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feat: Implement wrappers for MPI_Gatherv (#123)
* Add Test for MPI_Gatherv * Add wrappers for MPI_Gatherv
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‎src/mpi.f90

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@@ -72,6 +72,11 @@ module mpi
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module procedure MPI_Allreduce_1D_int_proc
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end interface
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interface MPI_Gatherv
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module procedure MPI_Gatherv_int
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module procedure MPI_Gatherv_real
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end interface MPI_Gatherv
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interface MPI_Wtime
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module procedure MPI_Wtime_proc
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end interface
@@ -765,6 +770,88 @@ subroutine MPI_Recv_StatusIgnore_proc(buf, count, datatype, source, tag, comm, s
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end subroutine MPI_Recv_StatusIgnore_proc
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subroutine MPI_Gatherv_int(sendbuf, sendcount, sendtype, recvbuf, recvcounts, &
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displs, recvtype, root, comm, ierror)
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use iso_c_binding, only: c_int, c_ptr, c_loc
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use mpi_c_bindings, only: c_mpi_gatherv, c_mpi_in_place
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integer, dimension(:), intent(in), target :: sendbuf
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integer, intent(in) :: sendcount
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integer, intent(in) :: sendtype
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integer, dimension(:), intent(out), target :: recvbuf
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integer, dimension(:), intent(in) :: recvcounts
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integer, dimension(:), intent(in) :: displs
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integer, intent(in) :: recvtype
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integer, intent(in) :: root
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integer, intent(in) :: comm
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integer, optional, intent(out) :: ierror
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integer(kind=MPI_HANDLE_KIND) :: c_sendtype, c_recvtype, c_comm
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type(c_ptr) :: c_sendbuf, c_recvbuf
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integer(c_int) :: local_ierr
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if (sendbuf(1) == MPI_IN_PLACE) then
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c_sendbuf = c_MPI_IN_PLACE
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else
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c_sendbuf = c_loc(sendbuf)
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end if
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c_recvbuf = c_loc(recvbuf)
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c_sendtype = handle_mpi_datatype_f2c(sendtype)
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c_recvtype = handle_mpi_datatype_f2c(recvtype)
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c_comm = handle_mpi_comm_f2c(comm)
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! Call C MPI_Gatherv
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local_ierr = c_mpi_gatherv(c_sendbuf, sendcount, c_sendtype, &
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c_recvbuf, recvcounts, displs, c_recvtype, &
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root, c_comm)
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if (present(ierror)) then
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ierror = local_ierr
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else if (local_ierr /= MPI_SUCCESS) then
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print *, "MPI_Gatherv failed with error code: ", local_ierr
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end if
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end subroutine MPI_Gatherv_int
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subroutine MPI_Gatherv_real(sendbuf, sendcount, sendtype, recvbuf, recvcounts, &
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displs, recvtype, root, comm, ierror)
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use iso_c_binding, only: c_int, c_ptr, c_loc
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use mpi_c_bindings, only: c_mpi_gatherv, c_mpi_in_place
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real(8), dimension(:), intent(in), target :: sendbuf
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integer, intent(in) :: sendcount
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integer, intent(in) :: sendtype
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real(8), dimension(:), intent(out), target :: recvbuf
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integer, dimension(:), intent(in) :: recvcounts
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integer, dimension(:), intent(in) :: displs
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integer, intent(in) :: recvtype
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integer, intent(in) :: root
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integer, intent(in) :: comm
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integer, optional, intent(out) :: ierror
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integer(kind=MPI_HANDLE_KIND) :: c_sendtype, c_recvtype, c_comm
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type(c_ptr) :: c_sendbuf, c_recvbuf
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integer(c_int) :: local_ierr
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if (sendbuf(1) == MPI_IN_PLACE) then
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c_sendbuf = c_MPI_IN_PLACE
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else
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c_sendbuf = c_loc(sendbuf)
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end if
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c_recvbuf = c_loc(recvbuf)
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c_sendtype = handle_mpi_datatype_f2c(sendtype)
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c_recvtype = handle_mpi_datatype_f2c(recvtype)
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c_comm = handle_mpi_comm_f2c(comm)
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! Call C MPI_Gatherv
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local_ierr = c_mpi_gatherv(c_sendbuf, sendcount, c_sendtype, &
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c_recvbuf, recvcounts, displs, c_recvtype, &
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root, c_comm)
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if (present(ierror)) then
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ierror = local_ierr
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else if (local_ierr /= MPI_SUCCESS) then
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print *, "MPI_Gatherv failed with error code: ", local_ierr
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end if
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end subroutine MPI_Gatherv_real
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subroutine MPI_Waitall_proc(count, array_of_requests, array_of_statuses, ierror)
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use iso_c_binding, only: c_int, c_ptr
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use mpi_c_bindings, only: c_mpi_waitall, c_mpi_request_f2c, c_mpi_request_c2f, c_mpi_status_c2f, c_mpi_statuses_ignore

‎src/mpi_c_bindings.f90

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@@ -220,6 +220,21 @@ function c_mpi_ssend(buf, count, datatype, dest, tag, comm) bind(C, name="MPI_Ss
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integer(c_int) :: c_mpi_ssend
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end function
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function c_mpi_gatherv(sendbuf, sendcount, sendtype, recvbuf, recvcounts, &
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displs, recvtype, root, comm) bind(C, name="MPI_Gatherv")
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use iso_c_binding, only: c_int, c_ptr
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type(c_ptr), value :: sendbuf
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integer(c_int), value :: sendcount
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integer(kind=MPI_HANDLE_KIND), value :: sendtype
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type(c_ptr), value :: recvbuf
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integer(c_int), dimension(*), intent(in) :: recvcounts
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integer(c_int), dimension(*), intent(in) :: displs
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integer(kind=MPI_HANDLE_KIND), value :: recvtype
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integer(c_int), value :: root
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integer(kind=MPI_HANDLE_KIND), value :: comm
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integer(c_int) :: c_mpi_gatherv
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end function c_mpi_gatherv
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function c_mpi_cart_create(comm_old, ndims, dims, periods, reorder, comm_cart) bind(C, name="MPI_Cart_create")
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use iso_c_binding, only: c_int, c_ptr
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integer(kind=MPI_HANDLE_KIND), value :: comm_old

‎tests/gatherv_1.f90

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@@ -0,0 +1,69 @@
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program gatherv_1
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use mpi
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implicit none
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integer :: ierr, rank, size, root
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integer, allocatable :: sendbuf(:), recvbuf(:)
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integer, allocatable :: recvcounts(:), displs(:)
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integer :: sendcount, i, total
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logical :: error
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! Initialize MPI
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call MPI_Init(ierr)
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call MPI_Comm_rank(MPI_COMM_WORLD, rank, ierr)
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call MPI_Comm_size(MPI_COMM_WORLD, size, ierr)
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! Root process
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root = 0
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! Each process sends 'rank + 1' integers
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sendcount = rank + 1
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allocate(sendbuf(sendcount))
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do i = 1, sendcount
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sendbuf(i) = rank * 100 + i ! Unique values per process
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end do
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! Allocate receive buffers on root
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if (rank == root) then
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allocate(recvcounts(size))
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allocate(displs(size))
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total = 0
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do i = 1, size
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recvcounts(i) = i ! Process i-1 sends i elements
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displs(i) = total ! Displacement in recvbuf
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total = total + recvcounts(i)
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end do
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allocate(recvbuf(total))
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recvbuf = 0
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else
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allocate(recvcounts(1), displs(1), recvbuf(1)) ! Dummy allocations for non-root
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end if
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! Perform gather
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call MPI_Gatherv(sendbuf, sendcount, MPI_INTEGER, recvbuf, recvcounts, &
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displs, MPI_INTEGER, root, MPI_COMM_WORLD, ierr)
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! Verify results on root
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error = .false.
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if (rank == root) then
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do i = 1, size
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do sendcount = 1, i
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if (recvbuf(displs(i) + sendcount) /= (i-1)*100 + sendcount) then
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print *, "Error at rank ", i-1, " index ", sendcount, &
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": expected ", (i-1)*100 + sendcount, &
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", got ", recvbuf(displs(i) + sendcount)
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error = .true.
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error stop
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end if
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end do
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end do
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if (.not. error) then
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print *, "MPI_Gatherv test passed on root"
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end if
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end if
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! Clean up
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deallocate(sendbuf, recvbuf, recvcounts, displs)
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call MPI_Finalize(ierr)
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if (error) stop 1
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end program gatherv_1

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