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Contributing

Debugging

For easy debugging, run IL2Wasm.CLI in debug mode. This will compile IL2Wasm.BaseLib into WAT format. You can then test or validate this output using the wat2wasm online demo.

Supporting new IL Instructions

If you're debugging IL2Wasm-compiled WAT and come across a line that looks similar to:

;; Unhandled operand: Call (MyNamespace.MyMethod)

or

;; Unhandled opcode: Nop

That means the compiled C# code contains an IL instruction that IL2Wasm does not support. An IL instruction represents a single operation in the Common Intermediate Language (CIL), describing exactly what the program should do. IL2Wasm’s primary role is to translate these C# IL instructions into equivalent instructions that WebAssembly can execute.

So, how can we add support for a new IL Instruction?

First, understand the instruction and it's purpose. A helpful resource is Wikipedia's 'List of CIL instructions', though other references are also available.

Next, open ILInstructionHandlers.cs and add a new Instruction Handler. A typical handler looks like this:

[ILInstructionHandler]
internal class PopHandler : BaseInstructionHandler
{
    public override bool CanHandle(Instruction instr) => instr.OpCode.Code == Code.Pop;
    public override string Handle(Instruction instr) => "drop";
}

This Instruction Handler converts C#'s Pop to WASM's drop. CanHandle tells the compiler which instructions this handler can process, while Handle generates the corresponding WAT instructions.