  // is not in a register, but it is on the stack in the marker spill slot.
  LinkageLocation target_loc = is_osr
                                   ? LinkageLocation::ForSavedCallerFunction()
                                   : regloc(kJSFunctionRegister);
  return new (zone) CallDescriptor(     // --
      CallDescriptor::kCallJSFunction,  // kind
      target_type,                      // target MachineType
      target_loc,                       // target location
      types.Build(),                    // machine_sig