Merge "Update prebuilt Clang to r353983." into p9.0HEADp9.0-backupp9.0

1 files changed, 269 insertions, 0 deletions

diff --git a/clang-r353983/include/llvm/ADT/IntrusiveRefCntPtr.h b/clang-r353983/include/llvm/ADT/IntrusiveRefCntPtr.h
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+++ b/clang-r353983/include/llvm/ADT/IntrusiveRefCntPtr.h
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+//==- llvm/ADT/IntrusiveRefCntPtr.h - Smart Refcounting Pointer --*- C++ -*-==//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the RefCountedBase, ThreadSafeRefCountedBase, and
+// IntrusiveRefCntPtr classes.
+//
+// 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.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_INTRUSIVEREFCNTPTR_H
+#define LLVM_ADT_INTRUSIVEREFCNTPTR_H
+
+#include <atomic>
+#include <cassert>
+#include <cstddef>
+
+namespace llvm {
+
+/// 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 &) {}
+
+  void Retain() const { ++RefCount; }
+
+  void Release() const {
+    assert(RefCount > 0 && "Reference count is already zero.");
+    if (--RefCount == 0)
+      delete static_cast<const Derived *>(this);
+  }
+};
+
+/// 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.fetch_add(1, std::memory_order_relaxed); }
+
+  void Release() const {
+    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);
+  }
+};
+
+/// Class you can specialize to provide custom retain/release functionality for
+/// a type.
+///
+/// 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(); }
+};
+
+/// 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;
+
+public:
+  using element_type = T;
+
+  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 X>
+  IntrusiveRefCntPtr(IntrusiveRefCntPtr<X> &&S) : Obj(S.get()) {
+    S.Obj = nullptr;
+  }
+
+  template <class X>
+  IntrusiveRefCntPtr(const IntrusiveRefCntPtr<X> &S) : Obj(S.get()) {
+    retain();
+  }
+
+  ~IntrusiveRefCntPtr() { release(); }
+
+  IntrusiveRefCntPtr &operator=(IntrusiveRefCntPtr S) {
+    swap(S);
+    return *this;
+  }
+
+  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;
+  }
+
+  void resetWithoutRelease() { Obj = nullptr; }
+
+private:
+  void retain() {
+    if (Obj)
+      IntrusiveRefCntPtrInfo<T>::retain(Obj);
+  }
+
+  void release() {
+    if (Obj)
+      IntrusiveRefCntPtrInfo<T>::release(Obj);
+  }
+
+  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>> {
+  using SimpleType = T *;
+
+  static SimpleType getSimplifiedValue(IntrusiveRefCntPtr<T> &Val) {
+    return Val.get();
+  }
+};
+
+template <class T> struct simplify_type<const IntrusiveRefCntPtr<T>> {
+  using SimpleType = /*const*/ T *;
+
+  static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T> &Val) {
+    return Val.get();
+  }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_ADT_INTRUSIVEREFCNTPTR_H