Graph-Based Mobile-Code Representations for High-PerformancePortable Software

CCR-9901689“用于高性能可移植软件的基于图形的移动代码表示法”Michael Frans这个项目研究移动代码应用程序的与机器无关的程序表示法。现有的方法都是基于抽象机器的：每个程序都被编码为虚拟机器指令集中的一个线性“字节码”序列。相反，这项研究侧重于分层的、基于图的格式，这些格式能够在比线性表示更高的程度上保留原始源程序的高级语义。在处理高性能软件中的显式源代码级并行性时，这一点变得尤为重要：通过没有层次结构的表示来传输这类程序意味着在编译源代码时进行序列化，并可能在最终的本机代码生成器中进行后续的重新并行化。这不仅代价高昂，而且很可能导致效率下降。此外，分层编码方案承诺直接和空间高效地编码高级代码优化所需的大部分控制流和数据流信息，以及提供更简单的移动代码安全性验证。最后，初步证据表明，对于抽象机器，分层解决方案比基于线性字节码流的解决方案更适合大型程序。

CCR-9901689"Graph-Based Mobile-Code Representations for High-Performance PortableSoftware"Michael FranzThis 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 sourceprogram to a much higher degree than linear representations. This becomes particularly important when dealing with explicit source-levelparallelism 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.