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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - LLVM fails to inline/clone recursive function, leading to 3x slowdown compared to gcc"
href="http://llvm.org/bugs/show_bug.cgi?id=20154">20154</a>
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<th>Summary</th>
<td>LLVM fails to inline/clone recursive function, leading to 3x slowdown compared to gcc
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</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>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Interprocedural Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>rdivacky@freebsd.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=12716" name="attach_12716" title="test case">attachment 12716</a> <a href="attachment.cgi?id=12716&action=edit" title="test case">[details]</a></span>
test case
The attached (big test case) when compiled with trunk clang doesnt have
cpu_search() function inlined (or cloned?) into its callers even when marked
always_inline.
This is because the function is (indirectly) recursive. When compiling the same
file with gcc49, the cpu_search function is inlined.
This file is implementation of scheduler from FreeBSD and as reported
(<a href="https://kib.kiev.ua/kib/pgsql_perf.pdf">https://kib.kiev.ua/kib/pgsql_perf.pdf</a>) inlining it results in massive
improvement in performance (25% -> 8%).</pre>
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