<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/57648>57648</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            ARM unwind trouble when libcxxabi and friends compiled as Thumb ?
        </td>
    </tr>

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

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

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

<pre>
    I am using libc++abi in embedded system and I have noticed that missing ``.fnstart`` and ``.fnend`` pair prevents proper exception unwind on some occasions (everything is build as Thumb on ARMv7 system). I am not sure whether ``.thumb_func`` makes any difference, but I included this anyway. As far as I remember it resulted in unwinder not being able to find exception descriptor frame for ``__cxa_end_cleanup``. Has anyone else noticed such behaviour ?

https://github.com/llvm/llvm-project/blob/43efb5e445fdd86ab7a0e849b6d70d96d7fafcdc/libcxxabi/src/cxa_exception.cpp#L381
</pre>
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