[PATCH v4] string: Adds tests for test-strncasecmp and test-strncpy

Paul A. Clarke pc@us.ibm.com
Thu Jun 11 16:33:36 GMT 2020


On Wed, Jun 10, 2020 at 03:55:18PM -0300, Raphael Moreira Zinsly via Libc-alpha wrote:
> A couple more changes based on Adhemerval's review, thanks.
> 
> Changes since v3:
> 	- Using a cache line size of 64 if the system doesn't have meaningful
> 	information on _SC_LEVEL1_DCACHE_LINESIZE.
> 	- Using buf2 instead of a buf1 copy for s2 at
> 	string/test-strncasecmp.c.
> 
> --- >8 ---
> 
> Adds tests to check if strings placed at page bondaries are
> handled correctly by strncasecmp and strncpy similar to tests
> for strncmp and strnlen.
> ---
>  string/test-strncasecmp.c | 43 +++++++++++++++++++++++++++++++++++++++
>  string/test-strncpy.c     | 41 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 84 insertions(+)
> 
> diff --git a/string/test-strncasecmp.c b/string/test-strncasecmp.c
> index 6a9c27beae..63f6d59ef2 100644
> --- a/string/test-strncasecmp.c
> +++ b/string/test-strncasecmp.c
> @@ -137,6 +137,48 @@ do_test (size_t align1, size_t align2, size_t n, size_t len, int max_char,
>      do_one_test (impl, s1, s2, n, exp_result);
>  }
> 
> +static void
> +do_page_tests (void)
> +{
> +  size_t i, offset, cacheline_size;
> +  char *s1, *s2;
> +  int exp_result;
> +
> +  offset = page_size - 1;
> +  s1 = (char *) buf1;
> +  s2 = (char *) buf2;
> +  memset (s1, '\1', offset);
> +  memset (s2, '\1', offset);
> +  s1[offset] = '\0';
> +  s2[offset] = '\0';
> +
> +  /* s2 has a fixed offset, half page long.
> +     page_size is actually 2 * getpagesize.  */
> +  offset = page_size / 4;
> +  s2 += offset;
> +  /* Start offset for s1 at half of the second page.  */
> +  offset = 3 * page_size / 4;
> +  s1 += offset;
> +
> +  /* Try to cross the page boundary at every offset of a cache line.  */
> +  cacheline_size = sysconf (_SC_LEVEL1_DCACHE_LINESIZE);
> +  /* Use 64 as default.  */
> +  if(cacheline_size == 0)
> +    cacheline_size = 64;

A little bikeshedding here, but why not pick the largest common cache line
size, which would obvioulsy be a superset of all the rest?  Say, 128?

Also, the comment is probably not needed.  Indeed, you could coalesce:
  if ((cacheline_size = sysconf (_SC_LEVEL1_DCACHE_LINESIZE)) == 0)
    cacheline_size = 128;

> +  for (i = 0; i < cacheline_size; ++i)
> +    {
> +      exp_result = *s1;
> +
> +      FOR_EACH_IMPL (impl, 0)
> +	{
> +	  check_result (impl, s1, s2, page_size, -exp_result);
> +	  check_result (impl, s2, s1, page_size, exp_result);
> +	}
> +
> +      s1++;
> +    }
> +}
> +
>  static void
>  do_random_tests (void)
>  {
> @@ -334,6 +376,7 @@ test_locale (const char *locale)
>      }
> 
>    do_random_tests ();
> +  do_page_tests ();
>  }
> 
>  int
> diff --git a/string/test-strncpy.c b/string/test-strncpy.c
> index c978753ad8..051257f200 100644
> --- a/string/test-strncpy.c
> +++ b/string/test-strncpy.c
> @@ -155,6 +155,46 @@ do_test (size_t align1, size_t align2, size_t len, size_t n, int max_char)
>      do_one_test (impl, s2, s1, len, n);
>  }
> 
> +static void
> +do_page_tests (void)
> +{
> +  size_t i, small_len, big_len, short_offset, long_offset, cacheline_size;
> +  CHAR *s1, *s2;
> +  /* Calculate the null character offset.  */
> +  size_t last_offset = (page_size / sizeof (CHAR)) - 1;
> +
> +  s2 = (CHAR *) buf1;
> +  s1 = (CHAR *) buf2;
> +  MEMSET (s1, '\1', last_offset);
> +  s1[last_offset] = '\0';
> +
> +  long_offset = (last_offset + 1) / 2;
> +  short_offset = last_offset;
> +
> +  /* Try to cross the page boundary at every offset of a cache line.  */
> +  cacheline_size = sysconf (_SC_LEVEL1_DCACHE_LINESIZE);
> +  /* Use 64 as default.  */
> +  if(cacheline_size == 0)
> +    cacheline_size = 64;

same.

> +  for (i = 0; i < cacheline_size; i++)
> +    {
> +      /* Place long strings ending at page boundary.  */
> +      long_offset++;
> +      big_len = last_offset - long_offset;
> +      /* Place short strings ending at page boundary.  */
> +      short_offset--;
> +      small_len = last_offset - short_offset;
> +
> +      FOR_EACH_IMPL (impl, 0)
> +        {
> +	  do_one_test (impl, s2, (CHAR *) (s1 + short_offset), small_len,
> +	               small_len);
> +	  do_one_test (impl, s2, (CHAR *) (s1 + long_offset), page_size,
> +	               big_len);
> +	}
> +    }
> +}
> +
>  static void
>  do_random_tests (void)
>  {
> @@ -317,6 +357,7 @@ test_main (void)
>      }
> 
>    do_random_tests ();
> +  do_page_tests ();
>    return ret;
>  }
> 

LGTM with above nits addressed.

PC


More information about the Libc-alpha mailing list