From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/3970 Path: news.gmane.org!not-for-mail From: Jens Gustedt Newsgroups: gmane.linux.lib.musl.general Subject: Re: Optimized C memset Date: Tue, 27 Aug 2013 10:52:55 +0200 Message-ID: <1377593575.25996.289.camel@eris.loria.fr> References: <20130827083020.GA4503@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-AQSrqQETnbQmDQlqfG74" X-Trace: ger.gmane.org 1377593589 32751 80.91.229.3 (27 Aug 2013 08:53:09 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 27 Aug 2013 08:53:09 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-3974-gllmg-musl=m.gmane.org@lists.openwall.com Tue Aug 27 10:53:11 2013 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1VEF1T-0007Q9-5a for gllmg-musl@plane.gmane.org; Tue, 27 Aug 2013 10:53:11 +0200 Original-Received: (qmail 30151 invoked by uid 550); 27 Aug 2013 08:53:07 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 30142 invoked from network); 27 Aug 2013 08:53:07 -0000 X-IronPort-AV: E=Sophos;i="4.89,966,1367964000"; d="scan'";a="30496500" In-Reply-To: <20130827083020.GA4503@brightrain.aerifal.cx> Face: 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Cj15cu23XZI4/826Px/xqB37z547sPH374oOvnKTsOb+1zuCoImZARM8ZiLlKkXcWOcoFRJ+Do/CwFO4e2DEe+9Ti+ZXA8ny/cU+X4bMKRZxZIVEiqXI6/+NKuUzPHb7z40ovnX3zx+Ctuq38HyuqWG7Tu+A0AAAAASUVORK5CYII= X-Mailer: Evolution 3.2.3-0ubuntu6 Xref: news.gmane.org gmane.linux.lib.musl.general:3970 Archived-At: --=-AQSrqQETnbQmDQlqfG74 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hello, Am Dienstag, den 27.08.2013, 04:30 -0400 schrieb Rich Felker: > One aspect of this code that may appear ugly at first is the usage of > the __GNUC__ macro. It not only *appears* to be ugly :) You already have a slight inconsistency in that at one point the code depends on a particular version of "gcc" and other part only depends on the fact that the __GNUC__ macro is set. There are a lot of compilers out there faking to be a gcc of some version and that are not always feature consistent with the gcc version that they are claming to fake. ICC is notorious for that. So to my opinion this is a dangerous path to follow. (I don't know about any problems with the __may_alias__ attribute, though) To make this easier to maintain, I'd suggest to introduce a special feature test macro, something like __has_may_alias__, and have that set at the beginning of the file in a section that is clearly dedicated to compile time feature detection. Other compilers may have different syntax for such a feature (a _Pragma comes in mind) and may be detected quite differently than by gcc version numbering. Such specific feature test macros is the way that clang goes, and from my experience this is much easier to maintain and to understand when you stumble on such #ifdef'ed code. You not only know that this needs a special version of a compiler, but also for what reason. Best Jens --=20 :: INRIA Nancy Grand Est :: http://www.loria.fr/~gustedt/ :: :: AlGorille ::::::::::::::: office Nancy : +33 383593090 :: :: ICube :::::::::::::: office Strasbourg : +33 368854536 :: :: ::::::::::::::::::::::::::: gsm France : +33 651400183 :: :: :::::::::::::::::::: gsm international : +49 15737185122 :: --=-AQSrqQETnbQmDQlqfG74 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEABECAAYFAlIcaOcACgkQD9PoadrVN+ISBACdFB8SeJldCxwrRvwDiydZEQmW yhMAn0W5XupcPyGospj1X5DlMuszC8ra =XHGE -----END PGP SIGNATURE----- --=-AQSrqQETnbQmDQlqfG74--