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/* Placeholder function, not used by any processor at the moment.
Copyright (C) 2022-2023 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_WCSRCHR
# define CHAR_SIZE 4
# define VPBROADCAST vpbroadcastd
# define VPCMPEQ vpcmpeqd
# define VPMINU vpminud
# define VPTESTN vptestnmd
# else
# define CHAR_SIZE 1
# define VPBROADCAST vpbroadcastb
# define VPCMPEQ vpcmpeqb
# define VPMINU vpminub
# define VPTESTN vptestnmb
# endif
# define PAGE_SIZE 4096
# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
.section SECTION(.text), "ax", @progbits
/* Aligning entry point to 64 byte, provides better performance for
one vector length string. */
ENTRY_P2ALIGN (STRRCHR, 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)
L(page_cross_continue):
/* Compare [w]char for null, mask bit will be set for match. */
VMOVU (%rdi), %VMM(1)
VPTESTN %VMM(1), %VMM(1), %k1
KMOV %k1, %VRCX
test %VRCX, %VRCX
jz L(align_more)
VPCMPEQ %VMM(1), %VMM(0), %k0
KMOV %k0, %VRAX
BLSMSK %VRCX, %VRCX
and %VRCX, %VRAX
jz L(ret)
BSR %VRAX, %VRAX
# ifdef USE_AS_WCSRCHR
leaq (%rdi, %rax, CHAR_SIZE), %rax
# else
add %rdi, %rax
# endif
L(ret):
ret
L(vector_x2_end):
VPCMPEQ %VMM(2), %VMM(0), %k2
KMOV %k2, %VRAX
BLSMSK %VRCX, %VRCX
and %VRCX, %VRAX
jz L(vector_x1_ret)
BSR %VRAX, %VRAX
leaq (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %rax
ret
/* Check the first vector at very last to look for match. */
L(vector_x1_ret):
VPCMPEQ %VMM(1), %VMM(0), %k2
KMOV %k2, %VRAX
test %VRAX, %VRAX
jz L(ret)
BSR %VRAX, %VRAX
# ifdef USE_AS_WCSRCHR
leaq (%rsi, %rax, CHAR_SIZE), %rax
# else
add %rsi, %rax
# endif
ret
L(align_more):
/* Zero r8 to store match result. */
xorl %r8d, %r8d
/* Save pointer of first vector, in case if no match found. */
movq %rdi, %rsi
/* Align pointer to vector size. */
andq $-VEC_SIZE, %rdi
/* Loop unroll for 2 vector loop. */
VMOVA (VEC_SIZE)(%rdi), %VMM(2)
VPTESTN %VMM(2), %VMM(2), %k0
KMOV %k0, %VRCX
test %VRCX, %VRCX
jnz L(vector_x2_end)
/* Save pointer of second vector, in case if no match
found. */
movq %rdi, %r9
/* Align address to VEC_SIZE * 2 for loop. */
andq $-(VEC_SIZE * 2), %rdi
.p2align 4,,11
L(loop):
/* 2 vector loop, as it provide better performance as compared
to 4 vector loop. */
VMOVA (VEC_SIZE * 2)(%rdi), %VMM(3)
VMOVA (VEC_SIZE * 3)(%rdi), %VMM(4)
VPCMPEQ %VMM(3), %VMM(0), %k1
VPCMPEQ %VMM(4), %VMM(0), %k2
VPMINU %VMM(3), %VMM(4), %VMM(5)
VPTESTN %VMM(5), %VMM(5), %k0
KOR %k1, %k2, %k3
subq $-(VEC_SIZE * 2), %rdi
/* If k0 and k3 zero, match and end of string not found. */
KORTEST %k0, %k3
jz L(loop)
/* If k0 is non zero, end of string found. */
KORTEST %k0, %k0
jnz L(endloop)
lea VEC_SIZE(%rdi), %r8
/* A match found, it need to be stored in r8 before loop
continue. */
/* Check second vector first. */
KMOV %k2, %VRDX
test %VRDX, %VRDX
jnz L(loop_vec_x2_match)
KMOV %k1, %VRDX
/* Match is in first vector, rdi offset need to be substracted
by VEC_SIZE. */
sub $VEC_SIZE, %r8
/* If second vector doesn't have match, first vector must
have match. */
L(loop_vec_x2_match):
BSR %VRDX, %VRDX
# ifdef USE_AS_WCSRCHR
sal $2, %rdx
# endif
add %rdx, %r8
jmp L(loop)
L(endloop):
/* Check if string end in first loop vector. */
VPTESTN %VMM(3), %VMM(3), %k0
KMOV %k0, %VRCX
test %VRCX, %VRCX
jnz L(loop_vector_x1_end)
/* Check if it has match in first loop vector. */
KMOV %k1, %VRAX
test %VRAX, %VRAX
jz L(loop_vector_x2_end)
BSR %VRAX, %VRAX
leaq (%rdi, %rax, CHAR_SIZE), %r8
/* String must end in second loop vector. */
L(loop_vector_x2_end):
VPTESTN %VMM(4), %VMM(4), %k0
KMOV %k0, %VRCX
KMOV %k2, %VRAX
BLSMSK %VRCX, %VRCX
/* Check if it has match in second loop vector. */
and %VRCX, %VRAX
jz L(check_last_match)
BSR %VRAX, %VRAX
leaq (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %rax
ret
/* String end in first loop vector. */
L(loop_vector_x1_end):
KMOV %k1, %VRAX
BLSMSK %VRCX, %VRCX
/* Check if it has match in second loop vector. */
and %VRCX, %VRAX
jz L(check_last_match)
BSR %VRAX, %VRAX
leaq (%rdi, %rax, CHAR_SIZE), %rax
ret
/* No match in first and second loop vector. */
L(check_last_match):
/* Check if any match recorded in r8. */
test %r8, %r8
jz L(vector_x2_ret)
movq %r8, %rax
ret
/* No match recorded in r8. Check the second saved vector
in begining. */
L(vector_x2_ret):
VPCMPEQ %VMM(2), %VMM(0), %k2
KMOV %k2, %VRAX
test %VRAX, %VRAX
jz L(vector_x1_ret)
/* Match found in the second saved vector. */
BSR %VRAX, %VRAX
leaq (VEC_SIZE)(%r9, %rax, CHAR_SIZE), %rax
ret
L(page_cross):
mov %rdi, %rax
movl %edi, %ecx
# ifdef USE_AS_WCSRCHR
/* 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)
VPTESTN %VMM(1), %VMM(1), %k1
KMOV %k1, %VRAX
SHR %cl, %VRAX
jz L(page_cross_continue)
VPCMPEQ %VMM(1), %VMM(0), %k0
KMOV %k0, %VRDX
SHR %cl, %VRDX
BLSMSK %VRAX, %VRAX
and %VRDX, %VRAX
jz L(ret)
BSR %VRAX, %VRAX
# ifdef USE_AS_WCSRCHR
leaq (%rdi, %rax, CHAR_SIZE), %rax
# else
add %rdi, %rax
# endif
ret
END (STRRCHR)
#endif
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