<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/83477>83477</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [apt.llvm.org] investigate thinLTO + PGO + BOLT builds of clang
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang,
            BOLT
      </td>
    </tr>

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

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

<pre>
    From a discussion https://github.com/ClangBuiltLinux/continuous-integration2/pull/719.

@nathanchance has some data about rebuilding clang with thinLTO + PGO + BOLT (with profiles from building linux kernels) significantly improves the build time relative to builds from apt.llvm.org.

ThinLTO isn't project specific, but "what project do you plan to build" has implications on the profile data used to feed PGO + BOLT.

For us, the scale of our CI bills justify having a purpose built compiler for building one project (which itself is perhaps interesting enough to be a talk/paper) when it's more than 50% faster.

We will continue to use apt.llvm.org, particularly the nightly builds.  But perhaps @nathanchance 's data and learnings can be integrated into the apt.llvm.org builds?
</pre>
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