Update cache and clear the cache in non-const func

Author: Chengjunp

llvm/include/llvm/ADT/GenericCycleImpl.h

@@ -47,8 +47,8 @@ bool GenericCycle<ContextT>::contains(const GenericCycle *C) const {
 template <typename ContextT>
 void GenericCycle<ContextT>::getExitBlocks(
     SmallVectorImpl<BlockT *> &TmpStorage) const {
-  if (!ExitBlocksCache->empty()) {
-    TmpStorage = *ExitBlocksCache;
+  if (!ExitBlocksCache.empty()) {
+    TmpStorage = ExitBlocksCache;
     return;
   }
 
@@ -70,7 +70,7 @@ void GenericCycle<ContextT>::getExitBlocks(
 
     TmpStorage.resize(NumExitBlocks);
   }
-  ExitBlocksCache->append(TmpStorage.begin(), TmpStorage.end());
+  ExitBlocksCache.append(TmpStorage.begin(), TmpStorage.end());
 }
 
 template <typename ContextT>
@@ -304,6 +304,8 @@ void GenericCycleInfo<ContextT>::moveTopLevelCycleToNewParent(CycleT *NewParent,
   for (auto &It : BlockMapTopLevel)
     if (It.second == Child)
       It.second = NewParent;
+  NewParent->clearCache();
+  Child->clearCache();
 }
 
 template <typename ContextT>
@@ -322,6 +324,7 @@ void GenericCycleInfo<ContextT>::addBlockToCycle(BlockT *Block, CycleT *Cycle) {
   }
 
   BlockMapTopLevel.try_emplace(Block, Cycle);
+  Cycle->clearCache();
 }
 
 /// \brief Main function of the cycle info computations.

llvm/include/llvm/ADT/GenericCycleInfo.h

@@ -75,28 +75,34 @@ template <typename ContextT> class GenericCycle {
   unsigned Depth = 0;
 
   /// Cache for the results of GetExitBlocks
-  std::unique_ptr<SmallVector<BlockT *, 4>> ExitBlocksCache;
+  mutable SmallVector<BlockT *, 4> ExitBlocksCache;
 
   void clear() {
     Entries.clear();
     Children.clear();
     Blocks.clear();
     Depth = 0;
     ParentCycle = nullptr;
-    ExitBlocksCache->clear();
+    clearCache();
   }
 
-  void appendEntry(BlockT *Block) { Entries.push_back(Block); }
-  void appendBlock(BlockT *Block) { Blocks.insert(Block); }
+  void appendEntry(BlockT *Block) {
+    Entries.push_back(Block);
+    clearCache();
+  }
+
+  void appendBlock(BlockT *Block) {
+    Blocks.insert(Block);
+    clearCache();
+  }
 
   GenericCycle(const GenericCycle &) = delete;
   GenericCycle &operator=(const GenericCycle &) = delete;
   GenericCycle(GenericCycle &&Rhs) = delete;
   GenericCycle &operator=(GenericCycle &&Rhs) = delete;
 
 public:
-  GenericCycle()
-      : ExitBlocksCache(std::make_unique<SmallVector<BlockT *, 4>>()) {};
+  GenericCycle() = default;
 
   /// \brief Whether the cycle is a natural loop.
   bool isReducible() const { return Entries.size() == 1; }
@@ -107,6 +113,13 @@ template <typename ContextT> class GenericCycle {
     return Entries;
   }
 
+  /// Clear the cache of the cycle.
+  /// This should be run in all non-const function in GenericCycle
+  /// and GenericCycleInfo.
+  void clearCache() const {
+    ExitBlocksCache.clear();
+  }
+
   /// \brief Return whether \p Block is an entry block of the cycle.
   bool isEntry(const BlockT *Block) const {
     return is_contained(Entries, Block);
@@ -117,6 +130,7 @@ template <typename ContextT> class GenericCycle {
     assert(contains(Block));
     Entries.clear();
     Entries.push_back(Block);
+    clearCache();
   }
 
   /// \brief Return whether \p Block is contained in the cycle.
@@ -129,7 +143,12 @@ template <typename ContextT> class GenericCycle {
   bool contains(const GenericCycle *C) const;
 
   const GenericCycle *getParentCycle() const { return ParentCycle; }
-  GenericCycle *getParentCycle() { return ParentCycle; }
+
+  GenericCycle *getParentCycle() {
+    clearCache();
+    return ParentCycle;
+  }
+
   unsigned getDepth() const { return Depth; }
 
   /// Return all of the successor blocks of this cycle.