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Endian: Remove old special integer bitfields 

The only way to use them was to put them in a union and then write all
the members of the union to set the various bit ranges. As only one
member of a union can be active at any time, the compiler is free to
optimize those writes away, though. This has started happening in the
wild now.

As we have a replacement, we can remove the old and broken code now.

Task-number: QTBUG-99545
Change-Id: I90718ec06662258d1c15220f54da9eed2186c5a5
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
bb10
Ulf Hermann 2022-05-05 16:21:46 +02:00
parent bc144312c1
commit 4912903e37
2 changed files with 0 additions and 104 deletions
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75
src/corelib/global/qendian_p.h
View File

@ -20,81 +20,6 @@
QT_BEGIN_NAMESPACE
// Note if using multiple of these bitfields in a union; the underlying storage type must
// match. Since we always use an unsigned storage type, unsigned and signed versions may
// be used together, but different bit-widths may not.
template<class S, int pos, int width>
class QSpecialIntegerBitfield
{
protected:
typedef typename S::StorageType T;
typedef typename std::make_unsigned<T>::type UT;
static constexpr UT mask()
{
return ((UT(1) << width) - 1) << pos;
}
public:
// FIXME: val is public until qtdeclarative is fixed to not access it directly.
UT val;
QSpecialIntegerBitfield &operator=(T t)
{
UT i = S::fromSpecial(val);
i &= ~mask();
i |= (UT(t) << pos) & mask();
val = S::toSpecial(i);
return *this;
}
operator T() const
{
if (std::is_signed<T>::value) {
UT i = S::fromSpecial(val);
i <<= (sizeof(T) * 8) - width - pos;
T t = T(i);
t >>= (sizeof(T) * 8) - width;
return t;
}
return (S::fromSpecial(val) & mask()) >> pos;
}
bool operator!() const { return !(val & S::toSpecial(mask())); }
bool operator==(QSpecialIntegerBitfield<S, pos, width> i) const
{
return ((val ^ i.val) & S::toSpecial(mask())) == 0;
}
bool operator!=(QSpecialIntegerBitfield<S, pos, width> i) const
{
return ((val ^ i.val) & S::toSpecial(mask())) != 0;
}
QSpecialIntegerBitfield &operator+=(T i) { return (*this = (T(*this) + i)); }
QSpecialIntegerBitfield &operator-=(T i) { return (*this = (T(*this) - i)); }
QSpecialIntegerBitfield &operator*=(T i) { return (*this = (T(*this) * i)); }
QSpecialIntegerBitfield &operator/=(T i) { return (*this = (T(*this) / i)); }
QSpecialIntegerBitfield &operator%=(T i) { return (*this = (T(*this) % i)); }
QSpecialIntegerBitfield &operator|=(T i) { return (*this = (T(*this) | i)); }
QSpecialIntegerBitfield &operator&=(T i) { return (*this = (T(*this) & i)); }
QSpecialIntegerBitfield &operator^=(T i) { return (*this = (T(*this) ^ i)); }
QSpecialIntegerBitfield &operator>>=(T i) { return (*this = (T(*this) >> i)); }
QSpecialIntegerBitfield &operator<<=(T i) { return (*this = (T(*this) << i)); }
};
template<typename T, int pos, int width>
using QLEIntegerBitfield = QSpecialIntegerBitfield<QLittleEndianStorageType<T>, pos, width>;
template<typename T, int pos, int width>
using QBEIntegerBitfield = QSpecialIntegerBitfield<QBigEndianStorageType<T>, pos, width>;
template<int pos, int width>
using qint32_le_bitfield = QLEIntegerBitfield<int, pos, width>;
template<int pos, int width>
using quint32_le_bitfield = QLEIntegerBitfield<uint, pos, width>;
template<int pos, int width>
using qint32_be_bitfield = QBEIntegerBitfield<int, pos, width>;
template<int pos, int width>
using quint32_be_bitfield = QBEIntegerBitfield<uint, pos, width>;
enum class QSpecialIntegerBitfieldInitializer {};
constexpr QSpecialIntegerBitfieldInitializer QSpecialIntegerBitfieldZero{};

29
tests/auto/corelib/global/qtendian/tst_qtendian.cpp
View File

@ -35,8 +35,6 @@ private slots:
void endianIntegers_data();
void endianIntegers();
void endianBitfields();
void endianBitfieldUnions_data();
void endianBitfieldUnions();
};
@ -344,33 +342,6 @@ void tst_QtEndian::endianIntegers()
#endif
}
void tst_QtEndian::endianBitfields()
{
union {
quint32_be_bitfield<21, 11> upper;
quint32_be_bitfield<10, 11> lower;
qint32_be_bitfield<0, 10> bottom;
} u;
u.upper = 200;
QCOMPARE(u.upper, 200U);
u.lower = 1000;
u.bottom = -8;
QCOMPARE(u.lower, 1000U);
QCOMPARE(u.upper, 200U);
u.lower += u.upper;
QCOMPARE(u.upper, 200U);
QCOMPARE(u.lower, 1200U);
u.upper = 65536 + 7;
u.lower = 65535;
QCOMPARE(u.lower, 65535U & ((1<<11) - 1));
QCOMPARE(u.upper, 7U);
QCOMPARE(u.bottom, -8);
}
template<template<typename... Accessors> typename Union, template<int, int, typename> typename Member>
void testBitfieldUnion()
{