[PATCH] Inline mempcpy

[Wilco Dijkstra]

> Ondřej Bílka wrote:
> On Wed, May 20, 2015 at 12:53:24PM +0100, Wilco Dijkstra wrote:
> > > Joseph Myers wrote:
> > > On Mon, 18 May 2015, Wilco Dijkstra wrote:
> > >
> > > This seems plausible, subject to getting per-architecture agreement (for
> > > each architecture with mempcpy.S) on whether to define
> > > _HAVE_STRING_ARCH_mempcpy.  Although there may be the question of whether
> > > __extern_always_inline should be defined at all for !__GNUC_PREREQ (3,2)
> > > (i.e. when the always_inline attribute isn't supported).
> >
> > It would be good to fix the *always_inline defines, but I for now I've added
> > an extra check for __GNUC_PREREQ (3,2) to be sure we don't fail to inline on
> > really old GCCs. So here's the actual patch - I've disabled inlining for SPARC,
> > and from previous comments it seems people prefer the inline mempcpy on x64/x86
> > and PPC (I've included the maintainers for those arches to agree/veto).
> >
> > OK for commit?
> >
> > Wilco
> >
> Adhemerval already acked this for powerpc in this thread.
> For x64 I obviously agree. I added optimized memcpy. As mempcpy I
> submitted patch, then forgotten about it after about ten pings.

Yes it people generally agree this is the right thing to do but I still
need to get agreement from the arch maintainers for this specific patch.

> So on x64 on sandy bridge this will improve performance by around 50% on
> larger strings as you see even in benchtest

Are you talking about your new memcpy here or the mempcpy patch? I don't think 
My patch will affect performance simplistic tests - it reduces I-cache/BP 
pressure which is not what benchtest tries to measure.

Wilco