QtWidgets: use Q_UNLIKELY for every qWarning() (2)

If, after checking a condition, we issue a qWarning(),
by definition that check is unlikely to be true.

Tell the compiler so it can move the error handling
code out of the normal code path to increase the
effective icache size.

This change contains the changes to the accessible/,
effects/, kernel/, styles/ and itemviews/ subdirs.

Moved conditional code around where possible so that
we could always use Q_UNLIKELY, instead of having to
revert to Q_LIKELY here and there.

In QWidgetPrivate::setWindowModified_helper(), as a
drive-by, I swapped the evaluation order of an
&&-expression (newly wrapped in Q_UNLIKELY) to be
more readable and more efficient (cheaper check
first) at the same time.

In qDraw* (qdrawutil.cpp), simplified boolean
expressions (sometimes by skipping re-checking
conditions already checked in a previous guard clause).

Change-Id: I58be22be0a33522c2629a66c2f6c795771a99f3f
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

src/widgets/accessible/itemviews.cpp

@@ -132,7 +132,7 @@ QAccessibleInterface *QAccessibleTable::cellAt(int row, int column) const
         return 0;
     Q_ASSERT(role() != QAccessible::Tree);
     QModelIndex index = view()->model()->index(row, column, view()->rootIndex());
-    if (!index.isValid()) {
+    if (Q_UNLIKELY(!index.isValid())) {
         qWarning() << "QAccessibleTable::cellAt: invalid index: " << index << " for " << view();
         return 0;
     }
@@ -505,7 +505,7 @@ QAccessibleInterface *QAccessibleTable::child(int logicalIndex) const
 
     if (!iface) {
         QModelIndex index = view()->model()->index(row, column, view()->rootIndex());
-        if (!index.isValid()) {
+        if (Q_UNLIKELY(!index.isValid())) {
             qWarning() << "QAccessibleTable::child: Invalid index at: " << row << column;
             return 0;
         }
@@ -666,7 +666,7 @@ QModelIndex QAccessibleTree::indexFromLogical(int row, int column) const
         return QModelIndex();
 
     const QTreeView *treeView = qobject_cast<const QTreeView*>(view());
-    if ((row < 0) || (column < 0) || (treeView->d_func()->viewItems.count() <= row)) {
+    if (Q_UNLIKELY(row < 0 || column < 0 || treeView->d_func()->viewItems.count() <= row)) {
         qWarning() << "QAccessibleTree::indexFromLogical: invalid index: " << row << column << " for " << treeView;
         return QModelIndex();
     }
@@ -776,7 +776,7 @@ int QAccessibleTree::indexOfChild(const QAccessibleInterface *iface) const
 QAccessibleInterface *QAccessibleTree::cellAt(int row, int column) const
 {
     QModelIndex index = indexFromLogical(row, column);
-    if (!index.isValid()) {
+    if (Q_UNLIKELY(!index.isValid())) {
         qWarning() << "Requested invalid tree cell: " << row << column;
         return 0;
     }
@@ -835,7 +835,7 @@ bool QAccessibleTree::selectRow(int row)
 QAccessibleTableCell::QAccessibleTableCell(QAbstractItemView *view_, const QModelIndex &index_, QAccessible::Role role_)
     : /* QAccessibleSimpleEditableTextInterface(this), */ view(view_), m_index(index_), m_role(role_)
 {
-    if (!index_.isValid())
+    if (Q_UNLIKELY(!index_.isValid()))
         qWarning() << "QAccessibleTableCell::QAccessibleTableCell with invalid index: " << index_;
 }
 

src/widgets/accessible/qaccessiblewidget.cpp

@@ -274,7 +274,7 @@ public:
 void QAccessibleWidget::addControllingSignal(const QString &signal)
 {
     QByteArray s = QMetaObject::normalizedSignature(signal.toLatin1());
-    if (object()->metaObject()->indexOfSignal(s) < 0)
+    if (Q_UNLIKELY(object()->metaObject()->indexOfSignal(s) < 0))
         qWarning("Signal %s unknown in %s", s.constData(), object()->metaObject()->className());
     d->primarySignals << QLatin1String(s);
 }

src/widgets/accessible/qaccessiblewidgets.cpp

@@ -282,7 +282,7 @@ void QAccessibleTextEdit::scrollToSubstring(int startIndex, int endIndex)
              r.y() + edit->verticalScrollBar()->value());
 
     // E V I L, but ensureVisible is not public
-    if (!QMetaObject::invokeMethod(edit, "_q_ensureVisible", Q_ARG(QRectF, r)))
+    if (Q_UNLIKELY(!QMetaObject::invokeMethod(edit, "_q_ensureVisible", Q_ARG(QRectF, r))))
         qWarning("AccessibleTextEdit::scrollToSubstring failed!");
 }
 

src/widgets/effects/qgraphicseffect.cpp

@@ -316,8 +316,8 @@ QPixmap QGraphicsEffectSource::pixmap(Qt::CoordinateSystem system, QPoint *offse
         return pixmapItem->pixmap();
     }
 
-    if (system == Qt::DeviceCoordinates && item
+    if (Q_UNLIKELY(system == Qt::DeviceCoordinates && item &&
-        && !static_cast<const QGraphicsItemEffectSourcePrivate *>(d_func())->info) {
+                   !static_cast<const QGraphicsItemEffectSourcePrivate *>(d_func())->info)) {
         qWarning("QGraphicsEffectSource::pixmap: Not yet implemented, lacking device context");
         return QPixmap();
     }

src/widgets/itemviews/qabstractitemview.cpp

@@ -758,7 +758,7 @@ void QAbstractItemView::setSelectionModel(QItemSelectionModel *selectionModel)
     Q_ASSERT(selectionModel);
     Q_D(QAbstractItemView);
 
-    if (selectionModel->model() != d->model) {
+    if (Q_UNLIKELY(selectionModel->model() != d->model)) {
         qWarning("QAbstractItemView::setSelectionModel() failed: "
                  "Trying to set a selection model, which works on "
                  "a different model than the view.");
@@ -1113,7 +1113,7 @@ void QAbstractItemView::reset()
 void QAbstractItemView::setRootIndex(const QModelIndex &index)
 {
     Q_D(QAbstractItemView);
-    if (index.isValid() && index.model() != d->model) {
+    if (Q_UNLIKELY(index.isValid() && index.model() != d->model)) {
         qWarning("QAbstractItemView::setRootIndex failed : index must be from the currently set model");
         return;
     }
@@ -1166,9 +1166,9 @@ void QAbstractItemView::selectAll()
 void QAbstractItemView::edit(const QModelIndex &index)
 {
     Q_D(QAbstractItemView);
-    if (!d->isIndexValid(index))
+    if (Q_UNLIKELY(!d->isIndexValid(index)))
         qWarning("edit: index was invalid");
-    if (!edit(index, AllEditTriggers, 0))
+    if (Q_UNLIKELY(!edit(index, AllEditTriggers, 0)))
         qWarning("edit: editing failed");
 }
 

src/widgets/itemviews/qdirmodel.cpp

@@ -1022,7 +1022,7 @@ bool QDirModel::rmdir(const QModelIndex &index)
         return false;
 
     QDirModelPrivate::QDirNode *n = d_func()->node(index);
-    if (!n->info.isDir()) {
+    if (Q_UNLIKELY(!n->info.isDir())) {
         qWarning("rmdir: the node is not a directory");
         return false;
     }
@@ -1172,7 +1172,7 @@ QDirModelPrivate::QDirNode *QDirModelPrivate::node(int row, QDirNode *parent) co
     if (isDir && !p->populated)
         populate(p); // will also resolve symlinks
 
-    if (row >= p->children.count()) {
+    if (Q_UNLIKELY(row >= p->children.count())) {
         qWarning("node: the row does not exist");
         return 0;
     }

src/widgets/itemviews/qlistview.cpp

@@ -392,7 +392,7 @@ int QListView::spacing() const
 void QListView::setBatchSize(int batchSize)
 {
     Q_D(QListView);
-    if (batchSize <= 0) {
+    if (Q_UNLIKELY(batchSize <= 0)) {
         qWarning("Invalid batchSize (%d)", batchSize);
         return;
     }

src/widgets/itemviews/qtableview.cpp

@@ -669,7 +669,7 @@ void QTableViewPrivate::trimHiddenSelections(QItemSelectionRange *range) const
 */
 void QTableViewPrivate::setSpan(int row, int column, int rowSpan, int columnSpan)
 {
-    if (row < 0 || column < 0 || rowSpan <= 0 || columnSpan <= 0) {
+    if (Q_UNLIKELY(row < 0 || column < 0 || rowSpan <= 0 || columnSpan <= 0)) {
         qWarning("QTableView::setSpan: invalid span given: (%d, %d, %d, %d)",
                  row, column, rowSpan, columnSpan);
         return;
@@ -688,7 +688,7 @@ void QTableViewPrivate::setSpan(int row, int column, int rowSpan, int columnSpan
         sp->m_right = column + columnSpan - 1;
         spans.updateSpan(sp, old_height);
         return;
-    } else if (rowSpan == 1 && columnSpan == 1) {
+    } else if (Q_UNLIKELY(rowSpan == 1 && columnSpan == 1)) {
         qWarning("QTableView::setSpan: single cell span won't be added");
         return;
     }

src/widgets/itemviews/qtablewidget.cpp

@@ -1958,7 +1958,7 @@ void QTableWidget::setItem(int row, int column, QTableWidgetItem *item)
 {
     Q_D(QTableWidget);
     if (item) {
-        if (item->view != 0) {
+        if (Q_UNLIKELY(item->view)) {
             qWarning("QTableWidget: cannot insert an item that is already owned by another QTableWidget");
         } else {
             item->view = this;

src/widgets/itemviews/qtreewidget.cpp

@@ -3280,14 +3280,14 @@ QMimeData *QTreeWidget::mimeData(const QList<QTreeWidgetItem*> items) const
         QList<QModelIndex> indexes;
         for (int i = 0; i < items.count(); ++i) {
             QTreeWidgetItem *item = items.at(i);
-            if (!item) {
+            if (Q_UNLIKELY(!item)) {
                 qWarning("QTreeWidget::mimeData: Null-item passed");
                 return 0;
             }
 
             for (int c = 0; c < item->values.count(); ++c) {
                 const QModelIndex index = indexFromItem(item, c);
-                if (!index.isValid()) {
+                if (Q_UNLIKELY(!index.isValid())) {
                     qWarning() << "QTreeWidget::mimeData: No index associated with item :" << item;
                     return 0;
                 }

src/widgets/kernel/qaction.cpp

@@ -45,7 +45,7 @@
 #include <private/qmenu_p.h>
 
 #define QAPP_CHECK(functionName) \
-    if (!qApp) { \
+    if (Q_UNLIKELY(!qApp)) { \
         qWarning("QAction: Initialize QApplication before calling '" functionName "'."); \
         return; \
     }

src/widgets/kernel/qapplication.cpp

@@ -1368,7 +1368,7 @@ int QApplication::colorSpec()
 
 void QApplication::setColorSpec(int spec)
 {
-    if (qApp)
+    if (Q_UNLIKELY(qApp))
         qWarning("QApplication::setColorSpec: This function must be "
                  "called before the QApplication object is created");
     QApplicationPrivate::app_cspec = spec;
@@ -2485,7 +2485,7 @@ bool QApplicationPrivate::isBlockedByModal(QWidget *widget)
 bool QApplicationPrivate::isWindowBlocked(QWindow *window, QWindow **blockingWindow) const
 {
     QWindow *unused = 0;
-    if (!window) {
+    if (Q_UNLIKELY(!window)) {
         qWarning().nospace() << "window == 0 passed.";
         return false;
     }
@@ -3007,7 +3007,7 @@ bool QApplication::notify(QObject *receiver, QEvent *e)
     if (QApplicationPrivate::is_app_closing)
         return true;
 
-    if (receiver == 0) {                        // serious error
+    if (Q_UNLIKELY(!receiver)) {                        // serious error
         qWarning("QApplication::notify: Unexpected null receiver");
         return true;
     }
@@ -3256,7 +3256,7 @@ bool QApplication::notify(QObject *receiver, QEvent *e)
                         QObject *obj = d->extraData->eventFilters.at(i);
                         if (!obj)
                             continue;
-                        if (obj->d_func()->threadData != w->d_func()->threadData) {
+                        if (Q_UNLIKELY(obj->d_func()->threadData != w->d_func()->threadData)) {
                             qWarning("QApplication: Object event filter cannot be in a different thread.");
                             continue;
                         }

src/widgets/kernel/qdesktopwidget.cpp

@@ -48,7 +48,7 @@ int QDesktopScreenWidget::screenNumber() const
 
 const QRect QDesktopWidget::screenGeometry(const QWidget *widget) const
 {
-    if (!widget) {
+    if (Q_UNLIKELY(!widget)) {
         qWarning("QDesktopWidget::screenGeometry(): Attempt "
                  "to get the screen geometry of a null widget");
         return QRect();
@@ -61,7 +61,7 @@ const QRect QDesktopWidget::screenGeometry(const QWidget *widget) const
 
 const QRect QDesktopWidget::availableGeometry(const QWidget *widget) const
 {
-    if (!widget) {
+    if (Q_UNLIKELY(!widget)) {
         qWarning("QDesktopWidget::availableGeometry(): Attempt "
                  "to get the available geometry of a null widget");
         return QRect();

src/widgets/kernel/qformlayout.cpp

@@ -945,7 +945,7 @@ void QFormLayoutPrivate::setItem(int row, QFormLayout::ItemRole role, QLayoutIte
 {
     const bool fullRow = role == QFormLayout::SpanningRole;
     const int column =  role == QFormLayout::SpanningRole ? 1 : static_cast<int>(role);
-    if (uint(row) >= uint(m_matrix.rowCount()) || uint(column) > 1U) {
+    if (Q_UNLIKELY(uint(row) >= uint(m_matrix.rowCount()) || uint(column) > 1U)) {
         qWarning("QFormLayoutPrivate::setItem: Invalid cell (%d, %d)", row, column);
         return;
     }
@@ -953,7 +953,7 @@ void QFormLayoutPrivate::setItem(int row, QFormLayout::ItemRole role, QLayoutIte
     if (!item)
         return;
 
-    if (m_matrix(row, column)) {
+    if (Q_UNLIKELY(m_matrix(row, column))) {
         qWarning("QFormLayoutPrivate::setItem: Cell (%d, %d) already occupied", row, column);
         return;
     }
@@ -1000,7 +1000,7 @@ QLayoutItem* QFormLayoutPrivate::replaceAt(int index, QLayoutItem *newitem)
     if (!newitem)
         return 0;
     const int storageIndex = storageIndexFromLayoutItem(m_matrix, m_things.value(index));
-    if (storageIndex == -1) {
+    if (Q_UNLIKELY(storageIndex == -1)) {
         // ### Qt6 - fix warning too when this class becomes public
         qWarning("QFormLayoutPrivate::replaceAt: Invalid index %d", index);
         return 0;
@@ -1414,7 +1414,7 @@ QLayoutItem *QFormLayout::takeAt(int index)
     Q_D(QFormLayout);
 
     const int storageIndex = storageIndexFromLayoutItem(d->m_matrix, d->m_things.value(index));
-    if (storageIndex == -1) {
+    if (Q_UNLIKELY(storageIndex == -1)) {
         qWarning("QFormLayout::takeAt: Invalid index %d", index);
         return 0;
     }

src/widgets/kernel/qgesturemanager.cpp

@@ -117,7 +117,7 @@ QGestureManager::~QGestureManager()
 Qt::GestureType QGestureManager::registerGestureRecognizer(QGestureRecognizer *recognizer)
 {
     QGesture *dummy = recognizer->create(0);
-    if (!dummy) {
+    if (Q_UNLIKELY(!dummy)) {
         qWarning("QGestureManager::registerGestureRecognizer: "
                  "the recognizer fails to create a gesture object, skipping registration.");
         return Qt::GestureType(0);
@@ -640,17 +640,17 @@ void QGestureManager::deliverEvents(const QSet<QGesture *> &gestures,
         Q_ASSERT(gestureType != Qt::CustomGesture);
         Q_UNUSED(gestureType);
 
-        if (target) {
+        if (Q_UNLIKELY(!target)) {
+            qCDebug(lcGestureManager) << "QGestureManager::deliverEvent: could not find the target for gesture"
+                    << gesture->gestureType();
+            qWarning("QGestureManager::deliverEvent: could not find the target for gesture");
+            undeliveredGestures->insert(gesture);
+        } else {
             if (gesture->state() == Qt::GestureStarted) {
                 startedGestures.insert(gesture);
             } else {
                 normalStartedGestures[target].append(gesture);
             }
-        } else {
-            qCDebug(lcGestureManager) << "QGestureManager::deliverEvent: could not find the target for gesture"
-                    << gesture->gestureType();
-            qWarning("QGestureManager::deliverEvent: could not find the target for gesture");
-            undeliveredGestures->insert(gesture);
         }
     }
 

src/widgets/kernel/qgridlayout.cpp

@@ -557,9 +557,9 @@ void QGridLayoutPrivate::add(QGridBox *box, int row, int col)
 
 void QGridLayoutPrivate::add(QGridBox *box, int row1, int row2, int col1, int col2)
 {
-    if (row2 >= 0 && row2 < row1)
+    if (Q_UNLIKELY(row2 >= 0 && row2 < row1))
         qWarning("QGridLayout: Multi-cell fromRow greater than toRow");
-    if (col2 >= 0 && col2 < col1)
+    if (Q_UNLIKELY(col2 >= 0 && col2 < col1))
         qWarning("QGridLayout: Multi-cell fromCol greater than toCol");
     if (row1 == row2 && col1 == col2) {
         add(box, row1, col1);
@@ -1435,7 +1435,7 @@ void QGridLayout::addWidget(QWidget *widget, int row, int column, Qt::Alignment
     Q_D(QGridLayout);
     if (!d->checkWidget(widget))
         return;
-    if (row < 0 || column < 0) {
+    if (Q_UNLIKELY(row < 0 || column < 0)) {
         qWarning("QGridLayout: Cannot add %s/%s to %s/%s at row %d column %d",
                  widget->metaObject()->className(), widget->objectName().toLocal8Bit().data(),
                  metaObject()->className(), objectName().toLocal8Bit().data(), row, column);

src/widgets/kernel/qlayout.cpp

@@ -129,7 +129,7 @@ QLayout::QLayout(QLayoutPrivate &dd, QLayout *lay, QWidget *w)
     if (lay) {
         lay->addItem(this);
     } else if (w) {
-        if (w->layout()) {
+        if (Q_UNLIKELY(w->layout())) {
             qWarning("QLayout: Attempting to add QLayout \"%ls\" to %s \"%ls\", which"
                      " already has a layout",
                      qUtf16Printable(QObject::objectName()), w->metaObject()->className(),
@@ -469,7 +469,7 @@ QWidget *QLayout::parentWidget() const
     if (!d->topLevel) {
         if (parent()) {
             QLayout *parentLayout = qobject_cast<QLayout*>(parent());
-            if (!parentLayout) {
+            if (Q_UNLIKELY(!parentLayout)) {
                 qWarning("QLayout::parentWidget: A layout can only have another layout as a parent.");
                 return 0;
             }
@@ -776,7 +776,7 @@ QLayout::~QLayout()
 */
 void QLayout::addChildLayout(QLayout *l)
 {
-    if (l->parent()) {
+    if (Q_UNLIKELY(l->parent())) {
         qWarning("QLayout::addChildLayout: layout \"%ls\" already has a parent",
                  qUtf16Printable(l->objectName()));
         return;
@@ -826,7 +826,7 @@ void QLayoutPrivate::reparentChildWidgets(QWidget *mw)
         if (QWidget *w = item->widget()) {
             QWidget *pw = w->parentWidget();
 #ifdef QT_DEBUG
-            if (pw && pw != mw && layoutDebug()) {
+            if (Q_UNLIKELY(pw && pw != mw && layoutDebug())) {
                 qWarning("QLayout::addChildLayout: widget %s \"%ls\" in wrong parent; moved to correct parent",
                          w->metaObject()->className(), qUtf16Printable(w->objectName()));
             }
@@ -849,12 +849,12 @@ void QLayoutPrivate::reparentChildWidgets(QWidget *mw)
 bool QLayoutPrivate::checkWidget(QWidget *widget) const
 {
     Q_Q(const QLayout);
-    if (!widget) {
+    if (Q_UNLIKELY(!widget)) {
         qWarning("QLayout: Cannot add a null widget to %s/%ls", q->metaObject()->className(),
                   qUtf16Printable(q->objectName()));
         return false;
     }
-    if (widget == q->parentWidget()) {
+    if (Q_UNLIKELY(widget == q->parentWidget())) {
         qWarning("QLayout: Cannot add parent widget %s/%ls to its child layout %s/%ls",
                   widget->metaObject()->className(), qUtf16Printable(widget->objectName()),
                   q->metaObject()->className(), qUtf16Printable(q->objectName()));
@@ -870,12 +870,12 @@ bool QLayoutPrivate::checkWidget(QWidget *widget) const
 bool QLayoutPrivate::checkLayout(QLayout *otherLayout) const
 {
     Q_Q(const QLayout);
-    if (!otherLayout) {
+    if (Q_UNLIKELY(!otherLayout)) {
         qWarning("QLayout: Cannot add a null layout to %s/%ls",
                  q->metaObject()->className(), qUtf16Printable(q->objectName()));
         return false;
     }
-    if (otherLayout == q) {
+    if (Q_UNLIKELY(otherLayout == q)) {
         qWarning("QLayout: Cannot add layout %s/%ls to itself",
                  q->metaObject()->className(), qUtf16Printable(q->objectName()));
         return false;
@@ -902,7 +902,7 @@ void QLayout::addChildWidget(QWidget *w)
         QLayout *l = pw->layout();
         if (l && removeWidgetRecursively(l, w)) {
 #ifdef QT_DEBUG
-            if (layoutDebug())
+            if (Q_UNLIKELY(layoutDebug()))
                 qWarning("QLayout::addChildWidget: %s \"%ls\" is already in a layout; moved to new layout",
                          w->metaObject()->className(), qUtf16Printable(w->objectName()));
 #endif
@@ -910,7 +910,7 @@ void QLayout::addChildWidget(QWidget *w)
     }
     if (pw && mw && pw != mw) {
 #ifdef QT_DEBUG
-            if (layoutDebug())
+            if (Q_UNLIKELY(layoutDebug()))
                 qWarning("QLayout::addChildWidget: %s \"%ls\" in wrong parent; moved to correct parent",
                          w->metaObject()->className(), qUtf16Printable(w->objectName()));
 #endif
@@ -1064,7 +1064,7 @@ bool QLayout::activate()
     if (d->activated)
         return false;
     QWidget *mw = static_cast<QWidget*>(parent());
-    if (mw == 0) {
+    if (Q_UNLIKELY(!mw)) {
         qWarning("QLayout::activate: %s \"%ls\" does not have a main widget",
                  metaObject()->className(), qUtf16Printable(objectName()));
         return false;

src/widgets/kernel/qopenglwidget.cpp

@@ -740,7 +740,7 @@ void QOpenGLWidgetPrivate::initialize()
     // texture usable by the underlying window's backingstore.
     QWidget *tlw = q->window();
     QOpenGLContext *shareContext = get(tlw)->shareContext();
-    if (!shareContext) {
+    if (Q_UNLIKELY(!shareContext)) {
         qWarning("QOpenGLWidget: Cannot be used without a context shared with the toplevel.");
         return;
     }
@@ -756,7 +756,7 @@ void QOpenGLWidgetPrivate::initialize()
     ctx->setShareContext(shareContext);
     ctx->setFormat(requestedFormat);
     ctx->setScreen(shareContext->screen());
-    if (!ctx->create()) {
+    if (Q_UNLIKELY(!ctx->create())) {
         qWarning("QOpenGLWidget: Failed to create context");
         return;
     }
@@ -782,7 +782,7 @@ void QOpenGLWidgetPrivate::initialize()
     surface->setScreen(ctx->screen());
     surface->create();
 
-    if (!ctx->makeCurrent(surface)) {
+    if (Q_UNLIKELY(!ctx->makeCurrent(surface))) {
         qWarning("QOpenGLWidget: Failed to make context current");
         return;
     }
@@ -915,10 +915,10 @@ QOpenGLWidget::QOpenGLWidget(QWidget *parent, Qt::WindowFlags f)
     : QWidget(*(new QOpenGLWidgetPrivate), parent, f)
 {
     Q_D(QOpenGLWidget);
-    if (QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::RasterGLSurface))
+    if (Q_UNLIKELY(!QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::RasterGLSurface)))
-        d->setRenderToTexture();
-    else
         qWarning("QOpenGLWidget is not supported on this platform.");
+    else
+        d->setRenderToTexture();
 }
 
 /*!
@@ -984,7 +984,7 @@ void QOpenGLWidget::setFormat(const QSurfaceFormat &format)
 {
     Q_UNUSED(format);
     Q_D(QOpenGLWidget);
-    if (d->initialized) {
+    if (Q_UNLIKELY(d->initialized)) {
         qWarning("QOpenGLWidget: Already initialized, setting the format has no effect");
         return;
     }

src/widgets/kernel/qshortcut.cpp

@@ -49,7 +49,7 @@
 QT_BEGIN_NAMESPACE
 
 #define QAPP_CHECK(functionName) \
-    if (!qApp) { \
+    if (Q_UNLIKELY(!qApp)) {                                            \
         qWarning("QShortcut: Initialize QApplication before calling '" functionName "'."); \
         return; \
     }
@@ -410,7 +410,7 @@ public:
 void QShortcutPrivate::redoGrab(QShortcutMap &map)
 {
     Q_Q(QShortcut);
-    if (!parent) {
+    if (Q_UNLIKELY(!parent)) {
         qWarning("QShortcut: No widget parent defined");
         return;
     }

src/widgets/kernel/qstackedlayout.cpp

@@ -57,7 +57,7 @@ QLayoutItem* QStackedLayoutPrivate::replaceAt(int idx, QLayoutItem *newitem)
     if (idx < 0 || idx >= list.size() || !newitem)
         return 0;
     QWidget *wdg = newitem->widget();
-    if (!wdg) {
+    if (Q_UNLIKELY(!wdg)) {
         qWarning("QStackedLayout::replaceAt: Only widgets can be added");
         return 0;
     }
@@ -367,7 +367,7 @@ int QStackedLayout::currentIndex() const
 void QStackedLayout::setCurrentWidget(QWidget *widget)
 {
     int index = indexOf(widget);
-    if (index == -1) {
+    if (Q_UNLIKELY(index == -1)) {
         qWarning("QStackedLayout::setCurrentWidget: Widget %p not contained in stack", widget);
         return;
     }
@@ -420,12 +420,12 @@ int QStackedLayout::count() const
 void QStackedLayout::addItem(QLayoutItem *item)
 {
     QWidget *widget = item->widget();
-    if (widget) {
+    if (Q_UNLIKELY(!widget)) {
+        qWarning("QStackedLayout::addItem: Only widgets can be added");
+        return;
+    }
     addWidget(widget);
     delete item;
-    } else {
-        qWarning("QStackedLayout::addItem: Only widgets can be added");
-    }
 }
 
 /*!

src/widgets/kernel/qtooltip.cpp

@@ -264,12 +264,12 @@ void QTipLabel::hideTipImmediately()
 
 void QTipLabel::setTipRect(QWidget *w, const QRect &r)
 {
-    if (!r.isNull() && !w)
+    if (Q_UNLIKELY(!r.isNull() && !w)) {
         qWarning("QToolTip::setTipRect: Cannot pass null widget if rect is set");
-    else{
+        return;
+    }
     widget = w;
     rect = r;
-    }
 }
 
 void QTipLabel::timerEvent(QTimerEvent *e)

src/widgets/kernel/qwidget.cpp

@@ -1528,7 +1528,7 @@ QWidget::~QWidget()
     d->data.in_destructor = true;
 
 #if defined (QT_CHECK_STATE)
-    if (paintingActive())
+    if (Q_UNLIKELY(paintingActive()))
         qWarning("QWidget: %s (%s) deleted while being painted", className(), name());
 #endif
 
@@ -3267,7 +3267,7 @@ void QWidget::addActions(QList<QAction*> actions)
 */
 void QWidget::insertAction(QAction *before, QAction *action)
 {
-    if(!action) {
+    if (Q_UNLIKELY(!action)) {
         qWarning("QWidget::insertAction: Attempt to insert null action");
         return;
     }
@@ -3913,7 +3913,7 @@ bool QWidgetPrivate::setMinimumSize_helper(int &minw, int &minh)
         mw = 0;
     if (mh == QWIDGETSIZE_MAX)
         mh = 0;
-    if (minw > QWIDGETSIZE_MAX || minh > QWIDGETSIZE_MAX) {
+    if (Q_UNLIKELY(minw > QWIDGETSIZE_MAX || minh > QWIDGETSIZE_MAX)) {
         qWarning("QWidget::setMinimumSize: (%s/%s) "
                 "The largest allowed size is (%d,%d)",
                  q->objectName().toLocal8Bit().data(), q->metaObject()->className(), QWIDGETSIZE_MAX,
@@ -3921,7 +3921,7 @@ bool QWidgetPrivate::setMinimumSize_helper(int &minw, int &minh)
         minw = mw = qMin<int>(minw, QWIDGETSIZE_MAX);
         minh = mh = qMin<int>(minh, QWIDGETSIZE_MAX);
     }
-    if (minw < 0 || minh < 0) {
+    if (Q_UNLIKELY(minw < 0 || minh < 0)) {
         qWarning("QWidget::setMinimumSize: (%s/%s) Negative sizes (%d,%d) "
                 "are not possible",
                 q->objectName().toLocal8Bit().data(), q->metaObject()->className(), minw, minh);
@@ -3995,7 +3995,7 @@ void QWidget::setMinimumSize(int minw, int minh)
 bool QWidgetPrivate::setMaximumSize_helper(int &maxw, int &maxh)
 {
     Q_Q(QWidget);
-    if (maxw > QWIDGETSIZE_MAX || maxh > QWIDGETSIZE_MAX) {
+    if (Q_UNLIKELY(maxw > QWIDGETSIZE_MAX || maxh > QWIDGETSIZE_MAX)) {
         qWarning("QWidget::setMaximumSize: (%s/%s) "
                 "The largest allowed size is (%d,%d)",
                  q->objectName().toLocal8Bit().data(), q->metaObject()->className(), QWIDGETSIZE_MAX,
@@ -4003,7 +4003,7 @@ bool QWidgetPrivate::setMaximumSize_helper(int &maxw, int &maxh)
         maxw = qMin<int>(maxw, QWIDGETSIZE_MAX);
         maxh = qMin<int>(maxh, QWIDGETSIZE_MAX);
     }
-    if (maxw < 0 || maxh < 0) {
+    if (Q_UNLIKELY(maxw < 0 || maxh < 0)) {
         qWarning("QWidget::setMaximumSize: (%s/%s) Negative sizes (%d,%d) "
                 "are not possible",
                 q->objectName().toLocal8Bit().data(), q->metaObject()->className(), maxw, maxh);
@@ -5104,12 +5104,12 @@ void QWidget::render(QPaintDevice *target, const QPoint &targetOffset,
 void QWidget::render(QPainter *painter, const QPoint &targetOffset,
                      const QRegion &sourceRegion, RenderFlags renderFlags)
 {
-    if (!painter) {
+    if (Q_UNLIKELY(!painter)) {
         qWarning("QWidget::render: Null pointer to painter");
         return;
     }
 
-    if (!painter->isActive()) {
+    if (Q_UNLIKELY(!painter->isActive())) {
         qWarning("QWidget::render: Cannot render with an inactive painter");
         return;
     }
@@ -5498,7 +5498,7 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
     if (!toBePainted.isEmpty()) {
         if (!onScreen || alsoOnScreen) {
             //update the "in paint event" flag
-            if (q->testAttribute(Qt::WA_WState_InPaintEvent))
+            if (Q_UNLIKELY(q->testAttribute(Qt::WA_WState_InPaintEvent)))
                 qWarning("QWidget::repaint: Recursive repaint detected");
             q->setAttribute(Qt::WA_WState_InPaintEvent);
 
@@ -5605,7 +5605,7 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
                 setSystemClip(pdev, QRegion());
             }
             q->setAttribute(Qt::WA_WState_InPaintEvent, false);
-            if (q->paintingActive())
+            if (Q_UNLIKELY(q->paintingActive()))
                 qWarning("QWidget::repaint: It is dangerous to leave painters active on a widget outside of the PaintEvent");
 
             if (paintEngine && paintEngine->autoDestruct()) {
@@ -5654,7 +5654,7 @@ void QWidgetPrivate::sendPaintEvent(const QRegion &toBePainted)
 void QWidgetPrivate::render(QPaintDevice *target, const QPoint &targetOffset,
                             const QRegion &sourceRegion, QWidget::RenderFlags renderFlags)
 {
-    if (!target) {
+    if (Q_UNLIKELY(!target)) {
         qWarning("QWidget::render: null pointer to paint device");
         return;
     }
@@ -5788,7 +5788,7 @@ QRectF QWidgetEffectSourcePrivate::boundingRect(Qt::CoordinateSystem system) con
     if (system != Qt::DeviceCoordinates)
         return m_widget->rect();
 
-    if (!context) {
+    if (Q_UNLIKELY(!context)) {
         // Device coordinates without context not yet supported.
         qWarning("QGraphicsEffectSource::boundingRect: Not yet implemented, lacking device context");
         return QRectF();
@@ -5820,7 +5820,7 @@ QPixmap QWidgetEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QPoint *
                                            QGraphicsEffect::PixmapPadMode mode) const
 {
     const bool deviceCoordinates = (system == Qt::DeviceCoordinates);
-    if (!context && deviceCoordinates) {
+    if (Q_UNLIKELY(!context && deviceCoordinates)) {
         // Device coordinates without context not yet supported.
         qWarning("QGraphicsEffectSource::pixmap: Not yet implemented, lacking device context");
         return QPixmap();
@@ -6353,7 +6353,7 @@ void QWidget::setFocusProxy(QWidget * w)
         return;
 
     for (QWidget* fp  = w; fp; fp = fp->focusProxy()) {
-        if (fp == this) {
+        if (Q_UNLIKELY(fp == this)) {
             qWarning("QWidget: %s (%s) already in focus proxy chain", metaObject()->className(), objectName().toLocal8Bit().constData());
             return;
         }
@@ -6867,7 +6867,7 @@ void QWidget::setTabOrder(QWidget* first, QWidget *second)
     if (!first || !second || first->focusPolicy() == Qt::NoFocus || second->focusPolicy() == Qt::NoFocus)
         return;
 
-    if (first->window() != second->window()) {
+    if (Q_UNLIKELY(first->window() != second->window())) {
         qWarning("QWidget::setTabOrder: 'first' and 'second' must be in the same window");
         return;
     }
@@ -10024,12 +10024,12 @@ QLayout *QWidget::layout() const
 
 void QWidget::setLayout(QLayout *l)
 {
-    if (!l) {
+    if (Q_UNLIKELY(!l)) {
         qWarning("QWidget::setLayout: Cannot set layout to 0");
         return;
     }
     if (layout()) {
-        if (layout() != l)
+        if (Q_UNLIKELY(layout() != l))
             qWarning("QWidget::setLayout: Attempting to set QLayout \"%s\" on %s \"%s\", which already has a"
                      " layout", l->objectName().toLocal8Bit().data(), metaObject()->className(),
                      objectName().toLocal8Bit().data());
@@ -11374,7 +11374,7 @@ void QWidgetPrivate::setWindowModified_helper()
         return;
     bool on = q->testAttribute(Qt::WA_WindowModified);
     if (!platformWindow->setWindowModified(on)) {
-        if (!q->windowTitle().contains(QLatin1String("[*]")) && on)
+        if (Q_UNLIKELY(on && !q->windowTitle().contains(QLatin1String("[*]"))))
             qWarning("QWidget::setWindowModified: The window title does not contain a '[*]' placeholder");
         setWindowTitle_helper(q->windowTitle());
         setWindowIconText_helper(q->windowIconText());
@@ -12124,7 +12124,7 @@ QOpenGLContext *QWidgetPrivate::shareContext() const
 #ifdef QT_NO_OPENGL
     return 0;
 #else
-    if (!extra || !extra->topextra || !extra->topextra->window) {
+    if (Q_UNLIKELY(!extra || !extra->topextra || !extra->topextra->window)) {
         qWarning("Asking for share context for widget that does not have a window handle");
         return 0;
     }

src/widgets/kernel/qwidgetbackingstore.cpp

@@ -1554,7 +1554,7 @@ void QWidgetPrivate::repaint_sys(const QRegion &rgn)
         QWidgetBackingStore::unflushPaint(q, toBePainted);
 #endif
 
-    if (q->paintingActive())
+    if (Q_UNLIKELY(q->paintingActive()))
         qWarning("QWidget::repaint: It is dangerous to leave painters active on a widget outside of the PaintEvent");
 }
 

src/widgets/kernel/qwidgetwindow.cpp

@@ -798,7 +798,7 @@ void QWidgetWindow::handleDragLeaveEvent(QDragLeaveEvent *event)
 
 void QWidgetWindow::handleDropEvent(QDropEvent *event)
 {
-    if (m_dragTarget.isNull()) {
+    if (Q_UNLIKELY(m_dragTarget.isNull())) {
         qWarning() << Q_FUNC_INFO << m_widget << ": No drag target set.";
         event->ignore();
         return;

src/widgets/kernel/qwindowcontainer.cpp

@@ -193,7 +193,7 @@ QWindowContainer::QWindowContainer(QWindow *embeddedWindow, QWidget *parent, Qt:
     : QWidget(*new QWindowContainerPrivate, parent, flags)
 {
     Q_D(QWindowContainer);
-    if (!embeddedWindow) {
+    if (Q_UNLIKELY(!embeddedWindow)) {
         qWarning("QWindowContainer: embedded window cannot be null");
         return;
     }

src/widgets/styles/qandroidstyle.cpp

@@ -84,7 +84,7 @@ QAndroidStyle::QAndroidStyle()
          ++objectIterator) {
         QString key = objectIterator.key();
         QJsonValue value = objectIterator.value();
-        if (!value.isObject()) {
+        if (Q_UNLIKELY(!value.isObject())) {
             qWarning("Style.json structure is unrecognized.");
             continue;
         }

src/widgets/styles/qdrawutil.cpp

@@ -87,7 +87,7 @@ void qDrawShadeLine(QPainter *p, int x1, int y1, int x2, int y2,
                      const QPalette &pal, bool sunken,
                      int lineWidth, int midLineWidth)
 {
-    if (!(p && lineWidth >= 0 && midLineWidth >= 0))        {
+    if (Q_UNLIKELY(!p || lineWidth < 0 || midLineWidth < 0)) {
         qWarning("qDrawShadeLine: Invalid parameters");
         return;
     }
@@ -203,7 +203,7 @@ void qDrawShadeRect(QPainter *p, int x, int y, int w, int h,
 {
     if (w == 0 || h == 0)
         return;
-    if (! (w > 0 && h > 0 && lineWidth >= 0 && midLineWidth >= 0)) {
+    if (Q_UNLIKELY(w < 0 || h < 0 || lineWidth < 0 || midLineWidth < 0)) {
         qWarning("qDrawShadeRect: Invalid parameters");
         return;
     }
@@ -303,7 +303,7 @@ void qDrawShadePanel(QPainter *p, int x, int y, int w, int h,
 {
     if (w == 0 || h == 0)
         return;
-    if (!(w > 0 && h > 0 && lineWidth >= 0)) {
+    if (Q_UNLIKELY(w < 0 || h < 0 || lineWidth < 0)) {
         qWarning("qDrawShadePanel: Invalid parameters");
     }
     QColor shade = pal.dark().color();
@@ -509,7 +509,7 @@ void qDrawPlainRect(QPainter *p, int x, int y, int w, int h, const QColor &c,
 {
     if (w == 0 || h == 0)
         return;
-    if (!(w > 0 && h > 0 && lineWidth >= 0)) {
+    if (Q_UNLIKELY(w < 0 || h < 0 || lineWidth < 0)) {
         qWarning("qDrawPlainRect: Invalid parameters");
     }
     QPen   oldPen   = p->pen();

src/widgets/styles/qstylesheetstyle.cpp

@@ -1547,7 +1547,7 @@ QVector<QCss::StyleRule> QStyleSheetStyle::styleRules(const QObject *obj) const
             if (ss.startsWith(QLatin1String("file:///")))
                 ss.remove(0, 8);
             parser.init(ss, qApp->styleSheet() != ss);
-            if (!parser.parse(&appSs))
+            if (Q_UNLIKELY(!parser.parse(&appSs)))
                 qWarning("Could not parse application stylesheet");
             appSs.origin = StyleSheetOrigin_Inline;
             appSs.depth = 1;
@@ -1569,7 +1569,7 @@ QVector<QCss::StyleRule> QStyleSheetStyle::styleRules(const QObject *obj) const
             parser.init(styleSheet);
             if (!parser.parse(&ss)) {
                 parser.init(QLatin1String("* {") + styleSheet + QLatin1Char('}'));
-                if (!parser.parse(&ss))
+                if (Q_UNLIKELY(!parser.parse(&ss)))
                    qWarning("Could not parse stylesheet of object %p", o);
             }
             ss.origin = StyleSheetOrigin_Inline;
@@ -2515,12 +2515,12 @@ void QStyleSheetStyle::setProperties(QWidget *w)
 
         const QMetaObject *metaObject = w->metaObject();
         int index = metaObject->indexOfProperty(property.toLatin1());
-        if (index == -1) {
+        if (Q_UNLIKELY(index == -1)) {
             qWarning() << w << " does not have a property named " << property;
             continue;
         }
         const QMetaProperty metaProperty = metaObject->property(index);
-        if (!metaProperty.isWritable() || !metaProperty.isDesignable()) {
+        if (Q_UNLIKELY(!metaProperty.isWritable() || !metaProperty.isDesignable())) {
             qWarning() << w << " cannot design property named " << property;
             continue;
         }

src/widgets/styles/qwindowsvistastyle.cpp

@@ -2471,12 +2471,12 @@ bool QWindowsVistaStylePrivate::initTreeViewTheming()
         return true;
 
     m_treeViewHelper = createTreeViewHelperWindow();
-    if (!m_treeViewHelper) {
+    if (Q_UNLIKELY(!m_treeViewHelper)) {
         qWarning("%s: Unable to create the treeview helper window.", Q_FUNC_INFO);
         return false;
     }
     const HRESULT hr = QWindowsXPStylePrivate::pSetWindowTheme(m_treeViewHelper, L"explorer", NULL);
-    if (hr != S_OK) {
+    if (Q_UNLIKELY(hr != S_OK)) {
         qErrnoWarning("%s: SetWindowTheme() failed.", Q_FUNC_INFO);
         return false;
     }

src/widgets/styles/qwindowsxpstyle.cpp

@@ -337,14 +337,14 @@ void QWindowsXPStylePrivate::cleanupHandleMap()
 
 HTHEME QWindowsXPStylePrivate::createTheme(int theme, HWND hwnd)
 {
-    if (theme < 0 || theme >= NThemes || !hwnd) {
+    if (Q_UNLIKELY(theme < 0 || theme >= NThemes || !hwnd)) {
         qWarning("%s: Invalid parameters #%d, %p", Q_FUNC_INFO, theme, hwnd);
         return 0;
     }
     if (!m_themes[theme]) {
         const wchar_t *name = themeNames[theme];
         m_themes[theme] = pOpenThemeData(hwnd, name);
-        if (!m_themes[theme])
+        if (Q_UNLIKELY(!m_themes[theme]))
             qErrnoWarning("%s: OpenThemeData() failed for theme %d (%s).",
                           Q_FUNC_INFO, theme, qPrintable(themeName(theme)));
     }
@@ -504,13 +504,13 @@ HBITMAP QWindowsXPStylePrivate::buffer(int w, int h)
     GdiFlush();
     nullBitmap = (HBITMAP)SelectObject(bufferDC, bufferBitmap);
 
-    if (!bufferBitmap) {
+    if (Q_UNLIKELY(!bufferBitmap)) {
         qErrnoWarning("QWindowsXPStylePrivate::buffer(%dx%d), CreateDIBSection() failed.", w, h);
         bufferW = 0;
         bufferH = 0;
         return 0;
     }
-    if (!bufferPixels) {
+    if (Q_UNLIKELY(!bufferPixels)) {
         qErrnoWarning("QWindowsXPStylePrivate::buffer(%dx%d), CreateDIBSection() did not allocate pixel data.", w, h);
         bufferW = 0;
         bufferH = 0;