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Claude’s C Compiler vs. GCC

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Re: Claude’s C Compiler vs. GCC

#231

Post by delaminator »

bgirard wrote: post #30
marcus_holmes wrote: post #8

I think this is a great example of both points of view in the ongoing debate. Pro-LLM coding agents: look! a working compiler built in a few hours by an agent! this is amazing! Anti-LLM coding agents: it's not a working compiler, though. And it doesn't matter how few hours it took, because it doesn't work. It's useless. Pro: Sure, but we can get the agent to fix that. Anti: Can you, though? We've seen that the more c…

This to me sounds a lot like the SpaceX conversation: - Ohh look it can [write small function / do a small rocket hop] but it can't [ write a compiler / get to orbit]! - Ohh look it can [write a toy compiler / get to orbit] but it can't [compile linux / be reusable] - Ohh look it can [compile linux / get reusable orbital rocket] but it can't [build a compiler that rivals GCC / turn the rockets around fast enough] - T…

In 1908 the Model T could do 45mph.

In 1935 the Auburn 851 S/C Speedster hit 100mph

In 1955 the Mercedes-Benz 300 SL Gullwing did 161mph

In 2025 the Yangwang U9 Xtreme hit 308mph

progress is a decaying exponential - Tsiolkovsky's tyranny

Re: Claude’s C Compiler vs. GCC

#232

Post by troupo »

codebolt wrote: post #215
troupo wrote: post #206

Earlier quoted context omitted.

"It's just another Markdown file, bro". LLMs do not learn. So every new session for them will be rebuilding the world from scratch. Bloated Markdown files quickly exhaust context windows, and agents routinely ignore large parts of them. And then you unleash them on one code base that's more than a couple of days old, and they happily duplicate code, ignore existing code paths, ignore existing conventions etc.

That's why I'm very careful about how the context is constructed. I make sure all the relevant files are loaded with the prompt, including the project file so it can see the directory structure. Also keep a brief summary of the app functionality and architecture in the AGENTS.md file. For larger tasks, always request a plan and look through it before asking it to start writing code.

Yup, we've become reverse centaurs :) https://doctorow.medium.com/https-pluralistic-net-2025-09-11...

Re: Claude’s C Compiler vs. GCC

#233

Post by vasco »

kleiba wrote: post #173
vasco wrote: post #125

Earlier quoted context omitted.

He is not polite, he is of the utmost rudeness. As a reply to being pointed to the fact that he copied so much code that the generated code included someone else's name in the License, his reply was https://github.com/ocaml/ocaml/pull/14369/changes/ce372a60bd... I struggle to think how someone thinks this is polite. Is politeness to you just not using curse words?

Admittedly, his handling of this aspect was perhaps less than ideal, but I cannot see any impoliteness here whatsoever. As a matter of fact, I struggle to think how you could think otherwise. But I am biased. After having lived a number of years in a country where I would say the average understanding of politeness is vastly different from where I've grown up, I've learned that there is just a difference of opinion o…

You sound like you'd characterize a thief as polite if he asked you please when taking your wallet.

Re: Claude’s C Compiler vs. GCC

#234

Post by yc-kraln »

It's really difficult for me to understand the level of cynicism in the HN comments on this topic, at all. The amount of goalpost-moving and redefining is absolutely absurd. I really get the impression that the majority of the HN comments are just people whining about sour grapes, with very little value added to the discussion.

I'd like to see someone disagree with the following:

Building a C compiler, targeting three architectures, is hard. Building a C compiler which can correctly compile (maybe not link) the modern linux kernel is damn hard. Building a C compiler which can correctly compile sqlite and pass the test suite at any speed is damn hard.

To the specific issues with the concrete project as presented: This was the equivalent of a "weekend project", and it's amazing

So what if some gcc is needed for the 16-bit stuff? So what if a human was required to steer claude a bit? So what if the optimizing pass practically doesn't exist?

Most companies are not software companies, software is a line-item, an expensive, an unavoidable cost. The amount of code (not software engineering, or architecture, but programming) developed tends towards glue of existing libraries to accomplish business goals, which, in comparison with a correct modern C compiler, is far less performance critical, complex, broad, etc. No one is seriously saying that you have to use an LLM to build your high-performance math library, or that you have to use an LLM to build anything, much in the same way that no one is seriously saying that you have to rewrite the world in rust, or typescript, or react, or whatever is bothering you at the moment.

I'm reminded of a classic slashdot comment--about attempting to solve a non-technical problem with technology, which is doomed to fail--it really seems that the complaints here aren't about the LLMs themselves, or the agents, but about what people/organizations do with them, which is then a complaint about people, but not the technology.

Re: Claude’s C Compiler vs. GCC

#235

Post by Ygg2 »

NitpickLawyer wrote: post #225
Ygg2 wrote: post #115

Earlier quoted context omitted.

> It's a system based on LLMs. What you said is: > First, remember when we had LLMs run optimisation passes last year? Alphaevolve doing square packing If I start a sentence: First, remember the fish intelligence competition last year? Rossie jumped through a hula hoop. I, and other readers (probably), would think Rossie is a fish. Not a dog. Even if you can technically group dogs as a sort of fish descendant.

I have no idea what you're arguing. Alphaevolve is similar to claude code. They are using LLMs in a harness. No idea what you mean with fish, kidneys and so on. Can you please stick to the technical stuff? Otherwise it's just noise.

I'm arguing your writing is unclear and confusing. You can't continue a sentence and pretend the new sentence isn't related to the previous one.

Alpha Evolve is made from LLMs, but it's not the only part. If anything, it needs a genetic algo component. LLMs generally don't evolve.

Also, why are you focusing on AlphaEvolve? I made two other points you haven't addressed.

Re: Claude’s C Compiler vs. GCC

#236

Post by lelanthran »

iv11 wrote: post #56

I wonder how well an LLM would do for a new CPU architecture for which no C compiler exists yet, just assembler.

> I wonder how well an LLM would do for a new CPU architecture for which no C compiler exists yet, just assembler.

Quite well, possibly.

Look, I wasn't even aware of this until it popped up a few days ago on HN, I am not privy to the details of Anthropics engineers in general, or the specific engineer who curated this marathon multi-agent dev cycle, but I can tell you how anyone familiar with compilers or programming language development will proceed:

1. Vibe an IL (intermediate language) specification into existence (even if it is only held in RAM as structures/objects)

2. Vibe some utility functions for the IL (dump, search, etc)

3. Vibe a set of backends, that take IL as input and emit ISA (Instruction Set Architecture), with a set of tests for each target ISA

4. Vibe a front-end that takes C language input and outputs the IL, with a set of tests for each language construct.

(Everything from #2 onwards can be done in parallel)

I have no reason to believe that the engineer who vibe-coded CCC is anything other than competent and skillful, so lets assume he did at least the above (TBH, he probably did more)[1].

This means that CCC has, in its code, everything needed to vibe a never-before-seen ISA, given the ISA spec. It also means it has everything needed to support a new front-end language as long as it is similar enough to C (i.e. language constructs can map to the IL constructs).

So, this should be pretty easy to expand on, because I find it unlikely that the engineer who supervised/curated the process would be anything less than an expert.

The only flaw in my argument is that I am assuming that effort from CC was so large because it did the src -> IL -> ISA route. If my assumption is wrong, it might be well-nigh impossible to add support for a new ISA.

------------------------------

[1] When I agreed to a previous poster on a previous thread that I can recreate the functionality of CCC for $20k, these are the steps I would have followed, except I would not have LLM-generated anything.

Re: Claude’s C Compiler vs. GCC

#237

Post by zozbot234 »

marcus_holmes wrote: post #8

I think this is a great example of both points of view in the ongoing debate. Pro-LLM coding agents: look! a working compiler built in a few hours by an agent! this is amazing! Anti-LLM coding agents: it's not a working compiler, though. And it doesn't matter how few hours it took, because it doesn't work. It's useless. Pro: Sure, but we can get the agent to fix that. Anti: Can you, though? We've seen that the more c…

You didn't even mention that this vibe-coded toy compiler cost $20k in token spend. That's an insane amount of money for what this is.

Re: Claude’s C Compiler vs. GCC

#238

Post by [deleted] »

tyre wrote: post #78

As a neutral observation: it’s remarkable how quickly we as humans adjust expectations. Imagine five years ago saying that you could have a general purpose AI write a c compiler that can handle the Linux kernel, by itself, from scratch for $20k by writing a simple English prompt. That would have been completely unbelievable! Absurd! No one would take it seriously. And now look at where we are.

[deleted]

Re: Claude’s C Compiler vs. GCC

#239

Post by player1234 »

tyre wrote: post #78

As a neutral observation: it’s remarkable how quickly we as humans adjust expectations. Imagine five years ago saying that you could have a general purpose AI write a c compiler that can handle the Linux kernel, by itself, from scratch for $20k by writing a simple English prompt. That would have been completely unbelievable! Absurd! No one would take it seriously. And now look at where we are.

[dead]

Re: Claude’s C Compiler vs. GCC

#240

Post by NitpickLawyer »

Ygg2 wrote: post #235
NitpickLawyer wrote: post #225

Earlier quoted context omitted.

I have no idea what you're arguing. Alphaevolve is similar to claude code. They are using LLMs in a harness. No idea what you mean with fish, kidneys and so on. Can you please stick to the technical stuff? Otherwise it's just noise.

I'm arguing your writing is unclear and confusing. You can't continue a sentence and pretend the new sentence isn't related to the previous one. Alpha Evolve is made from LLMs, but it's not the only part. If anything, it needs a genetic algo component. LLMs generally don't evolve. Also, why are you focusing on AlphaEvolve? I made two other points you haven't addressed.

You have no idea what alphaevolve is, yet you try to correct me. This isn't productive, I'm out.
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