Re: Patching the GCC build system to build MPICH and OpenCoarrays

[Richard Biener <richard.guenther@gmail.com>]

On Sat, Mar 31, 2018 at 2:44 AM, Damian Rouson
<damian@sourceryinstitute.org> wrote:
> All,
>
> Jerry DeLisle, Daniel Celis Garza, and I would greatly appreciate feedback on our approach to patching the GCC build system to build MPICH and OpenCoarrays after it builds gfortran (gfortran requires MPI and OpenCoarrays to support the parallel features of Fortran 2008 and Fortran 2018).  A diff of our work relative to the GCC trunk is at http://bit.ly/2pQuzvS.  Our steps so far include the following:
>
> 1. Jerry wrote an autotools build system for OpenCoarrays (on the OpenCoarrays issue-343-gnu-build branch.)
> 2. Jerry got MPICH and OpenCoarrays tar balls onto the GCC ftp server.
> 3. I modified GCC’s contrib/download_prerequisites script to download the tar balls.
> 4. Daniel edited GCC’s Makefile.def, config.ac, and Makefile.tpl to incorporate MPICH.
>
> Our current issue is that the Makefile produced as follows doesn’t create the desired “mpi" directory:
>
> git clone -b build-mpich https://github.com/sourceryinstitute/gcc
> mkdir -p gcc/build
> cd gcc/build
> ../configure --disable-bootstrap --enable-languages=fortran
>
> whereupon "grep mpi Makefile” only returns comments and an echo statement.  Ultimately, our desired sequence is to build gfortran, then build MPICH, and then build OpenCoarrays.  All advice is welcome.

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'.

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?

Richard.

> Damian
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