Merge webkit.org at R49305 : Automatic merge by git.

Change-Id: I8968561bc1bfd72b8923b7118d3728579c6dbcc7

1 files changed, 74 insertions, 7 deletions

diff --git a/JavaScriptCore/wtf/PassRefPtr.h b/JavaScriptCore/wtf/PassRefPtr.h
index d80ed62..36ba78e 100644
--- a/JavaScriptCore/wtf/PassRefPtr.h
+++ b/JavaScriptCore/wtf/PassRefPtr.h
@@ -28,6 +28,19 @@ namespace WTF {
     template<typename T> class RefPtr;
     template<typename T> class PassRefPtr;
     template <typename T> PassRefPtr<T> adoptRef(T*);
+    
+    // Remove inline for winscw compiler to prevent the compiler agressively resolving 
+    // T::deref(), which will fail compiling when PassRefPtr<T> is used as class member 
+    // or function arguments before T is defined.
+    template<typename T> 
+#if !COMPILER(WINSCW)
+    inline 
+#endif
+    void derefIfNotNull(T* ptr)
+    {
+        if (UNLIKELY(ptr != 0))
+            ptr->deref();
+    }
 
     template<typename T> class PassRefPtr {
     public:
@@ -40,8 +53,8 @@ namespace WTF {
         PassRefPtr(const PassRefPtr& o) : m_ptr(o.releaseRef()) {}
         template <typename U> PassRefPtr(const PassRefPtr<U>& o) : m_ptr(o.releaseRef()) { }
 
-        ALWAYS_INLINE ~PassRefPtr() { if (UNLIKELY(m_ptr != 0)) m_ptr->deref(); }
-        
+        ALWAYS_INLINE ~PassRefPtr() { derefIfNotNull<T>(m_ptr); }
+
         template <class U> 
         PassRefPtr(const RefPtr<U>& o) : m_ptr(o.get()) { if (T* ptr = m_ptr) ptr->ref(); }
         
@@ -56,12 +69,9 @@ namespace WTF {
         bool operator!() const { return !m_ptr; }
 
         // This conversion operator allows implicit conversion to bool but not to other integer types.
-#if COMPILER(WINSCW)
-        operator bool() const { return m_ptr; }
-#else
-        typedef T* PassRefPtr::*UnspecifiedBoolType;
+        typedef T* (PassRefPtr::*UnspecifiedBoolType);
         operator UnspecifiedBoolType() const { return m_ptr ? &PassRefPtr::m_ptr : 0; }
-#endif
+
         PassRefPtr& operator=(T*);
         PassRefPtr& operator=(const PassRefPtr&);
         template <typename U> PassRefPtr& operator=(const PassRefPtr<U>&);
@@ -74,6 +84,62 @@ namespace WTF {
         mutable T* m_ptr;
     };
     
+    // NonNullPassRefPtr: Optimized for passing non-null pointers. A NonNullPassRefPtr
+    // begins life non-null, and can only become null through a call to releaseRef()
+    // or clear().
+
+    // FIXME: NonNullPassRefPtr could just inherit from PassRefPtr. However,
+    // if we use inheritance, GCC's optimizer fails to realize that destruction
+    // of a released NonNullPassRefPtr is a no-op. So, for now, just copy the
+    // most important code from PassRefPtr.
+    template <typename T> class NonNullPassRefPtr {
+    public:
+        NonNullPassRefPtr(T* ptr)
+            : m_ptr(ptr)
+        {
+            ASSERT(m_ptr);
+            m_ptr->ref();
+        }
+
+        template <class U> NonNullPassRefPtr(const RefPtr<U>& o)
+            : m_ptr(o.get())
+        {
+            ASSERT(m_ptr);
+            m_ptr->ref();
+        }
+
+        NonNullPassRefPtr(const NonNullPassRefPtr& o)
+            : m_ptr(o.releaseRef())
+        {
+            ASSERT(m_ptr);
+        }
+
+        template <class U> NonNullPassRefPtr(const NonNullPassRefPtr<U>& o)
+            : m_ptr(o.releaseRef())
+        {
+            ASSERT(m_ptr);
+        }
+
+        template <class U> NonNullPassRefPtr(const PassRefPtr<U>& o)
+            : m_ptr(o.releaseRef())
+        {
+            ASSERT(m_ptr);
+        }
+
+        ALWAYS_INLINE ~NonNullPassRefPtr() { derefIfNotNull(m_ptr); }
+
+        T* get() const { return m_ptr; }
+
+        void clear() { derefIfNotNull(m_ptr); m_ptr = 0; }
+        T* releaseRef() const { T* tmp = m_ptr; m_ptr = 0; return tmp; }
+
+        T& operator*() const { return *m_ptr; }
+        T* operator->() const { return m_ptr; }
+
+    private:
+        mutable T* m_ptr;
+    };
+
     template <typename T> template <typename U> inline PassRefPtr<T>& PassRefPtr<T>::operator=(const RefPtr<U>& o) 
     {
         T* optr = o.get();
@@ -188,6 +254,7 @@ namespace WTF {
 } // namespace WTF
 
 using WTF::PassRefPtr;
+using WTF::NonNullPassRefPtr;
 using WTF::adoptRef;
 using WTF::static_pointer_cast;
 using WTF::const_pointer_cast;