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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - redundant direct move instructions generated"
href="https://llvm.org/bugs/show_bug.cgi?id=28117">28117</a>
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</tr>
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<th>Summary</th>
<td>redundant direct move instructions generated
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: PowerPC
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>amehsan@ca.ibm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>This came up in the discussion on <a href="http://reviews.llvm.org/D21135">http://reviews.llvm.org/D21135</a>
for
define double @test2(<2 x i64> %a) {
entry:
%0 = extractelement <2 x i64> %a, i32 0
%1 = sitofp i64 %0 to double
ret double %1
}
we generate
xxswapd 0, 34
mfvsrd 3, 0
mtvsrd 0, 3
xscvsxddp 1, 0
blr
We probably need to look at all users of extractelement in DAGCombine, and make
the right decision before we reach pattern matching. Perhaps peephole
optimization won't work here, as we need information about all users of values
in question.</pre>
</div>
</p>
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