<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/60737>60737</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Flang][OpenMP] Lower Stop statements in OpenMP regions
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            openmp,
            flang:ir
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          kiranchandramohan
      </td>
    </tr>
</table>

<pre>
    OpenMP standard for Fortran permits `STOP` statements in parallel regions. Currently code with `STOP` statements are not lowered correctly. There could be a few issues here,
1. Flang lowering inserts `fir.unreachable` which is a terminator. It is possible that this is not recognised as a terminator for OpenMP regions.
2. Typically OpenMP lowering code inserts the terminator, and might still insert an `omp.terminator` or `omp.yield`  eventhough a `fir.unreachable` is present.
3. Translation code from MLIR using OpenMPIRBuilder will not handle `llvm.unreachable` if it is the region terminator for OpenMP.

**Reproducer**
```
program mn
   !$omp parallel
      stop 1
   !$omp end parallel
end program
```
</pre>
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