<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/136803>136803</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [RISCV] error: duplicated standard user-level extension 'zifencei' since LLVM 19
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            backend:RISC-V
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          wangpc-pp
      </td>
    </tr>
</table>

<pre>
    See: https://godbolt.org/z/cnan5zh41

Before LLVM 19, we can compile successfully with `-march=rv64gc_zifencei`. But since LLVM 19, it complains:
```
error: invalid arch name 'rv64gc_zifencei', duplicated standard user-level extension 'zifencei'
```

The behavior is not compatible.

Is there something I missed? I know there are issues with `zifencei` implication, did we decide to not accept standalone `zifencei`? But I don't see it in release notes...
</pre>
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