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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Optimize 0>=p-q to q >= p for char*p,*q;"
href="http://llvm.org/bugs/show_bug.cgi?id=22065">22065</a>
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<th>Summary</th>
<td>Optimize 0>=p-q to q >= p for char*p,*q;
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>LLVM Codegen
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>llvmbugs@contacts.eelis.net
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>It was noticed that Boost's iterator_facade incurred a performance penalty
(while it should ideally be zero-overhead), which results from the fact that
Clang does not optimize 0>=p-q to q>=p for char*p,*q;. See attachment.
Chandler was reported as saying it's a case of a missing InstCombine rule.
This probably applies to > and < and <= as well.</pre>
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