Multiple stubs can point to the same calling convention.

src/ic/ic-conventions.h

 // 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.
 
 #ifndef V8_IC_CONVENTIONS_H_
 #define V8_IC_CONVENTIONS_H_
 
 namespace v8 {
 namespace internal {
 
@@ skipping 40 matching lines @@
   };
   static const Register ReceiverRegister();
   static const Register NameRegister();
   static const Register ValueRegister();
 
   // The map register isn't part of the normal call specification, but
   // ElementsTransitionAndStoreStub, used in polymorphic keyed store
   // stub implementations requires it to be initialized.
   static const Register MapRegister();
 };
+
+
+class InstanceofConvention {
+ public:
+  enum ParameterIndices { kLeftIndex, kRightIndex, kParameterCount };
+  static const Register left();
+  static const Register right();
+};
 }
 }  // namespace v8::internal
 
 #endif  // V8_IC_CONVENTIONS_H_