[Interpreter] Transform StrictEquality with null/undefined to special bytecodes.

src/interpreter/mkpeephole.cc

 // Copyright 2016 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 <array>
 #include <fstream>
 #include <map>
 #include <string>
 #include <vector>
 
@@ skipping 177 matching lines @@
             PeepholeAction::kTransformLdaZeroBinaryOpToBinaryOpWithZeroAction,
             Bytecode::kShiftRightSmi};
       default:
         break;
     }
   }
 
   // Fuse LdaNull/LdaUndefined followed by a equality comparison with test
   // undetectable. Testing undetectable is a simple check on the map which is
   // more efficient than the full comparison operation.
-  // Note: StrictEquals cannot use this, they need to compare it with the
-  // Null/undefined map.
   if (last == Bytecode::kLdaNull || last == Bytecode::kLdaUndefined) {
     if (current == Bytecode::kTestEqual) {
-      return {PeepholeAction::
-                  kTransformEqualityWithNullOrUndefinedToTestUndetectableAction,
-              Bytecode::kIllegal};
+      return {PeepholeAction::kTransformEqualityWithNullOrUndefinedAction,
+              Bytecode::kTestUndetectable};
     }
   }
 
+  // Fuse LdaNull/LdaUndefined followed by a strict equals with
+  // TestNull/TestUndefined.
+  if (current == Bytecode::kTestEqualStrict) {
+    if (last == Bytecode::kLdaNull) {
+      return {PeepholeAction::kTransformEqualityWithNullOrUndefinedAction,
+              Bytecode::kTestNull};
+    } else if (last == Bytecode::kLdaUndefined) {
+      return {PeepholeAction::kTransformEqualityWithNullOrUndefinedAction,
+              Bytecode::kTestUndefined};
+    }
+  }
+
   // If there is no last bytecode to optimize against, store the incoming
   // bytecode or for jumps emit incoming bytecode immediately.
   if (last == Bytecode::kIllegal) {
     if (Bytecodes::IsJump(current)) {
       return {PeepholeAction::kUpdateLastJumpAction, Bytecode::kIllegal};
     } else if (current == Bytecode::kNop) {
       return {PeepholeAction::kUpdateLastIfSourceInfoPresentAction,
               Bytecode::kIllegal};
     } else {
       return {PeepholeAction::kUpdateLastAction, Bytecode::kIllegal};
@@ skipping 145 matching lines @@
 
   std::ofstream ofs(argv[1], std::ofstream::trunc);
   v8::internal::interpreter::PeepholeActionTableWriter writer;
   writer.BuildTable();
   writer.Write(ofs);
   ofs.flush();
   ofs.close();
 
   return 0;
 }