lib/libc/amd64/string: add strchrnul implementations (scalar, baseline)
A lot better than the generic (pre) implementaion. We do not beat glibc
for long strings, likely due to glibc switching to AVX once the input is
sufficiently long. X86-64-v3 and v4 implementations may be added at a
future time.
os: FreeBSD
arch: amd64
cpu: 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
│ strchrnul_pre.out │ strchrnul_scalar.out │ strchrnul_baseline.out │
│ sec/op │ sec/op vs base │ sec/op vs base │
Short 129.68µ ± 3% 59.91µ ± 1% -53.80% (p=0.000 n=20) 44.37µ ± 1% -65.79% (p=0.000 n=20)
Mid 21.15µ ± 0% 19.30µ ± 0% -8.76% (p=0.000 n=20) 12.30µ ± 0% -41.85% (p=0.000 n=20)
Long 13.772µ ± 0% 11.028µ ± 0% -19.92% (p=0.000 n=20) 3.285µ ± 0% -76.15% (p=0.000 n=20)
geomean 33.55µ 23.36µ -30.37% 12.15µ -63.80%
│ strchrnul_pre.out │ strchrnul_scalar.out │ strchrnul_baseline.out │
│ B/s │ B/s vs base │ B/s vs base │
Short 919.3Mi ± 3% 1989.7Mi ± 1% +116.45% (p=0.000 n=20) 2686.8Mi ± 1% +192.28% (p=0.000 n=20)
Mid 5.505Gi ± 0% 6.033Gi ± 0% +9.60% (p=0.000 n=20) 9.466Gi ± 0% +71.97% (p=0.000 n=20)
Long 8.453Gi ± 0% 10.557Gi ± 0% +24.88% (p=0.000 n=20) 35.441Gi ± 0% +319.26% (p=0.000 n=20)
geomean 3.470Gi 4.983Gi +43.62% 9.584Gi +176.22%
For comparison, glibc on the same machine:
│ strchrnul_glibc.out │
│ sec/op │
Short 49.73µ ± 0%
Mid 14.60µ ± 0%
Long 1.237µ ± 0%
geomean 9.646µ
│ strchrnul_glibc.out │
│ B/s │
Short 2.341Gi ± 0%
Mid 7.976Gi ± 0%
Long 94.14Gi ± 0%
geomean 12.07Gi
Sponsored by: The FreeBSD Foundation
Approved by: mjg
Differential Revision: https://reviews.freebsd.org/D41333
This commit is contained in:
Robert Clausecker
parent
f1d955be2a
commit
61f4c4d3dd
@ -8,6 +8,7 @@ MDSRCS+= \
|
||||
memmove.S \
|
||||
memset.S \
|
||||
strcat.S \
|
||||
strchrnul.S \
|
||||
strcmp.S \
|
||||
strlen.S \
|
||||
stpcpy.S
|
||||
|
||||
167
lib/libc/amd64/string/strchrnul.S
Normal file
167
lib/libc/amd64/string/strchrnul.S
Normal file
@ -0,0 +1,167 @@
|
||||
/*-
|
||||
* Copyright (c) 2023 The FreeBSD Foundation
|
||||
*
|
||||
* This software was developed by Robert Clausecker <fuz@FreeBSD.org>
|
||||
* under sponsorship from the FreeBSD Foundation.
|
||||
*
|
||||
* 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.
|
||||
*
|
||||
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ''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 OR CONTRIBUTORS 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>
|
||||
|
||||
#include "amd64_archlevel.h"
|
||||
|
||||
#define ALIGN_TEXT .p2align 4,0x90 # 16-byte alignment, nop-filled
|
||||
|
||||
.weak strchrnul
|
||||
.set strchrnul, __strchrnul
|
||||
|
||||
ARCHFUNCS(__strchrnul)
|
||||
ARCHFUNC(__strchrnul, scalar)
|
||||
ARCHFUNC(__strchrnul, baseline)
|
||||
ENDARCHFUNCS(__strchrnul)
|
||||
|
||||
/*
|
||||
* strchrnul(str, c)
|
||||
* This is implemented like strlen(str), but we check for the
|
||||
* presence of both NUL and c in each iteration.
|
||||
*/
|
||||
ARCHENTRY(__strchrnul, scalar)
|
||||
mov %edi, %ecx
|
||||
and $~7, %rdi # align to 8 byte
|
||||
movzbl %sil, %esi # clear stray high bits
|
||||
movabs $0x0101010101010101, %r8
|
||||
mov (%rdi), %rax # load first word
|
||||
imul %r8, %rsi # replicate char 8 times
|
||||
movabs $0x8080808080808080, %r9
|
||||
|
||||
/*
|
||||
* Unaligned input: align to 8 bytes. Then proceed the same
|
||||
* way as with aligned input, but ignore matches before the
|
||||
* beginning of the string. This is achieved by shifting r9
|
||||
* into r10 to have 0x00 bytes before the string begins.
|
||||
*/
|
||||
shl $3, %ecx
|
||||
mov %r9, %r10
|
||||
add $8, %rdi
|
||||
shl %cl, %r10 # 0x80 where the string is
|
||||
neg %r8 # negate 01..01 so we can use lea
|
||||
|
||||
mov %rsi, %rcx
|
||||
xor %rax, %rcx # str ^ c
|
||||
lea (%rax, %r8, 1), %rdx # str - 0x01..01
|
||||
lea (%rcx, %r8, 1), %r11 # (str ^ c) - 0x01..01
|
||||
not %rax # ~str
|
||||
not %rcx # ~(str ^ c)
|
||||
and %rdx, %rax # (str - 0x01..01) & ~str
|
||||
and %r11, %rcx # ((str ^ c - 0x01..01) & ~(str ^ c)
|
||||
or %rcx, %rax # matches for both
|
||||
and %r10, %rax # not including junk bytes or bytes before the string
|
||||
jnz 1f
|
||||
|
||||
/* main loop unrolled twice */
|
||||
ALIGN_TEXT
|
||||
0: mov (%rdi), %rax # str
|
||||
mov %rsi, %rcx
|
||||
xor %rax, %rcx # str ^ c
|
||||
lea (%rax, %r8, 1), %rdx # str - 0x01..01
|
||||
lea (%rcx, %r8, 1), %r11 # (str ^ c) - 0x01..01
|
||||
not %rax # ~str
|
||||
not %rcx # ~(str ^ c)
|
||||
and %rdx, %rax # (str - 0x01..01) & ~str
|
||||
and %r11, %rcx # ((str ^ c - 0x01..01) & ~(str ^ c)
|
||||
or %rcx, %rax # matches for both
|
||||
and %r9, %rax # not including junk bits
|
||||
jnz 2f
|
||||
|
||||
mov 8(%rdi), %rax # str
|
||||
add $16, %rdi
|
||||
mov %rsi, %rcx
|
||||
xor %rax, %rcx # str ^ c
|
||||
lea (%rax, %r8, 1), %rdx # str - 0x01..01
|
||||
lea (%rcx, %r8, 1), %r11 # (str ^ c) - 0x01..01
|
||||
not %rax # ~str
|
||||
not %rcx # ~(str ^ c)
|
||||
and %rdx, %rax # (str - 0x01..01) & ~str
|
||||
and %r11, %rcx # ((str ^ c - 0x01..01) & ~(str ^ c)
|
||||
or %rcx, %rax # matches for both
|
||||
and %r9, %rax # not including junk bits
|
||||
jz 0b
|
||||
|
||||
/* NUL or c found */
|
||||
1: sub $8, %rdi # undo advance past buffer
|
||||
2: tzcnt %rax, %rax # first NUL or c byte match
|
||||
shr $3, %eax # scale from bit to byte index
|
||||
add %rdi, %rax # pointer to found c or NUL
|
||||
ret
|
||||
ARCHEND(__strchrnul, scalar)
|
||||
|
||||
ARCHENTRY(__strchrnul, baseline)
|
||||
mov %edi, %ecx
|
||||
and $~0xf, %rdi # align to 16 byte
|
||||
movdqa (%rdi), %xmm1
|
||||
movd %esi, %xmm0
|
||||
and $0xf, %ecx # distance from (%rdi) to start of string
|
||||
pxor %xmm2, %xmm2
|
||||
mov $-1, %edx
|
||||
punpcklbw %xmm0, %xmm0 # c -> cc
|
||||
shl %cl, %edx # bits corresponding to bytes in the string
|
||||
punpcklwd %xmm0, %xmm0 # cc -> cccc
|
||||
add $16, %rdi
|
||||
|
||||
/* check for match in head */
|
||||
pcmpeqb %xmm1, %xmm2 # NUL bytes present?
|
||||
pshufd $0, %xmm0, %xmm0 # cccc -> cccccccccccccccc
|
||||
pcmpeqb %xmm0, %xmm1 # c present?
|
||||
por %xmm2, %xmm1 # either present?
|
||||
pmovmskb %xmm1, %eax
|
||||
and %edx, %eax # match in the string?
|
||||
jnz 1f
|
||||
|
||||
/* main loop unrolled twice */
|
||||
ALIGN_TEXT
|
||||
0: movdqa (%rdi), %xmm1
|
||||
pxor %xmm2, %xmm2
|
||||
pcmpeqb %xmm1, %xmm2 # NUL bytes present?
|
||||
pcmpeqb %xmm0, %xmm1 # c present?
|
||||
por %xmm2, %xmm1 # either present?
|
||||
pmovmskb %xmm1, %eax
|
||||
test %eax, %eax # match in the string?
|
||||
jnz 2f
|
||||
|
||||
movdqa 16(%rdi), %xmm1
|
||||
add $32, %rdi
|
||||
pxor %xmm2, %xmm2
|
||||
pcmpeqb %xmm1, %xmm2 # NUL bytes present?
|
||||
pcmpeqb %xmm0, %xmm1 # c present?
|
||||
por %xmm2, %xmm1 # either present?
|
||||
pmovmskb %xmm1, %eax
|
||||
test %eax, %eax # match in the string?
|
||||
jz 0b
|
||||
|
||||
1: sub $16, %rdi # undo advance past buffer
|
||||
2: tzcnt %eax, %eax # where is the match?
|
||||
add %rdi, %rax # pointer to found c or NUL
|
||||
ret
|
||||
ARCHEND(__strchrnul, baseline)
|
||||
|
||||
.section .note.GNU-stack,"",%progbits
|
||||
Loading…
Reference in New Issue
Block a user