Register saturation (RS) is the exact maximal register need of all
valid schedules of a data dependence graph. Its optimal computation is
NP-complete. This report proposes two variants of heuristics for
computing the acyclic RS of directed acyclic graphs (DAG of basic
blocks and super-blocks). The first one improves the previous greedy-k
heuristic in terms of approximating the RS with equivalent computation
times. The second heuristic is faster, has better RS approximation
than greedy-k, but scarifies the computation of saturating values.
Our RS computation methods are distributed as a C independent library
(RSlib) under LGPL licence.
Working software (free sources), experimental data and full report
available here:
http://hal.archives-ouvertes.fr/inria-00431103/