[llvm] [AMDGPU] Allow hoisting of V_READFIRSTLANE_B32 for uniform operand (PR #178312)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

> In that respect, I think the new approach is safer.

I think I do object this 'safer'. This is safe, so far I have not seen a counter example.

https://github.com/llvm/llvm-project/pull/178312