-ASSERT_CLASS_FITS_IN_CELL(JSArray);
-
-// Overview of JSArray
-//
-// Properties of JSArray objects may be stored in one of three locations:
-// * The regular JSObject property map.
-// * A storage vector.
-// * A sparse map of array entries.
-//
-// Properties with non-numeric identifiers, with identifiers that are not representable
-// as an unsigned integer, or where the value is greater than MAX_ARRAY_INDEX
-// (specifically, this is only one property - the value 0xFFFFFFFFU as an unsigned 32-bit
-// integer) are not considered array indices and will be stored in the JSObject property map.
-//
-// All properties with a numeric identifer, representable as an unsigned integer i,
-// where (i <= MAX_ARRAY_INDEX), are an array index and will be stored in either the
-// storage vector or the sparse map. An array index i will be handled in the following
-// fashion:
-//
-// * Where (i < MIN_SPARSE_ARRAY_INDEX) the value will be stored in the storage vector.
-// * Where (MIN_SPARSE_ARRAY_INDEX <= i <= MAX_STORAGE_VECTOR_INDEX) the value will either
-// be stored in the storage vector or in the sparse array, depending on the density of
-// data that would be stored in the vector (a vector being used where at least
-// (1 / minDensityMultiplier) of the entries would be populated).
-// * Where (MAX_STORAGE_VECTOR_INDEX < i <= MAX_ARRAY_INDEX) the value will always be stored
-// in the sparse array.
-
-// The definition of MAX_STORAGE_VECTOR_LENGTH is dependant on the definition storageSize
-// function below - the MAX_STORAGE_VECTOR_LENGTH limit is defined such that the storage
-// size calculation cannot overflow. (sizeof(ArrayStorage) - sizeof(JSValue)) +
-// (vectorLength * sizeof(JSValue)) must be <= 0xFFFFFFFFU (which is maximum value of size_t).
-#define MAX_STORAGE_VECTOR_LENGTH static_cast<unsigned>((0xFFFFFFFFU - (sizeof(ArrayStorage) - sizeof(JSValue))) / sizeof(JSValue))
-
-// These values have to be macros to be used in max() and min() without introducing
-// a PIC branch in Mach-O binaries, see <rdar://problem/5971391>.
-#define MIN_SPARSE_ARRAY_INDEX 10000U
-#define MAX_STORAGE_VECTOR_INDEX (MAX_STORAGE_VECTOR_LENGTH - 1)
-// 0xFFFFFFFF is a bit weird -- is not an array index even though it's an integer.
-#define MAX_ARRAY_INDEX 0xFFFFFFFEU
-
-// The value BASE_VECTOR_LEN is the maximum number of vector elements we'll allocate
-// for an array that was created with a sepcified length (e.g. a = new Array(123))
-#define BASE_VECTOR_LEN 4U
-
-// The upper bound to the size we'll grow a zero length array when the first element
-// is added.
-#define FIRST_VECTOR_GROW 4U
-
-// Our policy for when to use a vector and when to use a sparse map.
-// For all array indices under MIN_SPARSE_ARRAY_INDEX, we always use a vector.
-// When indices greater than MIN_SPARSE_ARRAY_INDEX are involved, we use a vector
-// as long as it is 1/8 full. If more sparse than that, we use a map.
-static const unsigned minDensityMultiplier = 8;
-
-const ClassInfo JSArray::s_info = {"Array", &JSNonFinalObject::s_info, 0, 0};
-
-// We keep track of the size of the last array after it was grown. We use this
-// as a simple heuristic for as the value to grow the next array from size 0.
-// This value is capped by the constant FIRST_VECTOR_GROW defined above.
-static unsigned lastArraySize = 0;
-
-static inline size_t storageSize(unsigned vectorLength)
-{
- ASSERT(vectorLength <= MAX_STORAGE_VECTOR_LENGTH);
-
- // MAX_STORAGE_VECTOR_LENGTH is defined such that provided (vectorLength <= MAX_STORAGE_VECTOR_LENGTH)
- // - as asserted above - the following calculation cannot overflow.
- size_t size = (sizeof(ArrayStorage) - sizeof(JSValue)) + (vectorLength * sizeof(JSValue));
- // Assertion to detect integer overflow in previous calculation (should not be possible, provided that
- // MAX_STORAGE_VECTOR_LENGTH is correctly defined).
- ASSERT(((size - (sizeof(ArrayStorage) - sizeof(JSValue))) / sizeof(JSValue) == vectorLength) && (size >= (sizeof(ArrayStorage) - sizeof(JSValue))));
-
- return size;
-}
-
-static inline bool isDenseEnoughForVector(unsigned length, unsigned numValues)
-{
- return length / minDensityMultiplier <= numValues;
-}
-
-#if !CHECK_ARRAY_CONSISTENCY
-
-inline void JSArray::checkConsistency(ConsistencyCheckType)
-{
-}
-
-#endif
-
-JSArray::JSArray(VPtrStealingHackType)
- : JSNonFinalObject(VPtrStealingHack)
-{
-}
-
-JSArray::JSArray(JSGlobalData& globalData, Structure* structure)
- : JSNonFinalObject(globalData, structure)
-{
- ASSERT(inherits(&s_info));
-
- unsigned initialCapacity = 0;
-
- m_storage = static_cast<ArrayStorage*>(fastZeroedMalloc(storageSize(initialCapacity)));
- m_storage->m_allocBase = m_storage;
- m_indexBias = 0;
- m_vectorLength = initialCapacity;
projects / apple / javascriptcore.git / blobdiff