%T Auto\-Mobiles: Optimised Message\-Passing
%A  Neil C.C. Brown
%E Peter H. Welch,  Herman Roebbers,  Jan F. Broenink,  Frederick R. M. Barnes,  Carl G. Ritson,  Adam T. Sampson,  G. S. Stiles,  Brian Vinter
%B Communicating Process Architectures 2009
%X Some message\-passing concurrent systems, such as occam 2,
   prohibit
aliasing of data objects.  Communicated data must
   thus be copied,
which can be time\-intensive for large data
   packets such as video
frames.  We introduce automatic
   mobility, a compiler optimisation that
performs
   communications by reference and deduces when
   these
communications can be performed without copying.  We
   discuss bounds
for speed\-up and memory use, and benchmark
   the automatic mobility
optimisation.  We show that in the
   best case it can transform an
operation from being linear
   with respect to packet size into
constant\-time.