Effective Compilation in the Presence of Exceptions

Java被设计成一种成熟的、面向对象的编程语言，主要用于基于web的编程。但是，Java也可以支持一般的独立应用程序，例如由独立组件组成的科学代码，这些组件使用异常作为组件之间的控制机制。尽管Java太新了，还没有在应用程序中广泛使用，但很明显，用户定义的异常将在Java程序中无处不在，导致它们表现出与以前的面向对象语言不同的独特控制流。提出的研究集中在结合新的分析技术和两种优化策略，即投机和非投机，使用科学应用的测试平台进行验证。异常给优化编译器带来了新的挑战，因为它们引入了隐式控制流，并且它们的语义要求在任何引发的异常时访问用户可见的状态。优化策略可以保留异常及其可见状态，也可以通过忽略异常来执行推测性优化，并在引发异常时恢复可见状态。需要新的静态分析来提供对方法边界内和跨方法边界的控制流的准确估计，包括具体的类型推断和随后的defuse分析。结果信息对于许多优化的有效性至关重要，包括代码专门化、代码运动、寄存器分配和指令调度。

Java is designed to be a mature, object-oriented programming languagemainly for Web-based programming. However, Java can support general stand-alone applications as well, such as scientific codes that consist of independent components using exceptions as a control mechanism between components. Although Java is too new to have been used extensively in applications, it is clear that user-defined exceptions will be ubiquitous in Java programs, causing them to exhibit distinctive control flow, different from previous object-oriented languages. The proposed research concentrates on combining new analysis techniques with two optimization strategies, namely speculative and non- speculative, using a testbed of scientific applications for validation. Exceptions pose new challenges to optimizing compilers since they introduce implicit control flow and their semantics requires access to user-visible state at any raised exception. Optimization strategies may either preserve exceptions and their visible states, or perform speculative optimizations by ignoring exceptions, and restore the visible state if an exception is raised. New static analyses are needed to provide an accurate estimate of control flow within and across method boundaries, including concrete type inference and subsequent def-use analyses. The resulting information is crucial for the effectiveness of many optimizations, including code specialization, code motion, register allocation, and instruction scheduling.