mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-23 19:30:10 +00:00
c86f7b80f4
strnlen() is based on the existing tile strlen() with length checking added. It speeds up by up to 5x, but on average across the benchtest corpus by around 35%. No regressions are seen. strstr() does 8-byte aligned loads and compares using a 2-byte filter on the first two bytes of the needle and then testing the remaining bytes in needle using memcmp(). It speeds up about 5x in the best case (for "found" needles), about 2x looking at benchtest as a whole, with some slowdowns as much as 45%. on a few cases (including the "fail" case for 128KB search). strcasestr() is based on strstr() but uses a SIMD tolower routine to convert 8-bytes to lower case in 5 instructions. It also uses a 2-byte filter and then strncasecmp() for the remaining bytes. strncasecmp() is not optimized for SIMD, so there is futher room for improvement. However, it is still up to 16x faster for "found" needles, averaging 2x faster on the whole corpus of benchtests. It does slow down by up to 35% on a few cases, similarly to strstr().
59 lines
2.1 KiB
C
59 lines
2.1 KiB
C
/* Copyright (C) 2011-2014 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
|
|
|
|
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 <endian.h>
|
|
#include <stdint.h>
|
|
|
|
/* Provide a set of macros to help keep endianness #ifdefs out of
|
|
the string functions.
|
|
|
|
MASK: Provide a mask based on the pointer alignment that
|
|
sets up non-zero bytes before the beginning of the string.
|
|
The MASK expression works because shift counts are taken mod 64.
|
|
|
|
NULMASK: Clear bytes beyond a given point in the string.
|
|
|
|
CFZ: Find the first zero bit in the 8 string bytes in a long.
|
|
|
|
REVCZ: Find the last zero bit in the 8 string bytes in a long.
|
|
|
|
STRSHIFT: Shift N bits towards the start of the string. */
|
|
|
|
#if __BYTE_ORDER == __LITTLE_ENDIAN
|
|
#define MASK(x) (__insn_shl(1ULL, (x << 3)) - 1)
|
|
#define NULMASK(x) ((2ULL << x) - 1)
|
|
#define CFZ(x) __insn_ctz(x)
|
|
#define REVCZ(x) __insn_clz(x)
|
|
#define STRSHIFT(x,n) ((x) >> n)
|
|
#else
|
|
#define MASK(x) (__insn_shl(-2LL, ((-x << 3) - 1)))
|
|
#define NULMASK(x) (-2LL << (63 - x))
|
|
#define CFZ(x) __insn_clz(x)
|
|
#define REVCZ(x) __insn_ctz(x)
|
|
#define STRSHIFT(x,n) ((x) << n)
|
|
#endif
|
|
|
|
/* Create eight copies of the byte in a uint64_t. Byte Shuffle uses
|
|
the bytes of srcB as the index into the dest vector to select a
|
|
byte. With all indices of zero, the first byte is copied into all
|
|
the other bytes. */
|
|
static inline uint64_t copy_byte(uint8_t byte)
|
|
{
|
|
return __insn_shufflebytes(byte, 0, 0);
|
|
}
|