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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - r217953 degraded lsr optimization at -O3 for -march=nehalem in SciMark2's Sparse matmult benchmark"
href="http://llvm.org/bugs/show_bug.cgi?id=22640">22640</a>
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<th>Summary</th>
<td>r217953 degraded lsr optimization at -O3 for -march=nehalem in SciMark2's Sparse matmult benchmark
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>3.6
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>howarth.mailing.lists@gmail.com
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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<pre>The SciMark2's Sparse matmult benchmark performance is degraded by up to 24%
after r217953 at -O3 -march=nehalem. The performance regression is reversed by
passing "-mllvm -disable-lsr" to the compiler for the SparseCompRow.c source
file. A diff of the assembly generated for "-O3 -march=nehalem" without and
with "-mllvm -disable-lsr" shows that additional spills are being introduced
by the lsr optimizations.</pre>
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