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Re: K6 optimization && compiler builtins
- To: Ronald Wahl <Ronald dot Wahl at informatik dot tu-chemnitz dot de>
- Subject: Re: K6 optimization && compiler builtins
- From: Oleg Krivosheev <kriol at fnal dot gov>
- Date: Mon, 15 Dec 1997 20:52:03 -0600 (CST)
- cc: egcs at cygnus dot com
- Reply-To: egcs at cygnus dot com
hi,
On Mon, 15 Dec 1997, Ronald Wahl wrote:
> Date: Mon, 15 Dec 1997 23:36:17 +0100 (CET)
> From: Ronald Wahl <Ronald.Wahl@informatik.tu-chemnitz.de>
> Reply-To: egcs@cygnus.com
> To: egcs@cygnus.com
> Subject: K6 optimization && compiler builtins
>
> Hi,
>
> At the moment I'm playing with the string/memory routines of libc which
> are written in assembler. On a K6 (somtimes PPro also, Pentium not testet)
> I can get a performance gain of 10-40% (!). Now my question: If I use one
> of the string/memory functions (e.g. memcmp) in my programs, which one
> will be uses - the compiler builtin or the one in the libc?
i believe compiler built-in will be used if known
number of bytes to be copied. I checked once
what's going on while memcpy double.
Gcc substituted few inlined assembelr instructions
instead of function calls. It was on SPARC though...
Sorry, don't know about x86.
> If the builtin
> is used - is it possible to include my optimized versions (if ready)?
do you have patch against latest snapshot ?
OK