[llvm] [CodeGen] Utilizing register units based liveIns tracking in MBB (PR #129847)

[Vikash Gupta via llvm-commits]

vg0204 wrote:

Could one solution be : We can store only the live regunits (for either of its root) as MCPhysReg in LiveInList using the its attached laneBitMask value provided (or entire Reg in case laneBitmask is set as All), rather than storing the laneBitMask as part of the LiveIn. For Example :

`liveins: $vgpr0_vgpr1:0x00003, $vgpr4, $vgpr5:0x000001`

will be transformed into :

`liveins: $vgpr0_lo16, $vgpr0_hi16, $vgpr4, $vgpr5_hi16`

Does it make sense?

https://github.com/llvm/llvm-project/pull/129847