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openmpi/ompi/mpi/cxx/info.h
Jeff Squyres 0a28212392 This is a workaround to bug in the Intel C++ compiler, version 9.1
(all versions up to and including 20060925).  The issue has been
reported to Intel, along with a small [non-MPI] test program that
reproduces the problem (the test program and the OMPI C++ bindings
work fine with Intel C++ 9.0 and many other C++ compilers).

In short, a static initializer for a global variable (i.e., its
constructor is fired before main()) that takes as an argument a
reference to a typedef'd type will simply get the wrong value in the
argument.  Specifically:

{{{
namespace MPI {
    Intracomm COMM_WORLD(MPI_COMM_WORLD);
}
}}}

The constructor for MPI::Intracomm should get the value of
&ompi_mpi_comm_world.  It does not; it seems to get a random value.

As mandated by MPI-2, annex B.13.4, for C/C++ interoperability, the
prototype for this constructor is:

{{{
class Intracomm {
public:
    Intracomm(const MPI_Comm& data);
};
}}}

Experiments with icpc 9.1/20060925 have shown that removing the
reference from the prototype makes it work (!).  After lots of
discussions about this issue with a C++ expert (Doug Gregor from IU),
we decided the following (cut-n-paste from an e-mail):

-----
> So here's my question: given that OMPI's MPI_<CLASS> types are all
> pointers, is there any legal MPI program that adheres to the above
> bindings that would fail to compile or work properly if we simply
> removed the "&" from the second binding, above?

I don't know of any way that a program could detect this change. FWIW,
the C++ committee has agreed that implementation of the C++ standard
library are allowed to decide arbitrarily between const& and by-value.
If they don't care, MPI users won't care.

When you remove the '&', I suggest also removing the "const". It is
redundant, but can trigger some strange name mangling in Sun's C++
compiler.
-----

So with this change:

 * we now work again with the Intel 9.1 compiler
 * our C++ bindings do not exactly conform to the MPI-2 spec, but
   valid/legal MPI C++ apps cannot tell the difference (i.e., the
   functionality is the same)

This commit was SVN r12514.
2006-11-09 17:34:12 +00:00

104 строки
2.6 KiB
C++

// -*- c++ -*-
//
// Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
// University Research and Technology
// Corporation. All rights reserved.
// Copyright (c) 2004-2005 The University of Tennessee and The University
// of Tennessee Research Foundation. All rights
// reserved.
// Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
// University of Stuttgart. All rights reserved.
// Copyright (c) 2004-2005 The Regents of the University of California.
// All rights reserved.
// Copyright (c) 2006 Cisco Systems, Inc. All rights reserved.
// $COPYRIGHT$
//
// Additional copyrights may follow
//
// $HEADER$
//
class Info {
#if 0 /* OMPI_ENABLE_MPI_PROFILING */
// friend class PMPI::Info;
#endif
friend class MPI::Comm; //so I can access pmpi_info data member in comm.cc
friend class MPI::Request; //and also from request.cc
public:
#if 0 /* OMPI_ENABLE_MPI_PROFILING */
// construction / destruction
Info() { }
virtual ~Info() {}
// copy / assignment
Info(const Info& data) : pmpi_info(data.pmpi_info) { }
Info(MPI_Info i) : pmpi_info(i) { }
Info& operator=(const Info& data) {
pmpi_info = data.pmpi_info; return *this; }
// comparison, don't need for info
// inter-language operability
Info& operator= (const MPI_Info &i) {
pmpi_info = i; return *this; }
operator MPI_Info () const { return pmpi_info; }
// operator MPI_Info* () const { return pmpi_info; }
operator const PMPI::Info&() const { return pmpi_info; }
#else
Info() { }
// copy
Info(const Info& data) : mpi_info(data.mpi_info) { }
Info(MPI_Info i) : mpi_info(i) { }
virtual ~Info() {}
Info& operator=(const Info& data) {
mpi_info = data.mpi_info; return *this; }
// comparison, don't need for info
// inter-language operability
Info& operator= (const MPI_Info &i) {
mpi_info = i; return *this; }
operator MPI_Info () const { return mpi_info; }
// operator MPI_Info* () const { return (MPI_Info*)&mpi_info; }
#endif
static Info Create();
virtual void Delete(const char* key);
virtual Info Dup() const;
virtual void Free();
virtual bool Get(const char* key, int valuelen, char* value) const;
virtual int Get_nkeys() const;
virtual void Get_nthkey(int n, char* key) const;
virtual bool Get_valuelen(const char* key, int& valuelen) const;
virtual void Set(const char* key, const char* value);
protected:
#if 0 /* OMPI_ENABLE_MPI_PROFILING */
PMPI::Info pmpi_info;
#else
MPI_Info mpi_info;
#endif
};