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by vlovich123 1653 days ago
To add onto that, I tried several different hand rolled alternatives to a c++ vtable and the builtin functionality outperformed them all which was surprising. It’s entirely possible I didn’t know what I was doing but I think my point is that vtables are a language feature that compilers know how to reason about and apply optimizations to. Other concepts not so much.
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Something to keep in mind when microbenchmarking virtual calls is that compilers will happily devirtualize them whenever possible.
Yeah I’m aware but I made sure the same devirtualization would apply in production too so the compiler doing any devirtualization was good. It was a bit surprising that vtables outperformed std::variant (and I had tried implementing my own hand rolled equivalent of that too).