Re: CVS commit: src/common/lib/libc/arch

[Andrew Doran <ad%netbsd.org@localhost>]

On Sat, Feb 01, 2020 at 03:02:02PM +0000, maya%NetBSD.org@localhost wrote:
> On Mon, Jan 27, 2020 at 10:09:21PM +0000, Andrew Doran wrote:
> > Module Name:	src
> > Committed By:	ad
> > Date:		Mon Jan 27 22:09:21 UTC 2020
> > 
> > Removed Files:
> > 	src/common/lib/libc/arch/i386/string: memcmp.S
> > 	src/common/lib/libc/arch/x86_64/string: bcmp.S memcmp.S
> > 
> > Log Message:
> > x86 uses the C versions of bcmp() and memcmp() now.
> > 
> 
> Why?

REP CMPS is very slow on the modern CPUs I have access to.  The updated C
version is 1.5-10x faster in the configurations I have tried, from tiny
strings up to N-megabyte strings.  MOVS and STOS are very good though.

Andrew