This is the mail archive of the
glibc-cvs@sourceware.org
mailing list for the glibc project.
GNU C Library master sources branch master updated. glibc-2.20-155-gbe9d4cc
- From: mshawcroft at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 5 Nov 2014 14:02:03 -0000
- Subject: GNU C Library master sources branch master updated. glibc-2.20-155-gbe9d4cc
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU C Library master sources".
The branch, master has been updated
via be9d4ccc7fe62751db1a5fdcb31958561dbbda9a (commit)
from 7110166d4fe36899c5ecf6fd31635f3cd75d8931 (commit)
Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.
- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=be9d4ccc7fe62751db1a5fdcb31958561dbbda9a
commit be9d4ccc7fe62751db1a5fdcb31958561dbbda9a
Author: Richard Earnshaw <rearnsha@arm.com>
Date: Wed Nov 5 13:51:56 2014 +0000
[AArch64] Add optimized strchrnul.
Here is an optimized implementation of __strchrnul. The
simplification that we don't have to track precisely why the loop
terminates (match or end-of-string) means we have to do less work in
both setup and the core inner loop. That means this should never be
slower than strchr.
As with strchr, the use of LD1 means we do not need different versions
for big-/little-endian.
diff --git a/ChangeLog b/ChangeLog
index 0929cb6..51469e1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2014-11-05 Richard Earnshaw <rearnsha@arm.com>
+
+ * sysdeps/aarch64/strchrnul.S: New file.
+
2014-11-05 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
* sysdeps/powerpc/powerpc64/power8/memset.S (MTVSRD_V1_R4): Simplify
diff --git a/NEWS b/NEWS
index 382d38d..4656531 100644
--- a/NEWS
+++ b/NEWS
@@ -32,6 +32,8 @@ Version 2.20
17084, 17086, 17088, 17092, 17097, 17125, 17135, 17137, 17150, 17153,
17187, 17213, 17259, 17261, 17262, 17263, 17319, 17325, 17354.
+* Optimized strchrnul implementation for AArch64. Contributed by ARM Ltd.
+
* Reverted change of ABI data structures for s390 and s390x:
On s390 and s390x the size of struct ucontext and jmp_buf was increased in
2.19. This change is reverted in 2.20. The introduced 2.19 symbol versions
diff --git a/sysdeps/aarch64/strchrnul.S b/sysdeps/aarch64/strchrnul.S
new file mode 100644
index 0000000..b98c2e9
--- /dev/null
+++ b/sysdeps/aarch64/strchrnul.S
@@ -0,0 +1,130 @@
+/* strchrnul - find a character or nul in a string
+
+ Copyright (C) 2014 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>
+
+/* Assumptions:
+ *
+ * ARMv8-a, AArch64
+ * Neon Available.
+ */
+
+/* Arguments and results. */
+#define srcin x0
+#define chrin w1
+
+#define result x0
+
+/* Locals and temporaries. */
+
+#define src x2
+#define tmp1 x3
+#define wtmp2 w4
+#define tmp3 x5
+
+#define vrepchr v0
+#define vdata1 v1
+#define vdata2 v2
+#define vhas_nul1 v3
+#define vhas_nul2 v4
+#define vhas_chr1 v5
+#define vhas_chr2 v6
+#define vrepmask v15
+#define vend1 v16
+
+/* Core algorithm.
+
+ For each 32-byte hunk we calculate a 64-bit syndrome value, with
+ two bits per byte (LSB is always in bits 0 and 1, for both big
+ and little-endian systems). For each tuple, bit 0 is set iff
+ the relevant byte matched the requested character or nul. Since the
+ bits in the syndrome reflect exactly the order in which things occur
+ in the original string a count_trailing_zeros() operation will
+ identify exactly which byte is causing the termination. */
+
+ENTRY (__strchrnul)
+ /* Magic constant 0x40100401 to allow us to identify which lane
+ matches the termination condition. */
+ mov wtmp2, #0x0401
+ movk wtmp2, #0x4010, lsl #16
+ dup vrepchr.16b, chrin
+ bic src, srcin, #31 /* Work with aligned 32-byte hunks. */
+ dup vrepmask.4s, wtmp2
+ ands tmp1, srcin, #31
+ b.eq L(loop)
+
+ /* Input string is not 32-byte aligned. Rather than forcing
+ the padding bytes to a safe value, we calculate the syndrome
+ for all the bytes, but then mask off those bits of the
+ syndrome that are related to the padding. */
+ ld1 {vdata1.16b, vdata2.16b}, [src], #32
+ neg tmp1, tmp1
+ cmeq vhas_nul1.16b, vdata1.16b, #0
+ cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b
+ cmeq vhas_nul2.16b, vdata2.16b, #0
+ cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b
+ orr vhas_chr1.16b, vhas_chr1.16b, vhas_nul1.16b
+ orr vhas_chr2.16b, vhas_chr2.16b, vhas_nul2.16b
+ and vhas_chr1.16b, vhas_chr1.16b, vrepmask.16b
+ and vhas_chr2.16b, vhas_chr2.16b, vrepmask.16b
+ lsl tmp1, tmp1, #1
+ addp vend1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128
+ mov tmp3, #~0
+ addp vend1.16b, vend1.16b, vend1.16b // 128->64
+ lsr tmp1, tmp3, tmp1
+
+ mov tmp3, vend1.2d[0]
+ bic tmp1, tmp3, tmp1 // Mask padding bits.
+ cbnz tmp1, L(tail)
+
+L(loop):
+ ld1 {vdata1.16b, vdata2.16b}, [src], #32
+ cmeq vhas_nul1.16b, vdata1.16b, #0
+ cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b
+ cmeq vhas_nul2.16b, vdata2.16b, #0
+ cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b
+ /* Use a fast check for the termination condition. */
+ orr vhas_chr1.16b, vhas_nul1.16b, vhas_chr1.16b
+ orr vhas_chr2.16b, vhas_nul2.16b, vhas_chr2.16b
+ orr vend1.16b, vhas_chr1.16b, vhas_chr2.16b
+ addp vend1.2d, vend1.2d, vend1.2d
+ mov tmp1, vend1.2d[0]
+ cbz tmp1, L(loop)
+
+ /* Termination condition found. Now need to establish exactly why
+ we terminated. */
+ and vhas_chr1.16b, vhas_chr1.16b, vrepmask.16b
+ and vhas_chr2.16b, vhas_chr2.16b, vrepmask.16b
+ addp vend1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128
+ addp vend1.16b, vend1.16b, vend1.16b // 128->64
+
+ mov tmp1, vend1.2d[0]
+L(tail):
+ /* Count the trailing zeros, by bit reversing... */
+ rbit tmp1, tmp1
+ /* Re-bias source. */
+ sub src, src, #32
+ clz tmp1, tmp1 /* ... and counting the leading zeros. */
+ /* tmp1 is twice the offset into the fragment. */
+ add result, src, tmp1, lsr #1
+ ret
+
+END(__strchrnul)
+weak_alias (__strchrnul, strchrnul)
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 4 +
NEWS | 2 +
sysdeps/aarch64/{strchr.S => strchrnul.S} | 94 +++++++++++++----------------
3 files changed, 49 insertions(+), 51 deletions(-)
copy sysdeps/aarch64/{strchr.S => strchrnul.S} (54%)
hooks/post-receive
--
GNU C Library master sources