CAREER: Better Systems With Extensible C

随着系统越来越多地集成到全球计算环境中，一个关键的挑战是如何管理由此产生的软件复杂性。元编程可以帮助应对这一挑战。为了调和语言/编译器工作和系统实践之间的差距，这项工作将探索以下研究问题：如何安全地扩展不安全的低级别编程语言C，包括使用新的定义结构（如对象）和新的类型（如类），以及如何将语言和编译器扩展分解以最大化重用，以及管理和组合最终的细粒度扩展需要什么支持。该项目将为C开发和构建一个宏系统，称为可扩展C的xtc，但与C预处理器不同，xtc宏是作为程序抽象语法树（AST）上的转换指定和实现的，并保持宏的健康。该项目还将探索一些方法，如支持复杂AST转换的树查询语言，支持引入新类型的可扩展类型系统，以及如何禁用选择语言特性（如指针），以及如何表达特定于领域的编译器优化。使用xtc构建的软件将更加可靠和安全，随着企业和政府越来越依赖IT来维持生计，这一点至关重要。此外，通过开放C语言，提议的工作可以使语言和编译器研究人员产生更大的影响，教育工作者可以更容易地探索计算机科学教学的新方法。为了强调最后一点，该项目将在所有适当的课程（包括研究生级别的编译器）中利用xtc，还将开发一门新的面向对象编程本科课程和相应的教科书，这些课程不仅探索相关概念，而且探索它们的底层实现（作为xtc宏）。

As systems are increasingly integrated within a global computing environment, a crucial challenge is how to manage the resulting software complexity. Metaprogramming can help meet this challenge. To reconcile the gap between language/compiler efforts and systems practice, this work will explore the following research questions: how can an unsafe and low-level programming language, C, be safely extended, including with new definitional constructs, such as objects, and new kinds of types, such as classes and how can language and compiler extensions be factored to maximize reuse, and what support is necessary for managing and composing the resulting fine-grained extensions . The project will develop and build a macro system for C, called xtc for eXTensible C, but unlike the C preprocessor, xtc macros are specified and implemented as transformations on a program's abstract syntax tree (AST) and preserve macro hygiene . The project will also explore methods such as a tree querying language that supports complex AST transformations, an extensible type system, which supports the introduction of new kinds of types, and will investigate how to disable select language features, such as pointers, and how to express domain-specific compiler optimizations. Software built with xtc will be more reliable and secure, which is of critical importance as business and government increasingly depend on IT for their livelihood. Furthermore, by opening up C, the proposed work enables language and compiler researchers to have more impact and educators to more easily explore new approaches to teaching computer science. To emphasize the last point, the project will leverage xtc in all appropriate courses, including the graduate-level compilers and will also develop a new undergraduate courseon object-oriented programming and the corresponding textbook, which explore not only the relevant concepts but also their underlying implementation (as xtc macros).