Re: [PATCH] Benchtests: Remove simple_str(n)cmp

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 08/03/23 07:41, Wilco Dijkstra via Libc-alpha wrote:
> 
> Instead of benchmarking slow byte oriented loops, include the optimized generic
> strcmp/strncmp implementation. Adjust iteration count to reduce benchmark time.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> 
> ---
> 
> diff --git a/benchtests/bench-strcmp.c b/benchtests/bench-strcmp.c
> index 8cd690bac1a612d99ecd11c8dc917f7cc36e19ea..65fd04b43a2aeaab85ee4996f083333a32d7b29f 100644
> --- a/benchtests/bench-strcmp.c
> +++ b/benchtests/bench-strcmp.c
> @@ -23,59 +23,26 @@
>  # define TEST_NAME "strcmp"
>  #endif
>  #include "bench-string.h"
> +#include "json-lib.h"
>  
>  #ifdef WIDE
> -# define L(str) L##str
> -# define SIMPLE_STRCMP simple_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;
> -}
> -
>  #else
> -# include <limits.h>
> -
> -# define L(str) str
> -# define SIMPLE_STRCMP simple_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;
> +generic_strcmp (const char *s1, const char *s2);
>  
> -  while ((ret = *(unsigned char *) s1 - *(unsigned char*) s2++) == 0 && *s1++);
> -  return ret;
> -}
> +IMPL (generic_strcmp, 0)
>  
>  #endif
>  
> -# include "json-lib.h"
> -
>  typedef int (*proto_t) (const CHAR *, const CHAR *);
>  
> -IMPL (SIMPLE_STRCMP, 1)
>  IMPL (STRCMP, 1)
>  
>  static void
> @@ -83,7 +50,7 @@ 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_ITERS8;
> +  size_t i, iters = INNER_LOOP_ITERS;
>    timing_t start, stop, cur;
>  
>    TIMING_NOW (start);
> @@ -201,7 +168,7 @@ do_test_page_boundary (json_ctx_t *json_ctx)
>  	  CHAR *s1p = s1 + align1;
>  	  CHAR *s2p = s2 + align2;
>  	  len = (page_size / CHARBYTES) - 1 - align1;
> -	  exp_result = SIMPLE_STRCMP (s1p, s2p);
> +	  exp_result = STRCMP (s1p, s2p);
>  	  do_one_test_page_boundary (json_ctx, s1p, s2p, align1, align2,
>  				     len, exp_result);
>  	}
> @@ -324,3 +291,9 @@ test_main (void)
>  }
>  
>  #include <support/test-driver.c>
> +
> +#ifndef WIDE
> +# undef STRCMP
> +# define STRCMP generic_strcmp
> +# include <string/strcmp.c>
> +#endif
> diff --git a/benchtests/bench-strncmp.c b/benchtests/bench-strncmp.c
> index a714e5a9d42541f8781c3e92f0212cb9ab18e61f..53707e6bca675efe57a16cce3c343153a18894ab 100644
> --- a/benchtests/bench-strncmp.c
> +++ b/benchtests/bench-strncmp.c
> @@ -21,61 +21,31 @@
>  # define TEST_NAME "wcsncmp"
>  #else
>  # define TEST_NAME "strncmp"
> -#endif /* !WIDE */
> +#endif
>  #include "bench-string.h"
>  #include "json-lib.h"
>  
>  #ifdef WIDE
> -# define L(str) L##str
>  # define STRDUP wcsdup
> -# define SIMPLE_STRNCMP simple_wcsncmp
> -
> -/* Wcsncmp uses signed semantics for comparison, not unsigned.
> -   Avoid using substraction since possible overflow.  */
> -int
> -simple_wcsncmp (const CHAR *s1, const CHAR *s2, size_t n)
> -{
> -  wchar_t c1, c2;
> -
> -  while (n--)
> -    {
> -      c1 = *s1++;
> -      c2 = *s2++;
> -      if (c1 == L ('\0') || c1 != c2)
> -	return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
> -    }
> -  return 0;
> -}
> -
>  #else
> -# define L(str) str
>  # define STRDUP strdup
> -# define SIMPLE_STRNCMP simple_strncmp
>  
> -/* Strncmp uses unsigned semantics for comparison.  */
>  int
> -simple_strncmp (const char *s1, const char *s2, size_t n)
> -{
> -  int ret = 0;
> +generic_strncmp (const char *s1, const char *s2, size_t n);
>  
> -  while (n-- && (ret = *(unsigned char *) s1 - * (unsigned char *) s2++) == 0
> -	 && *s1++);
> -  return ret;
> -}
> +IMPL (generic_strncmp, 0)
>  
> -#endif /* !WIDE */
> +#endif
>  
>  typedef int (*proto_t) (const CHAR *, const CHAR *, size_t);
>  
> -IMPL (SIMPLE_STRNCMP, 0)
>  IMPL (STRNCMP, 1)
>  
> -
>  static void
>  do_one_test (json_ctx_t *json_ctx, impl_t *impl, const CHAR *s1, const CHAR
>  	     *s2, size_t n, int exp_result)
>  {
> -  size_t i, iters = INNER_LOOP_ITERS8;
> +  size_t i, iters = INNER_LOOP_ITERS;
>    timing_t start, stop, cur;
>  
>    TIMING_NOW (start);
> @@ -240,7 +210,7 @@ do_test_page_boundary (json_ctx_t *json_ctx)
>  	  CHAR *s1p = s1 + align1;
>  	  CHAR *s2p = s2 + align2;
>  	  len = (page_size / CHARBYTES) - 1 - align1;
> -	  exp_result = SIMPLE_STRNCMP (s1p, s2p, s);
> +	  exp_result = STRNCMP (s1p, s2p, s);
>  	  do_one_test_page_boundary (json_ctx, s1p, s2p, align1, align2,
>  				     len, s, exp_result);
>  	}
> @@ -456,3 +426,10 @@ test_main (void)
>  }
>  
>  #include <support/test-driver.c>
> +
> +#ifndef WIDE
> +# undef STRNCMP
> +# define STRNCMP generic_strncmp
> +# define libc_hidden_builtin_def(X)
> +# include <string/strncmp.c>
> +#endif
>