benchtests/bench-strcmp.c

   1 /* Measure strcmp and wcscmp functions.
   2    Copyright (C) 2013-2021 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 #ifdef WIDE
  21 # define TEST_NAME "wcscmp"
  22 #else
  23 # define TEST_NAME "strcmp"
  24 #endif
  25 #include "bench-string.h"
  26
  27 #ifdef WIDE
  28 # define L(str) L##str
  29 # define SIMPLE_STRCMP simple_wcscmp
  30 # define CHARBYTESLOG 2
  31 # define MIDCHAR 0x7fffffff
  32 # define LARGECHAR 0xfffffffe
  33
  34 /* Wcscmp uses signed semantics for comparison, not unsigned */
  35 /* Avoid using substraction since possible overflow */
  36
  37 int
  38 simple_wcscmp (const wchar_t *s1, const wchar_t *s2)
  39 {
  40   wchar_t c1, c2;
  41   do
  42     {
  43       c1 = *s1++;
  44       c2 = *s2++;
  45       if (c2 == L'\0')
  46       return c1 - c2;
  47     }
  48   while (c1 == c2);
  49
  50   return c1 < c2 ? -1 : 1;
  51 }
  52
  53 #else
  54 # include <limits.h>
  55
  56 # define L(str) str
  57 # define SIMPLE_STRCMP simple_strcmp
  58 # define CHARBYTESLOG 0
  59 # define MIDCHAR 0x7f
  60 # define LARGECHAR 0xfe
  61
  62 /* Strcmp uses unsigned semantics for comparison. */
  63 int
  64 simple_strcmp (const char *s1, const char *s2)
  65 {
  66   int ret;
  67
  68   while ((ret = *(unsigned char *) s1 - *(unsigned char*) s2++) == 0 && *s1++);
  69   return ret;
  70 }
  71
  72 #endif
  73
  74 # include "json-lib.h"
  75
  76 typedef int (*proto_t) (const CHAR *, const CHAR *);
  77
  78 IMPL (SIMPLE_STRCMP, 1)
  79 IMPL (STRCMP, 1)
  80
  81 static void
  82 do_one_test (json_ctx_t *json_ctx, impl_t *impl,
  83              const CHAR *s1, const CHAR *s2,
  84              int exp_result)
  85 {
  86   size_t i, iters = INNER_LOOP_ITERS8;
  87   timing_t start, stop, cur;
  88
  89   TIMING_NOW (start);
  90   for (i = 0; i < iters; ++i)
  91     {
  92       CALL (impl, s1, s2);
  93     }
  94   TIMING_NOW (stop);
  95
  96   TIMING_DIFF (cur, start, stop);
  97
  98   json_element_double (json_ctx, (double) cur / (double) iters);
  99 }
 100
 101 static void
 102 do_test (json_ctx_t *json_ctx, size_t align1, size_t align2, size_t len, int
 103          max_char, int exp_result)
 104 {
 105   size_t i;
 106
 107   CHAR *s1, *s2;
 108
 109   if (len == 0)
 110     return;
 111
 112   align1 &= 63;
 113   if (align1 + (len + 1) * CHARBYTES >= page_size)
 114     return;
 115
 116   align2 &= 63;
 117   if (align2 + (len + 1) * CHARBYTES >= page_size)
 118     return;
 119
 120   /* Put them close to the end of page.  */
 121   i = align1 + CHARBYTES * (len + 2);
 122   s1 = (CHAR *) (buf1 + ((page_size - i) / 16 * 16) + align1);
 123   i = align2 + CHARBYTES * (len + 2);
 124   s2 = (CHAR *) (buf2 + ((page_size - i) / 16 * 16)  + align2);
 125
 126   for (i = 0; i < len; i++)
 127     s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % max_char;
 128
 129   s1[len] = s2[len] = 0;
 130   s1[len + 1] = 23;
 131   s2[len + 1] = 24 + exp_result;
 132   s2[len - 1] -= exp_result;
 133
 134   json_element_object_begin (json_ctx);
 135   json_attr_uint (json_ctx, "length", (double) len);
 136   json_attr_uint (json_ctx, "align1", (double) align1);
 137   json_attr_uint (json_ctx, "align2", (double) align2);
 138   json_array_begin (json_ctx, "timings");
 139
 140   FOR_EACH_IMPL (impl, 0)
 141     do_one_test (json_ctx, impl, s1, s2, exp_result);
 142
 143   json_array_end (json_ctx);
 144   json_element_object_end (json_ctx);
 145 }
 146
 147 static void
 148 do_one_test_page_boundary (json_ctx_t *json_ctx, CHAR *s1, CHAR *s2,
 149                            size_t align1, size_t align2, size_t len,
 150                            int exp_result)
 151 {
 152   json_element_object_begin (json_ctx);
 153   json_attr_uint (json_ctx, "length", (double) len);
 154   json_attr_uint (json_ctx, "align1", (double) align1);
 155   json_attr_uint (json_ctx, "align2", (double) align2);
 156   json_array_begin (json_ctx, "timings");
 157   FOR_EACH_IMPL (impl, 0)
 158     do_one_test (json_ctx, impl, s1, s2, exp_result);
 159   json_array_end (json_ctx);
 160   json_element_object_end (json_ctx);
 161 }
 162
 163 static void
 164 do_test_page_boundary (json_ctx_t *json_ctx)
 165 {
 166   /* To trigger bug 25933, we need a size that is equal to the vector
 167      length times 4. In the case of AVX2 for Intel, we need 32 * 4.  We
 168      make this test generic and run it for all architectures as additional
 169      boundary testing for such related algorithms.  */
 170   size_t size = 32 * 4;
 171   size_t len;
 172   CHAR *s1 = (CHAR *) (buf1 + (BUF1PAGES - 1) * page_size);
 173   CHAR *s2 = (CHAR *) (buf2 + (BUF1PAGES - 1) * page_size);
 174   int exp_result;
 175
 176   memset (s1, 'a', page_size);
 177   memset (s2, 'a', page_size);
 178
 179   s1[(page_size / CHARBYTES) - 1] = (CHAR) 0;
 180   s2[(page_size / CHARBYTES) - 1] = (CHAR) 0;
 181
 182   /* Iterate over a size that is just below where we expect the bug to
 183      trigger up to the size we expect will trigger the bug e.g. [99-128].
 184      Likewise iterate the start of two strings between 30 and 31 bytes
 185      away from the boundary to simulate alignment changes.  */
 186   for (size_t s = 99; s <= size; s++)
 187     for (size_t s1a = 30; s1a < 32; s1a++)
 188       for (size_t s2a = 30; s2a < 32; s2a++)
 189         {
 190           size_t align1 = (page_size / CHARBYTES - s) - s1a;
 191           size_t align2 = (page_size / CHARBYTES - s) - s2a;
 192           CHAR *s1p = s1 + align1;
 193           CHAR *s2p = s2 + align2;
 194           len = (page_size / CHARBYTES) - 1 - align1;
 195           exp_result = SIMPLE_STRCMP (s1p, s2p);
 196           do_one_test_page_boundary (json_ctx, s1p, s2p, align1, align2,
 197                                      len, exp_result);
 198         }
 199 }
 200
 201 int
 202 test_main (void)
 203 {
 204   json_ctx_t json_ctx;
 205   size_t i;
 206
 207   test_init ();
 208
 209   json_init (&json_ctx, 0, stdout);
 210
 211   json_document_begin (&json_ctx);
 212   json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
 213
 214   json_attr_object_begin (&json_ctx, "functions");
 215   json_attr_object_begin (&json_ctx, TEST_NAME);
 216   json_attr_string (&json_ctx, "bench-variant", "default");
 217
 218   json_array_begin (&json_ctx, "ifuncs");
 219   FOR_EACH_IMPL (impl, 0)
 220     json_element_string (&json_ctx, impl->name);
 221   json_array_end (&json_ctx);
 222
 223   json_array_begin (&json_ctx, "results");
 224
 225   for (i = 1; i < 32; ++i)
 226     {
 227       do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 0);
 228       do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 1);
 229       do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, -1);
 230     }
 231
 232   for (i = 1; i < 10 + CHARBYTESLOG; ++i)
 233     {
 234       do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 0);
 235       do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 0);
 236       do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 1);
 237       do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 1);
 238       do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, -1);
 239       do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, -1);
 240       do_test (&json_ctx, 0, CHARBYTES * i, 2 << i, MIDCHAR, 1);
 241       do_test (&json_ctx, CHARBYTES * i, CHARBYTES * (i + 1), 2 << i, LARGECHAR, 1);
 242     }
 243
 244   for (i = 1; i < 8; ++i)
 245     {
 246       do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i, MIDCHAR, 0);
 247       do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, 0);
 248       do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i, MIDCHAR, 1);
 249       do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, 1);
 250       do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i, MIDCHAR, -1);
 251       do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, -1);
 252     }
 253
 254   do_test_page_boundary (&json_ctx);
 255
 256   json_array_end (&json_ctx);
 257   json_attr_object_end (&json_ctx);
 258   json_attr_object_end (&json_ctx);
 259   json_document_end (&json_ctx);
 260
 261   return ret;
 262 }
 263
 264 #include <support/test-driver.c>