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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - thread_local variables are not aligned properly on NetBSD"
href="https://bugs.llvm.org/show_bug.cgi?id=40120">40120</a>
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<th>Summary</th>
<td>thread_local variables are not aligned properly on NetBSD
</td>
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<th>Product</th>
<td>clang
</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
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>mgorny@gentoo.org
</td>
</tr>
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>Demonstration program:
#include <cstdio>
struct alignas(64) a {
int x;
};
void b() {
thread_local a as_tls;
printf("as tls: %p\n", &as_tls);
}
int main() {
b();
return 0;
}
The result is:
as tls: 0x7f7ff7efe068
which is clearly not aligned properly. However, clang/llvm seems to assume the
alignment will take place and generates MOVAPS instructions that segfault due
to wrong alignment.
FWIU, this is a bug in NetBSD ld.so but it's not expected to be fixed anytime
soon. Is there any chance for a short-term solution that would e.g. add make
LLVM take more TLS space and round the returned address to obtain necessary
alignment?</pre>
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