Make some atomic counters zero-based

A variable of static storage duration that is not zero-initialized
takes up space in the DATA segment of the executable. By making the
counters start at zero and adding the initial value afterwards, we
move them over to the BSS segment, which does not take up space in
the executable.

Wrap atomics used across function boundaries into small functions,
to avoid code duplication and to increase readability.

Change-Id: Ida6ed316ecb8fe20da62a9577161349e14de5aed
Reviewed-by: Thiago Macieira <[email protected]>

9 files changed, 48 insertions, 21 deletions

diff --git a/src/corelib/plugin/quuid.cpp b/src/corelib/plugin/quuid.cpp
index f11ac6548b6..1a7073a0698 100644
--- a/src/corelib/plugin/quuid.cpp
+++ b/src/corelib/plugin/quuid.cpp
@@ -968,10 +968,10 @@ QUuid QUuid::createUuid()
         if (!uuidseed.hasLocalData())
         {
             int *pseed = new int;
-            static QBasicAtomicInt serial = Q_BASIC_ATOMIC_INITIALIZER(2);
+            static QBasicAtomicInt serial;
             qsrand(*pseed = QDateTime::currentSecsSinceEpoch()
                    + quintptr(&pseed)
-                   + serial.fetchAndAddRelaxed(1));
+                   + 2 + serial.fetchAndAddRelaxed(1));
             uuidseed.setLocalData(pseed);
         }
 #else
diff --git a/src/gui/image/qicon.cpp b/src/gui/image/qicon.cpp
index 17734f05f3f..0c3323636ad 100644
--- a/src/gui/image/qicon.cpp
+++ b/src/gui/image/qicon.cpp
@@ -97,7 +97,11 @@ QT_BEGIN_NAMESPACE
   \value On  Display the pixmap when the widget is in an "on" state
 */
 
-static QBasicAtomicInt serialNumCounter = Q_BASIC_ATOMIC_INITIALIZER(1);
+static int nextSerialNumCounter()
+{
+    static QBasicAtomicInt serial;
+    return 1 + serial.fetchAndAddRelaxed(1);
+}
 
 static void qt_cleanup_icon_cache();
 namespace {
@@ -139,7 +143,7 @@ static qreal qt_effective_device_pixel_ratio(QWindow *window = 0)
 
 QIconPrivate::QIconPrivate(QIconEngine *e)
     : engine(e), ref(1),
-    serialNum(serialNumCounter.fetchAndAddRelaxed(1)),
+      serialNum(nextSerialNumCounter()),
     detach_no(0),
     is_mask(false)
 {
diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index 9870e19cec6..75229ada6c5 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -89,12 +89,16 @@ static QImage rotated90(const QImage &src);
 static QImage rotated180(const QImage &src);
 static QImage rotated270(const QImage &src);
 
-QBasicAtomicInt qimage_serial_number = Q_BASIC_ATOMIC_INITIALIZER(1);
+static int next_qimage_serial_number()
+{
+    static QBasicAtomicInt serial;
+    return 1 + serial.fetchAndAddRelaxed(1);
+}
 
 QImageData::QImageData()
     : ref(0), width(0), height(0), depth(0), nbytes(0), devicePixelRatio(1.0), data(0),
       format(QImage::Format_ARGB32), bytes_per_line(0),
-      ser_no(qimage_serial_number.fetchAndAddRelaxed(1)),
+      ser_no(next_qimage_serial_number()),
       detach_no(0),
       dpmx(qt_defaultDpiX() * 100 / qreal(2.54)),
       dpmy(qt_defaultDpiY() * 100 / qreal(2.54)),
diff --git a/src/gui/opengl/qopengltextureglyphcache.cpp b/src/gui/opengl/qopengltextureglyphcache.cpp
index 62b069a1d08..9a4527b4e61 100644
--- a/src/gui/opengl/qopengltextureglyphcache.cpp
+++ b/src/gui/opengl/qopengltextureglyphcache.cpp
@@ -47,7 +47,11 @@
 QT_BEGIN_NAMESPACE
 
 
-QBasicAtomicInt qopengltextureglyphcache_serial_number = Q_BASIC_ATOMIC_INITIALIZER(1);
+static int next_qopengltextureglyphcache_serial_number()
+{
+    static QBasicAtomicInt serial;
+    return 1 + serial.fetchAndAddRelaxed(1);
+}
 
 QOpenGLTextureGlyphCache::QOpenGLTextureGlyphCache(QFontEngine::GlyphFormat format, const QTransform &matrix)
     : QImageTextureGlyphCache(format, matrix)
@@ -55,7 +59,7 @@ QOpenGLTextureGlyphCache::QOpenGLTextureGlyphCache(QFontEngine::GlyphFormat form
     , pex(0)
     , m_blitProgram(0)
     , m_filterMode(Nearest)
-    , m_serialNumber(qopengltextureglyphcache_serial_number.fetchAndAddRelaxed(1))
+    , m_serialNumber(next_qopengltextureglyphcache_serial_number())
     , m_buffer(QOpenGLBuffer::VertexBuffer)
 {
 #ifdef QT_GL_TEXTURE_GLYPH_CACHE_DEBUG
diff --git a/src/network/access/qftp.cpp b/src/network/access/qftp.cpp
index 52b9dd91692..18c5a16cb58 100644
--- a/src/network/access/qftp.cpp
+++ b/src/network/access/qftp.cpp
@@ -246,22 +246,25 @@ public:
     } data;
     bool is_ba;
 
-    static QBasicAtomicInt idCounter;
 };
 
-QBasicAtomicInt QFtpCommand::idCounter = Q_BASIC_ATOMIC_INITIALIZER(1);
+static int nextId()
+{
+    static QBasicAtomicInt counter;
+    return 1 + counter.fetchAndAddRelaxed(1);
+}
 
 QFtpCommand::QFtpCommand(QFtp::Command cmd, const QStringList &raw, const QByteArray &ba)
     : command(cmd), rawCmds(raw), is_ba(true)
 {
-    id = idCounter.fetchAndAddRelaxed(1);
+    id = nextId();
     data.ba = new QByteArray(ba);
 }
 
 QFtpCommand::QFtpCommand(QFtp::Command cmd, const QStringList &raw, QIODevice *dev)
     : command(cmd), rawCmds(raw), is_ba(false)
 {
-    id = idCounter.fetchAndAddRelaxed(1);
+    id = nextId();
     data.dev = dev;
 }
 
diff --git a/src/network/kernel/qhostinfo.cpp b/src/network/kernel/qhostinfo.cpp
index 193c990d8c3..d3a1858f861 100644
--- a/src/network/kernel/qhostinfo.cpp
+++ b/src/network/kernel/qhostinfo.cpp
@@ -183,7 +183,11 @@ void emit_results_ready(const QHostInfo &hostInfo, const QObject *receiver,
     \sa QAbstractSocket, {http://www.rfc-editor.org/rfc/rfc3492.txt}{RFC 3492}
 */
 
-static QBasicAtomicInt theIdCounter = Q_BASIC_ATOMIC_INITIALIZER(1);
+static int nextId()
+{
+    static QBasicAtomicInt counter;
+    return 1 + counter.fetchAndAddRelaxed(1);
+}
 
 /*!
     Looks up the IP address(es) associated with host name \a name, and
@@ -229,7 +233,7 @@ int QHostInfo::lookupHost(const QString &name, QObject *receiver,
 
     qRegisterMetaType<QHostInfo>();
 
-    int id = theIdCounter.fetchAndAddRelaxed(1); // generate unique ID
+    int id = nextId(); // generate unique ID
 
     if (name.isEmpty()) {
         if (!receiver)
@@ -596,7 +600,7 @@ int QHostInfo::lookupHostImpl(const QString &name,
 
     qRegisterMetaType<QHostInfo>();
 
-    int id = theIdCounter.fetchAndAddRelaxed(1); // generate unique ID
+    int id = nextId(); // generate unique ID
 
     if (Q_UNLIKELY(name.isEmpty())) {
         QHostInfo hostInfo(id);
diff --git a/src/network/socket/qsocks5socketengine.cpp b/src/network/socket/qsocks5socketengine.cpp
index 95a0d0563a3..2847b910f37 100644
--- a/src/network/socket/qsocks5socketengine.cpp
+++ b/src/network/socket/qsocks5socketengine.cpp
@@ -1002,13 +1002,17 @@ QSocks5SocketEngine::~QSocks5SocketEngine()
         delete d->bindData;
 }
 
-static QBasicAtomicInt descriptorCounter = Q_BASIC_ATOMIC_INITIALIZER(1);
+static int nextDescriptor()
+{
+    static QBasicAtomicInt counter;
+    return 1 + counter.fetchAndAddRelaxed(1);
+}
 
 bool QSocks5SocketEngine::initialize(QAbstractSocket::SocketType type, QAbstractSocket::NetworkLayerProtocol protocol)
 {
     Q_D(QSocks5SocketEngine);
 
-    d->socketDescriptor = descriptorCounter.fetchAndAddRelaxed(1);
+    d->socketDescriptor = nextDescriptor();
 
     d->socketType = type;
     d->socketProtocol = protocol;
diff --git a/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp b/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
index 047b681bcb8..c1c5661da4c 100644
--- a/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
+++ b/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
@@ -45,7 +45,11 @@
 QT_BEGIN_NAMESPACE
 
 
-QBasicAtomicInt qgltextureglyphcache_serial_number = Q_BASIC_ATOMIC_INITIALIZER(1);
+static int next_qgltextureglyphcache_serial_number()
+{
+    static QBasicAtomicInt serial;
+    return 1 + serial.fetchAndAddRelaxed(1);
+}
 
 QGLTextureGlyphCache::QGLTextureGlyphCache(QFontEngine::GlyphFormat format, const QTransform &matrix)
     : QImageTextureGlyphCache(format, matrix)
@@ -53,7 +57,7 @@ QGLTextureGlyphCache::QGLTextureGlyphCache(QFontEngine::GlyphFormat format, cons
     , pex(0)
     , m_blitProgram(0)
     , m_filterMode(Nearest)
-    , m_serialNumber(qgltextureglyphcache_serial_number.fetchAndAddRelaxed(1))
+    , m_serialNumber(next_qgltextureglyphcache_serial_number())
 {
 #ifdef QT_GL_TEXTURE_GLYPH_CACHE_DEBUG
     qDebug(" -> QGLTextureGlyphCache() %p for context %p.", this, QOpenGLContext::currentContext());
diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_emu/qeglfsemulatorintegration.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_emu/qeglfsemulatorintegration.cpp
index 8a059ba973a..d0b4b5d5bd5 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_emu/qeglfsemulatorintegration.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_emu/qeglfsemulatorintegration.cpp
@@ -122,13 +122,13 @@ EGLNativeWindowType QEglFSEmulatorIntegration::createNativeWindow(QPlatformWindo
 {
     Q_UNUSED(size);
     Q_UNUSED(format);
-    static QAtomicInt uniqueWindowId(1);
     QEglFSEmulatorScreen *screen = static_cast<QEglFSEmulatorScreen *>(platformWindow->screen());
     if (screen && setDisplay) {
         // Let the emulator know which screen the window surface is attached to
         setDisplay(screen->id());
     }
-    return EGLNativeWindowType(qintptr(uniqueWindowId.fetchAndAddRelaxed(1)));
+    static QBasicAtomicInt uniqueWindowId;
+    return EGLNativeWindowType(qintptr(1 + uniqueWindowId.fetchAndAddRelaxed(1)));
 }
 
 QT_END_NAMESPACE