Unable to compile wasm bytes in a isolate associated with v8::SnapshotCreator

[Yulan Wang]

I'm trying to use snapshot to cache the context with compiled code (JS source code and wasm bytes code) inside. I can go througth with JS code.

But for wasm, I can compile the wasm code in regular isolate, but once I declare SnapshotCreator in the code like follow line:

`Isolate::CreateParams create_params;

create_params.array_buffer_allocator =

v8::ArrayBuffer::Allocator::NewDefaultAllocator();

auto isolate = Isolate::New(create_params);

SnapshotCreator creator(isolate);`

WasmModuleObject::Compile doesn't work and return a non-WasmModuleObject. 

I also tried with v8::Script::Compile, and I got the same issue. The code works without SnapshotCreator declare, but doesn't work with SnapshotCreator. 

Is there any compiler restraint in SnapshotCreator that cannot compile wasm code, or I miss any configs?  Thanks!

[Clemens Backes]

Wasm support in snapshots was never added (see issue 8176). Supporting it would be a non-trivial amount of work, as we have to make sure to serialize the compiled Wasm code (living outside the JS heap) on snapshot creation, and properly reconstruct all involved functions and objects from that when deserializing.

Please go ahead and open an issue on http://crbug.com/v8/new and describe your use case, so we can include this in our planning for the upcoming quarters.

Cheers,

Clemens

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Clemens Backes

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clem...@google.com

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[Yulan Wang]

Thanks for your reply, Clemens.  I opened the issue 13430. Thanks!

Best,

Yulan

[Tudor Bosman]

Is there any chance that this can be resurrected / implemented?

I'd love to be able to snapshot large Emscripten apps (such as apps that use Pyodide).

Failing that, is there a way to detect if a Context has any WebAssembly hanging off of it anywhere, so I know to not even try to serialize it?

Thanks,

-Tudor.