summaryrefslogtreecommitdiffstats
path: root/src
diff options
context:
space:
mode:
authorLars Knoll <lars.knoll@qt.io>2020-02-05 14:47:26 +0100
committerLars Knoll <lars.knoll@qt.io>2020-03-14 10:36:37 +0100
commitf75160774abfcdfc2fb17f382fe2a6b28ba181a5 (patch)
tree883ab6547d05734f3a1bee526b9e837c1950cbd6 /src
parenta02ec931b6c40ce27609772742db34e8963e42a6 (diff)
Cleanup code in QContiguousCache
Remove the union being used to hold the d-pointer, as accessing both members of the union on the same data is technically undefined behavior. Change-Id: Ia5a063d97538222575a47e9462c0675acdf32aef Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'src')
-rw-r--r--src/corelib/tools/qcontiguouscache.h168
1 files changed, 74 insertions, 94 deletions
diff --git a/src/corelib/tools/qcontiguouscache.h b/src/corelib/tools/qcontiguouscache.h
index 451ba3e8de..fb487b60a1 100644
--- a/src/corelib/tools/qcontiguouscache.h
+++ b/src/corelib/tools/qcontiguouscache.h
@@ -57,11 +57,6 @@ struct Q_CORE_EXPORT QContiguousCacheData
int start;
int offset;
- // total is 24 bytes (HP-UX aCC: 40 bytes)
- // the next entry is already aligned to 8 bytes
- // there will be an 8 byte gap here if T requires 16-byte alignment
- // (such as long double on 64-bit platforms, __int128, __float128)
-
static QContiguousCacheData *allocateData(int size, int alignment);
static void freeData(QContiguousCacheData *data);
@@ -71,18 +66,15 @@ struct Q_CORE_EXPORT QContiguousCacheData
};
template <typename T>
-struct QContiguousCacheTypedData: private QContiguousCacheData
+struct QContiguousCacheTypedData : public QContiguousCacheData
{
- // private inheritance to avoid aliasing warningss
T array[1];
-
- static inline void freeData(QContiguousCacheTypedData *data) { QContiguousCacheData::freeData(data); }
};
template<typename T>
class QContiguousCache {
typedef QContiguousCacheTypedData<T> Data;
- union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; };
+ Data *d;
public:
// STL compatibility
typedef T value_type;
@@ -96,7 +88,7 @@ public:
explicit QContiguousCache(int capacity = 0);
QContiguousCache(const QContiguousCache<T> &v) : d(v.d) { d->ref.ref(); }
- inline ~QContiguousCache() { if (!d) return; if (!d->ref.deref()) freeData(p); }
+ inline ~QContiguousCache() { if (!d) return; if (!d->ref.deref()) freeData(d); }
inline void detach() { if (d->ref.loadRelaxed() != 1) detach_helper(); }
inline bool isDetached() const { return d->ref.loadRelaxed() == 1; }
@@ -131,10 +123,10 @@ public:
inline int firstIndex() const { return d->offset; }
inline int lastIndex() const { return d->offset + d->count - 1; }
- inline const T &first() const { Q_ASSERT(!isEmpty()); return p->array[d->start]; }
- inline const T &last() const { Q_ASSERT(!isEmpty()); return p->array[(d->start + d->count -1) % d->alloc]; }
- inline T &first() { Q_ASSERT(!isEmpty()); detach(); return p->array[d->start]; }
- inline T &last() { Q_ASSERT(!isEmpty()); detach(); return p->array[(d->start + d->count -1) % d->alloc]; }
+ inline const T &first() const { Q_ASSERT(!isEmpty()); return d->array[d->start]; }
+ inline const T &last() const { Q_ASSERT(!isEmpty()); return d->array[(d->start + d->count -1) % d->alloc]; }
+ inline T &first() { Q_ASSERT(!isEmpty()); detach(); return d->array[d->start]; }
+ inline T &last() { Q_ASSERT(!isEmpty()); detach(); return d->array[(d->start + d->count -1) % d->alloc]; }
void removeFirst();
T takeFirst();
@@ -147,39 +139,28 @@ public:
inline void normalizeIndexes() { d->offset = d->start; }
#ifdef QT_QCONTIGUOUSCACHE_DEBUG
- void dump() const { p->dump(); }
+ void dump() const { d->dump(); }
#endif
private:
void detach_helper();
- QContiguousCacheData *allocateData(int aalloc);
+ Data *allocateData(int aalloc);
void freeData(Data *x);
- int sizeOfTypedData() {
- // this is more or less the same as sizeof(Data), except that it doesn't
- // count the padding at the end
- return reinterpret_cast<const char *>(&(reinterpret_cast<const Data *>(this))->array[1]) - reinterpret_cast<const char *>(this);
- }
- int alignOfTypedData() const
- {
- return qMax<int>(sizeof(void*), alignof(Data));
- }
};
template <typename T>
void QContiguousCache<T>::detach_helper()
{
- union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; } x;
-
- x.d = allocateData(d->alloc);
- x.d->ref.storeRelaxed(1);
- x.d->count = d->count;
- x.d->start = d->start;
- x.d->offset = d->offset;
- x.d->alloc = d->alloc;
-
- T *dest = x.p->array + x.d->start;
- T *src = p->array + d->start;
- int oldcount = x.d->count;
+ Data *x = allocateData(d->alloc);
+ x->ref.storeRelaxed(1);
+ x->count = d->count;
+ x->start = d->start;
+ x->offset = d->offset;
+ x->alloc = d->alloc;
+
+ T *dest = x->array + x->start;
+ T *src = d->array + d->start;
+ int oldcount = x->count;
while (oldcount--) {
if (QTypeInfo<T>::isComplex) {
new (dest) T(*src);
@@ -187,16 +168,16 @@ void QContiguousCache<T>::detach_helper()
*dest = *src;
}
dest++;
- if (dest == x.p->array + x.d->alloc)
- dest = x.p->array;
+ if (dest == x->array + x->alloc)
+ dest = x->array;
src++;
- if (src == p->array + d->alloc)
- src = p->array;
+ if (src == d->array + d->alloc)
+ src = d->array;
}
if (!d->ref.deref())
- freeData(p);
- d = x.d;
+ freeData(d);
+ d = x;
}
template <typename T>
@@ -206,39 +187,38 @@ void QContiguousCache<T>::setCapacity(int asize)
if (asize == d->alloc)
return;
detach();
- union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; } x;
- x.d = allocateData(asize);
- x.d->ref.storeRelaxed(1);
- x.d->alloc = asize;
- x.d->count = qMin(d->count, asize);
- x.d->offset = d->offset + d->count - x.d->count;
+ Data *x = allocateData(asize);
+ x->ref.storeRelaxed(1);
+ x->alloc = asize;
+ x->count = qMin(d->count, asize);
+ x->offset = d->offset + d->count - x->count;
if(asize)
- x.d->start = x.d->offset % x.d->alloc;
+ x->start = x->offset % x->alloc;
else
- x.d->start = 0;
+ x->start = 0;
- int oldcount = x.d->count;
+ int oldcount = x->count;
if(oldcount)
{
- T *dest = x.p->array + (x.d->start + x.d->count-1) % x.d->alloc;
- T *src = p->array + (d->start + d->count-1) % d->alloc;
+ T *dest = x->array + (x->start + x->count-1) % x->alloc;
+ T *src = d->array + (d->start + d->count-1) % d->alloc;
while (oldcount--) {
if (QTypeInfo<T>::isComplex) {
new (dest) T(*src);
} else {
*dest = *src;
}
- if (dest == x.p->array)
- dest = x.p->array + x.d->alloc;
+ if (dest == x->array)
+ dest = x->array + x->alloc;
dest--;
- if (src == p->array)
- src = p->array + d->alloc;
+ if (src == d->array)
+ src = d->array + d->alloc;
src--;
}
}
/* free old */
- freeData(p);
- d = x.d;
+ freeData(d);
+ d = x;
}
template <typename T>
@@ -247,31 +227,31 @@ void QContiguousCache<T>::clear()
if (d->ref.loadRelaxed() == 1) {
if (QTypeInfo<T>::isComplex) {
int oldcount = d->count;
- T * i = p->array + d->start;
- T * e = p->array + d->alloc;
+ T * i = d->array + d->start;
+ T * e = d->array + d->alloc;
while (oldcount--) {
i->~T();
i++;
if (i == e)
- i = p->array;
+ i = d->array;
}
}
d->count = d->start = d->offset = 0;
} else {
- union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; } x;
- x.d = allocateData(d->alloc);
- x.d->ref.storeRelaxed(1);
- x.d->alloc = d->alloc;
- x.d->count = x.d->start = x.d->offset = 0;
- if (!d->ref.deref()) freeData(p);
- d = x.d;
+ Data *x = allocateData(d->alloc);
+ x->ref.storeRelaxed(1);
+ x->alloc = d->alloc;
+ x->count = x->start = x->offset = 0;
+ if (!d->ref.deref())
+ freeData(d);
+ d = x;
}
}
template <typename T>
-inline QContiguousCacheData *QContiguousCache<T>::allocateData(int aalloc)
+inline typename QContiguousCache<T>::Data *QContiguousCache<T>::allocateData(int aalloc)
{
- return QContiguousCacheData::allocateData(sizeOfTypedData() + (aalloc - 1) * sizeof(T), alignOfTypedData());
+ return static_cast<Data *>(QContiguousCacheData::allocateData(sizeof(Data) + (aalloc - 1) * sizeof(T), alignof(Data)));
}
template <typename T>
@@ -289,7 +269,7 @@ QContiguousCache<T> &QContiguousCache<T>::operator=(const QContiguousCache<T> &o
{
other.d->ref.ref();
if (!d->ref.deref())
- freeData(p);
+ freeData(d);
d = other.d;
return *this;
}
@@ -315,16 +295,16 @@ void QContiguousCache<T>::freeData(Data *x)
{
if (QTypeInfo<T>::isComplex) {
int oldcount = d->count;
- T * i = p->array + d->start;
- T * e = p->array + d->alloc;
+ T * i = d->array + d->start;
+ T * e = d->array + d->alloc;
while (oldcount--) {
i->~T();
i++;
if (i == e)
- i = p->array;
+ i = d->array;
}
}
- x->freeData(x);
+ Data::freeData(x);
}
template <typename T>
void QContiguousCache<T>::append(const T &value)
@@ -334,10 +314,10 @@ void QContiguousCache<T>::append(const T &value)
detach();
if (QTypeInfo<T>::isComplex) {
if (d->count == d->alloc)
- (p->array + (d->start+d->count) % d->alloc)->~T();
- new (p->array + (d->start+d->count) % d->alloc) T(value);
+ (d->array + (d->start+d->count) % d->alloc)->~T();
+ new (d->array + (d->start+d->count) % d->alloc) T(value);
} else {
- p->array[(d->start+d->count) % d->alloc] = value;
+ d->array[(d->start+d->count) % d->alloc] = value;
}
if (d->count == d->alloc) {
@@ -365,12 +345,12 @@ void QContiguousCache<T>::prepend(const T &value)
d->count++;
else
if (d->count == d->alloc)
- (p->array + d->start)->~T();
+ (d->array + d->start)->~T();
if (QTypeInfo<T>::isComplex)
- new (p->array + d->start) T(value);
+ new (d->array + d->start) T(value);
else
- p->array[d->start] = value;
+ d->array[d->start] = value;
}
template<typename T>
@@ -382,10 +362,10 @@ void QContiguousCache<T>::insert(int pos, const T &value)
detach();
if (containsIndex(pos)) {
if (QTypeInfo<T>::isComplex) {
- (p->array + pos % d->alloc)->~T();
- new (p->array + pos % d->alloc) T(value);
+ (d->array + pos % d->alloc)->~T();
+ new (d->array + pos % d->alloc) T(value);
} else {
- p->array[pos % d->alloc] = value;
+ d->array[pos % d->alloc] = value;
}
} else if (pos == d->offset-1)
prepend(value);
@@ -398,18 +378,18 @@ void QContiguousCache<T>::insert(int pos, const T &value)
d->start = pos % d->alloc;
d->count = 1;
if (QTypeInfo<T>::isComplex)
- new (p->array + d->start) T(value);
+ new (d->array + d->start) T(value);
else
- p->array[d->start] = value;
+ d->array[d->start] = value;
}
}
template <typename T>
inline const T &QContiguousCache<T>::at(int pos) const
-{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache<T>::at", "index out of range"); return p->array[pos % d->alloc]; }
+{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache<T>::at", "index out of range"); return d->array[pos % d->alloc]; }
template <typename T>
inline const T &QContiguousCache<T>::operator[](int pos) const
-{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache<T>::at", "index out of range"); return p->array[pos % d->alloc]; }
+{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache<T>::at", "index out of range"); return d->array[pos % d->alloc]; }
template <typename T>
inline T &QContiguousCache<T>::operator[](int pos)
@@ -417,7 +397,7 @@ inline T &QContiguousCache<T>::operator[](int pos)
detach();
if (!containsIndex(pos))
insert(pos, T());
- return p->array[pos % d->alloc];
+ return d->array[pos % d->alloc];
}
template <typename T>
@@ -427,7 +407,7 @@ inline void QContiguousCache<T>::removeFirst()
detach();
d->count--;
if (QTypeInfo<T>::isComplex)
- (p->array + d->start)->~T();
+ (d->array + d->start)->~T();
d->start = (d->start + 1) % d->alloc;
d->offset++;
}
@@ -439,7 +419,7 @@ inline void QContiguousCache<T>::removeLast()
detach();
d->count--;
if (QTypeInfo<T>::isComplex)
- (p->array + (d->start + d->count) % d->alloc)->~T();
+ (d->array + (d->start + d->count) % d->alloc)->~T();
}
template <typename T>