glibc/benchtests/bench-strncmp.c

/* Measure strncmp functions.
   Copyright (C) 2013-2015 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
#define TEST_NAME "strncmp"
#include "bench-string.h"

typedef int (*proto_t) (const char *, const char *, size_t);
int simple_strncmp (const char *, const char *, size_t);
int stupid_strncmp (const char *, const char *, size_t);

IMPL (stupid_strncmp, 0)
IMPL (simple_strncmp, 0)
IMPL (strncmp, 1)

int
simple_strncmp (const char *s1, const char *s2, size_t n)
{
  int ret = 0;

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

int
stupid_strncmp (const char *s1, const char *s2, size_t n)
{
  size_t ns1 = strnlen (s1, n) + 1, ns2 = strnlen (s2, n) + 1;
  int ret = 0;

  n = ns1 < n ? ns1 : n;
  n = ns2 < n ? ns2 : n;
  while (n-- && (ret = *(unsigned char *) s1++ - * (unsigned char *) s2++) == 0);
  return ret;
}

static void
do_one_test (impl_t *impl, const char *s1, const char *s2, size_t n,
	     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, n);
    }
  TIMING_NOW (stop);

  TIMING_DIFF (cur, start, stop);

  TIMING_PRINT_MEAN ((double) cur, (double) iters);
}

static void
do_test_limit (size_t align1, size_t align2, size_t len, size_t n, int max_char,
	 int exp_result)
{
  size_t i, align_n;
  char *s1, *s2;

  if (n == 0)
    {
      s1 = (char*)(buf1 + page_size);
      s2 = (char*)(buf2 + page_size);
      printf ("Length %4zd/%4zd:", len, n);

      FOR_EACH_IMPL (impl, 0)
	do_one_test (impl, s1, s2, n, 0);

      putchar ('\n');

      return;
    }

  align1 &= 15;
  align2 &= 15;
  align_n = (page_size - n) & 15;

  s1 = (char*)(buf1 + page_size - n);
  s2 = (char*)(buf2 + page_size - n);

  if (align1 < align_n)
    s1 -= (align_n - align1);

  if (align2 < align_n)
    s2 -= (align_n - align2);

  for (i = 0; i < n; i++)
    s1[i] = s2[i] = 1 + 23 * i % max_char;

  if (len < n)
    {
      s1[len] = 0;
      s2[len] = 0;
      if (exp_result < 0)
	s2[len] = 32;
      else if (exp_result > 0)
	s1[len] = 64;
    }

  printf ("Length %4zd/%4zd, alignment %2zd/%2zd:", len, n, align1, align2);

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

  putchar ('\n');
}

static void
do_test (size_t align1, size_t align2, size_t len, size_t n, int max_char,
	 int exp_result)
{
  size_t i;
  char *s1, *s2;

  if (n == 0)
    return;

  align1 &= 7;
  if (align1 + n + 1 >= page_size)
    return;

  align2 &= 7;
  if (align2 + n + 1 >= page_size)
    return;

  s1 = (char*)(buf1 + align1);
  s2 = (char*)(buf2 + align2);

  for (i = 0; i < n; i++)
    s1[i] = s2[i] = 1 + 23 * i % max_char;

  s1[n] = 24 + exp_result;
  s2[n] = 23;
  s1[len] = 0;
  s2[len] = 0;
  if (exp_result < 0)
    s2[len] = 32;
  else if (exp_result > 0)
    s1[len] = 64;
  if (len >= n)
    s2[n - 1] -= exp_result;

  printf ("Length %4zd/%4zd, alignment %2zd/%2zd:", len, n, align1, align2);

  FOR_EACH_IMPL (impl, 0)
    do_one_test (impl, (char*)s1, (char*)s2, n, exp_result);

  putchar ('\n');
}

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 < 16; ++i)
    {
      do_test (0, 0, 8, i, 127, 0);
      do_test (0, 0, 8, i, 127, -1);
      do_test (0, 0, 8, i, 127, 1);
      do_test (i, i, 8, i, 127, 0);
      do_test (i, i, 8, i, 127, 1);
      do_test (i, i, 8, i, 127, -1);
      do_test (i, 2 * i, 8, i, 127, 0);
      do_test (2 * i, i, 8, i, 127, 1);
      do_test (i, 3 * i, 8, i, 127, -1);
      do_test (0, 0, 8, i, 255, 0);
      do_test (0, 0, 8, i, 255, -1);
      do_test (0, 0, 8, i, 255, 1);
      do_test (i, i, 8, i, 255, 0);
      do_test (i, i, 8, i, 255, 1);
      do_test (i, i, 8, i, 255, -1);
      do_test (i, 2 * i, 8, i, 255, 0);
      do_test (2 * i, i, 8, i, 255, 1);
      do_test (i, 3 * i, 8, i, 255, -1);
    }

  for (i = 1; i < 8; ++i)
    {
      do_test (0, 0, 8 << i, 16 << i, 127, 0);
      do_test (0, 0, 8 << i, 16 << i, 127, 1);
      do_test (0, 0, 8 << i, 16 << i, 127, -1);
      do_test (0, 0, 8 << i, 16 << i, 255, 0);
      do_test (0, 0, 8 << i, 16 << i, 255, 1);
      do_test (0, 0, 8 << i, 16 << i, 255, -1);
      do_test (8 - i, 2 * i, 8 << i, 16 << i, 127, 0);
      do_test (8 - i, 2 * i, 8 << i, 16 << i, 127, 1);
      do_test (2 * i, i, 8 << i, 16 << i, 255, 0);
      do_test (2 * i, i, 8 << i, 16 << i, 255, 1);
    }

  do_test_limit (0, 0, 0, 0, 127, 0);
  do_test_limit (4, 0, 21, 20, 127, 0);
  do_test_limit (0, 4, 21, 20, 127, 0);
  do_test_limit (8, 0, 25, 24, 127, 0);
  do_test_limit (0, 8, 25, 24, 127, 0);

  for (i = 0; i < 8; ++i)
    {
      do_test_limit (0, 0, 17 - i, 16 - i, 127, 0);
      do_test_limit (0, 0, 17 - i, 16 - i, 255, 0);
      do_test_limit (0, 0, 15 - i, 16 - i, 127, 0);
      do_test_limit (0, 0, 15 - i, 16 - i, 127, 1);
      do_test_limit (0, 0, 15 - i, 16 - i, 127, -1);
      do_test_limit (0, 0, 15 - i, 16 - i, 255, 0);
      do_test_limit (0, 0, 15 - i, 16 - i, 255, 1);
      do_test_limit (0, 0, 15 - i, 16 - i, 255, -1);
    }

  return ret;
}

#include "../test-skeleton.c"