A Sound and Complete Algorithm for Code Generation in Distance-Based ISA

Abstract

The single-thread performance of a processor core is essential even in the multicore era. However, increasing the processing width of a core to improve the single-thread performance leads to a super-linear increase in power consumption. To overcome this power consumption issue, an instruction set architecture for general-purpose processors, called STRAIGHT, has been proposed. STRAIGHT adopts a distance-based ISA, in which source operands are specified by the distance between instructions. In STRAIGHT, it is necessary to satisfy constraints on the distance used as operands to generate executable code. However, it is not yet clear how to generate code that satisfies these constraints in the general case. In this paper, we propose three compiling techniques for STRAIGHT code generation and prove that our techniques can reliably generate code that satisfies the distance constraints. We implemented the proposed method on a compiler and evaluated benchmark programs compiled with it through simulation. The evaluation results showed that the proposed method works in all cases, including conditions where the number of registers is small and existing methods fail to generate code.