% $Id: concl.tex,v 1.7 1997/07/30 17:52:39 cierniak Exp $

\section{CONCLUSION}
\label{sec:concl}

We have implemented a very fast algorithm to decide and perform an
optimizing transformation which can significantly speedup execution
times of many scientific benchmarks.  Currently the speedups are
between 10\% and 20\%, but when Kaffe, the JIT compiler used by us,
will perform standard optimizations which are absent in its current
version, the speedups should be similar to the ones observed for
Fortran programs---up to 50\%.

Our previous experience with an off-line Java optimizer has shown that
some traditional algorithms used in compilers are too slow for a JIT
compiler.  We have proposed and implemented faster ways of performing
analyses needed for our optimizations.  For instance we have replaced
the {\em reaching definition\/} with {\em constant values\/} and {\em
  loop induction variables\/} with {\em loop-defined variables}.  As
the result our JIT compiler is extremely fast, so that its running
time is negligible even when the data sets used with our benchmarks
result in execution times of only a few seconds.  The impact for the
same benchmarks running on more realistic problem sizes would be even
smaller.

