From: Andreas Jaeger <aj@suse.de>
To: GNU libc hacker <libc-hacker@sources.redhat.com>
Subject: i386/strchr.S broken?
Date: Sat, 10 Aug 2002 09:54:00 -0000 [thread overview]
Message-ID: <u8vg6ihcyc.fsf@gromit.moeb> (raw)
Looking at the i386/strchr.S file I noticed:
L(7): testb %cl, %cl /* is first byte C? */
jz L(6) /* yes => return pointer */
cmpb %dl, %cl /* is first byte NUL? */
je L(2) /* yes => return NULL */
incl %eax /* it's not in the first byte */
This looks broken to me, IMO it should be:
L(7): testb %cl, %cl /* is first byte NUL? */
jz L(2) /* yes => return NULL */
cmpb %dl, %cl /* is first byte C? */
je L(6) /* yes => return pointer */
incl %eax /* it's not in the first byte */
I'm appending an (untested) patch. Ok to commit for both branches?
The i586 version looks fine,
Andreas
2002-08-10 Andreas Jaeger <aj@suse.de>
* sysdeps/i386/strchr.S: Correct implementation.
============================================================
Index: sysdeps/i386/strchr.S
--- sysdeps/i386/strchr.S 6 Jul 2001 04:55:52 -0000 1.11
+++ sysdeps/i386/strchr.S 10 Aug 2002 16:52:38 -0000
@@ -1,6 +1,6 @@
/* strchr (str, ch) -- Return pointer to first occurrence of CH in STR.
For Intel 80x86, x>=3.
- Copyright (C) 1994, 1995, 1996, 1997, 1999, 2000 Free Software Foundation, Inc.
+ Copyright (C) 1994, 1995, 1996, 1997, 1999, 2000, 2002 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>
Some optimisations by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au>
@@ -256,23 +256,23 @@ L(71): addl $4, %eax
But we have to take care of the case that a NUL char is
found before this in the dword. */
-L(7): testb %cl, %cl /* is first byte C? */
- jz L(6) /* yes => return pointer */
- cmpb %dl, %cl /* is first byte NUL? */
+L(7): testb %cl, %cl /* is first byte NUL? */
je L(2) /* yes => return NULL */
+ cmpb %dl, %cl /* is first byte C? */
+ jz L(6) /* yes => return pointer */
incl %eax /* it's not in the first byte */
- testb %ch, %ch /* is second byte C? */
- jz L(6) /* yes => return pointer */
- cmpb %dl, %ch /* is second byte NUL? */
+ testb %ch, %ch /* is second byte NUL? */
je L(2) /* yes => return NULL? */
+ cmpb %dl, %ch /* is second byte C? */
+ jz L(6) /* yes => return pointer */
incl %eax /* it's not in the second byte */
shrl $16, %ecx /* make upper byte accessible */
- testb %cl, %cl /* is third byte C? */
- jz L(6) /* yes => return pointer */
- cmpb %dl, %cl /* is third byte NUL? */
+ testb %cl, %cl /* is third byte NUL? */
je L(2) /* yes => return NULL */
+ cmpb %dl, %cl /* is third byte C? */
+ jz L(6) /* yes => return pointer */
/* It must be in the fourth byte and it cannot be NUL. */
incl %eax
--
Andreas Jaeger
SuSE Labs aj@suse.de
private aj@arthur.inka.de
http://www.suse.de/~aj
next reply other threads:[~2002-08-10 16:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-10 9:54 Andreas Jaeger [this message]
2002-08-10 10:02 ` Andreas Jaeger
2002-08-10 11:01 ` Ulrich Drepper
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