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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Loop vectorizer always choose Interleave pattern vs Gather and does not vectorize at the end."
href="https://llvm.org/bugs/show_bug.cgi?id=31426">31426</a>
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<th>Summary</th>
<td>Loop vectorizer always choose Interleave pattern vs Gather and does not vectorize at the end.
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Loop Optimizer
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>elena.demikhovsky@intel.com
</td>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Loop vectorizer cost model for "load" works incorrectly in some cases when the
"load" belongs to an interleave group. If interleaving cost is very high, the
loop is not vectorized. But some targets allows "gather", that makes loop
vectorization profitable. This is the case:
for (i=0; i<N; ++i)
B[i] = A[i*5]
Stride 5 is higher than maxInterleaveFactor supported by Target, and "Gather"
should be taken in this case. But the cost model does not check gathers at all.</pre>
</div>
</p>
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