DomTree: Remove the releaseMemory() method

[nhaehnle]

Summary

It is fully redundant with reset().

Change-Id: I25850b9f08eace757cf03cbb8780e970aca7f51a

[dblaikie]

@arsenm - if you can, please include some text whenever approving a patch via phabricator, otherwise no email indicating approval is sent to the mailing lists (which makes auditing reviews difficult)

clang/include/clang/Analysis/Analyses/Dominators.h

public:
   }
 
   /// Tests whether \p A is reachable from the entry block.
   bool isReachableFromEntry(const CFGBlock *A) {
     return DT.isReachableFromEntry(A);
   }
 
   /// Releases the memory held by the dominator tree.
-  virtual void releaseMemory() {
-    DT.releaseMemory();
-  }
+  virtual void releaseMemory() { DT.reset(); }
 
   /// Converts the dominator tree to human readable form.
   virtual void print(raw_ostream &OS, const llvm::Module* M= nullptr) const {
     DT.print(OS);
   }
 
 private:
   CFG *cfg;

llvm/include/llvm/Analysis/PostDominators.h

struct PostDominatorTreeWrapperPass : public FunctionPass {
   bool runOnFunction(Function &F) override;
 
   void verifyAnalysis() const override;
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesAll();
   }
 
-  void releaseMemory() override {
-    DT.releaseMemory();
-  }
+  void releaseMemory() override { DT.reset(); }
 
   void print(raw_ostream &OS, const Module*) const override;
 };
 
 FunctionPass* createPostDomTree();
 
 template <> struct GraphTraits<PostDominatorTree*>
   : public GraphTraits<DomTreeNode*> {

llvm/include/llvm/IR/Dominators.h

public:
   bool runOnFunction(Function &F) override;
 
   void verifyAnalysis() const override;
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesAll();
   }
 
-  void releaseMemory() override { DT.releaseMemory(); }
+  void releaseMemory() override { DT.reset(); }
 
   void print(raw_ostream &OS, const Module *M = nullptr) const override;
 };
 } // end namespace llvm
 
 #endif // LLVM_IR_DOMINATORS_H

llvm/include/llvm/Support/GenericDomTree.h

for (const auto &DomTreeNode : DomTreeNodes) {
 
       if (MyNd.compare(&OtherNd))
         return true;
     }
 
     return false;
   }
 
-  void releaseMemory() { reset(); }
-
   /// getNode - return the (Post)DominatorTree node for the specified basic
   /// block.  This is the same as using operator[] on this class.  The result
   /// may (but is not required to) be null for a forward (backwards)
   /// statically unreachable block.
   DomTreeNodeBase<NodeT> *getNode(const NodeT *BB) const {
     auto I = DomTreeNodes.find(BB);
     if (I != DomTreeNodes.end())
       return I->second.get();
public:
   ///  - Fast  -- checks basic tree structure and compares it with a freshly
   ///             constructed tree.
   ///             Takes O(N^2) time worst case, but is faster in practise (same
   ///             as tree construction).
   bool verify(VerificationLevel VL = VerificationLevel::Full) const {
     return DomTreeBuilder::Verify(*this, VL);
   }
 
-protected:
-  void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
-
   void reset() {
     DomTreeNodes.clear();
     Roots.clear();
     RootNode = nullptr;
     Parent = nullptr;
     DFSInfoValid = false;
     SlowQueries = 0;
   }
 
+protected:
+  void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
+
   // NewBB is split and now it has one successor. Update dominator tree to
   // reflect this change.
   template <class N>
   void Split(typename GraphTraits<N>::NodeRef NewBB) {
     using GraphT = GraphTraits<N>;
     using NodeRef = typename GraphT::NodeRef;
     assert(std::distance(GraphT::child_begin(NewBB),
                          GraphT::child_end(NewBB)) == 1 &&