"Graph-Based Mobile-Code Representations for High-Performance Portable Software" Michael Franz
This project investigates machine-independent program representations for mobile-code applications. Existing approaches have been based on abstract machines: each program is encoded as a linear sequence of "byte-codes" in the instruction set of the virtual machine. This research instead focuses on hierarchical, graph-based formats that are able to preserve the high-level semantics of the original source program to a much higher degree than linear representations. This becomes particularly important when dealing with explicit source-level parallelism in high-performance software: transporting such programs via a representation without hierarchical constructs implies sequentialization when the source code is compiled, and possibly a subsequent re-parallelization in the eventual native-code generator. This is not only costly, but very likely to lead to a loss of efficiency. Moreover, hierarchical encoding schemes promise to directly and space-efficiently encode most of the control-flow and data-flow information necessary for advanced code optimizations, as well as provide for simpler verification of mobile-code security. Lastly, preliminary evidence suggests that hierarchical solutions scale better to large programs than solutions based on linear byte-code streams for abstract machines.
