Nvfortran error with function contained in subroutine

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

We’re encountering a compilation error using nvfortran when we try to use functions that are contained within a subroutine, and those contained functions both return arrays and are also called within an OpenMP region.

It’s somewhat specific, here is an example code that demonstrates the problem:

module testmod

    use, intrinsic :: iso_fortran_env

    IMPLICIT NONE

    CONTAINS

     subroutine containingSubroutine()

       real(REAL64) :: vals(4,3)
       integer(INT32) :: i

       !$OMP PARALLEL DO default(shared)
       do i = 1,4
         vals(i,:) = containedFunction()
       end do

       contains

         function containedFunction() result(vecResult)
           real(REAL64), dimension(3) :: vecResult
           vecResult = 0.0_REAL64
         end function containedFunction

     end subroutine containingSubroutine

end module testmod

If I compile that code with this command:

nvfortran -c -mp testmod.F90

Then it generates this error:

error: /glade/u/apps/opt/nvhpc/22.5/Linux_x86_64/22.5/compilers/share/llvm/bin/llc: /glade/scratch/jeffreyg/nefined value '%vecresult'
        %7 = bitcast i64* %vecresult to i8*, !dbg !20
                          ^

There are workarounds such as converting the contained function to a contained subroutine, but it is convenient for us to process some of our large datasets in this way. And it seems as though it may be a bug.

Thanks,
Jeff

2

Thanks Jeff, I was able to reproduce the error and have filed a problem report, TPR #32410.

Looks to be a LLVM code gen error when returning an array from a contained function within an OpenMP region.

-Mat