CMake CPU detect

These CMake functions detect the CPU arch for Intel CPUs on Linux, MacOS and Windows. These can be useful for setting -mtune flag for Intel oneAPI. GCC can simply use -mtune=native instead.

Related: CMake project that reveals numerous flags for fine-grained CPU capabilities

Result variables

• HOST_ARCH for Intel CPUs, the generation name e.g. kabylake suitable for -mtune=
• HOST_FLAGS more optimal tuning flags for host system. Sacrifices portability for performance.
• HAS_AVX
• HAS_AVX2
• HAS_NEON

Usage

cmake -B build
cmake --build build

If AVX2 is available, the example can be checked:

cd build
ctest

To use in an actual project, copy DetectHostArch.cmake to your project directory. Then do like the part in if(BUILD_TESTING) in this project's CMakeLists.txt.

Intel oneAPI

Intel oneAPI -xHost or /QxHost is like -march=native -mtune=native on GCC or Clang. Better runtime performance can come from enabling the features of the host CPU.

If you choose to not use -xHost or /QxHost then the mtune option can be used. There is currently no -mtune=native for oneAPI, so this CMake CPU arch detection can help.