On Sat, Feb 01, 2020 at 03:02:02PM +0000, m...@netbsd.org 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