This option is ignored in either of these two cases:

Passing root inputs by value allows this model to read its scalar inputs from register or local memory, which is faster than reading the inputs from their original locations.

Enabling this parameter can result in the simulation behavior differing from the generated code behavior under certain modeling semantics. If you use the default setting ofEnable all as errorsfor theConfiguration Parameters>Diagnostics>Connectivity>Context-dependent inputsparameter, then Simulink^®reports cases where the modeling semantics may result in inconsistent behaviors for simulation and for generated code. If the diagnostic identifies an issue, latch the function-call subsystem inputs. For more information about latching function-call subsystems, seeContext-dependent inputs.

If the Context-dependent inputs diagnostic reports no issues for a model, consider enabling thePass fixed-size scalar root inputs by value for code generationparameter, which usually generates more efficient code for such a model.

If you have aSimulink Coder™license, selecting this option can affect reuse of code generated for subsystems. SeeGenerate Reentrant Code from Subsystems(Simulink Coder) for more information.

For SIM targets, a model that references this model passes inputs by reference, regardless of how you set thePass fixed-size scalar root inputs by value for code generationparameter.