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Comment by tom_mellior | Hacker News Reader

> so don't bother shooting the messenger

OK, let's shoot the original source: It only found that a certain unnamed version of GCC ten years ago performed tail merging, which does indeed defeat the purpose of the optimization. Without the author bothering to turn off tail merging in this case (as Python does), this doesn't mean much.

> Comparing language performance is tricky business, but it mostly runs faster than Python3 from my tests so far.

Presumably you not only have a different interpretation approach, but also a different object model, approach to boxing numbers, and garbage collector. "Tricky business" is a bit of an understatement ;-)

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Better him than me. I wouldn't be so quick to dismiss relevant coding experience, it doesn't get old. Much of his reasoning about locality still holds, to an even greater degree today.

I've implemented more or less the same interpreter using computed goto and various variations on dispatch loops; and this is the fastest solution I've managed to come up with, and the nicest code to work with. Still too many parameters, my point is that I have plenty of experience pointing in that direction which is better than nothing. It's not a mystery to me. Using computed goto will involve some kind of lookup to get the relevant labels, I'm using pointers to actual instructions as jump targets. And since I'm longjmp'ing out, which means I don't need a loop condition; the loop is reduced to a single regular goto.

Like I said, better than nothing. There is no such thing as perfection in this world. I've spent quite some time [0] micro benchmarking different features to get a fair comparison.

[0] https://gitlab.com/sifoo/snigl/tree/master/bench

Oh, I wasn't dismissing experience in general, nor was I questioning your experiences. I would love to see your numbers on the different dispatch methods you tried.

I was only questioning that one blog post you linked that lazily said (paraphrasing) "computed-goto dispatch will be undone by the compiler, so don't bother". Others have posted numbers in this thread (https://news.ycombinator.com/item?id=18679477) showing that this information is at best outdated.

No harm done; I don't do pride any more, it kept getting in the way of truth. But there's a clear tendency, especially on HN if you ask me; to blindly trust research by whatever authority and beat people over the head with so called best practices; while completely disregarding personal experience.

Sometimes the reason no one finds a better solution for a long time is that no one believes it's possible. Let's say it's 50/50, believing it's possible is still the superior alternative.

I have no idea what Python uses for regular dispatch; the linked thread just says that their computed goto solution is faster, which comes as no surprise given that was the reason they switched.

I posted the link since I learnt a lot from it, and since it echoes my own experience.

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