[MPIWG Fortran] Another MPI_SIZEOF question

[Rolf Rabenseifner]

> As far as I can tell from the
> requirement that MPI_SIZEOF be supported, mpif.h also requires
> Fortran 2008 + TS29113, meaning that many legacy MPI programs cannot
> be compiled with a standard conforming MPI implementation and a
> Fortran compiler that implements only, say, Fortran 2008 (but not
> the TS29113, which is *not* part of the standard) or Fortran 2003.

Section 17.1.6 on page 609 "MPI for Different Fortran Standard Versions"
tries to define the rules for standard compliant MPI-3.0 with 
a Fortran 77, 90, 95, 2003, and 2003/2008+TS29113 compiler,
i.e., MPI-3.0 can be implemented with the restrictions, 
e.g., MPI_SUBARRAYS_SUPPORTED needs to be set to .FALSE..

Rolf 
  


----- Original Message -----
> From: "William Gropp" <wgropp at illinois.edu>
> To: "MPI-WG Fortran working group" <mpiwg-fortran at lists.mpi-forum.org>
> Sent: Tuesday, June 10, 2014 3:06:08 PM
> Subject: Re: [MPIWG Fortran] Another MPI_SIZEOF question
> 
> 
> This naming corresponds to MPI-3 but not to the use in MPI-1 nor to
> what some users may still want, which is what Jeff is talking about.
>  
> 
> 
> And note: When the original MPI Fortran interface was defined, it was
> known not to be standard conformant - in fact, I raised that issue
> and raised a straw man alternative that was not accepted by the MPI
> Forum.  The fact at the time was that it was widely recognized that
> Fortran's (meaning Fortran 77) strict rules with the absence of any
> escape combined with no real general data mechanism, needed by many
> different libraries, not just MPI, made the type checking rules
> impractical, and virtually no compiler of the time implemented this
> check (the only one I knew of was WATFOR, and you could turn it
> off). 
> 
> 
> Despite this, many applications were written using Fortran.  Those
> applications in practice, despite not conforming to the letter of
> the standard, were portable and contributed to the success of MPI.
>  I don't find comments about "MPI never supported Fortran" to be
> useful, even if they are technically true.
> 
> 
> In my opinion, the use of "mpif.h" should have been to support
> existing programs in their existing compilation environments.  That
> might be fixed-format early Fortran, either Fortran 77 or perhaps
> Fortran 90 or Fortran 95. The goal of MPI-3 should have been to
> ensure that new programs used the mpi or mpi_f08 modules and that
> existing programs could continue to be used.  That is *not* the
> situation that we have now.   As far as I can tell from the
> requirement that MPI_SIZEOF be supported, mpif.h also requires
> Fortran 2008 + TS29113, meaning that many legacy MPI programs cannot
> be compiled with a standard conforming MPI implementation and a
> Fortran compiler that implements only, say, Fortran 2008 (but not
> the TS29113, which is *not* part of the standard) or Fortran 2003.  
> 
> 
> Bill
> 
> 
> 
> 
> 
> 
> William Gropp
> Director, Parallel Computing Institute Thomas M. Siebel Chair in
> Computer Science
> 
> 
> University of Illinois Urbana-Champaign
> 
> 
> 
> 
> 
> 
> 
> On Jun 10, 2014, at 2:44 PM, Jeff Squyres (jsquyres) wrote:
> 
> 
> 
> On Jun 10, 2014, at 8:35 AM, Jeff Hammond < jeff.science at gmail.com >
> wrote:
> 
> 
> 
> What shorthand will you permit for what is meant when Bill and I
> refer
> 
> 
> to Fortran 77 support in MPI that distinguishes it from F90 and F08
> 
> 
> module support?
> 
> I usually say "the mpif.h interface", "the (Fortran) mpi module", and
> "the mpi_f08 module".  Indeed, I have renamed the "ompi/mpi/f77" and
> "ompi/mpi/f90" directories from previous versions of OMPI to
> "ompi/mpi/fortran/mpifh" and "ompi/mpi/fortran/use-mpi".  
> 
> Meaning: I have seen the error of my ways and corrected myself.  You
> can, too.  :-)
> 
> --
> Jeff Squyres
> jsquyres at cisco.com
> For corporate legal information go to:
> http://www.cisco.com/web/about/doing_business/legal/cri/
> 
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> 
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-- 
Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room 1.307)