[llvm] [AMDGPU] Fix undefined scc register in successor block of SI_KILL terminators (PR #134718)

[Juan Manuel Martinez Caamaño via llvm-commits]

================
@@ -4516,6 +4516,38 @@ SITargetLowering::splitKillBlock(MachineInstr &MI,
   MachineBasicBlock *SplitBB = BB->splitAt(MI, false /*UpdateLiveIns*/);
----------------
jmmartinez wrote:

What if we set `UpdateLiveIns` to true ? Wouldn't that cover the case we're trying to cover here ?

https://github.com/llvm/llvm-project/pull/134718