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
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
|
/* Measure memmem functions.
Copyright (C) 2013-2019 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/>. */
#define TEST_MAIN
#define TEST_NAME "memmem"
#define BUF1PAGES 20
#define ITERATIONS 100
#include "bench-string.h"
typedef char *(*proto_t) (const void *, size_t, const void *, size_t);
void *
basic_memmem (const void *haystack, size_t hs_len, const void *needle,
size_t ne_len)
{
const char *hs = haystack;
const char *ne = needle;
if (ne_len == 0)
return (void *)hs;
int i;
int c = ne[0];
const char *end = hs + hs_len - ne_len;
for ( ; hs <= end; hs++)
{
if (hs[0] != c)
continue;
for (i = ne_len - 1; i != 0; i--)
if (hs[i] != ne[i])
break;
if (i == 0)
return (void *)hs;
}
return NULL;
}
#define RETURN_TYPE void *
#define AVAILABLE(h, h_l, j, n_l) ((j) <= (h_l) - (n_l))
#define FASTSEARCH(S,C,N) (void*) memchr ((void *)(S), (C), (N))
#include "../string/str-two-way.h"
void *
twoway_memmem (const void *haystack_start, size_t haystack_len,
const void *needle_start, size_t needle_len)
{
/* Abstract memory is considered to be an array of 'unsigned char' values,
not an array of 'char' values. See ISO C 99 section 6.2.6.1. */
const unsigned char *haystack = (const unsigned char *) haystack_start;
const unsigned char *needle = (const unsigned char *) needle_start;
if (needle_len == 0)
/* The first occurrence of the empty string is deemed to occur at
the beginning of the string. */
return (void *) haystack;
/* Sanity check, otherwise the loop might search through the whole
memory. */
if (__glibc_unlikely (haystack_len < needle_len))
return NULL;
/* Use optimizations in memchr when possible, to reduce the search
size of haystack using a linear algorithm with a smaller
coefficient. However, avoid memchr for long needles, since we
can often achieve sublinear performance. */
if (needle_len < LONG_NEEDLE_THRESHOLD)
{
haystack = memchr (haystack, *needle, haystack_len);
if (!haystack || __builtin_expect (needle_len == 1, 0))
return (void *) haystack;
haystack_len -= haystack - (const unsigned char *) haystack_start;
if (haystack_len < needle_len)
return NULL;
/* Check whether we have a match. This improves performance since we
avoid the initialization overhead of the two-way algorithm. */
if (memcmp (haystack, needle, needle_len) == 0)
return (void *) haystack;
return two_way_short_needle (haystack, haystack_len, needle, needle_len);
}
else
return two_way_long_needle (haystack, haystack_len, needle, needle_len);
}
IMPL (memmem, 1)
IMPL (twoway_memmem, 0)
IMPL (basic_memmem, 0)
static void
do_one_test (impl_t *impl, const void *haystack, size_t haystack_len,
const void *needle, size_t needle_len, const void *expected)
{
size_t i, iters = INNER_LOOP_ITERS_SMALL;
timing_t start, stop, cur;
TIMING_NOW (start);
for (i = 0; i < iters; ++i)
{
CALL (impl, haystack, haystack_len, needle, needle_len);
}
TIMING_NOW (stop);
TIMING_DIFF (cur, start, stop);
TIMING_PRINT_MEAN ((double) cur, (double) iters);
}
static void
do_test (const char *str, size_t len, size_t idx)
{
char tmpbuf[len];
memcpy (tmpbuf, buf1 + idx, len);
memcpy (buf1 + idx, str, len);
printf ("String %s, offset %zd:", str, idx);
FOR_EACH_IMPL (impl, 0)
do_one_test (impl, buf1, BUF1PAGES * page_size, str, len, buf1 + idx);
memcpy (buf1 + idx, tmpbuf, len);
putchar ('\n');
}
static void
do_random_tests (void)
{
for (size_t n = 0; n < ITERATIONS; ++n)
{
char tmpbuf[32];
size_t shift = random () % 11;
size_t rel = random () % ((2 << (shift + 1)) * 64);
size_t idx = MIN ((2 << shift) * 64 + rel, BUF1PAGES * page_size - 2);
size_t len = random () % (sizeof (tmpbuf) - 1) + 1;
len = MIN (len, BUF1PAGES * page_size - idx - 1);
memcpy (tmpbuf, buf1 + idx, len);
for (size_t i = random () % len / 2 + 1; i > 0; --i)
{
size_t off = random () % len;
char ch = '0' + random () % 10;
buf1[idx + off] = ch;
}
printf ("String %.*s, offset %zd:", (int) len, buf1 + idx, idx);
FOR_EACH_IMPL (impl, 0)
do_one_test (impl, buf1, BUF1PAGES * page_size, buf1 + idx, len,
buf1 + idx);
putchar ('\n');
memcpy (buf1 + idx, tmpbuf, len);
}
}
static const char *const strs[] =
{
"00000", "00112233", "0123456789", "0000111100001111",
"00000111110000022222", "012345678901234567890",
"abc0", "aaaa0", "abcabc0"
};
int
test_main (void)
{
size_t i;
test_init ();
printf ("%23s", "");
FOR_EACH_IMPL (impl, 0)
printf ("\t%s", impl->name);
putchar ('\n');
for (i = 0; i < BUF1PAGES * page_size; ++i)
buf1[i] = 60 + random () % 32;
for (i = 0; i < sizeof (strs) / sizeof (strs[0]); ++i)
for (size_t j = 0; j < 120; j += 7)
{
size_t len = strlen (strs[i]);
do_test (strs[i], len, j);
}
do_random_tests ();
return ret;
}
#include <support/test-driver.c>
|
GitWeb