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Caching of compiled code! As i read it they want to cache the wasm bytecode at the client level. What if servers did the caching instead? Group clients by the architectures they use and serve the cached bytecode to the right 'groups' of clients.

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That would assume you trust the server not to give you malicious machine code (which you of course cannot!). wasm is specified in such a way that it is still sandboxed by the VM that compiles it. If you fetch arbitrary machine code, you cannot verify it and that leads to huge security holes!

> which you of course cannot!

Didn't Google's NaCL implement verification of sandboxed machine code?

Maybe, but at what cost? I wouldn't be surprised if the cost of verifying the machine code was higher than the cost of compiling wasm to machine code.

Why can’t you just cache it with a hash?

How would the client know the hash is valid?

Perhaps he means you compile the code locally, hash it, and then next time you can fetch the compiled code from a server, and check the hash matches?

That's possible; a kind of second-level cache. That assumes the compilation is reproducible, though.

Compiling wasm also enforces security rules. Offloading that would require full trust of the server, which is probably not desirable.

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