Use Q_UNLIKELY for every qFatal()/qCritical()

If, after checking a condition, we issue a qFatal()
or a qCritical(), 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.

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 some cases, simplified the expressions newly wrapped
in Q_UNLIKELY as a drive-by.

Change-Id: I67537d62b04bc6977d69254690c5ebbdf98bfd6d
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 9 insertions, 9 deletions

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 248a7d0d1d..f88f6dc01a 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -1065,9 +1065,7 @@ static void init_platform(const QString &pluginArgument, const QString &platform
 
    // Create the platform integration.
     QGuiApplicationPrivate::platform_integration = QPlatformIntegrationFactory::create(name, arguments, argc, argv, platformPluginPath);
-    if (QGuiApplicationPrivate::platform_integration) {
-        QGuiApplicationPrivate::platform_name = new QString(name);
-    } else {
+    if (Q_UNLIKELY(!QGuiApplicationPrivate::platform_integration)) {
         QStringList keys = QPlatformIntegrationFactory::keys(platformPluginPath);
 
         QString fatalMessage
@@ -1087,6 +1085,8 @@ static void init_platform(const QString &pluginArgument, const QString &platform
         return;
     }
 
+    QGuiApplicationPrivate::platform_name = new QString(name);
+
     // Many platforms have created QScreens at this point. Finish initializing
     // QHighDpiScaling to be prepared for early calls to qt_defaultDpi().
     if (QGuiApplication::primaryScreen()) {
@@ -1414,16 +1414,16 @@ void QGuiApplicationPrivate::init()
 
     if (loadTestability) {
         QLibrary testLib(QStringLiteral("qttestability"));
-        if (testLib.load()) {
+        if (Q_UNLIKELY(!testLib.load())) {
+            qCritical() << "Library qttestability load failed:" << testLib.errorString();
+        } else {
             typedef void (*TasInitialize)(void);
             TasInitialize initFunction = (TasInitialize)testLib.resolve("qt_testability_init");
-            if (initFunction) {
-                initFunction();
-            } else {
+            if (Q_UNLIKELY(!initFunction)) {
                 qCritical() << "Library qttestability resolve failed!";
+            } else {
+                initFunction();
             }
-        } else {
-            qCritical() << "Library qttestability load failed:" << testLib.errorString();
         }
     }
 #else