Start moving QArrayData's size and data pointer to the main class

This requires that the allocation functions return two pointers: the d
pointer and the pointer to the actual data.

Ported QArrayDataPointer & SimpleVector to the inlined size & data.

For now, the size and offset members are not yet removed from
QArrayData, to let QVector, QByteArray and QString compile unmodified.

Change-Id: I8489300976723d75b8fd5831427b1e2bba486196
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 19 insertions, 10 deletions

diff --git a/src/corelib/tools/qarraydata.cpp b/src/corelib/tools/qarraydata.cpp
index aa7fac15ef..8052c2ca69 100644
--- a/src/corelib/tools/qarraydata.cpp
+++ b/src/corelib/tools/qarraydata.cpp
@@ -198,16 +198,19 @@ static QArrayData *reallocateData(QArrayData *header, size_t allocSize, uint opt
     return header;
 }
 
-QArrayData *QArrayData::allocate(size_t objectSize, size_t alignment,
+void *QArrayData::allocate(QArrayData **dptr, size_t objectSize, size_t alignment,
         size_t capacity, ArrayOptions options) noexcept
 {
+    Q_ASSERT(dptr);
     // Alignment is a power of two
     Q_ASSERT(alignment >= alignof(QArrayData)
             && !(alignment & (alignment - 1)));
 
-    if (capacity == 0)
+    if (capacity == 0) {
         // optimization for empty headers
-        return const_cast<QArrayData *>(&qt_array_empty);
+        *dptr = const_cast<QArrayData *>(&qt_array_empty);
+        return sharedNullData();
+    }
 
     size_t headerSize = sizeof(QArrayData);
 
@@ -225,14 +228,17 @@ QArrayData *QArrayData::allocate(size_t objectSize, size_t alignment,
     options |= AllocatedDataType | MutableData;
     options &= ~ImmutableHeader;
     QArrayData *header = allocateData(allocSize, options);
+    quintptr data = 0;
     if (header) {
-        quintptr data = (quintptr(header) + sizeof(QArrayData) + alignment - 1)
+        // find where offset should point to so that data() is aligned to alignment bytes
+        data = (quintptr(header) + sizeof(QArrayData) + alignment - 1)
                 & ~(alignment - 1);
         header->offset = data - quintptr(header);
         header->alloc = capacity;
     }
 
-    return header;
+    *dptr = header;
+    return reinterpret_cast<void *>(data);
 }
 
 QArrayData *QArrayData::prepareRawData(ArrayOptions options) Q_DECL_NOTHROW
@@ -243,8 +249,9 @@ QArrayData *QArrayData::prepareRawData(ArrayOptions options) Q_DECL_NOTHROW
     return header;
 }
 
-QArrayData *QArrayData::reallocateUnaligned(QArrayData *data, size_t objectSize, size_t capacity,
-                                            ArrayOptions options) noexcept
+QPair<QArrayData *, void *>
+QArrayData::reallocateUnaligned(QArrayData *data, void *dataPointer,
+                                size_t objectSize, size_t capacity, ArrayOptions options) noexcept
 {
     Q_ASSERT(data);
     Q_ASSERT(data->isMutable());
@@ -252,12 +259,14 @@ QArrayData *QArrayData::reallocateUnaligned(QArrayData *data, size_t objectSize,
 
     size_t headerSize = sizeof(QArrayData);
     size_t allocSize = calculateBlockSize(capacity, objectSize, headerSize, options);
+    qptrdiff offset = reinterpret_cast<char *>(dataPointer) - reinterpret_cast<char *>(data);
     options |= AllocatedDataType | MutableData;
-    options &= ~ImmutableHeader;
     QArrayData *header = reallocateData(data, allocSize, options);
-    if (header)
+    if (header) {
         header->alloc = capacity;
-    return header;
+        dataPointer = reinterpret_cast<char *>(header) + offset;
+    }
+    return qMakePair(static_cast<QArrayData *>(header), dataPointer);
 }
 
 void QArrayData::deallocate(QArrayData *data, size_t objectSize,