+1
MPI_Datatype is an opaque handler, and in Open MPI, this is an
ompi_datatype_t *
so we can only test for NULL pointers or MPI_DATATYPE_NULL that cannot
be used per the standard.
fwiw, and iirc, MPICH made an other design choice and MPI_Datatype is a
number, so the mpich equivalent of ompi_datatype_is_valid()
might be able to handle random values without crashing.
Cheers,
Gilles
On 6/2/2017 7:36 AM, George Bosilca wrote:
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
<mailto: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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