[llvm] [AMDGPU] misched: avoid subregister dependencies (PR #140255)

[Robert Imschweiler via llvm-commits]

================
@@ -545,6 +677,16 @@ void GCNSubtarget::adjustSchedDependency(
   MachineInstr *DefI = Def->getInstr();
   MachineInstr *UseI = Use->getInstr();
 
+  if (const auto &[IsRealDep, Reg] =
----------------
ro-i wrote:

Initially, I wanted three return states: no real dependency, real dependency with modified reg, and real dependency without modified reg (because I wasn't sure if I should rather return DefReg or UseReg). But it's better the way you suggested

https://github.com/llvm/llvm-project/pull/140255