Modelling of Language Syntax and Semantics: The Case of the Assembler Compiler

Abstract

Application of software language technologies, whether analytical, transformational, or generational, in an industrial context is usually a taxing endeavour, with high demands in qualification levels of developers involved in it. Yet, if applied successfully, in the right places and with the right amount of effort, they promise high returns in terms of optimisation, effectiveness, validity and verifiability. In this paper, we report on our experience on writing a compiler for a complex second generation legacy programming language originally intended to be used on a mainframe. The business case for this product deals with companies migrating their software systems off the mainframe to cloud native or PC. Leveraging the documentation, available domain knowledge, several sample projects and a test suite, as well as several proprietary DSLs, we successfully modelled syntax and semantics of hundreds of instructions of that language, to the point of producing a compiler with a very limited group of compiler developers in limited time. The compiler is currently deployed at some of our customers and has received a top technology award from Microsoft. This report is meant to serve as a sample snapshot of how compilers can be built in the industry with software language engineering techniques. Traditional problems of compiler construction such as parsing or code optimisation either did not present a noticeable challenge or did not manifest themselves altogether in the course of this project, but MDE matters such as model transformation, modular design, the use of DSLs and meta-tools, were a constant concern. The focus of the report is in truthful representation of the domain as well as the details of the project, on reflection of the choices that were taken or could have been taken in the meantime, and on lessons learnt during the project.

Keywords

Syntax; semantics, legacy systems, knowledge extraction, experience report, software language engineering

Cite as:

Vadim Zaytsev, “Modelling of Language Syntax and Semantics: The Case of the Assembler Compiler”, Journal of Object Technology, Volume 19, no. 2 (July 2020), pp. 5:1-22, doi:10.5381/jot.2020.19.2.a5.

This article is accompanied by a video realized by the author(s).