[CMake] How to compile MPI code

[Michael Wild]

On 06/22/2011 12:00 PM, Mª Dolores Villalobos Ortiz wrote:
> Hi
> 
> I'm trying to compile a main program (it contains MPI functions) using
> cmake. I get an executable file (there aren't problems in compilation ),
> but it doesn't run correctly.
> 
> If I compile my code using a simple Makefile, it works; but I need to
> compile it using cmake (that's a prerequisite for my work).
> 
> I have installed MPICH2 and cmake 2.8.4. and I use the next files:
> 
> CMakeLists.txt:
> 
> cmake_minimum_required(VERSION 2.7)
> set(CMAKE_CXX_COMPILER "/home/lola/Packages/mpich2-1.3.2p1/bin/mpicxx")
> set(CMAKE_C_COMPILER "/home/lola/Packages/mpich2-1.3.2p1/bin/mpicc")
> project( ITK_MPI )
> find_package ( MPI )
> if ( MPI_FOUND )
>         include_directories( ${MPI_INCLUDE_PATH} )
> endif( MPI_FOUND )
> 

This is completely, utterly wrong!


# 2.7 was a development version, so you should either specify
# 2.6 or 2.8...
cmake_minim_required(VERSION 2.7)
project(ITK_MPI)

find_package(MPI REQUIRED)

include_directories(${MPI_INCLUDE_PATH})

add_executable(hello hello.cpp)
target_link_libraries(hello ${MPI_LIBRARIES})

if(MPI_COMPILE_FLAGS)
  set_target_properties(hello PROPERTIES
    COMPILE_FLAGS "${MPI_COMPILE_FLAGS}")
endif()

if(MPI_LINK_FLAGS)
  set_target_properties(hello PROPERTIES
    LINK_FLAGS "${MPI_LINK_FLAGS}")
endif()


You should *NEVER* set CMAKE_<LANG>_COMPILER, this completely breaks
things. Also, with CMake you shouldn't use the compiler wrappers (mpicxx
etc.), because CMake figures out how to compile MPI programs without it.

HTH

Michael