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

[Romain-Geissler-1A]

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

[llvmbot]

@llvm/issue-subscribers-tools-llvm-exegesis

[Romain-Geissler-1A]

I have submitted a patch here: https://reviews.llvm.org/D157189

[Romain-Geissler-1A]

/cherry-pick e82cc56

[Romain-Geissler-1A]

I have created #64497 to track the backport to branch 17.

[llvmbot]

/cherry-pick e82cc56

Error: Command failed due to missing milestone.