1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/* strcspn with SSE4.2 intrinsics
Copyright (C) 2009-2022 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/>. */
#include <nmmintrin.h>
#include <string.h>
#include "varshift.h"
/* We use 0x2:
_SIDD_SBYTE_OPS
| _SIDD_CMP_EQUAL_ANY
| _SIDD_POSITIVE_POLARITY
| _SIDD_LEAST_SIGNIFICANT
on pcmpistri to compare xmm/mem128
0 1 2 3 4 5 6 7 8 9 A B C D E F
X X X X X X X X X X X X X X X X
against xmm
0 1 2 3 4 5 6 7 8 9 A B C D E F
A A A A A A A A A A A A A A A A
to find out if the first 16byte data element has any byte A and
the offset of the first byte. There are 3 cases:
1. The first 16byte data element has the byte A at the offset X.
2. The first 16byte data element has EOS and doesn't have the byte A.
3. The first 16byte data element is valid and doesn't have the byte A.
Here is the table of ECX, CFlag, ZFlag and SFlag for 2 cases:
1 X 1 0/1 0
2 16 0 1 0
3 16 0 0 0
We exit from the loop for cases 1 and 2 with jbe which branches
when either CFlag or ZFlag is 1. If CFlag == 1, ECX has the offset
X for case 1. */
#ifndef STRCSPN_SSE2
# define STRCSPN_SSE2 __strcspn_sse2
# define STRCSPN_SSE42 __strcspn_sse42
#endif
#ifdef USE_AS_STRPBRK
# define RETURN(val1, val2) return val1
#else
# define RETURN(val1, val2) return val2
#endif
extern
#ifdef USE_AS_STRPBRK
char *
#else
size_t
#endif
STRCSPN_SSE2 (const char *, const char *) attribute_hidden;
#ifdef USE_AS_STRPBRK
char *
#else
size_t
#endif
__attribute__ ((section (".text.sse4.2")))
STRCSPN_SSE42 (const char *s, const char *a)
{
if (*a == 0)
RETURN (NULL, strlen (s));
const char *aligned;
__m128i mask;
int offset = (int) ((size_t) a & 15);
if (offset != 0)
{
/* Load masks. */
aligned = (const char *) ((size_t) a & -16L);
__m128i mask0 = _mm_load_si128 ((__m128i *) aligned);
mask = __m128i_shift_right (mask0, offset);
/* Find where the NULL terminator is. */
int length = _mm_cmpistri (mask, mask, 0x3a);
if (length == 16 - offset)
{
/* There is no NULL terminator. */
__m128i mask1 = _mm_load_si128 ((__m128i *) (aligned + 16));
int index = _mm_cmpistri (mask1, mask1, 0x3a);
length += index;
/* Don't use SSE4.2 if the length of A > 16. */
if (length > 16)
return STRCSPN_SSE2 (s, a);
if (index != 0)
{
/* Combine mask0 and mask1. We could play games with
palignr, but frankly this data should be in L1 now
so do the merge via an unaligned load. */
mask = _mm_loadu_si128 ((__m128i *) a);
}
}
}
else
{
/* A is aligned. */
mask = _mm_load_si128 ((__m128i *) a);
/* Find where the NULL terminator is. */
int length = _mm_cmpistri (mask, mask, 0x3a);
if (length == 16)
{
/* There is no NULL terminator. Don't use SSE4.2 if the length
of A > 16. */
if (a[16] != 0)
return STRCSPN_SSE2 (s, a);
}
}
offset = (int) ((size_t) s & 15);
if (offset != 0)
{
/* Check partial string. */
aligned = (const char *) ((size_t) s & -16L);
__m128i value = _mm_load_si128 ((__m128i *) aligned);
value = __m128i_shift_right (value, offset);
int length = _mm_cmpistri (mask, value, 0x2);
/* No need to check ZFlag since ZFlag is always 1. */
int cflag = _mm_cmpistrc (mask, value, 0x2);
if (cflag)
RETURN ((char *) (s + length), length);
/* Find where the NULL terminator is. */
int index = _mm_cmpistri (value, value, 0x3a);
if (index < 16 - offset)
RETURN (NULL, index);
aligned += 16;
}
else
aligned = s;
while (1)
{
__m128i value = _mm_load_si128 ((__m128i *) aligned);
int index = _mm_cmpistri (mask, value, 0x2);
int cflag = _mm_cmpistrc (mask, value, 0x2);
int zflag = _mm_cmpistrz (mask, value, 0x2);
if (cflag)
RETURN ((char *) (aligned + index), (size_t) (aligned + index - s));
if (zflag)
RETURN (NULL,
/* Find where the NULL terminator is. */
(size_t) (aligned + _mm_cmpistri (value, value, 0x3a) - s));
aligned += 16;
}
}
|
