remove C wrapper of MPI_Allreduce_scalar

src/mpi.f90

@@ -399,12 +399,34 @@ 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, c_mpi_in_place_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
+
+        if (sendbuf == MPI_IN_PLACE) then
+            sendbuf_ptr = c_mpi_in_place_f2c(sendbuf)
+        else
+            sendbuf_ptr = c_loc(sendbuf)
+        end if
+        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)

src/mpi_c_bindings.f90

@@ -38,6 +38,12 @@ function c_mpi_info_f2c(info_f) bind(C, name="get_c_info_from_fortran")
             type(c_ptr) :: c_mpi_info_f2c
         end function c_mpi_info_f2c
 
+        function c_mpi_in_place_f2c(in_place_f) bind(C,name="get_c_mpi_inplace_from_fortran")
+            use iso_c_binding, only: c_double, c_ptr
+            real(c_double), value :: in_place_f
+            type(c_ptr) :: c_mpi_in_place_f2c
+        end function c_mpi_in_place_f2c
+
         function c_mpi_init(argc, argv) bind(C, name="MPI_Init")
             use iso_c_binding, only : c_int, c_ptr
             !> TODO: is the intent need to be explicitly specified
@@ -120,14 +126,15 @@ 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")

src/mpi_wrapper.c

@@ -57,6 +57,10 @@ MPI_Comm get_c_comm_from_fortran(int comm_f) {
     }
 }
 
+void* get_c_mpi_inplace_from_fortran(double sendbuf) {
+    return MPI_IN_PLACE;
+}
+
 void mpi_allreduce_wrapper_real(const double *sendbuf, double *recvbuf, int *count,
                             int *datatype_f, int *op_f, int *comm_f, int *ierror) {
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);