  The rapidly increasing number of cores available in multicore processors does
not necessarily lead directly to a commensurate increase in performance:
programs written in conventional languages, such as C, need careful
restructuring, preferably automatically, before the benefits can be observed in
improved run-times. Even then, much depends upon the intrinsic capacity of the
original program for concurrent execution. The subject of this paper is the
performance gains from the combined effect of the complementary techniques of
the Decoupled Software Pipeline (DSWP) and (backward) slicing. DSWP extracts
threadlevel parallelism from the body of a loop by breaking it into stages
which are then executed pipeline style: in effect cutting across the control
chain. Slicing, on the other hand, cuts the program along the control chain,
teasing out finer threads that depend on different variables (or locations).
parts that depend on different variables. The main contribution of this paper
is to demonstrate that the application of DSWP, followed by slicing offers
notable improvements over DSWP alone, especially when there is a loop-carried
dependence that prevents the application of the simpler DOALL optimization.
Experimental results show an improvement of a factor of ?1.6 for DSWP + slicing
over DSWP alone and a factor of ?2.4 for DSWP + slicing over the original
sequential code.
