Fixes scoll_basic failures with shmem_verifier, caused by recent changes
in handling of zero-size collectives.
- Check for zero-size length only for fixed size collect (shmem_fcollect),
but not for variable-size collect (shmem_collect)
- Add 'nlong_type' parameter to internal broadcast function, to indicate
whether the 'nlong' parameter is valid on non-root PEs, since it's
used by shmem_collect algorithm. Before this change, some components
assumed it's true (scoll_mpi) while others assumed it's false
(scoll_basic).
- In scoll_basic, if nlong_type==false, do not exit if nlong==0, since
this parameter may not be the same on all PEs.
- In scoll_mpi, fallback to scoll_basic if nlong_type==false, since MPI
requires the 'count' argument of MPI_Bcast to be valid on all ranks.
(Picked from master 939162e)
Signed-off-by: Yossi Itigin <yosefe@mellanox.com>
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