Optimize the typeof operator.

src/x64/interface-descriptors-x64.cc

 // Copyright 2012 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/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/interface-descriptors.h"
 
@@ skipping 55 matching lines @@
   data->Initialize(arraysize(registers), registers, NULL);
 }
 
 
 void FastNewContextDescriptor::Initialize(CallInterfaceDescriptorData* data) {
   Register registers[] = {rsi, rdi};
   data->Initialize(arraysize(registers), registers, NULL);
 }
 
 
+void TypeofDescriptor::Initialize(CallInterfaceDescriptorData* data) {
+  Register registers[] = {rsi, rbx};
+  data->Initialize(arraysize(registers), registers, NULL);
+}
+
+
 void ToNumberDescriptor::Initialize(CallInterfaceDescriptorData* data) {
   // ToNumberStub invokes a function, and therefore needs a context.
   Register registers[] = {rsi, rax};
   data->Initialize(arraysize(registers), registers, NULL);
 }
 
 
 void NumberToStringDescriptor::Initialize(CallInterfaceDescriptorData* data) {
   Register registers[] = {rsi, rax};
   data->Initialize(arraysize(registers), registers, NULL);
@@ skipping 276 matching lines @@
       Representation::Tagged(),    // call_data
       Representation::Tagged(),    // holder
       Representation::External(),  // api_function_address
   };
   data->Initialize(arraysize(registers), registers, representations);
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64