[MPIWG Fortran] MPI_SIZEOF: redux

[Jeff Squyres (jsquyres)]

Yep -- looks like it was quoted as being part of F90 incorrectly.

So -- ya: storage_size is F2008 and later.  But I still think it would be ok to deprecate MPI_SIZEOF, since the language now supports this.  And as Bill Long pointed out, having MPI deprecate MPI_SIZEOF might actually pressure compiler vendors to implement storage_size().

And I think we'd give plenty of warning to compiler vendors (i.e., this would be MPI-4).  And also have no plan to actually remove MPI_SIZEOF.


On Jun 6, 2014, at 10:29 AM, Jeff Hammond <jeff.science at gmail.com> wrote:

> Maybe GCC docs are wrong?
> 
> http://gcc.gnu.org/onlinedocs/gfortran/STORAGE_005fSIZE.html
> 
> 8.238 STORAGE_SIZE — Storage size in bits
> 
> 
> Description:
> Returns the storage size of argument A in bits. 
> Standard:
> Fortran 2008 and later 
> Class:
> Inquiry function 
> Syntax:
> RESULT = STORAGE_SIZE(A [, KIND]) 
> Arguments:
> 
> A	Shall be a scalar or array of any type. 
> KIND	(Optional) shall be a scalar integer constant expression. 
> 
> 
> Return Value:
> The result is a scalar integer with the kind type parameter specified by KIND (or default integer type if KIND is missing). The result value is the size expressed in bits for an element of an array that has the dynamic type and type parameters of A. 
> See also:
> C_SIZEOF, SIZEOF
> 
> Sent from my iPhone
> 
> On Jun 6, 2014, at 7:16 AM, "Jeff Squyres (jsquyres)" <jsquyres at cisco.com> wrote:
> 
>> I'm still not sure why you're associating MPI_SIZEOF, F08, and storage_size together...?
>> 
>> According to earlier in the thread, storage_size has been around since F90.  I.e., 20+ years.  
>> 
>> Bill also mentioned that even though some compilers don't yet have it, a) it's easy to implement, and b) giving 2+ years warning to compilers that MPI intends to deprecate MPI_SIZEOF might well give compilers the nudge they need to go implement it.
>> 
>> 
>> 
>> 
>> On Jun 6, 2014, at 9:00 AM, Jeff Hammond <jeff.science at gmail.com> wrote:
>> 
>>> The majority of Fortran users in HPC are ignorant of F08 (beyond trivial notions, eg existence) and will still be by the time of MPI-4. I think deprecating this function must be coincident with deprecating the pre-F08 bindings since it is ootebtionskly required for pre-F08 MPI usage. 
>>> 
>>> If we are serious about forcing everyone to use F08 (which I think is a terrible idea), then let's at least do it consistently.
>>> 
>>> Jeff
>>> 
>>> Sent from my iPhone
>>> 
>>>> On Jun 6, 2014, at 5:15 AM, Bill Long <longb at cray.com> wrote:
>>>> 
>>>> 
>>>>> On Jun 6, 2014, at 6:31 AM, Jeff Squyres (jsquyres) <jsquyres at cisco.com> wrote:
>>>>> 
>>>>> Would it still be ok to deprecate MPI_SIZEOF in MPI-4 (which is at least ~2 years away)?  We don't have to have any plan for removing it.
>>>> 
>>>> I think that would be reasonable.  In two years time more vendors will have implemented storage_size.  And if it were well known that MPI wants people to migrate to this function, vendors would be motivated to add support sooner.  The function itself is pretty trivial to implement as inline code by the compiler.  It’s just a matter of vendor priorities.
>>>> 
>>>> Cheers,
>>>> Bill
>>>> 
>>>> 
>>>> Bill Long                                                                       longb at cray.com
>>>> Fortran Technical Suport  &                                  voice:  651-605-9024
>>>> Bioinformatics Software Development                     fax:  651-605-9142
>>>> Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101
>>>> 
>>>> 
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>> 
>> 
>> -- 
>> 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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-- 
Jeff Squyres
jsquyres at cisco.com
For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/