Automatic source-code parallelization using HICOR objects

Abstract

We show that by using an intermediate representation, which supports a formalized interface on which to construct parallelization tools, the mapping of the representation onto parallel architectures can be performed quickly and efficiently. An intermediate representation called HICOR (Hierarchical Intermediate Code Object Representation) is shown to facilitate the exploitation of parallel operations by providing an abstraction layer for performing high-level intermediate code analysis, scheduling, and code generation. An object-oriented design approach has been employed in the development of HICOR and associated tools. Source language constructs are transformed into specialized object classes. Inheritance properties provided by the object-oriented paradigm are utilized to provide a common interface to each object in the HICOR representation. It is this interface that provides the needed consistency and flexibility in which to construct tools that has since been lacking. In particular, a tool to performCompile-Time Scheduling is presented. The scheduling algorithm employed differs from traditional scheduling problems in that merging of tasks is performed to reduce both task creation and communication costs in determining the final schedule. Architectural parameters are provided as input to the heuristic allowing the scheduler to produce near-optimal results for a wide variety of MIMD architectures. Once the final schedule is determined theTarget Code Generator, also presented, is used to generate the corresponding target code. A prototype system has been implemented in C++ which incorporates the HICOR intermediate representation with the tools described. The target architectures include the Sun 630 MP/4, Sequent Symmetry S81, and Stardent Titan.