[MPI3 Fortran] Proposed solution for the volatile buffer problem

Bill Long longb at cray.com
Wed Jan 14 17:48:45 CST 2009

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.



> Aleks

Bill Long                                   longb at cray.com
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