CSR---EHS: A VLIW Architecture and Compiler Framework for Time Predictability

时间可预测性对于硬实时和安全关键系统的正确性至关重要，例如汽车和飞机控制系统。然而，现代微处理器的体系结构设计主要集中在通过使用高速缓冲存储器、分支预测和推测执行等技术来提高平均情况性能，这会显著降低计算的时间可预测性，并且使得准确的最坏情况执行时间(WCET)分析变得非常困难。该项目正在设计一个高度时间可预测的VLIW体系结构，同时保持VLIW体系结构在高性能和硬件简单性方面的优势。该项目还研究了新的编译器技术来支持时间可预测的VLIW体系结构，包括调度感知的高速暂存存储器管理、使用隐式路径枚举(IPE)的完全和部分IF转换、编译器指导的NOP插入以消除流水线时序影响，以及面向WCET的编译器优化。该项目的成功有望加快时间可预测的VLIW处理器的设计、实现和部署，适用于各种硬实时应用，对嵌入式处理器行业和社会都有好处。开发的软件包通过PI的研究网站公开提供。

Time predictability is vital to the correctness of hard real-time and safety-critical systems, such as automotive and aircraft control systems. However, the architectural design of modern microprocessors has mainly concentrated on improving the average-case performance by using techniques such as cache memory, branch prediction, and speculative execution, which can significantly compromise the time predictability of computing and make the accurate worst-case execution time (WCET) analysis extremely difficult. This project is designing a highly time-predictable VLIW architecture while keeping the advantages of VLIW architectures in terms of high performance and hardware simplicity. The project also studies novel compiler techniques to support the time-predictable VLIW architecture, including scheduling-aware scratch-pad memory management, full and partial if-conversion with implicit path enumeration (IPE), compiler-directed nop insertion to remove pipeline timing effects, and WCET-oriented compiler optimizations. The success of this project is expected to accelerate the design, implementation, and deployment of time-predictable VLIW processors for a wide range of hard real-time applications, which can benefit both the embedded processor industry and the society. The developed software packages are made publicly available through the PI's research website.