Proposal for CPU dispatching in libc

[Petr Baudis]

  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