CROSS-PLATFORM PITFALLS AND HOW TO AVOID THEM Erika Sweet (she/her) Microsoft C++ TeamWelcome to CppCon 2020! Visit our table at the Expo Hall https://aka.ms/cppcon/expo • Meet the Microsoft C++ include/myTarget PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/src) …and not platform specificUse one toolchain file per target platform…. set(CMAKE_SYSTEM_NAME Linux) set(CMAKE_SYSTEM_PROCESSOR arm) set(CMAKE_C_COMPILER arm-linux-gnueabihf-gcc) set(CMAKE_CXX_COMPILER arm-linux-gnueabihf-g++) …instead of adding logic to your toolchain fileCMake: other resources Daniel Pfeifer: Effective CMake Henry Schreiner & other contributors:

1 (Sort of) 2 3Why FP Determinism is Important?_ CppCon 2024 sixit:: 5 ✅ Same Executable Cross Platform Different Contexts ❌ ❌ 1 (Sort of) 2 3 General Sanity, Testability Distributed when using the identically compiled files and run on systems that adhere to the IEEE standards. Cross platform synchronized network simulations or replays will not possible [sic].” - Most upvoted answer

35-year career in video games and embedded software • Started using C++ in 1995 • First cross-platform project in 1994Cross-Platform Architecture Goals • Take advantage of all platforms • Focus on the compiler implementationThe SIMD Feature in the Build System • Place appropriate feature macro definition in toolchain files: set(PLT_SIMD Common) • In the common project, add the features to the preprocessor definitions: registers, including 4x floats, excluding 2x doublesUpdating the Build System for SSE • Create a new toolchain file • Set the SIMD feature macro: set(PLT_SIMD SSE) • No change is required to the other tool

tools examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 7.4 Cross-building examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . target any existing platform: ranging from bare metal to desktop, mobile, embedded, servers, and cross-building. Conan works with any build system too. There are built-in integrations to support the most pip. This has to run in the same platform that will be using the executable, pyinstaller does not cross-build. The resulting executable can be just copied and put in the system PATH of the running machine

tools examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 7.4 Cross-building examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . target any existing platform: ranging from bare metal to desktop, mobile, embedded, servers, and cross-building. Conan works with any build system too. There are built-in integrations to support the most pip. This has to run in the same platform that will be using the executable, pyinstaller does not cross-build. The resulting executable can be just copied and put in the system PATH of the running machine

tools examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 7.4 Cross-building examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . target any existing platform: ranging from bare metal to desktop, mobile, embedded, servers, and cross-building. Conan works with any build system too. There are built-in integrations to support the most pip. This has to run in the same platform that will be using the executable, pyinstaller does not cross-build. The resulting executable can be just copied and put in the system PATH of the running machine

tools examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 7.4 Cross-building examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . target any existing platform: ranging from bare metal to desktop, mobile, embedded, servers, and cross-building. Conan works with any build system too. There are built-in integrations to support the most pip. This has to run in the same platform that will be using the executable, pyinstaller does not cross-build. The resulting executable can be just copied and put in the system PATH of the running machine

tools examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 7.4 Cross-building examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . target any existing platform: ranging from bare metal to desktop, mobile, embedded, servers, and cross-building. Conan works with any build system too. There are built-in integrations to support the most pip. This has to run in the same platform that will be using the executable, pyinstaller does not cross-build. The resulting executable can be just copied and put in the system PATH of the running machine

tools examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 7.4 Cross-building examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . target any existing platform: ranging from bare metal to desktop, mobile, embedded, servers, and cross-building. Conan works with any build system too. There are built-in integrations to support the most pip. This has to run in the same platform that will be using the executable, pyinstaller does not cross-build. The resulting executable can be just copied and put in the system PATH of the running machine

tools examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 7.4 Cross-building examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . target any existing platform: ranging from bare metal to desktop, mobile, embedded, servers, and cross-building. Conan works with any build system too. There are built-in integrations to support the most pip. This has to run in the same platform that will be using the executable, pyinstaller does not cross-build. The resulting executable can be just copied and put in the system PATH of the running machine