ilwasm

Maps a subset of .NET CIL to WebAssembly S-expressions. Implemented as a custom code generator backend for the JSIL CIL -> JS compiler.

Building on Windows

Make sure you have Visual Studio 2015 (the free Community edition is fine). Build JSIL (third_party/JSIL/JSIL.sln), then build WasmSExprEmitter & WasmMeta (WasmSExprEmitter.sln).

Building on Linux

A recent version of Mono is required for C#6 support and NuGet compatibility. If you don't have a recent version of Mono installed, run third_party/JSIL/install-mono.sh once to download & build from source, then do source third_party/JSIL/activate-mono.sh to load it into your current environment.

Build JSIL (third_party/JSIL/linux-build.sh), then build WasmSExprEmitter & WasmMeta (linux-build.sh).

Writing tests

Tests are placed in the third_party/tests directory as .cs files. A test has a single entry point (typically Program.Main) that accepts no arguments and has no return value.

The entry point's body must contain only calls to APIs from Wasm.Test, like SetHeapSize or AssertEq. Constants are fine but locals, branching or other behavior are not allowed in the entry point, as it is converted into top-level wasm assertions.

Exports

A test can export static methods with the Wasm.Module.Export attribute, like so:

[Export]
public static void Exported () {}
[Export("customName")]
public static void AlsoExported () {}

Exported methods can be invoked by name in the entry point by using the Test.AssertEq and Test.Invoke APIs.

Heap

Tests requiring access to the heap must first reserve it using the Test.SetHeapSize API. To read/write the heap use the fields of the Wasm.Heap class, like so:

Wasm.Heap.I32[offset] = value;
value = Wasm.Heap.U8[@base, offset];

The heap is not accessible externally (i.e. in the entry point) so to perform assertions against heap data, you must expose the heap via an exported function.

Fields and properties

Static fields of supported types work. To access a field's value from outside, export accessor methods, or simply define it as an exported property:

[Export]
public static int Property { get; set; }

Types

Currently only integral and floating-point types are supported. Functions and variables of other types will be ignored (or outright rejected) by ilwasm.

Future features

Structs
ref/out parameters
Pointers

uranium62/ilwasm