Optimized pixmapcache key generation for icons and styles

If we sacrifice the readability we can make cache keys much faster.
Since there is rarely a usecase where we need these as human
readable strings we can take advantage of this fact and remove
almost all memory allocations while still keeping them unique.

Task-number: QTBUG-9850
Reviewed-by: brad

3 files changed, 48 insertions, 65 deletions

diff --git a/src/gui/image/qicon.cpp b/src/gui/image/qicon.cpp
index 891b1db..9f1eea2 100644
--- a/src/gui/image/qicon.cpp
+++ b/src/gui/image/qicon.cpp
@@ -261,16 +261,19 @@ QPixmap QPixmapIconEngine::pixmap(const QSize &size, QIcon::Mode mode, QIcon::St
     if (!actualSize.isNull() && (actualSize.width() > size.width() || actualSize.height() > size.height()))
         actualSize.scale(size, Qt::KeepAspectRatio);
 
-    QString key = QLatin1String("$qt_icon_")
-                  + QString::number(pm.cacheKey())
-                  + QString::number(pe->mode)
-                  + QString::number(QApplication::palette().cacheKey())
-                  + QLatin1Char('_')
-                  + QString::number(actualSize.width())
-                  + QLatin1Char('_')
-                  + QString::number(actualSize.height())
-                  + QLatin1Char('_');
-
+    int digits = sizeof(qint64)/sizeof(QChar);
+    quint64 tkey = pm.cacheKey(),
+            tmode = pe->mode,
+            tpalkey = QApplication::palette().cacheKey(),
+            twidth = actualSize.width(),
+            theight = actualSize.height();
+
+    QString key = QLatin1Literal("qt_")
+                  % QString::fromRawData((QChar*)&tkey, digits)
+                  % QString::fromRawData((QChar*)&tmode, digits)
+                  % QString::fromRawData((QChar*)&tpalkey, digits)
+                  % QString::fromRawData((QChar*)&twidth, digits)
+                  % QString::fromRawData((QChar*)&theight, digits);
 
     if (mode == QIcon::Active) {
         if (QPixmapCache::find(key + QString::number(mode), pm))
diff --git a/src/gui/styles/qgtkpainter.cpp b/src/gui/styles/qgtkpainter.cpp
index 1f68f2f..a6686e2 100644
--- a/src/gui/styles/qgtkpainter.cpp
+++ b/src/gui/styles/qgtkpainter.cpp
@@ -154,9 +154,21 @@ QGtkPainter::QGtkPainter(QPainter *_painter)
 static QString uniqueName(const QString &key, GtkStateType state, GtkShadowType shadow,
                           const QSize &size, GtkWidget *widget = 0)
 {
+
+    int digits = sizeof(qint64)/sizeof(QChar);
+    quint64 tstate= state,
+            tshadow = shadow,
+            twidth = size.width(),
+            theight = size.height(),
+            twidget = quint64(widget);
+
     // Note the widget arg should ideally use the widget path, though would compromise performance
-    QString tmp = QString(QLS("%0-%1-%2-%3x%4-%5")).arg(key).arg(uint(state)).arg(shadow)
-                          .arg(size.width()).arg(size.height()).arg(quintptr(widget));
+    QString tmp = key
+                  % QString::fromRawData((QChar*)&tstate, digits)
+                  % QString::fromRawData((QChar*)&tshadow, digits)
+                  % QString::fromRawData((QChar*)&twidth, digits)
+                  % QString::fromRawData((QChar*)&theight, digits)
+                  % QString::fromRawData((QChar*)&twidget, digits);
     return tmp;
 }
 
diff --git a/src/gui/styles/qstylehelper.cpp b/src/gui/styles/qstylehelper.cpp
index 296c51c..22f2014 100644
--- a/src/gui/styles/qstylehelper.cpp
+++ b/src/gui/styles/qstylehelper.cpp
@@ -58,67 +58,35 @@
 
 QT_BEGIN_NAMESPACE
 
-// internal helper. Converts an integer value to an unique string token
-template <typename T>
-struct HexString
-{
-    inline HexString(const T t)
-        : val(t)
-    {}
-
-    inline void write(QChar *&dest) const
-    {
-        const ushort hexChars[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
-        const char *c = reinterpret_cast<const char *>(&val);
-        for (uint i = 0; i < sizeof(T); ++i) {
-            *dest++ = hexChars[*c & 0xf];
-            *dest++ = hexChars[(*c & 0xf0) >> 4];
-            ++c;
-        }
-    }
-
-    const T val;
-};
-
-// specialization to enable fast concatenating of our string tokens to a string
-template <typename T>
-struct QConcatenable<HexString<T> >
-{
-    typedef HexString<T> type;
-    enum { ExactSize = true };
-    static int size(const HexString<T> &str) { return sizeof(str.val) * 2; }
-    static inline void appendTo(const HexString<T> &str, QChar *&out) { str.write(out); }
-};
-
 namespace QStyleHelper {
 
 QString uniqueName(const QString &key, const QStyleOption *option, const QSize &size)
 {
     const QStyleOptionComplex *complexOption = qstyleoption_cast<const QStyleOptionComplex *>(option);
-
-    QString tmp = key
-                  % QLatin1Char('-')
-                  % HexString<uint>(option->state)
-                  % QLatin1Char('-')
-                  % HexString<uint>(option->direction)
-                  % QLatin1Char('-')
-                  % HexString<uint>(complexOption ? uint(complexOption->activeSubControls) : 0u)
-                  % QLatin1Char('-')
-                  % HexString<quint64>(option->palette.cacheKey())
-                  % QLatin1Char('-')
-                  % HexString<uint>(size.width())
-                  % QLatin1Char('x')
-                  % HexString<uint>(size.height());
+    int digits = sizeof(qint64)/sizeof(QChar);
+    quint64 state = option->state,
+            direction = option->direction,
+            subcontrols = (complexOption ? uint(complexOption->activeSubControls) : 0u),
+            palettekey = option->palette.cacheKey(),
+            width = size.width(),
+            height = size.height();
+
+    QString tmp = key % QString::fromRawData((QChar*)&state, digits)
+                      % QString::fromRawData((QChar*)&direction, digits)
+                      % QString::fromRawData((QChar*)&subcontrols, digits)
+                      % QString::fromRawData((QChar*)&palettekey, digits)
+                      % QString::fromRawData((QChar*)&width, digits)
+                      % QString::fromRawData((QChar*)&height, digits);
 
 #ifndef QT_NO_SPINBOX
     if (const QStyleOptionSpinBox *spinBox = qstyleoption_cast<const QStyleOptionSpinBox *>(option)) {
-        tmp = tmp
-              % QLatin1Char('-')
-              % HexString<uint>(spinBox->buttonSymbols)
-              % QLatin1Char('-')
-              % HexString<uint>(spinBox->stepEnabled)
-              % QLatin1Char('-')
-              % QLatin1Char(spinBox->frame ? '1' : '0');
+        quint64 buttonsymbols = spinBox->buttonSymbols,
+                stepEnabled = spinBox->stepEnabled,
+                frame = spinBox->frame;
+
+        tmp = tmp % QString::fromRawData((QChar*)&buttonsymbols, digits)
+                  % QString::fromRawData((QChar*)&stepEnabled, digits)
+                  % QString::fromRawData((QChar*)&frame, digits);
     }
 #endif // QT_NO_SPINBOX
     return tmp;