glibc/sysdeps/x86_64/multiarch/strrchr-avx2.S
Noah Goldstein df7e295d18 x86: Optimize {str|wcs}rchr-avx2
The new code unrolls the main loop slightly without adding too much
overhead and minimizes the comparisons for the search CHAR.

Geometric Mean of all benchmarks New / Old: 0.832
See email for all results.

Full xcheck passes on x86_64 with and without multiarch enabled.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
2022-04-22 23:08:40 -05:00

349 lines
8.2 KiB
ArmAsm

/* strrchr/wcsrchr optimized with AVX2.
Copyright (C) 2017-2022 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
<https://www.gnu.org/licenses/>. */
#if IS_IN (libc)
# include <sysdep.h>
# ifndef STRRCHR
# define STRRCHR __strrchr_avx2
# endif
# ifdef USE_AS_WCSRCHR
# define VPBROADCAST vpbroadcastd
# define VPCMPEQ vpcmpeqd
# define VPMIN vpminud
# define CHAR_SIZE 4
# else
# define VPBROADCAST vpbroadcastb
# define VPCMPEQ vpcmpeqb
# define VPMIN vpminub
# define CHAR_SIZE 1
# endif
# ifndef VZEROUPPER
# define VZEROUPPER vzeroupper
# endif
# ifndef SECTION
# define SECTION(p) p##.avx
# endif
# define VEC_SIZE 32
# define PAGE_SIZE 4096
.section SECTION(.text), "ax", @progbits
ENTRY(STRRCHR)
movd %esi, %xmm7
movl %edi, %eax
/* Broadcast CHAR to YMM4. */
VPBROADCAST %xmm7, %ymm7
vpxor %xmm0, %xmm0, %xmm0
/* Shift here instead of `andl` to save code size (saves a fetch
block). */
sall $20, %eax
cmpl $((PAGE_SIZE - VEC_SIZE) << 20), %eax
ja L(cross_page)
L(page_cross_continue):
vmovdqu (%rdi), %ymm1
/* Check end of string match. */
VPCMPEQ %ymm1, %ymm0, %ymm6
vpmovmskb %ymm6, %ecx
testl %ecx, %ecx
jz L(aligned_more)
/* Only check match with search CHAR if needed. */
VPCMPEQ %ymm1, %ymm7, %ymm1
vpmovmskb %ymm1, %eax
/* Check if match before first zero. */
blsmskl %ecx, %ecx
andl %ecx, %eax
jz L(ret0)
bsrl %eax, %eax
addq %rdi, %rax
/* We are off by 3 for wcsrchr if search CHAR is non-zero. If
search CHAR is zero we are correct. Either way `andq
-CHAR_SIZE, %rax` gets the correct result. */
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
L(ret0):
L(return_vzeroupper):
ZERO_UPPER_VEC_REGISTERS_RETURN
/* Returns for first vec x1/x2 have hard coded backward search
path for earlier matches. */
.p2align 4,, 10
L(first_vec_x1):
VPCMPEQ %ymm2, %ymm7, %ymm6
vpmovmskb %ymm6, %eax
blsmskl %ecx, %ecx
andl %ecx, %eax
jnz L(first_vec_x1_return)
.p2align 4,, 4
L(first_vec_x0_test):
VPCMPEQ %ymm1, %ymm7, %ymm6
vpmovmskb %ymm6, %eax
testl %eax, %eax
jz L(ret1)
bsrl %eax, %eax
addq %r8, %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
L(ret1):
VZEROUPPER_RETURN
.p2align 4,, 10
L(first_vec_x0_x1_test):
VPCMPEQ %ymm2, %ymm7, %ymm6
vpmovmskb %ymm6, %eax
/* Check ymm2 for search CHAR match. If no match then check ymm1
before returning. */
testl %eax, %eax
jz L(first_vec_x0_test)
.p2align 4,, 4
L(first_vec_x1_return):
bsrl %eax, %eax
leaq 1(%rdi, %rax), %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
VZEROUPPER_RETURN
.p2align 4,, 10
L(first_vec_x2):
VPCMPEQ %ymm3, %ymm7, %ymm6
vpmovmskb %ymm6, %eax
blsmskl %ecx, %ecx
/* If no in-range search CHAR match in ymm3 then need to check
ymm1/ymm2 for an earlier match (we delay checking search
CHAR matches until needed). */
andl %ecx, %eax
jz L(first_vec_x0_x1_test)
bsrl %eax, %eax
leaq (VEC_SIZE + 1)(%rdi, %rax), %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
VZEROUPPER_RETURN
.p2align 4
L(aligned_more):
/* Save original pointer if match was in VEC 0. */
movq %rdi, %r8
/* Align src. */
orq $(VEC_SIZE - 1), %rdi
vmovdqu 1(%rdi), %ymm2
VPCMPEQ %ymm2, %ymm0, %ymm6
vpmovmskb %ymm6, %ecx
testl %ecx, %ecx
jnz L(first_vec_x1)
vmovdqu (VEC_SIZE + 1)(%rdi), %ymm3
VPCMPEQ %ymm3, %ymm0, %ymm6
vpmovmskb %ymm6, %ecx
testl %ecx, %ecx
jnz L(first_vec_x2)
/* Save pointer again before realigning. */
movq %rdi, %rsi
addq $(VEC_SIZE + 1), %rdi
andq $-(VEC_SIZE * 2), %rdi
.p2align 4
L(first_aligned_loop):
/* Do 2x VEC at a time. Any more and the cost of finding the
match outweights loop benefit. */
vmovdqa (VEC_SIZE * 0)(%rdi), %ymm4
vmovdqa (VEC_SIZE * 1)(%rdi), %ymm5
VPCMPEQ %ymm4, %ymm7, %ymm6
VPMIN %ymm4, %ymm5, %ymm8
VPCMPEQ %ymm5, %ymm7, %ymm10
vpor %ymm6, %ymm10, %ymm5
VPCMPEQ %ymm8, %ymm0, %ymm8
vpor %ymm5, %ymm8, %ymm9
vpmovmskb %ymm9, %eax
addq $(VEC_SIZE * 2), %rdi
/* No zero or search CHAR. */
testl %eax, %eax
jz L(first_aligned_loop)
/* If no zero CHAR then go to second loop (this allows us to
throw away all prior work). */
vpmovmskb %ymm8, %ecx
testl %ecx, %ecx
jz L(second_aligned_loop_prep)
/* Search char could be zero so we need to get the true match.
*/
vpmovmskb %ymm5, %eax
testl %eax, %eax
jnz L(first_aligned_loop_return)
.p2align 4,, 4
L(first_vec_x1_or_x2):
VPCMPEQ %ymm3, %ymm7, %ymm3
VPCMPEQ %ymm2, %ymm7, %ymm2
vpmovmskb %ymm3, %eax
vpmovmskb %ymm2, %edx
/* Use add for macro-fusion. */
addq %rax, %rdx
jz L(first_vec_x0_test)
/* NB: We could move this shift to before the branch and save a
bit of code size / performance on the fall through. The
branch leads to the null case which generally seems hotter
than char in first 3x VEC. */
salq $32, %rax
addq %rdx, %rax
bsrq %rax, %rax
leaq 1(%rsi, %rax), %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
VZEROUPPER_RETURN
.p2align 4,, 8
L(first_aligned_loop_return):
VPCMPEQ %ymm4, %ymm0, %ymm4
vpmovmskb %ymm4, %edx
salq $32, %rcx
orq %rdx, %rcx
vpmovmskb %ymm10, %eax
vpmovmskb %ymm6, %edx
salq $32, %rax
orq %rdx, %rax
blsmskq %rcx, %rcx
andq %rcx, %rax
jz L(first_vec_x1_or_x2)
bsrq %rax, %rax
leaq -(VEC_SIZE * 2)(%rdi, %rax), %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
VZEROUPPER_RETURN
/* Search char cannot be zero. */
.p2align 4
L(second_aligned_loop_set_furthest_match):
/* Save VEC and pointer from most recent match. */
L(second_aligned_loop_prep):
movq %rdi, %rsi
vmovdqu %ymm6, %ymm2
vmovdqu %ymm10, %ymm3
.p2align 4
L(second_aligned_loop):
/* Search 2x at at time. */
vmovdqa (VEC_SIZE * 0)(%rdi), %ymm4
vmovdqa (VEC_SIZE * 1)(%rdi), %ymm5
VPCMPEQ %ymm4, %ymm7, %ymm6
VPMIN %ymm4, %ymm5, %ymm1
VPCMPEQ %ymm5, %ymm7, %ymm10
vpor %ymm6, %ymm10, %ymm5
VPCMPEQ %ymm1, %ymm0, %ymm1
vpor %ymm5, %ymm1, %ymm9
vpmovmskb %ymm9, %eax
addq $(VEC_SIZE * 2), %rdi
testl %eax, %eax
jz L(second_aligned_loop)
vpmovmskb %ymm1, %ecx
testl %ecx, %ecx
jz L(second_aligned_loop_set_furthest_match)
vpmovmskb %ymm5, %eax
testl %eax, %eax
jnz L(return_new_match)
/* This is the hot patch. We know CHAR is inbounds and that
ymm3/ymm2 have latest match. */
.p2align 4,, 4
L(return_old_match):
vpmovmskb %ymm3, %eax
vpmovmskb %ymm2, %edx
salq $32, %rax
orq %rdx, %rax
bsrq %rax, %rax
/* Search char cannot be zero so safe to just use lea for
wcsrchr. */
leaq (VEC_SIZE * -2 -(CHAR_SIZE - 1))(%rsi, %rax), %rax
VZEROUPPER_RETURN
/* Last iteration also potentially has a match. */
.p2align 4,, 8
L(return_new_match):
VPCMPEQ %ymm4, %ymm0, %ymm4
vpmovmskb %ymm4, %edx
salq $32, %rcx
orq %rdx, %rcx
vpmovmskb %ymm10, %eax
vpmovmskb %ymm6, %edx
salq $32, %rax
orq %rdx, %rax
blsmskq %rcx, %rcx
andq %rcx, %rax
jz L(return_old_match)
bsrq %rax, %rax
/* Search char cannot be zero so safe to just use lea for
wcsrchr. */
leaq (VEC_SIZE * -2 -(CHAR_SIZE - 1))(%rdi, %rax), %rax
VZEROUPPER_RETURN
.p2align 4,, 4
L(cross_page):
movq %rdi, %rsi
andq $-VEC_SIZE, %rsi
vmovdqu (%rsi), %ymm1
VPCMPEQ %ymm1, %ymm0, %ymm6
vpmovmskb %ymm6, %ecx
/* Shift out zero CHAR matches that are before the begining of
src (rdi). */
shrxl %edi, %ecx, %ecx
testl %ecx, %ecx
jz L(page_cross_continue)
VPCMPEQ %ymm1, %ymm7, %ymm1
vpmovmskb %ymm1, %eax
/* Shift out search CHAR matches that are before the begining of
src (rdi). */
shrxl %edi, %eax, %eax
blsmskl %ecx, %ecx
/* Check if any search CHAR match in range. */
andl %ecx, %eax
jz L(ret2)
bsrl %eax, %eax
addq %rdi, %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
L(ret2):
VZEROUPPER_RETURN
END(STRRCHR)
#endif