Allow allocating more than 2G items in a vector

Also adjust qCalculateBlockSize() to be able to handle large
allocations.

QVector::length() is currently still limited to 2G items, that will
get changed in a later commit.

Change-Id: I3a92fbfd7f281d30844c5fafa3b9a474bc347c19
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qarraydata.cpp

@@ -52,7 +52,7 @@ QT_BEGIN_NAMESPACE
  * containers to allocate memory and grow the memory block during append
  * operations.
  *
- * They take size_t parameters and return size_t so they will change sizes
+ * They take qsizetype parameters and return qsizetype so they will change sizes
  * according to the pointer width. However, knowing Qt containers store the
  * container size and element indexes in ints, these functions never return a
  * size larger than INT_MAX. This is done by casting the element count and
@@ -79,29 +79,21 @@ QT_BEGIN_NAMESPACE
     Both \a elementCount and \a headerSize can be zero, but \a elementSize
     cannot.
 
-    This function returns SIZE_MAX (~0) on overflow or if the memory block size
-    would not fit an int.
+    This function returns -1 on overflow or if the memory block size
+    would not fit a qsizetype.
 */
-size_t qCalculateBlockSize(size_t elementCount, size_t elementSize, size_t headerSize) noexcept
+qsizetype qCalculateBlockSize(qsizetype elementCount, qsizetype elementSize, qsizetype headerSize) noexcept
 {
-    unsigned count = unsigned(elementCount);
-    unsigned size = unsigned(elementSize);
-    unsigned header = unsigned(headerSize);
     Q_ASSERT(elementSize);
-    Q_ASSERT(size == elementSize);
-    Q_ASSERT(header == headerSize);
 
-    if (Q_UNLIKELY(count != elementCount))
-        return std::numeric_limits<size_t>::max();
+    size_t bytes;
+    if (Q_UNLIKELY(mul_overflow(size_t(elementSize), size_t(elementCount), &bytes)) ||
+            Q_UNLIKELY(add_overflow(bytes, size_t(headerSize), &bytes)))
+        return -1;
+    if (Q_UNLIKELY(qsizetype(bytes) < 0))
+        return -1;
 
-    unsigned bytes;
-    if (Q_UNLIKELY(mul_overflow(size, count, &bytes)) ||
-            Q_UNLIKELY(add_overflow(bytes, header, &bytes)))
-        return std::numeric_limits<size_t>::max();
-    if (Q_UNLIKELY(int(bytes) < 0))     // catches bytes >= 2GB
-        return std::numeric_limits<size_t>::max();
-
-    return bytes;
+    return qsizetype(bytes);
 }
 
 /*!
@@ -116,38 +108,39 @@ size_t qCalculateBlockSize(size_t elementCount, size_t elementSize, size_t heade
     Both \a elementCount and \a headerSize can be zero, but \a elementSize
     cannot.
 
-    This function returns SIZE_MAX (~0) on overflow or if the memory block size
-    would not fit an int.
+    This function returns -1 on overflow or if the memory block size
+    would not fit a qsizetype.
 
     \note The memory block may contain up to \a elementSize - 1 bytes more than
     needed.
 */
 CalculateGrowingBlockSizeResult
-qCalculateGrowingBlockSize(size_t elementCount, size_t elementSize, size_t headerSize) noexcept
+qCalculateGrowingBlockSize(qsizetype elementCount, qsizetype elementSize, qsizetype headerSize) noexcept
 {
     CalculateGrowingBlockSizeResult result = {
-        std::numeric_limits<size_t>::max(),std::numeric_limits<size_t>::max()
+        qsizetype(-1), qsizetype(-1)
     };
 
-    unsigned bytes = unsigned(qCalculateBlockSize(elementCount, elementSize, headerSize));
-    if (int(bytes) < 0)     // catches std::numeric_limits<size_t>::max()
+    qsizetype bytes = qCalculateBlockSize(elementCount, elementSize, headerSize);
+    if (bytes < 0)
         return result;
 
-    unsigned morebytes = qNextPowerOfTwo(bytes);
-    if (Q_UNLIKELY(int(morebytes) < 0)) {
-        // catches morebytes == 2GB
+    size_t morebytes = static_cast<size_t>(qNextPowerOfTwo(quint64(bytes)));
+    if (Q_UNLIKELY(qsizetype(morebytes) < 0)) {
         // grow by half the difference between bytes and morebytes
+        // this slows the growth and avoids trying to allocate exactly
+        // 2G of memory (on 32bit), something that many OSes can't deliver
         bytes += (morebytes - bytes) / 2;
     } else {
-        bytes = morebytes;
+        bytes = qsizetype(morebytes);
     }
 
-    result.elementCount = (bytes - unsigned(headerSize)) / unsigned(elementSize);
+    result.elementCount = (bytes - headerSize) / elementSize;
     result.size = result.elementCount * elementSize + headerSize;
     return result;
 }
 
-static inline size_t calculateBlockSize(size_t &capacity, size_t objectSize, size_t headerSize, uint options)
+static inline qsizetype calculateBlockSize(qsizetype &capacity, qsizetype objectSize, qsizetype headerSize, uint options)
 {
     // Calculate the byte size
     // allocSize = objectSize * capacity + headerSize, but checked for overflow
@@ -161,9 +154,9 @@ static inline size_t calculateBlockSize(size_t &capacity, size_t objectSize, siz
     }
 }
 
-static QArrayData *allocateData(size_t allocSize, uint options)
+static QArrayData *allocateData(qsizetype allocSize, uint options)
 {
-    QArrayData *header = static_cast<QArrayData *>(::malloc(allocSize));
+    QArrayData *header = static_cast<QArrayData *>(::malloc(size_t(allocSize)));
     if (header) {
         header->ref_.storeRelaxed(1);
         header->flags = options;
@@ -172,39 +165,38 @@ static QArrayData *allocateData(size_t allocSize, uint options)
     return header;
 }
 
-void *QArrayData::allocate(QArrayData **dptr, size_t objectSize, size_t alignment,
-        size_t capacity, ArrayOptions options) noexcept
+void *QArrayData::allocate(QArrayData **dptr, qsizetype objectSize, qsizetype alignment,
+        qsizetype capacity, ArrayOptions options) noexcept
 {
     Q_ASSERT(dptr);
     // Alignment is a power of two
-    Q_ASSERT(alignment >= alignof(QArrayData)
+    Q_ASSERT(alignment >= qsizetype(alignof(QArrayData))
             && !(alignment & (alignment - 1)));
 
     if (capacity == 0) {
         *dptr = nullptr;
         return nullptr;
     }
 
-    size_t headerSize = sizeof(QArrayData);
+    qsizetype headerSize = sizeof(QArrayData);
+    const qsizetype headerAlignment = alignof(QArrayData);
 
-    if (alignment > alignof(QArrayData)) {
+    if (alignment > headerAlignment) {
         // Allocate extra (alignment - Q_ALIGNOF(QArrayData)) padding bytes so we
         // can properly align the data array. This assumes malloc is able to
         // provide appropriate alignment for the header -- as it should!
-        headerSize += alignment - alignof(QArrayData);
+        headerSize += alignment - headerAlignment;
     }
+    Q_ASSERT(headerSize > 0);
 
-    if (headerSize > size_t(MaxAllocSize))
-        return nullptr;
-
-    size_t allocSize = calculateBlockSize(capacity, objectSize, headerSize, options);
+    qsizetype allocSize = calculateBlockSize(capacity, objectSize, headerSize, options);
     QArrayData *header = allocateData(allocSize, options);
     quintptr data = 0;
     if (header) {
         // find where offset should point to so that data() is aligned to alignment bytes
         data = (quintptr(header) + sizeof(QArrayData) + alignment - 1)
                 & ~(alignment - 1);
-        header->alloc = uint(capacity);
+        header->alloc = qsizetype(capacity);
     }
 
     *dptr = header;
@@ -213,12 +205,12 @@ void *QArrayData::allocate(QArrayData **dptr, size_t objectSize, size_t alignmen
 
 QPair<QArrayData *, void *>
 QArrayData::reallocateUnaligned(QArrayData *data, void *dataPointer,
-                                size_t objectSize, size_t capacity, ArrayOptions options) noexcept
+                                qsizetype objectSize, qsizetype capacity, ArrayOptions options) noexcept
 {
     Q_ASSERT(!data || !data->isShared());
 
-    size_t headerSize = sizeof(QArrayData);
-    size_t allocSize = calculateBlockSize(capacity, objectSize, headerSize, options);
+    qsizetype headerSize = sizeof(QArrayData);
+    qsizetype allocSize = calculateBlockSize(capacity, objectSize, headerSize, options);
     qptrdiff offset = dataPointer ? reinterpret_cast<char *>(dataPointer) - reinterpret_cast<char *>(data) : headerSize;
     QArrayData *header = static_cast<QArrayData *>(::realloc(data, size_t(allocSize)));
     if (header) {
@@ -229,11 +221,11 @@ QArrayData::reallocateUnaligned(QArrayData *data, void *dataPointer,
     return qMakePair(static_cast<QArrayData *>(header), dataPointer);
 }
 
-void QArrayData::deallocate(QArrayData *data, size_t objectSize,
-        size_t alignment) noexcept
+void QArrayData::deallocate(QArrayData *data, qsizetype objectSize,
+        qsizetype alignment) noexcept
 {
     // Alignment is a power of two
-    Q_ASSERT(alignment >= alignof(QArrayData)
+    Q_ASSERT(alignment >= qsizetype(alignof(QArrayData))
             && !(alignment & (alignment - 1)));
     Q_UNUSED(objectSize);
     Q_UNUSED(alignment);

src/corelib/tools/qarraydata.h

@@ -62,14 +62,14 @@ struct Q_CORE_EXPORT QArrayData
 
     QBasicAtomicInt ref_;
     uint flags;
-    uint alloc;
+    qsizetype alloc;
 
-    inline size_t allocatedCapacity() noexcept
+    inline qsizetype allocatedCapacity() noexcept
     {
         return alloc;
     }
 
-    inline size_t constAllocatedCapacity() const noexcept
+    inline qsizetype constAllocatedCapacity() const noexcept
     {
         return alloc;
     }
@@ -100,7 +100,7 @@ struct Q_CORE_EXPORT QArrayData
         return ref_.loadRelaxed() > 1;
     }
 
-    size_t detachCapacity(size_t newSize) const noexcept
+    qsizetype detachCapacity(qsizetype newSize) const noexcept
     {
         if (flags & CapacityReserved && newSize < constAllocatedCapacity())
             return constAllocatedCapacity();
@@ -119,12 +119,12 @@ struct Q_CORE_EXPORT QArrayData
 #if defined(Q_CC_GNU)
     __attribute__((__malloc__))
 #endif
-    static void *allocate(QArrayData **pdata, size_t objectSize, size_t alignment,
-            size_t capacity, ArrayOptions options = DefaultAllocationFlags) noexcept;
+    static void *allocate(QArrayData **pdata, qsizetype objectSize, qsizetype alignment,
+            qsizetype capacity, ArrayOptions options = DefaultAllocationFlags) noexcept;
     Q_REQUIRED_RESULT static QPair<QArrayData *, void *> reallocateUnaligned(QArrayData *data, void *dataPointer,
-            size_t objectSize, size_t newCapacity, ArrayOptions newOptions = DefaultAllocationFlags) Q_DECL_NOTHROW;
-    static void deallocate(QArrayData *data, size_t objectSize,
-            size_t alignment) noexcept;
+            qsizetype objectSize, qsizetype newCapacity, ArrayOptions newOptions = DefaultAllocationFlags) noexcept;
+    static void deallocate(QArrayData *data, qsizetype objectSize,
+            qsizetype alignment) noexcept;
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QArrayData::ArrayOptions)
@@ -202,7 +202,7 @@ struct QTypedArrayData
 
     class AlignmentDummy { QArrayData header; T data; };
 
-    Q_REQUIRED_RESULT static QPair<QTypedArrayData *, T *> allocate(size_t capacity,
+    Q_REQUIRED_RESULT static QPair<QTypedArrayData *, T *> allocate(qsizetype capacity,
             ArrayOptions options = DefaultAllocationFlags)
     {
         static_assert(sizeof(QTypedArrayData) == sizeof(QArrayData));
@@ -215,7 +215,7 @@ struct QTypedArrayData
     }
 
     static QPair<QTypedArrayData *, T *>
-    reallocateUnaligned(QTypedArrayData *data, T *dataPointer, size_t capacity,
+    reallocateUnaligned(QTypedArrayData *data, T *dataPointer, qsizetype capacity,
             ArrayOptions options = DefaultAllocationFlags)
     {
         static_assert(sizeof(QTypedArrayData) == sizeof(QArrayData));

src/corelib/tools/qtools_p.h

@@ -88,19 +88,19 @@ Q_DECL_CONSTEXPR inline int fromOct(uint c) noexcept
 
 // We typically need an extra bit for qNextPowerOfTwo when determining the next allocation size.
 enum {
-    MaxAllocSize = INT_MAX
+    MaxAllocSize = (std::numeric_limits<int>::max)()
 };
 
 struct CalculateGrowingBlockSizeResult {
-    size_t size;
-    size_t elementCount;
+    qsizetype size;
+    qsizetype elementCount;
 };
 
 // Implemented in qarraydata.cpp:
-size_t Q_CORE_EXPORT Q_DECL_CONST_FUNCTION
-qCalculateBlockSize(size_t elementCount, size_t elementSize, size_t headerSize = 0) noexcept;
+qsizetype Q_CORE_EXPORT Q_DECL_CONST_FUNCTION
+qCalculateBlockSize(qsizetype elementCount, qsizetype elementSize, qsizetype headerSize = 0) noexcept;
 CalculateGrowingBlockSizeResult Q_CORE_EXPORT Q_DECL_CONST_FUNCTION
-qCalculateGrowingBlockSize(size_t elementCount, size_t elementSize, size_t headerSize = 0) noexcept ;
+qCalculateGrowingBlockSize(qsizetype elementCount, qsizetype elementSize, qsizetype headerSize = 0) noexcept ;
 
 QT_END_NAMESPACE
 

tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp

@@ -1446,53 +1446,62 @@ void tst_QByteArray::toULongLong()
     QCOMPARE(b, ok);
 }
 
-static bool checkSize(size_t value, size_t min)
+static bool checkSize(qsizetype value, qsizetype min)
 {
-    return value >= min && value <= INT_MAX;
+    return value >= min && value <= std::numeric_limits<qsizetype>::max();
 }
 
 // global functions defined in qbytearray.cpp
 void tst_QByteArray::blockSizeCalculations()
 {
+    qsizetype MaxAllocSize = std::numeric_limits<qsizetype>::max();
+
     // Not very important, but please behave :-)
-    QCOMPARE(qCalculateBlockSize(0, 1), size_t(0));
+    QCOMPARE(qCalculateBlockSize(0, 1), qsizetype(0));
     QVERIFY(qCalculateGrowingBlockSize(0, 1).size <= MaxAllocSize);
     QVERIFY(qCalculateGrowingBlockSize(0, 1).elementCount <= MaxAllocSize);
 
     // boundary condition
-    QCOMPARE(qCalculateBlockSize(MaxAllocSize, 1), size_t(MaxAllocSize));
-    QCOMPARE(qCalculateBlockSize(MaxAllocSize/2, 2), size_t(MaxAllocSize) - 1);
-    QCOMPARE(qCalculateBlockSize(MaxAllocSize/2, 2, 1), size_t(MaxAllocSize));
-    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize, 1).size, size_t(MaxAllocSize));
-    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize, 1).elementCount, size_t(MaxAllocSize));
-    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize/2, 2, 1).size, size_t(MaxAllocSize));
-    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize/2, 2, 1).elementCount, size_t(MaxAllocSize)/2);
+    QCOMPARE(qCalculateBlockSize(MaxAllocSize, 1), qsizetype(MaxAllocSize));
+    QCOMPARE(qCalculateBlockSize(MaxAllocSize/2, 2), qsizetype(MaxAllocSize) - 1);
+    QCOMPARE(qCalculateBlockSize(MaxAllocSize/2, 2, 1), qsizetype(MaxAllocSize));
+    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize, 1).size, qsizetype(MaxAllocSize));
+    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize, 1).elementCount, qsizetype(MaxAllocSize));
+    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize/2, 2, 1).size, qsizetype(MaxAllocSize));
+    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize/2, 2, 1).elementCount, qsizetype(MaxAllocSize)/2);
 
     // error conditions
-    QCOMPARE(qCalculateBlockSize(uint(MaxAllocSize) + 1, 1), size_t(~0));
-    QCOMPARE(qCalculateBlockSize(size_t(-1), 1), size_t(~0));
-    QCOMPARE(qCalculateBlockSize(MaxAllocSize, 1, 1), size_t(~0));
-    QCOMPARE(qCalculateBlockSize(MaxAllocSize/2 + 1, 2), size_t(~0));
-    QCOMPARE(qCalculateGrowingBlockSize(uint(MaxAllocSize) + 1, 1).size, size_t(~0));
-    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize/2 + 1, 2).size, size_t(~0));
+    QCOMPARE(qCalculateBlockSize(qint64(MaxAllocSize) + 1, 1), qsizetype(-1));
+    QCOMPARE(qCalculateBlockSize(qsizetype(-1), 1), qsizetype(-1));
+    QCOMPARE(qCalculateBlockSize(MaxAllocSize, 1, 1), qsizetype(-1));
+    QCOMPARE(qCalculateBlockSize(MaxAllocSize/2 + 1, 2), qsizetype(-1));
+    QCOMPARE(qCalculateGrowingBlockSize(quint64(MaxAllocSize) + 1, 1).size, qsizetype(-1));
+    QCOMPARE(qCalculateGrowingBlockSize(MaxAllocSize/2 + 1, 2).size, qsizetype(-1));
 
     // overflow conditions
+#if QT_POINTER_SIZE == 4
     // on 32-bit platforms, (1 << 16) * (1 << 16) = (1 << 32) which is zero
-    QCOMPARE(qCalculateBlockSize(1 << 16, 1 << 16), size_t(~0));
-    QCOMPARE(qCalculateBlockSize(MaxAllocSize/4, 16), size_t(~0));
+    QCOMPARE(qCalculateBlockSize(1 << 16, 1 << 16), qsizetype(-1));
+    QCOMPARE(qCalculateBlockSize(MaxAllocSize/4, 16), qsizetype(-1));
     // on 32-bit platforms, (1 << 30) * 3 + (1 << 30) would overflow to zero
-    QCOMPARE(qCalculateBlockSize(1U << 30, 3, 1U << 30), size_t(~0));
-
+    QCOMPARE(qCalculateBlockSize(1U << 30, 3, 1U << 30), qsizetype(-1));
+#else
+    // on 64-bit platforms, (1 << 32) * (1 << 32) = (1 << 64) which is zero
+    QCOMPARE(qCalculateBlockSize(1LL << 32, 1LL << 32), qsizetype(-1));
+    QCOMPARE(qCalculateBlockSize(MaxAllocSize/4, 16), qsizetype(-1));
+    // on 64-bit platforms, (1 << 30) * 3 + (1 << 30) would overflow to zero
+    QCOMPARE(qCalculateBlockSize(1ULL << 62, 3, 1ULL << 62), qsizetype(-1));
+#endif
     // exact block sizes
     for (int i = 1; i < 1 << 31; i <<= 1) {
-        QCOMPARE(qCalculateBlockSize(0, 1, i), size_t(i));
-        QCOMPARE(qCalculateBlockSize(i, 1), size_t(i));
-        QCOMPARE(qCalculateBlockSize(i + i/2, 1), size_t(i + i/2));
+        QCOMPARE(qCalculateBlockSize(0, 1, i), qsizetype(i));
+        QCOMPARE(qCalculateBlockSize(i, 1), qsizetype(i));
+        QCOMPARE(qCalculateBlockSize(i + i/2, 1), qsizetype(i + i/2));
     }
     for (int i = 1; i < 1 << 30; i <<= 1) {
-        QCOMPARE(qCalculateBlockSize(i, 2), 2 * size_t(i));
-        QCOMPARE(qCalculateBlockSize(i, 2, 1), 2 * size_t(i) + 1);
-        QCOMPARE(qCalculateBlockSize(i, 2, 16), 2 * size_t(i) + 16);
+        QCOMPARE(qCalculateBlockSize(i, 2), 2 * qsizetype(i));
+        QCOMPARE(qCalculateBlockSize(i, 2, 1), 2 * qsizetype(i) + 1);
+        QCOMPARE(qCalculateBlockSize(i, 2, 16), 2 * qsizetype(i) + 16);
     }
 
     // growing sizes
@@ -1507,19 +1516,19 @@ void tst_QByteArray::blockSizeCalculations()
 
     // growth should be limited
     for (int elementSize = 1; elementSize < (1<<8); elementSize <<= 1) {
-        size_t alloc = 1;
+        qsizetype alloc = 1;
         forever {
             QVERIFY(checkSize(qCalculateGrowingBlockSize(alloc, elementSize).size, alloc * elementSize));
-            size_t newAlloc = qCalculateGrowingBlockSize(alloc, elementSize).elementCount;
+            qsizetype newAlloc = qCalculateGrowingBlockSize(alloc, elementSize).elementCount;
             QVERIFY(checkSize(newAlloc, alloc));
             if (newAlloc == alloc)
                 break;  // no growth, we're at limit
             alloc = newAlloc;
         }
-        QVERIFY(checkSize(alloc, size_t(MaxAllocSize) / elementSize));
+        QVERIFY(checkSize(alloc, qsizetype(MaxAllocSize) / elementSize));
 
         // the next allocation should be invalid
-        QCOMPARE(qCalculateGrowingBlockSize(alloc + 1, elementSize).size, size_t(~0));
+        QCOMPARE(qCalculateGrowingBlockSize(alloc + 1, elementSize).size, qsizetype(-1));
     }
 }