There's no way to say this without sounding mean: Everything Chris Lattner has done has been a "successful mess". He's obviously smart, but a horrible engineer. No one should allow him to design anything.

Edit: I explained my position better below.

▲ pbohun 7 hours ago | parent | next [-]

People are correct I didn't explain my position.

LLVM: Pretty much everyone who has created a programming language with it has complained about its design. gingerbill, Jon Blow, and Andrew Kelley have all complained about it. LLVM is a good idea, but it that idea was executed better by Ken Thompson with his C compiler for Plan 9, and then again with his Go compiler design. Ken decided to create his own "architecture agnostic" assembly, which is very similar to the IR idea with LLVM.

Swift: I was very excited with the first release of Swift. But it ultimately did not have a very focused vision outlined for it. Because of this, it has morphed into a mess. It tries to be everything for everyone, like C++, and winds up being mediocre, and slow to compile to top it off.

Mojo isn't doesn't exist for the public yet. I hope it turns out to be awesome, but I'm just not going to get my hopes up this time.

▲ levodelellis 6 hours ago | parent | next [-]

Yes. I also written a compiler and I also complained about LLVM.

LLVM is

  - Slow to compile
  - Breaks compilers/doesn't have a stable ABI
  - Optimizes poorly (at least, worse than GCC)

Swift I never used but I tried compiling it once and it was the bottom 2 slowest compiler I ever tested. The only thing nearly as bad was kotlin but 1) I don't actually remember which of these are worse 2) Kotlin wasn't meant to be a CLI compiler, it was meant to compile in the background as a language server so it was designed around that

Mojo... I have things I could say... But I'll stick to this. I talked to engineers there and I asked one how they expected any python developers to use the planned borrow checker. The engineer said "Don't worry about it" ie they didn't have a plan. The nicest thing I can say is they didn't bullshit me 100% of the time when I directly asked a question privately. That's the only nice or neutral thing I could say

▲ jervant 6 hours ago | parent | prev [-]

How many languages are using LLVM as its backend vs Go's?

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pbohun 6 hours ago | parent | next [-]

As far as I know, only Go uses Go's back end because it was specifically designed for Go. But the architecture is such that it makes it trivial for Go to cross compile for any OS and architecture. This is something that LLVM cannot do. You have to compile a new compiler for every OS and arch combo you wish to compile to.

You could imagine creating a modified Go assembler that is more generic and not tied to Go's ABI that could accomplish the same effect as LLVM. However, it'd probably be better to create a project like that from scratch, because most of Go's optimizations happen before reaching the assembler stage.

It would probably be best to have the intermediate language that QBE has and transform that into "intermediate assembly" (IA) very similar to Go's assembly. That way the IL stage could contain nearly all the optimization passes, and the IA stage would focus on code generation that would translate to any OS/arch combo.

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nicoburns 6 hours ago | parent [-]

> As far as I know, only Go uses Go's back end because it was specifically designed for Go. But the architecture is such that it makes it trivial for Go to cross compile for any OS and architecture. This is something that LLVM cannot do. You have to compile a new compiler for every OS and arch combo you wish to compile to.

I don't think that's true. Zig have a cross-compiler (that also compiles C and C++) based on LLVM. I believe LLVM (unlike gcc) is inherently a cross-compiler, and it's mostly just shipping header files for every platform that `zig cc` is adding.

	▲	LeFantome 5 hours ago \| parent [-]
		I do not have enough knowledge to say anything bad about LLVM. As an "amateur" compiler writer, it did confuse me a bit though. What I will say is that it seem popular to start with LLVM and then move away from it. Zig is doign that. Rust is heading in the direction perhaps with Cranelift. It feels that, if LLVM had completely nailed its mission, these kinds of projects would be less common. It is also notable that the Dragonegg project to bring GCC languages to LLVM died but we have multiple projects porting Rust to GCC.

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hu3 6 hours ago | parent | prev | next [-]

Go never advertised, designed for, nor supported external usage of their backend.

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6 hours ago | parent | prev [-]

[deleted]

▲ bahmboo 7 hours ago | parent | prev | next [-]

You don't explain or support your position, you are calling Lattner names. That's not helpful to me or anyone else if we are trying to evaluate his work. Swift has millions of users as does Mojo and Modular in general. These are not trivial accomplishments.

	▲	satvikpendem 6 hours ago \| parent [-]
		Mojo and Modular have millions of users?

▲ refulgentis 7 hours ago | parent | prev | next [-]

> Everything Chris Lattner has done has been a "successful mess".

I don't have an emotional reaction to this, i.e. I don't think you're being mean, but it is wrong and reductive, which people usually will concisely, and perhaps reductively, describe as "mean".

Why is it wrong?

LLVM is great.

Chris Lattner left Apple a *decade* ago, & thus has ~0 impact or responsibility on Swift interop with C++ today.

Swift is a fun language to write, hence, why they shoehorned it in, in the first place.

Mojo is fine, but I wouldn't really know how you or I would judge it. For me, I'm not super-opinionated on Python, and it doesn't diverge heavily from it afaik.

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carefree-bob 7 hours ago | parent [-]

Not just LLVM, but Google's TPU seems to be doing fine also. Honestly it's an impressive track record.

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refulgentis 6 hours ago | parent [-]

He had 0 to do with the TPU.

I was hired around Google around the same time, but not nearly as famous :)

AFAICouldT it was a "hire first, figure out what to do later", and it ended up being Swift for TensorFlow. That went ~nowhere, and he left within 2 years.

That's fine and doesn't reflect on him, in general, that's Google for ya. At least that era of Google.

	▲	carefree-bob 6 hours ago \| parent [-]
		Ahh, thanks for the info. Yeah, I heard Google was a bit messy from colleagues who went there.

▲ dismalaf 7 hours ago | parent | prev [-]

That's why there's nothing that comes close to LLVM and MLIR, right?

If he's such a horrible engineer then we should have lots of LLVM replacements, right?

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pbohun 7 hours ago | parent | next [-]

QBE is a tiny project, but I think illustrates a better intermediate language design. https://c9x.me/compile/

	▲	dismalaf 4 hours ago \| parent [-]
		Except performance isn't great and it covers far fewer platforms. It aims for 70% performance but the few benchmarks I've seen show more like 30-50% performance. It's a cool project and I'd consider it for a toy language but it's far from an LLVM replacement.

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levodelellis 5 hours ago | parent | prev [-]

Many compilers including my own uses C89

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dismalaf 4 hours ago | parent [-]

You'll still need a C compiler...

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levodelellis 3 hours ago | parent [-]

I never heard of hardware without one

	▲	dismalaf 3 hours ago \| parent [-]
		Avoiding interacting with LLVM as a user doesn't mean you've created something equivalent to LLVM. And if the C compiler you use is clang then you're still literally making use of LLVM.