Dynamic programming allows locally optimal instruction selection for expression trees. More importantly, the algorithm allows concise and elegant specification of code generators. Aho, Ganapathi, and Tjiang have built the Twig code-generator-generator, which produces dynamic-programming code-generators from grammar-like specifications. Encoding a complex architecture as a grammar for a dynamic-programming codegenerator -generator shows the expressive power of the technique. Each instruction, addressing mode, register and class can be expressed individually in the grammar. The grammar can be factored much more readily than with the Graham-Glanville LR(1) algorithm, so it can be much more concise. Twig specifications for the VAX and MC68020 are described, and the corresponding code generators select very good (and under the right assumptions, optimal) instruction sequences. Limitations and possible improvements to the specification language are discussed. 1. Introduction One of the last...

In an era of rapid design of microprocessors for desktop systems, embedded systems, and handheld computing devices, the timely construction of systems software is essential. Systems software, such as assemblers, compilers, and debuggers, must be constructed before development of application software for a microprocessor can commence. However, the implementation of such machine-specific applications is difficult and time consuming. Therefore, to remain competitive, it is imperative that systems software designs focus on portability to reduce implementation time and ensure rapid delivery of complete systems to the market. This dissertation presents the Computing System Description Language (CSDL) framework that addresses these rapid development requirements. We illustrate the CSDL framework by developing an instruction-set description component (RTL), an optional procedure calling convention description component (CCL), and the mechanism we use to extend extant descriptions (CSDL). RTL and its accompanying microinstruction descriptions (RTL) further the state-of-the-art in specifying semantics of machine instructions. RTL adds a new type system and abstract syntax that facilitates more accurate specification and automatic detection of errors by RTL manipulators. RTL machine descriptions are also application independent---they completely separate the specification of semantics from the application's implementation. The CCL specification language is the first work to formally describe procedure calling conventions. We demonstrate two distinct uses for CCL descriptions: code generation and fault detection. Using CCL we have built compilers that are more robust, and found and diagnosed faults in production compilers. CCL, RTL, and RTL descriptions are bound together u...

Abstract not found