<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/81488>81488</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            OpenMP runtime assertion failure (barrier on a single thread with target tasks)
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          rpereira-dev
      </td>
    </tr>
</table>

<pre>
    OpenMP runtime assertion failure when executing a barrier on a single thread with target tasks

### main.c
```c
# include <omp.h>
# include <stdlib.h>

# define Nz  8
# define DEVICE_ID  0

int
main(void)
{
    # pragma omp parallel
 {
        # pragma omp single
        {
            # pragma omp target teams distribute parallel for nowait device(DEVICE_ID)
 for (int i = 0 ; i < Nz ; ++i)
                {}
        }
 # pragma omp barrier
    }
    return 0;
}
```

### Command line
```bash
clang -Wall -Werror -Wextra -fopenmp -O0 -g main.c
OMP_NUM_THREADS=1 ./a.out
```

### Output
```
Assertion failure at kmp_runtime.cpp(2460): master_th->th.th_task_team == team->t.t_task_team[master_th->th.th_task_state].
OMP: Error #13: Assertion failure at kmp_runtime.cpp(2460).
```

### Insights
- Using OMP_NUM_THREADS>1 lead to successful termination
- Removing the target tasks lead to successful termination
- Removing the explicit barrier lead to successful termination

I believe this may be related to HHTs
</pre>
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