<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/118731>118731</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Optimize foldings of repeated sorted values, if the reducer is distributive
        </td>
    </tr>

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

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

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

<pre>
    I go into [further detail here](https://github.com/Rudxain/bin-rle.rs)

I'm aware this optimization may be considered "too niche", but I believe it makes more sense for a compiler to do this automatically than for a human to explicitly use this algorithm at runtime.

I'm also aware of the fact that it would be unlikely for an optimizer to infer that a dynamically-generated list has all of its values sorted **and** that the set of unique values is small relative to the list length.

However, it's much easier to apply this optimization if the list contents are statically-known. Yes, the optimizer might prefer to do constant-folding, but if the list is big enough it might be better to fold at runtime, where this optimization shines
</pre>
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