This is the mail archive of the libc-alpha@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] Improve memccpy performance


On Wed, Apr 15, 2015 at 01:31:30PM +0100, Wilco Dijkstra wrote:
> ping
> 
> > Wilco Dijkstra wrote: 
> > > Wilco Dijkstra wrote:
> > > > Richard Earnshaw wrote:
> > > > On 14/01/15 18:14, Roland McGrath wrote:
> > > > >> +      return memcpy (dest, src, n) + n;
> > > > >
> > > > > Use __mempcpy here.
> > > > >
> > > > That will be worse if mempcpy just calls memcpy; which is what the C
> > > > library implementation does.
> > >
> > > If GLIBC inlines mempcpy like I proposed then it would be reasonable
> > > to use mempcpy here as it results in exactly the same code.
> > 
> > So, OK for trunk with __mempcpy like below?
> > 
> > ---
> >  string/memccpy.c | 14 +++++++-------
> >  1 file changed, 7 insertions(+), 7 deletions(-)
> > 
> > diff --git a/string/memccpy.c b/string/memccpy.c
> > index 70ee2ae..d4146f9 100644
> > --- a/string/memccpy.c
> > +++ b/string/memccpy.c
> > @@ -26,15 +26,15 @@
> >  void *
> >  __memccpy (void *dest, const void *src, int c, size_t n)
> >  {
> > -  const char *s = src;
> > -  char *d = dest;
> > -  const char x = c;
> > -  size_t i = n;
> > +  void *p = memchr (src, c, n);
> > 
> > -  while (i-- > 0)
> > -    if ((*d++ = *s++) == x)
> > -      return d;
> > +  if (p != NULL)
> > +    {
> > +      n = p - src + 1;
> > +      return __mempcpy (dest, src, n);
> > +    }
> > 
> > +  memcpy (dest, src, n);
> >    return NULL;
> >  }
> > 
> > --
> > 1.9.1

ok for me. 


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]