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Re: [PATCH 2/2] Improve 64bit memcpy/memmove for Corei7 with avx2 instruction
- From: Nix <nix at esperi dot org dot uk>
- To: OndÅej BÃlka <neleai at seznam dot cz>
- Cc: Ling Ma <ling dot ma dot program at gmail dot com>, libc-alpha at sourceware dot org, hongjiu dot lu at intel dot com
- Date: Fri, 07 Jun 2013 13:18:19 +0100
- Subject: Re: [PATCH 2/2] Improve 64bit memcpy/memmove for Corei7 with avx2 instruction
- References: <1370424188-4259-1-git-send-email-ling dot ml at alibaba-inc dot com> <20130605121816 dot GA11269 at domone dot kolej dot mff dot cuni dot cz> <CAOGi=dMiD=_Qf1EJ=F3hfyQDtQubDEC5pjpXKDCHrUQwhr=vzg at mail dot gmail dot com> <20130605161954 dot GA26401 at domone dot kolej dot mff dot cuni dot cz> <CAOGi=dPWPaX5prcL-uAaqS6=_ehzKeBmAFMdwV6aU34jZ0eHtQ at mail dot gmail dot com> <20130606125511 dot GA28565 at domone dot kolej dot mff dot cuni dot cz> <CAOGi=dPs9geCtrWhU1L_0DEfOWOknpzFSLmYs4gbYzGX8Zn5Hg at mail dot gmail dot com> <20130607104613 dot GA6343 at domone dot kolej dot mff dot cuni dot cz>
On 7 Jun 2013, OndÅej BÃlka said:
> On Thu, Jun 06, 2013 at 08:11:15PM +0800, Ling Ma wrote:
> I got some afterthoughts how improve memcpy/memset.
>
> First is to copy in backward direction.
Don't we already do this in some situations? That's why there's a new
symbol version of memcpy() et al on glibc 2.14+, because overlapping
memcpy() no longer works and lots and lots of programs were relying on
this (even though it was never ever guaranteed) and were breaking.
--
NULL && (void)