On Wed, Dec 9, 2020 at 2:24 PM Seth Forshee seth.forshee@canonical.com wrote:
Building the BPF selftests with clang 11, I'm getting the following error:
CLNG-LLC [test_maps] profiler1.o In file included from progs/profiler1.c:6: progs/profiler.inc.h:260:17: error: use of unknown builtin '__builtin_preserve_enum_value' [-Wimplicit-function-declaration] int cgrp_id = bpf_core_enum_value(enum cgroup_subsys_id___local, ^ /home/ubuntu/unstable/tools/testing/selftests/bpf/tools/include/bpf/bpf_core_read.h:179:2: note: expanded from macro 'bpf_core_enum_value' __builtin_preserve_enum_value(*(typeof(enum_type) *)enum_value, BPF_ENUMVAL_VALUE) ^ 1 error generated. llc: error: llc: <stdin>:1:1: error: expected top-level entity BPF obj compilation failed
Addressed by fb3558127cb6 ("bpf: Fix selftest compilation on clang 11")
I see that test_core_reloc_enumval.c takes precautions around the use of __builtin_preserve_enum_value as it is currently only available in clang 12 nightlies. Is it possible to do something similar here? Though I see that the use of the builtin is not nearly so neatly localized as it is in test_core_reloc_enumval.c.
Thanks, Seth