Changeset 68414 in webkit

Timestamp:

Sep 27, 2010 12:18:17 PM (14 years ago)

Author:

andersca@apple.com

Message:

Add WTF_MAKE_NONCOPYABLE macro
​https://bugs.webkit.org/show_bug.cgi?id=46589

Reviewed by Alexey Proskuryakov and Adam Barth.

Going forward, we'd like to get rid of the Noncopyable and FastAllocBase classes. The
reason for this is that the Itanium C++ ABI states that no empty classes of the same type
can be laid out at the same offset in the class. This can result in objects getting larger
which leads to memory regressions. (One example of this is the String class which grew by
sizeof(void*) when both its base class and its first member variable inherited indirectly
from FastAllocBase).

• wtf/Noncopyable.h:

Add a WTF_MAKE_NONCOPYABLE macro and get rid of NoncopyableCustomAllocated.

• runtime/JSCell.h:
• wtf/RefCounted.h:

Don't inherit from NoncopyableCustomAllocated. Instead, use WTF_MAKE_NONCOPYABLE.

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• runtime/JSCell.h (modified) (1 diff)
• wtf/Noncopyable.h (modified) (2 diffs)
• wtf/RefCounted.h (modified) (1 diff)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2010-09-26  Anders Carlsson  <andersca@apple.com>
+
+        Reviewed by Alexey Proskuryakov and Adam Barth.
+
+        Add WTF_MAKE_NONCOPYABLE macro
+        https://bugs.webkit.org/show_bug.cgi?id=46589
+
+        Going forward, we'd like to get rid of the Noncopyable and FastAllocBase classes. The
+        reason for this is that the Itanium C++ ABI states that no empty classes of the same type
+        can be laid out at the same offset in the class. This can result in objects getting larger
+        which leads to memory regressions. (One example of this is the String class which grew by
+        sizeof(void*) when both its base class and its first member variable inherited indirectly
+        from FastAllocBase).
+
+        * wtf/Noncopyable.h:
+        Add a WTF_MAKE_NONCOPYABLE macro and get rid of NoncopyableCustomAllocated.
+        
+        * runtime/JSCell.h:
+        * wtf/RefCounted.h:
+        Don't inherit from NoncopyableCustomAllocated. Instead, use WTF_MAKE_NONCOPYABLE.
+
 2010-09-27  Philippe Normand  <pnormand@igalia.com>
 

trunk/JavaScriptCore/runtime/JSCell.h

@@ -35 +35 @@
 namespace JSC {
 
-    class JSCell : public NoncopyableCustomAllocated {
+    class JSCell {
+        WTF_MAKE_NONCOPYABLE(JSCell);
+
         friend class GetterSetter;
         friend class Heap;

trunk/JavaScriptCore/wtf/Noncopyable.h

@@ -22 +22 @@
 #define WTF_Noncopyable_h
 
+#ifndef __has_feature
+    #define __has_feature(x) 0
+#endif
+
+#if __has_feature(cxx_deleted_functions)
+    #define WTF_MAKE_NONCOPYABLE(ClassName) \
+        _Pragma("clang diagnostic push") \
+        _Pragma("clang diagnostic ignored \"-Wunknown-pragmas\"") \
+        _Pragma("clang diagnostic ignored \"-Wc++0x-extensions\"") \
+        private: \
+            ClassName(const ClassName&) = delete; \
+            ClassName& operator=(const ClassName&) = delete; \
+        _Pragma("clang diagnostic pop")
+#else
+    #define WTF_MAKE_NONCOPYABLE(ClassName) \
+        private: \
+            ClassName(const ClassName&); \
+            ClassName& operator=(const ClassName&);
+#endif
+
 // We don't want argument-dependent lookup to pull in everything from the WTF
 // namespace when you use Noncopyable, so put it in its own namespace.
@@ -37 +57 @@
     };
 
-    class NoncopyableCustomAllocated {
-        NoncopyableCustomAllocated(const NoncopyableCustomAllocated&);
-        NoncopyableCustomAllocated& operator=(const NoncopyableCustomAllocated&);
-    protected:
-        NoncopyableCustomAllocated() { }
-        ~NoncopyableCustomAllocated() { }
-    };
-
 } // namespace WTFNoncopyable
 
 using WTFNoncopyable::Noncopyable;
-using WTFNoncopyable::NoncopyableCustomAllocated;
 
 #endif // WTF_Noncopyable_h

trunk/JavaScriptCore/wtf/RefCounted.h

@@ -146 +146 @@
 };
 
-template<typename T> class RefCountedCustomAllocated : public RefCountedBase, public NoncopyableCustomAllocated {
+template<typename T> class RefCountedCustomAllocated : public RefCountedBase {
+    WTF_MAKE_NONCOPYABLE(RefCountedCustomAllocated);
+
 public:
     void deref()