[llvm] [FixIrreducible] Use CycleInfo instead of a custom SCC traversal (PR #101386)

[Sameer Sahasrabuddhe via llvm-commits]

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@@ -107,6 +107,12 @@ template <typename ContextT> class GenericCycle {
     return is_contained(Entries, Block);
   }
 
+  /// \brief Replace all entries with \p Block as single entry.
+  void setSingleEntry(BlockT *Block) {
+    Entries.clear();
+    Entries.push_back(Block);
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ssahasra wrote:

Good catch! Replaced it with a stronger test to check that `Block` is contained in the current cycle.

https://github.com/llvm/llvm-project/pull/101386