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Re: [PATCH] Optimize strchr (s, 0) to strlen
On Thu, Sep 15, 2016 at 02:55:48PM +0000, Wilco Dijkstra wrote:
> Jakub Jelinek wrote:
> On Thu, Sep 15, 2016 at 03:16:52PM +0100, Szabolcs Nagy wrote:
> > >
> > > from libc point of view, rawmemchr is a rarely used
> > > nonstandard function that should be optimized for size.
> > > (glibc does not do this now, but it should in my opinion.)
> >
> > rawmemchr with 0 is to strlen conceptually like stpcpy is to strcpy.
> > Are you arguing that glibc should implement strcpy using stpcpy, or vice
> > versa?
>
> stpcpy is not conceptually the same, but for mempcpy, yes. By default
> it's converted into memcpy in the GLIBC headers and the generic implementation.
>
> stpcpy uses strlen and memcpy which is generally the most efficient version
> (it even beat several assembler implementations).
?? I certainly see something completely different, at least on the arches
I've looked at.
Jakub