Is there an easy way to use clang with Open MPI?

clang openmpi
Ammar picture Ammar · Jan 22, 2013 · Viewed 8.9k times · Source

OpenMPI strongly recommends using their wrapper compilers. Behind the scenes, their wrapper compiler mpiCC calls gcc (by default?) and adds the necessary flags for MPI code to compile. However, other compilers give more descriptive error messages than gcc (e.g. clang which is also GCC-compatible). So, I'd like to be able to use clang with Open MPI.

I tried:

1) finding an mpiCC option for specifying the compiler, but

mpiCC --help

just spits out the g++ help page.

2) using the --showme:compile option

mpiCC --showme:compile ./test-boost.cc -lboost_mpi -lboost_serialization -o test-boost

which, instead of calling gcc, prints the flags needed for compiling the MPI code. I can then use those with clang (since it's GCC-compatible). This should work, but I'm looking for an easier solution.

Answer

Dmitri Chubarov picture Dmitri Chubarov · Jan 22, 2013

Open MPI FAQ says which environmental variables can be set to override the default choice of the compiler called by the wrapper.

http://www.open-mpi.org/faq/?category=mpi-apps#override-wrappers-after-v1.0

Depending on the version of OpenMPI you should set OMPI_CXX=clang++ or OMPI_MPICC=clang. For OpenMPI v.1.1 and later use OMPI_CXX and then call the wrapper compiler. The wrapper would call clang++ in turn.

Related questions

How to build openmpi with homebrew and gcc-4.9?

By default brew install openmpi uses clang to create its wrapper. I need to specify gcc-4.9(Homebrew installed) for the wrapper. I have tried $export CC=gcc-4.9 $brew install openmpi $brew install --cc=gcc-4.9 openmpi $brew install --with-gcc49 openmpi $brew …

Read More
Why is this program erroneously rejected by three C++ compilers?

I am having some difficulty compiling a C++ program that I've written. This program is very simple and, to the best of my knowledge, conforms to all the rules set forth in the C++ Standard. I've read over the entirety …

Read More
Xcode - ld: library not found for -lPods

I get these errors when I try to build an iOS application. ld: library not found for -lPods clang: error: linker command failed with exit code 1 (use -v to see invocation) Ld /Users/Markus/Library/Developer/Xcode/DerivedData/Totalbox-clpeqwpfvwuhpleeejnzlavncnvj/Build/…

Read More