Date: Sun, 6 May 2007 07:50:25 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Bruce Evans <bde@zeta.org.au> Cc: Daniel Eischen <deischen@freebsd.org>, arch@freebsd.org, "Sean C. Farley" <sean-freebsd@farley.org> Subject: Re: HEADS DOWN Message-ID: <20070506045025.GB83173@deviant.kiev.zoral.com.ua> In-Reply-To: <20070506091835.A43775@besplex.bde.org> References: <Pine.GSO.4.64.0705022034180.8590@sea.ntplx.net> <20070502230413.Y30614@thor.farley.org> <20070503160351.GA15008@nagual.pp.ru> <20070504085905.J39482@thor.farley.org> <20070504213312.GA33163@nagual.pp.ru> <20070504174657.D1343@thor.farley.org> <20070505213202.GA49925@nagual.pp.ru> <20070505163707.J6670@thor.farley.org> <20070505221125.GA50439@nagual.pp.ru> <20070506091835.A43775@besplex.bde.org>
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--dc+cDN39EJAMEtIO Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Sun, May 06, 2007 at 10:59:23AM +1000, Bruce Evans wrote: > The setup overhead for using string instructions may be much larger than > the 14-16 in the above table. It is also necessary to set the direction > flag and maybe to shuffle registers so as to use the registers required > by the string instructions. cld/std is fast enough on Athlons (1/2 > cycles) but is slow on Pentium4 and later (IIRC, 43 cycles for std on > one Pentium model). gcc 4.3 claims to not issue cld instruction anymore (ABI requires direction flag to be clear since eon). --dc+cDN39EJAMEtIO Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (FreeBSD) iD8DBQFGPV6RC3+MBN1Mb4gRAgURAJ9mPDQQwgypxPRE3xJ7WibUSt4RBQCfVeKi uKtSbZEXEcjK7PvW8qGTP8c= =gE3J -----END PGP SIGNATURE----- --dc+cDN39EJAMEtIO--
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