[llvm] [CycleInfo] Represent cycles by an opaque handle. NFC (PR #210117)

[Alexis Engelke via llvm-commits]

================
@@ -47,7 +46,7 @@ class LLVM_ABI MachineCycleInfoWrapperPass : public MachineFunctionPass {
 // TODO: add this function to the GenericCycleInfo template after implementing
 //       the IR version.
 LLVM_ABI bool isCycleInvariant(const MachineCycleInfo &CI,
-                               const MachineCycle &Cycle, MachineInstr &I);
+                               const CycleRef &Cycle, MachineInstr &I);
----------------
aengelke wrote:

CycleRef Cycle?

https://github.com/llvm/llvm-project/pull/210117