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

test/cctest/interpreter/test-bytecode-generator.cc

 // Copyright 2015 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 <fstream>
 
 #include "src/v8.h"
 
 #include "src/interpreter/bytecode-array-iterator.h"
 #include "src/interpreter/bytecode-generator.h"
@@ skipping 1724 matching lines @@
 
       "var ld_a = 1;\n"
       "  ld_a = ld_a + ld_a;\n"
       "  return ld_a;\n",
   };
 
   CHECK(CompareTexts(BuildActual(printer, snippets),
                      LoadGolden("RemoveRedundantLdar.golden")));
 }
 
+TEST(GenerateTestUndetectable) {
+  InitializedIgnitionHandleScope scope;
+  BytecodeExpectationsPrinter printer(CcTest::isolate());
+  const char* snippets[] = {
+      "var obj_a = {val:1};\n"
+      "var b = 10;\n"
+      "if (obj_a == null) { b = 20;}\n"
+      "return b;\n",
+      "var obj_a = {val:1};\n"
+      "var b = 10;\n"
+      "if (obj_a == undefined) { b = 20;}\n"
+      "return b;\n",
+      "var obj_a = {val:1};\n"
+      "var b = 10;\n"
+      "if (obj_a != null) { b = 20;}\n"
+      "return b;\n",
+      "var obj_a = {val:1};\n"
+      "var b = 10;\n"
+      "if (obj_a != undefined) { b = 20;}\n"
+      "return b;\n"};
+
+  CHECK(CompareTexts(BuildActual(printer, snippets),
+                     LoadGolden("GenerateTestUndetectable.golden")));
+}
+
 TEST(AssignmentsInBinaryExpression) {
   InitializedIgnitionHandleScope scope;
   BytecodeExpectationsPrinter printer(CcTest::isolate());
   const char* snippets[] = {
       "var x = 0, y = 1;\n"
       "return (x = 2, y = 3, x = 4, y = 5);\n",
 
       "var x = 55;\n"
       "var y = (x = 100);\n"
       "return y;\n",
@@ skipping 487 matching lines @@
       "foo.f(foo, foo.x);\n",
   };
 
   CHECK(CompareTexts(BuildActual(printer, snippets),
                      LoadGolden("Modules.golden")));
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8