<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/98947>98947</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang doesn't accept LOCK prefix in assembler
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          VorfeedCanal
      </td>
    </tr>
</table>

<pre>
    As you can see all versions of GCC, even ancient ones accept `lock` as prefix: https://godbolt.org/z/q83EP7vc8

```
asm("LOCK CMPXCHGW %DI, 32768(%EDI,%EDI,8)");
```

Clang rejects it and if you put `LOCK` on separate line it comes before other prefixes while GCC puts it after.
</pre>
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