[llvm-branch-commits] [llvm] [AMDGPU] Make VGPR_16_Lo128 allocatable (PR #173309)

[Shilei Tian via llvm-branch-commits]

https://github.com/shiltian approved this pull request.

What was the reason this RC was not allocatable before?

https://github.com/llvm/llvm-project/pull/173309