A64: Remove A64 special casing in ExternalCallbackScope

src/vm-state-inl.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 67 matching lines @@
   }
   isolate_->set_current_vm_state(previous_tag_);
 }
 
 
 ExternalCallbackScope::ExternalCallbackScope(Isolate* isolate, Address callback)
     : isolate_(isolate),
       callback_(callback),
       previous_scope_(isolate->external_callback_scope()) {
 #ifdef USE_SIMULATOR
-#if V8_TARGET_ARCH_A64
-  scope_address_ = reinterpret_cast<Address>(Simulator::current(isolate)->sp());
-#else
-  int32_t sp = Simulator::current(isolate)->get_register(Simulator::sp);
-  scope_address_ = reinterpret_cast<Address>(static_cast<intptr_t>(sp));
-#endif
+  scope_address_ = Simulator::current(isolate)->get_sp();
 #endif
   isolate_->set_external_callback_scope(this);
 }
 
 ExternalCallbackScope::~ExternalCallbackScope() {
   isolate_->set_external_callback_scope(previous_scope_);
 }
 
 Address ExternalCallbackScope::scope_address() {
 #ifdef USE_SIMULATOR
   return scope_address_;
 #else
   return reinterpret_cast<Address>(this);
 #endif
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_VM_STATE_INL_H_