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QVector - optimize removeLast (and takeLast + pop_back) 

In our benchmarks this makes removeLast more than twice as fast.
(That is on my core I7 laptop with gcc on linux).

It changes the alloc test to be an assert rather than an if.

Change-Id: Id55195b9b7880e54a89be4dd9d6228d94aff23c7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
bb10
Thorbjørn Martsum 2013-07-31 07:01:58 +02:00 committed by The Qt Project
parent 9b093871a6
commit 8b86443e36
1 changed files with 8 additions and 8 deletions
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16
src/corelib/tools/qvector.h
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@ -234,6 +234,7 @@ private:
friend class QRegion; // Optimization for QRegion::rects()
void reallocData(const int size, const int alloc, QArrayData::AllocationOptions options = QArrayData::Default);
void reallocData(const int sz) { reallocData(sz, d->alloc); }
void freeData(Data *d);
void defaultConstruct(T *from, T *to);
void copyConstruct(const T *srcFrom, const T *srcTo, T *dstFrom);
@ -563,18 +564,17 @@ void QVector<T>::append(const T &t)
}
template <typename T>
inline void QVector<T>::removeLast()
void QVector<T>::removeLast()
{
Q_ASSERT(!isEmpty());
Q_ASSERT(d->alloc);
if (d->alloc) {
if (d->ref.isShared()) {
reallocData(d->size - 1, int(d->alloc));
return;
}
if (QTypeInfo<T>::isComplex)
(d->data() + d->size - 1)->~T();
if (!d->ref.isShared()) {
--d->size;
if (QTypeInfo<T>::isComplex)
(d->data() + d->size)->~T();
} else {
reallocData(d->size - 1);
}
}