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>

3 files changed, 5 insertions, 5 deletions

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) {