[PATCH 3/3] Add i386 memset and memcpy assembly functions

[H.J. Lu]

On Wed, Aug 26, 2015 at 7:29 AM, Ondřej Bílka <neleai@seznam.cz> wrote:
> On Wed, Aug 26, 2015 at 06:46:31AM -0700, H.J. Lu wrote:
>> Add i386 memset and memcpy assembly functions with REP MOVSB/STOSB
>> instructions.  They will be used to implement i386 multi-arch memcpy.
>>
>> OK for master?
>>
> No, as rep stosb has terrible performance on most of machines, on ivy
> bridge its around six times slower than rep stosq. I wouldn't be
>

I added them for i386 memcpy family multiarch functions.  We have
memcpy for i586 and i686:

sysdeps/i386/i586/memcpy.S
sysdeps/i386/i686/memcpy.S

But we don't have it for i486.  I add them so that I can implement
i386 memset and memcpy family multiarch functions for i486,
i586 and i686 targets.  i386 memset and memcpy are used only
when

1. Building glibc for i486 with --disable-multi-arch.  Or
2. Processor doesn't support i686 nor SSE2.

I believe these are a very rare cases.

-- 
H.J.