QtWidgets: use Q_UNLIKELY for every qWarning() (1)

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 util/,
dialogs/ and widgets/ 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 QSystemTrayIcon::setVisible(), 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.

Change-Id: I3564c5a5deacba49d67d3989fb0b53e680c57fcb
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/widgets/widgets/qsplitter.cpp b/src/widgets/widgets/qsplitter.cpp
index c2081c15f8..9162ba3c12 100644
--- a/src/widgets/widgets/qsplitter.cpp
+++ b/src/widgets/widgets/qsplitter.cpp
@@ -1058,7 +1058,7 @@ void QSplitter::setCollapsible(int index, bool collapse)
 {
     Q_D(QSplitter);
 
-    if (index < 0 || index >= d->list.size()) {
+    if (Q_UNLIKELY(index < 0 || index >= d->list.size())) {
         qWarning("QSplitter::setCollapsible: Index %d out of range", index);
         return;
     }
@@ -1071,7 +1071,7 @@ void QSplitter::setCollapsible(int index, bool collapse)
 bool QSplitter::isCollapsible(int index) const
 {
     Q_D(const QSplitter);
-    if (index < 0 || index >= d->list.size()) {
+    if (Q_UNLIKELY(index < 0 || index >= d->list.size())) {
         qWarning("QSplitter::isCollapsible: Index %d out of range", index);
         return false;
     }
@@ -1215,7 +1215,7 @@ void QSplitter::childEvent(QChildEvent *c)
 {
     Q_D(QSplitter);
     if (!c->child()->isWidgetType()) {
-        if (c->type() == QEvent::ChildAdded && qobject_cast<QLayout *>(c->child()))
+        if (Q_UNLIKELY(c->type() == QEvent::ChildAdded && qobject_cast<QLayout *>(c->child())))
             qWarning("Adding a QLayout to a QSplitter is not supported.");
         return;
     }