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remove C wrapper of MPI_Allreduce_scalar #87

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Merged
merged 2 commits into from
Apr 2, 2025
Merged

remove C wrapper of MPI_Allreduce_scalar #87

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3873a4e
remove C wrapper of MPI_Allreduce_scalar
gxyd Apr 2, 2025
44e618f
Handle MPI_IN_PLACE
adit4443ya Apr 2, 2025
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26 changes: 22 additions & 4 deletions src/mpi.f90
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Original file line number Diff line number Diff line change
Expand Up @@ -399,12 +399,30 @@ subroutine MPI_Irecv_proc(buf, count, datatype, source, tag, comm, request, ierr
end subroutine

subroutine MPI_Allreduce_scalar(sendbuf, recvbuf, count, datatype, op, comm, ierror)
use mpi_c_bindings, only: c_mpi_allreduce_scalar
real(8), intent(in) :: sendbuf
real(8), intent(out) :: recvbuf
use iso_c_binding, only: c_int, c_ptr, c_loc
use mpi_c_bindings, only: c_mpi_allreduce_scalar, c_mpi_datatype_f2c, c_mpi_op_f2c, c_mpi_comm_f2c
real(8), intent(in), target :: sendbuf
real(8), intent(out), target :: recvbuf
integer, intent(in) :: count, datatype, op, comm
integer, intent(out), optional :: ierror
call c_mpi_allreduce_scalar(sendbuf, recvbuf, count, datatype, op, comm, ierror)
type(c_ptr) :: sendbuf_ptr, recvbuf_ptr, c_datatype, c_op, c_comm
integer(c_int) :: local_ierr

sendbuf_ptr = c_loc(sendbuf)
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this doesn't handle the case when sendbuf is sent as MPI_IN_PLACE

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this definitely needs handling of MPI_IN_PLACE, without which POT3D will run into an infinite loop.

recvbuf_ptr = c_loc(recvbuf)
c_datatype = c_mpi_datatype_f2c(datatype)
c_op = c_mpi_op_f2c(op)
c_comm = c_mpi_comm_f2c(comm)

local_ierr = c_mpi_allreduce_scalar(sendbuf_ptr, recvbuf_ptr, count, c_datatype, c_op, c_comm)

if (present(ierror)) then
ierror = local_ierr
else
if (local_ierr /= MPI_SUCCESS) then
print *, "MPI_Allreduce_scalar failed with error code: ", local_ierr
end if
end if
end subroutine

subroutine MPI_Allreduce_1d(sendbuf, recvbuf, count, datatype, op, comm, ierror)
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17 changes: 9 additions & 8 deletions src/mpi_c_bindings.f90
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Expand Up @@ -120,14 +120,15 @@ function c_mpi_irecv(buf, count, datatype, source, tag, comm, request) bind(C, n
integer(c_int) :: c_mpi_irecv
end function

subroutine c_mpi_allreduce_scalar(sendbuf, recvbuf, count, datatype, op, comm, ierror) &
bind(C, name="mpi_allreduce_wrapper_real")
use iso_c_binding, only: c_int, c_double
real(c_double), intent(in) :: sendbuf
real(c_double), intent(out) :: recvbuf
integer(c_int), intent(in) :: count, datatype, op, comm
integer(c_int), intent(out), optional :: ierror
end subroutine
function c_mpi_allreduce_scalar(sendbuf, recvbuf, count, datatype, op, comm) &
bind(C, name="MPI_Allreduce")
use iso_c_binding, only: c_int, c_double, c_ptr
type(c_ptr), value :: sendbuf
type(c_ptr), value :: recvbuf
integer(c_int), value :: count
type(c_ptr), value :: datatype, op, comm
integer(c_int) :: c_mpi_allreduce_scalar
end function

subroutine c_mpi_allreduce_1d(sendbuf, recvbuf, count, datatype, op, comm, ierror) &
bind(C, name="mpi_allreduce_wrapper_real")
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