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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Devirtualization optimization missed"
href="https://bugs.llvm.org/show_bug.cgi?id=37278">37278</a>
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<th>Summary</th>
<td>Devirtualization optimization missed
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>6.0
</td>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>-New Bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>marcosatti@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>The compiler misses this opportunity to perform devirtualization on the
offset/read_uword/write_uword member functions:
<a href="https://godbolt.org/g/P4nfyr">https://godbolt.org/g/P4nfyr</a>
The only compiler to optimize this correctly was GCC where it never calls these
member functions and just uses a register to store the result.
Moving the offset member function directly into the WordPcRegister class makes
the compiler perform the same optimization as GCC.
Marking the WordPcRegister as final or not doesn't seem to make a difference
either.</pre>
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</p>
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