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author | jilles <jilles@FreeBSD.org> | 2010-10-01 13:10:11 +0000 |
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committer | jilles <jilles@FreeBSD.org> | 2010-10-01 13:10:11 +0000 |
commit | d1afef8be57ed26602c57190abd66f744f580a4c (patch) | |
tree | f673f61b959f822e54ed050a00b32ad578882c75 /lib | |
parent | 35c65502b901091ef76d27653bcc588fa8117194 (diff) | |
download | FreeBSD-src-d1afef8be57ed26602c57190abd66f744f580a4c.zip FreeBSD-src-d1afef8be57ed26602c57190abd66f744f580a4c.tar.gz |
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
Diffstat (limited to 'lib')
-rw-r--r-- | lib/libc/i386/string/Makefile.inc | 2 | ||||
-rw-r--r-- | lib/libc/i386/string/strlen.S | 54 |
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) |