You have to pass it an allocated datatype, and it tells you if the pointer
object is a valid MPI datatype for communications (aka it has a
corresponding type with a well defined size, extent and alignment).
There is no construct in C able to tell you if a random number if a valid C
"object".
George.
On Thu, Jun 1, 2017 at 5:42 PM, Dahai Guo <dahai....@gmail.com> wrote:
> Hi,
>
> if I insert following lines somewhere openmpi, such
> as ompi/mpi/c/iscatter.c
>
> printf(" --- in MPI_Iscatter\n");
> //MPI_Datatype dt00 = (MPI_Datatype) MPI_INT;
> *MPI_Datatype dt00 = (MPI_Datatype) -1;*
> if(*!ompi_datatype_is_valid(dt00)* ) {
> printf(" --- dt00 is NOT valid \n");
> }
>
> The attached test code will give the errors:
>
> *** Process received signal ***
> Signal: Segmentation fault (11)
> Signal code: Address not mapped (1)
> Failing at address: 0xf
> [ 0] [0x3fff9d480478]
> ...
>
> Is it a bug in the function *ompi_datatype_is_valid(..) *? or I miss
> something?
>
> Dahai
>
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