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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Loop vectorizer does not account for incremented pointers"
href="https://bugs.llvm.org/show_bug.cgi?id=46890">46890</a>
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<th>Summary</th>
<td>Loop vectorizer does not account for incremented pointers
</td>
</tr>
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<th>Product</th>
<td>tools
</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>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>opt
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>joel.hutton@arm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>The following snippet:
void foo(char restrict d, char restrict s1, char* restrict s2) {
for (int y = 0; y < 128; y++) {
for (int i = 0; i < 16; i++) {
d[i] = s1[i] + s2[i];
}
d += 16;
}
}
cannot be vectorized by LLVM trunk, however writing the same snippet in terms
of a constant base pointer (array index i+16*y ) can be vectorized. This
snippet can be vectorized by GCC trunk. Support for this pattern was added to
GCC in GCC 10.
This affects SPEC2017 performance.
Tested on aarch64-linux</pre>
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