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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Make sure _Unwind_Exception object is double-word aligned."
href="https://llvm.org/bugs/show_bug.cgi?id=27208">27208</a>
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<th>Summary</th>
<td>Make sure _Unwind_Exception object is double-word aligned.
</td>
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<th>Product</th>
<td>libc++abi
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>All Bugs
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>ahatanak@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
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<th>Classification</th>
<td>Unclassified
</td>
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<p>
<div>
<pre>Itanium C++ ABI states that an _Unwind_Exception object should be double-word
(16B) aligned:
<a href="https://mentorembedded.github.io/cxx-abi/abi-eh.html#base-data">https://mentorembedded.github.io/cxx-abi/abi-eh.html#base-data</a>
However, libc++abi doesn't guarantee it's 16-byte aligned, which caused
programs to crash when __cxa_allocate_exception returned an under-aligned
object.
r264998 fixed clang to lower the expected alignment on Darwin. We should
investigate whether other OSes need similar fixes and whether it's possible to
fix this in libc++abi (instead of in clang) without breaking the ABI.</pre>
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