I'm not sure which discussion you're referring to; I've seen the topic come up many times. But I haven't seen a reasonably non-evil explanation for why the compiler should preemptively assume that AMD's CPU feature flags cannot be trusted, while Intel's can. Detecting known-buggy CPU models is fine, but assuming that future AMD CPUs are more likely to introduce bugs to AVX-whatever than future Intel CPUs is not something that I have seen justified.