<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/131218>131218</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Arm CSSC not supported in target_version/target_clones
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

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

<pre>
    Compiling this file

```c
__attribute__((target_clones("cssc", "default")))
int foo(int x) {
    return __builtin_popcount(x);
}
```

with `clang --rtlib=compiler-rt` warns that

```
<source>:1:31: warning: unsupported 'cssc' in the 'target_clones' attribute string; 'target_clones' attribute ignored [-Wignored-attributes]
    1 | __attribute__((target_clones("cssc", "default")))
      | ^
<source>:1:31: warning: version list contains entries that don't impact code generation [-Wfunction-multiversion]
```

However, Clang does understand `-march=armv8.7-a+cssc`, so it knows about the extension.  Is there a different spelling for the `target_clones` attribute value?
</pre>
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