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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - invalid instruction generated for atomic store of __int128 on aarch64"
href="https://llvm.org/bugs/show_bug.cgi?id=27081">27081</a>
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<th>Summary</th>
<td>invalid instruction generated for atomic store of __int128 on aarch64
</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>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: AArch64
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>yyc1992@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The following program generates an invalid instruction on llvm trunk.
```
#include <atomic>
#include <stdint.h>
std::atomic<__int128> a;
__attribute__((noinline)) void f(int64_t v)
{
a.store(v);
}
int main()
{
f(1);
return 0;
}
```
The assembly is
```
0000000000400610 <_Z1fl>:
400610: 90000089 adrp x9, 410000 <__FRAME_END__+0xf8a0>
400614: 937ffc08 asr x8, x0, #63
400618: 91278129 add x9, x9, #0x9e0
40061c: c87ffd3f ldaxp xzr, xzr, [x9]
400620: c82aa120 stlxp w10, x0, x8, [x9]
400624: 35ffffca cbnz w10, 40061c <_Z1fl+0xc>
400628: d65f03c0 ret
```
And the `ldaxp` instruction raise a SIGILL.
(GCC raises a linker error in this case...)</pre>
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