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Comment by uasm | Hacker News Reader

> "WASM translated to register-based bytecode. That's awesome!"

If the hardware executing this code is "stack-based" (or, does not offer enough general purpose registers to accomodate the funtion call) - this will need to be converted back to a stack-based function call (either at runtime, or beforehand). Wouldn't this intermediate WASM-to-register-based-bytecode translation be redundant then?

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You seem to be asking something like "if we always hit the algorithm's slow path, isn't the algorithm slow?". The answer is "yes, but we will (hopefully) almost never hit the slow path". On x64-64 you will typically be able to pass 6 integer/pointer values and 8 floating-point values in registers. That should be enough for most function calls in real-world code.

I don't know of any current physical stack machine CPUs.

Stacks are used extensively across the x86 family [0]

[0] - https://en.wikipedia.org/wiki/X86_calling_conventions

"Has a stack" isn't the same as "Has a stack based ISA".

To expand: a Forth machine or similar would be a stack based ISA. Using a stack is a different matters; Pretty much every ISA uses stacks.

No, stack machine CPUs are pretty obscure things, especially today. See the link below for some examples. All or virtually all modern commercial CPUs are register based.

https://en.wikipedia.org/wiki/Stack_machine#Commercial_stack...

What proportion of machines running web assembly are stack-based, would you say?

I would guess negligible.

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