Use Q_UNLIKELY for every qFatal()/qCritical()

If, after checking a condition, we issue a qFatal()
or a qCritical(), by definition that check is
unlikely to be true.

Tell the compiler so it can move the error handling
code out of the normal code path to increase the
effective icache size.

Moved conditional code around where possible so that
we could always use Q_UNLIKELY, instead of having to
revert to Q_LIKELY here and there.

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

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

1 files changed, 4 insertions, 4 deletions

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