Runtime organization for the Ada language system programs

Abstract

The runtime organization provides the execution environment for generated code of a source program. The runtime organization includes the primitive data elements, such as scalar and composite data objects; system data elements, such as stack and heaps; and a runtime system to provide functionality not supported in the target computer. In effect the runtime organization provides an abstract or virtual machine.This paper is a brief overview of the runtime organization that is the execution environment for the code generated by the Ada compiler in the Army Ada Language System. Since this compiler translates the full Ada language, the runtime organization must provide support not normally found in other languages, such as exception handling and tasking. As retargetability is a major goal of the Ada Language System, the runtime organization must also exist on many targets, both with or without an operating system support. While this paper specifically describes the runtime organization for the VAX/VMS 11/780, it does explore the design flexibility that enables the design to support generated code over a variety of targets.