Add a ValueMap<ValueOrSubclass*, T> type. ValueMap<Value*, T> is safe to use

even when keys get RAUWed and deleted during its lifetime. By default the keys
act like WeakVHs, but users can pass a third template parameter to configure
how updates work and whether to do anything beyond updating the map on each
action.

It's also possible to automatically acquire a lock around ValueMap updates
triggered by RAUWs and deletes, to support the ExecutionEngine.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84890 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 683 insertions, 0 deletions

diff --git a/docs/ProgrammersManual.html b/docs/ProgrammersManual.html
index 68367de0bf..e4e3dc29c3 100644
--- a/docs/ProgrammersManual.html
+++ b/docs/ProgrammersManual.html
@@ -83,6 +83,7 @@ option</a></li>
       <li><a href="#dss_stringmap">"llvm/ADT/StringMap.h"</a></li>
       <li><a href="#dss_indexedmap">"llvm/ADT/IndexedMap.h"</a></li>
       <li><a href="#dss_densemap">"llvm/ADT/DenseMap.h"</a></li>
+      <li><a href="#dss_valuemap">"llvm/ADT/ValueMap.h"</a></li>
       <li><a href="#dss_map">&lt;map&gt;</a></li>
       <li><a href="#dss_othermap">Other Map-Like Container Options</a></li>
     </ul></li>
@@ -1492,6 +1493,23 @@ inserted into the map) that it needs internally.</p>
 
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection">
+  <a name="dss_valuemap">"llvm/ADT/ValueMap.h"</a>
+</div>
+
+<div class="doc_text">
+
+<p>
+ValueMap is a wrapper around a <a href="#dss_densemap">DenseMap</a> mapping
+Value*s (or subclasses) to another type.  When a Value is deleted or RAUW'ed,
+ValueMap will update itself so the new version of the key is mapped to the same
+value, just as if the key were a WeakVH.  You can configure exactly how this
+happens, and what else happens on these two events, by passing
+a <code>Config</code> parameter to the ValueMap template.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
   <a name="dss_map">&lt;map&gt;</a>
 </div>
 
diff --git a/include/llvm/ADT/ValueMap.h b/include/llvm/ADT/ValueMap.h
new file mode 100644
index 0000000000..a63671b5e7
--- /dev/null
+++ b/include/llvm/ADT/ValueMap.h
@@ -0,0 +1,365 @@
+//===- llvm/ADT/ValueMap.h - Safe map from Values to data -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the ValueMap class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_VALUEMAP_H
+#define LLVM_ADT_VALUEMAP_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/Support/ValueHandle.h"
+#include "llvm/Support/type_traits.h"
+#include "llvm/System/Mutex.h"
+
+#include <iterator>
+
+namespace llvm {
+
+template<typename KeyT, typename ValueT, typename Config, typename ValueInfoT>
+class ValueMapCallbackVH;
+
+template<typename DenseMapT, typename KeyT>
+class ValueMapIterator;
+template<typename DenseMapT, typename KeyT>
+class ValueMapConstIterator;
+
+template<typename KeyT>
+struct ValueMapConfig {
+  /// If FollowRAUW is true, the ValueMap will update mappings on RAUW. If it's
+  /// false, the ValueMap will leave the original mapping in place.
+  enum { FollowRAUW = true };
+
+  // All methods will be called with a first argument of type ExtraData.  The
+  // default implementations in this class take a templated first argument so
+  // that users' subclasses can use any type they want without having to
+  // override all the defaults.
+  struct ExtraData {};
+
+  template<typename ExtraDataT>
+  static void onRAUW(const ExtraDataT &Data, KeyT Old, KeyT New) {}
+  template<typename ExtraDataT>
+  static void onDeleted(const ExtraDataT &Data, KeyT Old) {}
+
+  /// Returns a mutex that should be acquired around any changes to the map.
+  /// This is only acquired from the CallbackVH (and held around calls to onRAUW
+  /// and onDeleted) and not inside other ValueMap methods.  NULL means that no
+  /// mutex is necessary.
+  template<typename ExtraDataT>
+  static sys::Mutex *getMutex(const ExtraDataT &Data) { return NULL; }
+};
+
+/// ValueMap maps Value* or any subclass to an arbitrary other
+/// type. It provides the DenseMap interface.  When the key values are
+/// deleted or RAUWed, ValueMap relies on the Config to decide what to
+/// do.  Config parameters should inherit from ValueMapConfig<KeyT> to
+/// get default implementations of all the methods ValueMap uses.
+///
+/// By default, when a key is RAUWed from V1 to V2, the old mapping
+/// V1->target is removed, and a new mapping V2->target is added.  If
+/// V2 already existed, its old target is overwritten.  When a key is
+/// deleted, its mapping is removed.  You can override Config to get
+/// called back on each event.
+template<typename KeyT, typename ValueT, typename Config = ValueMapConfig<KeyT>,
+         typename ValueInfoT = DenseMapInfo<ValueT> >
+class ValueMap {
+  friend class ValueMapCallbackVH<KeyT, ValueT, Config, ValueInfoT>;
+  typedef ValueMapCallbackVH<KeyT, ValueT, Config, ValueInfoT> ValueMapCVH;
+  typedef DenseMap<ValueMapCVH, ValueT, DenseMapInfo<ValueMapCVH>,
+                   ValueInfoT> MapT;
+  typedef typename Config::ExtraData ExtraData;
+  MapT Map;
+  ExtraData Data;
+public:
+  typedef KeyT key_type;
+  typedef ValueT mapped_type;
+  typedef std::pair<KeyT, ValueT> value_type;
+
+  ValueMap(const ValueMap& Other) : Map(Other.Map), Data(Other.Data) {}
+
+  explicit ValueMap(unsigned NumInitBuckets = 64)
+    : Map(NumInitBuckets), Data() {}
+  explicit ValueMap(const ExtraData &Data, unsigned NumInitBuckets = 64)
+    : Map(NumInitBuckets), Data(Data) {}
+
+  ~ValueMap() {}
+
+  typedef ValueMapIterator<MapT, KeyT> iterator;
+  typedef ValueMapConstIterator<MapT, KeyT> const_iterator;
+  inline iterator begin() { return iterator(Map.begin()); }
+  inline iterator end() { return iterator(Map.end()); }
+  inline const_iterator begin() const { return const_iterator(Map.begin()); }
+  inline const_iterator end() const { return const_iterator(Map.end()); }
+
+  bool empty() const { return Map.empty(); }
+  unsigned size() const { return Map.size(); }
+
+  /// Grow the map so that it has at least Size buckets. Does not shrink
+  void resize(size_t Size) { Map.resize(Size); }
+
+  void clear() { Map.clear(); }
+
+  /// count - Return true if the specified key is in the map.
+  bool count(const KeyT &Val) const {
+    return Map.count(Wrap(Val));
+  }
+
+  iterator find(const KeyT &Val) {
+    return iterator(Map.find(Wrap(Val)));
+  }
+  const_iterator find(const KeyT &Val) const {
+    return const_iterator(Map.find(Wrap(Val)));
+  }
+
+  /// lookup - Return the entry for the specified key, or a default
+  /// constructed value if no such entry exists.
+  ValueT lookup(const KeyT &Val) const {
+    return Map.lookup(Wrap(Val));
+  }
+
+  // Inserts key,value pair into the map if the key isn't already in the map.
+  // If the key is already in the map, it returns false and doesn't update the
+  // value.
+  std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
+    std::pair<typename MapT::iterator, bool> map_result=
+      Map.insert(std::make_pair(Wrap(KV.first), KV.second));
+    return std::make_pair(iterator(map_result.first), map_result.second);
+  }
+
+  /// insert - Range insertion of pairs.
+  template<typename InputIt>
+  void insert(InputIt I, InputIt E) {
+    for (; I != E; ++I)
+      insert(*I);
+  }
+
+
+  bool erase(const KeyT &Val) {
+    return Map.erase(Wrap(Val));
+  }
+  bool erase(iterator I) {
+    return Map.erase(I.base());
+  }
+
+  value_type& FindAndConstruct(const KeyT &Key) {
+    return Map.FindAndConstruct(Wrap(Key));
+  }
+
+  ValueT &operator[](const KeyT &Key) {
+    return Map[Wrap(Key)];
+  }
+
+  ValueMap& operator=(const ValueMap& Other) {
+    Map = Other.Map;
+    Data = Other.Data;
+    return *this;
+  }
+
+  /// isPointerIntoBucketsArray - Return true if the specified pointer points
+  /// somewhere into the ValueMap's array of buckets (i.e. either to a key or
+  /// value in the ValueMap).
+  bool isPointerIntoBucketsArray(const void *Ptr) const {
+    return Map.isPointerIntoBucketsArray(Ptr);
+  }
+
+  /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
+  /// array.  In conjunction with the previous method, this can be used to
+  /// determine whether an insertion caused the ValueMap to reallocate.
+  const void *getPointerIntoBucketsArray() const {
+    return Map.getPointerIntoBucketsArray();
+  }
+
+private:
+  ValueMapCVH Wrap(KeyT key) const {
+    // The only way the resulting CallbackVH could try to modify *this (making
+    // the const_cast incorrect) is if it gets inserted into the map.  But then
+    // this function must have been called from a non-const method, making the
+    // const_cast ok.
+    return ValueMapCVH(key, const_cast<ValueMap*>(this));
+  }
+};
+
+template<typename KeyT, typename ValueT, typename Config, typename ValueInfoT>
+class ValueMapCallbackVH : public CallbackVH {
+  friend class ValueMap<KeyT, ValueT, Config, ValueInfoT>;
+  friend class DenseMapInfo<ValueMapCallbackVH>;
+  typedef ValueMap<KeyT, ValueT, Config, ValueInfoT> ValueMap;
+  typedef typename llvm::remove_pointer<KeyT>::type KeySansPointerT;
+
+  ValueMap *Map;
+
+  ValueMapCallbackVH(KeyT Key, ValueMap *Map)
+      : CallbackVH(const_cast<Value*>(static_cast<const Value*>(Key))),
+        Map(Map) {}
+
+public:
+  KeyT Unwrap() const { return cast_or_null<KeySansPointerT>(getValPtr()); }
+
+  virtual void deleted() {
+    // Make a copy that won't get changed even when *this is destroyed.
+    ValueMapCallbackVH Copy(*this);
+    sys::Mutex *M = Config::getMutex(Copy.Map->Data);
+    if (M)
+      M->acquire();
+    Config::onDeleted(Copy.Map->Data, Copy.Unwrap());  // May destroy *this.
+    Copy.Map->Map.erase(Copy);  // Definitely destroys *this.
+    if (M)
+      M->release();
+  }
+  virtual void allUsesReplacedWith(Value *new_key) {
+    assert(isa<KeySansPointerT>(new_key) &&
+           "Invalid RAUW on key of ValueMap<>");
+    // Make a copy that won't get changed even when *this is destroyed.
+    ValueMapCallbackVH Copy(*this);
+    sys::Mutex *M = Config::getMutex(Copy.Map->Data);
+    if (M)
+      M->acquire();
+
+    KeyT typed_new_key = cast<KeySansPointerT>(new_key);
+    // Can destroy *this:
+    Config::onRAUW(Copy.Map->Data, Copy.Unwrap(), typed_new_key);
+    if (Config::FollowRAUW) {
+      typename ValueMap::MapT::iterator I = Copy.Map->Map.find(Copy);
+      // I could == Copy.Map->Map.end() if the onRAUW callback already
+      // removed the old mapping.
+      if (I != Copy.Map->Map.end()) {
+        ValueT Target(I->second);
+        Copy.Map->Map.erase(I);  // Definitely destroys *this.
+        Copy.Map->insert(std::make_pair(typed_new_key, Target));
+      }
+    }
+    if (M)
+      M->release();
+  }
+};
+
+template<typename KeyT, typename ValueT, typename Config, typename ValueInfoT>
+struct DenseMapInfo<ValueMapCallbackVH<KeyT, ValueT, Config, ValueInfoT> > {
+  typedef ValueMapCallbackVH<KeyT, ValueT, Config, ValueInfoT> VH;
+  typedef DenseMapInfo<KeyT> PointerInfo;
+
+  static inline VH getEmptyKey() {
+    return VH(PointerInfo::getEmptyKey(), NULL);
+  }
+  static inline VH getTombstoneKey() {
+    return VH(PointerInfo::getTombstoneKey(), NULL);
+  }
+  static unsigned getHashValue(const VH &Val) {
+    return PointerInfo::getHashValue(Val.Unwrap());
+  }
+  static bool isEqual(const VH &LHS, const VH &RHS) {
+    return LHS == RHS;
+  }
+  static bool isPod() { return false; }
+};
+
+
+template<typename DenseMapT, typename KeyT>
+class ValueMapIterator :
+    public std::iterator<std::forward_iterator_tag,
+                         std::pair<KeyT, typename DenseMapT::mapped_type>,
+                         ptrdiff_t> {
+  typedef typename DenseMapT::iterator BaseT;
+  typedef typename DenseMapT::mapped_type ValueT;
+  BaseT I;
+public:
+  ValueMapIterator() : I() {}
+
+  ValueMapIterator(BaseT I) : I(I) {}
+
+  BaseT base() const { return I; }
+
+  struct ValueTypeProxy {
+    const KeyT first;
+    ValueT& second;
+    ValueTypeProxy *operator->()  { return this; }
+    operator std::pair<KeyT, ValueT>() const {
+      return std::make_pair(first, second);
+    }
+  };
+
+  ValueTypeProxy operator*() const {
+    ValueTypeProxy Result = {I->first.Unwrap(), I->second};
+    return Result;
+  }
+
+  ValueTypeProxy operator->() const {
+    return operator*();
+  }
+
+  bool operator==(const ValueMapIterator &RHS) const {
+    return I == RHS.I;
+  }
+  bool operator!=(const ValueMapIterator &RHS) const {
+    return I != RHS.I;
+  }
+
+  inline ValueMapIterator& operator++() {          // Preincrement
+    ++I;
+    return *this;
+  }
+  ValueMapIterator operator++(int) {        // Postincrement
+    ValueMapIterator tmp = *this; ++*this; return tmp;
+  }
+};
+
+template<typename DenseMapT, typename KeyT>
+class ValueMapConstIterator :
+    public std::iterator<std::forward_iterator_tag,
+                         std::pair<KeyT, typename DenseMapT::mapped_type>,
+                         ptrdiff_t> {
+  typedef typename DenseMapT::const_iterator BaseT;
+  typedef typename DenseMapT::mapped_type ValueT;
+  BaseT I;
+public:
+  ValueMapConstIterator() : I() {}
+  ValueMapConstIterator(BaseT I) : I(I) {}
+  ValueMapConstIterator(ValueMapIterator<DenseMapT, KeyT> Other)
+    : I(Other.base()) {}
+
+  BaseT base() const { return I; }
+
+  struct ValueTypeProxy {
+    const KeyT first;
+    const ValueT& second;
+    ValueTypeProxy *operator->()  { return this; }
+    operator std::pair<KeyT, ValueT>() const {
+      return std::make_pair(first, second);
+    }
+  };
+
+  ValueTypeProxy operator*() const {
+    ValueTypeProxy Result = {I->first.Unwrap(), I->second};
+    return Result;
+  }
+
+  ValueTypeProxy operator->() const {
+    return operator*();
+  }
+
+  bool operator==(const ValueMapConstIterator &RHS) const {
+    return I == RHS.I;
+  }
+  bool operator!=(const ValueMapConstIterator &RHS) const {
+    return I != RHS.I;
+  }
+
+  inline ValueMapConstIterator& operator++() {          // Preincrement
+    ++I;
+    return *this;
+  }
+  ValueMapConstIterator operator++(int) {        // Postincrement
+    ValueMapConstIterator tmp = *this; ++*this; return tmp;
+  }
+};
+
+} // end namespace llvm
+
+#endif
diff --git a/include/llvm/Support/type_traits.h b/include/llvm/Support/type_traits.h
index 5f799b850d..cfaae4b841 100644
--- a/include/llvm/Support/type_traits.h
+++ b/include/llvm/Support/type_traits.h
@@ -87,6 +87,15 @@ struct is_base_of {
       sizeof(char) == sizeof(dont_use::base_of_helper<Base>((Derived*)0));
 };
 
+// remove_pointer - Metafunction to turn Foo* into Foo.  Defined in
+// C++0x [meta.trans.ptr].
+template <typename T> struct remove_pointer { typedef T type; };
+template <typename T> struct remove_pointer<T*> { typedef T type; };
+template <typename T> struct remove_pointer<T*const> { typedef T type; };
+template <typename T> struct remove_pointer<T*volatile> { typedef T type; };
+template <typename T> struct remove_pointer<T*const volatile> {
+    typedef T type; };
+
 }
 
 #endif
diff --git a/unittests/ADT/ValueMapTest.cpp b/unittests/ADT/ValueMapTest.cpp
new file mode 100644
index 0000000000..9de340c3f3
--- /dev/null
+++ b/unittests/ADT/ValueMapTest.cpp
@@ -0,0 +1,291 @@
+//===- llvm/unittest/ADT/ValueMapTest.cpp - ValueMap unit tests -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/ValueMap.h"
+
+#include "llvm/Instructions.h"
+#include "llvm/ADT/OwningPtr.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+// Test fixture
+template<typename T>
+class ValueMapTest : public testing::Test {
+protected:
+  Constant *ConstantV;
+  OwningPtr<BitCastInst> BitcastV;
+  OwningPtr<BinaryOperator> AddV;
+
+  ValueMapTest() :
+    ConstantV(ConstantInt::get(Type::getInt32Ty(getGlobalContext()), 0)),
+    BitcastV(new BitCastInst(ConstantV, Type::getInt32Ty(getGlobalContext()))),
+    AddV(BinaryOperator::CreateAdd(ConstantV, ConstantV)) {
+  }
+};
+
+// Run everything on Value*, a subtype to make sure that casting works as
+// expected, and a const subtype to make sure we cast const correctly.
+typedef ::testing::Types<Value, Instruction, const Instruction> KeyTypes;
+TYPED_TEST_CASE(ValueMapTest, KeyTypes);
+
+TYPED_TEST(ValueMapTest, Null) {
+  ValueMap<TypeParam*, int> VM1;
+  VM1[NULL] = 7;
+  EXPECT_EQ(7, VM1.lookup(NULL));
+}
+
+TYPED_TEST(ValueMapTest, FollowsValue) {
+  ValueMap<TypeParam*, int> VM;
+  VM[this->BitcastV.get()] = 7;
+  EXPECT_EQ(7, VM.lookup(this->BitcastV.get()));
+  EXPECT_EQ(0, VM.count(this->AddV.get()));
+  this->BitcastV->replaceAllUsesWith(this->AddV.get());
+  EXPECT_EQ(7, VM.lookup(this->AddV.get()));
+  EXPECT_EQ(0, VM.count(this->BitcastV.get()));
+  this->AddV.reset();
+  EXPECT_EQ(0, VM.count(this->AddV.get()));
+  EXPECT_EQ(0, VM.count(this->BitcastV.get()));
+  EXPECT_EQ(0U, VM.size());
+}
+
+TYPED_TEST(ValueMapTest, OperationsWork) {
+  ValueMap<TypeParam*, int> VM;
+  ValueMap<TypeParam*, int> VM2(16);
+  typename ValueMapConfig<TypeParam*>::ExtraData Data;
+  ValueMap<TypeParam*, int> VM3(Data, 16);
+  EXPECT_TRUE(VM.empty());
+
+  VM[this->BitcastV.get()] = 7;
+
+  // Find:
+  typename ValueMap<TypeParam*, int>::iterator I =
+    VM.find(this->BitcastV.get());
+  ASSERT_TRUE(I != VM.end());
+  EXPECT_EQ(this->BitcastV.get(), I->first);
+  EXPECT_EQ(7, I->second);
+  EXPECT_TRUE(VM.find(this->AddV.get()) == VM.end());
+
+  // Const find:
+  const ValueMap<TypeParam*, int> &CVM = VM;
+  typename ValueMap<TypeParam*, int>::const_iterator CI =
+    CVM.find(this->BitcastV.get());
+  ASSERT_TRUE(CI != CVM.end());
+  EXPECT_EQ(this->BitcastV.get(), CI->first);
+  EXPECT_EQ(7, CI->second);
+  EXPECT_TRUE(CVM.find(this->AddV.get()) == CVM.end());
+
+  // Insert:
+  std::pair<typename ValueMap<TypeParam*, int>::iterator, bool> InsertResult1 =
+    VM.insert(std::make_pair(this->AddV.get(), 3));
+  EXPECT_EQ(this->AddV.get(), InsertResult1.first->first);
+  EXPECT_EQ(3, InsertResult1.first->second);
+  EXPECT_TRUE(InsertResult1.second);
+  EXPECT_EQ(true, VM.count(this->AddV.get()));
+  std::pair<typename ValueMap<TypeParam*, int>::iterator, bool> InsertResult2 =
+    VM.insert(std::make_pair(this->AddV.get(), 5));
+  EXPECT_EQ(this->AddV.get(), InsertResult2.first->first);
+  EXPECT_EQ(3, InsertResult2.first->second);
+  EXPECT_FALSE(InsertResult2.second);
+
+  // Erase:
+  VM.erase(InsertResult2.first);
+  EXPECT_EQ(false, VM.count(this->AddV.get()));
+  EXPECT_EQ(true, VM.count(this->BitcastV.get()));
+  VM.erase(this->BitcastV.get());
+  EXPECT_EQ(false, VM.count(this->BitcastV.get()));
+  EXPECT_EQ(0U, VM.size());
+
+  // Range insert:
+  SmallVector<std::pair<Instruction*, int>, 2> Elems;
+  Elems.push_back(std::make_pair(this->AddV.get(), 1));
+  Elems.push_back(std::make_pair(this->BitcastV.get(), 2));
+  VM.insert(Elems.begin(), Elems.end());
+  EXPECT_EQ(1, VM.lookup(this->AddV.get()));
+  EXPECT_EQ(2, VM.lookup(this->BitcastV.get()));
+}
+
+template<typename ExpectedType, typename VarType>
+void CompileAssertHasType(VarType) {
+  typedef char assert[is_same<ExpectedType, VarType>::value ? 1 : -1];
+}
+
+TYPED_TEST(ValueMapTest, Iteration) {
+  ValueMap<TypeParam*, int> VM;
+  VM[this->BitcastV.get()] = 2;
+  VM[this->AddV.get()] = 3;
+  size_t size = 0;
+  for (typename ValueMap<TypeParam*, int>::iterator I = VM.begin(), E = VM.end();
+       I != E; ++I) {
+    ++size;
+    std::pair<TypeParam*, int> value = *I;
+    CompileAssertHasType<TypeParam*>(I->first);
+    if (I->second == 2) {
+      EXPECT_EQ(this->BitcastV.get(), I->first);
+      I->second = 5;
+    } else if (I->second == 3) {
+      EXPECT_EQ(this->AddV.get(), I->first);
+      I->second = 6;
+    } else {
+      ADD_FAILURE() << "Iterated through an extra value.";
+    }
+  }
+  EXPECT_EQ(2U, size);
+  EXPECT_EQ(5, VM[this->BitcastV.get()]);
+  EXPECT_EQ(6, VM[this->AddV.get()]);
+
+  size = 0;
+  // Cast to const ValueMap to avoid a bug in DenseMap's iterators.
+  const ValueMap<TypeParam*, int>& CVM = VM;
+  for (typename ValueMap<TypeParam*, int>::const_iterator I = CVM.begin(),
+         E = CVM.end(); I != E; ++I) {
+    ++size;
+    std::pair<TypeParam*, int> value = *I;
+    CompileAssertHasType<TypeParam*>(I->first);
+    if (I->second == 5) {
+      EXPECT_EQ(this->BitcastV.get(), I->first);
+    } else if (I->second == 6) {
+      EXPECT_EQ(this->AddV.get(), I->first);
+    } else {
+      ADD_FAILURE() << "Iterated through an extra value.";
+    }
+  }
+  EXPECT_EQ(2U, size);
+}
+
+TYPED_TEST(ValueMapTest, DefaultCollisionBehavior) {
+  // By default, we overwrite the old value with the replaced value.
+  ValueMap<TypeParam*, int> VM;
+  VM[this->BitcastV.get()] = 7;
+  VM[this->AddV.get()] = 9;
+  this->BitcastV->replaceAllUsesWith(this->AddV.get());
+  EXPECT_EQ(0, VM.count(this->BitcastV.get()));
+  EXPECT_EQ(9, VM.lookup(this->AddV.get()));
+}
+
+TYPED_TEST(ValueMapTest, ConfiguredCollisionBehavior) {
+  // TODO: Implement this when someone needs it.
+}
+
+template<typename KeyT>
+struct LockMutex : ValueMapConfig<KeyT> {
+  struct ExtraData {
+    sys::Mutex *M;
+    bool *CalledRAUW;
+    bool *CalledDeleted;
+  };
+  static void onRAUW(const ExtraData &Data, KeyT Old, KeyT New) {
+    *Data.CalledRAUW = true;
+    EXPECT_FALSE(Data.M->tryacquire()) << "Mutex should already be locked.";
+  }
+  static void onDeleted(const ExtraData &Data, KeyT Old) {
+    *Data.CalledDeleted = true;
+    EXPECT_FALSE(Data.M->tryacquire()) << "Mutex should already be locked.";
+  }
+  static sys::Mutex *getMutex(const ExtraData &Data) { return Data.M; }
+};
+TYPED_TEST(ValueMapTest, LocksMutex) {
+  sys::Mutex M(false);  // Not recursive.
+  bool CalledRAUW = false, CalledDeleted = false;
+  typename LockMutex<TypeParam*>::ExtraData Data =
+    {&M, &CalledRAUW, &CalledDeleted};
+  ValueMap<TypeParam*, int, LockMutex<TypeParam*> > VM(Data);
+  VM[this->BitcastV.get()] = 7;
+  this->BitcastV->replaceAllUsesWith(this->AddV.get());
+  this->AddV.reset();
+  EXPECT_TRUE(CalledRAUW);
+  EXPECT_TRUE(CalledDeleted);
+}
+
+template<typename KeyT>
+struct NoFollow : ValueMapConfig<KeyT> {
+  enum { FollowRAUW = false };
+};
+
+TYPED_TEST(ValueMapTest, NoFollowRAUW) {
+  ValueMap<TypeParam*, int, NoFollow<TypeParam*> > VM;
+  VM[this->BitcastV.get()] = 7;
+  EXPECT_EQ(7, VM.lookup(this->BitcastV.get()));
+  EXPECT_EQ(0, VM.count(this->AddV.get()));
+  this->BitcastV->replaceAllUsesWith(this->AddV.get());
+  EXPECT_EQ(7, VM.lookup(this->BitcastV.get()));
+  EXPECT_EQ(0, VM.lookup(this->AddV.get()));
+  this->AddV.reset();
+  EXPECT_EQ(7, VM.lookup(this->BitcastV.get()));
+  EXPECT_EQ(0, VM.lookup(this->AddV.get()));
+  this->BitcastV.reset();
+  EXPECT_EQ(0, VM.lookup(this->BitcastV.get()));
+  EXPECT_EQ(0, VM.lookup(this->AddV.get()));
+  EXPECT_EQ(0U, VM.size());
+}
+
+template<typename KeyT>
+struct CountOps : ValueMapConfig<KeyT> {
+  struct ExtraData {
+    int *Deletions;
+    int *RAUWs;
+  };
+
+  static void onRAUW(const ExtraData &Data, KeyT Old, KeyT New) {
+    ++*Data.RAUWs;
+  }
+  static void onDeleted(const ExtraData &Data, KeyT Old) {
+    ++*Data.Deletions;
+  }
+};
+
+TYPED_TEST(ValueMapTest, CallsConfig) {
+  int Deletions = 0, RAUWs = 0;
+  typename CountOps<TypeParam*>::ExtraData Data = {&Deletions, &RAUWs};
+  ValueMap<TypeParam*, int, CountOps<TypeParam*> > VM(Data);
+  VM[this->BitcastV.get()] = 7;
+  this->BitcastV->replaceAllUsesWith(this->AddV.get());
+  EXPECT_EQ(0, Deletions);
+  EXPECT_EQ(1, RAUWs);
+  this->AddV.reset();
+  EXPECT_EQ(1, Deletions);
+  EXPECT_EQ(1, RAUWs);
+  this->BitcastV.reset();
+  EXPECT_EQ(1, Deletions);
+  EXPECT_EQ(1, RAUWs);
+}
+
+template<typename KeyT>
+struct ModifyingConfig : ValueMapConfig<KeyT> {
+  // We'll put a pointer here back to the ValueMap this key is in, so
+  // that we can modify it (and clobber *this) before the ValueMap
+  // tries to do the same modification.  In previous versions of
+  // ValueMap, that exploded.
+  typedef ValueMap<KeyT, int, ModifyingConfig<KeyT> > **ExtraData;
+
+  static void onRAUW(ExtraData Map, KeyT Old, KeyT New) {
+    (*Map)->erase(Old);
+  }
+  static void onDeleted(ExtraData Map, KeyT Old) {
+    (*Map)->erase(Old);
+  }
+};
+TYPED_TEST(ValueMapTest, SurvivesModificationByConfig) {
+  ValueMap<TypeParam*, int, ModifyingConfig<TypeParam*> > *MapAddress;
+  ValueMap<TypeParam*, int, ModifyingConfig<TypeParam*> > VM(&MapAddress);
+  MapAddress = &VM;
+  // Now the ModifyingConfig can modify the Map inside a callback.
+  VM[this->BitcastV.get()] = 7;
+  this->BitcastV->replaceAllUsesWith(this->AddV.get());
+  EXPECT_FALSE(VM.count(this->BitcastV.get()));
+  EXPECT_FALSE(VM.count(this->AddV.get()));
+  VM[this->AddV.get()] = 7;
+  this->AddV.reset();
+  EXPECT_FALSE(VM.count(this->AddV.get()));
+}
+
+}