Compiler prototyping using formal semantics

The descriptive techniques of formal semantics can be used for the generation of complete prototype compilers. First, we review the essential characteristics of such semantics implementation systems, and discuss our experience with two existing experimental systems. Then, we show how to derive a complete conventional compiler for a small language from its denotational semantics. The compiler is specified in three phases consisting of a front-end (parser, tree builder, and semantic checker), a translator from syntax trees to prefix code, and a code generator which converts the prefix code into IBM/370 style assembly code. The translator component is obtained by modifying the standard semantics of the language in two steps: first, the semantic domains and the equations are rewritten in a straight forward way to achieve a normal form, and then the auxiliary semantic functions are interpreted as instructions for a prefix code machine. The entire three part specification has been implemented with the help of Paulson's semantics processing system.