Hello,

Using MPICH 3.2, I get the following from Valgrind:

==80605== Conditional jump or move depends on uninitialised value(s)

==80605==    at 0x100198C14: MPIC_Waitall (mpiimpl.h:4394)

==80605==    by 0x100061D82: MPI_Dist_graph_create (dist_gr_create.c:380)

==80605==    by 0x100000EC5: main (uninit.c:21)

==80605==  Uninitialised value was created by a stack allocation

==80605==    at 0x100198ADD: MPIC_Waitall (helper_fns.c:735)

When I run this program with 2 ranks:

int main(int argc, char** argv)

{

  MPI_Init(&argc, &argv);

  int n[2] = {1,1};

  int sources[2] = {0,1};

  int degrees[2] = {0,2};

  int destinations_1[2] = {0,1};

  int* destinations[2] = {0, destinations_1};

  int weights_1[2] = {1,1};

  int* weights[2] = {0, weights_1};

  int rank;

  MPI_Comm_rank(MPI_COMM_WORLD, &rank);

  MPI_Comm new_comm;

  MPI_Dist_graph_create(MPI_COMM_WORLD, n[rank], &sources[rank],

      &degrees[rank], destinations[rank], weights[rank],

      MPI_INFO_NULL, 0, &new_comm);

  MPI_Comm_free(&new_comm);

  MPI_Finalize();

}

It seems to come from the status_static_array at

src/mpi/coll/helper_fns.c:740

It looks like status->MPI_SOURCE, when checked by MPIR_Process_status at

src/include/mpiimpl.h:4394

might not be initialized by MPIR_Waitall_impl

(I checked the other things used in that if statement and I'm

pretty sure its MPI_SOURCE).

I had a hard time tracing through the code further than that though.

I just switched from MPICH 3.1.4 and this didn't show up in that version.

I tend to like MPICH for its lack of Valgrind issues,

so let me know how I can help get this fixed.

Thank you,