36 lines
1.4 KiB
Markdown
36 lines
1.4 KiB
Markdown
# OpenMP
|
|
|
|
[OpenMP] support was drastically improved in CMake 3.9+. The Modern(TM) way to add OpenMP to a target is:
|
|
|
|
```cmake
|
|
find_package(OpenMP)
|
|
if(OpenMP_CXX_FOUND)
|
|
target_link_libraries(MyTarget PUBLIC OpenMP::OpenMP_CXX)
|
|
endif()
|
|
```
|
|
|
|
This not only is cleaner than the old method, it will also correctly set the library link line differently from the compile line if needed. In CMake 3.12+, this will even support OpenMP on macOS (if the library is available, such as with `brew install libomp`). However, if you need to support older CMake, the following works on CMake 3.1+:
|
|
|
|
```cmake
|
|
# For CMake < 3.9, we need to make the target ourselves
|
|
if(NOT TARGET OpenMP::OpenMP_CXX)
|
|
find_package(Threads REQUIRED)
|
|
add_library(OpenMP::OpenMP_CXX IMPORTED INTERFACE)
|
|
set_property(TARGET OpenMP::OpenMP_CXX
|
|
PROPERTY INTERFACE_COMPILE_OPTIONS ${OpenMP_CXX_FLAGS})
|
|
# Only works if the same flag is passed to the linker; use CMake 3.9+ otherwise (Intel, AppleClang)
|
|
set_property(TARGET OpenMP::OpenMP_CXX
|
|
PROPERTY INTERFACE_LINK_LIBRARIES ${OpenMP_CXX_FLAGS} Threads::Threads)
|
|
|
|
endif()
|
|
target_link_libraries(MyTarget PUBLIC OpenMP::OpenMP_CXX)
|
|
```
|
|
|
|
:::{danger}
|
|
|
|
CMake < 3.4 has a bug in the Threads package that requires you to have the `C` language enabled.
|
|
|
|
:::
|
|
|
|
[openmp]: https://cmake.org/cmake/help/latest/module/FindOpenMP.html
|