Re: [COMMITTED] bpf: define __bpf__ as well as __BPF__ as a target macro

[Fangrui Song <maskray@google.com>]

On Mon, Aug 29, 2022 at 1:16 PM Jose E. Marchesi via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
>
> LLVM defines both __bpf__ and __BPF_ as target macros.
> GCC was defining only __BPF__.
>
> This patch defines __bpf__ as a target macro for BPF.
> Tested in bpf-unknown-none.
>
> gcc/ChangeLog:
>
>         * config/bpf/bpf.cc (bpf_target_macros): Define __bpf__ as a
>         target macro.
> ---
>  gcc/config/bpf/bpf.cc | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/gcc/config/bpf/bpf.cc b/gcc/config/bpf/bpf.cc
> index 7e37e080808..9cb56cfb287 100644
> --- a/gcc/config/bpf/bpf.cc
> +++ b/gcc/config/bpf/bpf.cc
> @@ -291,6 +291,7 @@ void
>  bpf_target_macros (cpp_reader *pfile)
>  {
>    builtin_define ("__BPF__");
> +  builtin_define ("__bpf__");
>
>    if (TARGET_BIG_ENDIAN)
>      builtin_define ("__BPF_BIG_ENDIAN__");
> --
> 2.30.2
>

Having multiple choices in this case seems to just add confusion to
users and making code search slightly more inconvenient.

How much code uses LLVM specific __bpf__? Can it be migrated? Should
LLVM undefine the macro instead?