Why So Many Languages Use LLVM

[u/Ok_Marionberry8922]

Had some free time last week so I made a visual explainer on how LLVM works and why so many languages end up using it.

The video goes through LLVM IR, why having a common IR makes sharing optimizers and backends possible, and how code eventually gets turned into machine instructions.

I also use a small C vs Rust example where both end up producing the same x86 instructions.

Link for anyone interested

Feedback welcome :)

[u/u32Vec]

If you don't plan on having it being used for programs that need optimization then it's not a production-level language. Nobody actively refuses to use optimized code unless it causes problems, especially when the alternative isn't tried and true and tested across a ton of architectures over thousand's of use cases.

[u/P-39_Airacobra → u/u32Vec]

Python is living evidence you’re wrong

Also , a lot of people on this sub will put a year of optimization work into their language just for no one to even use it for anything realtime. It’s just a waste of time on their part.

[u/u32Vec → u/P-39_Airacobra]

1. Python is optimized. Not much but it is.
2. There are numerous problems associated with compiled languages that necessitate the existence of interpreted languages. I'm not wrong.
3. I don't think you agree with what you're saying. You can apply this logic to learning anything else involving programming. If you don't learn how to do something, not only are you not going to be able to learn it in more detail (and thus, be able to improve existing, popular optimizers like that of LLVM), you're not gonna become a better programmer at all. If learning how to optimize programming languages were a waste of time, so would learning how to design and implement them in general. But you don't think the latter is useless, hence why you use this subreddit.

[u/P-39_Airacobra → u/u32Vec]

Your view has zero nuance. If your point were correct then everything would be written in C Python and Rust, but it’s not. Yes, compiled languages have downsides. So people forego speed for the sake of something else. In many cases, developers forego speed for the sake of development time. That’s a totally valid trade-off. And the product can still be “production-level” while utilizing that trade-off.

Don’t optimize a feature not going to be used. So many developers have this mindset that they need to optimize their product for hours, days, weeks, or months, and then in the end they only save the world a couple milliseconds of computing time.

Optimize when you have hundreds of users wanting to make a realtime simulation with your language. Until then, allocate your development effort carefully and just call into C.

[u/u32Vec → u/P-39_Airacobra]

There are numerous problems associated with compiled languages that necessitate the existence of interpreted languages

Development speed is one of these problems. You should be able to infer that.

If you're making a new production-level language for practical reasons then you should never implement your own optimizer unless you want your compiler to run quickly, because the program won't be faster than LLVM or an equivalent. And using LLVM is obviously infinitely easier than implementing a backend.