Re: [PATCH bpf-next v2 8/9] selftests/bpf: Add selftests for load-acquire and store-release instructions

[Peilin Ye <yepeilin@google.com>]

On Tue, Feb 11, 2025 at 08:51:07PM +0000, Peilin Ye wrote:
> > > > Nit: why is dummy_test() necessary?
> > > 
> > > It's just to make it clear when these tests are (effectively) skipped.

<...>

> > > Commit 147c8f4470ee ("selftests/bpf: Add unit tests for new
> > > sign-extension load insns") did similar thing in verifier_ldsx.c.
> > 
> > I see, thank you for explaining.
> > We do have a concept of skipped tests in the test-suite,
> > but it is implemented by calling test__skip() from the prog_tests/<smth>.c.
> > This would translate as something like below in prog_tests/verifier.c:
> > 
> > 	void test_verifier_store_release(void) {
> > 	#if defined(ENABLE_ATOMICS_TESTS) && defined(__TARGET_ARCH_arm64)
> > 		RUN(verifier_store_release);
> > 	#else
> > 		test__skip()
> > 	#endif
> > 	}
> 
> > The number of tests skipped is printed after tests execution.

I tried:

  void test_verifier_load_acquire(void)
  {
  #if __clang_major__ >= 18 && defined(ENABLE_ATOMICS_TESTS) && defined(__aarch64__)
          RUN(verifier_load_acquire);
  #else
          printf("%s:SKIP: Clang version < 18, ENABLE_ATOMICS_TESTS not defined, and/or JIT doesn't support load-acquire\n",
                 __func__);
          test__skip();
  #endif
  }

Then realized that I can't check __clang_major__ in .../prog_tests/*
files (e.g. I was building prog_tests/verifier.c using GCC).  I think
ideally we should do something similar to prog{,_test}s/arena_atomics.c,
i.e. use a global bool in BPF source to indicate if we should skip this
test, but that seems to require non-trivial changes to
prog_tests/verifier.c?

For the purpose of this patchset, let me keep dummy_test(), like what we
have now in verifier_ldsx.c.

Thanks,
Peilin Ye