[turbofan] Introduce dedicated ObjectIsNaN operator.

src/compiler/js-typed-lowering.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-typed-lowering.h"
 
 #include "src/ast/modules.h"
 #include "src/builtins/builtins-utils.h"
 #include "src/code-factory.h"
 #include "src/compilation-dependencies.h"
@@ skipping 975 matching lines @@
     r.CheckInputsToString();
     return r.ChangeToPureOperator(simplified()->StringEqual(), invert);
   }
   return NoChange();
 }
 
 Reduction JSTypedLowering::ReduceJSStrictEqual(Node* node, bool invert) {
   JSBinopReduction r(this, node);
   if (r.left() == r.right()) {
     // x === x is always true if x != NaN
-    if (!r.left_type()->Maybe(Type::NaN())) {
-      Node* replacement = jsgraph()->BooleanConstant(!invert);
-      ReplaceWithValue(node, replacement);
-      return Replace(replacement);
+    Node* replacement = graph()->NewNode(simplified()->ObjectIsNaN(), r.left());
+    if (!invert) {
+      replacement = graph()->NewNode(simplified()->BooleanNot(), replacement);
     }
+    ReplaceWithValue(node, replacement);
+    return Replace(replacement);
   }
   if (r.OneInputCannotBe(Type::NumberOrString())) {
     // For values with canonical representation (i.e. neither String, nor
     // Number) an empty type intersection means the values cannot be strictly
     // equal.
     if (!r.left_type()->Maybe(r.right_type())) {
       Node* replacement = jsgraph()->BooleanConstant(invert);
       ReplaceWithValue(node, replacement);
       return Replace(replacement);
     }
@@ skipping 1479 matching lines @@
 }
 
 
 CompilationDependencies* JSTypedLowering::dependencies() const {
   return dependencies_;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8