From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <dev-bounces@dpdk.org>
Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124])
	by inbox.dpdk.org (Postfix) with ESMTP id 0773845FFF;
	Mon,  6 Jan 2025 12:21:43 +0100 (CET)
Received: from mails.dpdk.org (localhost [127.0.0.1])
	by mails.dpdk.org (Postfix) with ESMTP id 7A28F40676;
	Mon,  6 Jan 2025 12:21:43 +0100 (CET)
Received: from dkmailrelay1.smartsharesystems.com
 (smartserver.smartsharesystems.com [77.243.40.215])
 by mails.dpdk.org (Postfix) with ESMTP id A36FE4014F
 for <dev@dpdk.org>; Mon,  6 Jan 2025 12:21:41 +0100 (CET)
Received: from smartserver.smartsharesystems.com
 (smartserver.smartsharesys.local [192.168.4.10])
 by dkmailrelay1.smartsharesystems.com (Postfix) with ESMTP id 587022027D;
 Mon,  6 Jan 2025 12:21:41 +0100 (CET)
Content-class: urn:content-classes:message
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Subject: RE: [PATCH v2 2/5] lib/eal: add portable version of
 __builtin_add_overflow
Date: Mon, 6 Jan 2025 12:21:39 +0100
X-MimeOLE: Produced By Microsoft Exchange V6.5
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35E9F995@smartserver.smartshare.dk>
In-Reply-To: <Z3u5Xw-tNSrKQ8O1@bricha3-mobl1.ger.corp.intel.com>
X-MS-Has-Attach: 
X-MS-TNEF-Correlator: 
Thread-Topic: [PATCH v2 2/5] lib/eal: add portable version of
 __builtin_add_overflow
Thread-Index: AdtgKz3ADP4+y7IZTpi+uj36uSzq8AAAPN5w
References: <1735857169-19131-1-git-send-email-andremue@linux.microsoft.com>
 <1735936781-24199-1-git-send-email-andremue@linux.microsoft.com>
 <1735936781-24199-3-git-send-email-andremue@linux.microsoft.com>
 <Z3u5Xw-tNSrKQ8O1@bricha3-mobl1.ger.corp.intel.com>
From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Bruce Richardson" <bruce.richardson@intel.com>,
 "Andre Muezerie" <andremue@linux.microsoft.com>
Cc: <dev@dpdk.org>
X-BeenThere: dev@dpdk.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <https://mails.dpdk.org/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://mails.dpdk.org/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <https://mails.dpdk.org/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org

> From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> Sent: Monday, 6 January 2025 12.07
>=20
> On Fri, Jan 03, 2025 at 12:39:38PM -0800, Andre Muezerie wrote:
> > __builtin_add_overflow is gcc specific. There's a need for a =
portable
> > version that can also be used with other compilers.
> >
> > This patch introduces rte_add_overflow.
> >
> > +/*
> > + * Function that allows performing simple arithmetic operations
> together with
> > + * checking whether the operation overflowed.
> > + * Example of usage:
> > + *     uint8_t overflow;
> > + *     uint16_t a, b, result;
> > + *     a =3D 1;
> > + *     b =3D 2;
> > + *     overflow =3D rte_add_overflow(a, b, &result);
> > + */
> > +#ifdef RTE_TOOLCHAIN_MSVC
> > +#define rte_add_overflow(a, b, res) _Generic((a), \
> > +	uint8_t : _addcarry_u8, \
> > +	uint16_t : _addcarry_u16, \
> > +	uint32_t : _addcarry_u32, \
> > +	uint64_t : _addcarry_u64)(0, a, b, res)
> > +#else
> > +#define rte_add_overflow(a, b, res) _Generic((a), \
> > +	uint8_t : __builtin_add_overflow, \
> > +	uint16_t : __builtin_add_overflow, \
> > +	uint32_t : __builtin_add_overflow, \
> > +	uint64_t : __builtin_add_overflow)(a, b, res)
> > +#endif
>=20
> For the gcc version, can you just simplify to the one-line below?
>=20
> #define rte_add_overflow __builtin_add_overflow

Yes, but then GCC compilation would not fail if "a" has some other type =
than the four types explicitly supported.
I prefer keeping the method used this v2 patch.