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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - SLP should recognise return as entry point for vectorisation"
href="https://llvm.org/bugs/show_bug.cgi?id=26773">26773</a>
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<th>Summary</th>
<td>SLP should recognise return as entry point for vectorisation
</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>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
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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>Scalar Optimizations
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>renato.golin@linaro.org
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</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=15957" name="attach_15957" title="Multiplication operator example">attachment 15957</a> <a href="attachment.cgi?id=15957&action=edit" title="Multiplication operator example">[details]</a></span>
Multiplication operator example
As described in #21778, small loops get unrolled early on, which prevents the
loop vectoriser to optimise some small loops with a single call to a SIMD
intrinsic, like the SLP vectorizer does.
The attached code has the two test user functions vectorised by the SLP, but
not the out-of-line copy of the operator*.
I believe the SLP should recognise "return" as an entry point, just as valid as
a store, since functions will be called with either the values in registers on
in the stack, which can utilise the target's PCS standard to connect arguments
in a seamless fashion and avoid *any* unnecessary vector-load/store, or at
least detect the local pattern and have only one vector-load/store, instead of
using the back-end to merge loads/stores.</pre>
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