A portable specification of zero-overhead looping control hardware applied to embedded processors

Looping operations impose a significant bottleneck to achieving better computational efficiency for embedded applications. To confront this problem on embedded RISC processors, an architectural modification involving the integration of a zero-overhead loop controller (ZOLC) has been suggested, supporting arbitrary loop structures with multiple-entry and multiple-exit nodes. In this paper, a graph formalism is introduced for representing the loop structure of application programs, which can assist in ZOLC code synthesis. Also, a portable description of a ZOLC component is given in detail, which can be exploited in the scope of RTL synthesis, compiler optimizations or assembly level transformations for enabling its utilization. This description is designed to be easily retargetable to single-issue RISC processors, requiring only minimal effort for this task