1berry/qtbase
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

QJsonValueConstRef: prepare for Qt 7

Browse Source 
Instead of storing a pointer to the QJsonArray or QJsonObject (like the
Qt 4 & pre-5.15 versions did), do like QCborValueConstRef and store the
pointer to the QCborContainerPrivate.

Unlike QCborValueRef, we must keep the is_object bit because of API
behavior that assigning an Undefined to an object reference deletes it
from the container. I've chosen to use size_t instead of qsizetype for
this because then we don't lose any bits of the index. Therefore, the
index in the case of objects is stored as pair count (like before),
different from QCborValueRef which stores the actual index in the
QCborContainerPrivate.

It's the LSB (on little-endian architectures) so the calculation of
2 * index + 1 is the actual value stored in memory or in the
register. Unfortunately, right now, both Clang and GCC don't realize
this and generate unnecessary instructions. Clang:

0000000000000000 <QJsonValueConstRef::concreteType(QJsonValueConstRef)>:
   0:   mov    %rsi,%rax
   3:   shr    %rax
   6:   mov    %rsi,%rcx
   9:   or     $0x1,%rcx
   d:   test   $0x1,%sil
  11:   cmove  %rax,%rcx

[GCC code is identical, except it uses an AND instead of TEST]

That OR at offset 9 is a no-op because it sets a bit that is already set
in those conditions. At least they don't do unnecessary shifts.

Change-Id: I89446ea06b5742efb194fffd16bb7aadb6a9b341
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
This commit is contained in:
Thiago Macieira 2021-11-27 10:29:35 -08:00
parent a747ab0b72
commit 705ea62f9e
6 changed files with 110 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/corelib/serialization/qjson_p.h
View File

@ -56,8 +56,10 @@
#include <qcborvalue.h>
#include <private/qcborvalue_p.h>
#include <qjsonarray.h>
#include <qjsonobject.h>
#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0) && !defined(QT_BOOTSTRAPPED)
# include <qjsonarray.h>
# include <qjsonobject.h>
#endif
QT_BEGIN_NAMESPACE
@ -209,7 +211,11 @@ public:
static QCborContainerPrivate *container(const QCborValue &v) { return v.container; }
static const QCborContainerPrivate *container(QJsonValueConstRef r) noexcept
{
#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0) && !defined(QT_BOOTSTRAPPED)
return (r.is_object ? r.o->o : r.a->a).data();
#else
return r.d;
#endif
}
static QCborContainerPrivate *container(QJsonValueRef r) noexcept
{

30
src/corelib/serialization/qjsonarray.h
View File

@ -120,8 +120,7 @@ public:
constexpr iterator(const iterator &other) = default;
iterator &operator=(const iterator &other)
{
item.a = other.item.a;
item.index = other.item.index;
item.rebind(other.item);
return *this;
}
@ -131,21 +130,21 @@ public:
inline QJsonValueRef operator[](qsizetype j) const { return *(*this + j); }
inline bool operator==(const iterator &o) const
{ return item.a == o.item.a && item.index == o.item.index; }
{ return item.d == o.item.d && item.index == o.item.index; }
inline bool operator!=(const iterator &o) const { return !(*this == o); }
inline bool operator<(const iterator &other) const
{ Q_ASSERT(item.a == other.item.a); return item.index < other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
inline bool operator<=(const iterator &other) const
{ Q_ASSERT(item.a == other.item.a); return item.index <= other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
inline bool operator>(const iterator &other) const { return !(*this <= other); }
inline bool operator>=(const iterator &other) const { return !(*this < other); }
inline bool operator==(const const_iterator &o) const
{ return item.a == o.item.a && item.index == o.item.index; }
{ return item.d == o.item.d && item.index == o.item.index; }
inline bool operator!=(const const_iterator &o) const { return !(*this == o); }
inline bool operator<(const const_iterator &other) const
{ Q_ASSERT(item.a == other.item.a); return item.index < other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
inline bool operator<=(const const_iterator &other) const
{ Q_ASSERT(item.a == other.item.a); return item.index <= other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
inline bool operator>(const const_iterator &other) const { return !(*this <= other); }
inline bool operator>=(const const_iterator &other) const { return !(*this < other); }
inline iterator &operator++() { ++item.index; return *this; }
@ -180,8 +179,7 @@ public:
constexpr const_iterator(const const_iterator &other) = default;
const_iterator &operator=(const const_iterator &other)
{
item.a = other.item.a;
item.index = other.item.index;
item.rebind(other.item);
return *this;
}
@ -190,12 +188,12 @@ public:
inline QJsonValueConstRef operator[](qsizetype j) const { return *(*this + j); }
inline bool operator==(const const_iterator &o) const
{ return item.a == o.item.a && item.index == o.item.index; }
{ return item.d == o.item.d && item.index == o.item.index; }
inline bool operator!=(const const_iterator &o) const { return !(*this == o); }
inline bool operator<(const const_iterator &other) const
{ Q_ASSERT(item.a == other.item.a); return item.index < other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
inline bool operator<=(const const_iterator &other) const
{ Q_ASSERT(item.a == other.item.a); return item.index <= other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
inline bool operator>(const const_iterator &other) const { return !(*this <= other); }
inline bool operator>=(const const_iterator &other) const { return !(*this < other); }
inline const_iterator &operator++() { ++item.index; return *this; }
@ -271,6 +269,12 @@ private:
Q_DECLARE_SHARED(QJsonArray)
#if QT_VERSION >= QT_VERSION_CHECK(7, 0, 0) || defined(QT_BOOTSTRAPPED)
inline QJsonValueConstRef::QJsonValueConstRef(QJsonArray *a, qsizetype idx)
: d(a->a.data()), is_object(false), index(idx)
{}
#endif
Q_CORE_EXPORT size_t qHash(const QJsonArray &array, size_t seed = 0);
#if !defined(QT_NO_DEBUG_STREAM) && !defined(QT_JSON_READONLY)

2
src/corelib/serialization/qjsonobject.cpp
View File

@ -1419,6 +1419,7 @@ bool QJsonObject::detach(qsizetype reserve)
return o;
}
#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0) && !defined(QT_BOOTSTRAPPED)
/*!
\internal
*/
@ -1428,7 +1429,6 @@ QString QJsonObject::keyAt(qsizetype i) const
return o->stringAt(i * 2);
}
#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0) && !defined(QT_BOOTSTRAPPED)
/*!
\internal
*/

42
src/corelib/serialization/qjsonobject.h
View File

@ -136,12 +136,11 @@ public:
constexpr iterator(const iterator &other) = default;
iterator &operator=(const iterator &other)
{
item.o = other.item.o;
item.index = other.item.index;
item.rebind(other.item);
return *this;
}
inline QString key() const { return item.o->keyAt(item.index); }
inline QString key() const { return item.objectKey(); }
inline QJsonValueRef value() const { return item; }
inline QJsonValueRef operator*() const { return item; }
inline const QJsonValueConstRef *operator->() const { return &item; }
@ -149,12 +148,12 @@ public:
inline QJsonValueRef operator[](qsizetype j) const { return *(*this + j); }
inline bool operator==(const iterator &other) const
{ return item.o == other.item.o && item.index == other.item.index; }
{ return item.d == other.item.d && item.index == other.item.index; }
inline bool operator!=(const iterator &other) const { return !(*this == other); }
bool operator<(const iterator& other) const
{ Q_ASSERT(item.o == other.item.o); return item.index < other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
bool operator<=(const iterator& other) const
{ Q_ASSERT(item.o == other.item.o); return item.index <= other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
bool operator>(const iterator& other) const { return !(*this <= other); }
bool operator>=(const iterator& other) const { return !(*this < other); }
@ -170,12 +169,12 @@ public:
public:
inline bool operator==(const const_iterator &other) const
{ return item.o == other.item.o && item.index == other.item.index; }
{ return item.d == other.item.d && item.index == other.item.index; }
inline bool operator!=(const const_iterator &other) const { return !(*this == other); }
bool operator<(const const_iterator& other) const
{ Q_ASSERT(item.o == other.item.o); return item.index < other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
bool operator<=(const const_iterator& other) const
{ Q_ASSERT(item.o == other.item.o); return item.index <= other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
bool operator>(const const_iterator& other) const { return !(*this <= other); }
bool operator>=(const const_iterator& other) const { return !(*this < other); }
};
@ -202,24 +201,23 @@ public:
constexpr const_iterator(const const_iterator &other) = default;
const_iterator &operator=(const const_iterator &other)
{
item.o = other.item.o;
item.index = other.item.index;
item.rebind(other.item);
return *this;
}
inline QString key() const { return item.o->keyAt(item.index); }
inline QString key() const { return item.objectKey(); }
inline QJsonValueConstRef value() const { return item; }
inline const QJsonValueConstRef operator*() const { return item; }
inline const QJsonValueConstRef *operator->() const { return &item; }
inline QJsonValueConstRef operator[](qsizetype j) const { return *(*this + j); }
inline bool operator==(const const_iterator &other) const
{ return item.o == other.item.o && item.index == other.item.index; }
{ return item.d == other.item.d && item.index == other.item.index; }
inline bool operator!=(const const_iterator &other) const { return !(*this == other); }
bool operator<(const const_iterator& other) const
{ Q_ASSERT(item.o == other.item.o); return item.index < other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
bool operator<=(const const_iterator& other) const
{ Q_ASSERT(item.o == other.item.o); return item.index <= other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
bool operator>(const const_iterator& other) const { return !(*this <= other); }
bool operator>=(const const_iterator& other) const { return !(*this < other); }
@ -234,12 +232,12 @@ public:
qsizetype operator-(const_iterator j) const { return item.index - j.item.index; }
inline bool operator==(const iterator &other) const
{ return item.o == other.item.o && item.index == other.item.index; }
{ return item.d == other.item.d && item.index == other.item.index; }
inline bool operator!=(const iterator &other) const { return !(*this == other); }
bool operator<(const iterator& other) const
{ Q_ASSERT(item.o == other.item.o); return item.index < other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
bool operator<=(const iterator& other) const
{ Q_ASSERT(item.o == other.item.o); return item.index <= other.item.index; }
{ Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
bool operator>(const iterator& other) const { return !(*this <= other); }
bool operator>=(const iterator& other) const { return !(*this < other); }
};
@ -300,8 +298,8 @@ private:
template <typename T> const_iterator constFindImpl(T key) const;
template <typename T> iterator insertImpl(T key, const QJsonValue &value);
QString keyAt(qsizetype i) const;
#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0) && !defined(QT_BOOTSTRAPPED)
QString keyAt(qsizetype i) const;
QJsonValue valueAt(qsizetype i) const;
void setValueAt(qsizetype i, const QJsonValue &val);
#endif
@ -313,6 +311,12 @@ private:
Q_DECLARE_SHARED(QJsonObject)
#if QT_VERSION >= QT_VERSION_CHECK(7, 0, 0) || defined(QT_BOOTSTRAPPED)
inline QJsonValueConstRef::QJsonValueConstRef(QJsonObject *o, qsizetype idx)
: d(o->o.data()), is_object(true), index(idx)
{}
#endif
Q_CORE_EXPORT size_t qHash(const QJsonObject &object, size_t seed = 0);
#if !defined(QT_NO_DEBUG_STREAM) && !defined(QT_JSON_READONLY)

16
src/corelib/serialization/qjsonvalue.cpp
View File

@ -921,6 +921,7 @@ bool QJsonValue::operator!=(const QJsonValue &other) const
void QJsonValueRef::detach()
{
#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0) && !defined(QT_BOOTSTRAPPED)
QCborContainerPrivate *d = QJsonPrivate::Value::container(*this);
d = QCborContainerPrivate::detach(d, d->elements.size());
@ -928,6 +929,9 @@ void QJsonValueRef::detach()
o->o.reset(d);
else
a->a.reset(d);
#else
d = QCborContainerPrivate::detach(d, d->elements.size());
#endif
}
static QJsonValueRef &assignToRef(QJsonValueRef &ref, const QCborValue &value, bool is_object)
@ -1036,6 +1040,18 @@ QJsonValue QJsonValueConstRef::concrete(QJsonValueConstRef self) noexcept
return QJsonPrivate::Value::fromTrustedCbor(d->valueAt(index));
}
QString QJsonValueConstRef::objectKey(QJsonValueConstRef self)
{
Q_ASSERT(self.is_object);
Q_ASSUME(self.is_object);
const QCborContainerPrivate *d = QJsonPrivate::Value::container(self);
qsizetype index = QJsonPrivate::Value::indexHelper(self);
Q_ASSERT(d);
Q_ASSERT(index < d->elements.size());
return d->stringAt(index - 1);
}
#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0) && !defined(QT_BOOTSTRAPPED)
QVariant QJsonValueRef::toVariant() const
{

55
src/corelib/serialization/qjsonvalue.h
View File

@ -190,11 +190,6 @@ public:
inline bool operator!=(const QJsonValue &other) const { return concrete(*this) != other; }
protected:
QJsonValueConstRef(QJsonArray *array, qsizetype idx)
: a(array), is_object(false), index(static_cast<quint64>(idx)) {}
QJsonValueConstRef(QJsonObject *object, qsizetype idx)
: o(object), is_object(true), index(static_cast<quint64>(idx)) {}
Q_CORE_EXPORT static QJsonValue::Type
concreteType(QJsonValueConstRef self) noexcept Q_DECL_PURE_FUNCTION;
Q_CORE_EXPORT static bool
@ -206,12 +201,48 @@ protected:
Q_CORE_EXPORT static QString concreteString(QJsonValueConstRef self, const QString &defaultValue);
Q_CORE_EXPORT static QJsonValue concrete(QJsonValueConstRef self) noexcept;
// for iterators
Q_CORE_EXPORT static QString objectKey(QJsonValueConstRef self);
QString objectKey() const { return objectKey(*this); }
#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0) && !defined(QT_BOOTSTRAPPED)
QJsonValueConstRef(QJsonArray *array, qsizetype idx)
: a(array), is_object(false), index(static_cast<quint64>(idx)) {}
QJsonValueConstRef(QJsonObject *object, qsizetype idx)
: o(object), is_object(true), index(static_cast<quint64>(idx)) {}
void rebind(QJsonValueConstRef other)
{
Q_ASSERT(is_object == other.is_object);
if (is_object)
o = other.o;
else
a = other.a;
index = other.index;
}
union {
QJsonArray *a;
QJsonObject *o;
void *d;
};
quint64 is_object : 1;
quint64 index : 63;
#else
// implemented in qjsonarray.h & qjsonobject.h, to get their d
QJsonValueConstRef(QJsonArray *array, qsizetype idx);
QJsonValueConstRef(QJsonObject *object, qsizetype idx);
void rebind(QJsonValueConstRef other)
{
d = other.d;
index = other.index;
}
QCborContainerPrivate *d = nullptr;
size_t is_object : 1;
size_t index : std::numeric_limits<size_t>::digits - 1;
#endif
friend class QJsonArray;
friend class QJsonObject;
@ -221,11 +252,6 @@ protected:
class Q_CORE_EXPORT QJsonValueRef : public QJsonValueConstRef
{
public:
QJsonValueRef(QJsonArray *array, qsizetype idx)
: QJsonValueConstRef(array, idx) {}
QJsonValueRef(QJsonObject *object, qsizetype idx)
: QJsonValueConstRef(object, idx) {}
QJsonValueRef(const QJsonValueRef &) = default;
QJsonValueRef &operator = (const QJsonValue &val);
QJsonValueRef &operator = (const QJsonValueRef &val);
@ -234,6 +260,11 @@ public:
// retained for binary compatibility (due to the Q_CORE_EXPORT) because at
// least one compiler emits and exports all inlines in an exported class
QJsonValueRef(QJsonArray *array, qsizetype idx)
: QJsonValueConstRef(array, idx) {}
QJsonValueRef(QJsonObject *object, qsizetype idx)
: QJsonValueConstRef(object, idx) {}
operator QJsonValue() const { return toValue(); }
QVariant toVariant() const;
@ -265,8 +296,12 @@ private:
QJsonValue toValue() const;
#else
private:
using QJsonValueConstRef::QJsonValueConstRef;
#endif // < Qt 7
void detach();
friend class QJsonArray;
friend class QJsonObject;
};
inline QJsonValue QCborValueConstRef::toJsonValue() const