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Add a simple rawmemchr implementation. Use strlen for rawmemchr(s, '\0') as it

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is the fastest way to search for '\0'.  Otherwise use memchr with an infinite
size.  This is 3x faster on benchtests for large sizes.  Passes GLIBC tests.

	* sysdeps/aarch64/rawmemchr.S (__rawmemchr): New file.
	* sysdeps/aarch64/strlen.S (__strlen): Change to __strlen to avoid PLT.
This commit is contained in:
Wilco Dijkstra 2016-06-20 17:48:20 +01:00
parent b998e16e71
commit 58ec4fb881
3 changed files with 50 additions and 2 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2016-06-20 Wilco Dijkstra <wdijkstr@arm.com>
* sysdeps/aarch64/rawmemchr.S (__rawmemchr): New file.
* sysdeps/aarch64/strlen.S (__strlen): Change to __strlen to avoid PLT.
2016-06-20 Wilco Dijkstra <wdijkstr@arm.com>
* sysdeps/aarch64/memcpy.S (memcpy):

42
sysdeps/aarch64/rawmemchr.S Normal file
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@ -0,0 +1,42 @@
/* rawmemchr - find a character in a memory zone
Copyright (C) 2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
/* Special case rawmemchr (s, 0) as strlen, otherwise tailcall memchr.
Call strlen without setting up a full frame - it preserves x14/x15.
*/
ENTRY (__rawmemchr)
cbz w1, L(do_strlen)
mov x2, -1
b __memchr
L(do_strlen):
mov x15, x30
cfi_return_column (x15)
mov x14, x0
bl __strlen
add x0, x14, x0
ret x15
END (__rawmemchr)
weak_alias (__rawmemchr, rawmemchr)
libc_hidden_builtin_def (__rawmemchr)

5
sysdeps/aarch64/strlen.S
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@ -84,7 +84,7 @@
whether the first fetch, which may be misaligned, crosses a page
boundary. */
ENTRY_ALIGN (strlen, 6)
ENTRY_ALIGN (__strlen, 6)
and tmp1, srcin, MIN_PAGE_SIZE - 1
mov zeroones, REP8_01
cmp tmp1, MIN_PAGE_SIZE - 16
@ -213,5 +213,6 @@ L(page_cross):
csel data1, data1, tmp4, eq
csel data2, data2, tmp2, eq
b L(page_cross_entry)
END (strlen)
END (__strlen)
weak_alias (__strlen, strlen)
libc_hidden_builtin_def (strlen)