svn commit: r339011 - head/lib/libc/amd64/string

Mateusz Guzik mjg at FreeBSD.org
Sat Sep 29 07:40:53 UTC 2018


Author: mjg
Date: Sat Sep 29 07:40:52 2018
New Revision: 339011
URL: https://svnweb.freebsd.org/changeset/base/339011

Log:
  amd64: remove unnecessary cld from libc memcpy/bcopy
  
  The ABI specifies the direction forward on function call, making
  the cld instruction redundant.
  
  Approved by:	re (kib)

Modified:
  head/lib/libc/amd64/string/bcopy.S

Modified: head/lib/libc/amd64/string/bcopy.S
==============================================================================
--- head/lib/libc/amd64/string/bcopy.S	Sat Sep 29 06:54:52 2018	(r339010)
+++ head/lib/libc/amd64/string/bcopy.S	Sat Sep 29 07:40:52 2018	(r339011)
@@ -60,7 +60,6 @@ ENTRY(bcopy)
 	subq	%rsi,%r8
 	cmpq	%rcx,%r8	/* overlapping? */
 	jb	1f
-	cld			/* nope, copy forwards. */
 	shrq	$3,%rcx		/* copy by words */
 	rep
 	movsq


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