Avoid unnecessary creation of some Q_GLOBAL_STATIC

If these lists weren't created in the first place, then they are empty.
We don't need to create it in order to conclude that. Unlike most
Q_GLOBAL_STATICS, these are almost never used and yet they were
always created due to where they were checked.

Since we're calling exists() before, there are two consequences: first,
since the list already exists, we're not allocating memory so it cannot
throw std::bad_alloc when being accessed. Second, since we've just
checked it exists, we can use QGlobalStatic's operator*(), which is
slightly faster than operator()(). The weird &(*list) syntax is only to
avoid changing the rest of the code that used a pointer

Change-Id: Ifaee7464122d402991b6fffd14a0e44f533dc3d9
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

2 files changed, 10 insertions, 12 deletions

diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp
index bc6560ddae..54df8b1f61 100644
--- a/src/corelib/global/qglobal.cpp
+++ b/src/corelib/global/qglobal.cpp
@@ -4027,7 +4027,10 @@ bool QInternal::activateCallbacks(Callback cb, void **parameters)
 {
     Q_ASSERT_X(cb >= 0, "QInternal::activateCallback()", "Callback id must be a valid id");
 
-    QInternal_CallBackTable *cbt = global_callback_table();
+    if (!global_callback_table.exists())
+        return false;
+
+    QInternal_CallBackTable *cbt = &(*global_callback_table);
     if (cbt && cb < cbt->callbacks.size()) {
         QList<qInternalCallback> callbacks = cbt->callbacks[cb];
         bool ret = false;
diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 96167b4508..c5f2e71f8c 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -270,12 +270,13 @@ void qRemovePostRoutine(QtCleanUpFunction p)
 
 static void qt_call_pre_routines()
 {
-    QStartUpFuncList *list = preRList();
-    if (!list)
+    if (!preRList.exists())
         return;
+
 #ifndef QT_NO_THREAD
     QMutexLocker locker(&globalPreRoutinesMutex);
 #endif
+    QVFuncList *list = &(*preRList);
     // Unlike qt_call_post_routines, we don't empty the list, because
     // Q_COREAPP_STARTUP_FUNCTION is a macro, so the user expects
     // the function to be executed every time QCoreApplication is created.
@@ -285,16 +286,10 @@ static void qt_call_pre_routines()
 
 void Q_CORE_EXPORT qt_call_post_routines()
 {
-    QVFuncList *list = 0;
-    QT_TRY {
-        list = postRList();
-    } QT_CATCH(const std::bad_alloc &) {
-        // ignore - if we can't allocate a post routine list,
-        // there's a high probability that there's no post
-        // routine to be executed :)
-    }
-    if (!list)
+    if (!postRList.exists())
         return;
+
+    QVFuncList *list = &(*postRList);
     while (!list->isEmpty())
         (list->takeFirst())();
 }