Integer Linear Programming versus Dynamic Programming for Optimal Integrated VLIW Code Generation

To our knowledge there is only one Integer Linear Program ming ILP formulation in the literature that fully integrates all steps of code generation i e instruction selection register allocation and in struction scheduling on the basic block level We give in this paper an improved version of this ILP formulation that also covers VLIW proces sors Moreover our ILP formulation does no longer require preprocessing the basic block s data ow graph to support instruction selection In earlier work we proposed and implemented a dynamic programming DP based method for optimal integrated code generation called OP TIMIST In this paper we give rst results to evaluate and compare our ILP formulation with our DP method on a VLIW processor We identify di erent code situations and shapes of data dependence graphs for which either ILP or DP is most suitable