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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_NEW "
title="NEW --- - PowerPC misoptimization for scalar float -> vector float load"
href="https://llvm.org/bugs/show_bug.cgi?id=25157">25157</a>
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<th>Summary</th>
<td>PowerPC misoptimization for scalar float -> vector float load
</td>
</tr>
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<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>3.7
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
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<th>OS</th>
<td>Linux
</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>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>eric.schweitz@pgroup.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>In PPCDAGToDagISel::Select() under the case ISD::VECTOR_SHUFFLE, there is an
optimization to convert a shuffle into a LXVDSX instruction (Load VSX Vector
Doubleword, Splat Indexed). This works great when the values in memory is
actually a doubleword. Unfortunately, it produces incorrect results when the
value is only, say, a word in length and to be converted to a double after the
load.
Here is a possible fix:
@@ -2786,7 +2786,7 @@ SDNode *PPCDAGToDAGISel::Select(SDNode *N) {
LoadSDNode *LD = cast<LoadSDNode>(Op1.getOperand(0));
SDValue Base, Offset;
- if (LD->isUnindexed() &&
+ if (LD->isUnindexed() && LD->getMemoryVT() == MVT::f64 &&
SelectAddrIdxOnly(LD->getBasePtr(), Base, Offset)) {
SDValue Chain = LD->getChain();
SDValue Ops[] = { Base, Offset, Chain };</pre>
</div>
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