[MPICH] mpich-1.2.7 pgcc and gcc

[Greg Lindahl]

On Wed, Oct 05, 2005 at 08:52:20AM -0500, William Gropp wrote:

> build MPICH with the GNU compilers
> build your application with the appropriate compilers at each site (e.g., 
> use pgf90 for local runs, g95 or gfortran systems without the pg runtime 
> libraries).

Bill,

Note that there are a few additional nits in the Linux world, such as
g77/PathScale using +1 for logical .TRUE., while Intel and PGI use -1.
This got brought up in the ABI discussion a while back, I hadn't heard
about it before then. MPICH has a compile-time method of dealing with
this, but not runtime.

Also, as mentioned recently, gfortran/g95 and g77 have incompatible
means of finding the command-line arguments. It looks like PathScale,
Intel, and PGI are all compatible with the g77 method.

We managed to find a clever way to hack around the first issue so that
our InfiniPath MPICH-based libraries work with multiple compilers at
the same time. The second is also hackable around using some weak
symbols. I suspect it would be useful to get these hacks into MPICH-1
and MPICH-2 so that interconnect vendors would be more likely to
easily support multiple compilers.

-- greg