We’ve created GPT-4, the latest milestone in OpenAI’s effort in scaling up deep learning. GPT-4 is a large multimodal model (accepting image and text inputs, emitting text outputs) that, while worse than humans in many real-world scenarios, exhibits human-level performance on various professional and academic benchmarks.
Full paper available here: https://cdn.openai.com/papers/gpt-4.pdf
RSI doesn't require a self authored codebase anyways. RSI can be as simple as "edit a text file to control an existing framework", where that framework is authored by humans (who used gpt-4 or codex to accelerate authoring it)