Presidential Young Investigator Award: "Semantics-based Generation of Optimizing Compilers"

编写编程语言的正式描述正在成为标准实践。“形式语义”的根本好处是它构成了一个明确的参考标准，根据它可以回答有关程序含义的问题。此外，它还可以作为程序的数学推理基础，例如用于优化目的。虽然这些确实是实际的好处，但语言的其他实用方面通常不会反映在形式语义中，例如编译时和运行时之间的区别，是否需要自动垃圾收集，等等。在先前的研究中，提出了一种称为“高级语义”的技术来解决这些问题。主要结果是，对于类pascal语言，高级语义允许自动生成真实的编译器。不幸的是，这种技术不容易扩展到包含多态性、非严格性、并发性等概念的更高级的语言。指针算术和易失性变量等低级特性也可以防止出现问题。也许最重要的是，基于语义的优化技术很难整合。在这个项目中，将开发正式描述和自动实现这些高级语言特性和优化的技术。目标是为高级语言自动生成几乎实用的编译器。

It is becoming standard practice to write formal descriptions of programming languages. The fundamental benefit of a "formal semantics" is that it constitutes an unambiguous standard of reference against which questions about the meaning of programs can be answered. Also, it serves as the basis for mathematical reasoning about programs, for instance for the purposes of optimization. While these certainly are practical benefits, other pragmatic aspects of languages are not normally reflected in a formal semantics, such as the distinction between compile-time and run-time, whether automatic garbage collection is needed, and so on. In previous research, a technique called "high-level semantics" was proposed which addressed some of these issues. The main result was that for Pascal-like languages, high-level semantics allows one to generate realistic compilers automatically. Unfortunately, this technique does not extend easily to more advanced languages incorporating such notions as polymorphism, nonstrictness, concurrency and so forth. Low-level features such as pointer arithmetic and volatile variables also prevent problems. Perhaps most importantly, semantics-based optimization techniques are hard to incorporate. In this project, techniques for formally describing and automatically implementing such advanced languages features and optimizations will be developed. The goal is to automatically generate nearly practical compilers for advanced languages.