Hi Andrew,
On Thu, Jul 22, 2021 at 9:49 AM Andrew Rybchenko
<andrew.rybche...@oktetlabs.ru> wrote:
>
> Old clanng requires libatomic as well as gcc. Avoid compiler name and
s/nn/n/
> version based checks. Add custom test for 16-byte atomic operations
> to find out if libatomic is required to build.
>
> Bugzilla ID: 760
> Fixes: 96fd2bd69b58 ("net/sfc: support flow action count in transfer rules")
>
> Signed-off-by: Andrew Rybchenko <andrew.rybche...@oktetlabs.ru>
> ---
> drivers/net/sfc/meson.build | 22 +++++++++++++++-------
> 1 file changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/sfc/meson.build b/drivers/net/sfc/meson.build
> index 4625859077..a1ad792b80 100644
> --- a/drivers/net/sfc/meson.build
> +++ b/drivers/net/sfc/meson.build
> @@ -40,8 +40,20 @@ foreach flag: extra_flags
> endif
> endforeach
>
> -# for gcc compiles we need -latomic for 128-bit atomic ops
> -if cc.get_id() == 'gcc'
> +# for gcc and old Clang compiles we need -latomic for 128-bit atomic ops
> +atomic_check_code = '''
> +int main(void)
> +{
> + __int128 a = 0;
> + __int128 b;
> +
> + b = __atomic_load_n(&a, __ATOMIC_RELAXED);
> + __atomic_store(&b, &a, __ATOMIC_RELAXED);
> + __atomic_store_n(&b, a, __ATOMIC_RELAXED);
> + return 0;
> +}
> +'''
> +if not cc.links(atomic_check_code)
Nice.
> libatomic_dep = cc.find_library('atomic', required: false)
> if not libatomic_dep.found()
> build = false
> @@ -51,11 +63,7 @@ if cc.get_id() == 'gcc'
>
> # libatomic could be half-installed when above check finds it but
> # linkage fails
> - atomic_link_code = '''
> - #include <stdio.h>
> - void main() { printf("libatomic link check\n"); }
> - '''
> - if not cc.links(atomic_link_code, dependencies: libatomic_dep)
> + if not cc.links(atomic_check_code, dependencies: libatomic_dep)
> build = false
> reason = 'broken dependency, "libatomic"'
> subdir_done()
> --
> 2.30.2
>
Such a check will have its place in a common place if another
component in DPDK starts to depend on libatomic in the future.
But for now, this patch lgtm.
Thanks.
Acked-by: David Marchand <david.march...@redhat.com>
--
David Marchand
