一种优化的跨平台可逆调试器

针对大型软件系统中调试效率低下以及并发程序错误难以重现的问题，设计和实现了基于虚拟技术的可移植优化逆向调试器(PORD)．PORD动态翻译被调试程序的二进制可执行代码，并且在翻译过程中向检查点处植入代码来保存程序运行状态，使程序在执行过程中以增量的形式自动生成状态日志．PORD中集成的功能扩展的GDB远程控制虚拟机，根据检查点的状态日志重建历史执行状态，从而达到逆向执行目的．当被调程序与宿主机有相同的指令集架构时，动态二进制翻译就被优化为直接拷贝执行被调试程序的二进制可执行码，使被调程序能够以接近本地速度的速度执行．实验结果表明，PORD可以为程序提供快速的可移植的逆向调试环境．

Portable and optimized reversible debugger

Due to the low debugging efficiency of large scale software systems and the unrepeatable problem of concurrent program errors, we design a portable and optimized reversible debugging framework based on the Virtual Machine and present a prototype of the reversible debugger called PORD. PORD dynamically translates the executable binary code of the debuggee and instruments code at checkpoints to save execution states. When the debugee runs, the log of execution states is generated dynamically and incrementally. The extended GDB integrated in PORD controls the virtual machine remotely, and restores history states of debuggee according to the state log. If the Instruction Set Architecture of the debuggee is the same as that of the host, dynamic binary translation is replaced by dynamic binary copying for optimization, which enables the debugee to gain a near native speed. Experiments illustrate that PORD provides an efficient and portable software debugging environment at a reasonable speed.