[llvm] [AArch64] Define high bits of FPR and GPR registers (take 2) (PR #114827)

[Sander de Smalen via llvm-commits]

sdesmalen-arm wrote:

I'm not entirely sure how llvm-mca works, but I think the issue is that the code adds dependences for all sub-registers of a register, but when `clearsSuperRegisters` evalutes to true it clears dependences for super-registers without considering any of the sibling `_hi` registers. For example; a write to `w0` also clears a dependence on `x0`, but the dependence on artificial register `w0_hi` should also be cleared. It seems easiest not to consider artificial registers in the computation to start with.

https://github.com/llvm/llvm-project/pull/114827