Cmake Bug
Cmake can not find OpenMP
- Clion(2021.2.2) use the default Cmake version is 3.20.2
-
Got following error at
path-to-build/CMakeFiles/CMakeError.log-- The C compiler identification is MSVC 19.29.30133.0 -- The CXX compiler identification is MSVC 19.29 30133.0 -- Detecting C compiler ABI info -- Detecting C compiler ABI info - failed -- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019/BuildTools/VC Tools/MSVC/14.29.30133/bin/Hostx64/x64/cl.exe -- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019/BuildTools/VC Tools/MSVC/14.29.30133/bin/Hostx64/x64/cl.exe - works -- Detecting C compile features -- Detecting C compile features - done -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - failed -- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019 BuildTools/VC/Tools/MSVC/14.29.30133/bin/Hostx64 x64/cl.exe -- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019 BuildTools/VC/Tools/MSVC/14.29.30133/bin/Hostx64 x64/cl.exe - works -- Detecting CXX compile features -- Detecting CXX compile features - done
-
- After a few tests, I have a status table at below, we can follow this issue
-
PC1[xps] PC2[ucas] clion(cmake 3.20.2) ❌ ✅ cmake 3.21.3 ❌ ✅ cmake 3.19.8 ✅warning(CMAKE_DEPENDS_USE_COMPILER) ✅ - change clion use cmake 3.19.8, the problem has gone
How to use OpenMp
- Need some attention code at CMakeLists.txt
-
CMakeLists.txtFIND_PACKAGE(OpenMP) SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}") - Using
OMP_NUM_THREADS=4at env To Control thread num
Code, A simple example
#include <iostream>
#include <omp.h>
int main() {
int i;
#pragma omp parallel for private(i)
for(i = 0;i<10;i++){
std::cout << "Hello, World!" << i << "\t" <<omp_get_thread_num() << std::endl;
}
return 0;
}
