一句话：提出 PYE 两步分析框架，静态编译生成条件值、JIT 阶段解析条件，实现精确且低开销的运行时分析。
Java、C# 等语言的 JIT 编译时间计入程序执行时间，因此 JIT 编译器常为效率牺牲分析精度；而纯静态全程序分析又因运行时库不可见而产生不精确结果。本文提出 PYE（precise-yet-efficient）两步分析框架：静态编译阶段执行昂贵分析，并针对运行时库缺失生成条件值形式的部分结果；JIT 编译阶段利用库的预计算条件值解析这些条件，得到最终精确结果。作者在 Soot 与 OpenJDK HotSpot Server Compiler（C2）中分别实现静态与运行时组件，并实例化为两种基于堆的上下文、流与字段敏感分析：用于空指针检查消除的指向分析，以及用于同步消除的逃逸分析。在大量基准上与 C2 中最先进的对应实现进行广泛对比，结果表明 PYE 同时兑现了精度与效率两方面的承诺。
Languages like Java and C# follow a two-step process of compilation: static compilation and just-in-time (JIT) compilation. As the time spent in JIT compilation gets added to the execution-time of the application, JIT compilers typically sacrifice the precision of program analyses for efficiency. The alternative of performing the analysis for the whole program statically ignores the analysis of libraries (available only at runtime), and thereby generates imprecise results. To address these issues, in this article, we propose a two-step (static+JIT) analysis framework called precise-yet-efficient (PYE) that helps generate precise analysis-results at runtime at a very low cost. PYE achieves the twin objectives of precision and performance during JIT compilation by using a two-pronged approach: (i) It performs expensive analyses during static compilation, while accounting for the unavailability of the runtime libraries by generating partial results, in terms of conditional values , for the input application. (ii) During JIT compilation, PYE resolves the conditions associated with these values, using the pre-computed conditional values for the libraries, to generate the final results. We have implemented the static and the runtime components of PYE in the Soot optimization framework and the OpenJDK HotSpot Server Compiler (C2), respectively. We demonstrate the usability of PYE by instantiating it to perform two context-, flow-, and field-sensitive heap-based analyses: (i) points-to analysis for null-dereference-check elimination; and (ii) escape analysis for synchronization elimination. We evaluate these instantiations against their corresponding state-of-the-art implementations in C2 over a wide range of benchmarks. The extensive evaluation results show that our strategy works quite well and fulfills both the promises it makes: enhanced precision while maintaining efficiency during JIT compilation.
DOI 原文 ·
@article{paperbot706,
title = {PYE},
author = {Manas Thakur and V. Krishna Nandivada},
journal = {ACM Transactions on Programming Languages and Systems},
volume = {41},
number = {3},
year = {2019},
doi = {10.1145/3337794}
}