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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Failure to optimize followed xors into seperate xors to avoid mov"
href="https://bugs.llvm.org/show_bug.cgi?id=45774">45774</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Failure to optimize followed xors into seperate xors to avoid mov
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>gabravier@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>int f(int x, int y, int c)
{
return (x - y - c) ^ x ^ y;
}
With -O3, GCC outputs this :
f:
mov eax, edi
xor edi, esi
sub eax, esi
sub eax, edx
xor eax, edi
ret
Clang outputs this :
f:
mov eax, esi
mov ecx, edi
sub ecx, esi
sub ecx, edx
xor eax, edi
xor eax, ecx
ret</pre>
</div>
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