Phase coupled code generation for DSPs using a genetic algorithm

The growing use of digital signal processors (DSPs) in embedded systems necessitates the use of optimizing compilers supporting special hardware features. Due to the irregular architectures present in today´s DSPs there is a need of compilers which are capable of performing a phase coupling of the highly interdependent code generation subtasks and a graph based code selection. In this paper we present a code generator which performs a graph based code selection and a complete phase coupling of code selection, instruction scheduling (including compaction) and register allocation. In addition, our code generator takes into account effects of the subsequent address code generation phase. In order to solve the phase coupling problem and to handle the problem complexity, our code generator is based on a genetic algorithm. Experimental results for several benchmarks and an MP3 application for two DSPs show the effectiveness and the retargetability of our approach. Using the presented techniques, the number of execution cycles is reduced by 51 % on average for the M3-DSP and by 38% on average for the ADSP2100 compared to standard techniques.