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Benchmarking GPT-5 on 400 real-world code reviews

qodo.ai

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Re: Benchmarking GPT-5 on 400 real-world code reviews

#71
post #32

Earlier quoted context omitted.

No, they aren't. Most benchmarks use ground truth, not evaluation by another LLM. Using another LLM as verifier, aside from the obvious "quis custodiet custodes ipsos", opens an entire can of worms, such as the fact that there could be systematic biases in the evaluation. This is not in and of itself disqualifying but it should be addressed, and the article doesn't even say anything.

Ground truth evaluation is not that simple unless you are doing multiple-choice-style tests or something similar where the correctness of an answer can be determined by a simple process. Open ended natural language tasks like this one are incredibly difficult to evaluate and using LLMs as judge is not just the current standard, it is basically the only way to do it at scale economically.

The original comment was this:

> So there's no ground truth; they're just benchmarking how impressive an LLM's code review sounds to a different LLM. Hard to tell what to make of that.

The comment I replied to was:

> That's how 99% of 'LLM benchmark numbers' circulating on the internet work.

And that's just false. SWE-Bench verified isn't like this. Aider Polyglot isn't like this. SWE-Lancer Diamond isn't like this. The new internal benchmarks used by OpenAI in GPT-5's model card aren't like this.

Maybe this benchmark is a special snowflake and needs LLM-as-a-judge, but this doesn't invalidate the original concern: setting up a benchmark this way runs into a series of problems and is prone to show performance differences that might not be there with a different setups. Benchmarks are already hard to trust, I'm not sure how this is any more indicative than the rest.

Re: Benchmarking GPT-5 on 400 real-world code reviews

#72
post #32

Earlier quoted context omitted.

That's how 99% of 'LLM benchmark numbers' circulating on the internet work.

No, they aren't. Most benchmarks use ground truth, not evaluation by another LLM. Using another LLM as verifier, aside from the obvious "quis custodiet custodes ipsos", opens an entire can of worms, such as the fact that there could be systematic biases in the evaluation. This is not in and of itself disqualifying but it should be addressed, and the article doesn't even say anything.

Even the benchmarks for maths only checked numerical answers for ground truth, which means the LLM can output a lot of nonsense and guess the correct answer to pass it

Re: Benchmarking GPT-5 on 400 real-world code reviews

#73
post #12
post #4

> Each model’s responses are ranked by a high-performing judge model — typically OpenAI’s o3 — which compares outputs for quality, relevance, and clarity. These rankings are then aggregated to produce a performance score. So there's no ground truth; they're just benchmarking how impressive an LLM's code review sounds to a different LLM. Hard to tell what to make of that.

Why is it hard to ignore an attempt to assess reality that is not grounded in reality?

That's an extremely dense question :) (Not pejorative, but conceptual dense).

I had some fun trying to answer it, ignoring fixating on whether or not the premise is true, for argument's sake.

My answer is:

I would think "attempting to assess reality that is not grounded in reality" is hard to ignore due to a combination of "it's what is available," being easy to understand, and seeming useful (decoupled from whether it's really so). As a result, it's hard to ignore because it's what is mostly available to us for consumption and is easy to make "consumable."

I think there is a LARGE overlap in this topic with my pet peeve and hatred of mock tests in development. They are not completely useless, but their obvious flaws and vulnerabilities seem to me to be in the same area: "Not grounded in reality."

Said another way: Because it's what's easy to make, and thus there is a lot of it, creating a positive feedback loop of mere-exposure effect. Then it becomes hard to ignore because it's what's shoved in our face.

Re: Benchmarking GPT-5 on 400 real-world code reviews

#74

> the “minimal” GPT-5 variant ... achieved a score of 58.5 the image shows it with a score of 62.7, not 58.5 which is right? mistakes like this undermine the legitimacy of a closed benchmark, especially one judged by an LLM

A large chunk of this article reads like LLM generated, so I guess it was never proofread, and details like this are not validated, or they could be entirely made up i.e. hallucinated.

Re: Benchmarking GPT-5 on 400 real-world code reviews

#75
> GPT-5 stood out for its analytical strength and review clarity.

The sentence is too obviously LLM generated, but whatever.

> Weaknesses:

>

> False positives: A few reviews include incorrect or harmful fixes.

> Inconsistent labeling: Occasionally misclassifies the severity of findings or touches forbidden lines.

> Redundancy: Some repetition or trivial suggestions that dilute review utility.

wtf are "forbidden lines"?

Re: Benchmarking GPT-5 on 400 real-world code reviews

#78

> the “minimal” GPT-5 variant ... achieved a score of 58.5 the image shows it with a score of 62.7, not 58.5 which is right? mistakes like this undermine the legitimacy of a closed benchmark, especially one judged by an LLM

Probably written by an llm too…

Re: Benchmarking GPT-5 on 400 real-world code reviews

#79

Earlier quoted context omitted.

At the heart of the P vs NP problem lies the observation that solution verification seems to be much easier than solution generation. If that applies in this context is another question but I think it is not unreasonable to assume that the judge needs to be less powerful than the performer. Or in other words, I don't need to be a chef myself to decide if a meal is good or not.

That really doesn't hold for all problems. You can imagine any number of problems where a valid solution is easier, complexity wise, to generate than it is to validate. A trivial example is semiprime factorization. Easy to generate any semiprime, hard to factor.

> That really doesn't hold for all problems.

But it does hold for this problem.

Re: Benchmarking GPT-5 on 400 real-world code reviews

#80

Earlier quoted context omitted.

Am I missing something? If LLM-1 is supposed to judge LLM-2, doesn't LLM-1 have to be better than LLM-2? If LLM-1 is only 40% as good at coding as LLM-2, why would you trust the LLM with the lesser knowledge?

At the heart of the P vs NP problem lies the observation that solution verification seems to be much easier than solution generation. If that applies in this context is another question but I think it is not unreasonable to assume that the judge needs to be less powerful than the performer. Or in other words, I don't need to be a chef myself to decide if a meal is good or not.

It's a bit different for reasoning LLMs - they operate in a feedback loop, measuring the quality of the solution and iterating on it until either the quality meets a desired threshold, or all reasoning effort is expended.

This can correct for generation errors, but cannot correct for quality measurement errors, so the question is valid.

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