LLVM ist a mess

Posted Mar 20, 2024 22:44 UTC (Wed) by Curan (subscriber, #66186)
In reply to: LLVM ist a mess by khim
Parent article: Cranelift code generation comes to Rust

>> if you need to break core concepts this often, you probably made a lot of mistakes in the past
>
> Nope. Linux kernel breaks internal interfaces pretty often, too. The only problem of LLVM is that it's advertised as something of a separate project while in reality it's only half of many projects.
>
> If all these projects would have lived in one repo and people would have changed everything in sync it wouldn't have even been visible.

I do not care about internal interfaces. I do care about what they break in their official interfaces. Especially in their C interface (which gets worse every release, it seams like, and forces you to use the even worse C++ interface).

And offering a libllvm/libclang means you have to take some responsibility. At least make the minor versions work across the board all the time. Still get the some fails there, when some piece of software bundles their own LLVM and the system has a different one.

>> a lot of LLVM feels like it is a test environment to try out new things for the compiler space
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> Which is precisely what LLVM was designed for. Just open Wikipedia and read: LLVM was originally developed as a research infrastructure to investigate dynamic compilation techniques for static and dynamic programming languages. From what you are saying LLVM works and acts like it was designed to work and act so why is that an issue?

First of all – as others pointed out too – that is not what LLVM claims itself these days. (NB: LLVM/clang is the standard compiler for eg. Mac OS via XCode.) So either there needs to be a big fat warning at the top of all of LLVM that says "don't use my for production, I am a test environment" or LLVM needs to play ball.

>> but then it shouldn't be the basis of anything else
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> Build “better basis for anything else”, isn't that the right solution? Maybe as LLVM fork or write from scratch.
>
> I was told in no-uncertain terms in somewhat tangetially related discussion just over there that you have zero right to complain since LLVM is free.

I have no issue with somebody attempting to build something better (no matter the language or the licensing model). What I do have an issue with is my stuff breaking because of some library. The glibc makes sure my oldest programs still work (even though there will be not much of a chance to get a new version of them for me). I want that commitment from LLVM. I do not care what they do internally. But their interfaces need to be stable enough.

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LLVM ist a mess

Posted Mar 21, 2024 10:06 UTC (Thu) by khim (subscriber, #9252) [Link]

> At least make the minor versions work across the board all the time.

Why should they do that and was there such a promise ever mentioned on their web site?

> Still get the some fails there, when some piece of software bundles their own LLVM and the system has a different one.

Yes, LLVM is designed around the idea that it would be bundled with a frontend. If you have other ideas then it's your responsibility to support them.

> NB: LLVM/clang is the standard compiler for eg. Mac OS via XCode.

Yes. And that pair have stable outer interfaces AFAIK.

> So either there needs to be a big fat warning at the top of all of LLVM that says "don't use my for production, I am a test environment" or LLVM needs to play ball.

It does do that if you use it according to it's design.

For a long time LLVM wasn't even designed to be used as shared library, but at some point Apple decided to change that. And they did. Now it's easier to embed LLVM into external projects as a shared library, but there are still no promises beyond that.

If you want something more than that then it's your responsibility to offer such solution.

> I want that commitment from LLVM. I do not care what they do internally. But their interfaces need to be stable enough.

But who would do the work to ensure that? That's non-trivial amount of work and AFAIK no one ever volunteered.