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Re: Proposal for CPU dispatching in libc
- From: Petr Baudis <pasky at suse dot cz>
- To: Agner Fog <agner at agner dot org>
- Cc: libc-help <libc-help at sourceware dot org>, lucaregini at yahoo dot it
- Date: Thu, 2 Jul 2009 10:51:36 +0200
- Subject: Re: Proposal for CPU dispatching in libc
- References: <1218049581.7809.60.camel@localhost> <489A8F1F.7050702@agner.org> <489ACA0D.2090705@agner.org> <119aab440808070431t1a935240i948a1206b720bfe@mail.gmail.com> <489AE2B2.9010703@agner.org> <119aab440808070533q1897acc9kb0223b09d64e1922@mail.gmail.com> <489BE528.7090807@agner.org> <119aab440808080522ne73089al9a0d36b3befe24bd@mail.gmail.com> <489D537F.3010005@agner.org> <4A4C6D86.8040705@agner.org>
Hi!
On Thu, Jul 02, 2009 at 10:19:18AM +0200, Agner Fog wrote:
> Last year I proposed to improve the string functions and various other
> functions in libc (see the thread "Why do you want libc to be 5 times
> slower than other libraries?", August 2008). However, due to lack of
> volunteers this was never implemented. Now Luca Regini has volunteered
> to help with this work so I am taking up the issue again. We are
> considering improving string and memory functions, and perhaps math
> functions, in libc for x86 and x86-64.
This work is already being done in glibc git tree by Ulrich Drepper
and H.J. Lu; a new ELF symbol type STT_GNU_IFUNC is used; if symbol
of this type is called, the function returns address of the actual
function that should be called on this and subsequent calls.
Currently, SSE4.2-optimized strcmp() is already committed.
--
Petr "Pasky" Baudis
The lyf so short, the craft so long to lerne. -- Chaucer