* Support polyfilling multi-memory
Currently JS does not generally support the WebAssembly multi-memory
proposal. Wasmtime will, however, generate adapter modules which use
multi-memory to communicate between components. This means that composed
components are typically not compatible with the transpile process as
they produce a core module that doesn't actually run in any JS runtime.
This commit fixes this issue by adding polyfill support for
multi-memory. Whenever an adapter is produced that uses multi-memory jco
will now rewrite the module such that any references to memory that
isn't at index 0 to be indirected through functions. These imported
functions then operate on the specified memory on behalf of the wasm
itself. This is a horribly slow process because all memory reads/writes
become function calls, but given that the baseline is otherwise "does
not work" it's hopefully a bit better than before.
The end goal here is to work up towards strings between components, but
for now this just gets everything else working with multi-memory such as
transferring lists.
* Fill out comments
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Co-authored-by: Guy Bedford <gbedford@fastly.com>
Guy Bedford
Eduardo de Moura Rodrigues
Alex Crichton