Code Generation Differences Across Platforms

Target Hardware Settings

The code generator produces code for the hardware specified by these model configuration parameters:

If you clear Test hardware is the same as production hardware and specify the test device as Custom Processor > MATLAB Host Computer, the code generator targets the current development computer. As a result, when you generate code on a different computer such as a CI pipeline machine, parts of the generated code that depend on the target hardware can differ across machines even when the parameter setting is the same.

For more information about production and test hardware considerations, see Configure Run-Time Environment Options.

Toolchain Settings

The code generator produces code for the toolchain specified by the Toolchain parameter. The default setting, Automatically locate an installed toolchain, selects a toolchain installed on the current computer based on the current MEX compiler settings. This configuration means that even if you do not change this parameter, the selected toolchain can be different when you generate code on a different machine. As a result, parts of the generated code that depend on the toolchain, such as compiler-specific optimizations, can differ across machines even when the parameter setting has not changed.

To mitigate these potential differences, install the same toolchain on the computers that you use to generate code throughout your workflow. For the Toolchain parameter, specify that toolchain instead of automatically locating it.

Data Types

Depending on the data types available from the target platform, the code generator might need to use different data types to implement corresponding Simulink data types. To control how the code generator implements data types, see Manage Replacement of Simulink Data Types in Generated Code.

If data types are different because your test and production hardware have different word sizes, you can configure the code generator to support data types from both platforms by enabling Enable portable word sizes. However, supporting different platform-specific data types generates larger code, specifically, rtwtypes.h, because rtwtypes.h still depends on the current platform. You can avoid generating rtwtypes.h, and instead use data types from the C99 language standard, by setting Data type replacement to Use C data types with fixed-width integers.

Literal Processing

Because different platforms represent and process literals in different ways, literals can appear to be different in the generated code depending on the platform, even if the underlying value is the same. For example, 64-bit integer literals use the suffix LL or ULL on Windows and L or UL on Mac and Linux.

To make generated literals more consistent by using C99 macros for minimum-width integer constants, set Data type replacement to Use C data types with fixed-width integers. (since R2026a)

Multithreading

If the generated code uses multithreading, associated constructs such as mutex and semaphores are platform dependent. You can replace the generated code for a semaphore or mutex with custom implementation code by using code replacement. For more information, see Semaphore and Mutex Function Replacement.

If you generate an example main program and set Target operating system to NativeThreadsExample, the generated main program uses a threading library supported by the current host computer.

Optimizations

Some optimizations are implemented differently in the generated code depending on the platform on which you generate code. For example, vectorized commands for single instruction, multiple data (SIMD) operations depend on the target hardware for which you generate code, so the default value of Leverage target hardware instruction set extensions changes depending on your target hardware.

You can make the generated code more portable and consistent across platforms by disabling platform-specific optimizations; however, the code will be less efficient.

Compiler Implementations of Standard Functions

The compiler defines the implementations for the standard functions that the generated code calls, such as functions from math.h. If the implementation of a function in the specified compiler might cause a numerical mismatch between the generated code and simulation, the code generator replaces the function with a custom implementation. The standard functions that get replaced by custom functions can be different across platforms because of differences in the compiler implementations of the standard functions.

For example, if your toolchain uses the MinGW^® compiler, the code generator replaces the standard C function roundf. To override replacements such as this, use a code replacement library. For more information, see What Is Code Replacement?.