These legacy CPUs are known to clang but not llvm.
Their use was ignored by llvm and it would print a
warning saying it did not recognise them.
However because some of them are default CPUs for their
architecture, you would get those warnings even if you didn't
choose a cpu explicitly.
(now those architectures will default to a "generic" CPU)
Information is thin on the ground for these older chips
so this is the best I could find:
Final part of fixing https://bugs.llvm.org/show_bug.cgi?id=50454.