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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Windows x64 SEH finally filter has handler flags but no LSDA"
href="https://llvm.org/bugs/show_bug.cgi?id=31317">31317</a>
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<th>Summary</th>
<td>Windows x64 SEH finally filter has handler flags but no LSDA
</td>
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<th>Product</th>
<td>new-bugs
</td>
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<th>Version</th>
<td>3.9
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>nb@ravenbrook.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=17740" name="attach_17740" title="Simple example with LLIR and object file dump">attachment 17740</a> <a href="attachment.cgi?id=17740&action=edit" title="Simple example with LLIR and object file dump">[details]</a></span>
Simple example with LLIR and object file dump
When compiling a cleanuppad on Windows x64, the resulting cleanup "filter"
function has UNWIND_INFO with UNWIND_FLAG_EHANDLER and UNWIND_FLAG_UHANDLER
set, but has no room at the end of the UNWIND_INFO for a language-specific data
area. Not even four bytes for a 'count' of zero.
This causes fatal errors if the filter function (or something called by it)
raises an exception.
In our compiler for a client-specific language, we are able to work around this
by identifying UNWIND_INFO blocks without flag bits set but no room for an LSDA
and resetting their flag bits.
See attachment for a detailed example.</pre>
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