QTime: optimize toString()

Instead of using a QString::arg() cascade, which creates tons of
temporaries, use good 'ol sprintf().

Effects on Linux GCC 4.9 stripped release builds:
 text   -308B
 data    +-0B
 relocs  +-0

Change-Id: I348577491d1399b5040f7ed9e9f6b111a9528e5d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 1 insertions, 3 deletions

diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 8c25994bb2..7d1ed9d2ba 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -1569,9 +1569,7 @@ QString QTime::toString(Qt::DateFormat format) const
     case Qt::ISODate:
     case Qt::TextDate:
     default:
-        return QString::fromLatin1("%1:%2:%3").arg(hour(), 2, 10, QLatin1Char('0'))
-                                              .arg(minute(), 2, 10, QLatin1Char('0'))
-                                              .arg(second(), 2, 10, QLatin1Char('0'));
+        return QString::asprintf("%02d:%02d:%02d", hour(), minute(), second());
     }
 }