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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 - [X86] Poor +/-1 integer sign extraction"
href="https://bugs.llvm.org/show_bug.cgi?id=43650">43650</a>
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<th>Summary</th>
<td>[X86] Poor +/-1 integer sign extraction
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
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<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>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>llvm-dev@redking.me.uk
</td>
</tr>
<tr>
<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
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</tr></table>
<p>
<div>
<pre><a href="https://godbolt.org/z/1ZT4eo">https://godbolt.org/z/1ZT4eo</a>
int sign_negone_one(int x)
{
return x < 0 ? -1 : 1;
}
clang:
sign_negone_one:
notl %edi
shrl $31, %edi
leal (%rdi,%rdi), %eax
addl $-1, %eax
retq
vs gcc:
sign_negone_one:
movl %edi, %eax
sarl $31, %eax
orl $1, %eax
ret</pre>
</div>
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