From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrien Mazarguil Subject: Re: [PATCH v3] ppc64: fix compilation of when AltiVec is enabled Date: Mon, 3 Sep 2018 11:29:11 +0200 Message-ID: <20180903092911.GU3695@6wind.com> References: <20180830115959.28935-1-christian.ehrhardt@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: dev , Gowrishankar Muthukrishnan , Chao Zhu , Luca Boccassi , Thomas Monjalon To: Christian Ehrhardt Return-path: Received: from mail-wr1-f67.google.com (mail-wr1-f67.google.com [209.85.221.67]) by dpdk.org (Postfix) with ESMTP id 766C45B20 for ; Mon, 3 Sep 2018 11:29:28 +0200 (CEST) Received: by mail-wr1-f67.google.com with SMTP id v16-v6so17099129wro.11 for ; Mon, 03 Sep 2018 02:29:28 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20180830115959.28935-1-christian.ehrhardt@canonical.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi Christian, Couldn't follow up on this last week, however I still have some concerns and comments, please see below. On Thu, Aug 30, 2018 at 01:59:59PM +0200, Christian Ehrhardt wrote: > The definition of almost any newer standard like --stc=c11 will drop > __APPLCE_ALTIVEC__ which otherwise would be defined. > If that is the case then altivec.h will redefine bool to a type > conflicting with those defined by stdbool.h. > > This breaks compilation of 18.08 on ppc64 like: > mlx5_nl_flow.c:407:17: error: incompatible types when assigning > to type ‘__vector __bool int’ {aka ‘__vector(4) __bool int’} > from type ‘int’ in_port_id_set = false; > > Other alternatives were pursued on [1] but they always ended up being > more complex than what would be appropriate for the issue we face. > > [1]: http://mails.dpdk.org/archives/dev/2018-August/109926.html > > Tested-by: Takeshi T Yoshimura > Reviewed-by: Adrien Mazarguil > Signed-off-by: Christian Ehrhardt > --- > .../common/include/arch/ppc_64/rte_memcpy.h | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/lib/librte_eal/common/include/arch/ppc_64/rte_memcpy.h b/lib/librte_eal/common/include/arch/ppc_64/rte_memcpy.h > index 75f74897b..0b3b89b56 100644 > --- a/lib/librte_eal/common/include/arch/ppc_64/rte_memcpy.h > +++ b/lib/librte_eal/common/include/arch/ppc_64/rte_memcpy.h > @@ -37,6 +37,17 @@ > #include > /*To include altivec.h, GCC version must >= 4.8 */ > #include > +/* > + * Compilation workaround for PPC64 targets when AltiVec is fully > + * enabled e.g. with std=c11. Otherwise there would be a type conflict > + * of "bool" between stdbool and altivec. > + */ > +#if defined(__PPC64__) && !defined(__APPLE_ALTIVEC__) > + #undef bool > + /* redefine as in stdbool.h */ > + #define bool _Bool > +#endif > + The above will break existing C++ programs that include rte_memcpy.h. Problem is that bool is an actual C++ type. C99 has _Bool which doesn't exist in C++ along with a bool macro that appears only after including stdbool.h. To make things worse, nothing prevents C++ programs from importing a C-style bool macro by including stdbool.h (or cstdbool). Enclosing it in #ifdef __cplusplus won't help because you never know what bool is supposed to be in the first place as it depends on how applications are written. I think something like this prior suggestion [1] (saving/restoring bool) is the only way to deal with that in a safe-ish fashion. Pending something better, the above #undef/#define workaround is only safe to use inside mlx5 PMD code that triggers the compilation issue. It must not be found in a public header. > #ifdef __cplusplus > extern "C" { > -- > 2.17.1 > [1] https://mails.dpdk.org/archives/dev/2018-August/110401.html -- Adrien Mazarguil 6WIND