Nvfortran c_sizeof intrinsic not usable?

Accelerated Computing HPC Compilers nvc, nvc++ and nvfortran
1

Hi,
This small piece of code do not compiles with nvfortran:

program coll

      use iso_c_binding

      implicit none

      integer(c_int), dimension(:,:), allocatable:: tab
      integer :: nx,ny
      integer(kind=8) ::tmax
      integer :: lemax,lemin,i,j

      nx=(huge(nx) -1) /2
      ny=3
      allocate(tab(nx,ny))
      write(6,'(2(a,i0))') "tab is ",size(tab,1)," x ",size(-tab,2)
      tmax=sizeof(tab)
      write(6,'(a,i0)') 'sizeof(tab) is ',tmax
      write(6,'(a,i0)') 'c_sizeof(tab) is ',c_sizeof(tab)

end program coll

The error is:

NVFORTRAN-S-0004-Illegal argument: must be interoperable with a C type  (collapse.f90: 20)
  • tested with nvhpc/24.3 and nvhpc/24.7
  • works with gfortran 14 and Cray cce17

I know sizeof() intrinsic works but it is not part of the fortran standart and I need to ensure some portability of my code. Moreover on Cray compilers the sizeof intrinsic returns only integer*4 values, so not working with large arrays (but again sizeof is not part of fortran standart so I do not intend to use it)

Thanks

2

Hi Patrick,

Thanks for the report. Assumed shape arrays should be allowed for c_sizeof, and if I change the code to pass “tab(:,:)” instead of “tab”, then nvfortran compiles it correctly. Though I think “tab” by itself should work as well so I added a problem report, TPR#36752, and sent it to engineering for intestigation.

The work around works with gfortran 14.2 as well, so might be a good temporary fix. For example:

% cat test.F90
program coll

      use iso_c_binding

      implicit none

      integer(c_int), dimension(:,:), allocatable:: tab
      integer :: nx,ny
      integer(kind=8) ::tmax
      integer :: lemax,lemin,i,j

      nx=(huge(nx) -1) /2
      ny=3
      allocate(tab(nx,ny))
      write(6,'(2(a,i0))') "tab is ",size(tab,1)," x ",size(-tab,2)
      tmax=sizeof(tab)
      write(6,'(a,i0)') 'sizeof(tab) is ',tmax
#ifdef WORKS
      write(6,'(a,i0)') 'c_sizeof(tab) is ',c_sizeof(tab(:,:))
#else
      write(6,'(a,i0)') 'c_sizeof(tab) is ',c_sizeof(tab)
#endif
end program coll
% nvfortran test.F90
NVFORTRAN-S-0004-Illegal argument: must be interoperable with a C type  (test.F90: 21)
  0 inform,   0 warnings,   1 severes, 0 fatal for coll
% nvfortran -DWORKS test.F90
% a.out
tab is 1073741823 x 3
sizeof(tab) is 12884901876
c_sizeof(tab) is 12884901876
% gfortran --version
GNU Fortran (GCC) 14.2.0
Copyright (C) 2024 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

% gfortran test.F90
% a.out
tab is 1073741823 x 3
sizeof(tab) is 12884901876
c_sizeof(tab) is 12884901876
% gfortran -DWORKS test.F90
% a.out
tab is 1073741823 x 3
sizeof(tab) is 12884901876
c_sizeof(tab) is 12884901876

-Mat

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