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, 8 insertions, 8 deletions

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) {