<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/64456>64456</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            llvm-exegesis doesn't build when using gcc >= 10, glibc >= 2.35 but kernel headers < 4.18
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          Romain-Geissler-1A
      </td>
    </tr>
</table>

<pre>
    Hi,

The usage of `SYS_rseq` in `llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp` might not be ok when compiling with gcc >= 10, glibc >= 2.35 but rather old kernel headers (< 4.18). It's not common, but it happened to me:

```
[2023-08-05T02:06:18.024Z] /workdir/src/llvm-17.0.0/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp: In member function 'void llvm::exegesis::{anonymous}::SubProcessFunctionExecutorImpl::prepareAndRunBenchmark(int, const llvm::exegesis::BenchmarkKey&) const':
[2023-08-05T02:06:18.025Z] /workdir/src/llvm-17.0.0/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp:361:17: error: 'SYS_rseq' was not declared in this scope
[2023-08-05T02:06:18.025Z]   361 |         syscall(SYS_rseq, (intptr_t)__builtin_thread_pointer() + __rseq_offset,
[2023-08-05T02:06:18.025Z]       | ^~~~~~~~
```

I guess the preprocessor directive guarding this shall be modified to read:

```
-#ifdef GLIBC_INITS_RSEQ
+#if defined(GLIBC_INITS_RSEQ) && defined(SYS_rseq)
```

Cheers,
Romain
</pre>
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