CSR-EHS: Virtual-Machine Techniques for Resource-Constrained Devices: Reconciling Reliability With Reusability and Low Development Costs in the Embedded Systems Space

虚拟机（vm）是广泛使用的基于计算机的执行框架，它将应用程序与底层硬件和系统软件平台隔离开来，并实现编程语言的运行时语义。这个项目的重点是通过跟踪驱动的动态编译的方式在资源受限的设备上有效地执行虚拟机代码。许多在图上执行成本很高的优化算法可以在线性时间内在跟踪上执行。此外，跟踪导向的编译器可以以直接的方式内联方法调用，从而大大减少了面向对象编程的模块化开销，这是最关键的。因此，这种方法为嵌入式软件中良好的软件工程实践和面向组件的编程铺平了道路，而不会带来通常与这些技术相关的性能损失。该项目基于静态单赋值表单的一种新用法，初步结果为设计嵌入式混合虚拟机指明了一条全新的道路。主要的重点是系统地探索和进一步开发这种方法，最初的目标是Java虚拟机（JVM）平台。第二个重点是开发一个可扩展的VM层，该层的最佳位置是支持各种嵌入式软件，但它仍然可以有效地映射到当前和未来的嵌入式处理器平台上。嵌入式系统呈现的是一种“一次写入，之后永远运行”的计算范式，它还没有达到它真正的潜力。该项目有望在嵌入式软件的开发方式上带来重大改进。它将支持当前无法重用的嵌入式软件的重用，并简化向日益发展的嵌入式处理器的过渡。预计这将显著降低嵌入式软件的成本并显著提高其可靠性。

Virtual machines (VMs) are widely-used computer-based execution frameworks that isolate an application from the underlying hardware and system software platform and implement programming language run-time semantics.. This project focuses on efficient execution of virtual machine code on resource-constrained devices by way of trace-driven dynamic compilation. Many optimization algorithms that are expensive to perform on graphs can be performed in linear time on a trace. Furthermore, a trace-directed compiler can in-line method calls in a straightforward manner, significantly reducing the modularization overhead of object-oriented programming where it is most critical. This approach thereby paves the way for good software engineering practice and component-oriented programming in embedded software without the accompanying performance penalties that are often associated with these techniques. The project is founded on a novel use of Static Single Assignment form and preliminary results point the way to a completely new way of designing embedded hybrid VMs. The main focus is on systematically exploring and further developing this approach, initially targeting the Java Virtual Machine (JVM) platform. A second focus is on developing a scalable VM layer that is optimally situated to support a wide variety of embedded software, but that can yet be efficiently mapped onto current and future embedded processor platforms. Embedded systems present an application of the 'write once, run forever after' computing paradigm that has not yet reached its true potential. The project is expected to lead to significant improvements in the way embedded software is developed. It will enable reuse of embedded software where no such reuse is currently possible and simplify the transition to increasingly evolved embedded processors. This is expected to have impact in significantly lower cost and significantly increased reliability of embedded software.