An Ada code generator for VAX 11/780 with Unix

Abstract

This paper describes the final phase of an Ada compiler which produces code for the VAX 11/780 running the Unix operating system. Problems encountered in the implementation of subprogram calls, parameter passing, function return values, and exception handling and discussed and their solutions outlined.An underlying requirement for the code generator has been speed of implementation consistent with being a test bed for an Ada implementation. To accomplish this, a common model for the target environment has been assumed. The assumptions include: the VAX is a stack machine, a single address space is used, only the general case is implemented (no optimization of special cases), the hardware does as much work as possible, run time routines for lengthy code sequences are acceptable, and the conventions given in the VAX architecture, hardware, and software manuals are used.The code generator has been running on PDP-10 with Tops-10, producing a VAX assembly language source program as output. it has been available to local users since the beginning of 1980.