From 5e10e21d28496ba40ccd385740d7d1b4bb1368e4 Mon Sep 17 00:00:00 2001
From: Chandler Carruth <chandlerc@gmail.com>
Date: Wed, 14 Jan 2015 10:07:19 +0000
Subject: [PATCH] [PM] Make DominatorTrees (corectly) movable so that we can
 move them into the new pass manager's analysis cache which stores results
 by-value.

Technically speaking, the dom trees were originally not movable but
copyable! This, unsurprisingly, didn't work at all -- the copy was
shallow and just resulted in rampant memory corruption. This change
explicitly forbids copying (as it would need to be a deep copy) and
makes them explicitly movable with the unsurprising boiler plate to
member-wise move them because we can't rely on MSVC to generate this
code for us. =/

llvm-svn: 225966
---
 llvm/include/llvm/IR/Dominators.h          |  7 ++++
 llvm/include/llvm/Support/GenericDomTree.h | 52 +++++++++++++++++++++++++++++-
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/llvm/include/llvm/IR/Dominators.h b/llvm/include/llvm/IR/Dominators.h
index e2d1ccc..4e7dacc 100644
--- a/llvm/include/llvm/IR/Dominators.h
+++ b/llvm/include/llvm/IR/Dominators.h
@@ -69,6 +69,13 @@ public:
 
   DominatorTree() : DominatorTreeBase<BasicBlock>(false) {}
 
+  DominatorTree(DominatorTree &&Arg)
+      : Base(std::move(static_cast<Base &>(Arg))) {}
+  DominatorTree &operator=(DominatorTree &&RHS) {
+    Base::operator=(std::move(static_cast<Base &>(RHS)));
+    return *this;
+  }
+
   /// \brief Returns *false* if the other dominator tree matches this dominator
   /// tree.
   inline bool compare(const DominatorTree &Other) const {
diff --git a/llvm/include/llvm/Support/GenericDomTree.h b/llvm/include/llvm/Support/GenericDomTree.h
index 7640bf8..fa56f9a 100644
--- a/llvm/include/llvm/Support/GenericDomTree.h
+++ b/llvm/include/llvm/Support/GenericDomTree.h
@@ -34,9 +34,20 @@ namespace llvm {
 template <class NodeT> class DominatorBase {
 protected:
   std::vector<NodeT *> Roots;
-  const bool IsPostDominators;
+  bool IsPostDominators;
   explicit DominatorBase(bool isPostDom)
       : Roots(), IsPostDominators(isPostDom) {}
+  DominatorBase(DominatorBase &&Arg)
+      : Roots(std::move(Arg.Roots)),
+        IsPostDominators(std::move(Arg.IsPostDominators)) {
+    Arg.Roots.clear();
+  }
+  DominatorBase &operator=(DominatorBase &&RHS) {
+    Roots = std::move(RHS.Roots);
+    IsPostDominators = std::move(RHS.IsPostDominators);
+    RHS.Roots.clear();
+    return *this;
+  }
 
 public:
   /// getRoots - Return the root blocks of the current CFG.  This may include
@@ -171,6 +182,9 @@ void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType> &DT,
 /// This class is a generic template over graph nodes. It is instantiated for
 /// various graphs in the LLVM IR or in the code generator.
 template <class NodeT> class DominatorTreeBase : public DominatorBase<NodeT> {
+  DominatorTreeBase(const DominatorTreeBase &) LLVM_DELETED_FUNCTION;
+  DominatorTreeBase &operator=(const DominatorTreeBase &) LLVM_DELETED_FUNCTION;
+
   bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
                                const DomTreeNodeBase<NodeT> *B) const {
     assert(A != B);
@@ -183,6 +197,18 @@ template <class NodeT> class DominatorTreeBase : public DominatorBase<NodeT> {
     return IDom != nullptr;
   }
 
+  /// \brief Wipe this tree's state without releasing any resources.
+  ///
+  /// This is essentially a post-move helper only. It leaves the object in an
+  /// assignable and destroyable state, but otherwise invalid.
+  void wipe() {
+    DomTreeNodes.clear();
+    IDoms.clear();
+    Vertex.clear();
+    Info.clear();
+    RootNode = nullptr;
+  }
+
 protected:
   typedef DenseMap<NodeT *, DomTreeNodeBase<NodeT> *> DomTreeNodeMapType;
   DomTreeNodeMapType DomTreeNodes;
@@ -290,6 +316,30 @@ public:
       : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {}
   virtual ~DominatorTreeBase() { reset(); }
 
+  DominatorTreeBase(DominatorTreeBase &&Arg)
+      : DominatorBase<NodeT>(
+            std::move(static_cast<DominatorBase<NodeT> &>(Arg))),
+        DomTreeNodes(std::move(Arg.DomTreeNodes)),
+        RootNode(std::move(Arg.RootNode)),
+        DFSInfoValid(std::move(Arg.DFSInfoValid)),
+        SlowQueries(std::move(Arg.SlowQueries)), IDoms(std::move(Arg.IDoms)),
+        Vertex(std::move(Arg.Vertex)), Info(std::move(Arg.Info)) {
+    Arg.wipe();
+  }
+  DominatorTreeBase &operator=(DominatorTreeBase &&RHS) {
+    DominatorBase<NodeT>::operator=(
+        std::move(static_cast<DominatorBase<NodeT> &>(RHS)));
+    DomTreeNodes = std::move(RHS.DomTreeNodes);
+    RootNode = std::move(RHS.RootNode);
+    DFSInfoValid = std::move(RHS.DFSInfoValid);
+    SlowQueries = std::move(RHS.SlowQueries);
+    IDoms = std::move(RHS.IDoms);
+    Vertex = std::move(RHS.Vertex);
+    Info = std::move(RHS.Info);
+    RHS.wipe();
+    return *this;
+  }
+
   /// compare - Return false if the other dominator tree base matches this
   /// dominator tree base. Otherwise return true.
   bool compare(const DominatorTreeBase &Other) const {
-- 
2.7.4