benchtests/bench-memmem.c

   1 /* Measure memmem functions.
   2    Copyright (C) 2013-2020 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #define TEST_MAIN
  20 #define TEST_NAME "memmem"
  21 #define BUF1PAGES 20
  22 #define ITERATIONS 100
  23 #include "bench-string.h"
  24
  25 typedef char *(*proto_t) (const void *, size_t, const void *, size_t);
  26
  27 void *
  28 basic_memmem (const void *haystack, size_t hs_len, const void *needle,
  29               size_t ne_len)
  30 {
  31   const char *hs = haystack;
  32   const char *ne = needle;
  33
  34   if (ne_len == 0)
  35     return (void *)hs;
  36   int i;
  37   int c = ne[0];
  38   const char *end = hs + hs_len - ne_len;
  39
  40   for ( ; hs <= end; hs++)
  41   {
  42     if (hs[0] != c)
  43       continue;
  44     for (i = ne_len - 1; i != 0; i--)
  45       if (hs[i] != ne[i])
  46         break;
  47     if (i == 0)
  48       return (void *)hs;
  49   }
  50
  51   return NULL;
  52 }
  53
  54 #define RETURN_TYPE void *
  55 #define AVAILABLE(h, h_l, j, n_l) ((j) <= (h_l) - (n_l))
  56 #define FASTSEARCH(S,C,N) (void*) memchr ((void *)(S), (C), (N))
  57 #include "../string/str-two-way.h"
  58
  59 void *
  60 twoway_memmem (const void *haystack_start, size_t haystack_len,
  61                const void *needle_start, size_t needle_len)
  62 {
  63   /* Abstract memory is considered to be an array of 'unsigned char' values,
  64      not an array of 'char' values.  See ISO C 99 section 6.2.6.1.  */
  65   const unsigned char *haystack = (const unsigned char *) haystack_start;
  66   const unsigned char *needle = (const unsigned char *) needle_start;
  67
  68   if (needle_len == 0)
  69     /* The first occurrence of the empty string is deemed to occur at
  70        the beginning of the string.  */
  71     return (void *) haystack;
  72
  73   /* Sanity check, otherwise the loop might search through the whole
  74      memory.  */
  75   if (__glibc_unlikely (haystack_len < needle_len))
  76     return NULL;
  77
  78   /* Use optimizations in memchr when possible, to reduce the search
  79      size of haystack using a linear algorithm with a smaller
  80      coefficient.  However, avoid memchr for long needles, since we
  81      can often achieve sublinear performance.  */
  82   if (needle_len < LONG_NEEDLE_THRESHOLD)
  83     {
  84       haystack = memchr (haystack, *needle, haystack_len);
  85       if (!haystack || __builtin_expect (needle_len == 1, 0))
  86         return (void *) haystack;
  87       haystack_len -= haystack - (const unsigned char *) haystack_start;
  88       if (haystack_len < needle_len)
  89         return NULL;
  90       /* Check whether we have a match.  This improves performance since we
  91          avoid the initialization overhead of the two-way algorithm.  */
  92       if (memcmp (haystack, needle, needle_len) == 0)
  93         return (void *) haystack;
  94       return two_way_short_needle (haystack, haystack_len, needle, needle_len);
  95     }
  96   else
  97     return two_way_long_needle (haystack, haystack_len, needle, needle_len);
  98 }
  99
 100 IMPL (memmem, 1)
 101 IMPL (twoway_memmem, 0)
 102 IMPL (basic_memmem, 0)
 103
 104 static void
 105 do_one_test (impl_t *impl, const void *haystack, size_t haystack_len,
 106              const void *needle, size_t needle_len, const void *expected)
 107 {
 108   size_t i, iters = INNER_LOOP_ITERS_SMALL;
 109   timing_t start, stop, cur;
 110
 111   TIMING_NOW (start);
 112   for (i = 0; i < iters; ++i)
 113     {
 114       CALL (impl, haystack, haystack_len, needle, needle_len);
 115     }
 116   TIMING_NOW (stop);
 117
 118   TIMING_DIFF (cur, start, stop);
 119
 120   TIMING_PRINT_MEAN ((double) cur, (double) iters);
 121 }
 122
 123 static void
 124 do_test (const char *str, size_t len, size_t idx)
 125 {
 126   char tmpbuf[len];
 127
 128   memcpy (tmpbuf, buf1 + idx, len);
 129   memcpy (buf1 + idx, str, len);
 130
 131   printf ("String %s, offset %zd:", str, idx);
 132
 133   FOR_EACH_IMPL (impl, 0)
 134     do_one_test (impl, buf1, BUF1PAGES * page_size, str, len, buf1 + idx);
 135
 136   memcpy (buf1 + idx, tmpbuf, len);
 137
 138   putchar ('\n');
 139 }
 140
 141 static void
 142 do_random_tests (void)
 143 {
 144   for (size_t n = 0; n < ITERATIONS; ++n)
 145     {
 146       char tmpbuf[32];
 147
 148       size_t shift = random () % 11;
 149       size_t rel = random () % ((2 << (shift + 1)) * 64);
 150       size_t idx = MIN ((2 << shift) * 64 + rel, BUF1PAGES * page_size - 2);
 151       size_t len = random () % (sizeof (tmpbuf) - 1) + 1;
 152       len = MIN (len, BUF1PAGES * page_size - idx - 1);
 153       memcpy (tmpbuf, buf1 + idx, len);
 154       for (size_t i = random () % len / 2 + 1; i > 0; --i)
 155         {
 156           size_t off = random () % len;
 157           char ch = '0' + random () % 10;
 158
 159           buf1[idx + off] = ch;
 160         }
 161
 162       printf ("String %.*s, offset %zd:", (int) len, buf1 + idx, idx);
 163
 164       FOR_EACH_IMPL (impl, 0)
 165         do_one_test (impl, buf1, BUF1PAGES * page_size, buf1 + idx, len,
 166                      buf1 + idx);
 167
 168       putchar ('\n');
 169
 170       memcpy (buf1 + idx, tmpbuf, len);
 171     }
 172 }
 173
 174 static const char *const strs[] =
 175   {
 176     "00000", "00112233", "0123456789", "0000111100001111",
 177     "00000111110000022222", "012345678901234567890",
 178     "abc0", "aaaa0", "abcabc0"
 179   };
 180
 181
 182 int
 183 test_main (void)
 184 {
 185   size_t i;
 186
 187   test_init ();
 188
 189   printf ("%23s", "");
 190   FOR_EACH_IMPL (impl, 0)
 191     printf ("\t%s", impl->name);
 192   putchar ('\n');
 193
 194   for (i = 0; i < BUF1PAGES * page_size; ++i)
 195     buf1[i] = 60 + random () % 32;
 196
 197   for (i = 0; i < sizeof (strs) / sizeof (strs[0]); ++i)
 198     for (size_t j = 0; j < 120; j += 7)
 199       {
 200         size_t len = strlen (strs[i]);
 201
 202         do_test (strs[i], len, j);
 203       }
 204
 205   do_random_tests ();
 206   return ret;
 207 }
 208
 209 #include <support/test-driver.c>