From 54255f7c5e7cecc58076c412183ce2d877a34c18 Mon Sep 17 00:00:00 2001
From: "Bradley T. Hughes" <bradley.hughes@nokia.com>
Date: Fri, 9 Sep 2011 11:07:48 +0200
Subject: Make QVectorData::shared_null const

Similar to QByteArray and QString, keep the shared_null in shareable
memory and never modify it.

Since QRegion uses the internals of QVector, we need to make sure that
QRegion also never modifies the shared_null.

Change-Id: I809e5873fe414138f97d501e05458b73c04b18fb
Reviewed-on: http://codereview.qt-project.org/4529
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
---
 src/corelib/tools/qvector.cpp |  2 +-
 src/corelib/tools/qvector.h   | 10 +++++-----
 src/gui/painting/qregion.cpp  |  3 ++-
 3 files changed, 8 insertions(+), 7 deletions(-)

(limited to 'src')

diff --git a/src/corelib/tools/qvector.cpp b/src/corelib/tools/qvector.cpp
index 98a2412347..e1828c2b0f 100644
--- a/src/corelib/tools/qvector.cpp
+++ b/src/corelib/tools/qvector.cpp
@@ -52,7 +52,7 @@ static inline int alignmentThreshold()
     return 2 * sizeof(void*);
 }
 
-QVectorData QVectorData::shared_null = { Q_BASIC_ATOMIC_INITIALIZER(1), 0, 0, true, false, 0 };
+const QVectorData QVectorData::shared_null = { Q_REFCOUNT_INITIALIZER(-1), 0, 0, true, false, 0 };
 
 QVectorData *QVectorData::malloc(int sizeofTypedData, int size, int sizeofT, QVectorData *init)
 {
diff --git a/src/corelib/tools/qvector.h b/src/corelib/tools/qvector.h
index 5c25266ede..34d1ed3717 100644
--- a/src/corelib/tools/qvector.h
+++ b/src/corelib/tools/qvector.h
@@ -42,10 +42,10 @@
 #ifndef QVECTOR_H
 #define QVECTOR_H
 
-#include <QtCore/qiterator.h>
-#include <QtCore/qatomic.h>
 #include <QtCore/qalgorithms.h>
+#include <QtCore/qiterator.h>
 #include <QtCore/qlist.h>
+#include <QtCore/qrefcount.h>
 
 #ifndef QT_NO_STL
 #include <iterator>
@@ -65,7 +65,7 @@ QT_MODULE(Core)
 
 struct Q_CORE_EXPORT QVectorData
 {
-    QBasicAtomicInt ref;
+    QtPrivate::RefCount ref;
     int alloc;
     int size;
 #if defined(QT_ARCH_SPARC) && defined(Q_CC_GNU) && defined(__LP64__) && defined(QT_BOOTSTRAPPED)
@@ -79,7 +79,7 @@ struct Q_CORE_EXPORT QVectorData
     uint reserved : 30;
 #endif
 
-    static QVectorData shared_null;
+    static const QVectorData shared_null;
     // ### Qt 5: rename to 'allocate()'. The current name causes problems for
     // some debugges when the QVector is member of a class within an unnamed namespace.
     // ### Qt 5: can be removed completely. (Ralf)
@@ -117,7 +117,7 @@ class QVector
 public:
     // ### Qt 5: Consider making QVector non-shared to get at least one
     // "really fast" container. See tests/benchmarks/corelib/tools/qvector/
-    inline QVector() : d(&QVectorData::shared_null) { d->ref.ref(); }
+    inline QVector() : d(const_cast<QVectorData *>(&QVectorData::shared_null)) { }
     explicit QVector(int size);
     QVector(int size, const T &t);
     inline QVector(const QVector<T> &v) : d(v.d) { d->ref.ref(); if (!d->sharable) detach_helper(); }
diff --git a/src/gui/painting/qregion.cpp b/src/gui/painting/qregion.cpp
index d3a43c4193..f343fa9b4c 100644
--- a/src/gui/painting/qregion.cpp
+++ b/src/gui/painting/qregion.cpp
@@ -4268,7 +4268,8 @@ QVector<QRect> QRegion::rects() const
     if (d->qt_rgn) {
         d->qt_rgn->vectorize();
         // hw: modify the vector size directly to avoid reallocation
-        d->qt_rgn->rects.d->size = d->qt_rgn->numRects;
+        if (d->qt_rgn->rects.d != &QVectorData::shared_null)
+            d->qt_rgn->rects.d->size = d->qt_rgn->numRects;
         return d->qt_rgn->rects;
     } else {
         return QVector<QRect>();
-- 
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