Re:Maybe you don't need Rust and WASM to speed up your JS (2...
by jerf on Friday June 25, 2021 @09:16AM
(#27630381)
WASM couldn't be a 50-100x improvement over (optimized) JS because that would make it something like 10x faster than C. C isn't necessarily the absolute upper limit, it does have a couple of systemic flaws in terms of going absolutely the fastest (aliasing issues), but there certainly isn't that much room for improvement in it.
WASM will probably get faster, but I don't necessarily expect Rust-generated WASM or other static language-generated WASM to get that much faster. I think most of it will come from JIT'ing stuff that will mostly affect dynamic language-generated WASM. That said I do think Javascript's JIT is going to be fairly close to the limit of what you can see in WASM either, because it is implausible that you could "just" compile the JS to WASM then use the WASM optimizer to do better than the Javascript JIT. The Javascript JIT has everything the WASM optimizer would have, and more, since there would inevitably be loss in the translation.
WASM will probably get faster, but I don't necessarily expect Rust-generated WASM or other static language-generated WASM to get that much faster. I think most of it will come from JIT'ing stuff that will mostly affect dynamic language-generated WASM. That said I do think Javascript's JIT is going to be fairly close to the limit of what you can see in WASM either, because it is implausible that you could "just" compile the JS to WASM then use the WASM optimizer to do better than the Javascript JIT. The Javascript JIT has everything the WASM optimizer would have, and more, since there would inevitably be loss in the translation.