Introduction
前言
项目路径：https://github.com/P2Tree/LLVM_for_cpu0
介绍
这个项目是一个学习 LLVM 的教程，我实现了一个 LLVM 框架下的后端，用来编译能够在 Cpu0 上执行的可执行代码，Cpu0 是一个简单易学的 RISC 处理器。另外，我还编写了一份详细的中文文档作为 LLVM 初学者的指南，它们放在 tutorial 路径下。
这个目录和其子目录下包含着完整的 LLVM 的源代码，目前是 8.0.0 版本，以及用于构建优化编译器、优化器和运行时环境的工具包。
大多数代码都放到 src/lib/Target/Cpu0 这个路径下，不过也有少量代码在其他位置，配合修改了公共代码。
使用方法
你可以把文档的每个章节作为指南来阅读和学习，并把工程中的代码作为参考。 我把每个章节修改过的文件都放到了 shortcut/ch_x 的各个路径下，如果在编码时有困惑，可以辅助查看。 我知道，目前代码和文档里依然会有问题，如果你有任何疑问，欢迎告知我。
感谢
正如我在文档中写到的，教程文档高度参考了一本教程，这个教程叫 Tutorial: Creating an LLVM Backend for Cpu0 Architecture，其作者叫 Chen Chung-Shu，他的教程对我学习 LLVM 非常有帮助。不过，因为完成较早，教程依赖的 LLVM 版本比较旧，大概是 3.0 版本，所以我重新用新版本实现了一遍。 所以，我诚挚的感谢 Chen Chung-Shu，感谢他的细致工作。
Preface
Project path: https://github.com/P2Tree/LLVM_for_cpu0
Introduction
This is a tutorial to learn LLVM, I realize a backend in LLVM infrastructure to compiler execute code for Cpu0 which is a simple RISC cpu. And I also write a detailed tutorial document by Chinese as a guidance for Chinese LLVM beginner. You can find it in the toturial.
This directory and its subdirectories contain source code for LLVM ( LLVM 8.0.0 currently ), a toolkit for the construction of highly optimized compilers, optimizers, and runtime environments.
Most of the code about Cpu0 backend is located in the src/lib/Target/Cpu0 but some are in other path to change public code.
Usage
You can read and learn each chapter in the document for a guide and use code of this project as a reference. I put every changed file into the shortcut/ch_x and you can check it if you have some trouble with coding. I think there are also have some bugs and drawbacks in the document and the code, please feel free to tell me if you have any problem.
Grateful
As I told you in the document, this tutorial document is reference extensively to a guide with Chen Chung-Shu which name is Tutorial: Creating an LLVM Backend for Cpu0 Architecture, this guide is very helpful for me to learn LLVM. As the guidence is so old with LLVM ( LLVM 3.0 probably ), I achieved again with a new version of LLVM. So I express heartfelt thanks to Chen Chung-Shu and his careful work.