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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Failure to delete dead store"
href="https://bugs.llvm.org/show_bug.cgi?id=35143">35143</a>
</td>
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<tr>
<th>Summary</th>
<td>Failure to delete dead store
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<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>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>chisophugis@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>struct S {
int x[5];
};
S get_S();
void foo() {
S s = get_S();
s.x[5] = 8;
}
<a href="https://godbolt.org/g/QcpRBY">https://godbolt.org/g/QcpRBY</a>
Clang does not delete the store to `s.x[5] = 8`.
Looking at the IR, the pointer out argument passed to get_S seems to be marked
as `sret`. I don't know if that is strong enough to allow inferring `noescape`
on the pointer, but even manually adding `noescape` I don't see that store
being deleted by the O2 pipeline.</pre>
</div>
</p>
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