benchtests/bench-strcmp.c

   1 /* Measure strcmp and wcscmp functions.
   2    Copyright (C) 2013-2022 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,
 103          int max_char, int exp_result, int at_end)
 104 {
 105   size_t i;
 106
 107   CHAR *s1, *s2;
 108
 109   if (len == 0)
 110     return;
 111
 112   align1 &= ~(CHARBYTES - 1);
 113   align2 &= ~(CHARBYTES - 1);
 114
 115   align1 &= (getpagesize () - 1);
 116   if (align1 + (len + 1) * CHARBYTES >= page_size)
 117     return;
 118
 119   align2 &= (getpagesize () - 1);
 120   if (align2 + (len + 1) * CHARBYTES >= page_size)
 121     return;
 122
 123   /* Put them close to the end of page.  */
 124   if (at_end)
 125     {
 126       i = align1 + CHARBYTES * (len + 2);
 127       align1 = ((page_size - i) / 16 * 16) + align1;
 128       i = align2 + CHARBYTES * (len + 2);
 129       align2 = ((page_size - i) / 16 * 16) + align2;
 130     }
 131
 132   s1 = (CHAR *)(buf1 + align1);
 133   s2 = (CHAR *)(buf2 + align2);
 134
 135   for (i = 0; i < len; i++)
 136     s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % max_char;
 137
 138   s1[len] = s2[len] = 0;
 139   s1[len + 1] = 23;
 140   s2[len + 1] = 24 + exp_result;
 141   s2[len - 1] -= exp_result;
 142
 143   json_element_object_begin (json_ctx);
 144   json_attr_uint (json_ctx, "length", (double)len);
 145   json_attr_uint (json_ctx, "align1", (double)align1);
 146   json_attr_uint (json_ctx, "align2", (double)align2);
 147   json_array_begin (json_ctx, "timings");
 148
 149   FOR_EACH_IMPL (impl, 0)
 150     do_one_test (json_ctx, impl, s1, s2, exp_result);
 151
 152   json_array_end (json_ctx);
 153   json_element_object_end (json_ctx);
 154 }
 155
 156 static void
 157 do_one_test_page_boundary (json_ctx_t *json_ctx, CHAR *s1, CHAR *s2,
 158                            size_t align1, size_t align2, size_t len,
 159                            int exp_result)
 160 {
 161   json_element_object_begin (json_ctx);
 162   json_attr_uint (json_ctx, "length", (double) len);
 163   json_attr_uint (json_ctx, "align1", (double) align1);
 164   json_attr_uint (json_ctx, "align2", (double) align2);
 165   json_array_begin (json_ctx, "timings");
 166   FOR_EACH_IMPL (impl, 0)
 167     do_one_test (json_ctx, impl, s1, s2, exp_result);
 168   json_array_end (json_ctx);
 169   json_element_object_end (json_ctx);
 170 }
 171
 172 static void
 173 do_test_page_boundary (json_ctx_t *json_ctx)
 174 {
 175   /* To trigger bug 25933, we need a size that is equal to the vector
 176      length times 4. In the case of AVX2 for Intel, we need 32 * 4.  We
 177      make this test generic and run it for all architectures as additional
 178      boundary testing for such related algorithms.  */
 179   size_t size = 32 * 4;
 180   size_t len;
 181   CHAR *s1 = (CHAR *) (buf1 + (BUF1PAGES - 1) * page_size);
 182   CHAR *s2 = (CHAR *) (buf2 + (BUF1PAGES - 1) * page_size);
 183   int exp_result;
 184
 185   memset (s1, 'a', page_size);
 186   memset (s2, 'a', page_size);
 187
 188   s1[(page_size / CHARBYTES) - 1] = (CHAR) 0;
 189   s2[(page_size / CHARBYTES) - 1] = (CHAR) 0;
 190
 191   /* Iterate over a size that is just below where we expect the bug to
 192      trigger up to the size we expect will trigger the bug e.g. [99-128].
 193      Likewise iterate the start of two strings between 30 and 31 bytes
 194      away from the boundary to simulate alignment changes.  */
 195   for (size_t s = 99; s <= size; s++)
 196     for (size_t s1a = 30; s1a < 32; s1a++)
 197       for (size_t s2a = 30; s2a < 32; s2a++)
 198         {
 199           size_t align1 = (page_size / CHARBYTES - s) - s1a;
 200           size_t align2 = (page_size / CHARBYTES - s) - s2a;
 201           CHAR *s1p = s1 + align1;
 202           CHAR *s2p = s2 + align2;
 203           len = (page_size / CHARBYTES) - 1 - align1;
 204           exp_result = SIMPLE_STRCMP (s1p, s2p);
 205           do_one_test_page_boundary (json_ctx, s1p, s2p, align1, align2,
 206                                      len, exp_result);
 207         }
 208 }
 209
 210 int
 211 test_main (void)
 212 {
 213   json_ctx_t json_ctx;
 214   size_t i, j, k;
 215   size_t pg_sz = getpagesize ();
 216
 217   test_init ();
 218
 219   json_init (&json_ctx, 0, stdout);
 220
 221   json_document_begin (&json_ctx);
 222   json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
 223
 224   json_attr_object_begin (&json_ctx, "functions");
 225   json_attr_object_begin (&json_ctx, TEST_NAME);
 226   json_attr_string (&json_ctx, "bench-variant", "default");
 227
 228   json_array_begin (&json_ctx, "ifuncs");
 229   FOR_EACH_IMPL (impl, 0)
 230     json_element_string (&json_ctx, impl->name);
 231   json_array_end (&json_ctx);
 232
 233   json_array_begin (&json_ctx, "results");
 234   for (k = 0; k < 2; ++k)
 235     {
 236       for (i = 1; i < 32; ++i)
 237         {
 238           do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 0, k);
 239           do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 1, k);
 240           do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, -1, k);
 241         }
 242
 243       for (i = 1; i <= 8192;)
 244         {
 245           /* No page crosses.  */
 246           do_test (&json_ctx, 0, 0, i, MIDCHAR, 0, k);
 247           do_test (&json_ctx, i * CHARBYTES, 0, i, MIDCHAR, 0, k);
 248           do_test (&json_ctx, 0, i * CHARBYTES, i, MIDCHAR, 0, k);
 249
 250           /* False page crosses.  */
 251           do_test (&json_ctx, pg_sz / 2, pg_sz / 2 - CHARBYTES, i, MIDCHAR, 0,
 252                    k);
 253           do_test (&json_ctx, pg_sz / 2 - CHARBYTES, pg_sz / 2, i, MIDCHAR, 0,
 254                    k);
 255
 256           do_test (&json_ctx, pg_sz - (i * CHARBYTES), 0, i, MIDCHAR, 0, k);
 257           do_test (&json_ctx, 0, pg_sz - (i * CHARBYTES), i, MIDCHAR, 0, k);
 258
 259           /* Real page cross.  */
 260           for (j = 16; j < 128; j += 16)
 261             {
 262               do_test (&json_ctx, pg_sz - j, 0, i, MIDCHAR, 0, k);
 263               do_test (&json_ctx, 0, pg_sz - j, i, MIDCHAR, 0, k);
 264
 265               do_test (&json_ctx, pg_sz - j, pg_sz - j / 2, i, MIDCHAR, 0, k);
 266               do_test (&json_ctx, pg_sz - j / 2, pg_sz - j, i, MIDCHAR, 0, k);
 267             }
 268
 269           if (i < 32)
 270             {
 271               ++i;
 272             }
 273           else if (i < 160)
 274             {
 275               i += 8;
 276             }
 277           else if (i < 512)
 278             {
 279               i += 32;
 280             }
 281           else
 282             {
 283               i *= 2;
 284             }
 285         }
 286
 287       for (i = 1; i < 10 + CHARBYTESLOG; ++i)
 288         {
 289           do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 0, k);
 290           do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 0, k);
 291           do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 1, k);
 292           do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 1, k);
 293           do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, -1, k);
 294           do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, -1, k);
 295           do_test (&json_ctx, 0, CHARBYTES * i, 2 << i, MIDCHAR, 1, k);
 296           do_test (&json_ctx, CHARBYTES * i, CHARBYTES * (i + 1), 2 << i,
 297                    LARGECHAR, 1, k);
 298         }
 299
 300       for (i = 1; i < 8; ++i)
 301         {
 302           do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i,
 303                    MIDCHAR, 0, k);
 304           do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i,
 305                    LARGECHAR, 0, k);
 306           do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i,
 307                    MIDCHAR, 1, k);
 308           do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i,
 309                    LARGECHAR, 1, k);
 310           do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i,
 311                    MIDCHAR, -1, k);
 312           do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i,
 313                    LARGECHAR, -1, k);
 314         }
 315     }
 316   do_test_page_boundary (&json_ctx);
 317
 318   json_array_end (&json_ctx);
 319   json_attr_object_end (&json_ctx);
 320   json_attr_object_end (&json_ctx);
 321   json_document_end (&json_ctx);
 322
 323   return ret;
 324 }
 325
 326 #include <support/test-driver.c>