[Flang][OpenMP]Incorrect execution result of LASTPRIVATE clause specified in DO construct

[ohno-fj]

Version of flang-new : 17.0.0(3ff080b53b0a7f5bccfabd11254e255669892a67)

LASTPRIVATE clause specified in DO construct does not seem to be valid.

omp_PARALLELDO_005i_2.f:

      program main
      integer*4 ia, ib(50), ier
      integer*4 :: loop=50
      ia = 0
      ib = 0
!$omp parallel do lastprivate(ia)
      do ia=1,loop
         ib(ia) = ia
      enddo
!$omp end parallel do
      write(*,*) "     ia=",ia,"  It must be ",loop+1
      end

$ export OMP_NUM_THREADS=2; flang-new -fopenmp omp_PARALLELDO_005i_2.f; ./a.out
      ia= 50   It must be  51
$

$ export OMP_NUM_THREADS=2; gfortran -fopenmp omp_PARALLELDO_005i_2.f; ./a.out
      ia=          51   It must be           51
$

$ export OMP_NUM_THREADS=2; ifort -qopenmp omp_PARALLELDO_005i_2.f; ./a.out
      ia=          51   It must be           51
$

[llvmbot]

@llvm/issue-subscribers-flang-frontend

[llvmbot]

@llvm/issue-subscribers-openmp

[kiranchandramohan]

The current implementation does not handle the special case of lastprivate of iteration variable.

When the conditional modifier appears on the clause or the list item is an iteration variable of one of the associated loops, if sequential execution of the loop nest would assign a value to the list item then the original list item is assigned the value that the list item would have after sequential execution of the loop nest.

[ohno-fj]

Thank you for your comment.

I understood the current implementation.
I close this issue.

[kiranchandramohan]

Sorry, please keep it open since there is an issue here.

[luporl]

#69773

[llvmbot]

@llvm/issue-subscribers-flang-ir

Author: None (ohno-fj)

``` Version of flang-new : 17.0.0(3ff080b) ```

LASTPRIVATE clause specified in DO construct does not seem to be valid.

omp_PARALLELDO_005i_2.f:

      program main
      integer*4 ia, ib(50), ier
      integer*4 :: loop=50
      ia = 0
      ib = 0
!$omp parallel do lastprivate(ia)
      do ia=1,loop
         ib(ia) = ia
      enddo
!$omp end parallel do
      write(*,*) "     ia=",ia,"  It must be ",loop+1
      end

$ export OMP_NUM_THREADS=2; flang-new -fopenmp omp_PARALLELDO_005i_2.f; ./a.out
      ia= 50   It must be  51
$

$ export OMP_NUM_THREADS=2; gfortran -fopenmp omp_PARALLELDO_005i_2.f; ./a.out
      ia=          51   It must be           51
$

$ export OMP_NUM_THREADS=2; ifort -qopenmp omp_PARALLELDO_005i_2.f; ./a.out
      ia=          51   It must be           51
$