Reduce code bloat, by cleaning up QMetaTypeFunctionHelper

Create and Delete wrappers are not necessary, because they can be
easily simulated with Construct and Destruct. This change removes
redundant function wrappers and a bit of over-optimized code. Gain is
quite big:

Before:
   text    data     bss     dec     hex filename
5366008   47460   14904 5428372  52d494 libQt5Core.so.5.5.0
 505578    7060    2124  514762   7daca libQt5DBus.so.5.5.0
5591079  134656    6728 5732463  57786f libQt5Gui.so.5.5.0
1398785   31676    2576 1433037  15ddcd libQt5Network.so.5.5.0
6642431  220952    2536 6865919  68c3ff libQt5Widgets.so.5.5.0

After:
   text    data     bss     dec     hex filename
5342559   47460   14904 5404923  5278fb libQt5Core.so.5.5.0
 496025    7068    2124  505217   7b581 libQt5DBus.so.5.5.0
5579291  134272    6728 5720291  5748e3 libQt5Gui.so.5.5.0
1389461   31676    2576 1423713  15b961 libQt5Network.so.5.5.0
6637139  220952    2536 6860627  68af53 libQt5Widgets.so.5.5.0

Cost of the change, is moved to CPU while calling QMetaType create()
and destroy(), these two functions became a bit slower. The cost should
not be visible, because they call operator new anyway.

Change-Id: I34fd410343377d9c29925675d7da8172bfda9ce6
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 13 insertions, 12 deletions

diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h
index dc7e7e0395..e89b3affc6 100644
--- a/src/corelib/kernel/qmetatype.h
+++ b/src/corelib/kernel/qmetatype.h
@@ -471,6 +471,11 @@ public:
                             int size,
                             QMetaType::TypeFlags flags,
                             const QMetaObject *metaObject);
+    static int registerNormalizedType(const QT_PREPEND_NAMESPACE(QByteArray) &normalizedTypeName, Destructor destructor,
+                            Constructor constructor,
+                            int size,
+                            QMetaType::TypeFlags flags,
+                            const QMetaObject *metaObject);
     static int registerTypedef(const char *typeName, int aliasId);
     static int registerNormalizedTypedef(const QT_PREPEND_NAMESPACE(QByteArray) &normalizedTypeName, int aliasId);
     static int type(const char *typeName);
@@ -668,8 +673,8 @@ public:
     static void unregisterConverterFunction(int from, int to);
 private:
 
-    Creator m_creator;
-    Deleter m_deleter;
+    Creator m_creator_unused;
+    Deleter m_deleter_unused;
     SaveOperator m_saveOp;
     LoadOperator m_loadOp;
     Constructor m_constructor;
@@ -1618,8 +1623,6 @@ int qRegisterNormalizedMetaType(const QT_PREPEND_NAMESPACE(QByteArray) &normaliz
         flags |= QMetaType::WasDeclaredAsMetaType;
 
     const int id = QMetaType::registerNormalizedType(normalizedTypeName,
-                                   QtMetaTypePrivate::QMetaTypeFunctionHelper<T>::Delete,
-                                   QtMetaTypePrivate::QMetaTypeFunctionHelper<T>::Create,
                                    QtMetaTypePrivate::QMetaTypeFunctionHelper<T>::Destruct,
                                    QtMetaTypePrivate::QMetaTypeFunctionHelper<T>::Construct,
                                    int(sizeof(T)),
@@ -1988,8 +1991,8 @@ inline QMetaType::QMetaType(const ExtensionFlag extensionFlags, const QMetaTypeI
                             uint theTypeFlags,
                             int typeId,
                             const QMetaObject *_metaObject)
-    : m_creator(creator)
-    , m_deleter(deleter)
+    : m_creator_unused(creator)
+    , m_deleter_unused(deleter)
     , m_saveOp(saveOp)
     , m_loadOp(loadOp)
     , m_constructor(constructor)
@@ -2023,16 +2026,14 @@ inline bool QMetaType::isRegistered() const
 
 inline void *QMetaType::create(const void *copy) const
 {
-    if (Q_UNLIKELY(isExtended(CreateEx)))
-        return createExtended(copy);
-    return m_creator(copy);
+    // ### TODO Qt6 remove the extension
+    return createExtended(copy);
 }
 
 inline void QMetaType::destroy(void *data) const
 {
-    if (Q_UNLIKELY(isExtended(DestroyEx)))
-        return destroyExtended(data);
-    m_deleter(data);
+    // ### TODO Qt6 remove the extension
+    destroyExtended(data);
 }
 
 inline void *QMetaType::construct(void *where, const void *copy) const