1 files changed, 202 insertions, 224 deletions

diff --git a/contrib/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h b/contrib/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h
index 8057ec1..a77cf04 100644
--- a/contrib/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h
+++ b/contrib/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h
@@ -7,14 +7,49 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file defines IntrusiveRefCntPtr, a template class that
-// implements a "smart" pointer for objects that maintain their own
-// internal reference count, and RefCountedBase/RefCountedBaseVPTR, two
-// generic base classes for objects that wish to have their lifetimes
-// managed using reference counting.
+// This file defines the RefCountedBase, ThreadSafeRefCountedBase, and
+// IntrusiveRefCntPtr classes.
 //
-// IntrusiveRefCntPtr is similar to Boost's intrusive_ptr with added
-// LLVM-style casting.
+// IntrusiveRefCntPtr is a smart pointer to an object which maintains a
+// reference count.  (ThreadSafe)RefCountedBase is a mixin class that adds a
+// refcount member variable and methods for updating the refcount.  An object
+// that inherits from (ThreadSafe)RefCountedBase deletes itself when its
+// refcount hits zero.
+//
+// For example:
+//
+//   class MyClass : public RefCountedBase<MyClass> {};
+//
+//   void foo() {
+//     // Constructing an IntrusiveRefCntPtr increases the pointee's refcount by
+//     // 1 (from 0 in this case).
+//     IntrusiveRefCntPtr<MyClass> Ptr1(new MyClass());
+//
+//     // Copying an IntrusiveRefCntPtr increases the pointee's refcount by 1.
+//     IntrusiveRefCntPtr<MyClass> Ptr2(Ptr1);
+//
+//     // Constructing an IntrusiveRefCntPtr has no effect on the object's
+//     // refcount.  After a move, the moved-from pointer is null.
+//     IntrusiveRefCntPtr<MyClass> Ptr3(std::move(Ptr1));
+//     assert(Ptr1 == nullptr);
+//
+//     // Clearing an IntrusiveRefCntPtr decreases the pointee's refcount by 1.
+//     Ptr2.reset();
+//
+//     // The object deletes itself when we return from the function, because
+//     // Ptr3's destructor decrements its refcount to 0.
+//   }
+//
+// You can use IntrusiveRefCntPtr with isa<T>(), dyn_cast<T>(), etc.:
+//
+//   IntrusiveRefCntPtr<MyClass> Ptr(new MyClass());
+//   OtherClass *Other = dyn_cast<OtherClass>(Ptr);  // Ptr.get() not required
+//
+// IntrusiveRefCntPtr works with any class that
+//
+//  - inherits from (ThreadSafe)RefCountedBase,
+//  - has Retain() and Release() methods, or
+//  - specializes IntrusiveRefCntPtrInfo.
 //
 //===----------------------------------------------------------------------===//
 
@@ -27,261 +62,204 @@
 
 namespace llvm {
 
-  template <class T>
-  class IntrusiveRefCntPtr;
-
-//===----------------------------------------------------------------------===//
-/// RefCountedBase - A generic base class for objects that wish to
-///  have their lifetimes managed using reference counts. Classes
-///  subclass RefCountedBase to obtain such functionality, and are
-///  typically handled with IntrusiveRefCntPtr "smart pointers" (see below)
-///  which automatically handle the management of reference counts.
-///  Objects that subclass RefCountedBase should not be allocated on
-///  the stack, as invoking "delete" (which is called when the
-///  reference count hits 0) on such objects is an error.
-//===----------------------------------------------------------------------===//
-  template <class Derived>
-  class RefCountedBase {
-    mutable unsigned ref_cnt;
-
-  public:
-    RefCountedBase() : ref_cnt(0) {}
-    RefCountedBase(const RefCountedBase &) : ref_cnt(0) {}
-
-    void Retain() const { ++ref_cnt; }
-    void Release() const {
-      assert (ref_cnt > 0 && "Reference count is already zero.");
-      if (--ref_cnt == 0) delete static_cast<const Derived*>(this);
-    }
-  };
-
-//===----------------------------------------------------------------------===//
-/// RefCountedBaseVPTR - A class that has the same function as
-///  RefCountedBase, but with a virtual destructor. Should be used
-///  instead of RefCountedBase for classes that already have virtual
-///  methods to enforce dynamic allocation via 'new'. Classes that
-///  inherit from RefCountedBaseVPTR can't be allocated on stack -
-///  attempting to do this will produce a compile error.
-//===----------------------------------------------------------------------===//
-  class RefCountedBaseVPTR {
-    mutable unsigned ref_cnt;
-    virtual void anchor();
-
-  protected:
-    RefCountedBaseVPTR() : ref_cnt(0) {}
-    RefCountedBaseVPTR(const RefCountedBaseVPTR &) : ref_cnt(0) {}
-
-    virtual ~RefCountedBaseVPTR() {}
-
-    void Retain() const { ++ref_cnt; }
-    void Release() const {
-      assert (ref_cnt > 0 && "Reference count is already zero.");
-      if (--ref_cnt == 0) delete this;
-    }
-
-    template <typename T>
-    friend struct IntrusiveRefCntPtrInfo;
-  };
+/// A CRTP mixin class that adds reference counting to a type.
+///
+/// The lifetime of an object which inherits from RefCountedBase is managed by
+/// calls to Release() and Retain(), which increment and decrement the object's
+/// refcount, respectively.  When a Release() call decrements the refcount to 0,
+/// the object deletes itself.
+template <class Derived> class RefCountedBase {
+  mutable unsigned RefCount = 0;
 
+public:
+  RefCountedBase() = default;
+  RefCountedBase(const RefCountedBase &) : RefCount(0) {}
 
-  template <typename T> struct IntrusiveRefCntPtrInfo {
-    static void retain(T *obj) { obj->Retain(); }
-    static void release(T *obj) { obj->Release(); }
-  };
+  void Retain() const { ++RefCount; }
+  void Release() const {
+    assert(RefCount > 0 && "Reference count is already zero.");
+    if (--RefCount == 0)
+      delete static_cast<const Derived *>(this);
+  }
+};
 
-/// \brief A thread-safe version of \c llvm::RefCountedBase.
-///
-/// A generic base class for objects that wish to have their lifetimes managed
-/// using reference counts. Classes subclass \c ThreadSafeRefCountedBase to
-/// obtain such functionality, and are typically handled with
-/// \c IntrusiveRefCntPtr "smart pointers" which automatically handle the
-/// management of reference counts.
-template <class Derived>
-class ThreadSafeRefCountedBase {
+/// A thread-safe version of \c RefCountedBase.
+template <class Derived> class ThreadSafeRefCountedBase {
   mutable std::atomic<int> RefCount;
 
 protected:
   ThreadSafeRefCountedBase() : RefCount(0) {}
 
 public:
-  void Retain() const { ++RefCount; }
+  void Retain() const { RefCount.fetch_add(1, std::memory_order_relaxed); }
 
   void Release() const {
-    int NewRefCount = --RefCount;
+    int NewRefCount = RefCount.fetch_sub(1, std::memory_order_acq_rel) - 1;
     assert(NewRefCount >= 0 && "Reference count was already zero.");
     if (NewRefCount == 0)
-      delete static_cast<const Derived*>(this);
+      delete static_cast<const Derived *>(this);
   }
 };
 
-//===----------------------------------------------------------------------===//
-/// IntrusiveRefCntPtr - A template class that implements a "smart pointer"
-///  that assumes the wrapped object has a reference count associated
-///  with it that can be managed via calls to
-///  IntrusivePtrAddRef/IntrusivePtrRelease.  The smart pointers
-///  manage reference counts via the RAII idiom: upon creation of
-///  smart pointer the reference count of the wrapped object is
-///  incremented and upon destruction of the smart pointer the
-///  reference count is decremented.  This class also safely handles
-///  wrapping NULL pointers.
+/// Class you can specialize to provide custom retain/release functionality for
+/// a type.
 ///
-/// Reference counting is implemented via calls to
-///  Obj->Retain()/Obj->Release(). Release() is required to destroy
-///  the object when the reference count reaches zero. Inheriting from
-///  RefCountedBase/RefCountedBaseVPTR takes care of this
-///  automatically.
-//===----------------------------------------------------------------------===//
-  template <typename T>
-  class IntrusiveRefCntPtr {
-    T* Obj;
-
-  public:
-    typedef T element_type;
-
-    explicit IntrusiveRefCntPtr() : Obj(nullptr) {}
-
-    IntrusiveRefCntPtr(T* obj) : Obj(obj) {
-      retain();
-    }
-
-    IntrusiveRefCntPtr(const IntrusiveRefCntPtr& S) : Obj(S.Obj) {
-      retain();
-    }
-
-    IntrusiveRefCntPtr(IntrusiveRefCntPtr&& S) : Obj(S.Obj) {
-      S.Obj = nullptr;
-    }
-
-    template <class X>
-    IntrusiveRefCntPtr(IntrusiveRefCntPtr<X>&& S) : Obj(S.get()) {
-      S.Obj = nullptr;
-    }
-
-    template <class X>
-    IntrusiveRefCntPtr(const IntrusiveRefCntPtr<X>& S)
-      : Obj(S.get()) {
-      retain();
-    }
-
-    IntrusiveRefCntPtr& operator=(IntrusiveRefCntPtr S) {
-      swap(S);
-      return *this;
-    }
-
-    ~IntrusiveRefCntPtr() { release(); }
-
-    T& operator*() const { return *Obj; }
-
-    T* operator->() const { return Obj; }
-
-    T* get() const { return Obj; }
-
-    explicit operator bool() const { return Obj; }
-
-    void swap(IntrusiveRefCntPtr& other) {
-      T* tmp = other.Obj;
-      other.Obj = Obj;
-      Obj = tmp;
-    }
-
-    void reset() {
-      release();
-      Obj = nullptr;
-    }
+/// Usually specializing this class is not necessary, as IntrusiveRefCntPtr
+/// works with any type which defines Retain() and Release() functions -- you
+/// can define those functions yourself if RefCountedBase doesn't work for you.
+///
+/// One case when you might want to specialize this type is if you have
+///  - Foo.h defines type Foo and includes Bar.h, and
+///  - Bar.h uses IntrusiveRefCntPtr<Foo> in inline functions.
+///
+/// Because Foo.h includes Bar.h, Bar.h can't include Foo.h in order to pull in
+/// the declaration of Foo.  Without the declaration of Foo, normally Bar.h
+/// wouldn't be able to use IntrusiveRefCntPtr<Foo>, which wants to call
+/// T::Retain and T::Release.
+///
+/// To resolve this, Bar.h could include a third header, FooFwd.h, which
+/// forward-declares Foo and specializes IntrusiveRefCntPtrInfo<Foo>.  Then
+/// Bar.h could use IntrusiveRefCntPtr<Foo>, although it still couldn't call any
+/// functions on Foo itself, because Foo would be an incomplete type.
+template <typename T> struct IntrusiveRefCntPtrInfo {
+  static void retain(T *obj) { obj->Retain(); }
+  static void release(T *obj) { obj->Release(); }
+};
 
-    void resetWithoutRelease() {
-      Obj = nullptr;
-    }
+/// A smart pointer to a reference-counted object that inherits from
+/// RefCountedBase or ThreadSafeRefCountedBase.
+///
+/// This class increments its pointee's reference count when it is created, and
+/// decrements its refcount when it's destroyed (or is changed to point to a
+/// different object).
+template <typename T> class IntrusiveRefCntPtr {
+  T *Obj = nullptr;
 
-  private:
-    void retain() { if (Obj) IntrusiveRefCntPtrInfo<T>::retain(Obj); }
-    void release() { if (Obj) IntrusiveRefCntPtrInfo<T>::release(Obj); }
+public:
+  typedef T element_type;
 
-    template <typename X>
-    friend class IntrusiveRefCntPtr;
-  };
+  explicit IntrusiveRefCntPtr() = default;
+  IntrusiveRefCntPtr(T *obj) : Obj(obj) { retain(); }
+  IntrusiveRefCntPtr(const IntrusiveRefCntPtr &S) : Obj(S.Obj) { retain(); }
+  IntrusiveRefCntPtr(IntrusiveRefCntPtr &&S) : Obj(S.Obj) { S.Obj = nullptr; }
 
-  template<class T, class U>
-  inline bool operator==(const IntrusiveRefCntPtr<T>& A,
-                         const IntrusiveRefCntPtr<U>& B)
-  {
-    return A.get() == B.get();
+  template <class X>
+  IntrusiveRefCntPtr(IntrusiveRefCntPtr<X> &&S) : Obj(S.get()) {
+    S.Obj = nullptr;
   }
 
-  template<class T, class U>
-  inline bool operator!=(const IntrusiveRefCntPtr<T>& A,
-                         const IntrusiveRefCntPtr<U>& B)
-  {
-    return A.get() != B.get();
+  template <class X>
+  IntrusiveRefCntPtr(const IntrusiveRefCntPtr<X> &S) : Obj(S.get()) {
+    retain();
   }
 
-  template<class T, class U>
-  inline bool operator==(const IntrusiveRefCntPtr<T>& A,
-                         U* B)
-  {
-    return A.get() == B;
+  IntrusiveRefCntPtr &operator=(IntrusiveRefCntPtr S) {
+    swap(S);
+    return *this;
   }
 
-  template<class T, class U>
-  inline bool operator!=(const IntrusiveRefCntPtr<T>& A,
-                         U* B)
-  {
-    return A.get() != B;
-  }
+  ~IntrusiveRefCntPtr() { release(); }
 
-  template<class T, class U>
-  inline bool operator==(T* A,
-                         const IntrusiveRefCntPtr<U>& B)
-  {
-    return A == B.get();
-  }
+  T &operator*() const { return *Obj; }
+  T *operator->() const { return Obj; }
+  T *get() const { return Obj; }
+  explicit operator bool() const { return Obj; }
 
-  template<class T, class U>
-  inline bool operator!=(T* A,
-                         const IntrusiveRefCntPtr<U>& B)
-  {
-    return A != B.get();
+  void swap(IntrusiveRefCntPtr &other) {
+    T *tmp = other.Obj;
+    other.Obj = Obj;
+    Obj = tmp;
   }
 
-  template <class T>
-  bool operator==(std::nullptr_t A, const IntrusiveRefCntPtr<T> &B) {
-    return !B;
+  void reset() {
+    release();
+    Obj = nullptr;
   }
 
-  template <class T>
-  bool operator==(const IntrusiveRefCntPtr<T> &A, std::nullptr_t B) {
-    return B == A;
-  }
+  void resetWithoutRelease() { Obj = nullptr; }
 
-  template <class T>
-  bool operator!=(std::nullptr_t A, const IntrusiveRefCntPtr<T> &B) {
-    return !(A == B);
+private:
+  void retain() {
+    if (Obj)
+      IntrusiveRefCntPtrInfo<T>::retain(Obj);
   }
-
-  template <class T>
-  bool operator!=(const IntrusiveRefCntPtr<T> &A, std::nullptr_t B) {
-    return !(A == B);
+  void release() {
+    if (Obj)
+      IntrusiveRefCntPtrInfo<T>::release(Obj);
   }
 
-//===----------------------------------------------------------------------===//
-// LLVM-style downcasting support for IntrusiveRefCntPtr objects
-//===----------------------------------------------------------------------===//
+  template <typename X> friend class IntrusiveRefCntPtr;
+};
+
+template <class T, class U>
+inline bool operator==(const IntrusiveRefCntPtr<T> &A,
+                       const IntrusiveRefCntPtr<U> &B) {
+  return A.get() == B.get();
+}
+
+template <class T, class U>
+inline bool operator!=(const IntrusiveRefCntPtr<T> &A,
+                       const IntrusiveRefCntPtr<U> &B) {
+  return A.get() != B.get();
+}
+
+template <class T, class U>
+inline bool operator==(const IntrusiveRefCntPtr<T> &A, U *B) {
+  return A.get() == B;
+}
+
+template <class T, class U>
+inline bool operator!=(const IntrusiveRefCntPtr<T> &A, U *B) {
+  return A.get() != B;
+}
+
+template <class T, class U>
+inline bool operator==(T *A, const IntrusiveRefCntPtr<U> &B) {
+  return A == B.get();
+}
+
+template <class T, class U>
+inline bool operator!=(T *A, const IntrusiveRefCntPtr<U> &B) {
+  return A != B.get();
+}
+
+template <class T>
+bool operator==(std::nullptr_t A, const IntrusiveRefCntPtr<T> &B) {
+  return !B;
+}
+
+template <class T>
+bool operator==(const IntrusiveRefCntPtr<T> &A, std::nullptr_t B) {
+  return B == A;
+}
+
+template <class T>
+bool operator!=(std::nullptr_t A, const IntrusiveRefCntPtr<T> &B) {
+  return !(A == B);
+}
+
+template <class T>
+bool operator!=(const IntrusiveRefCntPtr<T> &A, std::nullptr_t B) {
+  return !(A == B);
+}
+
+// Make IntrusiveRefCntPtr work with dyn_cast, isa, and the other idioms from
+// Casting.h.
+template <typename From> struct simplify_type;
+
+template <class T> struct simplify_type<IntrusiveRefCntPtr<T>> {
+  typedef T *SimpleType;
+  static SimpleType getSimplifiedValue(IntrusiveRefCntPtr<T> &Val) {
+    return Val.get();
+  }
+};
 
-  template <typename From> struct simplify_type;
-
-  template<class T> struct simplify_type<IntrusiveRefCntPtr<T> > {
-    typedef T* SimpleType;
-    static SimpleType getSimplifiedValue(IntrusiveRefCntPtr<T>& Val) {
-      return Val.get();
-    }
-  };
-
-  template<class T> struct simplify_type<const IntrusiveRefCntPtr<T> > {
-    typedef /*const*/ T* SimpleType;
-    static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) {
-      return Val.get();
-    }
-  };
+template <class T> struct simplify_type<const IntrusiveRefCntPtr<T>> {
+  typedef /*const*/ T *SimpleType;
+  static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T> &Val) {
+    return Val.get();
+  }
+};
 
 } // end namespace llvm