[Flang][OpenMP] Incorrect execution result of a do-variable in critical construct which exists in parallel construct with default(none) clause

[ohno-fj]

Version of flang-new : 18.0.0(0fe86f9c518fb1296bba8d66ce495f9dfff2c435)

If critical construct exists in parallel construct with default(none) clause, a do-variable has an incorrect value after executing parallel construct.
A do-variable is private according to the specification in Section (2.15.1.1) of OpenMP 4.5, so the values of k1 and k2 are expected to be 1.
Changing critical construct to sections construct has the same result.

The following are the test program, Flang-new, Gfortran and ifort compilation/execution result.

snfm_omp_array_do_011.f90:

program main
  integer::k1,k2
  k1=1; k2=1
!$omp parallel default(none)
!$omp critical
  do k2=1,10
     do k1=1,10
     end do
  end do
!$omp end critical
!$omp endparallel
  write(6,*) "k1 = ", k1, " k2 = ", k2
end program main

$ export OMP_NUM_THREADS=2; flang-new -fopenmp snfm_omp_shared_13_011.f90; ./a.out
 k1 =  11  k2 =  11
$

$ export OMP_NUM_THREADS=2; gfortran -fopenmp snfm_omp_array_do_011.f90; ./a.out
 k1 =            1  k2 =            1
$

$ export OMP_NUM_THREADS=2; ifort -qopenmp snfm_omp_array_do_011.f90; ./a.out
 k1 =            1  k2 =            1
$

[llvmbot]

@llvm/issue-subscribers-openmp

Author: None (ohno-fj)

``` Version of flang-new : 18.0.0(0fe86f9) ```

If critical construct exists in parallel construct with default(none) clause, a do-variable has an incorrect value after executing parallel construct.
A do-variable is private according to the specification in Section (2.15.1.1) of OpenMP 4.5, so the values of k1 and k2 are expected to be 1.
Changing critical construct to sections construct has the same result.

The following are the test program, Flang-new, Gfortran and ifort compilation/execution result.

snfm_omp_array_do_011.f90:

program main
  integer::k1,k2
  k1=1; k2=1
!$omp parallel default(none)
!$omp critical
  do k2=1,10
     do k1=1,10
     end do
  end do
!$omp end critical
!$omp endparallel
  write(6,*) "k1 = ", k1, " k2 = ", k2
end program main

$ export OMP_NUM_THREADS=2; flang-new -fopenmp snfm_omp_shared_13_011.f90; ./a.out
 k1 =  11  k2 =  11
$

$ export OMP_NUM_THREADS=2; gfortran -fopenmp snfm_omp_array_do_011.f90; ./a.out
 k1 =            1  k2 =            1
$

$ export OMP_NUM_THREADS=2; ifort -qopenmp snfm_omp_array_do_011.f90; ./a.out
 k1 =            1  k2 =            1
$

[luporl]

This is similar to #75767.
But predetermined loop iteration variables for a sequential loop in a parallel construct are handled by OmpAttributeVisitor::Pre(const parser::DoConstruct &x) instead, that also checks for !dirContext_.empty() && GetContext().withinConstruct, which evaluates to false with the test program.

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: None (ohno-fj)

``` Version of flang-new : 18.0.0(0fe86f9) ```

If critical construct exists in parallel construct with default(none) clause, a do-variable has an incorrect value after executing parallel construct.
A do-variable is private according to the specification in Section (2.15.1.1) of OpenMP 4.5, so the values of k1 and k2 are expected to be 1.
Changing critical construct to sections construct has the same result.

The following are the test program, Flang-new, Gfortran and ifort compilation/execution result.

snfm_omp_array_do_011.f90:

program main
  integer::k1,k2
  k1=1; k2=1
!$omp parallel default(none)
!$omp critical
  do k2=1,10
     do k1=1,10
     end do
  end do
!$omp end critical
!$omp endparallel
  write(6,*) "k1 = ", k1, " k2 = ", k2
end program main

$ export OMP_NUM_THREADS=2; flang-new -fopenmp snfm_omp_shared_13_011.f90; ./a.out
 k1 =  11  k2 =  11
$

$ export OMP_NUM_THREADS=2; gfortran -fopenmp snfm_omp_array_do_011.f90; ./a.out
 k1 =            1  k2 =            1
$

$ export OMP_NUM_THREADS=2; ifort -qopenmp snfm_omp_array_do_011.f90; ./a.out
 k1 =            1  k2 =            1
$