/* strrchr optimized with SSE2.
Copyright (C) 2017-2024 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
. */
#include
/* ISA level >= 2 because there are no {wcs|str}rchr-sse4
implementations. */
#if ISA_SHOULD_BUILD (2)
# include
# ifndef STRRCHR
# define STRRCHR __strrchr_sse2
# endif
# ifdef USE_AS_WCSRCHR
# define PCMPEQ pcmpeqd
# define CHAR_SIZE 4
# define PMINU pminud
# else
# define PCMPEQ pcmpeqb
# define CHAR_SIZE 1
# define PMINU pminub
# endif
# define PAGE_SIZE 4096
# define VEC_SIZE 16
.text
ENTRY(STRRCHR)
movd %esi, %xmm0
movq %rdi, %rax
andl $(PAGE_SIZE - 1), %eax
# ifndef USE_AS_WCSRCHR
punpcklbw %xmm0, %xmm0
punpcklwd %xmm0, %xmm0
# endif
pshufd $0, %xmm0, %xmm0
cmpl $(PAGE_SIZE - VEC_SIZE), %eax
ja L(cross_page)
L(cross_page_continue):
movups (%rdi), %xmm1
pxor %xmm2, %xmm2
PCMPEQ %xmm1, %xmm2
pmovmskb %xmm2, %ecx
testl %ecx, %ecx
jz L(aligned_more)
PCMPEQ %xmm0, %xmm1
pmovmskb %xmm1, %eax
leal -1(%rcx), %edx
xorl %edx, %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):
ret
/* Returns for first vec x1/x2 have hard coded backward search
path for earlier matches. */
.p2align 4
L(first_vec_x0_test):
PCMPEQ %xmm0, %xmm1
pmovmskb %xmm1, %eax
testl %eax, %eax
jz L(ret0)
bsrl %eax, %eax
addq %r8, %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
ret
.p2align 4
L(first_vec_x1):
PCMPEQ %xmm0, %xmm2
pmovmskb %xmm2, %eax
leal -1(%rcx), %edx
xorl %edx, %ecx
andl %ecx, %eax
jz L(first_vec_x0_test)
bsrl %eax, %eax
leaq (VEC_SIZE)(%rdi, %rax), %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
ret
.p2align 4
L(first_vec_x1_test):
PCMPEQ %xmm0, %xmm2
pmovmskb %xmm2, %eax
testl %eax, %eax
jz L(first_vec_x0_test)
bsrl %eax, %eax
leaq (VEC_SIZE)(%rdi, %rax), %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
ret
.p2align 4
L(first_vec_x2):
PCMPEQ %xmm0, %xmm3
pmovmskb %xmm3, %eax
leal -1(%rcx), %edx
xorl %edx, %ecx
andl %ecx, %eax
jz L(first_vec_x1_test)
bsrl %eax, %eax
leaq (VEC_SIZE * 2)(%rdi, %rax), %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
ret
.p2align 4
L(aligned_more):
/* Save original pointer if match was in VEC 0. */
movq %rdi, %r8
andq $-VEC_SIZE, %rdi
movaps VEC_SIZE(%rdi), %xmm2
pxor %xmm3, %xmm3
PCMPEQ %xmm2, %xmm3
pmovmskb %xmm3, %ecx
testl %ecx, %ecx
jnz L(first_vec_x1)
movaps (VEC_SIZE * 2)(%rdi), %xmm3
pxor %xmm4, %xmm4
PCMPEQ %xmm3, %xmm4
pmovmskb %xmm4, %ecx
testl %ecx, %ecx
jnz L(first_vec_x2)
addq $VEC_SIZE, %rdi
/* Save pointer again before realigning. */
movq %rdi, %rsi
andq $-(VEC_SIZE * 2), %rdi
.p2align 4
L(first_loop):
/* Do 2x VEC at a time. */
movaps (VEC_SIZE * 2)(%rdi), %xmm4
movaps (VEC_SIZE * 3)(%rdi), %xmm5
/* Since SSE2 no pminud so wcsrchr needs separate logic for
detecting zero. Note if this is found to be a bottleneck it
may be worth adding an SSE4.1 wcsrchr implementation. */
# ifdef USE_AS_WCSRCHR
movaps %xmm5, %xmm6
pxor %xmm8, %xmm8
PCMPEQ %xmm8, %xmm5
PCMPEQ %xmm4, %xmm8
por %xmm5, %xmm8
# else
movaps %xmm5, %xmm6
PMINU %xmm4, %xmm5
# endif
movaps %xmm4, %xmm9
PCMPEQ %xmm0, %xmm4
PCMPEQ %xmm0, %xmm6
movaps %xmm6, %xmm7
por %xmm4, %xmm6
# ifndef USE_AS_WCSRCHR
pxor %xmm8, %xmm8
PCMPEQ %xmm5, %xmm8
# endif
pmovmskb %xmm8, %ecx
pmovmskb %xmm6, %eax
addq $(VEC_SIZE * 2), %rdi
/* Use `addl` 1) so we can undo it with `subl` and 2) it can
macro-fuse with `jz`. */
addl %ecx, %eax
jz L(first_loop)
/* Check if there is zero match. */
testl %ecx, %ecx
jz L(second_loop_match)
/* Check if there was a match in last iteration. */
subl %ecx, %eax
jnz L(new_match)
L(first_loop_old_match):
PCMPEQ %xmm0, %xmm2
PCMPEQ %xmm0, %xmm3
pmovmskb %xmm2, %ecx
pmovmskb %xmm3, %eax
addl %eax, %ecx
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. */
sall $16, %eax
orl %ecx, %eax
bsrl %eax, %eax
addq %rsi, %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
ret
.p2align 4
L(new_match):
pxor %xmm6, %xmm6
PCMPEQ %xmm9, %xmm6
pmovmskb %xmm6, %eax
sall $16, %ecx
orl %eax, %ecx
/* We can't reuse either of the old comparisons as since we mask
of zeros after first zero (instead of using the full
comparison) we can't guarantee no interference between match
after end of string and valid match. */
pmovmskb %xmm4, %eax
pmovmskb %xmm7, %edx
sall $16, %edx
orl %edx, %eax
leal -1(%ecx), %edx
xorl %edx, %ecx
andl %ecx, %eax
jz L(first_loop_old_match)
bsrl %eax, %eax
addq %rdi, %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
ret
/* Save minimum state for getting most recent match. We can
throw out all previous work. */
.p2align 4
L(second_loop_match):
movq %rdi, %rsi
movaps %xmm4, %xmm2
movaps %xmm7, %xmm3
.p2align 4
L(second_loop):
movaps (VEC_SIZE * 2)(%rdi), %xmm4
movaps (VEC_SIZE * 3)(%rdi), %xmm5
/* Since SSE2 no pminud so wcsrchr needs separate logic for
detecting zero. Note if this is found to be a bottleneck it
may be worth adding an SSE4.1 wcsrchr implementation. */
# ifdef USE_AS_WCSRCHR
movaps %xmm5, %xmm6
pxor %xmm8, %xmm8
PCMPEQ %xmm8, %xmm5
PCMPEQ %xmm4, %xmm8
por %xmm5, %xmm8
# else
movaps %xmm5, %xmm6
PMINU %xmm4, %xmm5
# endif
movaps %xmm4, %xmm9
PCMPEQ %xmm0, %xmm4
PCMPEQ %xmm0, %xmm6
movaps %xmm6, %xmm7
por %xmm4, %xmm6
# ifndef USE_AS_WCSRCHR
pxor %xmm8, %xmm8
PCMPEQ %xmm5, %xmm8
# endif
pmovmskb %xmm8, %ecx
pmovmskb %xmm6, %eax
addq $(VEC_SIZE * 2), %rdi
/* Either null term or new occurrence of CHAR. */
addl %ecx, %eax
jz L(second_loop)
/* No null term so much be new occurrence of CHAR. */
testl %ecx, %ecx
jz L(second_loop_match)
subl %ecx, %eax
jnz L(second_loop_new_match)
L(second_loop_old_match):
pmovmskb %xmm2, %ecx
pmovmskb %xmm3, %eax
sall $16, %eax
orl %ecx, %eax
bsrl %eax, %eax
addq %rsi, %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
ret
.p2align 4
L(second_loop_new_match):
pxor %xmm6, %xmm6
PCMPEQ %xmm9, %xmm6
pmovmskb %xmm6, %eax
sall $16, %ecx
orl %eax, %ecx
/* We can't reuse either of the old comparisons as since we mask
of zeros after first zero (instead of using the full
comparison) we can't guarantee no interference between match
after end of string and valid match. */
pmovmskb %xmm4, %eax
pmovmskb %xmm7, %edx
sall $16, %edx
orl %edx, %eax
leal -1(%ecx), %edx
xorl %edx, %ecx
andl %ecx, %eax
jz L(second_loop_old_match)
bsrl %eax, %eax
addq %rdi, %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
ret
.p2align 4,, 4
L(cross_page):
movq %rdi, %rsi
andq $-VEC_SIZE, %rsi
movaps (%rsi), %xmm1
pxor %xmm2, %xmm2
PCMPEQ %xmm1, %xmm2
pmovmskb %xmm2, %edx
movl %edi, %ecx
andl $(VEC_SIZE - 1), %ecx
sarl %cl, %edx
jz L(cross_page_continue)
PCMPEQ %xmm0, %xmm1
pmovmskb %xmm1, %eax
sarl %cl, %eax
leal -1(%rdx), %ecx
xorl %edx, %ecx
andl %ecx, %eax
jz L(ret1)
bsrl %eax, %eax
addq %rdi, %rax
# ifdef USE_AS_WCSRCHR
andq $-CHAR_SIZE, %rax
# endif
L(ret1):
ret
END(STRRCHR)
#endif