becavalier / twvm

An experimental WebAssembly virtual machine.

TWVM

TWVM is still under continuously construction, not production-ready yet!

A tiny, lightweight, and efficient WebAssembly virtual machine.

Getting Started

Compile & Install

Please install the following softwares beforehand:

• cmake v3.11 (or above)
• nodejs v12.13.0 LTS (or above)

Then, run the following command to compile and install:

npm run build

How to use?

You can use the below command to invoke an exported function from a WebAssemly binary module:

# Invoke function `fib` with value 10.
twvm ./tests/modules/fibonacci.wasm -i=fib,10  # 55.

For further information, please run the below command for help:

twvm -h

Other Information

• Limitations:

Currently, TWVM can only run standard WebAssembly binary modules with the instructions in MVP standard. Also, please make sure the module doesn't require any import objects (.e.g memory, function, table, and etc).

• Memory Check:

Install "valgrind" on MacOS according to the following articles first:

How to Install Valgrind on macOS High Sierra

Valgrind on macOS 10.14/10.15

And then, run the below command to check the memory leak of the program:

npm run memcheck

Roadmap

• Architecture refactoring.
• Run simple fibonacci function successfully.
• Full Wasm spec version 1.0 support.
• Pass all basic testcases.
• DCT optimization.
• WAT support.

Copyright and License

Licensed under the MIT License.

twvm's Issues

Add some examples and guidelines

I have compile the project successfully but I can't find some guides to play with it.

I just build a hello.c with emscripten to hello.wasm, and then it fails..

twvm --debug hello.wasm

//////    //    //
  // //  ////  ////
  //  ////  ////  //
  //   //    //    //

  V.under-construction

twvm: info: - [LOADING PHASE] -
twvm: info: parsing type section.
twvm: info: parsing import section.
twvm: info: parsing function section.
twvm: info: parsing table section.
twvm: info: parsing memory section.
twvm: info: parsing global section.
twvm: info: parsing export section.
twvm: info: parsing element section.
twvm: info: parsing code section.
twvm: error: invalid opcode found.

Consider TTC instead of DCT?

With TTC, we can have a much more compact action frame that replaces the current 64bytes address value with an uint32_t relative offset.

Structurize the codebase with the namespace.

As titled.

TODO: Abstraction.

1. Separating the whole arch into different abstractions.
2. Adding sound type check analysis.
3. etc.

Lazy parsing the function code until invoking it.

As titled.

TODO: clang-tidy

As titled.

By reference for passing the smart pointer.

It depends on the situation.

Re-implement loader with unformatted IO APIs to improve the performance.

As titled.

Encapsulate the members of each class with corresponding getter and setter.

As titled.

TODO: Optimize DECLARE_MEM_LOAD_OP_METHOD.

Reuse stack frame.

TODO: Unify the way of exception-handling.

1. index comparison.
2. try..catch.