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/* Placeholder function, not used by any processor at the moment.
Copyright (C) 2022-2024 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/>. */
/* UNUSED. Exists purely as reference implementation. */
#include <isa-level.h>
#if ISA_SHOULD_BUILD (4)
# include <sysdep.h>
# ifdef USE_AS_WCSCHR
# define CHAR_REG esi
# define CHAR_SIZE 4
# define VPBROADCAST vpbroadcastd
# define VPCMP vpcmpd
# define VPCMPNE vpcmpneqd
# define VPMINU vpminud
# define VPTEST vptestmd
# define VPTESTN vptestnmd
# else
# define CHAR_REG sil
# define CHAR_SIZE 1
# define VPBROADCAST vpbroadcastb
# define VPCMP vpcmpb
# define VPCMPNE vpcmpneqb
# define VPMINU vpminub
# define VPTEST vptestmb
# define VPTESTN vptestnmb
# endif
# define PAGE_SIZE 4096
# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
# define VEC_MATCH_MASK ((1 << CHAR_PER_VEC) - 1)
.section SECTION(.text), "ax", @progbits
/* Aligning entry point to 64 byte, provides better performance for
one vector length string. */
ENTRY_P2ALIGN (STRCHR, 6)
/* Broadcast CHAR to VMM(0). */
VPBROADCAST %esi, %VMM(0)
movl %edi, %eax
sall $20,%eax
cmpl $((PAGE_SIZE - VEC_SIZE) << 20), %eax
ja L(page_cross)
VMOVU (%rdi), %VMM(1)
VPCMPNE %VMM(1), %VMM(0), %k1
VPTEST %VMM(1), %VMM(1), %k0{%k1}
KMOV %k0, %VRAX
/* Compare [w]char for null, mask bit will be set for match. */
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRAX
# else
inc %VRAX
# endif
jz L(align_more)
bsf %VRAX, %VRAX
# ifdef USE_AS_WCSCHR
leaq (%rdi, %rax, CHAR_SIZE), %rax
# else
add %rdi, %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
jne L(zero)
ret
L(zero):
xorl %eax, %eax
# endif
ret
L(ret_vec_x3):
subq $-VEC_SIZE, %rdi
L(ret_vec_x2):
subq $-VEC_SIZE, %rdi
L(ret_vec_x1):
bsf %VRAX, %VRAX
# ifdef USE_AS_WCSCHR
leaq (%rdi, %rax, CHAR_SIZE), %rax
# else
add %rdi, %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
jne L(zero)
# endif
ret
L(page_cross):
mov %rdi, %rax
movl %edi, %ecx
# ifdef USE_AS_WCSCHR
/* Calculate number of compare result bits to be skipped for
wide string alignment adjustment. */
andl $(VEC_SIZE - 1), %ecx
sarl $2, %ecx
# endif
/* ecx contains number of w[char] to be skipped as a result
of address alignment. */
andq $-VEC_SIZE, %rax
VMOVA (%rax), %VMM(1)
VPCMPNE %VMM(1), %VMM(0), %k1
VPTEST %VMM(1), %VMM(1), %k0{%k1}
KMOV %k0, %VRAX
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRAX
# else
inc %VRAX
# endif
/* Ignore number of character for alignment adjustment. */
shr %cl, %VRAX
jz L(align_more)
bsf %VRAX, %VRAX
# ifdef USE_AS_WCSCHR
leaq (%rdi, %rax, CHAR_SIZE), %rax
# else
addq %rdi, %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
jne L(zero)
# endif
ret
L(align_more):
/* Align rax to VEC_SIZE. */
andq $-VEC_SIZE, %rdi
/* Loop unroll 4 times for 4 vector loop. */
VMOVA VEC_SIZE(%rdi), %VMM(1)
VPCMPNE %VMM(1), %VMM(0), %k1
VPTEST %VMM(1), %VMM(1), %k0{%k1}
/* Increment rdi by vector size for further comparison and
return. */
subq $-VEC_SIZE, %rdi
KMOV %k0, %VRAX
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRAX
# else
inc %VRAX
# endif
jnz L(ret_vec_x1)
VMOVA VEC_SIZE(%rdi), %VMM(1)
VPCMPNE %VMM(1), %VMM(0), %k1
VPTEST %VMM(1), %VMM(1), %k0{%k1}
KMOV %k0, %VRAX
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRAX
# else
inc %VRAX
# endif
jnz L(ret_vec_x2)
VMOVA (VEC_SIZE * 2)(%rdi), %VMM(1)
VPCMPNE %VMM(1), %VMM(0), %k1
VPTEST %VMM(1), %VMM(1), %k0{%k1}
KMOV %k0, %VRAX
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRAX
# else
inc %VRAX
# endif
jnz L(ret_vec_x3)
VMOVA (VEC_SIZE * 3)(%rdi), %VMM(1)
VPCMPNE %VMM(1), %VMM(0), %k1
VPTEST %VMM(1), %VMM(1), %k0{%k1}
KMOV %k0, %VRDX
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRDX
# else
inc %VRDX
# endif
jnz L(ret_vec_x4)
/* Align address to VEC_SIZE * 4 for loop. */
andq $-(VEC_SIZE * 4), %rdi
L(loop):
/* VPMINU and VPCMP combination provide better performance as
compared to alternative combinations. */
VMOVA (VEC_SIZE * 4)(%rdi), %VMM(1)
VMOVA (VEC_SIZE * 5)(%rdi), %VMM(2)
VMOVA (VEC_SIZE * 6)(%rdi), %VMM(3)
VMOVA (VEC_SIZE * 7)(%rdi), %VMM(4)
VPCMPNE %VMM(1), %VMM(0), %k1
VPCMPNE %VMM(2), %VMM(0), %k2
VPMINU %VMM(2), %VMM(1), %VMM(2)
VPCMPNE %VMM(3), %VMM(0), %k3{%k1}
VPCMPNE %VMM(4), %VMM(0), %k4{%k2}
VPMINU %VMM(4), %VMM(3), %VMM(4)
VPMINU %VMM(2), %VMM(4), %VMM(4){%k3}{z}
VPTEST %VMM(4), %VMM(4), %k5{%k4}
KMOV %k5, %VRDX
subq $-(VEC_SIZE * 4), %rdi
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRDX
# else
inc %VRDX
# endif
jz L(loop)
VPTEST %VMM(1), %VMM(1), %k0{%k1}
KMOV %k0, %VRAX
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRAX
# else
inc %VRAX
# endif
jnz L(ret_vec_x1)
VPTEST %VMM(2), %VMM(2), %k0{%k2}
KMOV %k0, %VRAX
/* At this point, if k1 is non zero, null char must be in the
second vector. */
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRAX
# else
inc %VRAX
# endif
jnz L(ret_vec_x2)
VPTEST %VMM(3), %VMM(3), %k0{%k3}
KMOV %k0, %VRAX
# ifdef USE_AS_WCSCHR
sub $VEC_MATCH_MASK, %VRAX
# else
inc %VRAX
# endif
jnz L(ret_vec_x3)
/* At this point null [w]char must be in the fourth vector so no
need to check. */
L(ret_vec_x4):
bsf %VRDX, %VRDX
leaq (VEC_SIZE * 3)(%rdi, %rdx, CHAR_SIZE), %rax
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
jne L(zero_2)
# endif
ret
# ifndef USE_AS_STRCHRNUL
L(zero_2):
xor %eax, %eax
ret
# endif
END (STRCHR)
#endif
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