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, 19 insertions, 19 deletions

diff --git a/src/widgets/dialogs/qwizard.cpp b/src/widgets/dialogs/qwizard.cpp
index 996e5819ff..c050b5b097 100644
--- a/src/widgets/dialogs/qwizard.cpp
+++ b/src/widgets/dialogs/qwizard.cpp
@@ -799,7 +799,7 @@ void QWizardPrivate::addField(const QWizardField &field)
     QWizardField myField = field;
     myField.resolve(defaultPropertyTable);
 
-    if (fieldIndexMap.contains(myField.name)) {
+    if (Q_UNLIKELY(fieldIndexMap.contains(myField.name))) {
         qWarning("QWizardPage::addField: Duplicate field '%ls'", qUtf16Printable(myField.name));
         return;
     }
@@ -2256,17 +2256,17 @@ void QWizard::setPage(int theid, QWizardPage *page)
 {
     Q_D(QWizard);
 
-    if (!page) {
+    if (Q_UNLIKELY(!page)) {
         qWarning("QWizard::setPage: Cannot insert null page");
         return;
     }
 
-    if (theid == -1) {
+    if (Q_UNLIKELY(theid == -1)) {
         qWarning("QWizard::setPage: Cannot insert page with ID -1");
         return;
     }
 
-    if (d->pageMap.contains(theid)) {
+    if (Q_UNLIKELY(d->pageMap.contains(theid))) {
         qWarning("QWizard::setPage: Page with duplicate ID %d ignored", theid);
         return;
     }
@@ -2450,7 +2450,7 @@ void QWizard::setStartId(int theid)
         return;
     }
 
-    if (!d->pageMap.contains(newStart)) {
+    if (Q_UNLIKELY(!d->pageMap.contains(newStart))) {
         qWarning("QWizard::setStartId: Invalid page ID %d", newStart);
         return;
     }
@@ -2508,15 +2508,15 @@ void QWizard::setField(const QString &name, const QVariant &value)
     Q_D(QWizard);
 
     int index = d->fieldIndexMap.value(name, -1);
-    if (index != -1) {
-        const QWizardField &field = d->fields.at(index);
-        if (!field.object->setProperty(field.property, value))
-            qWarning("QWizard::setField: Couldn't write to property '%s'",
-                     field.property.constData());
+    if (Q_UNLIKELY(index == -1)) {
+        qWarning("QWizard::setField: No such field '%ls'", qUtf16Printable(name));
         return;
     }
 
-    qWarning("QWizard::setField: No such field '%ls'", qUtf16Printable(name));
+    const QWizardField &field = d->fields.at(index);
+    if (Q_UNLIKELY(!field.object->setProperty(field.property, value)))
+        qWarning("QWizard::setField: Couldn't write to property '%s'",
+                 field.property.constData());
 }
 
 /*!
@@ -2531,13 +2531,13 @@ QVariant QWizard::field(const QString &name) const
     Q_D(const QWizard);
 
     int index = d->fieldIndexMap.value(name, -1);
-    if (index != -1) {
-        const QWizardField &field = d->fields.at(index);
-        return field.object->property(field.property);
+    if (Q_UNLIKELY(index == -1)) {
+        qWarning("QWizard::field: No such field '%ls'", qUtf16Printable(name));
+        return QVariant();
     }
 
-    qWarning("QWizard::field: No such field '%ls'", qUtf16Printable(name));
-    return QVariant();
+    const QWizardField &field = d->fields.at(index);
+    return field.object->property(field.property);
 }
 
 /*!
@@ -2763,7 +2763,7 @@ void QWizard::setButtonLayout(const QList<WizardButton> &layout)
         // O(n^2), but n is very small
         for (int j = 0; j < i; ++j) {
             WizardButton button2 = layout.at(j);
-            if (button2 == button1) {
+            if (Q_UNLIKELY(button2 == button1)) {
                 qWarning("QWizard::setButtonLayout: Duplicate button in layout");
                 return;
             }
@@ -3140,11 +3140,11 @@ void QWizard::next()
     if (validateCurrentPage()) {
         int next = nextId();
         if (next != -1) {
-            if (d->history.contains(next)) {
+            if (Q_UNLIKELY(d->history.contains(next))) {
                 qWarning("QWizard::next: Page %d already met", next);
                 return;
             }
-            if (!d->pageMap.contains(next)) {
+            if (Q_UNLIKELY(!d->pageMap.contains(next))) {
                 qWarning("QWizard::next: No such page %d", next);
                 return;
             }