C Compiler Retargeting Based on Instruction Semantics Models

Efficient architecture exploration and design of application specific instruction-set processors (ASIPs) requires retargetable software development tools, in particular C compilers that can be quickly adapted to new architectures. A widespread approach is to model the target architecture in a dedicated architecture description language (ADL) and to generate the tools automatically from the ADL specification. For C compiler generation, however, most existing systems are limited either by the manual retargeting effort or by redundancies in the ADL models that lead to potential inconsistencies. We present a new approach to retargetable compilation, based on the LISA 2.0 ADL with instruction semantics, that minimizes redundancies while simultaneously achieving a high degree of automation. The key of our approach is to generate the mapping rules needed in the compiler´s code selector from the instruction semantics information. We describe the required analysis and generation techniques, and present experimental results for several embedded processors.