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/* strrchr/wcsrchr 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 STRRCHR
# define STRRCHR __strrchr_evex
# endif
# define VMOVU vmovdqu64
# define VMOVA vmovdqa64
# ifdef USE_AS_WCSRCHR
# define VPBROADCAST vpbroadcastd
# define VPCMP vpcmpd
# define SHIFT_REG r8d
# else
# define VPBROADCAST vpbroadcastb
# define VPCMP vpcmpb
# define SHIFT_REG ecx
# endif
# define XMMZERO xmm16
# define YMMZERO ymm16
# define YMMMATCH ymm17
# define YMM1 ymm18
# define VEC_SIZE 32
.section .text.evex,"ax",@progbits
ENTRY (STRRCHR)
movl %edi, %ecx
/* Broadcast CHAR to YMMMATCH. */
VPBROADCAST %esi, %YMMMATCH
vpxorq %XMMZERO, %XMMZERO, %XMMZERO
/* Check if we may cross page boundary with one vector load. */
andl $(2 * VEC_SIZE - 1), %ecx
cmpl $VEC_SIZE, %ecx
ja L(cros_page_boundary)
VMOVU (%rdi), %YMM1
/* Each bit in K0 represents a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM1, %k0
/* Each bit in K1 represents a CHAR in YMM1. */
VPCMP $0, %YMMMATCH, %YMM1, %k1
kmovd %k0, %ecx
kmovd %k1, %eax
addq $VEC_SIZE, %rdi
testl %eax, %eax
jnz L(first_vec)
testl %ecx, %ecx
jnz L(return_null)
andq $-VEC_SIZE, %rdi
xorl %edx, %edx
jmp L(aligned_loop)
.p2align 4
L(first_vec):
/* Check if there is a null byte. */
testl %ecx, %ecx
jnz L(char_and_nul_in_first_vec)
/* Remember the match and keep searching. */
movl %eax, %edx
movq %rdi, %rsi
andq $-VEC_SIZE, %rdi
jmp L(aligned_loop)
.p2align 4
L(cros_page_boundary):
andl $(VEC_SIZE - 1), %ecx
andq $-VEC_SIZE, %rdi
# ifdef USE_AS_WCSRCHR
/* NB: Divide shift count by 4 since each bit in K1 represent 4
bytes. */
movl %ecx, %SHIFT_REG
sarl $2, %SHIFT_REG
# endif
VMOVA (%rdi), %YMM1
/* Each bit in K0 represents a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM1, %k0
/* Each bit in K1 represents a CHAR in YMM1. */
VPCMP $0, %YMMMATCH, %YMM1, %k1
kmovd %k0, %edx
kmovd %k1, %eax
shrxl %SHIFT_REG, %edx, %edx
shrxl %SHIFT_REG, %eax, %eax
addq $VEC_SIZE, %rdi
/* Check if there is a CHAR. */
testl %eax, %eax
jnz L(found_char)
testl %edx, %edx
jnz L(return_null)
jmp L(aligned_loop)
.p2align 4
L(found_char):
testl %edx, %edx
jnz L(char_and_nul)
/* Remember the match and keep searching. */
movl %eax, %edx
leaq (%rdi, %rcx), %rsi
.p2align 4
L(aligned_loop):
VMOVA (%rdi), %YMM1
addq $VEC_SIZE, %rdi
/* Each bit in K0 represents a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM1, %k0
/* Each bit in K1 represents a CHAR in YMM1. */
VPCMP $0, %YMMMATCH, %YMM1, %k1
kmovd %k0, %ecx
kmovd %k1, %eax
orl %eax, %ecx
jnz L(char_nor_null)
VMOVA (%rdi), %YMM1
add $VEC_SIZE, %rdi
/* Each bit in K0 represents a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM1, %k0
/* Each bit in K1 represents a CHAR in YMM1. */
VPCMP $0, %YMMMATCH, %YMM1, %k1
kmovd %k0, %ecx
kmovd %k1, %eax
orl %eax, %ecx
jnz L(char_nor_null)
VMOVA (%rdi), %YMM1
addq $VEC_SIZE, %rdi
/* Each bit in K0 represents a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM1, %k0
/* Each bit in K1 represents a CHAR in YMM1. */
VPCMP $0, %YMMMATCH, %YMM1, %k1
kmovd %k0, %ecx
kmovd %k1, %eax
orl %eax, %ecx
jnz L(char_nor_null)
VMOVA (%rdi), %YMM1
addq $VEC_SIZE, %rdi
/* Each bit in K0 represents a null byte in YMM1. */
VPCMP $0, %YMMZERO, %YMM1, %k0
/* Each bit in K1 represents a CHAR in YMM1. */
VPCMP $0, %YMMMATCH, %YMM1, %k1
kmovd %k0, %ecx
kmovd %k1, %eax
orl %eax, %ecx
jz L(aligned_loop)
.p2align 4
L(char_nor_null):
/* Find a CHAR or a null byte in a loop. */
testl %eax, %eax
jnz L(match)
L(return_value):
testl %edx, %edx
jz L(return_null)
movl %edx, %eax
movq %rsi, %rdi
bsrl %eax, %eax
# ifdef USE_AS_WCSRCHR
/* 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
ret
.p2align 4
L(match):
/* Find a CHAR. Check if there is a null byte. */
kmovd %k0, %ecx
testl %ecx, %ecx
jnz L(find_nul)
/* Remember the match and keep searching. */
movl %eax, %edx
movq %rdi, %rsi
jmp L(aligned_loop)
.p2align 4
L(find_nul):
/* Mask out any matching bits after the null byte. */
movl %ecx, %r8d
subl $1, %r8d
xorl %ecx, %r8d
andl %r8d, %eax
testl %eax, %eax
/* If there is no CHAR here, return the remembered one. */
jz L(return_value)
bsrl %eax, %eax
# ifdef USE_AS_WCSRCHR
/* 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
ret
.p2align 4
L(char_and_nul):
/* Find both a CHAR and a null byte. */
addq %rcx, %rdi
movl %edx, %ecx
L(char_and_nul_in_first_vec):
/* Mask out any matching bits after the null byte. */
movl %ecx, %r8d
subl $1, %r8d
xorl %ecx, %r8d
andl %r8d, %eax
testl %eax, %eax
/* Return null pointer if the null byte comes first. */
jz L(return_null)
bsrl %eax, %eax
# ifdef USE_AS_WCSRCHR
/* 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
ret
.p2align 4
L(return_null):
xorl %eax, %eax
ret
END (STRRCHR)
#endif
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