[mpich-discuss] Extensible Clang type annotation

[Dmitri Gribenko]

[resending to the list, sorry for duplicates]

On Wed, Jan 2, 2013 at 7:31 PM, Dave Goodell <goodell at mcs.anl.gov> wrote:
> [adding Hal Finkel and Dmitri Gribenko, who did most of the annotations work]
>
> Hal/Dmitri,
>
> Do you have any ideas about how to handle Jed's case?  Will the MPICH_ATTR_TYPE_TAG_LAYOUT_COMPATIBLE macro (reproduced below) help in this case?
>
> ----8<----
> #    define MPICH_ATTR_TYPE_TAG_LAYOUT_COMPATIBLE(type)             __attribute__((type_tag_for_datatype(MPI,type,layout_compatible)))
> ----8<----
>
> -Dave
>
> On Dec 30, 2012, at 11:13 PM CST, Jed Brown wrote:
>
>> I upgraded to clang-3.2 and the new type annotations are great. I'd like to have a identified for enum types, e.g.
>>
>> typedef enum {SOME, VALUES} MyEnum;
>> #define MY_MPI_ENUM MPI_INT // or define some other way
>> static const MPI_Datatype my_mpi_enum MPICH_ATTR_TYPE_TAG(MyEnum) = MY_MPI_ENUM;
>>
>>
>> Of course the above does not work because the new definition masks the old one, so all the normal 'int' uses are hidden. Unfortunately, the annotation syntax requires compile-time constants, which are not accessible to me.
>>
>> Is there any hope for something like this, or do I have to choose between (a) ugly cast at all MPI call points and (b) make MY_MPI_ENUM a variable so that the compiler can't check it statically?

Hi everyone,

I don't think we can make it work with the way MPICH currently defines
type tags (MPI_INT etc).  The issue is that these are preprocessor
macros, so in the AST we can only see the values they expand to.  So
MPI_INT and MY_MPI_ENUM become indistinguishable.

But, if you create a different datatype (with MPI_Type_contigous,
probably), it should be possible.

enum MyEnum { Foo };
MPI_Datatype MyEnumDatatype MPICH_ATTR_TYPE_TAG(MyEnum);

int main() {
...
  MPI_Type_contiguous(1, MPI_INT, MyEnumDatatype);
}

I haven't tried it.  Please tell me if it does not work.

Dmitri

-- 
main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
(j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at gmail.com>*/