Speed up construction of basic QVariants

Instead of first creating an initialized Private struct, then overwrite
the member variables, we added an internal constructor that
initializes the private struct sanely.

In the new (inlined, internal) constructor, both the MSB bits in the
bitfield are 0, and since the value of internal meta-type ID is so
low that the two MSB bits should never be set, the compiler can
(hopefully) optimize away the bit-fiddling initialization of the bit-field.

Callgrind shows about 33% speed-up in e.g. QVariant::QVariant(int)

Change-Id: I706773a71c0d8dcbe119ad15411578b81892deb5
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@nokia.com>

1 files changed, 92 insertions, 37 deletions

diff --git a/src/corelib/kernel/qvariant.cpp b/src/corelib/kernel/qvariant.cpp
index ff5a02b380..2f73897df3 100644
--- a/src/corelib/kernel/qvariant.cpp
+++ b/src/corelib/kernel/qvariant.cpp
@@ -1431,71 +1431,126 @@ QVariant::QVariant(int typeId, const void *copy, uint flags)
 }
 
 QVariant::QVariant(int val)
-{ d.is_null = false; d.type = Int; d.data.i = val; }
+    : d(Int)
+{ d.data.i = val; }
 QVariant::QVariant(uint val)
-{ d.is_null = false; d.type = UInt; d.data.u = val; }
+    : d(UInt)
+{ d.data.u = val; }
 QVariant::QVariant(qlonglong val)
-{ d.is_null = false; d.type = LongLong; d.data.ll = val; }
+    : d(LongLong)
+{ d.data.ll = val; }
 QVariant::QVariant(qulonglong val)
-{ d.is_null = false; d.type = ULongLong; d.data.ull = val; }
+    : d(ULongLong)
+{ d.data.ull = val; }
 QVariant::QVariant(bool val)
-{ d.is_null = false; d.type = Bool; d.data.b = val; }
+    : d(Bool)
+{ d.data.b = val; }
 QVariant::QVariant(double val)
-{ d.is_null = false; d.type = Double; d.data.d = val; }
+    : d(Double)
+{ d.data.d = val; }
 
 QVariant::QVariant(const QByteArray &val)
-{ d.is_null = false; d.type = ByteArray; v_construct<QByteArray>(&d, val); }
+    : d(ByteArray)
+{ v_construct<QByteArray>(&d, val); }
 QVariant::QVariant(const QBitArray &val)
-{ d.is_null = false; d.type = BitArray; v_construct<QBitArray>(&d, val);  }
+    : d(BitArray)
+{ v_construct<QBitArray>(&d, val);  }
 QVariant::QVariant(const QString &val)
-{ d.is_null = false; d.type = String; v_construct<QString>(&d, val);  }
+    : d(String)
+{ v_construct<QString>(&d, val);  }
 QVariant::QVariant(QChar val)
-{ d.is_null = false; d.type = Char; v_construct<QChar>(&d, val);  }
+    : d(Char)
+{ v_construct<QChar>(&d, val);  }
 QVariant::QVariant(QLatin1String val)
-{ QString str(val); d.is_null = false; d.type = String; v_construct<QString>(&d, str); }
+    : d(String)
+{ v_construct<QString>(&d, val); }
 QVariant::QVariant(const QStringList &val)
-{ d.is_null = false; d.type = StringList; v_construct<QStringList>(&d, val); }
+    : d(StringList)
+{ v_construct<QStringList>(&d, val); }
 
 QVariant::QVariant(const QDate &val)
-{ d.is_null = false; d.type = Date; v_construct<QDate>(&d, val); }
+    : d(Date)
+{ v_construct<QDate>(&d, val); }
 QVariant::QVariant(const QTime &val)
-{ d.is_null = false; d.type = Time; v_construct<QTime>(&d, val); }
+    : d(Time)
+{ v_construct<QTime>(&d, val); }
 QVariant::QVariant(const QDateTime &val)
-{ d.is_null = false; d.type = DateTime; v_construct<QDateTime>(&d, val); }
+    : d(DateTime)
+{ v_construct<QDateTime>(&d, val); }
 #ifndef QT_BOOTSTRAPPED
 QVariant::QVariant(const QEasingCurve &val)
-{ d.is_null = false; d.type = EasingCurve; v_construct<QEasingCurve>(&d, val); }
+    : d(EasingCurve)
+{ v_construct<QEasingCurve>(&d, val); }
 #endif
 QVariant::QVariant(const QList<QVariant> &list)
-{ d.is_null = false; d.type = List; v_construct<QVariantList>(&d, list); }
+    : d(List)
+{ v_construct<QVariantList>(&d, list); }
 QVariant::QVariant(const QMap<QString, QVariant> &map)
-{ d.is_null = false; d.type = Map; v_construct<QVariantMap>(&d, map); }
+    : d(Map)
+{ v_construct<QVariantMap>(&d, map); }
 QVariant::QVariant(const QHash<QString, QVariant> &hash)
-{ d.is_null = false; d.type = Hash; v_construct<QVariantHash>(&d, hash); }
+    : d(Hash)
+{ v_construct<QVariantHash>(&d, hash); }
 #ifndef QT_NO_GEOM_VARIANT
-QVariant::QVariant(const QPoint &pt) { d.is_null = false; d.type = Point; v_construct<QPoint>(&d, pt); }
-QVariant::QVariant(const QPointF &pt) { d.is_null = false; d.type = PointF; v_construct<QPointF>(&d, pt); }
-QVariant::QVariant(const QRectF &r) { d.is_null = false; d.type = RectF; v_construct<QRectF>(&d, r); }
-QVariant::QVariant(const QLineF &l) { d.is_null = false; d.type = LineF; v_construct<QLineF>(&d, l); }
-QVariant::QVariant(const QLine &l) { d.is_null = false; d.type = Line; v_construct<QLine>(&d, l); }
-QVariant::QVariant(const QRect &r) { d.is_null = false; d.type = Rect; v_construct<QRect>(&d, r); }
-QVariant::QVariant(const QSize &s) { d.is_null = false; d.type = Size; v_construct<QSize>(&d, s); }
-QVariant::QVariant(const QSizeF &s) { d.is_null = false; d.type = SizeF; v_construct<QSizeF>(&d, s); }
+QVariant::QVariant(const QPoint &pt)
+    : d(Point)
+{ v_construct<QPoint>(&d, pt); }
+QVariant::QVariant(const QPointF &pt)
+    : d(PointF)
+{ v_construct<QPointF>(&d, pt); }
+QVariant::QVariant(const QRectF &r)
+    : d(RectF)
+{ v_construct<QRectF>(&d, r); }
+QVariant::QVariant(const QLineF &l)
+    : d(LineF)
+{ v_construct<QLineF>(&d, l); }
+QVariant::QVariant(const QLine &l)
+    : d(Line)
+{ v_construct<QLine>(&d, l); }
+QVariant::QVariant(const QRect &r)
+    : d(Rect)
+{ v_construct<QRect>(&d, r); }
+QVariant::QVariant(const QSize &s)
+    : d(Size)
+{ v_construct<QSize>(&d, s); }
+QVariant::QVariant(const QSizeF &s)
+    : d(SizeF)
+{ v_construct<QSizeF>(&d, s); }
 #endif
 #ifndef QT_BOOTSTRAPPED
-QVariant::QVariant(const QUrl &u) { d.is_null = false; d.type = Url; v_construct<QUrl>(&d, u); }
+QVariant::QVariant(const QUrl &u)
+    : d(Url)
+{ v_construct<QUrl>(&d, u); }
 #endif
-QVariant::QVariant(const QLocale &l) { d.is_null = false; d.type = Locale; v_construct<QLocale>(&d, l); }
+QVariant::QVariant(const QLocale &l)
+    : d(Locale)
+{ v_construct<QLocale>(&d, l); }
 #ifndef QT_NO_REGEXP
-QVariant::QVariant(const QRegExp &regExp) { d.is_null = false; d.type = RegExp; v_construct<QRegExp>(&d, regExp); }
+QVariant::QVariant(const QRegExp &regExp)
+    : d(RegExp)
+{ v_construct<QRegExp>(&d, regExp); }
 #ifndef QT_BOOTSTRAPPED
-QVariant::QVariant(const QRegularExpression &re) { d.is_null = false; d.type = QMetaType::QRegularExpression; v_construct<QRegularExpression>(&d, re); }
-QVariant::QVariant(const QUuid &uuid) { d.is_null = false; d.type = QMetaType::QUuid; v_construct<QUuid>(&d, uuid); }
-QVariant::QVariant(const QModelIndex &modelIndex) { d.is_null = false; d.type = QMetaType::QModelIndex; v_construct<QModelIndex>(&d, modelIndex); }
-QVariant::QVariant(const QJsonValue &jsonValue) { d.is_null = false; d.type = QMetaType::QJsonValue; v_construct<QJsonValue>(&d, jsonValue); }
-QVariant::QVariant(const QJsonObject &jsonObject) { d.is_null = false; d.type = QMetaType::QJsonObject; v_construct<QJsonObject>(&d, jsonObject); }
-QVariant::QVariant(const QJsonArray &jsonArray) { d.is_null = false; d.type = QMetaType::QJsonArray; v_construct<QJsonArray>(&d, jsonArray); }
-QVariant::QVariant(const QJsonDocument &jsonDocument) { d.is_null = false; d.type = QMetaType::QJsonDocument; v_construct<QJsonDocument>(&d, jsonDocument); }
+QVariant::QVariant(const QRegularExpression &re)
+    : d(RegularExpression)
+{ v_construct<QRegularExpression>(&d, re); }
+QVariant::QVariant(const QUuid &uuid)
+    : d(Uuid)
+{ v_construct<QUuid>(&d, uuid); }
+QVariant::QVariant(const QModelIndex &modelIndex)
+    : d(ModelIndex)
+{ v_construct<QModelIndex>(&d, modelIndex); }
+QVariant::QVariant(const QJsonValue &jsonValue)
+    : d(QMetaType::QJsonValue)
+{ v_construct<QJsonValue>(&d, jsonValue); }
+QVariant::QVariant(const QJsonObject &jsonObject)
+    : d(QMetaType::QJsonObject)
+{ v_construct<QJsonObject>(&d, jsonObject); }
+QVariant::QVariant(const QJsonArray &jsonArray)
+    : d(QMetaType::QJsonArray)
+{ v_construct<QJsonArray>(&d, jsonArray); }
+QVariant::QVariant(const QJsonDocument &jsonDocument)
+    : d(QMetaType::QJsonDocument)
+{ v_construct<QJsonDocument>(&d, jsonDocument); }
 #endif // QT_BOOTSTRAPPED
 #endif // QT_NO_REGEXP