There are some llvm based shader compilers out there. Some even open (AMD), some not (Nvidia). The situation with architectures in 90s sounds about right: Thos

There are some llvm based shader compilers out there. Some even open (AMD), some not (Nvidia). The situation with architectures in 90s sounds about right: Those that were kept closed (and where a gcc backend was thus no option for the vendor - mostly embedded stuff) have to this day shitty compilers with unpredictable optimizers.