There are over 10 different x86 CPUs, some with very dodgy implementation of basic x86, not mentioning extensions. It could have been just a typical "safe" corp

There are over 10 different x86 CPUs, some with very dodgy implementation of basic x86, not mentioning extensions. It could have been just a typical "safe" corporate decision to run optimized code path only on specific Intel CPUs. They use different code paths for different Intel CPUs/generations as well. Now imagine they had to believe that Hygon/SiS/Vortex implement it properly... It's not completely black/white.