I am making use of OpenBLAS for both my BLAS and LAPACK routine calls. I do not want the user base of my C++ library to have to install the dependency on their machine. So I want to supply the OpenBLAS library in my third_party and have CMake link to it locally.
The tree
This is the tree of this minimal example project.
OBLASCmake/
├─ third_party/
│ ├─ OpenBLAS-0.3.15
├─ CMakeLists.txt
├─ main.cpp
main.cpp
#include <iostream>
#include <vector>
using namespace std;
extern "C" double ddot_(int *n, double *x, int *incx, double *y, int * incy);
int main() {
int n = 3; // n elements
vector<double> x = {1.2, 2.4, 3.8};
vector<double> y = {4.8, 5.5, 6.2};
int incx = 1; // increments
int incy = 1;
double dot_product = ddot_(&n, &*x.begin(), &incx, &*y.begin(), &incy);
std::cout << dot_product << std::endl;
return 0;
}
CMakeLists (currently)
This goes into the system and looks for the OpenBLAS installation on the users machine. This is not what I want, but it works for me because I have it installed on my machine.
cmake_minimum_required(VERSION 3.19)
project(OBLASCMake)
set(CMAKE_CXX_STANDARD 11)
add_library(OBLASCMake SHARED main.cpp)
set(BLA_VENDOR OpenBLAS)
find_package(BLAS)
if (BLAS_FOUND)
target_link_libraries(OBLASCMake ${BLAS_LIBRARIES})
else()
# ERROR
endif()
add_executable(test1 main.cpp)
target_link_libraries(test1 OBLASCMake)
enable_testing()
add_test(NAME RunTest COMMAND ${CMAKE_BINARY_DIR}/test1)
The result of running the test with this cmake is an output of 42.52 as the dot product of the two vectors.
CMakeLists (what I want)
This method of defining the local installation is not working properly.
cmake_minimum_required(VERSION 3.19)
project(OBLASCMake)
set(CMAKE_CXX_STANDARD 11)
add_library(OBLASCMake SHARED main.cpp)
# cant use add_subdirectory and find_package
# add_subdirectory(third_party/OpenBLAS-0.3.15)
set(OpenBLAS_DIR ${CMAKE_SOURCE_DIR}/third_party/OpenBLAS-0.3.15)
find_package(OpenBLAS REQUIRED HINTS ${CMAKE_SOURCE_DIR}/third_party/OpenBLAS-0.3.15)
add_executable(test1 main.cpp)
target_link_libraries(test1 OBLASCMake)
enable_testing()
add_test(NAME RunTest COMMAND ${CMAKE_BINARY_DIR}/test1)
Building with CMake results in the following error message:
CMake Error at CMakeLists.txt:12 (find_package):
Could not find a package configuration file provided by "OpenBLAS" with any
of the following names:
OpenBLASConfig.cmake
openblas-config.cmake
Add the installation prefix of "OpenBLAS" to CMAKE_PREFIX_PATH or set
"OpenBLAS_DIR" to a directory containing one of the above files. If
"OpenBLAS" provides a separate development package or SDK, be sure it has
been installed.
There is an OpenBLASConfig.cmake file in the third_party/OpenBLAS-0.3.15/, but CMake isn't seeing it. Does anyone know why cmake is unable to see the config file?
Thank you for your time.
