[llvm] [AMDGPU] Add IR LiveReg type-based optimization (PR #66838)

[Jeffrey Byrnes via llvm-commits]

================
@@ -1982,5 +350,56 @@ bb.2:
   ret void
 }
 
-declare i32 @llvm.amdgcn.workitem.id.x()
+define amdgpu_kernel void @repeat_successor(i32 %in, ptr addrspace(1) %src1, ptr addrspace(1) %src2, ptr addrspace(1) nocapture %dst) {
----------------
jrbyrnes wrote:

@arsenm Is this what you meant by "predecessor block has a repeated successor" test?

https://github.com/llvm/llvm-project/pull/66838