libc: Remove the i386 assembler version of strlen(3).

On anything modern, the C version, which processes a word at a time, is much
faster. The Intel optimization manual explicitly warns against using REP
prefixes with SCAS or CMPS, which is exactly what the assembler version
does.

A simple test on a Phenom II showed the C version, compiled with -O2, to be
about twice as fast determining the length of 100000 strings between 0 and
255 bytes long.

MFC after:	2 weeks

2 files changed, 1 insertions, 55 deletions

diff --git a/lib/libc/i386/string/Makefile.inc b/lib/libc/i386/string/Makefile.inc
index cd908a6..3292267 100644
--- a/lib/libc/i386/string/Makefile.inc
+++ b/lib/libc/i386/string/Makefile.inc
@@ -3,5 +3,5 @@
 
 MDSRCS+=bcmp.S bcopy.S bzero.S ffs.S index.S memchr.S memcmp.S memcpy.S \
 	memmove.S memset.S rindex.S strcat.S strchr.S strcmp.S strcpy.S \
-	strlen.S strncmp.S strrchr.S swab.S wcschr.S wcscmp.S wcslen.S \
+	strncmp.S strrchr.S swab.S wcschr.S wcscmp.S wcslen.S \
 	wmemchr.S
diff --git a/lib/libc/i386/string/strlen.S b/lib/libc/i386/string/strlen.S
deleted file mode 100644
index 6e91f1a..0000000
--- a/lib/libc/i386/string/strlen.S
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- * Copyright (c) 1993 Winning Strategies, Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *      This product includes software developed by Winning Strategies, Inc.
- * 4. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-/*
- * strlen (s)
- *	compute the length of the string s.
- *
- * Written by:
- *	J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
- */
-
-ENTRY(strlen)
-	pushl	%edi
-	movl	8(%esp),%edi		/* string address */
-	cld				/* set search forward */
-	xorl	%eax,%eax		/* set search for null terminator */
-	movl	$-1,%ecx		/* set search for lots of characters */
-	repne				/* search! */
-	scasb
-	notl	%ecx			/* get length by taking complement */
-	leal	-1(%ecx),%eax		/* and subtracting one */
-	popl	%edi
-	ret
-END(strlen)