<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/146159>146159</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Modular Printf Implemenation
        </td>
    </tr>

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

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

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

<pre>
    This is a tracking issue for implemenation work for [RFC: printf Code Size Optimization](https://discourse.llvm.org/t/rfc-printf-code-size-optimization/83146).

This would take the form of a new clang function attribute, `modular_format(<modular_impl_fn>, <impl_name>, <aspects...>)`. This could only be applied to functions that also bear the `format` attribute. It would inform the compiler that it could redirect the call to the modular version of the function, so long as it emitted a reference to a symbol corresponding to each requested aspect that it could not prove is unused by the call.

The symbols referenced take the form `<impl_name>_<aspect>`, which allows many different front-end functions to share the same implementation. For example, `fprintf`, and `printf` would both share the implementation name `__printf`.

The initial implementation would support only the `float` aspect, which is required by any call with a floating point argument.
</pre>
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