CHECK_ARGS(sendbuf == nullptr && sendcount > 0, MPI_ERR_BUFFER,
"Iallgather: param 1 sendbuf cannot be NULL when sendcound > 0");
CHECK_ARGS((sendbuf != MPI_IN_PLACE) && (sendtype == MPI_DATATYPE_NULL), MPI_ERR_TYPE,
CHECK_ARGS(sendbuf == nullptr && sendcount > 0, MPI_ERR_BUFFER,
"Iallgather: param 1 sendbuf cannot be NULL when sendcound > 0");
CHECK_ARGS((sendbuf != MPI_IN_PLACE) && (sendtype == MPI_DATATYPE_NULL), MPI_ERR_TYPE,