Re: [PATCH v1 1/3] string: Add len=0 to {w}memcmp{eq} tests and benchtests

[Siddhesh Poyarekar <siddhesh@gotplt.org>]

LGTM.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

On 2022-10-29 16:19, Noah Goldstein via Libc-alpha wrote:
> len=0 is valid and fairly common so should be tested.
> ---
>   benchtests/bench-memcmp.c | 18 +++++++++---------
>   string/test-memcmp.c      | 16 ++++++++++------
>   2 files changed, 19 insertions(+), 15 deletions(-)
> 
> diff --git a/benchtests/bench-memcmp.c b/benchtests/bench-memcmp.c
> index d64eaa992e..b2816baebe 100644
> --- a/benchtests/bench-memcmp.c
> +++ b/benchtests/bench-memcmp.c
> @@ -63,7 +63,7 @@ IMPL (MEMCMP, 1)
>   
>   static void
>   do_one_test (json_ctx_t *json_ctx, impl_t *impl, const CHAR *s1,
> -	     const CHAR *s2, size_t len, int exp_result)
> +	     const CHAR *s2, size_t len)
>   {
>     size_t i, iters = INNER_LOOP_ITERS_LARGE;
>     timing_t start, stop, cur;
> @@ -87,9 +87,6 @@ do_test (json_ctx_t *json_ctx, size_t align1, size_t align2, size_t len,
>     size_t i;
>     CHAR *s1, *s2;
>   
> -  if (len == 0)
> -    return;
> -
>     align1 &= (4096 - CHARBYTES);
>     if (align1 + (len + 1) * CHARBYTES >= page_size)
>       return;
> @@ -111,13 +108,16 @@ do_test (json_ctx_t *json_ctx, size_t align1, size_t align2, size_t len,
>     for (i = 0; i < len; i++)
>       s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % MAX_CHAR;
>   
> -  s1[len] = align1;
> -  s2[len] = align2;
> -  s2[len - 1] -= exp_result;
> +  if (len)
> +    {
> +      s1[len] = align1;
> +      s2[len] = align2;
> +      s2[len - 1] -= exp_result;
> +    }
>   
>     FOR_EACH_IMPL (impl, 0)
>       {
> -      do_one_test (json_ctx, impl, s1, s2, len, exp_result);
> +      do_one_test (json_ctx, impl, s1, s2, len);
>       }
>   
>     json_array_end (json_ctx);
> @@ -147,7 +147,7 @@ test_main (void)
>     json_array_end (&json_ctx);
>   
>     json_array_begin (&json_ctx, "results");
> -  for (i = 1; i < 32; ++i)
> +  for (i = 0; i < 32; ++i)
>       {
>         do_test (&json_ctx, i * CHARBYTES, i * CHARBYTES, i, 0);
>         do_test (&json_ctx, i * CHARBYTES, i * CHARBYTES, i, 1);
> diff --git a/string/test-memcmp.c b/string/test-memcmp.c
> index 181b689f68..18d8b0d9f1 100644
> --- a/string/test-memcmp.c
> +++ b/string/test-memcmp.c
> @@ -117,9 +117,6 @@ do_test (size_t align1, size_t align2, size_t len, int exp_result)
>     size_t i;
>     CHAR *s1, *s2;
>   
> -  if (len == 0)
> -    return;
> -
>     align1 &= (4096 - CHARBYTES);
>     if (align1 + (len + 1) * CHARBYTES >= page_size)
>       return;
> @@ -134,9 +131,16 @@ do_test (size_t align1, size_t align2, size_t len, int exp_result)
>     for (i = 0; i < len; i++)
>       s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % CHAR__MAX;
>   
> -  s1[len] = align1;
> -  s2[len] = align2;
> -  s2[len - 1] -= exp_result;
> +  if (len)
> +    {
> +      s1[len] = align1;
> +      s2[len] = align2;
> +      s2[len - 1] -= exp_result;
> +    }
> +  else
> +    {
> +      exp_result = 0;
> +    }
>   
>     FOR_EACH_IMPL (impl, 0)
>       do_one_test (impl, s1, s2, len, exp_result);