What's this repository

This repository contains training materials and learning path about developing a WebAssembly JIT compiler for a beginner. But this repository doesn't contain any compiler implementation.

For beginners of WebAssembly compilers, the following issues are commonly encountered:

1. I am very interested in compilers, but production-level compilers are too complex and not suitable for beginners to learn.
2. The WebAssembly standard is extensive, and reading it line by line can be tedious and obscure.
3. The knowledge required for compiler development is vast, making it difficult to know where to start.

This repo aims to provide a smooth learning curve for beginners, allowing developers with no compiler experience to gradually learn the basics of WebAssembly compiler development.

Who is the reader of this repository

Beginner developers who are interested at WebAssembly & compiler and want to start working this domain.

Learning target of this repository

Develop a tiny Wasm 1.0 JIT compiler for arm64 with cmake and C++ 14. With following features:

1. Module parser
2. Export function call
3. Local variables
4. Arithmetic operation
5. Control flow instructions
6. Direct function call
7. Indirect function call
8. Global variable
9. Linear memory
10. Import function call

Out of scope:

1. Validation of the Wasm Module
2. Floating point instructions

Engineering requirement:

1. Use Cmake 3.10+
2. Use the .clang-format for code format. Doc
3. Use the .clang-tidy for linter. Doc
4. Enable the warning flags of of gcc -Wall -Wextra -Wpedantic -Wformat=2 -Wformat-security -Werror=format-security -Wcast-align -Wcast-qual -Wconversion -Wdouble-promotion -Wfloat-equal -Wmissing-include-dirs -Wredundant-decls -Wshadow -Wsign-conversion -Wswitch -Wuninitialized -Wunused-parameter -Walloca -Wunused-result -Wunused-local-typedefs -Wwrite-strings -Wpointer-arith -Wfloat-conversion -Wnull-dereference -Wdiv-by-zero -Wswitch-default -Wno-switch-bool -Wunknown-pragmas -Werror

FAQ

1. Why chose arm64 instruction set? Arm64 and x86_64 are most often used instruction set on consumer electronics. Since x86_64 instruction encoding is complex, arm64 is more friendly for beginner
2. Why use C++ 14? C++ is the most classic system-level programming language. It's friendly to interacting with operating system and JIT code. In meanwhile, it's more powerful than C. Using version 14 is due to some embedded compiler doesn't support C++17 and further.
3. Which operating system and compiler to use? No limit here. But some guide of this repo may assume developers are developing on a x86_64 Ubuntu 24.04 or later with gcc-arm64 cross compiler and testing with qemu user mode emulator. If someone is not using this setup, some steps need to be adapted.

Prerequisite knowledge

1. As a compiler developer, Compiler principle is the core knowledge
2. Emit machine code need solid knowledge about Computer Organization and Architecture
3. Load JIT code need to interaction with operating system, so Principles of Operating Systems is also necessary

For developers who have not systematically studied these principles in university or have not learned them thoroughly, it is strongly required to study or revise them. In Learning_Materials there are some recommended curses

What to do Next

For developers without basic knowledge of Wasm and arm64, start with Chapter 00.

Otherwise, start with Chapter 01, and then implement the compiler chapter by chapter