AMD investing in Linux build systems to ensure that every library shipped on every Linux distro runs optimally on their processors would do a huge service to them.

From time to time I check builds and performance on POWER. There is a Brazilian university that provisions POWER9 systems for free (for short times). I am not sure how actively IBM collaborates with glibc, gcc and clang crowd or how dedicated to make Linux workloads perform better on POWER than they do on similarly priced Xeon boxes. I also know Intel has some hard-to-find non-commercial licenses for their compiler and performance analyzers one can use to fine tune their code to Intel architectures (and make it terrible on anything else ;-)) which is perfectly fine if you know what CPUs your code is going to run on (as it frequently is with HPC).