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Get rid of QArrayData::sharedNull() 

Remove the last places where those got used and avoid
allocations when we resize to 0.

Change-Id: Ib553f4e7ce7cc24c31da15a55a86d18bdf1cc5c3
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
bb10
Lars Knoll 2019-12-03 12:21:46 +01:00
parent c01804bd1e
commit fbce2e58e6
8 changed files with 22 additions and 123 deletions
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4
src/corelib/text/qbytearray.cpp
View File

@ -1732,7 +1732,7 @@ QByteArray QByteArray::nulTerminated() const
QByteArray &QByteArray::prepend(const QByteArray &ba)
{
if (size() == 0 && d->isStatic() && ba.d.isMutable()) {
if (size() == 0 && ba.d.isMutable()) {
*this = ba;
} else if (ba.size() != 0) {
QByteArray tmp = *this;
@ -1825,7 +1825,7 @@ QByteArray &QByteArray::prepend(char ch)
QByteArray &QByteArray::append(const QByteArray &ba)
{
if (size() == 0 && d->isStatic() && ba.d.isMutable()) {
if (size() == 0 && ba.d.isMutable()) {
*this = ba;
} else if (ba.size() != 0) {
if (d->needsDetach() || size() + ba.size() > capacity())

25
src/corelib/tools/qarraydata.cpp
View File

@ -147,25 +147,7 @@ qCalculateGrowingBlockSize(size_t elementCount, size_t elementSize, size_t heade
return result;
}
// End of qtools_p.h implementation
QT_WARNING_PUSH
QT_WARNING_DISABLE_GCC("-Wmissing-field-initializers")
const QArrayData QArrayData::shared_null[2] = {
{ Q_BASIC_ATOMIC_INITIALIZER(-1), 0, 0 }, // shared null
/* zero initialized terminator */};
static const QArrayData emptyNotNullShared[2] = {
{ Q_BASIC_ATOMIC_INITIALIZER(-1), 0, 0 }, // shared empty
/* zero initialized terminator */};
QT_WARNING_POP
static const QArrayData &qt_array_empty = emptyNotNullShared[0];
static inline size_t calculateBlockSize(size_t &capacity, size_t objectSize, size_t headerSize,
uint options)
static inline size_t calculateBlockSize(size_t &capacity, size_t objectSize, size_t headerSize, uint options)
{
// Calculate the byte size
// allocSize = objectSize * capacity + headerSize, but checked for overflow
@ -199,9 +181,8 @@ void *QArrayData::allocate(QArrayData **dptr, size_t objectSize, size_t alignmen
&& !(alignment & (alignment - 1)));
if (capacity == 0) {
// optimization for empty headers
*dptr = const_cast<QArrayData *>(&qt_array_empty);
return sharedNullData();
*dptr = nullptr;
return nullptr;
}
size_t headerSize = sizeof(QArrayData);

18
src/corelib/tools/qarraydata.h
View File

@ -77,24 +77,16 @@ struct Q_CORE_EXPORT QArrayData
/// Returns true if sharing took place
bool ref()
{
if (!isStatic())
ref_.ref();
ref_.ref();
return true;
}
/// Returns false if deallocation is necessary
bool deref()
{
if (isStatic())
return true;
return ref_.deref();
}
bool isStatic() const
{
return ref_.loadRelaxed() == -1;
}
bool isShared() const
{
return ref_.loadRelaxed() != 1;
@ -133,14 +125,6 @@ struct Q_CORE_EXPORT QArrayData
size_t objectSize, size_t newCapacity, ArrayOptions newOptions = DefaultAllocationFlags) Q_DECL_NOTHROW;
static void deallocate(QArrayData *data, size_t objectSize,
size_t alignment) noexcept;
static const QArrayData shared_null[2];
static QArrayData *sharedNull() noexcept { return const_cast<QArrayData*>(shared_null); }
static void *sharedNullData()
{
QArrayData *const null = const_cast<QArrayData *>(&shared_null[1]);
return null;
}
};
Q_DECLARE_OPERATORS_FOR_FLAGS(QArrayData::ArrayOptions)

3
src/corelib/tools/qarraydatapointer.h
View File

@ -78,7 +78,6 @@ public:
explicit QArrayDataPointer(QPair<QTypedArrayData<T> *, T *> adata, size_t n = 0)
: d(adata.first), ptr(adata.second), size(int(n))
{
Q_CHECK_PTR(d);
}
static QArrayDataPointer fromRawData(const T *rawData, size_t length)
@ -183,7 +182,6 @@ public:
void ref() noexcept { if (d) d->ref(); }
bool deref() noexcept { return !d || d->deref(); }
bool isMutable() const noexcept { return d; }
bool isStatic() const noexcept { return !d; }
bool isShared() const noexcept { return !d || d->isShared(); }
bool isSharedWith(const QArrayDataPointer &other) const noexcept { return d && d == other.d; }
bool needsDetach() const noexcept { return !d || d->needsDetach(); }
@ -199,7 +197,6 @@ private:
Q_REQUIRED_RESULT QPair<Data *, T *> clone(QArrayData::ArrayOptions options) const
{
QPair<Data *, T *> pair = Data::allocate(detachCapacity(size), options);
Q_CHECK_PTR(pair.first);
QArrayDataPointer copy(pair.first, pair.second, 0);
if (size)
copy->copyAppend(begin(), end());

4
tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
View File

@ -167,8 +167,8 @@ QByteArray verifyZeroTermination(const QByteArray &ba)
QByteArray::DataPointer baDataPtr = const_cast<QByteArray &>(ba).data_ptr();
// Skip if isStatic() as those offer no guarantees
if (baDataPtr->isStatic())
// Skip if !isMutable() as those offer no guarantees
if (!baDataPtr->isMutable())
return ba;
int baSize = ba.size();

2
tests/auto/corelib/text/qstring/tst_qstring.cpp
View File

@ -618,7 +618,7 @@ QString verifyZeroTermination(const QString &str)
QString::DataPointer strDataPtr = const_cast<QString &>(str).data_ptr();
// Skip if isStatic() or fromRawData(), as those offer no guarantees
if (strDataPtr->isStatic() || !strDataPtr->isMutable())
if (!strDataPtr->isMutable())
return str;
int strSize = str.size();

2
tests/auto/corelib/tools/qarraydata/simplevector.h
View File

@ -85,7 +85,7 @@ public:
bool isNull() const { return d.isNull(); }
bool isEmpty() const { return this->empty(); }
bool isStatic() const { return d->isStatic(); }
bool isStatic() const { return !d.isMutable(); }
bool isShared() const { return d->isShared(); }
bool isSharedWith(const SimpleVector &other) const { return d == other.d; }

87
tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp
View File

@ -33,29 +33,12 @@
#include "simplevector.h"
struct SharedNullVerifier
{
SharedNullVerifier()
{
Q_ASSERT(QArrayData::shared_null[0].isStatic());
Q_ASSERT(QArrayData::shared_null[0].isShared());
}
};
// This is meant to verify/ensure that shared_null is not being dynamically
// initialized and stays away from the order-of-static-initialization fiasco.
//
// Of course, if this was to fail, qmake and the build should have crashed and
// burned before we ever got to this point :-)
SharedNullVerifier globalInit;
class tst_QArrayData : public QObject
{
Q_OBJECT
private slots:
void referenceCounting();
void sharedNullEmpty();
void simpleVector();
void simpleVectorReserve_data();
void simpleVectorReserve();
@ -87,8 +70,6 @@ void tst_QArrayData::referenceCounting()
QCOMPARE(array.ref_.loadRelaxed(), 1);
QVERIFY(!array.isStatic());
QVERIFY(array.ref());
QCOMPARE(array.ref_.loadRelaxed(), 2);
@ -108,37 +89,6 @@ void tst_QArrayData::referenceCounting()
}
}
void tst_QArrayData::sharedNullEmpty()
{
QArrayData *null = const_cast<QArrayData *>(QArrayData::shared_null);
QArrayData *empty;
QArrayData::allocate(&empty, 1, alignof(QArrayData), 0);
QVERIFY(null->isStatic());
QVERIFY(null->isShared());
QVERIFY(empty->isStatic());
QVERIFY(empty->isShared());
QCOMPARE(null->ref_.loadRelaxed(), -1);
QCOMPARE(empty->ref_.loadRelaxed(), -1);
QCOMPARE(null->ref_.loadRelaxed(), -1);
QCOMPARE(empty->ref_.loadRelaxed(), -1);
QVERIFY(null->deref());
QVERIFY(empty->deref());
QCOMPARE(null->ref_.loadRelaxed(), -1);
QCOMPARE(empty->ref_.loadRelaxed(), -1);
QVERIFY(null != empty);
QCOMPARE(null->allocatedCapacity(), size_t(0));
QCOMPARE(empty->allocatedCapacity(), size_t(0));
}
void tst_QArrayData::simpleVector()
{
int data[] = { 0, 1, 2, 3, 4, 5, 6 };
@ -479,7 +429,6 @@ void tst_QArrayData::allocate_data()
QTest::addColumn<size_t>("alignment");
QTest::addColumn<QArrayData::ArrayOptions>("allocateOptions");
QTest::addColumn<bool>("isCapacityReserved");
QTest::addColumn<const QArrayData *>("commonEmpty");
struct {
char const *typeName;
@ -491,19 +440,14 @@ void tst_QArrayData::allocate_data()
{ "void *", sizeof(void *), alignof(void *) }
};
QArrayData *shared_empty;
(void)QArrayData::allocate(&shared_empty, 1, alignof(QArrayData), 0);
QVERIFY(shared_empty);
struct {
char const *description;
QArrayData::ArrayOptions allocateOptions;
bool isCapacityReserved;
const QArrayData *commonEmpty;
} options[] = {
{ "Default", QArrayData::DefaultAllocationFlags, false, shared_empty },
{ "Reserved", QArrayData::CapacityReserved, true, shared_empty },
{ "Grow", QArrayData::GrowsForward, false, shared_empty }
{ "Default", QArrayData::DefaultAllocationFlags, false },
{ "Reserved", QArrayData::CapacityReserved, true },
{ "Grow", QArrayData::GrowsForward, false }
};
for (size_t i = 0; i < sizeof(types)/sizeof(types[0]); ++i)
@ -513,8 +457,7 @@ void tst_QArrayData::allocate_data()
+ QLatin1String(": ")
+ QLatin1String(options[j].description)))
<< types[i].objectSize << types[i].alignment
<< options[j].allocateOptions << options[j].isCapacityReserved
<< options[j].commonEmpty;
<< options[j].allocateOptions << options[j].isCapacityReserved;
}
void tst_QArrayData::allocate()
@ -523,21 +466,15 @@ void tst_QArrayData::allocate()
QFETCH(size_t, alignment);
QFETCH(QArrayData::ArrayOptions, allocateOptions);
QFETCH(bool, isCapacityReserved);
QFETCH(const QArrayData *, commonEmpty);
// Minimum alignment that can be requested is that of QArrayData.
// Typically, this alignment is sizeof(void *) and ensured by malloc.
size_t minAlignment = qMax(alignment, alignof(QArrayData));
// Shared Empty
QArrayData *empty;
QCOMPARE((QArrayData::allocate(&empty, objectSize, minAlignment, 0,
QArrayData::ArrayOptions(allocateOptions)), empty), commonEmpty);
Deallocator keeper(objectSize, minAlignment);
keeper.headers.reserve(1024);
for (int capacity = 1; capacity <= 1024; capacity <<= 1) {
for (qsizetype capacity = 1; capacity <= 1024; capacity <<= 1) {
QArrayData *data;
void *dataPointer = QArrayData::allocate(&data, objectSize, minAlignment,
capacity, QArrayData::ArrayOptions(allocateOptions));
@ -545,9 +482,9 @@ void tst_QArrayData::allocate()
keeper.headers.append(data);
if (allocateOptions & QArrayData::GrowsForward)
QVERIFY(data->allocatedCapacity() > uint(capacity));
QVERIFY(data->allocatedCapacity() > capacity);
else
QCOMPARE(data->allocatedCapacity(), size_t(capacity));
QCOMPARE(data->allocatedCapacity(), capacity);
QCOMPARE(bool(data->flags & QArrayData::CapacityReserved), isCapacityReserved);
// Check that the allocated array can be used. Best tested with a
@ -587,9 +524,9 @@ void tst_QArrayData::reallocate()
keeper.headers.append(data);
if (allocateOptions & QArrayData::GrowsForward)
QVERIFY(data->allocatedCapacity() > size_t(newCapacity));
QVERIFY(data->allocatedCapacity() > newCapacity);
else
QCOMPARE(data->allocatedCapacity(), size_t(newCapacity));
QCOMPARE(data->allocatedCapacity(), newCapacity);
QCOMPARE(!(data->flags & QArrayData::CapacityReserved), !isCapacityReserved);
for (int i = 0; i < capacity; ++i)
@ -658,7 +595,7 @@ void tst_QArrayData::typedData()
keeper.headers.append(array);
QVERIFY(array);
QCOMPARE(array->allocatedCapacity(), size_t(10));
QCOMPARE(array->allocatedCapacity(), qsizetype(10));
// Check that the allocated array can be used. Best tested with a
// memory checker, such as valgrind, running.
@ -678,7 +615,7 @@ void tst_QArrayData::typedData()
keeper.headers.append(array);
QVERIFY(array);
QCOMPARE(array->allocatedCapacity(), size_t(10));
QCOMPARE(array->allocatedCapacity(), qsizetype(10));
// Check that the allocated array can be used. Best tested with a
// memory checker, such as valgrind, running.
@ -698,7 +635,7 @@ void tst_QArrayData::typedData()
keeper.headers.append(array);
QVERIFY(array);
QCOMPARE(array->allocatedCapacity(), size_t(10));
QCOMPARE(array->allocatedCapacity(), qsizetype(10));
// Check that the allocated array can be used. Best tested with a
// memory checker, such as valgrind, running.