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.wasm Target

Refer to cpp-target for some notes and port them here later.

Use https://github.com/RyanLamansky/dotnet-webassembly to write the .wasm binary.

Branching

  • .wasm's br instruction, when applied to a block, goes to its end; when applied to a loop, goes to its beginning. The label 0 refers to the innermost scope.
    • All loops must be wrapped by a block so that break is possible.
  • Label stack (of string or null for unlabeled) and iterator statement stack. Breaking a loop should be a br op of its .wasm scope index plus one (the surrounding block for the loop). If break or continue have no label, they affect the innermost loop.

.wasm Imports

Classes

  • It's not clear what is a native class. Address that question. Is it a class that includes definitiosn with native or add the same modifier to classes?
  • nativeSize is inferred for non-native classes.
  • Native classes:
    • Inheriting a native non-final class requires super constructor to only receive the previously allocated object.
    • FFI(memorySize = n) determines the memory size for the internal fields of the enclosing class (it covers the exact type, not the supertypes). Fields from subclasses use memory after that memory size plus memorySize of other supertypes (including Object).
  • new C1, will be similiar to a C malloc taking the FFI memorySize (if the class is not native, memorySize is inferred) plus the FFI memorySize from supertypes (including Object if C1 is not object) of C1 and invoking its initialiser.

Class Identifiers

Every type will have an unique internal number id. Use FFI(typeId = n) for that.

Derive the following initially:

  • 0 = undefined
  • 1 = null

An exception must be thrown if it's a duplicate number. Types will get an id automatically, using a sorted counter for efficiency.

It's not yet confirmed if needed, but certain generic types such as array, may need a pre-assigned id. For example, for unions and dynamic contexts, although some implemented interfaces may already help on their usage.

Ids of Arrays and Other Generic Types

If needed in the future, collect the id number of instantiations of generic types such as array and register them in the runtime statically, in case the runtime needs these.