CONSTRUCTION OF COMPILER FOR A PASCAL SUBSET UNDER UNIX ENVIRONMENT

Abstract

A compiler for a Pascal subset is constructed using the language development tools--lex. vacc and make, available on the UNIX system. It generates target code in M68020 assembly language for a given source program. This work is divided into four modules. 1.Lexical analyzer 2.Parser 3.Error handler and Intermediate code generator 4.Optimizer and code generator. Lexical analyzer is generated by giving a set of regualr expressions as input to Lex. Each regular expression is associated with an action routine for installing lexemes in Symbol and Literal tables. The grammar for the Pascal subset is written and given as input to Yacc, which in turn generates a parser. Error handler and intermediate code generator are implemented by incorporating appropriate action program segments in the grammar rules using Syntax Directed Translation. An attempt is made to optimize the intermediate code represented in indirect triples, and M68020 assembly code is generated with reasonable efficiency.