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

[Fangrui Song via llvm-commits]

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@@ -1062,20 +1055,19 @@ const CycleT *getIntDivCycle(const CycleInfoT &CI, const CycleT *Cycle,
 
 template <typename ContextT, typename CycleInfoT, typename CycleT,
           typename BlockT, typename DominatorTreeT>
-const CycleT *
-getOutermostDivergentCycle(const CycleInfoT &CI, const CycleT *Cycle,
-                           const BlockT *DivTermBlock, const BlockT *JoinBlock,
-                           const DominatorTreeT &DT, ContextT &Context) {
+CycleT getOutermostDivergentCycle(const CycleInfoT &CI, CycleT Cycle,
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MaskRay wrote:

The return type `CycleT` refers to `typename CycleT`, which is a GenericCycleRef. The `Cycle -> CycleRef` and de-template will fix the confusion here.

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