一個嵌入式之Java即時編譯器架構

Abstract

Java技術已經是現今嵌入式系統市場上不可或缺的一員。然而發展具備執行Java程式能力的嵌入式系統是一項費時費力的工作。除了滿足Java虛擬機器本身的規格之外，軟體工程師必須在有效運用有限的硬體資源如記憶體及電源消耗等的前提下發展高效率的Java虛擬機器。在本論文中，我們針對嵌入式系統發展一個可擴充的Java指令即時編譯器架構。為了達到簡單易懂及可擴充的目的，此系統是以昇陽公司的標準KVM實作為基礎發展的。此編譯器架構包含一個單一的中介表示法來允許不同層級的最佳化分析。我們已經開發了幾個利用此架構的程式、還有測試的例子，並產生出一些初步的效能測試結果。我們的目標為發展一個可根據資源使用的現狀而調整最佳化程度的即時編譯器。雖然這個架構的發展仍在進行，但初步的成果已能作為未來發展的基礎。

The Java technology is becoming relevant in the emerging embedded systems trend. However, to develop a Java-enabled embedded system requires substantial engineering effort. First of all, the Java virtual machine itself is nontrivial. In addition, to operate in restrictive operating conditions often endured by embedded systems, the JVM should be sufficiently efficient yet consume as little memory and power as possible. In this thesis, we develop an extensible JIT compiler framework for embedded systems. To be extensible and adaptable, the JVM is based on the popular KVM implementation that is small, portable and modular. Furthermore, an optimization framework with a just-in-time compiler as well as a common intermediate representation is developed to permit different types of optimizations. We have built several applications and test cases using the framework, and conducted some initial performance studies. Although the development of the framework is an on-going process and many issues remain to be resolved, we have found that our approach can serve as a good foundation for embedded Java.