From 0283ca4cf2ad1c9e642b24f8376aa7179fa54599 Mon Sep 17 00:00:00 2001 From: Thiago Macieira Date: Thu, 22 Oct 2009 20:59:07 +0200 Subject: Add some STL compatibility for QContiguousCache and private inheritance The private inheritance ensures that we don't try to access the types under the wrong pointer. If we did that, we'd cause strict aliasing violations. Reviewed-by: Olivier Goffart --- src/corelib/tools/qcontiguouscache.h | 125 ++++++++++++++++++----------------- 1 file changed, 65 insertions(+), 60 deletions(-) diff --git a/src/corelib/tools/qcontiguouscache.h b/src/corelib/tools/qcontiguouscache.h index ad78d1f..862df61 100644 --- a/src/corelib/tools/qcontiguouscache.h +++ b/src/corelib/tools/qcontiguouscache.h @@ -62,6 +62,12 @@ struct Q_CORE_EXPORT QContiguousCacheData int start; int offset; uint sharable : 1; + // uint unused : 31; + + // 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) #ifdef QT_QCONTIGUOUSCACHE_DEBUG void dump() const; @@ -69,33 +75,32 @@ struct Q_CORE_EXPORT QContiguousCacheData }; template -struct QContiguousCacheTypedData +struct QContiguousCacheTypedData: private QContiguousCacheData { - QBasicAtomicInt ref; - int alloc; - int count; - int start; - int offset; - uint sharable : 1; - // uint unused : 31; - - // 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) - + // private inheritance to avoid aliasing warningss T array[1]; + + static inline void free(QContiguousCacheTypedData *data) { QContiguousCacheData::free(data); } }; template class QContiguousCache { typedef QContiguousCacheTypedData Data; - union { QContiguousCacheData *p; QContiguousCacheTypedData *d; }; + union { QContiguousCacheData *d; QContiguousCacheTypedData *p; }; public: + // STL compatibility + typedef T value_type; + typedef value_type* pointer; + typedef const value_type* const_pointer; + typedef value_type& reference; + typedef const value_type& const_reference; + typedef ptrdiff_t difference_type; + typedef int size_type; + explicit QContiguousCache(int capacity = 0); QContiguousCache(const QContiguousCache &v) : d(v.d) { d->ref.ref(); if (!d->sharable) detach_helper(); } - inline ~QContiguousCache() { if (!d) return; if (!d->ref.deref()) free(d); } + inline ~QContiguousCache() { if (!d) return; if (!d->ref.deref()) free(p); } inline void detach() { if (d->ref != 1) detach_helper(); } inline bool isDetached() const { return d->ref == 1; } @@ -128,10 +133,10 @@ 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 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]; } + 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]; } void removeFirst(); T takeFirst(); @@ -161,9 +166,9 @@ private: template void QContiguousCache::detach_helper() { - union { QContiguousCacheData *p; QContiguousCacheTypedData *d; } x; + union { QContiguousCacheData *d; QContiguousCacheTypedData *p; } x; - x.p = malloc(d->alloc); + x.d = malloc(d->alloc); x.d->ref = 1; x.d->count = d->count; x.d->start = d->start; @@ -171,8 +176,8 @@ void QContiguousCache::detach_helper() x.d->alloc = d->alloc; x.d->sharable = true; - T *dest = x.d->array + x.d->start; - T *src = d->array + d->start; + T *dest = x.p->array + x.d->start; + T *src = p->array + d->start; int oldcount = x.d->count; while (oldcount--) { if (QTypeInfo::isComplex) { @@ -181,15 +186,15 @@ void QContiguousCache::detach_helper() *dest = *src; } dest++; - if (dest == x.d->array + x.d->alloc) - dest = x.d->array; + if (dest == x.p->array + x.d->alloc) + dest = x.p->array; src++; - if (src == d->array + d->alloc) - src = d->array; + if (src == p->array + d->alloc) + src = p->array; } if (!d->ref.deref()) - free(d); + free(p); d = x.d; } @@ -205,8 +210,8 @@ void QContiguousCache::setCapacity(int asize) x.d->count = qMin(d->count, asize); x.d->offset = d->offset + d->count - x.d->count; x.d->start = x.d->offset % x.d->alloc; - T *dest = x.d->array + (x.d->start + x.d->count-1) % x.d->alloc; - T *src = d->array + (d->start + d->count-1) % d->alloc; + 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; int oldcount = x.d->count; while (oldcount--) { if (QTypeInfo::isComplex) { @@ -214,11 +219,11 @@ void QContiguousCache::setCapacity(int asize) } else { *dest = *src; } - if (dest == x.d->array) - dest = x.d->array + x.d->alloc; + if (dest == x.p->array) + dest = x.p->array + x.d->alloc; dest--; - if (src == d->array) - src = d->array + d->alloc; + if (src == p->array) + src = p->array + d->alloc; src--; } /* free old */ @@ -232,24 +237,24 @@ void QContiguousCache::clear() if (d->ref == 1) { if (QTypeInfo::isComplex) { int oldcount = d->count; - T * i = d->array + d->start; - T * e = d->array + d->alloc; + T * i = p->array + d->start; + T * e = p->array + d->alloc; while (oldcount--) { i->~T(); i++; if (i == e) - i = d->array; + i = p->array; } } d->count = d->start = d->offset = 0; } else { - union { QContiguousCacheData *p; QContiguousCacheTypedData *d; } x; - x.p = malloc(d->alloc); + union { QContiguousCacheData *d; QContiguousCacheTypedData *p; } x; + x.d = malloc(d->alloc); x.d->ref = 1; x.d->alloc = d->alloc; x.d->count = x.d->start = x.d->offset = 0; x.d->sharable = true; - if (!d->ref.deref()) free(d); + if (!d->ref.deref()) free(p); d = x.d; } } @@ -263,7 +268,7 @@ inline QContiguousCacheData *QContiguousCache::malloc(int aalloc) template QContiguousCache::QContiguousCache(int cap) { - p = malloc(cap); + d = malloc(cap); d->ref = 1; d->alloc = cap; d->count = d->start = d->offset = 0; @@ -303,13 +308,13 @@ void QContiguousCache::free(Data *x) { if (QTypeInfo::isComplex) { int oldcount = d->count; - T * i = d->array + d->start; - T * e = d->array + d->alloc; + T * i = p->array + d->start; + T * e = p->array + d->alloc; while (oldcount--) { i->~T(); i++; if (i == e) - i = d->array; + i = p->array; } } qFree(x); @@ -320,10 +325,10 @@ void QContiguousCache::append(const T &value) detach(); if (QTypeInfo::isComplex) { if (d->count == d->alloc) - (d->array + (d->start+d->count) % d->alloc)->~T(); - new (d->array + (d->start+d->count) % d->alloc) T(value); + (p->array + (d->start+d->count) % d->alloc)->~T(); + new (p->array + (d->start+d->count) % d->alloc) T(value); } else { - d->array[(d->start+d->count) % d->alloc] = value; + p->array[(d->start+d->count) % d->alloc] = value; } if (d->count == d->alloc) { @@ -349,12 +354,12 @@ void QContiguousCache::prepend(const T &value) d->count++; else if (d->count == d->alloc) - (d->array + d->start)->~T(); + (p->array + d->start)->~T(); if (QTypeInfo::isComplex) - new (d->array + d->start) T(value); + new (p->array + d->start) T(value); else - d->array[d->start] = value; + p->array[d->start] = value; } template @@ -364,9 +369,9 @@ void QContiguousCache::insert(int pos, const T &value) detach(); if (containsIndex(pos)) { if(QTypeInfo::isComplex) - new (d->array + pos % d->alloc) T(value); + new (p->array + pos % d->alloc) T(value); else - d->array[pos % d->alloc] = value; + p->array[pos % d->alloc] = value; } else if (pos == d->offset-1) prepend(value); else if (pos == d->offset+d->count) @@ -378,18 +383,18 @@ void QContiguousCache::insert(int pos, const T &value) d->start = pos % d->alloc; d->count = 1; if (QTypeInfo::isComplex) - new (d->array + d->start) T(value); + new (p->array + d->start) T(value); else - d->array[d->start] = value; + p->array[d->start] = value; } } template inline const T &QContiguousCache::at(int pos) const -{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache::at", "index out of range"); return d->array[pos % d->alloc]; } +{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache::at", "index out of range"); return p->array[pos % d->alloc]; } template inline const T &QContiguousCache::operator[](int pos) const -{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache::at", "index out of range"); return d->array[pos % d->alloc]; } +{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache::at", "index out of range"); return p->array[pos % d->alloc]; } template inline T &QContiguousCache::operator[](int pos) @@ -397,7 +402,7 @@ inline T &QContiguousCache::operator[](int pos) detach(); if (!containsIndex(pos)) insert(pos, T()); - return d->array[pos % d->alloc]; + return p->array[pos % d->alloc]; } template @@ -407,7 +412,7 @@ inline void QContiguousCache::removeFirst() detach(); d->count--; if (QTypeInfo::isComplex) - (d->array + d->start)->~T(); + (p->array + d->start)->~T(); d->start = (d->start + 1) % d->alloc; d->offset++; } @@ -419,7 +424,7 @@ inline void QContiguousCache::removeLast() detach(); d->count--; if (QTypeInfo::isComplex) - (d->array + (d->start + d->count) % d->alloc)->~T(); + (p->array + (d->start + d->count) % d->alloc)->~T(); } template -- cgit v0.12