diff --git a/src/corelib/io/qprocess_unix.cpp b/src/corelib/io/qprocess_unix.cpp
index 472d8699a2..9a25f56c5f 100644
--- a/src/corelib/io/qprocess_unix.cpp
+++ b/src/corelib/io/qprocess_unix.cpp
@@ -560,7 +560,7 @@ static int doSpawn(pid_t *ppid, const posix_spawn_file_actions_t *file_actions,
             qWarning("ThreadCtl(): failed to chdir to %s", oldWorkingDir);
 
 #  ifdef Q_OS_QNX
-        if (ThreadCtl(_NTO_TCTL_THREADS_CONT, 0) == -1)
+        if (Q_UNLIKELY(ThreadCtl(_NTO_TCTL_THREADS_CONT, 0) == -1))
             qFatal("ThreadCtl(): cannot resume threads: %s", qPrintable(qt_error_string(errno)));
 #  endif
     }
diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 5fe0ea3559..8d9b923e61 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -417,7 +417,7 @@ QCoreApplicationPrivate::QCoreApplicationPrivate(int &aargc, char **aargv, uint
     QCoreApplicationPrivate::is_app_closing = false;
 
 #  if defined(Q_OS_UNIX)
-    if (!setuidAllowed && (geteuid() != getuid()))
+    if (Q_UNLIKELY(!setuidAllowed && (geteuid() != getuid())))
         qFatal("FATAL: The application binary appears to be running setuid, this is a security hole.");
 #  endif // Q_OS_UNIX
 
diff --git a/src/corelib/kernel/qeventdispatcher_unix.cpp b/src/corelib/kernel/qeventdispatcher_unix.cpp
index 30122e809b..d45ea30a45 100644
--- a/src/corelib/kernel/qeventdispatcher_unix.cpp
+++ b/src/corelib/kernel/qeventdispatcher_unix.cpp
@@ -135,7 +135,7 @@ QEventDispatcherUNIXPrivate::QEventDispatcherUNIXPrivate()
     }
 #endif
 
-    if (pipefail)
+    if (Q_UNLIKELY(pipefail))
         qFatal("QEventDispatcherUNIXPrivate(): Can not continue without a thread pipe");
 
     sn_highest = -1;
diff --git a/src/corelib/kernel/qeventdispatcher_win.cpp b/src/corelib/kernel/qeventdispatcher_win.cpp
index ecaa78cbbc..47b869f62a 100644
--- a/src/corelib/kernel/qeventdispatcher_win.cpp
+++ b/src/corelib/kernel/qeventdispatcher_win.cpp
@@ -667,7 +667,7 @@ void QEventDispatcherWin32::installMessageHook()
 #ifndef Q_OS_WINCE
     // setup GetMessage hook needed to drive our posted events
     d->getMessageHook = SetWindowsHookEx(WH_GETMESSAGE, (HOOKPROC) qt_GetMessageHook, NULL, GetCurrentThreadId());
-    if (!d->getMessageHook) {
+    if (Q_UNLIKELY(!d->getMessageHook)) {
         int errorCode = GetLastError();
         qFatal("Qt: INTERNAL ERROR: failed to install GetMessage hook: %d, %s",
                errorCode, qPrintable(qt_error_string(errorCode)));
diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index e6d745bb74..c0caa3cca5 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -1074,7 +1074,7 @@ int QMetaType::registerNormalizedType(const NS(QByteArray) &normalizedTypeName,
         previousFlags = QMetaType::typeFlags(idx);
     }
 
-    if (previousSize != size) {
+    if (Q_UNLIKELY(previousSize != size)) {
         qFatal("QMetaType::registerType: Binary compatibility break "
             "-- Size mismatch for type '%s' [%i]. Previously registered "
             "size %i, now registering size %i.",
@@ -1084,7 +1084,7 @@ int QMetaType::registerNormalizedType(const NS(QByteArray) &normalizedTypeName,
     // these flags cannot change in a binary compatible way:
     const int binaryCompatibilityFlag = PointerToQObject | IsEnumeration | SharedPointerToQObject
                                                 | WeakPointerToQObject | TrackingPointerToQObject;
-    if ((previousFlags ^ flags) & binaryCompatibilityFlag) {
+    if (Q_UNLIKELY((previousFlags ^ flags) & binaryCompatibilityFlag)) {
 
         const char *msg = "QMetaType::registerType: Binary compatibility break. "
                 "\nType flags for type '%s' [%i] don't match. Previously "
diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index c9884cd76c..4717cfbf3c 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -203,7 +203,7 @@ QObjectPrivate::QObjectPrivate(int version)
     // This allows incompatible versions to be loaded, possibly for testing.
     Q_UNUSED(version);
 #else
-    if (version != QObjectPrivateVersion)
+    if (Q_UNLIKELY(version != QObjectPrivateVersion))
         qFatal("Cannot mix incompatible Qt library (version 0x%x) with this library (version 0x%x)",
                 version, QObjectPrivateVersion);
 #endif
diff --git a/src/corelib/tools/qhash.cpp b/src/corelib/tools/qhash.cpp
index b334a697a9..7724516a5d 100644
--- a/src/corelib/tools/qhash.cpp
+++ b/src/corelib/tools/qhash.cpp
@@ -682,17 +682,17 @@ void QHashData::dump()
 
 void QHashData::checkSanity()
 {
-    if (fakeNext)
+    if (Q_UNLIKELY(fakeNext))
         qFatal("Fake next isn't 0");
 
     for (int i = 0; i < numBuckets; ++i) {
         Node *n = buckets[i];
         Node *p = n;
-        if (!n)
+        if (Q_UNLIKELY(!n))
             qFatal("%d: Bucket entry is 0", i);
         if (n != reinterpret_cast<Node *>(this)) {
             while (n != reinterpret_cast<Node *>(this)) {
-                if (!n->next)
+                if (Q_UNLIKELY(!n->next))
                     qFatal("%d: Next of %p is 0, should be %p", i, n, this);
                 n = n->next;
             }
diff --git a/src/corelib/tools/qsharedpointer.cpp b/src/corelib/tools/qsharedpointer.cpp
index 4d30396cb6..b5e27cc720 100644
--- a/src/corelib/tools/qsharedpointer.cpp
+++ b/src/corelib/tools/qsharedpointer.cpp
@@ -1508,7 +1508,7 @@ void QtSharedPointer::internalSafetyCheckAdd(const void *d_ptr, const volatile v
     //qDebug("Adding d=%p value=%p", d_ptr, ptr);
 
     const void *other_d_ptr = kp->dataPointers.value(ptr, 0);
-    if (other_d_ptr) {
+    if (Q_UNLIKELY(other_d_ptr)) {
 #  ifdef BACKTRACE_SUPPORTED
         printBacktrace(knownPointers()->dPointers.value(other_d_ptr).backtrace);
 #  endif
@@ -1539,7 +1539,7 @@ void QtSharedPointer::internalSafetyCheckRemove(const void *d_ptr)
     QMutexLocker lock(&kp->mutex);
 
     QHash<const void *, Data>::iterator it = kp->dPointers.find(d_ptr);
-    if (it == kp->dPointers.end()) {
+    if (Q_UNLIKELY(it == kp->dPointers.end())) {
         qFatal("QSharedPointer: internal self-check inconsistency: pointer %p was not tracked. "
                "To use QT_SHAREDPOINTER_TRACK_POINTERS, you have to enable it throughout "
                "in your code.", d_ptr);
@@ -1566,10 +1566,10 @@ void QtSharedPointer::internalSafetyCheckCleanCheck()
     KnownPointers *const kp = knownPointers();
     Q_ASSERT_X(kp, "internalSafetyCheckSelfCheck()", "Called after global statics deletion!");
 
-    if (kp->dPointers.size() != kp->dataPointers.size())
+    if (Q_UNLIKELY(kp->dPointers.size() != kp->dataPointers.size()))
         qFatal("Internal consistency error: the number of pointers is not equal!");
 
-    if (!kp->dPointers.isEmpty())
+    if (Q_UNLIKELY(!kp->dPointers.isEmpty()))
         qFatal("Pointer cleaning failed: %d entries remaining", kp->dPointers.size());
 #  endif
 }
diff --git a/src/corelib/tools/qsimd.cpp b/src/corelib/tools/qsimd.cpp
index 3e4fdfaaf1..0b3b84a302 100644
--- a/src/corelib/tools/qsimd.cpp
+++ b/src/corelib/tools/qsimd.cpp
@@ -685,7 +685,7 @@ void qDetectCpuFeatures()
 #else
     bool runningOnValgrind = false;
 #endif
-    if (!runningOnValgrind && (minFeature != 0 && (f & minFeature) != minFeature)) {
+    if (Q_UNLIKELY(!runningOnValgrind && minFeature != 0 && (f & minFeature) != minFeature)) {
         quint64 missing = minFeature & ~f;
         fprintf(stderr, "Incompatible processor. This Qt build requires the following features:\n   ");
         for (int i = 0; i < features_count; ++i) {
diff --git a/src/dbus/qdbus_symbols.cpp b/src/dbus/qdbus_symbols.cpp
index 395a436869..3f5df41582 100644
--- a/src/dbus/qdbus_symbols.cpp
+++ b/src/dbus/qdbus_symbols.cpp
@@ -130,11 +130,11 @@ void (*qdbus_resolve_conditionally(const char *name))()
 void (*qdbus_resolve_me(const char *name))()
 {
 #ifndef QT_NO_LIBRARY
-    if (!qdbus_loadLibDBus())
+    if (Q_UNLIKELY(!qdbus_loadLibDBus()))
         qFatal("Cannot find libdbus-1 in your system to resolve symbol '%s'.", name);
 
     QFunctionPointer ptr = qdbus_libdbus->resolve(name);
-    if (!ptr)
+    if (Q_UNLIKELY(!ptr))
         qFatal("Cannot resolve '%s' in your libdbus-1.", name);
 
     return ptr;
diff --git a/src/dbus/qdbusintegrator.cpp b/src/dbus/qdbusintegrator.cpp
index d3f899676b..1aac16119b 100644
--- a/src/dbus/qdbusintegrator.cpp
+++ b/src/dbus/qdbusintegrator.cpp
@@ -868,7 +868,7 @@ void QDBusConnectionPrivate::deliverCall(QObject *object, int /*flags*/, const Q
                 *reinterpret_cast<const QDBusArgument *>(arg.constData());
             QVariant &out = auxParameters[auxParameters.count() - 1];
 
-            if (!QDBusMetaType::demarshall(in, out.userType(), out.data()))
+            if (Q_UNLIKELY(!QDBusMetaType::demarshall(in, out.userType(), out.data())))
                 qFatal("Internal error: demarshalling function for type '%s' (%d) failed!",
                        out.typeName(), out.userType());
 
diff --git a/src/dbus/qdbuspendingcall.cpp b/src/dbus/qdbuspendingcall.cpp
index c93d6acf84..c20b56f973 100644
--- a/src/dbus/qdbuspendingcall.cpp
+++ b/src/dbus/qdbuspendingcall.cpp
@@ -190,7 +190,7 @@ void QDBusPendingCallPrivate::setMetaTypes(int count, const int *types)
     sig.reserve(count + count / 2);
     for (int i = 0; i < count; ++i) {
         const char *typeSig = QDBusMetaType::typeToSignature(types[i]);
-        if (!typeSig) {
+        if (Q_UNLIKELY(!typeSig)) {
             qFatal("QDBusPendingReply: type %s is not registered with QtDBus",
                    QMetaType::typeName(types[i]));
         }
diff --git a/src/gui/image/qpixmap.cpp b/src/gui/image/qpixmap.cpp
index e53af8038f..492268402d 100644
--- a/src/gui/image/qpixmap.cpp
+++ b/src/gui/image/qpixmap.cpp
@@ -64,7 +64,7 @@ QT_BEGIN_NAMESPACE
 
 static bool qt_pixmap_thread_test()
 {
-    if (!QCoreApplication::instance()) {
+    if (Q_UNLIKELY(!QCoreApplication::instance())) {
         qFatal("QPixmap: Must construct a QGuiApplication before a QPixmap");
         return false;
     }
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
diff --git a/src/gui/kernel/qopenglcontext.cpp b/src/gui/kernel/qopenglcontext.cpp
index 85d05959de..3a51c2b7b2 100644
--- a/src/gui/kernel/qopenglcontext.cpp
+++ b/src/gui/kernel/qopenglcontext.cpp
@@ -948,7 +948,7 @@ bool QOpenGLContext::makeCurrent(QSurface *surface)
     if (!isValid())
         return false;
 
-    if (thread() != QThread::currentThread())
+    if (Q_UNLIKELY(thread() != QThread::currentThread()))
         qFatal("Cannot make QOpenGLContext current in a different thread");
 
     if (!surface) {
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 2b9340c04d..95f0f1cc90 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -212,7 +212,7 @@ void QWindowPrivate::init()
 
     // If your application aborts here, you are probably creating a QWindow
     // before the screen list is populated.
-    if (!parentWindow && !topLevelScreen) {
+    if (Q_UNLIKELY(!parentWindow && !topLevelScreen)) {
         qFatal("Cannot create window: no screens available");
         exit(1);
     }
diff --git a/src/gui/opengl/qopenglengineshadermanager.cpp b/src/gui/opengl/qopenglengineshadermanager.cpp
index 40f4ce94c2..7bdd3cb1bb 100644
--- a/src/gui/opengl/qopenglengineshadermanager.cpp
+++ b/src/gui/opengl/qopenglengineshadermanager.cpp
@@ -191,7 +191,7 @@ QOpenGLEngineSharedShaders::QOpenGLEngineSharedShaders(QOpenGLContext* context)
 #if defined(QT_DEBUG)
         // Check that all the elements have been filled:
         for (int i = 0; i < TotalSnippetCount; ++i) {
-            if (qShaderSnippets[i] == 0) {
+            if (Q_UNLIKELY(!qShaderSnippets[i])) {
                 qFatal("Shader snippet for %s (#%d) is missing!",
                        snippetNameStr(SnippetName(i)).constData(), i);
             }
@@ -240,11 +240,11 @@ QOpenGLEngineSharedShaders::QOpenGLEngineSharedShaders(QOpenGLContext* context)
 
     simpleShaderProg->link();
 
-    if (simpleShaderProg->isLinked()) {
+    if (Q_UNLIKELY(!simpleShaderProg->isLinked())) {
+        qCritical("Errors linking simple shader: %s", qPrintable(simpleShaderProg->log()));
+    } else {
         if (!inCache)
             simpleShaderCache.store(simpleShaderProg, context);
-    } else {
-        qCritical("Errors linking simple shader: %s", qPrintable(simpleShaderProg->log()));
     }
 
     // Compile the blit shader:
@@ -281,11 +281,11 @@ QOpenGLEngineSharedShaders::QOpenGLEngineSharedShaders(QOpenGLContext* context)
     }
 
     blitShaderProg->link();
-    if (blitShaderProg->isLinked()) {
+    if (Q_UNLIKELY(!blitShaderProg->isLinked())) {
+        qCritical("Errors linking blit shader: %s", qPrintable(blitShaderProg->log()));
+    } else {
         if (!inCache)
             blitShaderCache.store(blitShaderProg, context);
-    } else {
-        qCritical("Errors linking blit shader: %s", qPrintable(blitShaderProg->log()));
     }
 
 #ifdef QT_GL_SHARED_SHADER_DEBUG
diff --git a/src/gui/opengl/qopenglfunctions.cpp b/src/gui/opengl/qopenglfunctions.cpp
index d614ad8401..bfd30735b2 100644
--- a/src/gui/opengl/qopenglfunctions.cpp
+++ b/src/gui/opengl/qopenglfunctions.cpp
@@ -5795,7 +5795,9 @@ QOpenGLES3Helper::QOpenGLES3Helper()
 {
     m_supportedVersion = qMakePair(2, 0);
 
-    if (init()) {
+    if (Q_UNLIKELY(!init())) {
+        qFatal("Failed to load libGLESv2");
+    } else {
         const QPair<int, int> contextVersion = QOpenGLContext::currentContext()->format().version();
 
         qCDebug(lcGLES3, "Resolving OpenGL ES 3.0 entry points");
@@ -5993,8 +5995,6 @@ QOpenGLES3Helper::QOpenGLES3Helper()
             }
             m_supportedVersion = qMakePair(3, 1);
         }
-    } else {
-        qFatal("Failed to load libGLESv2");
     }
 }
 
diff --git a/src/gui/text/qfontdatabase.cpp b/src/gui/text/qfontdatabase.cpp
index 80908122a8..8916705c0e 100644
--- a/src/gui/text/qfontdatabase.cpp
+++ b/src/gui/text/qfontdatabase.cpp
@@ -1339,7 +1339,7 @@ QString QFontDatabase::styleString(const QFontInfo &fontInfo)
 */
 QFontDatabase::QFontDatabase()
 {
-    if (!qApp || !QGuiApplicationPrivate::platformIntegration())
+    if (Q_UNLIKELY(!qApp || !QGuiApplicationPrivate::platformIntegration()))
         qFatal("QFontDatabase: Must construct a QGuiApplication before accessing QFontDatabase");
 
     QMutexLocker locker(fontDatabaseMutex());
diff --git a/src/network/access/qhttpnetworkconnection.cpp b/src/network/access/qhttpnetworkconnection.cpp
index c4cb8e65c0..bb1580044f 100644
--- a/src/network/access/qhttpnetworkconnection.cpp
+++ b/src/network/access/qhttpnetworkconnection.cpp
@@ -263,7 +263,7 @@ void QHttpNetworkConnectionPrivate::prepareRequest(HttpMessagePair &messagePair)
             request.setContentLength(uploadByteDevice->size());
         } else if (request.contentLength() != -1 && uploadByteDevice->size() == -1) {
             // everything OK, the user supplied us the contentLength
-        } else if (request.contentLength() == -1 && uploadByteDevice->size() == -1) {
+        } else if (Q_UNLIKELY(request.contentLength() == -1 && uploadByteDevice->size() == -1)) {
             qFatal("QHttpNetworkConnectionPrivate: Neither content-length nor upload device size were given");
         }
     }
diff --git a/src/network/access/qnetworkreplyhttpimpl.cpp b/src/network/access/qnetworkreplyhttpimpl.cpp
index 2c31afc225..05457decc4 100644
--- a/src/network/access/qnetworkreplyhttpimpl.cpp
+++ b/src/network/access/qnetworkreplyhttpimpl.cpp
@@ -993,7 +993,7 @@ void QNetworkReplyHttpImplPrivate::initCacheSaveDevice()
         q->connect(cacheSaveDevice, SIGNAL(aboutToClose()), SLOT(_q_cacheSaveDeviceAboutToClose()));
 
     if (!cacheSaveDevice || (cacheSaveDevice && !cacheSaveDevice->isOpen())) {
-        if (cacheSaveDevice && !cacheSaveDevice->isOpen())
+        if (Q_UNLIKELY(cacheSaveDevice && !cacheSaveDevice->isOpen()))
             qCritical("QNetworkReplyImpl: network cache returned a device that is not open -- "
                   "class %s probably needs to be fixed",
                   managerPrivate->networkCache->metaObject()->className());
@@ -2216,7 +2216,7 @@ void QNetworkReplyHttpImplPrivate::setCachingEnabled(bool enable)
         return;                 // nothing to do either!
 
     if (enable) {
-        if (bytesDownloaded) {
+        if (Q_UNLIKELY(bytesDownloaded)) {
             qDebug() << "setCachingEnabled: " << bytesDownloaded << " bytesDownloaded";
             // refuse to enable in this case
             qCritical("QNetworkReplyImpl: backend error: caching was enabled after some bytes had been written");
diff --git a/src/network/access/qnetworkreplyimpl.cpp b/src/network/access/qnetworkreplyimpl.cpp
index 3df39c9bdc..12ecad5ff7 100644
--- a/src/network/access/qnetworkreplyimpl.cpp
+++ b/src/network/access/qnetworkreplyimpl.cpp
@@ -515,7 +515,7 @@ void QNetworkReplyImplPrivate::setCachingEnabled(bool enable)
         return;                 // nothing to do either!
 
     if (enable) {
-        if (bytesDownloaded) {
+        if (Q_UNLIKELY(bytesDownloaded)) {
             // refuse to enable in this case
             qCritical("QNetworkReplyImpl: backend error: caching was enabled after some bytes had been written");
             return;
@@ -604,7 +604,7 @@ void QNetworkReplyImplPrivate::initCacheSaveDevice()
     cacheSaveDevice = networkCache()->prepare(metaData);
 
     if (!cacheSaveDevice || (cacheSaveDevice && !cacheSaveDevice->isOpen())) {
-        if (cacheSaveDevice && !cacheSaveDevice->isOpen())
+        if (Q_UNLIKELY(cacheSaveDevice && !cacheSaveDevice->isOpen()))
             qCritical("QNetworkReplyImpl: network cache returned a device that is not open -- "
                   "class %s probably needs to be fixed",
                   networkCache()->metaObject()->className());
@@ -678,7 +678,7 @@ void QNetworkReplyImplPrivate::appendDownstreamData(QIODevice *data)
         return;
 
     // read until EOF from data
-    if (copyDevice) {
+    if (Q_UNLIKELY(copyDevice)) {
         qCritical("QNetworkReplyImpl: copy from QIODevice already in progress -- "
                   "backend probly needs to be fixed");
         return;
diff --git a/src/opengl/gl2paintengineex/qglengineshadermanager.cpp b/src/opengl/gl2paintengineex/qglengineshadermanager.cpp
index 903f34f939..984590435d 100644
--- a/src/opengl/gl2paintengineex/qglengineshadermanager.cpp
+++ b/src/opengl/gl2paintengineex/qglengineshadermanager.cpp
@@ -188,7 +188,7 @@ QGLEngineSharedShaders::QGLEngineSharedShaders(const QGLContext* context)
 #if defined(QT_DEBUG)
         // Check that all the elements have been filled:
         for (int i = 0; i < TotalSnippetCount; ++i) {
-            if (qShaderSnippets[i] == 0) {
+            if (Q_UNLIKELY(!qShaderSnippets[i])) {
                 qFatal("Shader snippet for %s (#%d) is missing!",
                        snippetNameStr(SnippetName(i)).constData(), i);
             }
@@ -237,11 +237,11 @@ QGLEngineSharedShaders::QGLEngineSharedShaders(const QGLContext* context)
 
     simpleShaderProg->link();
 
-    if (simpleShaderProg->isLinked()) {
+    if (Q_UNLIKELY(!simpleShaderProg->isLinked())) {
+        qCritical("Errors linking simple shader: %s", qPrintable(simpleShaderProg->log()));
+    } else {
         if (!inCache)
             simpleShaderCache.store(simpleShaderProg, context);
-    } else {
-        qCritical("Errors linking simple shader: %s", qPrintable(simpleShaderProg->log()));
     }
 
     // Compile the blit shader:
@@ -278,11 +278,11 @@ QGLEngineSharedShaders::QGLEngineSharedShaders(const QGLContext* context)
     }
 
     blitShaderProg->link();
-    if (blitShaderProg->isLinked()) {
+    if (Q_UNLIKELY(!blitShaderProg->isLinked())) {
+        qCritical("Errors linking blit shader: %s", qPrintable(blitShaderProg->log()));
+    } else {
         if (!inCache)
             blitShaderCache.store(blitShaderProg, context);
-    } else {
-        qCritical("Errors linking blit shader: %s", qPrintable(blitShaderProg->log()));
     }
 
 #ifdef QT_GL_SHARED_SHADER_DEBUG
diff --git a/src/platformsupport/input/libinput/qlibinputhandler.cpp b/src/platformsupport/input/libinput/qlibinputhandler.cpp
index 5aa66a4eaf..58fbaacd2b 100644
--- a/src/platformsupport/input/libinput/qlibinputhandler.cpp
+++ b/src/platformsupport/input/libinput/qlibinputhandler.cpp
@@ -85,18 +85,18 @@ QLibInputHandler::QLibInputHandler(const QString &key, const QString &spec)
     Q_UNUSED(spec);
 
     m_udev = udev_new();
-    if (!m_udev)
+    if (Q_UNLIKELY(!m_udev))
         qFatal("Failed to get udev context for libinput");
 
     m_li = libinput_udev_create_context(&liInterface, Q_NULLPTR, m_udev);
-    if (!m_li)
+    if (Q_UNLIKELY(!m_li))
         qFatal("Failed to get libinput context");
 
     libinput_log_set_handler(m_li, liLogHandler);
     if (qLcLibInput().isDebugEnabled())
         libinput_log_set_priority(m_li, LIBINPUT_LOG_PRIORITY_DEBUG);
 
-    if (libinput_udev_assign_seat(m_li, "seat0"))
+    if (Q_UNLIKELY(libinput_udev_assign_seat(m_li, "seat0")))
         qFatal("Failed to assign seat");
 
     m_liFd = libinput_get_fd(m_li);
diff --git a/src/plugins/platforms/android/androidjnimain.cpp b/src/plugins/platforms/android/androidjnimain.cpp
index d419e42cd5..9a96534c38 100644
--- a/src/plugins/platforms/android/androidjnimain.cpp
+++ b/src/plugins/platforms/android/androidjnimain.cpp
@@ -487,7 +487,7 @@ static jboolean startQtApplication(JNIEnv *env, jobject /*object*/, jstring para
         // Obtain a handle to the main library (the library that contains the main() function).
         // This library should already be loaded, and calling dlopen() will just return a reference to it.
         m_mainLibraryHnd = dlopen(m_applicationParams.first().data(), 0);
-        if (m_mainLibraryHnd == nullptr) {
+        if (Q_UNLIKELY(!m_mainLibraryHnd)) {
             qCritical() << "dlopen failed:" << dlerror();
             return false;
         }
@@ -497,7 +497,7 @@ static jboolean startQtApplication(JNIEnv *env, jobject /*object*/, jstring para
         m_main = (Main)dlsym(RTLD_DEFAULT, "main");
     }
 
-    if (!m_main) {
+    if (Q_UNLIKELY(!m_main)) {
         qCritical() << "dlsym failed:" << dlerror();
         qCritical() << "Could not find main method";
         return false;
diff --git a/src/plugins/platforms/android/qandroidinputcontext.cpp b/src/plugins/platforms/android/qandroidinputcontext.cpp
index e3ea048e84..92c0c2cf0f 100644
--- a/src/plugins/platforms/android/qandroidinputcontext.cpp
+++ b/src/plugins/platforms/android/qandroidinputcontext.cpp
@@ -339,7 +339,7 @@ QAndroidInputContext::QAndroidInputContext()
     : QPlatformInputContext(), m_composingTextStart(-1), m_blockUpdateSelection(false),  m_batchEditNestingLevel(0), m_focusObject(0)
 {
     jclass clazz = QJNIEnvironmentPrivate::findClass(QtNativeInputConnectionClassName);
-    if (clazz == NULL) {
+    if (Q_UNLIKELY(!clazz)) {
         qCritical() << "Native registration unable to find class '"
                     << QtNativeInputConnectionClassName
                     << '\'';
@@ -347,7 +347,7 @@ QAndroidInputContext::QAndroidInputContext()
     }
 
     QJNIEnvironmentPrivate env;
-    if (env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0])) < 0) {
+    if (Q_UNLIKELY(env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0])) < 0)) {
         qCritical() << "RegisterNatives failed for '"
                     << QtNativeInputConnectionClassName
                     << '\'';
@@ -355,7 +355,7 @@ QAndroidInputContext::QAndroidInputContext()
     }
 
     clazz = QJNIEnvironmentPrivate::findClass(QtExtractedTextClassName);
-    if (clazz == NULL) {
+    if (Q_UNLIKELY(!clazz)) {
         qCritical() << "Native registration unable to find class '"
                     << QtExtractedTextClassName
                     << '\'';
@@ -364,43 +364,43 @@ QAndroidInputContext::QAndroidInputContext()
 
     m_extractedTextClass = static_cast<jclass>(env->NewGlobalRef(clazz));
     m_classConstructorMethodID = env->GetMethodID(m_extractedTextClass, "<init>", "()V");
-    if (m_classConstructorMethodID == NULL) {
+    if (Q_UNLIKELY(!m_classConstructorMethodID)) {
         qCritical() << "GetMethodID failed";
         return;
     }
 
     m_partialEndOffsetFieldID = env->GetFieldID(m_extractedTextClass, "partialEndOffset", "I");
-    if (m_partialEndOffsetFieldID == NULL) {
+    if (Q_UNLIKELY(!m_partialEndOffsetFieldID)) {
         qCritical() << "Can't find field partialEndOffset";
         return;
     }
 
     m_partialStartOffsetFieldID = env->GetFieldID(m_extractedTextClass, "partialStartOffset", "I");
-    if (m_partialStartOffsetFieldID == NULL) {
+    if (Q_UNLIKELY(!m_partialStartOffsetFieldID)) {
         qCritical() << "Can't find field partialStartOffset";
         return;
     }
 
     m_selectionEndFieldID = env->GetFieldID(m_extractedTextClass, "selectionEnd", "I");
-    if (m_selectionEndFieldID == NULL) {
+    if (Q_UNLIKELY(!m_selectionEndFieldID)) {
         qCritical() << "Can't find field selectionEnd";
         return;
     }
 
     m_selectionStartFieldID = env->GetFieldID(m_extractedTextClass, "selectionStart", "I");
-    if (m_selectionStartFieldID == NULL) {
+    if (Q_UNLIKELY(!m_selectionStartFieldID)) {
         qCritical() << "Can't find field selectionStart";
         return;
     }
 
     m_startOffsetFieldID = env->GetFieldID(m_extractedTextClass, "startOffset", "I");
-    if (m_startOffsetFieldID == NULL) {
+    if (Q_UNLIKELY(!m_startOffsetFieldID)) {
         qCritical() << "Can't find field startOffset";
         return;
     }
 
     m_textFieldID = env->GetFieldID(m_extractedTextClass, "text", "Ljava/lang/String;");
-    if (m_textFieldID == NULL) {
+    if (Q_UNLIKELY(!m_textFieldID)) {
         qCritical() << "Can't find field text";
         return;
     }
diff --git a/src/plugins/platforms/android/qandroidplatformfontdatabase.cpp b/src/plugins/platforms/android/qandroidplatformfontdatabase.cpp
index a8bbec9400..835ca8a10a 100644
--- a/src/plugins/platforms/android/qandroidplatformfontdatabase.cpp
+++ b/src/plugins/platforms/android/qandroidplatformfontdatabase.cpp
@@ -47,7 +47,7 @@ void QAndroidPlatformFontDatabase::populateFontDatabase()
     QString fontpath = fontDir();
     QDir dir(fontpath);
 
-    if (!dir.exists()) {
+    if (Q_UNLIKELY(!dir.exists())) {
         qFatal("QFontDatabase: Cannot find font directory %s - is Qt installed correctly?",
                qPrintable(fontpath));
     }
diff --git a/src/plugins/platforms/android/qandroidplatformintegration.cpp b/src/plugins/platforms/android/qandroidplatformintegration.cpp
index 2a127f5c3c..23d242a95f 100644
--- a/src/plugins/platforms/android/qandroidplatformintegration.cpp
+++ b/src/plugins/platforms/android/qandroidplatformintegration.cpp
@@ -120,14 +120,14 @@ QAndroidPlatformIntegration::QAndroidPlatformIntegration(const QStringList &para
     m_androidPlatformNativeInterface = new QAndroidPlatformNativeInterface();
 
     m_eglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
-    if (m_eglDisplay == EGL_NO_DISPLAY)
+    if (Q_UNLIKELY(m_eglDisplay == EGL_NO_DISPLAY))
         qFatal("Could not open egl display");
 
     EGLint major, minor;
-    if (!eglInitialize(m_eglDisplay, &major, &minor))
+    if (Q_UNLIKELY(!eglInitialize(m_eglDisplay, &major, &minor)))
         qFatal("Could not initialize egl display");
 
-    if (!eglBindAPI(EGL_OPENGL_ES_API))
+    if (Q_UNLIKELY(!eglBindAPI(EGL_OPENGL_ES_API)))
         qFatal("Could not bind GL_ES API");
 
     m_primaryScreen = new QAndroidPlatformScreen();
diff --git a/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp b/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp
index 57d3bfaf22..85f51d7d29 100644
--- a/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp
+++ b/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp
@@ -175,7 +175,7 @@ void QAndroidPlatformOpenGLWindow::createEgl(EGLConfig config)
     m_androidSurfaceObject = QJNIObjectPrivate();
     m_eglSurface = eglCreateWindowSurface(m_eglDisplay, config, m_nativeWindow, NULL);
     m_format = q_glFormatFromConfig(m_eglDisplay, config, window()->requestedFormat());
-    if (m_eglSurface == EGL_NO_SURFACE) {
+    if (Q_UNLIKELY(m_eglSurface == EGL_NO_SURFACE)) {
         EGLint error = eglGetError();
         eglTerminate(m_eglDisplay);
         qFatal("EGL Error : Could not create the egl surface: error = 0x%x\n", error);
diff --git a/src/plugins/platforms/android/qandroidplatformtheme.cpp b/src/plugins/platforms/android/qandroidplatformtheme.cpp
index 55bef1a1e8..949d31740a 100644
--- a/src/plugins/platforms/android/qandroidplatformtheme.cpp
+++ b/src/plugins/platforms/android/qandroidplatformtheme.cpp
@@ -203,12 +203,12 @@ QJsonObject AndroidStyle::loadStyleData()
 
     QJsonParseError error;
     QJsonDocument document = QJsonDocument::fromJson(f.readAll(), &error);
-    if (document.isNull()) {
+    if (Q_UNLIKELY(document.isNull())) {
         qCritical() << error.errorString();
         return QJsonObject();
     }
 
-    if (!document.isObject()) {
+    if (Q_UNLIKELY(!document.isObject())) {
         qCritical() << "Style.json does not contain a valid style.";
         return QJsonObject();
     }
diff --git a/src/plugins/platforms/direct2d/qwindowsdirect2ddevicecontext.cpp b/src/plugins/platforms/direct2d/qwindowsdirect2ddevicecontext.cpp
index 154023fb11..418c2e3745 100644
--- a/src/plugins/platforms/direct2d/qwindowsdirect2ddevicecontext.cpp
+++ b/src/plugins/platforms/direct2d/qwindowsdirect2ddevicecontext.cpp
@@ -51,7 +51,7 @@ public:
             HRESULT hr = QWindowsDirect2DContext::instance()->d2dDevice()->CreateDeviceContext(
                         D2D1_DEVICE_CONTEXT_OPTIONS_NONE,
                         &deviceContext);
-            if (FAILED(hr))
+            if (Q_UNLIKELY(FAILED(hr)))
                 qFatal("%s: Couldn't create Direct2D Device Context: %#x", __FUNCTION__, hr);
         }
 
diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsintegration.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsintegration.cpp
index d1814fb85d..789f2fa86f 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsintegration.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsintegration.cpp
@@ -77,7 +77,7 @@ void QEglFSKmsIntegration::platformInit()
         qCDebug(qLcEglfsKmsDebug) << "Found the following video devices:" << devices;
         d->deleteLater();
 
-        if (devices.isEmpty())
+        if (Q_UNLIKELY(devices.isEmpty()))
             qFatal("Could not find DRM device!");
 
         m_devicePath = devices.first();
@@ -85,7 +85,7 @@ void QEglFSKmsIntegration::platformInit()
     }
 
     m_device = new QEglFSKmsDevice(this, m_devicePath);
-    if (!m_device->open())
+    if (Q_UNLIKELY(!m_device->open()))
         qFatal("Could not open device %s - aborting!", qPrintable(m_devicePath));
 }
 
diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp
index 1ddcb3b862..b364056b91 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp
@@ -52,20 +52,20 @@ QEglFSKmsEglDeviceIntegration::QEglFSKmsEglDeviceIntegration()
 
 void QEglFSKmsEglDeviceIntegration::platformInit()
 {
-    if (!query_egl_device())
+    if (Q_UNLIKELY(!query_egl_device()))
         qFatal("Could not set up EGL device!");
 
     const char *deviceName = m_funcs->query_device_string(m_egl_device, EGL_DRM_DEVICE_FILE_EXT);
-    if (!deviceName)
+    if (Q_UNLIKELY(!deviceName))
         qFatal("Failed to query device name from EGLDevice");
 
     qCDebug(qLcEglfsKmsDebug, "Opening %s", deviceName);
 
     m_dri_fd = drmOpen(deviceName, Q_NULLPTR);
-    if (m_dri_fd < 0)
+    if (Q_UNLIKELY(m_dri_fd < 0))
         qFatal("Could not open DRM device");
 
-    if (!setup_kms())
+    if (Q_UNLIKELY(!setup_kms()))
         qFatal("Could not set up KMS on device %s!", m_device.constData());
 
     qCDebug(qLcEglfsKmsDebug, "DRM/KMS initialized");
@@ -100,14 +100,14 @@ EGLDisplay QEglFSKmsEglDeviceIntegration::createDisplay(EGLNativeDisplayType nat
         display = eglGetDisplay(nativeDisplay);
     }
 
-    if (display == EGL_NO_DISPLAY)
+    if (Q_UNLIKELY(display == EGL_NO_DISPLAY))
         qFatal("Could not get EGL display");
 
     EGLint major, minor;
-    if (!eglInitialize(display, &major, &minor))
+    if (Q_UNLIKELY(!eglInitialize(display, &major, &minor)))
         qFatal("Could not initialize egl display");
 
-    if (!eglBindAPI(EGL_OPENGL_ES_API))
+    if (Q_UNLIKELY(!eglBindAPI(EGL_OPENGL_ES_API)))
         qFatal("Failed to bind EGL_OPENGL_ES_API\n");
 
     return display;
@@ -255,8 +255,8 @@ QEglFSWindow *QEglFSKmsEglDeviceIntegration::createWindow(QWindow *window) const
     QEglJetsonTK1Window *eglWindow = new QEglJetsonTK1Window(window, this);
 
     m_funcs->initialize(eglWindow->screen()->display());
-    if (!(m_funcs->has_egl_output_base && m_funcs->has_egl_output_drm && m_funcs->has_egl_stream
-          && m_funcs->has_egl_stream_producer_eglsurface && m_funcs->has_egl_stream_consumer_egloutput))
+    if (Q_UNLIKELY(!(m_funcs->has_egl_output_base && m_funcs->has_egl_output_drm && m_funcs->has_egl_stream &&
+                     m_funcs->has_egl_stream_producer_eglsurface && m_funcs->has_egl_stream_consumer_egloutput)))
         qFatal("Required extensions missing!");
 
     return eglWindow;
@@ -298,7 +298,7 @@ void QEglFSKmsEglDeviceIntegration::waitForVSync(QPlatformSurface *) const
                                  -1, 0, 0,
                                  &m_drm_connector->connector_id, 1,
                                  const_cast<const drmModeModeInfoPtr>(&m_drm_mode));
-        if (ret)
+        if (Q_UNLIKELY(ret))
             qFatal("drmModeSetCrtc failed");
     }
 }
@@ -367,7 +367,7 @@ bool QEglFSKmsEglDeviceIntegration::setup_kms()
         }
     }
 
-    if (crtc == 0)
+    if (Q_UNLIKELY(crtc == 0))
         qFatal("No suitable CRTC available");
 
     m_drm_connector = connector;
@@ -387,7 +387,7 @@ bool QEglFSKmsEglDeviceIntegration::setup_kms()
 bool QEglFSKmsEglDeviceIntegration::query_egl_device()
 {
     m_funcs = new QEGLStreamConvenience;
-    if (!m_funcs->has_egl_device_base)
+    if (Q_UNLIKELY(!m_funcs->has_egl_device_base))
         qFatal("EGL_EXT_device_base missing");
 
     EGLint num_devices = 0;
diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_x11/qeglfsx11integration.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_x11/qeglfsx11integration.cpp
index 4d29b96608..ef586622e2 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_x11/qeglfsx11integration.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_x11/qeglfsx11integration.cpp
@@ -172,7 +172,7 @@ void QEglFSX11Integration::sendConnectionEvent(xcb_atom_t a)
 void QEglFSX11Integration::platformInit()
 {
     m_display = XOpenDisplay(0);
-    if (!m_display)
+    if (Q_UNLIKELY(!m_display))
         qFatal("Could not open display");
 
     XSetEventQueueOwner(DISPLAY, XCBOwnsEventQueue);
diff --git a/src/plugins/platforms/eglfs/qeglfsdeviceintegration.cpp b/src/plugins/platforms/eglfs/qeglfsdeviceintegration.cpp
index 064b9f6306..e55a17585e 100644
--- a/src/plugins/platforms/eglfs/qeglfsdeviceintegration.cpp
+++ b/src/plugins/platforms/eglfs/qeglfsdeviceintegration.cpp
@@ -155,7 +155,7 @@ void QEGLDeviceIntegration::platformInit()
 
     framebuffer = qt_safe_open(fbDev, O_RDONLY);
 
-    if (framebuffer == -1) {
+    if (Q_UNLIKELY(framebuffer == -1)) {
         qWarning("EGLFS: Failed to open %s", fbDev.constData());
         qFatal("EGLFS: Can't continue without a display");
     }
diff --git a/src/plugins/platforms/eglfs/qeglfsintegration.cpp b/src/plugins/platforms/eglfs/qeglfsintegration.cpp
index 2086ce56e2..001dd76803 100644
--- a/src/plugins/platforms/eglfs/qeglfsintegration.cpp
+++ b/src/plugins/platforms/eglfs/qeglfsintegration.cpp
@@ -118,11 +118,11 @@ void QEglFSIntegration::initialize()
     qt_egl_device_integration()->platformInit();
 
     m_display = qt_egl_device_integration()->createDisplay(nativeDisplay());
-    if (m_display == EGL_NO_DISPLAY)
+    if (Q_UNLIKELY(m_display == EGL_NO_DISPLAY))
         qFatal("Could not open egl display");
 
     EGLint major, minor;
-    if (!eglInitialize(m_display, &major, &minor))
+    if (Q_UNLIKELY(!eglInitialize(m_display, &major, &minor)))
         qFatal("Could not initialize egl display");
 
     m_inputContext = QPlatformInputContextFactory::create();
diff --git a/src/plugins/platforms/eglfs/qeglfswindow.cpp b/src/plugins/platforms/eglfs/qeglfswindow.cpp
index 8301be8c17..b29981bc98 100644
--- a/src/plugins/platforms/eglfs/qeglfswindow.cpp
+++ b/src/plugins/platforms/eglfs/qeglfswindow.cpp
@@ -102,17 +102,15 @@ void QEglFSWindow::create()
     QEglFSScreen *screen = this->screen();
     QOpenGLCompositor *compositor = QOpenGLCompositor::instance();
     if (screen->primarySurface() != EGL_NO_SURFACE) {
-        if (isRaster() && compositor->targetWindow()) {
-            m_format = compositor->targetWindow()->format();
+        if (Q_UNLIKELY(!isRaster() || !compositor->targetWindow())) {
+#if !defined(Q_OS_ANDROID) || defined(Q_OS_ANDROID_NO_SDK)
+            // We can have either a single OpenGL window or multiple raster windows.
+            // Other combinations cannot work.
+            qFatal("EGLFS: OpenGL windows cannot be mixed with others.");
+#endif
             return;
         }
-
-#if !defined(Q_OS_ANDROID) || defined(Q_OS_ANDROID_NO_SDK)
-        // We can have either a single OpenGL window or multiple raster windows.
-        // Other combinations cannot work.
-        qFatal("EGLFS: OpenGL windows cannot be mixed with others.");
-#endif
-
+        m_format = compositor->targetWindow()->format();
         return;
     }
 
@@ -122,7 +120,7 @@ void QEglFSWindow::create()
 
     resetSurface();
 
-    if (m_surface == EGL_NO_SURFACE) {
+    if (Q_UNLIKELY(m_surface == EGL_NO_SURFACE)) {
         EGLint error = eglGetError();
         eglTerminate(screen->display());
         qFatal("EGL Error : Could not create the egl surface: error = 0x%x\n", error);
@@ -135,7 +133,7 @@ void QEglFSWindow::create()
         context->setShareContext(qt_gl_global_share_context());
         context->setFormat(m_format);
         context->setScreen(window()->screen());
-        if (!context->create())
+        if (Q_UNLIKELY(!context->create()))
             qFatal("EGLFS: Failed to create compositing context");
         compositor->setTarget(context, window());
     }
diff --git a/src/plugins/platforms/haiku/qhaikuwindow.cpp b/src/plugins/platforms/haiku/qhaikuwindow.cpp
index 9622d12111..1576e7c04e 100644
--- a/src/plugins/platforms/haiku/qhaikuwindow.cpp
+++ b/src/plugins/platforms/haiku/qhaikuwindow.cpp
@@ -127,7 +127,7 @@ QHaikuWindow::QHaikuWindow(QWindow *window)
 
     m_window = haikuWindow;
 
-    if (!m_window)
+    if (Q_UNLIKELY(!m_window))
         qFatal("QHaikuWindow: failed to create window");
 
     setGeometry(rect);
diff --git a/src/plugins/platforms/ios/qioseventdispatcher.mm b/src/plugins/platforms/ios/qioseventdispatcher.mm
index 0e9f176487..e1c6071c38 100644
--- a/src/plugins/platforms/ios/qioseventdispatcher.mm
+++ b/src/plugins/platforms/ios/qioseventdispatcher.mm
@@ -129,7 +129,7 @@ namespace
 
             // Which we verify, just in case
             struct rlimit stackLimit = {0, 0};
-            if (getrlimit(RLIMIT_STACK, &stackLimit) == 0 && stackSize > stackLimit.rlim_cur)
+            if (Q_UNLIKELY(getrlimit(RLIMIT_STACK, &stackLimit) == 0 && stackSize > stackLimit.rlim_cur))
                 qFatal("Unexpectedly exceeded stack limit");
 
             return stackSize;
@@ -250,7 +250,7 @@ static void __attribute__((noinline, noreturn)) user_main_trampoline()
         unsigned int bufferSize = [arg lengthOfBytesUsingEncoding:cStringEncoding] + 1;
         argv[i] = reinterpret_cast<char *>(malloc(bufferSize));
 
-        if (![arg getCString:argv[i] maxLength:bufferSize encoding:cStringEncoding])
+        if (Q_UNLIKELY(![arg getCString:argv[i] maxLength:bufferSize encoding:cStringEncoding]))
             qFatal("Could not convert argv[%d] to C string", i);
     }
 
diff --git a/src/plugins/platforms/ios/qiosintegration.mm b/src/plugins/platforms/ios/qiosintegration.mm
index 0e3da8dce8..72c9286f86 100644
--- a/src/plugins/platforms/ios/qiosintegration.mm
+++ b/src/plugins/platforms/ios/qiosintegration.mm
@@ -70,7 +70,7 @@ QIOSIntegration::QIOSIntegration()
     , m_accessibility(0)
     , m_debugWindowManagement(false)
 {
-    if (![UIApplication sharedApplication]) {
+    if (Q_UNLIKELY(![UIApplication sharedApplication])) {
         qFatal("Error: You are creating QApplication before calling UIApplicationMain.\n" \
                "If you are writing a native iOS application, and only want to use Qt for\n" \
                "parts of the application, a good place to create QApplication is from within\n" \
diff --git a/src/plugins/platforms/minimalegl/qminimaleglscreen.cpp b/src/plugins/platforms/minimalegl/qminimaleglscreen.cpp
index 59062338cb..093a1c689c 100644
--- a/src/plugins/platforms/minimalegl/qminimaleglscreen.cpp
+++ b/src/plugins/platforms/minimalegl/qminimaleglscreen.cpp
@@ -74,19 +74,19 @@ QMinimalEglScreen::QMinimalEglScreen(EGLNativeDisplayType display)
 
     EGLint major, minor;
 
-    if (!eglBindAPI(EGL_OPENGL_ES_API)) {
+    if (Q_UNLIKELY(!eglBindAPI(EGL_OPENGL_ES_API))) {
         qWarning("Could not bind GL_ES API\n");
         qFatal("EGL error");
     }
 
     m_dpy = eglGetDisplay(display);
-    if (m_dpy == EGL_NO_DISPLAY) {
+    if (Q_UNLIKELY(m_dpy == EGL_NO_DISPLAY)) {
         qWarning("Could not open egl display\n");
         qFatal("EGL error");
     }
     qWarning("Opened display %p\n", m_dpy);
 
-    if (!eglInitialize(m_dpy, &major, &minor)) {
+    if (Q_UNLIKELY(!eglInitialize(m_dpy, &major, &minor))) {
         qWarning("Could not initialize egl display\n");
         qFatal("EGL error");
     }
@@ -135,9 +135,9 @@ void QMinimalEglScreen::createAndSetPlatformContext()
 
     EGLNativeWindowType eglWindow = 0;
 #ifdef Q_OPENKODE
-    if (kdInitializeNV() == KD_ENOTINITIALIZED) {
+    if (Q_UNLIKELY(kdInitializeNV() == KD_ENOTINITIALIZED))
         qFatal("Did not manage to initialize openkode");
-    }
+
     KDWindow *window = kdCreateWindow(m_dpy,config,0);
 
     kdRealizeWindow(window,&eglWindow);
@@ -148,7 +148,7 @@ void QMinimalEglScreen::createAndSetPlatformContext()
 #endif
 
     m_surface = eglCreateWindowSurface(m_dpy, config, eglWindow, NULL);
-    if (m_surface == EGL_NO_SURFACE) {
+    if (Q_UNLIKELY(m_surface == EGL_NO_SURFACE)) {
         qWarning("Could not create the egl surface: error = 0x%x\n", eglGetError());
         eglTerminate(m_dpy);
         qFatal("EGL error");
diff --git a/src/plugins/platforms/mirclient/qmirclientclipboard.cpp b/src/plugins/platforms/mirclient/qmirclientclipboard.cpp
index aa2ddf2103..4494847b54 100644
--- a/src/plugins/platforms/mirclient/qmirclientclipboard.cpp
+++ b/src/plugins/platforms/mirclient/qmirclientclipboard.cpp
@@ -100,7 +100,7 @@ void QMirClientClipboard::onDBusClipboardGetContentsFinished(QDBusPendingCallWat
     Q_ASSERT(call == mPendingGetContentsCall.data());
 
     QDBusPendingReply<QByteArray> reply = *call;
-    if (reply.isError()) {
+    if (Q_UNLIKELY(reply.isError())) {
         qCritical("QMirClientClipboard - Failed to get system clipboard contents via D-Bus. %s, %s",
                 qPrintable(reply.error().name()), qPrintable(reply.error().message()));
         // TODO: Might try again later a number of times...
@@ -114,7 +114,7 @@ void QMirClientClipboard::onDBusClipboardGetContentsFinished(QDBusPendingCallWat
 void QMirClientClipboard::onDBusClipboardSetContentsFinished(QDBusPendingCallWatcher *call)
 {
     QDBusPendingReply<void> reply = *call;
-    if (reply.isError()) {
+    if (Q_UNLIKELY(reply.isError())) {
         qCritical("QMirClientClipboard - Failed to set the system clipboard contents via D-Bus. %s, %s",
                 qPrintable(reply.error().name()), qPrintable(reply.error().message()));
         // TODO: Might try again later a number of times...
@@ -148,9 +148,8 @@ void QMirClientClipboard::setupDBus()
             "com.canonical.QtMir.Clipboard",
             "ContentsChanged",
             this, SLOT(updateMimeData(QByteArray)));
-    if (!ok) {
+    if (Q_UNLIKELY(!ok))
         qCritical("QMirClientClipboard - Failed to connect to ContentsChanged signal form the D-Bus system clipboard.");
-    }
 
     mDBusClipboard = new QDBusInterface("com.canonical.QtMir",
             "/com/canonical/QtMir/Clipboard",
diff --git a/src/plugins/platforms/mirclient/qmirclientintegration.cpp b/src/plugins/platforms/mirclient/qmirclientintegration.cpp
index a234f4eac6..87d2002c56 100644
--- a/src/plugins/platforms/mirclient/qmirclientintegration.cpp
+++ b/src/plugins/platforms/mirclient/qmirclientintegration.cpp
@@ -95,7 +95,7 @@ QMirClientClientIntegration::QMirClientClientIntegration()
     // Create new application instance
     mInstance = u_application_instance_new_from_description_with_options(mDesc, mOptions);
 
-    if (mInstance == nullptr)
+    if (Q_UNLIKELY(!mInstance))
         qFatal("QMirClientClientIntegration: connection to Mir server failed. Check that a Mir server is\n"
                "running, and the correct socket is being used and is accessible. The shell may have\n"
                "rejected the incoming connection, so check its log file");
diff --git a/src/plugins/platforms/offscreen/qoffscreenintegration_x11.cpp b/src/plugins/platforms/offscreen/qoffscreenintegration_x11.cpp
index eb704f2dfa..dfaaa43c1d 100644
--- a/src/plugins/platforms/offscreen/qoffscreenintegration_x11.cpp
+++ b/src/plugins/platforms/offscreen/qoffscreenintegration_x11.cpp
@@ -143,7 +143,7 @@ static Window createDummyWindow(QOffscreenX11Info *x11, XVisualInfo *visualInfo)
 static Window createDummyWindow(QOffscreenX11Info *x11, GLXFBConfig config)
 {
     XVisualInfo *visualInfo = glXGetVisualFromFBConfig(x11->display(), config);
-    if (!visualInfo)
+    if (Q_UNLIKELY(!visualInfo))
         qFatal("Could not initialize GLX");
     Window window = createDummyWindow(x11, visualInfo);
     XFree(visualInfo);
@@ -177,7 +177,7 @@ QOffscreenX11GLXContext::QOffscreenX11GLXContext(QOffscreenX11Info *x11, QOpenGL
         d->window = createDummyWindow(x11, config);
     } else {
         XVisualInfo *visualInfo = qglx_findVisualInfo(x11->display(), 0, &d->format);
-        if (!visualInfo)
+        if (Q_UNLIKELY(!visualInfo))
             qFatal("Could not initialize GLX");
         d->context = glXCreateContext(x11->display(), visualInfo, d->shareContext, true);
         if (!d->context && d->shareContext) {
diff --git a/src/plugins/platforms/openwfd/qopenwfdport.cpp b/src/plugins/platforms/openwfd/qopenwfdport.cpp
index 8da1e9bd34..c1646fbdf9 100644
--- a/src/plugins/platforms/openwfd/qopenwfdport.cpp
+++ b/src/plugins/platforms/openwfd/qopenwfdport.cpp
@@ -96,9 +96,8 @@ void QOpenWFDPort::attach()
     mPhysicalSize = QSizeF(physicalWFDSize[0],physicalWFDSize[1]);
 
     WFDint numAvailablePipelines = wfdGetPortAttribi(mDevice->handle(),mPort,WFD_PORT_PIPELINE_ID_COUNT);
-    if (!numAvailablePipelines) {
+    if (Q_UNLIKELY(!numAvailablePipelines))
         qFatal("Not possible to make screen that is not possible to create WFPort with no pipline");
-    }
 
     WFDint pipeIds[numAvailablePipelines];
     wfdGetPortAttribiv(mDevice->handle(),mPort,WFD_PORT_BINDABLE_PIPELINE_IDS,numAvailablePipelines,pipeIds);
@@ -109,9 +108,9 @@ void QOpenWFDPort::attach()
             mDevice-> addToUsedPipelineSet(mPipelineId,this);
 
             mPipeline = wfdCreatePipeline(mDevice->handle(),mPipelineId,WFD_NONE);
-            if (mPipeline == WFD_INVALID_HANDLE) {
+            if (Q_UNLIKELY(mPipeline == WFD_INVALID_HANDLE))
                 qFatal("Failed to create pipeline for port %p", this);
-            }
+
             break;
         }
     }
diff --git a/src/plugins/platforms/qnx/qqnxbuffer.cpp b/src/plugins/platforms/qnx/qqnxbuffer.cpp
index 2c3a42ac7c..8589775fdf 100644
--- a/src/plugins/platforms/qnx/qqnxbuffer.cpp
+++ b/src/plugins/platforms/qnx/qqnxbuffer.cpp
@@ -76,7 +76,7 @@ QQnxBuffer::QQnxBuffer(screen_buffer_t buffer)
             screen_get_buffer_property_pv(buffer, SCREEN_PROPERTY_POINTER, (void **)&dataPtr),
             "Failed to query buffer pointer");
 
-    if (dataPtr == 0)
+    if (Q_UNLIKELY(!dataPtr))
         qFatal("QQNX: buffer pointer is NULL, errno=%d", errno);
 
     // Get format of buffer
@@ -131,13 +131,13 @@ void QQnxBuffer::invalidateInCache()
     qBufferDebug() << Q_FUNC_INFO;
 
     // Verify native buffer exists
-    if (m_buffer == 0)
+    if (Q_UNLIKELY(!m_buffer))
         qFatal("QQNX: can't invalidate cache for null buffer");
 
     // Evict buffer's data from cache
     errno = 0;
     int result = msync(m_image.bits(), m_image.height() * m_image.bytesPerLine(), MS_INVALIDATE | MS_CACHE_ONLY);
-    if (result != 0)
+    if (Q_UNLIKELY(result != 0))
         qFatal("QQNX: failed to invalidate cache, errno=%d", errno);
 }
 
diff --git a/src/plugins/platforms/qnx/qqnxeglwindow.cpp b/src/plugins/platforms/qnx/qqnxeglwindow.cpp
index 77630018e9..8faa474718 100644
--- a/src/plugins/platforms/qnx/qqnxeglwindow.cpp
+++ b/src/plugins/platforms/qnx/qqnxeglwindow.cpp
@@ -59,7 +59,7 @@ QQnxEglWindow::QQnxEglWindow(QWindow *window, screen_context_t context, bool nee
     // Set window usage
     const int val = SCREEN_USAGE_OPENGL_ES2;
     const int result = screen_set_window_property_iv(nativeHandle(), SCREEN_PROPERTY_USAGE, &val);
-    if (result != 0)
+    if (Q_UNLIKELY(result != 0))
         qFatal("QQnxEglWindow: failed to set window alpha usage, errno=%d", errno);
 
     m_requestedBufferSize = shouldMakeFullScreen() ? screen()->geometry().size() : window->geometry().size();
@@ -106,7 +106,7 @@ void QQnxEglWindow::destroyEGLSurface()
     // Destroy EGL surface if it exists
     if (m_eglSurface != EGL_NO_SURFACE) {
         EGLBoolean eglResult = eglDestroySurface(platformOpenGLContext()->getEglDisplay(), m_eglSurface);
-        if (eglResult != EGL_TRUE)
+        if (Q_UNLIKELY(eglResult != EGL_TRUE))
             qFatal("QQNX: failed to destroy EGL surface, err=%d", eglGetError());
     }
 
@@ -118,12 +118,12 @@ void QQnxEglWindow::swapEGLBuffers()
     qEglWindowDebug() << Q_FUNC_INFO;
     // Set current rendering API
     EGLBoolean eglResult = eglBindAPI(EGL_OPENGL_ES_API);
-    if (eglResult != EGL_TRUE)
+    if (Q_UNLIKELY(eglResult != EGL_TRUE))
         qFatal("QQNX: failed to set EGL API, err=%d", eglGetError());
 
     // Post EGL surface to window
     eglResult = eglSwapBuffers(m_platformOpenGLContext->getEglDisplay(), m_eglSurface);
-    if (eglResult != EGL_TRUE)
+    if (Q_UNLIKELY(eglResult != EGL_TRUE))
         qFatal("QQNX: failed to swap EGL buffers, err=%d", eglGetError());
 
     windowPosted();
@@ -178,15 +178,15 @@ int QQnxEglWindow::pixelFormat() const
     const QSurfaceFormat format = m_platformOpenGLContext->format();
     // Extract size of color channels from window format
     const int redSize = format.redBufferSize();
-    if (redSize == -1)
+    if (Q_UNLIKELY(redSize == -1))
         qFatal("QQnxWindow: red size not defined");
 
     const int greenSize = format.greenBufferSize();
-    if (greenSize == -1)
+    if (Q_UNLIKELY(greenSize == -1))
         qFatal("QQnxWindow: green size not defined");
 
     const int blueSize = format.blueBufferSize();
-    if (blueSize == -1)
+    if (Q_UNLIKELY(blueSize == -1))
         qFatal("QQnxWindow: blue size not defined");
 
     // select matching native format
diff --git a/src/plugins/platforms/qnx/qqnxglcontext.cpp b/src/plugins/platforms/qnx/qqnxglcontext.cpp
index deac419a36..266de22205 100644
--- a/src/plugins/platforms/qnx/qqnxglcontext.cpp
+++ b/src/plugins/platforms/qnx/qqnxglcontext.cpp
@@ -61,7 +61,7 @@ QQnxGLContext::QQnxGLContext(QOpenGLContext *glContext)
 
     // Set current rendering API
     EGLBoolean eglResult = eglBindAPI(EGL_OPENGL_ES_API);
-    if (eglResult != EGL_TRUE)
+    if (Q_UNLIKELY(eglResult != EGL_TRUE))
         qFatal("QQNX: failed to set EGL API, err=%d", eglGetError());
 
     // Get colour channel sizes from window format
@@ -113,7 +113,7 @@ QQnxGLContext::QQnxGLContext(QOpenGLContext *glContext)
 
     // Select EGL config based on requested window format
     m_eglConfig = q_configFromGLFormat(ms_eglDisplay, format);
-    if (m_eglConfig == 0)
+    if (Q_UNLIKELY(m_eglConfig == 0))
         qFatal("QQnxGLContext: failed to find EGL config");
 
     QQnxGLContext *glShareContext = static_cast<QQnxGLContext*>(m_glContext->shareHandle());
@@ -121,7 +121,7 @@ QQnxGLContext::QQnxGLContext(QOpenGLContext *glContext)
 
     m_eglContext = eglCreateContext(ms_eglDisplay, m_eglConfig, m_eglShareContext,
                                     contextAttrs(format));
-    if (m_eglContext == EGL_NO_CONTEXT) {
+    if (Q_UNLIKELY(m_eglContext == EGL_NO_CONTEXT)) {
         checkEGLError("eglCreateContext");
         qFatal("QQnxGLContext: failed to create EGL context, err=%d", eglGetError());
     }
@@ -170,13 +170,13 @@ void QQnxGLContext::initializeContext()
 
     // Initialize connection to EGL
     ms_eglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
-    if (ms_eglDisplay == EGL_NO_DISPLAY) {
+    if (Q_UNLIKELY(ms_eglDisplay == EGL_NO_DISPLAY)) {
         checkEGLError("eglGetDisplay");
         qFatal("QQnxGLContext: failed to obtain EGL display");
     }
 
     EGLBoolean eglResult = eglInitialize(ms_eglDisplay, 0, 0);
-    if (eglResult != EGL_TRUE) {
+    if (Q_UNLIKELY(eglResult != EGL_TRUE)) {
         checkEGLError("eglInitialize");
         qFatal("QQnxGLContext: failed to initialize EGL display, err=%d", eglGetError());
     }
@@ -198,7 +198,7 @@ bool QQnxGLContext::makeCurrent(QPlatformSurface *surface)
 
     // Set current rendering API
     EGLBoolean eglResult = eglBindAPI(EGL_OPENGL_ES_API);
-    if (eglResult != EGL_TRUE)
+    if (Q_UNLIKELY(eglResult != EGL_TRUE))
         qFatal("QQnxGLContext: failed to set EGL API, err=%d", eglGetError());
 
     QQnxEglWindow *platformWindow = dynamic_cast<QQnxEglWindow*>(surface);
@@ -227,12 +227,12 @@ void QQnxGLContext::doneCurrent()
 
     // set current rendering API
     EGLBoolean eglResult = eglBindAPI(EGL_OPENGL_ES_API);
-    if (eglResult != EGL_TRUE)
+    if (Q_UNLIKELY(eglResult != EGL_TRUE))
         qFatal("QQNX: failed to set EGL API, err=%d", eglGetError());
 
     // clear curent EGL context and unbind EGL surface
     eglResult = eglMakeCurrent(ms_eglDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
-    if (eglResult != EGL_TRUE)
+    if (Q_UNLIKELY(eglResult != EGL_TRUE))
         qFatal("QQNX: failed to clear current EGL context, err=%d", eglGetError());
 }
 
@@ -252,7 +252,7 @@ QFunctionPointer QQnxGLContext::getProcAddress(const QByteArray &procName)
 
     // Set current rendering API
     EGLBoolean eglResult = eglBindAPI(EGL_OPENGL_ES_API);
-    if (eglResult != EGL_TRUE)
+    if (Q_UNLIKELY(eglResult != EGL_TRUE))
         qFatal("QQNX: failed to set EGL API, err=%d", eglGetError());
 
     // Lookup EGL extension function pointer
diff --git a/src/plugins/platforms/qnx/qqnxglobal.cpp b/src/plugins/platforms/qnx/qqnxglobal.cpp
index 01e7675839..4d2599746e 100644
--- a/src/plugins/platforms/qnx/qqnxglobal.cpp
+++ b/src/plugins/platforms/qnx/qqnxglobal.cpp
@@ -44,8 +44,8 @@ void qScreenCheckError(int rc, const char *funcInfo, const char *message, bool c
         rc = screen_flush_context(QQnxIntegration::screenContext(), 0);
     }
 
-    if (rc) {
-        if (critical)
+    if (Q_UNLIKELY(rc)) {
+        if (Q_UNLIKELY(critical))
             qCritical("%s - Screen: %s - Error: %s (%i)", funcInfo, message, strerror(errno), errno);
         else
             qWarning("%s - Screen: %s - Error: %s (%i)", funcInfo, message, strerror(errno), errno);
diff --git a/src/plugins/platforms/qnx/qqnxinputcontext_imf.cpp b/src/plugins/platforms/qnx/qqnxinputcontext_imf.cpp
index ed0db82685..603ddc5c2b 100644
--- a/src/plugins/platforms/qnx/qqnxinputcontext_imf.cpp
+++ b/src/plugins/platforms/qnx/qqnxinputcontext_imf.cpp
@@ -530,29 +530,28 @@ static bool imfAvailable()
 
     if ( p_imf_client_init == 0 ) {
         void *handle = dlopen("libinput_client.so.1", 0);
-        if ( handle ) {
-            p_imf_client_init = (int32_t (*)()) dlsym(handle, "imf_client_init");
-            p_imf_client_disconnect = (void (*)()) dlsym(handle, "imf_client_disconnect");
-            p_ictrl_open_session = (const input_session_t *(*)(connection_interface_t *))dlsym(handle, "ictrl_open_session");
-            p_ictrl_close_session = (void (*)(input_session_t *))dlsym(handle, "ictrl_close_session");
-            p_ictrl_dispatch_event = (int32_t (*)(event_t *))dlsym(handle, "ictrl_dispatch_event");
-            p_vkb_init_selection_service = (int32_t (*)())dlsym(handle, "vkb_init_selection_service");
-            p_ictrl_get_num_active_sessions = (int32_t (*)())dlsym(handle, "ictrl_get_num_active_sessions");
-        } else {
+        if (Q_UNLIKELY(!handle)) {
             qCritical() << Q_FUNC_INFO << "libinput_client.so.1 is not present - IMF services are disabled.";
             s_imfDisabled = true;
             return false;
         }
+        p_imf_client_init = (int32_t (*)()) dlsym(handle, "imf_client_init");
+        p_imf_client_disconnect = (void (*)()) dlsym(handle, "imf_client_disconnect");
+        p_ictrl_open_session = (const input_session_t *(*)(connection_interface_t *))dlsym(handle, "ictrl_open_session");
+        p_ictrl_close_session = (void (*)(input_session_t *))dlsym(handle, "ictrl_close_session");
+        p_ictrl_dispatch_event = (int32_t (*)(event_t *))dlsym(handle, "ictrl_dispatch_event");
+        p_vkb_init_selection_service = (int32_t (*)())dlsym(handle, "vkb_init_selection_service");
+        p_ictrl_get_num_active_sessions = (int32_t (*)())dlsym(handle, "ictrl_get_num_active_sessions");
 
-        if ( p_imf_client_init && p_ictrl_open_session && p_ictrl_dispatch_event ) {
-            s_imfReady = true;
-        } else {
+        if (Q_UNLIKELY(!p_imf_client_init || !p_ictrl_open_session || !p_ictrl_dispatch_event)) {
             p_ictrl_open_session = 0;
             p_ictrl_dispatch_event = 0;
             s_imfDisabled = true;
             qCritical() << Q_FUNC_INFO << "libinput_client.so.1 did not contain the correct symbols, library mismatch? IMF services are disabled.";
             return false;
         }
+
+        s_imfReady = true;
     }
 
     return s_imfReady;
@@ -581,7 +580,7 @@ QQnxInputContext::QQnxInputContext(QQnxIntegration *integration, QQnxAbstractVir
     Q_ASSERT(sInputContextInstance == 0);
     sInputContextInstance = this;
 
-    if (p_imf_client_init() != 0) {
+    if (Q_UNLIKELY(p_imf_client_init() != 0)) {
         s_imfInitFailed = true;
         qCritical("imf_client_init failed - IMF services will be unavailable");
     }
diff --git a/src/plugins/platforms/qnx/qqnxintegration.cpp b/src/plugins/platforms/qnx/qqnxintegration.cpp
index 57f8213a4e..36d59ef134 100644
--- a/src/plugins/platforms/qnx/qqnxintegration.cpp
+++ b/src/plugins/platforms/qnx/qqnxintegration.cpp
@@ -425,7 +425,7 @@ void QQnxIntegration::createDisplays()
                                                 &displayCount);
     Q_SCREEN_CRITICALERROR(result, "Failed to query display count");
 
-    if (displayCount < 1) {
+    if (Q_UNLIKELY(displayCount < 1)) {
         // Never happens, even if there's no display, libscreen returns 1
         qFatal("QQnxIntegration: displayCount=%d", displayCount);
     }
diff --git a/src/plugins/platforms/qnx/qqnxnavigatoreventnotifier.cpp b/src/plugins/platforms/qnx/qqnxnavigatoreventnotifier.cpp
index aa47b5409b..d7221a9185 100644
--- a/src/plugins/platforms/qnx/qqnxnavigatoreventnotifier.cpp
+++ b/src/plugins/platforms/qnx/qqnxnavigatoreventnotifier.cpp
@@ -102,7 +102,7 @@ void QQnxNavigatorEventNotifier::parsePPS(const QByteArray &ppsData, QByteArray
     QList<QByteArray> lines = ppsData.split('\n');
 
     // validate pps object
-    if (lines.size() == 0 || lines.at(0) != "@control")
+    if (Q_UNLIKELY(lines.empty() || lines.at(0) != "@control"))
         qFatal("QQNX: unrecognized pps object, data=%s", ppsData.constData());
 
     // parse pps object attributes and extract values
@@ -160,7 +160,7 @@ void QQnxNavigatorEventNotifier::replyPPS(const QByteArray &res, const QByteArra
     // send pps message to navigator
     errno = 0;
     int bytes = write(m_fd, ppsData.constData(), ppsData.size());
-    if (bytes == -1)
+    if (Q_UNLIKELY(bytes == -1))
         qFatal("QQNX: failed to write navigator pps, errno=%d", errno);
 }
 
@@ -198,7 +198,7 @@ void QQnxNavigatorEventNotifier::readData()
     // attempt to read pps data
     errno = 0;
     int bytes = qt_safe_read(m_fd, buffer, ppsBufferSize - 1);
-    if (bytes == -1)
+    if (Q_UNLIKELY(bytes == -1))
         qFatal("QQNX: failed to read navigator pps, errno=%d", errno);
 
     // check if pps data was received
diff --git a/src/plugins/platforms/qnx/qqnxnavigatorpps.cpp b/src/plugins/platforms/qnx/qqnxnavigatorpps.cpp
index c3b088ae5f..d5bdbb3ec6 100644
--- a/src/plugins/platforms/qnx/qqnxnavigatorpps.cpp
+++ b/src/plugins/platforms/qnx/qqnxnavigatorpps.cpp
@@ -100,7 +100,7 @@ bool QQnxNavigatorPps::sendPpsMessage(const QByteArray &message, const QByteArra
     // send pps message to navigator
     errno = 0;
     int bytes = qt_safe_write(m_fd, ppsMessage.constData(), ppsMessage.size());
-    if (bytes == -1)
+    if (Q_UNLIKELY(bytes == -1))
         qFatal("QQNX: failed to write navigator pps, errno=%d", errno);
 
     // allocate buffer for pps data
@@ -110,7 +110,7 @@ bool QQnxNavigatorPps::sendPpsMessage(const QByteArray &message, const QByteArra
     do {
         errno = 0;
         bytes = qt_safe_read(m_fd, buffer, ppsBufferSize - 1);
-        if (bytes == -1)
+        if (Q_UNLIKELY(bytes == -1))
             qFatal("QQNX: failed to read navigator pps, errno=%d", errno);
     } while (bytes == 0);
 
@@ -125,7 +125,7 @@ bool QQnxNavigatorPps::sendPpsMessage(const QByteArray &message, const QByteArra
     parsePPS(ppsData, responseFields);
 
     if (responseFields.contains("res") && responseFields.value("res") == message) {
-        if (responseFields.contains("err")) {
+        if (Q_UNLIKELY(responseFields.contains("err"))) {
             qCritical() << "navigator responded with error: " << responseFields.value("err");
             return false;
         }
@@ -142,7 +142,7 @@ void QQnxNavigatorPps::parsePPS(const QByteArray &ppsData, QHash<QByteArray, QBy
     QList<QByteArray> lines = ppsData.split('\n');
 
     // validate pps object
-    if (lines.size() == 0 || lines.at(0) != "@control")
+    if (Q_UNLIKELY(lines.empty() || lines.at(0) != "@control"))
         qFatal("QQNX: unrecognized pps object, data=%s", ppsData.constData());
 
     // parse pps object attributes and extract values
diff --git a/src/plugins/platforms/qnx/qqnxrasterwindow.cpp b/src/plugins/platforms/qnx/qqnxrasterwindow.cpp
index 6a346e2bb4..30103b4b9a 100644
--- a/src/plugins/platforms/qnx/qqnxrasterwindow.cpp
+++ b/src/plugins/platforms/qnx/qqnxrasterwindow.cpp
@@ -61,7 +61,7 @@ QQnxRasterWindow::QQnxRasterWindow(QWindow *window, screen_context_t context, bo
 
     const int val = SCREEN_USAGE_NATIVE | SCREEN_USAGE_READ | SCREEN_USAGE_WRITE;
     const int result = screen_set_window_property_iv(nativeHandle(), SCREEN_PROPERTY_USAGE, &val);
-    if (result != 0)
+    if (Q_UNLIKELY(result != 0))
         qFatal("QQnxRasterWindow: failed to set window alpha usage, errno=%d", errno);
 }
 
diff --git a/src/plugins/platforms/qnx/qqnxscreeneventhandler.cpp b/src/plugins/platforms/qnx/qqnxscreeneventhandler.cpp
index 4baabbb4fa..01a54a8a5e 100644
--- a/src/plugins/platforms/qnx/qqnxscreeneventhandler.cpp
+++ b/src/plugins/platforms/qnx/qqnxscreeneventhandler.cpp
@@ -579,12 +579,12 @@ void QQnxScreenEventHandler::handlePropertyEvent(screen_event_t event)
 
     errno = 0;
     screen_window_t window = 0;
-    if (screen_get_event_property_pv(event, SCREEN_PROPERTY_WINDOW, (void**)&window) != 0)
+    if (Q_UNLIKELY(screen_get_event_property_pv(event, SCREEN_PROPERTY_WINDOW, (void**)&window) != 0))
         qFatal("QQnx: failed to query window property, errno=%d", errno);
 
     errno = 0;
     int property;
-    if (screen_get_event_property_iv(event, SCREEN_PROPERTY_NAME, &property) != 0)
+    if (Q_UNLIKELY(screen_get_event_property_iv(event, SCREEN_PROPERTY_NAME, &property) != 0))
         qFatal("QQnx: failed to query window property, errno=%d", errno);
 
     switch (property) {
@@ -601,7 +601,7 @@ void QQnxScreenEventHandler::handleKeyboardFocusPropertyEvent(screen_window_t wi
 {
     errno = 0;
     int focus = 0;
-    if (window && screen_get_window_property_iv(window, SCREEN_PROPERTY_KEYBOARD_FOCUS, &focus) != 0)
+    if (Q_UNLIKELY(window && screen_get_window_property_iv(window, SCREEN_PROPERTY_KEYBOARD_FOCUS, &focus) != 0))
         qFatal("QQnx: failed to query keyboard focus property, errno=%d", errno);
 
     QWindow *focusWindow = QQnxIntegration::window(window);
diff --git a/src/plugins/platforms/qnx/qqnxvirtualkeyboardpps.cpp b/src/plugins/platforms/qnx/qqnxvirtualkeyboardpps.cpp
index 2c7a28e835..33e5cf2947 100644
--- a/src/plugins/platforms/qnx/qqnxvirtualkeyboardpps.cpp
+++ b/src/plugins/platforms/qnx/qqnxvirtualkeyboardpps.cpp
@@ -127,7 +127,7 @@ bool QQnxVirtualKeyboardPps::connect()
     }
 
     m_buffer = new char[ms_bufferSize];
-    if (!m_buffer) {
+    if (Q_UNLIKELY(!m_buffer)) {
         qCritical("QQnxVirtualKeyboard: Unable to allocate buffer of %d bytes. "
                   "Size is unavailable.",  ms_bufferSize);
         return false;
@@ -170,7 +170,7 @@ void QQnxVirtualKeyboardPps::ppsDataReady()
         return;
 
     // nread is the real space necessary, not the amount read.
-    if (static_cast<size_t>(nread) > ms_bufferSize - 1) {
+    if (Q_UNLIKELY(static_cast<size_t>(nread) > ms_bufferSize - 1)) {
         qCritical("QQnxVirtualKeyboard: Keyboard buffer size too short; need %u.", nread + 1);
         connect(); // reconnect
         return;
@@ -184,7 +184,7 @@ void QQnxVirtualKeyboardPps::ppsDataReady()
 #endif
 
     const char *value;
-    if (pps_decoder_get_string(m_decoder, "error", &value) == PPS_DECODER_OK) {
+    if (Q_UNLIKELY(pps_decoder_get_string(m_decoder, "error", &value) == PPS_DECODER_OK)) {
         qCritical("QQnxVirtualKeyboard: Keyboard PPS decoder error: %s", value ? value : "[null]");
         return;
     }
@@ -214,11 +214,11 @@ void QQnxVirtualKeyboardPps::handleKeyboardInfoMessage()
 {
     int newHeight = 0;
 
-    if (pps_decoder_push(m_decoder, "dat") != PPS_DECODER_OK) {
+    if (Q_UNLIKELY(pps_decoder_push(m_decoder, "dat") != PPS_DECODER_OK)) {
         qCritical("QQnxVirtualKeyboard: Keyboard PPS dat object not found");
         return;
     }
-    if (pps_decoder_get_int(m_decoder, "size", &newHeight) != PPS_DECODER_OK) {
+    if (Q_UNLIKELY(pps_decoder_get_int(m_decoder, "size", &newHeight) != PPS_DECODER_OK)) {
         qCritical("QQnxVirtualKeyboard: Keyboard PPS size field not found");
         return;
     }
diff --git a/src/plugins/platforms/qnx/qqnxwindow.cpp b/src/plugins/platforms/qnx/qqnxwindow.cpp
index c081aa6d28..6adc352e2d 100644
--- a/src/plugins/platforms/qnx/qqnxwindow.cpp
+++ b/src/plugins/platforms/qnx/qqnxwindow.cpp
@@ -372,7 +372,7 @@ void QQnxWindow::setBufferSize(const QSize &size)
         screen_get_window_property_iv(m_window, SCREEN_PROPERTY_RENDER_BUFFER_COUNT, &bufferCount),
         "Failed to query render buffer count");
 
-    if (bufferCount != MAX_BUFFER_COUNT) {
+    if (Q_UNLIKELY(bufferCount != MAX_BUFFER_COUNT)) {
         qFatal("QQnxWindow: invalid buffer count. Expected = %d, got = %d.",
                 MAX_BUFFER_COUNT, bufferCount);
     }
@@ -450,10 +450,10 @@ void QQnxWindow::removeFromParent()
     qWindowDebug() << Q_FUNC_INFO << "window =" << window();
     // Remove from old Hierarchy position
     if (m_parentWindow) {
-        if (m_parentWindow->m_childWindows.removeAll(this))
-            m_parentWindow = 0;
-        else
+        if (Q_UNLIKELY(!m_parentWindow->m_childWindows.removeAll(this)))
             qFatal("QQnxWindow: Window Hierarchy broken; window has parent, but parent hasn't got child.");
+        else
+            m_parentWindow = 0;
     } else if (m_screen) {
         m_screen->removeWindow(this);
     }
diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index 5cda6379de..82cc1deb23 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -187,7 +187,7 @@ void QWindowsUser32DLL::init()
     // MinGW (g++ 3.4.5) accepts only C casts.
     setLayeredWindowAttributes = (SetLayeredWindowAttributes)(library.resolve("SetLayeredWindowAttributes"));
     updateLayeredWindow = (UpdateLayeredWindow)(library.resolve("UpdateLayeredWindow"));
-    if (!setLayeredWindowAttributes || !updateLayeredWindow)
+    if (Q_UNLIKELY(!setLayeredWindowAttributes || !updateLayeredWindow))
         qFatal("This version of Windows is not supported (User32.dll is missing the symbols 'SetLayeredWindowAttributes', 'UpdateLayeredWindow').");
 
     updateLayeredWindowIndirect = (UpdateLayeredWindowIndirect)(library.resolve("UpdateLayeredWindowIndirect"));
diff --git a/src/plugins/platforms/windows/qwindowsfontdatabase.cpp b/src/plugins/platforms/windows/qwindowsfontdatabase.cpp
index a30e545807..bb7d0fd8d7 100644
--- a/src/plugins/platforms/windows/qwindowsfontdatabase.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontdatabase.cpp
@@ -1582,7 +1582,7 @@ LOGFONT QWindowsFontDatabase::fontDefToLOGFONT(const QFontDef &request)
     lf.lfPitchAndFamily = DEFAULT_PITCH | hint;
 
     QString fam = request.family;
-    if (fam.size() >= LF_FACESIZE) {
+    if (Q_UNLIKELY(fam.size() >= LF_FACESIZE)) {
         qCritical("%s: Family name '%s' is too long.", __FUNCTION__, qPrintable(fam));
         fam.truncate(LF_FACESIZE - 1);
     }
diff --git a/src/plugins/platforms/windows/qwindowsnativeimage.cpp b/src/plugins/platforms/windows/qwindowsnativeimage.cpp
index 66e64e64b4..56e18e20d7 100644
--- a/src/plugins/platforms/windows/qwindowsnativeimage.cpp
+++ b/src/plugins/platforms/windows/qwindowsnativeimage.cpp
@@ -96,7 +96,7 @@ static inline HBITMAP createDIB(HDC hdc, int width, int height,
     void *bits = 0;
     HBITMAP bitmap = CreateDIBSection(hdc, reinterpret_cast<BITMAPINFO *>(&bmi),
                                       DIB_RGB_COLORS, &bits, 0, 0);
-    if (!bitmap || !bits)
+    if (Q_UNLIKELY(!bitmap || !bits))
         qFatal("%s: CreateDIBSection failed.", __FUNCTION__);
 
     *bitsIn = (uchar*)bits;
diff --git a/src/plugins/platforms/winrt/qwinrteglcontext.cpp b/src/plugins/platforms/winrt/qwinrteglcontext.cpp
index 3fd0278360..1008e1c5e8 100644
--- a/src/plugins/platforms/winrt/qwinrteglcontext.cpp
+++ b/src/plugins/platforms/winrt/qwinrteglcontext.cpp
@@ -55,7 +55,7 @@ struct WinRTEGLDisplay
 {
     WinRTEGLDisplay() {
         eglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
-        if (eglDisplay == EGL_NO_DISPLAY)
+        if (Q_UNLIKELY(eglDisplay == EGL_NO_DISPLAY))
             qCritical("Failed to initialize EGL display: 0x%x", eglGetError());
     }
     ~WinRTEGLDisplay() {
@@ -114,10 +114,10 @@ void QWinRTEGLContext::initialize()
         EGL_NONE,
     };
     g->eglDisplay = eglGetPlatformDisplayEXT(EGL_PLATFORM_ANGLE_ANGLE, EGL_DEFAULT_DISPLAY, displayAttributes);
-    if (g->eglDisplay == EGL_NO_DISPLAY)
+    if (Q_UNLIKELY(g->eglDisplay == EGL_NO_DISPLAY))
         qCritical("Failed to initialize EGL display: 0x%x", eglGetError());
 
-    if (!eglInitialize(g->eglDisplay, nullptr, nullptr))
+    if (Q_UNLIKELY(!eglInitialize(g->eglDisplay, nullptr, nullptr)))
         qCritical("Failed to initialize EGL: 0x%x", eglGetError());
 
     d->eglConfig = q_configFromGLFormat(g->eglDisplay, d->format);
diff --git a/src/plugins/platforms/winrt/qwinrtwindow.cpp b/src/plugins/platforms/winrt/qwinrtwindow.cpp
index bec94c1e51..8a53047d1e 100644
--- a/src/plugins/platforms/winrt/qwinrtwindow.cpp
+++ b/src/plugins/platforms/winrt/qwinrtwindow.cpp
@@ -180,7 +180,7 @@ QWinRTWindow::~QWinRTWindow()
 
     EGLBoolean value = eglDestroySurface(d->display, d->surface);
     d->surface = EGL_NO_SURFACE;
-    if (value == EGL_FALSE)
+    if (Q_UNLIKELY(value == EGL_FALSE))
         qCritical("Failed to destroy EGL window surface: 0x%x", eglGetError());
 }
 
@@ -321,7 +321,7 @@ void QWinRTWindow::createEglSurface(EGLDisplay display, EGLConfig config)
             d->surface = eglCreateWindowSurface(display, config,
                                                 reinterpret_cast<EGLNativeWindowType>(winId()),
                                                 nullptr);
-            if (d->surface == EGL_NO_SURFACE)
+            if (Q_UNLIKELY(d->surface == EGL_NO_SURFACE))
                 qCritical("Failed to create EGL window surface: 0x%x", eglGetError());
             return S_OK;
         });
diff --git a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
index 37f01d4eed..e1fb63fbc4 100644
--- a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
+++ b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
@@ -99,7 +99,7 @@ static Window createDummyWindow(Display *dpy, XVisualInfo *visualInfo, int scree
 static Window createDummyWindow(Display *dpy, GLXFBConfig config, int screenNumber, Window rootWin)
 {
     XVisualInfo *visualInfo = glXGetVisualFromFBConfig(dpy, config);
-    if (!visualInfo)
+    if (Q_UNLIKELY(!visualInfo))
         qFatal("Could not initialize GLX");
     Window window = createDummyWindow(dpy, visualInfo, screenNumber, rootWin);
     XFree(visualInfo);
@@ -301,7 +301,7 @@ void QGLXContext::init(QXcbScreen *screen, QPlatformOpenGLContext *share)
 
         // Note that m_format gets updated with the used surface format
         visualInfo = qglx_findVisualInfo(m_display, screen->screenNumber(), &m_format);
-        if (!visualInfo)
+        if (Q_UNLIKELY(!visualInfo))
             qFatal("Could not initialize GLX");
         m_context = glXCreateContext(m_display, visualInfo, m_shareContext, true);
         if (!m_context && m_shareContext) {
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 50d49ca798..ff39b24e93 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -521,7 +521,7 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     m_connection = xcb_connect(m_displayName.constData(), &m_primaryScreenNumber);
 #endif //XCB_USE_XLIB
 
-    if (!m_connection || xcb_connection_has_error(m_connection))
+    if (Q_UNLIKELY(!m_connection || xcb_connection_has_error(m_connection)))
         qFatal("QXcbConnection: Could not connect to display %s", m_displayName.constData());
 
 
@@ -553,7 +553,7 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     initializeXFixes();
     initializeScreens();
 
-    if (m_screens.isEmpty())
+    if (Q_UNLIKELY(m_screens.isEmpty()))
         qFatal("QXcbConnection: no screens available");
 
     initializeXRender();
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 4bd4639833..3e01a90402 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -395,7 +395,7 @@ void QXcbWindow::create()
         if (!visualInfo)
             visualInfo = static_cast<XVisualInfo *>(createVisual());
 
-        if (!visualInfo && window()->surfaceType() == QSurface::OpenGLSurface)
+        if (Q_UNLIKELY(!visualInfo && window()->surfaceType() == QSurface::OpenGLSurface))
             qFatal("Could not initialize OpenGL");
 
         if (!visualInfo && window()->surfaceType() == QSurface::RasterGLSurface) {
diff --git a/src/printsupport/kernel/qprinter.cpp b/src/printsupport/kernel/qprinter.cpp
index 2cecf61573..734691d504 100644
--- a/src/printsupport/kernel/qprinter.cpp
+++ b/src/printsupport/kernel/qprinter.cpp
@@ -695,7 +695,7 @@ QPrinter::QPrinter(const QPrinterInfo& printer, PrinterMode mode)
 
 void QPrinterPrivate::init(const QPrinterInfo &printer, QPrinter::PrinterMode mode)
 {
-    if (!QCoreApplication::instance()) {
+    if (Q_UNLIKELY(!QCoreApplication::instance())) {
         qFatal("QPrinter: Must construct a QCoreApplication before a QPrinter");
         return;
     }
diff --git a/src/sql/drivers/ibase/qsql_ibase.cpp b/src/sql/drivers/ibase/qsql_ibase.cpp
index b15ba4462d..975c92a116 100644
--- a/src/sql/drivers/ibase/qsql_ibase.cpp
+++ b/src/sql/drivers/ibase/qsql_ibase.cpp
@@ -1910,7 +1910,7 @@ void QIBaseDriver::qHandleEventNotification(void *updatedResultBuffer)
                                     (isc_callback)qEventCallback,
 #endif
                                    eBuffer->resultBuffer);
-            if (status[0] == 1 && status[1]) {
+            if (Q_UNLIKELY(status[0] == 1 && status[1])) {
                 qCritical("QIBaseDriver::qHandleEventNotification: could not resubscribe to '%s'",
                     qPrintable(i.key()));
             }
diff --git a/src/testlib/qbenchmarkvalgrind.cpp b/src/testlib/qbenchmarkvalgrind.cpp
index ada3cfc768..7cb5eef30c 100644
--- a/src/testlib/qbenchmarkvalgrind.cpp
+++ b/src/testlib/qbenchmarkvalgrind.cpp
@@ -96,7 +96,7 @@ qint64 QBenchmarkValgrindUtils::extractResult(const QString &fileName)
             break;
         }
     }
-    if (!valSeen)
+    if (Q_UNLIKELY(!valSeen))
         qFatal("Failed to extract result");
     return val;
 }
diff --git a/src/testlib/qtestcase.cpp b/src/testlib/qtestcase.cpp
index 0847d639fd..f5f399978e 100644
--- a/src/testlib/qtestcase.cpp
+++ b/src/testlib/qtestcase.cpp
@@ -2132,7 +2132,7 @@ public:
             int t = timeout.load();
             if (!t)
                 break;
-            if (!waitCondition.wait(&mutex, t)) {
+            if (Q_UNLIKELY(!waitCondition.wait(&mutex, t))) {
                 stackTrace();
                 qFatal("Test function timed out");
             }
@@ -2256,12 +2256,12 @@ void *fetchData(QTestData *data, const char *tagName, int typeId)
 
     int idx = data->parent()->indexOf(tagName);
 
-    if (idx == -1 || idx >= data->dataCount()) {
+    if (Q_UNLIKELY(idx == -1 || idx >= data->dataCount())) {
         qFatal("QFETCH: Requested testdata '%s' not available, check your _data function.",
                 tagName);
     }
 
-    if (typeId != data->parent()->elementTypeId(idx)) {
+    if (Q_UNLIKELY(typeId != data->parent()->elementTypeId(idx))) {
         qFatal("Requested type '%s' does not match available type '%s'.",
                QMetaType::typeName(typeId),
                QMetaType::typeName(data->parent()->elementTypeId(idx)));
@@ -2940,7 +2940,7 @@ int QTest::qExec(QObject *testObject, int argc, char **argv)
 
 #ifdef QTESTLIB_USE_VALGRIND
     if (QBenchmarkGlobalData::current->mode() == QBenchmarkGlobalData::CallgrindParentProcess) {
-        if (!qApp)
+        if (Q_UNLIKELY(!qApp))
             qFatal("QtTest: -callgrind option is not available with QTEST_APPLESS_MAIN");
 
         const QStringList origAppArgs(QCoreApplication::arguments());
diff --git a/src/testlib/qxctestlogger.mm b/src/testlib/qxctestlogger.mm
index 34116a2670..1e9119c9c0 100644
--- a/src/testlib/qxctestlogger.mm
+++ b/src/testlib/qxctestlogger.mm
@@ -124,7 +124,7 @@ private:
     if (![XCTestProbe isTesting])
         return;
 
-    if (!([NSDate timeIntervalSinceReferenceDate] > 0))
+    if (Q_UNLIKELY(!([NSDate timeIntervalSinceReferenceDate] > 0)))
         qFatal("error: Device date '%s' is bad, likely set to update automatically. Please correct.",
             [[NSDate date] description].UTF8String);
 
diff --git a/src/tools/rcc/main.cpp b/src/tools/rcc/main.cpp
index d8d5728414..1405f19a3a 100644
--- a/src/tools/rcc/main.cpp
+++ b/src/tools/rcc/main.cpp
@@ -304,7 +304,7 @@ int main(int argc, char *argv[])
 {
     // rcc uses a QHash to store files in the resource system.
     // we must force a certain hash order when testing or tst_rcc will fail, see QTBUG-25078
-    if (!qEnvironmentVariableIsEmpty("QT_RCC_TEST") && !qt_qhash_seed.testAndSetRelaxed(-1, 0))
+    if (Q_UNLIKELY(!qEnvironmentVariableIsEmpty("QT_RCC_TEST") && !qt_qhash_seed.testAndSetRelaxed(-1, 0)))
         qFatal("Cannot force QHash seed for testing as requested");
 
     return QT_PREPEND_NAMESPACE(runRcc)(argc, argv);
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 308403175a..fbaa14a2b2 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -289,7 +289,7 @@ QWidgetPrivate::QWidgetPrivate(int version)
       , qd_hd(0)
 #endif
 {
-    if (!qApp) {
+    if (Q_UNLIKELY(!qApp)) {
         qFatal("QWidget: Must construct a QApplication before a QWidget");
         return;
     }
@@ -299,7 +299,7 @@ QWidgetPrivate::QWidgetPrivate(int version)
     // This allows incompatible versions to be loaded, possibly for testing.
     Q_UNUSED(version);
 #else
-    if (version != QObjectPrivateVersion)
+    if (Q_UNLIKELY(version != QObjectPrivateVersion))
         qFatal("Cannot mix incompatible Qt library (version 0x%x) with this library (version 0x%x)",
                 version, QObjectPrivateVersion);
 #endif
@@ -1116,7 +1116,7 @@ void QWidgetPrivate::adjustFlags(Qt::WindowFlags &flags, QWidget *w)
 void QWidgetPrivate::init(QWidget *parentWidget, Qt::WindowFlags f)
 {
     Q_Q(QWidget);
-    if (!qobject_cast<QApplication *>(QCoreApplication::instance()))
+    if (Q_UNLIKELY(!qobject_cast<QApplication *>(QCoreApplication::instance())))
         qFatal("QWidget: Cannot create a QWidget without QApplication");
 
     Q_ASSERT(allWidgets);