[llvm] [X86][APX] Enable NDD tunings (PR #186049)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon commented:

I'm a bit worried about using tuning flags to control instruction legality through predicates - the instructions are legal just not optimal. Are the perf differences reflected in the scheduler models? Would it be possible to move this to a fixup do you think? I'm hoping to start replacing a few tuning flags with MC patterns e.g. #184016 - and I'm wondering if these will fall into the same category.

https://github.com/llvm/llvm-project/pull/186049