Incremental Machine Descriptions for GCC

The mechanism of providing machine descriptions to the GCC framework has been quite successful as demonstrated by a wide variety of the targets for which a GCC port exists. However, this mechanism is quite ad hoc and the machine descriptions are difficult to construct, understand, maintain, and enhance because of the verbosity, the amount of details, and the repetitiveness. The publicly available material fails to bring out the exact abstractions captured by the machine descriptions. There is no systematic way of constructing machine descriptions and there are no clear guidelines on where to begin developing machine description and how to construct them systematically. This paper proposes a methodology based on incremental construction of machine descriptions starting from a well defined minimal machine description. We illustrate the process by constructing machine descriptions with the spim simulator for MIPS architecture as the target.