A Correspondence Between Denotational Semantics and Code Generation

my father- in memoriam. my mother, Daniel, my sisters and brothers.- II-We describe a method for the systematic derivation, or automatic generation- from the formal denotational semantic specification- of an efficient compiler's code generation phase, producing efficient code for real machines. The method has been successfully implemented and tested with languages as complex as GEDANKEN! The method has been used to implement a compiler-compiler which inputs the semantic specification of a programming language written in a standard denotational form, analyses it in the light of its semantic contents, decides upon certain predecided general implementation issues and outputs a program written in the systems programming language BCPL. This program constitutes the type.checking and code generation phases of a compiler for the given language. Its structure and operation is in effect essentially the same that we would have produced by hand. The only hand coding is the interface for the particular target machine, required for both the primitive functions of the original specification and those introduced by the compiler-compiler. For the latter, our system provides a library of routines to generate code for the DEC-10 system. So that in all the examples we tried, we only had to hand code the former. The parser is separately generated with an LLl system which also generates BCPL procedures