Patching the GCC build system to build MPICH and OpenCoarrays

[Damian Rouson]

On April 3, 2018 at 1:36:37 AM, Richard Biener (richard.guenther@gmail.com) wrote:

You probably only want a new target_module for the MPI library. Note 
it's name has to match that of the directory containing the sources 
which 
as far as I see is 'mpich', not 'libmpi'. 
Thanks!  I’ll ask Daniel to respond if he has further questions.

May I ask again why mpi/opencoarrays should be built together with 
gfortran rather than separately? Does gfortran or any of its current 
target libraries 
link against them? 
Yes, gfortran links to OpenCoarrays via the -fcoarray=lib argument. OpenCoarrays provides the only parallel implementations of gfortran’s Coarray ABI (http://bit.ly/Coarray-ABI). Any Fortran program that uses the large set of parallel features in Fortran 2008 and Fortran 2018 must have OpenCoarrays installed in order for the code to execute in parallel. 

We have found MPICH to be the most robust option and it has the only released support for some of the more advanced requirements such as the Fortran 2018 fault-tolerance features.  However, there will be configure options for using MPI implementations other than MPICH. 


Damian