| Issue |
178790
|
| Summary |
[Flang][OpenMP] Incorrect execution result when parallel construct containing private clause with common block is nested inside parallel construct containing firstprivate clause with common block
|
| Labels |
flang:openmp
|
| Assignees |
|
| Reporter |
ohno-fj
|
```
Version of flang : 23.0.0(e5d235831dfb07b6e767812af7f9d3daa5896f78)/AArch64
```
In the attached program (`snefe018_2.f90`), when `parallel construct` containing `private clause` with `common block (/com/)` is nested inside `parallel construct` containing `firstprivate clause` with `common block (/com/)`, the executi
on result is incorrect.
The execution result is correct in the following cases:
- Remove the inner `parallel construct`
The above is `snefe018_21.f90`.
The following are the test program, Flang, Gfortran and ifx compilation/execution results.
snefe018_2.f90:
```fortran
program main
integer a, b
common /com/ a,b
a=1
b=2
!$omp parallel firstprivate(/com/)
write(6,*) "1 : a = ", a, ", b = ", b
!$omp parallel private(/com/)
!$omp end parallel
!$omp end parallel
write(6,*) "2 : a = ", a, ", b = ", b
end program main
```
```
$ export OMP_NUM_THREADS=2; flang -fopenmp snefe018_2.f90; ./a.out
1 : a = 0 , b = 1025
1 : a = 145721536 , b = 0
2 : a = 1 , b = 2
$
```
```
$ export OMP_NUM_THREADS=2; gfortran -fopenmp snefe018_2.f90; ./a.out
1 : a = 1 , b = 2
1 : a = 1 , b = 2
2 : a = 1 , b = 2
$
```
```
$ export OMP_NUM_THREADS=2; ifx -qopenmp snefe018_2.f90; ./a.out
1 : a = 1 , b = 2
1 : a = 1 , b = 2
2 : a = 1 , b = 2
$
```
snefe018_21.f90:
```fortran
program main
integer a, b
common /com/ a,b
a=1
b=2
!$omp parallel firstprivate(/com/)
write(6,*) "1 : a = ", a, ", b = ", b
! !$omp parallel private(/com/)
! !$omp end parallel
!$omp end parallel
write(6,*) "2 : a = ", a, ", b = ", b
end program main
```
```
$ export OMP_NUM_THREADS=2; flang -fopenmp snefe018_21.f90; ./a.out
1 : a = 1 , b = 2
1 : a = 1 , b = 2
2 : a = 1 , b = 2
$
```
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