Can you look at code today and predict what assembly a compiler will output to some high degree of accuracy? Do you avoid certain classes of compiler optimization so you can more accurately predict compiler output? I recall a time where many compilers would remove a bzero() operation in situations where you’re trying to zero out a buffer that had sensitive data in it - it’s why we have APIs like https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src.... I ran into a huge performance regression because I didn’t have all the edges of named return value optimization in mind when I refactored some code.

There’s ambiguity in the x86 specification, such that you can execute a single instruction and get different results in intel vs amd. See the rcpss instruction, for example.

I get that LLMs are categorically different, and they’re absolutely not as reliable as compilers are, but compilers are also not as reliable as compilers seem. And even less predictable IMO.