Scalable Optimization of Generic Java

通用 Java 的可扩展优化

• 批准号: 0105596
• 负责人: Robert Cartwright
• 金额: $ 22万
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0105596&HistoricalAwards=false
• 关键词: Scalable; Optimization; Generic; Java

Java programmers rely on clumsy "erasure" idiom to define generic operations: a generic class is represented by conventional classes where all references to type parameters have been replaced by the type Object. Programs that rely on this idiom must repeatedly cast the results of generic operations to the types of omitted type parameters. Generic operations in Java are slower than their non-generic counterparts because this idiom introduces a level of indirection in the representation of type parameters instantiated as primitive types.The investigator has recently completed the construction of a prototype compiler for NexGen, a Java extension supporting genericity designed by the investigator and Guy Steele. The compiler relies on the erasure idiom to implement genericity and hence does not improve the performance of computations involving generic classes.To produce good performance for generic Java, a compiler must eliminate indirection in the representation of generic class instances. The requisite transformation is called {\em whole program analysis} because it is invalid if any program operation depends on the address of an inlined object. Fortunately, there is a nearly linear algorithm based on previous work by the investigator on concrete type analysis that can determine if a given object field can be inlined.This project will develop a new optimizing compiler for NextGen that uses concrete type analysis to inline the parametric fields of generic classes.

Java 程序员依靠笨拙的“擦除”惯用法来定义泛型操作：泛型类由常规类表示，其中对类型参数的所有引用都已替换为 Object 类型。 依赖此习惯用法的程序必须重复地将泛型操作的结果转换为省略的类型参数的类型。 Java 中的泛型操作比非泛型操作慢，因为这种习惯用法在实例化为原始类型的类型参数的表示中引入了一定程度的间接性。研究人员最近完成了 NexGen 的原型编译器的构建，NexGen 是一个支持泛型的 Java 扩展由调查员和盖伊·斯蒂尔设计。 编译器依靠擦除惯用法来实现泛型，因此不会提高涉及泛型类的计算的性能。为了使泛型 Java 产生良好的性能，编译器必须消除泛型类实例表示中的间接性。 必要的转换称为“整个程序分析”，因为如果任何程序操作依赖于内联对象的地址，则该转换是无效的。 幸运的是，基于研究者之前关于具体类型分析的工作，有一种近乎线性的算法，可以确定给定的对象字段是否可以内联。该项目将为 NextGen 开发一个新的优化编译器，它使用具体类型分析来内联参数泛型类的字段。