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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_ASSIGNED "
title="ASSIGNED --- - [ppc] Shorter sequence to load 64bit constant with same hi/lo parts"
href="https://llvm.org/bugs/show_bug.cgi?id=30640">30640</a>
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<th>Summary</th>
<td>[ppc] Shorter sequence to load 64bit constant with same hi/lo parts
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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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>ASSIGNED
</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>Backend: PowerPC
</td>
</tr>
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<th>Assignee</th>
<td>carrot@google.com
</td>
</tr>
<tr>
<th>Reporter</th>
<td>carrot@google.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>Compile following code with options
-m64 -O2 -mvsx -mcpu=power8
unsigned long long foo()
{
return 0xcdcdcdcdcdcdcdcdll;
}
LLVM generats:
# BB#0: # %entry
lis 3, -12851
ori 3, 3, 52685
sldi 3, 3, 32
oris 3, 3, 52685
ori 3, 3, 52685
blr
Because the hi/lo parts are same, we can use rldimi to reduce the code
sequence:
lis 3, -12851
ori 3, 3, 52685
rldimi 3, 3, 32, 0</pre>
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