<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/79474>79474</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [libc] need a better way to handle `PREFER_GENERIC`
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            libc
      </td>
    </tr>

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

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

<pre>
    We use `PREFER_GENERIC` to flag some targets such that we can test objects compiled without even `SSE2` support. However, due to the limitation of current cmake setup, this means that `-fno-sse2` will be added to the default builds to those objects, which is quite unfortunate. 

We need to have an approach to such as
```cmake
add_header_library(
  bitmask
 HDRS
    bitmask.h
  FLAGS
    PREFER_GENERIC=false
  DEPENDS
 libc.src.__support.common
    libc.src.__support.CPP.bit
 libc.src.__support.macros.properties.cpu_features
)
```
in which we can specify the default value of a flag.
</pre>
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