glibc/benchtests/bench-strcmp.c

/* Measure strcmp and wcscmp 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
   <http://www.gnu.org/licenses/>.  */

#define TEST_MAIN
#ifdef WIDE
# define TEST_NAME "wcscmp"
#else
# define TEST_NAME "strcmp"
#endif
#include "bench-string.h"

#ifdef WIDE
# define L(str) L##str
# define SIMPLE_STRCMP simple_wcscmp
# define STUPID_STRCMP stupid_wcscmp
# define CHARBYTESLOG 2
# define MIDCHAR 0x7fffffff
# define LARGECHAR 0xfffffffe

/* Wcscmp uses signed semantics for comparison, not unsigned */
/* Avoid using substraction since possible overflow */

int
simple_wcscmp (const wchar_t *s1, const wchar_t *s2)
{
  wchar_t c1, c2;
  do
    {
      c1 = *s1++;
      c2 = *s2++;
      if (c2 == L'\0')
      return c1 - c2;
    }
  while (c1 == c2);

  return c1 < c2 ? -1 : 1;
}

int
stupid_wcscmp (const wchar_t *s1, const wchar_t *s2)
{
  size_t ns1 = wcslen (s1) + 1;
  size_t ns2 = wcslen (s2) + 1;
  size_t n = ns1 < ns2 ? ns1 : ns2;
  int ret = 0;

  wchar_t c1, c2;

  while (n--) {
    c1 = *s1++;
    c2 = *s2++;
    if ((ret = c1 < c2 ? -1 : c1 == c2 ? 0 : 1) != 0)
      break;
  }
  return ret;
}

#else
# include <limits.h>

# define L(str) str
# define SIMPLE_STRCMP simple_strcmp
# define STUPID_STRCMP stupid_strcmp
# define CHARBYTESLOG 0
# define MIDCHAR 0x7f
# define LARGECHAR 0xfe

/* Strcmp uses unsigned semantics for comparison. */
int
simple_strcmp (const char *s1, const char *s2)
{
  int ret;

  while ((ret = *(unsigned char *) s1 - *(unsigned char*) s2++) == 0 && *s1++);
  return ret;
}

int
stupid_strcmp (const char *s1, const char *s2)
{
  size_t ns1 = strlen (s1) + 1;
  size_t ns2 = strlen (s2) + 1;
  size_t n = ns1 < ns2 ? ns1 : ns2;
  int ret = 0;

  while (n--)
    if ((ret = *(unsigned char *) s1++ - *(unsigned char *) s2++) != 0)
      break;
  return ret;
}
#endif

# include "json-lib.h"

typedef int (*proto_t) (const CHAR *, const CHAR *);

IMPL (STUPID_STRCMP, 1)
IMPL (SIMPLE_STRCMP, 1)
IMPL (STRCMP, 1)

static void
do_one_test (json_ctx_t *json_ctx, impl_t *impl,
	     const CHAR *s1, const CHAR *s2,
	     int exp_result)
{
  size_t i, iters = INNER_LOOP_ITERS;
  timing_t start, stop, cur;

  TIMING_NOW (start);
  for (i = 0; i < iters; ++i)
    {
      CALL (impl, s1, s2);
    }
  TIMING_NOW (stop);

  TIMING_DIFF (cur, start, stop);

  json_element_double (json_ctx, (double) cur / (double) iters);
}

static void
do_test (json_ctx_t *json_ctx, size_t align1, size_t align2, size_t len, int
	 max_char, int exp_result)
{
  size_t i;

  CHAR *s1, *s2;

  if (len == 0)
    return;

  align1 &= 63;
  if (align1 + (len + 1) * CHARBYTES >= page_size)
    return;

  align2 &= 63;
  if (align2 + (len + 1) * CHARBYTES >= page_size)
    return;

  /* Put them close to the end of page.  */
  i = align1 + CHARBYTES * (len + 2);
  s1 = (CHAR *) (buf1 + ((page_size - i) / 16 * 16) + align1);
  i = align2 + CHARBYTES * (len + 2);
  s2 = (CHAR *) (buf2 + ((page_size - i) / 16 * 16)  + align2);

  for (i = 0; i < len; i++)
    s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % max_char;

  s1[len] = s2[len] = 0;
  s1[len + 1] = 23;
  s2[len + 1] = 24 + exp_result;
  s2[len - 1] -= exp_result;

  json_element_object_begin (json_ctx);
  json_attr_uint (json_ctx, "length", (double) len);
  json_attr_uint (json_ctx, "align1", (double) align1);
  json_attr_uint (json_ctx, "align2", (double) align2);
  json_array_begin (json_ctx, "timings");

  FOR_EACH_IMPL (impl, 0)
    do_one_test (json_ctx, impl, s1, s2, exp_result);

  json_array_end (json_ctx);
  json_element_object_end (json_ctx);
}

int
test_main (void)
{
  json_ctx_t json_ctx;
  size_t i;

  test_init ();

  json_init (&json_ctx, 0, stdout);

  json_document_begin (&json_ctx);
  json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);

  json_attr_object_begin (&json_ctx, "functions");
  json_attr_object_begin (&json_ctx, TEST_NAME);
  json_attr_string (&json_ctx, "bench-variant", "default");

  json_array_begin (&json_ctx, "ifuncs");
  FOR_EACH_IMPL (impl, 0)
    json_element_string (&json_ctx, impl->name);
  json_array_end (&json_ctx);

  json_array_begin (&json_ctx, "results");

  for (i = 1; i < 32; ++i)
    {
      do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 0);
      do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 1);
      do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, -1);
    }

  for (i = 1; i < 10 + CHARBYTESLOG; ++i)
    {
      do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 0);
      do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 0);
      do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 1);
      do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 1);
      do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, -1);
      do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, -1);
      do_test (&json_ctx, 0, CHARBYTES * i, 2 << i, MIDCHAR, 1);
      do_test (&json_ctx, CHARBYTES * i, CHARBYTES * (i + 1), 2 << i, LARGECHAR, 1);
    }

  for (i = 1; i < 8; ++i)
    {
      do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i, MIDCHAR, 0);
      do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, 0);
      do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i, MIDCHAR, 1);
      do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, 1);
      do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i, MIDCHAR, -1);
      do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, -1);
    }

  json_array_end (&json_ctx);
  json_attr_object_end (&json_ctx);
  json_attr_object_end (&json_ctx);
  json_document_end (&json_ctx);

  return ret;
}

#include <support/test-driver.c>