Insights into performance of tail calls.

[yurydelendik]

I'm trying to follow up on the following articles:

• https://leaningtech.com/blog/2020/08/18/extreme-webassembly-2-the-sad-state-of-webassembly-tail-calls/
• https://leaningtech.com/blog/2022/07/11/fantastic-tail-calls-and-how-to-implement-them/

Currently, Firefox/SpiderMonkey landed Wasm tail calls patches. And I was pleased to see https://webvm.io/ works (it loads/runs different cxcore.wasm), but cannot find any details on why tail calls are important for performance of x86 virtualization. More specifically, there is a need to construct simple benchmarks for this specific use case. Can you provide couple of pointers on how to build these?

Running webvm in Firefox Nightly with tail calls enabled/disabled I see about the same numbers by running time python3 examples/python3/fibonacci.py. Am I doing it wrong?

Thank you.

[alexp-sssup]

Tails calls are important to efficiently implement indirect jumps, we wrote an extensive write up on the matter that you might have missed.

https://leaningtech.com/blog/2020/06/16/extreme-webassembly-1-pushing-browsers-to-their-absolute-limits/

Since the time the blog post was written we have implemented quite a few improvements in CheerpX that mitigate the impact though, in particular we figured out a technique to make the indirect jump on library calls less of a problem.

Closing since this repository is about Cheerp (C++ to WebAssembly/JavaScript compiler), not about CheerpX (x86 on Wasm VM and JIT). For further discussion consider joining our discord: https://discord.gg/yTNZgySKGa