,                   // inputs/outputs
       parameters);                                         // parameter
@@ skipping 287 matching lines @@
   return new (zone()) Operator1<Handle<ScopeInfo>>(               // --
       IrOpcode::kJSCreateScriptContext, Operator::kNoProperties,  // opcode
       "JSCreateScriptContext",                                    // name
       1, 1, 1, 1, 1, 2,                                           // counts
       scpope_info);                                               // parameter
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8