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/* strchr/strchrnul optimized with 256-bit EVEX instructions.
Copyright (C) 2021 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 STRCHR
# define STRCHR __strchr_evex
# endif
# define VMOVU vmovdqu64
# define VMOVA vmovdqa64
# ifdef USE_AS_WCSCHR
# define VPBROADCAST vpbroadcastd
# define VPCMP vpcmpd
# define VPMINU vpminud
# define CHAR_REG esi
# define SHIFT_REG r8d
# else
# define VPBROADCAST vpbroadcastb
# define VPCMP vpcmpb
# define VPMINU vpminub
# define CHAR_REG sil
# define SHIFT_REG ecx
# endif
# define XMMZERO xmm16
# define YMMZERO ymm16
# define YMM0 ymm17
# define YMM1 ymm18
# define YMM2 ymm19
# define YMM3 ymm20
# define YMM4 ymm21
# define YMM5 ymm22
# define YMM6 ymm23
# define YMM7 ymm24
# define YMM8 ymm25
# define VEC_SIZE 32
# define PAGE_SIZE 4096
.section .text.evex,"ax",@progbits
ENTRY (STRCHR)
movl %edi, %ecx
# ifndef USE_AS_STRCHRNUL
xorl %edx, %edx
# endif
/* Broadcast CHAR to YMM0. */
VPBROADCAST %esi, %YMM0
vpxorq %XMMZERO, %XMMZERO, %XMMZERO
/* Check if we cross page boundary with one vector load. */
andl $(PAGE_SIZE - 1), %ecx
cmpl $(PAGE_SIZE - VEC_SIZE), %ecx
ja L(cross_page_boundary)
/* Check the first VEC_SIZE bytes. Search for both CHAR and the
null bytes. */
VMOVU (%rdi), %YMM1
/* Leaves only CHARS matching esi as 0. */
vpxorq %YMM1, %YMM0, %YMM2
VPMINU %YMM2, %YMM1, %YMM2
/* Each bit in K0 represents a CHAR or a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM2, %k0
ktestd %k0, %k0
jz L(more_vecs)
kmovd %k0, %eax
tzcntl %eax, %eax
/* Found CHAR or the null byte. */
# ifdef USE_AS_WCSCHR
/* NB: Multiply wchar_t count by 4 to get the number of bytes. */
leaq (%rdi, %rax, 4), %rax
# else
addq %rdi, %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
cmovne %rdx, %rax
# endif
ret
.p2align 4
L(more_vecs):
/* Align data for aligned loads in the loop. */
andq $-VEC_SIZE, %rdi
L(aligned_more):
/* Check the next 4 * VEC_SIZE. Only one VEC_SIZE at a time
since data is only aligned to VEC_SIZE. */
VMOVA VEC_SIZE(%rdi), %YMM1
addq $VEC_SIZE, %rdi
/* Leaves only CHARS matching esi as 0. */
vpxorq %YMM1, %YMM0, %YMM2
VPMINU %YMM2, %YMM1, %YMM2
/* Each bit in K0 represents a CHAR or a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM2, %k0
kmovd %k0, %eax
testl %eax, %eax
jnz L(first_vec_x0)
VMOVA VEC_SIZE(%rdi), %YMM1
/* Leaves only CHARS matching esi as 0. */
vpxorq %YMM1, %YMM0, %YMM2
VPMINU %YMM2, %YMM1, %YMM2
/* Each bit in K0 represents a CHAR or a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM2, %k0
kmovd %k0, %eax
testl %eax, %eax
jnz L(first_vec_x1)
VMOVA (VEC_SIZE * 2)(%rdi), %YMM1
/* Leaves only CHARS matching esi as 0. */
vpxorq %YMM1, %YMM0, %YMM2
VPMINU %YMM2, %YMM1, %YMM2
/* Each bit in K0 represents a CHAR or a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM2, %k0
kmovd %k0, %eax
testl %eax, %eax
jnz L(first_vec_x2)
VMOVA (VEC_SIZE * 3)(%rdi), %YMM1
/* Leaves only CHARS matching esi as 0. */
vpxorq %YMM1, %YMM0, %YMM2
VPMINU %YMM2, %YMM1, %YMM2
/* Each bit in K0 represents a CHAR or a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM2, %k0
ktestd %k0, %k0
jz L(prep_loop_4x)
kmovd %k0, %eax
tzcntl %eax, %eax
/* Found CHAR or the null byte. */
# ifdef USE_AS_WCSCHR
/* NB: Multiply wchar_t count by 4 to get the number of bytes. */
leaq (VEC_SIZE * 3)(%rdi, %rax, 4), %rax
# else
leaq (VEC_SIZE * 3)(%rdi, %rax), %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
cmovne %rdx, %rax
# endif
ret
.p2align 4
L(first_vec_x0):
tzcntl %eax, %eax
/* Found CHAR or the null byte. */
# ifdef USE_AS_WCSCHR
/* NB: Multiply wchar_t count by 4 to get the number of bytes. */
leaq (%rdi, %rax, 4), %rax
# else
addq %rdi, %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
cmovne %rdx, %rax
# endif
ret
.p2align 4
L(first_vec_x1):
tzcntl %eax, %eax
/* Found CHAR or the null byte. */
# ifdef USE_AS_WCSCHR
/* NB: Multiply wchar_t count by 4 to get the number of bytes. */
leaq VEC_SIZE(%rdi, %rax, 4), %rax
# else
leaq VEC_SIZE(%rdi, %rax), %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
cmovne %rdx, %rax
# endif
ret
.p2align 4
L(first_vec_x2):
tzcntl %eax, %eax
/* Found CHAR or the null byte. */
# ifdef USE_AS_WCSCHR
/* NB: Multiply wchar_t count by 4 to get the number of bytes. */
leaq (VEC_SIZE * 2)(%rdi, %rax, 4), %rax
# else
leaq (VEC_SIZE * 2)(%rdi, %rax), %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
cmovne %rdx, %rax
# endif
ret
L(prep_loop_4x):
/* Align data to 4 * VEC_SIZE. */
andq $-(VEC_SIZE * 4), %rdi
.p2align 4
L(loop_4x_vec):
/* Compare 4 * VEC at a time forward. */
VMOVA (VEC_SIZE * 4)(%rdi), %YMM1
VMOVA (VEC_SIZE * 5)(%rdi), %YMM2
VMOVA (VEC_SIZE * 6)(%rdi), %YMM3
VMOVA (VEC_SIZE * 7)(%rdi), %YMM4
/* Leaves only CHARS matching esi as 0. */
vpxorq %YMM1, %YMM0, %YMM5
vpxorq %YMM2, %YMM0, %YMM6
vpxorq %YMM3, %YMM0, %YMM7
vpxorq %YMM4, %YMM0, %YMM8
VPMINU %YMM5, %YMM1, %YMM5
VPMINU %YMM6, %YMM2, %YMM6
VPMINU %YMM7, %YMM3, %YMM7
VPMINU %YMM8, %YMM4, %YMM8
VPMINU %YMM5, %YMM6, %YMM1
VPMINU %YMM7, %YMM8, %YMM2
VPMINU %YMM1, %YMM2, %YMM1
/* Each bit in K0 represents a CHAR or a null byte. */
VPCMP $0, %YMMZERO, %YMM1, %k0
addq $(VEC_SIZE * 4), %rdi
ktestd %k0, %k0
jz L(loop_4x_vec)
/* Each bit in K0 represents a CHAR or a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM5, %k0
kmovd %k0, %eax
testl %eax, %eax
jnz L(first_vec_x0)
/* Each bit in K1 represents a CHAR or a null byte in YMM2. */
VPCMP $0, %YMMZERO, %YMM6, %k1
kmovd %k1, %eax
testl %eax, %eax
jnz L(first_vec_x1)
/* Each bit in K2 represents a CHAR or a null byte in YMM3. */
VPCMP $0, %YMMZERO, %YMM7, %k2
/* Each bit in K3 represents a CHAR or a null byte in YMM4. */
VPCMP $0, %YMMZERO, %YMM8, %k3
# ifdef USE_AS_WCSCHR
/* NB: Each bit in K2/K3 represents 4-byte element. */
kshiftlw $8, %k3, %k1
# else
kshiftlq $32, %k3, %k1
# endif
/* Each bit in K1 represents a NULL or a mismatch. */
korq %k1, %k2, %k1
kmovq %k1, %rax
tzcntq %rax, %rax
# ifdef USE_AS_WCSCHR
/* NB: Multiply wchar_t count by 4 to get the number of bytes. */
leaq (VEC_SIZE * 2)(%rdi, %rax, 4), %rax
# else
leaq (VEC_SIZE * 2)(%rdi, %rax), %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
cmovne %rdx, %rax
# endif
ret
/* Cold case for crossing page with first load. */
.p2align 4
L(cross_page_boundary):
andq $-VEC_SIZE, %rdi
andl $(VEC_SIZE - 1), %ecx
VMOVA (%rdi), %YMM1
/* Leaves only CHARS matching esi as 0. */
vpxorq %YMM1, %YMM0, %YMM2
VPMINU %YMM2, %YMM1, %YMM2
/* Each bit in K0 represents a CHAR or a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM2, %k0
kmovd %k0, %eax
testl %eax, %eax
# ifdef USE_AS_WCSCHR
/* NB: Divide shift count by 4 since each bit in K1 represent 4
bytes. */
movl %ecx, %SHIFT_REG
sarl $2, %SHIFT_REG
# endif
/* Remove the leading bits. */
sarxl %SHIFT_REG, %eax, %eax
testl %eax, %eax
jz L(aligned_more)
tzcntl %eax, %eax
addq %rcx, %rdi
# ifdef USE_AS_WCSCHR
/* NB: Multiply wchar_t count by 4 to get the number of bytes. */
leaq (%rdi, %rax, 4), %rax
# else
addq %rdi, %rax
# endif
# ifndef USE_AS_STRCHRNUL
cmp (%rax), %CHAR_REG
cmovne %rdx, %rax
# endif
ret
END (STRCHR)
# endif
|
