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>

1 files changed, 19 insertions, 19 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 0f580f7369..e8169d0bd1 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/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;
     }