[MPI3 Fortran] Proposed solution for the volatile buffer problem

[Bill Long]

Aleksandar Donev wrote:
> Bill Long wrote:
>
>> Remember the goal - to prevent code motion across the CALL.  
>> Identifying the CALL, almost by definition, is enough - it is just 
>> overkill.  I covers all variables, including the ones you want to 
>> tag.  The price of simplicity. 
> The price, as Nick tried to explain to you, is that it kills other 
> optimizations *throughout* the code, because the compilers has to 
> assume worst-case scenarios. Not acceptable for a language like 
> Fortran. We cannot trade simplicity for efficiency soo easily!

Yes, except that Nick's argument was complete nonsense.  Vendors have 
known how to do a "suppress" at subroutine boundaries for decades. 

>
>> The optimal solution would be to have both, and preferably use the 
>> same keyword for the attribute and subroutine prefix.
> OK, maybe that has potential.

Agreed.

Cheers,
Bill

>
> Aleks

-- 
Bill Long                                   longb at cray.com
Fortran Technical Support    &              voice: 651-605-9024
Bioinformatics Software Development         fax:   651-605-9142
Cray Inc., 1340 Mendota Heights Rd., Mendota Heights, MN, 55120