Compiling Erlang via C

This paper discusses the implementation of an Er-lang compiler which provides native compilation using C as an intermediate language. The intermediate output, while not elegant, is amenable to being ported away from the Erlang environment and into morètraditional' C based development environments. The compiler also provides a number of special features. These features include support for a concurrent monitoring system and simple static type analysis. Each Erlang module is compiled as a native shared object library to support dynamic code loading and unloading. In contrast to the standard Erlang implementation the runtime system is tightly integrated into the Unix environment. Er-lang processes are instantiated as actual Unix processes at runtime. This allows Unix system analysis and monitoring tools to be used upon individual Erlang processes. Overall this compiler ooers linear some computational performance improvements over standard Erlang systems while being highly portable and producing a re-usable intermediate code. The Erlang compiler, Gerl, described in this paper is a tool implemented as part of the support framework for a continuous software monitoring system. The compiler is intended to instrument system application code to automatically provide this monitoring system for the developer. The monitoring framework is described in 14]. There were a number of motivations for developing a new compiler. Primarily it was important that the design of the compiler included monitoring support as a central design feature of the system. It also allows the monitoring framework support to be built into the compiler in a modular way. This is important as the framework support is intended to be reused within other compilers. And nally it enabled the development of a fuller understanding of the mechanisms and performance issues related to implementing the monitoring framework. In developing the compiler a number of interesting implementation issues were explored: Translation of a functional language into an imperative form, particularly function poly-morphism, pattern matching, last call optimi-sation and exception handling. Implementing Erlang's highly concurrent process model. The issue of eecient garbage collection. The runtime support environment including integration with Unix and the runtime loading, linking and updating of compiled code. The performance of the compiler versus the existing virtual machine based implementations. This following sections discuss each of these issues in more detail. Problems areas and implementation choices are outlined and the chosen solutions are presented. 2 Translating Erlang to C Erlang code is compiled using C as an intermediate language. C ooers a variety …