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RE: [PATCH] Improve performance of strncat


> Adhemerval Zanella wrote:
>From what is worth, this is similar optimization I pushed for powerpc
>(which some more arch-specific tunings) and looks ok.
>
>PS: try to send patch as inline instead of attachments.

I can for small changes but due to Outlook there will always be some bad 
characters in it...

I assume this is OK for commit now the code freeze is over, unless there
are further comments in 48 hours.

Wilco

On 20-08-2014 09:44, Wilco Dijkstra wrote:
> Hi,
>
> This patch improves strncat performance by using strlen. Strlen has a fast C implementation, so
this
> will improve performance even on targets which don't have an optimized strlen. It is about twice
as
> fast as the original strncat in bench-strncat.
>
> ChangeLog:
> 2014-08-20  Wilco Dijkstra  <wdijkstr@arm.com>
>
> 	* string/strncat.c (strncat): Improve performance by using strlen.
> ---
>  string/strncat.c |    6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/string/strncat.c b/string/strncat.c
> index 7ac4456..6d29114 100644
> --- a/string/strncat.c
> +++ b
> @@ -33,13 +33,11 @@ STRNCAT (char *s1, const char *s2, size_t n)
>    char *s = s1;
>  
>    /* Find the end of S1.  */
> -  do
> -    c = *s1++;
> -  while (c != '\0');
> +  s1 += strlen (s1);
>  
>    /* Make S1 point before next character, so we can increment
>       it while memory is read (wins on pipelined cpus).  */
> -  s1 -= 2;
> +  s1 -= 1;
>  
>    if (n >= 4)
>      {
> -- 1.7.9.5





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