// Copyright 2012 the V8 project authors. All rights reserved. // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following // disclaimer in the documentation and/or other materials provided // with the distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. #include "v8.h" #include "objects.h" #include "elements.h" #include "utils.h" // Each concrete ElementsAccessor can handle exactly one ElementsKind, // several abstract ElementsAccessor classes are used to allow sharing // common code. // // Inheritance hierarchy: // - ElementsAccessorBase (abstract) // - FastElementsAccessor (abstract) // - FastObjectElementsAccessor // - FastDoubleElementsAccessor // - ExternalElementsAccessor (abstract) // - ExternalByteElementsAccessor // - ExternalUnsignedByteElementsAccessor // - ExternalShortElementsAccessor // - ExternalUnsignedShortElementsAccessor // - ExternalIntElementsAccessor // - ExternalUnsignedIntElementsAccessor // - ExternalFloatElementsAccessor // - ExternalDoubleElementsAccessor // - PixelElementsAccessor // - DictionaryElementsAccessor // - NonStrictArgumentsElementsAccessor namespace v8 { namespace internal { // First argument in list is the accessor class, the second argument is the // accessor ElementsKind, and the third is the backing store class. Use the // fast element handler for smi-only arrays. The implementation is currently // identical. Note that the order must match that of the ElementsKind enum for // the |accessor_array[]| below to work. #define ELEMENTS_LIST(V) \ V(FastObjectElementsAccessor, FAST_SMI_ONLY_ELEMENTS, FixedArray) \ V(FastObjectElementsAccessor, FAST_ELEMENTS, FixedArray) \ V(FastDoubleElementsAccessor, FAST_DOUBLE_ELEMENTS, FixedDoubleArray) \ V(DictionaryElementsAccessor, DICTIONARY_ELEMENTS, \ SeededNumberDictionary) \ V(NonStrictArgumentsElementsAccessor, NON_STRICT_ARGUMENTS_ELEMENTS, \ FixedArray) \ V(ExternalByteElementsAccessor, EXTERNAL_BYTE_ELEMENTS, \ ExternalByteArray) \ V(ExternalUnsignedByteElementsAccessor, \ EXTERNAL_UNSIGNED_BYTE_ELEMENTS, ExternalUnsignedByteArray) \ V(ExternalShortElementsAccessor, EXTERNAL_SHORT_ELEMENTS, \ ExternalShortArray) \ V(ExternalUnsignedShortElementsAccessor, \ EXTERNAL_UNSIGNED_SHORT_ELEMENTS, ExternalUnsignedShortArray) \ V(ExternalIntElementsAccessor, EXTERNAL_INT_ELEMENTS, \ ExternalIntArray) \ V(ExternalUnsignedIntElementsAccessor, \ EXTERNAL_UNSIGNED_INT_ELEMENTS, ExternalUnsignedIntArray) \ V(ExternalFloatElementsAccessor, \ EXTERNAL_FLOAT_ELEMENTS, ExternalFloatArray) \ V(ExternalDoubleElementsAccessor, \ EXTERNAL_DOUBLE_ELEMENTS, ExternalDoubleArray) \ V(PixelElementsAccessor, EXTERNAL_PIXEL_ELEMENTS, ExternalPixelArray) template<ElementsKind Kind> class ElementsKindTraits { public: typedef FixedArrayBase BackingStore; }; #define ELEMENTS_TRAITS(Class, KindParam, Store) \ template<> class ElementsKindTraits<KindParam> { \ public: \ static const ElementsKind Kind = KindParam; \ typedef Store BackingStore; \ }; ELEMENTS_LIST(ELEMENTS_TRAITS) #undef ELEMENTS_TRAITS ElementsAccessor** ElementsAccessor::elements_accessors_; static bool HasKey(FixedArray* array, Object* key) { int len0 = array->length(); for (int i = 0; i < len0; i++) { Object* element = array->get(i); if (element->IsSmi() && element == key) return true; if (element->IsString() && key->IsString() && String::cast(element)->Equals(String::cast(key))) { return true; } } return false; } static Failure* ThrowArrayLengthRangeError(Heap* heap) { HandleScope scope(heap->isolate()); return heap->isolate()->Throw( *heap->isolate()->factory()->NewRangeError("invalid_array_length", HandleVector<Object>(NULL, 0))); } void CopyObjectToObjectElements(FixedArray* from, ElementsKind from_kind, uint32_t from_start, FixedArray* to, ElementsKind to_kind, uint32_t to_start, int raw_copy_size) { ASSERT(to->map() != HEAP->fixed_cow_array_map()); ASSERT(from_kind == FAST_ELEMENTS || from_kind == FAST_SMI_ONLY_ELEMENTS); ASSERT(to_kind == FAST_ELEMENTS || to_kind == FAST_SMI_ONLY_ELEMENTS); int copy_size = raw_copy_size; if (raw_copy_size < 0) { ASSERT(raw_copy_size == ElementsAccessor::kCopyToEnd || raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole); copy_size = Min(from->length() - from_start, to->length() - to_start); #ifdef DEBUG // FAST_ELEMENT arrays cannot be uninitialized. Ensure they are already // marked with the hole. if (raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole) { for (int i = to_start + copy_size; i < to->length(); ++i) { ASSERT(to->get(i)->IsTheHole()); } } #endif } ASSERT((copy_size + static_cast<int>(to_start)) <= to->length() && (copy_size + static_cast<int>(from_start)) <= from->length()); if (copy_size == 0) return; Address to_address = to->address() + FixedArray::kHeaderSize; Address from_address = from->address() + FixedArray::kHeaderSize; CopyWords(reinterpret_cast<Object**>(to_address) + to_start, reinterpret_cast<Object**>(from_address) + from_start, copy_size); if (from_kind == FAST_ELEMENTS && to_kind == FAST_ELEMENTS) { Heap* heap = from->GetHeap(); if (!heap->InNewSpace(to)) { heap->RecordWrites(to->address(), to->OffsetOfElementAt(to_start), copy_size); } heap->incremental_marking()->RecordWrites(to); } } static void CopyDictionaryToObjectElements(SeededNumberDictionary* from, uint32_t from_start, FixedArray* to, ElementsKind to_kind, uint32_t to_start, int raw_copy_size) { int copy_size = raw_copy_size; Heap* heap = from->GetHeap(); if (raw_copy_size < 0) { ASSERT(raw_copy_size == ElementsAccessor::kCopyToEnd || raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole); copy_size = from->max_number_key() + 1 - from_start; #ifdef DEBUG // FAST_ELEMENT arrays cannot be uninitialized. Ensure they are already // marked with the hole. if (raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole) { for (int i = to_start + copy_size; i < to->length(); ++i) { ASSERT(to->get(i)->IsTheHole()); } } #endif } ASSERT(to != from); ASSERT(to_kind == FAST_ELEMENTS || to_kind == FAST_SMI_ONLY_ELEMENTS); if (copy_size == 0) return; uint32_t to_length = to->length(); if (to_start + copy_size > to_length) { copy_size = to_length - to_start; } for (int i = 0; i < copy_size; i++) { int entry = from->FindEntry(i + from_start); if (entry != SeededNumberDictionary::kNotFound) { Object* value = from->ValueAt(entry); ASSERT(!value->IsTheHole()); to->set(i + to_start, value, SKIP_WRITE_BARRIER); } else { to->set_the_hole(i + to_start); } } if (to_kind == FAST_ELEMENTS) { if (!heap->InNewSpace(to)) { heap->RecordWrites(to->address(), to->OffsetOfElementAt(to_start), copy_size); } heap->incremental_marking()->RecordWrites(to); } } MUST_USE_RESULT static MaybeObject* CopyDoubleToObjectElements( FixedDoubleArray* from, uint32_t from_start, FixedArray* to, ElementsKind to_kind, uint32_t to_start, int raw_copy_size) { ASSERT(to_kind == FAST_ELEMENTS || to_kind == FAST_SMI_ONLY_ELEMENTS); int copy_size = raw_copy_size; if (raw_copy_size < 0) { ASSERT(raw_copy_size == ElementsAccessor::kCopyToEnd || raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole); copy_size = Min(from->length() - from_start, to->length() - to_start); #ifdef DEBUG // FAST_ELEMENT arrays cannot be uninitialized. Ensure they are already // marked with the hole. if (raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole) { for (int i = to_start + copy_size; i < to->length(); ++i) { ASSERT(to->get(i)->IsTheHole()); } } #endif } ASSERT((copy_size + static_cast<int>(to_start)) <= to->length() && (copy_size + static_cast<int>(from_start)) <= from->length()); if (copy_size == 0) return from; for (int i = 0; i < copy_size; ++i) { if (to_kind == FAST_SMI_ONLY_ELEMENTS) { UNIMPLEMENTED(); return Failure::Exception(); } else { MaybeObject* maybe_value = from->get(i + from_start); Object* value; ASSERT(to_kind == FAST_ELEMENTS); // Because FAST_DOUBLE_ELEMENTS -> FAST_ELEMENT allocate HeapObjects // iteratively, the allocate must succeed within a single GC cycle, // otherwise the retry after the GC will also fail. In order to ensure // that no GC is triggered, allocate HeapNumbers from old space if they // can't be taken from new space. if (!maybe_value->ToObject(&value)) { ASSERT(maybe_value->IsRetryAfterGC() || maybe_value->IsOutOfMemory()); Heap* heap = from->GetHeap(); MaybeObject* maybe_value_object = heap->AllocateHeapNumber(from->get_scalar(i + from_start), TENURED); if (!maybe_value_object->ToObject(&value)) return maybe_value_object; } to->set(i + to_start, value, UPDATE_WRITE_BARRIER); } } return to; } static void CopyDoubleToDoubleElements(FixedDoubleArray* from, uint32_t from_start, FixedDoubleArray* to, uint32_t to_start, int raw_copy_size) { int copy_size = raw_copy_size; if (raw_copy_size < 0) { ASSERT(raw_copy_size == ElementsAccessor::kCopyToEnd || raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole); copy_size = Min(from->length() - from_start, to->length() - to_start); if (raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole) { for (int i = to_start + copy_size; i < to->length(); ++i) { to->set_the_hole(i); } } } ASSERT((copy_size + static_cast<int>(to_start)) <= to->length() && (copy_size + static_cast<int>(from_start)) <= from->length()); if (copy_size == 0) return; Address to_address = to->address() + FixedDoubleArray::kHeaderSize; Address from_address = from->address() + FixedDoubleArray::kHeaderSize; to_address += kDoubleSize * to_start; from_address += kDoubleSize * from_start; int words_per_double = (kDoubleSize / kPointerSize); CopyWords(reinterpret_cast<Object**>(to_address), reinterpret_cast<Object**>(from_address), words_per_double * copy_size); } static void CopyObjectToDoubleElements(FixedArray* from, uint32_t from_start, FixedDoubleArray* to, uint32_t to_start, int raw_copy_size) { int copy_size = raw_copy_size; if (raw_copy_size < 0) { ASSERT(raw_copy_size == ElementsAccessor::kCopyToEnd || raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole); copy_size = from->length() - from_start; if (raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole) { for (int i = to_start + copy_size; i < to->length(); ++i) { to->set_the_hole(i); } } } ASSERT((copy_size + static_cast<int>(to_start)) <= to->length() && (copy_size + static_cast<int>(from_start)) <= from->length()); if (copy_size == 0) return; for (int i = 0; i < copy_size; i++) { Object* hole_or_object = from->get(i + from_start); if (hole_or_object->IsTheHole()) { to->set_the_hole(i + to_start); } else { to->set(i + to_start, hole_or_object->Number()); } } } static void CopyDictionaryToDoubleElements(SeededNumberDictionary* from, uint32_t from_start, FixedDoubleArray* to, uint32_t to_start, int raw_copy_size) { int copy_size = raw_copy_size; if (copy_size < 0) { ASSERT(copy_size == ElementsAccessor::kCopyToEnd || copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole); copy_size = from->max_number_key() + 1 - from_start; if (raw_copy_size == ElementsAccessor::kCopyToEndAndInitializeToHole) { for (int i = to_start + copy_size; i < to->length(); ++i) { to->set_the_hole(i); } } } if (copy_size == 0) return; uint32_t to_length = to->length(); if (to_start + copy_size > to_length) { copy_size = to_length - to_start; } for (int i = 0; i < copy_size; i++) { int entry = from->FindEntry(i + from_start); if (entry != SeededNumberDictionary::kNotFound) { to->set(i + to_start, from->ValueAt(entry)->Number()); } else { to->set_the_hole(i + to_start); } } } // Base class for element handler implementations. Contains the // the common logic for objects with different ElementsKinds. // Subclasses must specialize method for which the element // implementation differs from the base class implementation. // // This class is intended to be used in the following way: // // class SomeElementsAccessor : // public ElementsAccessorBase<SomeElementsAccessor, // BackingStoreClass> { // ... // } // // This is an example of the Curiously Recurring Template Pattern (see // http://en.wikipedia.org/wiki/Curiously_recurring_template_pattern). We use // CRTP to guarantee aggressive compile time optimizations (i.e. inlining and // specialization of SomeElementsAccessor methods). template <typename ElementsAccessorSubclass, typename ElementsTraitsParam> class ElementsAccessorBase : public ElementsAccessor { protected: explicit ElementsAccessorBase(const char* name) : ElementsAccessor(name) { } typedef ElementsTraitsParam ElementsTraits; typedef typename ElementsTraitsParam::BackingStore BackingStore; virtual ElementsKind kind() const { return ElementsTraits::Kind; } static bool HasElementImpl(Object* receiver, JSObject* holder, uint32_t key, BackingStore* backing_store) { MaybeObject* element = ElementsAccessorSubclass::GetImpl(receiver, holder, key, backing_store); return !element->IsTheHole(); } virtual bool HasElement(Object* receiver, JSObject* holder, uint32_t key, FixedArrayBase* backing_store) { if (backing_store == NULL) { backing_store = holder->elements(); } return ElementsAccessorSubclass::HasElementImpl( receiver, holder, key, BackingStore::cast(backing_store)); } virtual MaybeObject* Get(Object* receiver, JSObject* holder, uint32_t key, FixedArrayBase* backing_store) { if (backing_store == NULL) { backing_store = holder->elements(); } return ElementsAccessorSubclass::GetImpl( receiver, holder, key, BackingStore::cast(backing_store)); } static MaybeObject* GetImpl(Object* receiver, JSObject* obj, uint32_t key, BackingStore* backing_store) { return (key < ElementsAccessorSubclass::GetCapacityImpl(backing_store)) ? backing_store->get(key) : backing_store->GetHeap()->the_hole_value(); } virtual MaybeObject* SetLength(JSArray* array, Object* length) { return ElementsAccessorSubclass::SetLengthImpl( array, length, BackingStore::cast(array->elements())); } static MaybeObject* SetLengthImpl(JSObject* obj, Object* length, BackingStore* backing_store); virtual MaybeObject* SetCapacityAndLength(JSArray* array, int capacity, int length) { return ElementsAccessorSubclass::SetFastElementsCapacityAndLength( array, capacity, length); } static MaybeObject* SetFastElementsCapacityAndLength(JSObject* obj, int capacity, int length) { UNIMPLEMENTED(); return obj; } virtual MaybeObject* Delete(JSObject* obj, uint32_t key, JSReceiver::DeleteMode mode) = 0; static MaybeObject* CopyElementsImpl(FixedArrayBase* from, uint32_t from_start, FixedArrayBase* to, ElementsKind to_kind, uint32_t to_start, int copy_size) { UNREACHABLE(); return NULL; } virtual MaybeObject* CopyElements(JSObject* from_holder, uint32_t from_start, FixedArrayBase* to, ElementsKind to_kind, uint32_t to_start, int copy_size, FixedArrayBase* from) { if (from == NULL) { from = from_holder->elements(); } if (from->length() == 0) { return from; } return ElementsAccessorSubclass::CopyElementsImpl( from, from_start, to, to_kind, to_start, copy_size); } virtual MaybeObject* AddElementsToFixedArray(Object* receiver, JSObject* holder, FixedArray* to, FixedArrayBase* from) { int len0 = to->length(); #ifdef DEBUG if (FLAG_enable_slow_asserts) { for (int i = 0; i < len0; i++) { ASSERT(!to->get(i)->IsTheHole()); } } #endif if (from == NULL) { from = holder->elements(); } BackingStore* backing_store = BackingStore::cast(from); uint32_t len1 = ElementsAccessorSubclass::GetCapacityImpl(backing_store); // Optimize if 'other' is empty. // We cannot optimize if 'this' is empty, as other may have holes. if (len1 == 0) return to; // Compute how many elements are not in other. uint32_t extra = 0; for (uint32_t y = 0; y < len1; y++) { uint32_t key = ElementsAccessorSubclass::GetKeyForIndexImpl(backing_store, y); if (ElementsAccessorSubclass::HasElementImpl( receiver, holder, key, backing_store)) { MaybeObject* maybe_value = ElementsAccessorSubclass::GetImpl(receiver, holder, key, backing_store); Object* value; if (!maybe_value->ToObject(&value)) return maybe_value; ASSERT(!value->IsTheHole()); if (!HasKey(to, value)) { extra++; } } } if (extra == 0) return to; // Allocate the result FixedArray* result; MaybeObject* maybe_obj = backing_store->GetHeap()->AllocateFixedArray(len0 + extra); if (!maybe_obj->To<FixedArray>(&result)) return maybe_obj; // Fill in the content { AssertNoAllocation no_gc; WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc); for (int i = 0; i < len0; i++) { Object* e = to->get(i); ASSERT(e->IsString() || e->IsNumber()); result->set(i, e, mode); } } // Fill in the extra values. uint32_t index = 0; for (uint32_t y = 0; y < len1; y++) { uint32_t key = ElementsAccessorSubclass::GetKeyForIndexImpl(backing_store, y); if (ElementsAccessorSubclass::HasElementImpl( receiver, holder, key, backing_store)) { MaybeObject* maybe_value = ElementsAccessorSubclass::GetImpl(receiver, holder, key, backing_store); Object* value; if (!maybe_value->ToObject(&value)) return maybe_value; if (!value->IsTheHole() && !HasKey(to, value)) { result->set(len0 + index, value); index++; } } } ASSERT(extra == index); return result; } protected: static uint32_t GetCapacityImpl(BackingStore* backing_store) { return backing_store->length(); } virtual uint32_t GetCapacity(FixedArrayBase* backing_store) { return ElementsAccessorSubclass::GetCapacityImpl( BackingStore::cast(backing_store)); } static uint32_t GetKeyForIndexImpl(BackingStore* backing_store, uint32_t index) { return index; } virtual uint32_t GetKeyForIndex(FixedArrayBase* backing_store, uint32_t index) { return ElementsAccessorSubclass::GetKeyForIndexImpl( BackingStore::cast(backing_store), index); } private: DISALLOW_COPY_AND_ASSIGN(ElementsAccessorBase); }; // Super class for all fast element arrays. template<typename FastElementsAccessorSubclass, typename KindTraits, int ElementSize> class FastElementsAccessor : public ElementsAccessorBase<FastElementsAccessorSubclass, KindTraits> { public: explicit FastElementsAccessor(const char* name) : ElementsAccessorBase<FastElementsAccessorSubclass, KindTraits>(name) {} protected: friend class ElementsAccessorBase<FastElementsAccessorSubclass, KindTraits>; typedef typename KindTraits::BackingStore BackingStore; // Adjusts the length of the fast backing store or returns the new length or // undefined in case conversion to a slow backing store should be performed. static MaybeObject* SetLengthWithoutNormalize(BackingStore* backing_store, JSArray* array, Object* length_object, uint32_t length) { uint32_t old_capacity = backing_store->length(); // Check whether the backing store should be shrunk. if (length <= old_capacity) { if (array->HasFastTypeElements()) { MaybeObject* maybe_obj = array->EnsureWritableFastElements(); if (!maybe_obj->To(&backing_store)) return maybe_obj; } if (2 * length <= old_capacity) { // If more than half the elements won't be used, trim the array. if (length == 0) { array->initialize_elements(); } else { backing_store->set_length(length); Address filler_start = backing_store->address() + BackingStore::OffsetOfElementAt(length); int filler_size = (old_capacity - length) * ElementSize; array->GetHeap()->CreateFillerObjectAt(filler_start, filler_size); } } else { // Otherwise, fill the unused tail with holes. int old_length = FastD2I(array->length()->Number()); for (int i = length; i < old_length; i++) { backing_store->set_the_hole(i); } } return length_object; } // Check whether the backing store should be expanded. uint32_t min = JSObject::NewElementsCapacity(old_capacity); uint32_t new_capacity = length > min ? length : min; if (!array->ShouldConvertToSlowElements(new_capacity)) { MaybeObject* result = FastElementsAccessorSubclass:: SetFastElementsCapacityAndLength(array, new_capacity, length); if (result->IsFailure()) return result; return length_object; } // Request conversion to slow elements. return array->GetHeap()->undefined_value(); } }; class FastObjectElementsAccessor : public FastElementsAccessor<FastObjectElementsAccessor, ElementsKindTraits<FAST_ELEMENTS>, kPointerSize> { public: explicit FastObjectElementsAccessor(const char* name) : FastElementsAccessor<FastObjectElementsAccessor, ElementsKindTraits<FAST_ELEMENTS>, kPointerSize>(name) {} static MaybeObject* DeleteCommon(JSObject* obj, uint32_t key) { ASSERT(obj->HasFastElements() || obj->HasFastSmiOnlyElements() || obj->HasFastArgumentsElements()); Heap* heap = obj->GetHeap(); FixedArray* backing_store = FixedArray::cast(obj->elements()); if (backing_store->map() == heap->non_strict_arguments_elements_map()) { backing_store = FixedArray::cast(backing_store->get(1)); } else { Object* writable; MaybeObject* maybe = obj->EnsureWritableFastElements(); if (!maybe->ToObject(&writable)) return maybe; backing_store = FixedArray::cast(writable); } uint32_t length = static_cast<uint32_t>( obj->IsJSArray() ? Smi::cast(JSArray::cast(obj)->length())->value() : backing_store->length()); if (key < length) { backing_store->set_the_hole(key); // If an old space backing store is larger than a certain size and // has too few used values, normalize it. // To avoid doing the check on every delete we require at least // one adjacent hole to the value being deleted. Object* hole = heap->the_hole_value(); const int kMinLengthForSparsenessCheck = 64; if (backing_store->length() >= kMinLengthForSparsenessCheck && !heap->InNewSpace(backing_store) && ((key > 0 && backing_store->get(key - 1) == hole) || (key + 1 < length && backing_store->get(key + 1) == hole))) { int num_used = 0; for (int i = 0; i < backing_store->length(); ++i) { if (backing_store->get(i) != hole) ++num_used; // Bail out early if more than 1/4 is used. if (4 * num_used > backing_store->length()) break; } if (4 * num_used <= backing_store->length()) { MaybeObject* result = obj->NormalizeElements(); if (result->IsFailure()) return result; } } } return heap->true_value(); } static MaybeObject* CopyElementsImpl(FixedArrayBase* from, uint32_t from_start, FixedArrayBase* to, ElementsKind to_kind, uint32_t to_start, int copy_size) { switch (to_kind) { case FAST_SMI_ONLY_ELEMENTS: case FAST_ELEMENTS: { CopyObjectToObjectElements( FixedArray::cast(from), ElementsTraits::Kind, from_start, FixedArray::cast(to), to_kind, to_start, copy_size); return from; } case FAST_DOUBLE_ELEMENTS: CopyObjectToDoubleElements( FixedArray::cast(from), from_start, FixedDoubleArray::cast(to), to_start, copy_size); return from; default: UNREACHABLE(); } return to->GetHeap()->undefined_value(); } static MaybeObject* SetFastElementsCapacityAndLength(JSObject* obj, uint32_t capacity, uint32_t length) { JSObject::SetFastElementsCapacityMode set_capacity_mode = obj->HasFastSmiOnlyElements() ? JSObject::kAllowSmiOnlyElements : JSObject::kDontAllowSmiOnlyElements; return obj->SetFastElementsCapacityAndLength(capacity, length, set_capacity_mode); } protected: friend class FastElementsAccessor<FastObjectElementsAccessor, ElementsKindTraits<FAST_ELEMENTS>, kPointerSize>; virtual MaybeObject* Delete(JSObject* obj, uint32_t key, JSReceiver::DeleteMode mode) { return DeleteCommon(obj, key); } }; class FastDoubleElementsAccessor : public FastElementsAccessor<FastDoubleElementsAccessor, ElementsKindTraits<FAST_DOUBLE_ELEMENTS>, kDoubleSize> { public: explicit FastDoubleElementsAccessor(const char* name) : FastElementsAccessor<FastDoubleElementsAccessor, ElementsKindTraits<FAST_DOUBLE_ELEMENTS>, kDoubleSize>(name) {} static MaybeObject* SetFastElementsCapacityAndLength(JSObject* obj, uint32_t capacity, uint32_t length) { return obj->SetFastDoubleElementsCapacityAndLength(capacity, length); } protected: friend class ElementsAccessorBase<FastDoubleElementsAccessor, ElementsKindTraits<FAST_DOUBLE_ELEMENTS> >; friend class FastElementsAccessor<FastDoubleElementsAccessor, ElementsKindTraits<FAST_DOUBLE_ELEMENTS>, kDoubleSize>; static MaybeObject* CopyElementsImpl(FixedArrayBase* from, uint32_t from_start, FixedArrayBase* to, ElementsKind to_kind, uint32_t to_start, int copy_size) { switch (to_kind) { case FAST_SMI_ONLY_ELEMENTS: case FAST_ELEMENTS: return CopyDoubleToObjectElements( FixedDoubleArray::cast(from), from_start, FixedArray::cast(to), to_kind, to_start, copy_size); case FAST_DOUBLE_ELEMENTS: CopyDoubleToDoubleElements(FixedDoubleArray::cast(from), from_start, FixedDoubleArray::cast(to), to_start, copy_size); return from; default: UNREACHABLE(); } return to->GetHeap()->undefined_value(); } virtual MaybeObject* Delete(JSObject* obj, uint32_t key, JSReceiver::DeleteMode mode) { int length = obj->IsJSArray() ? Smi::cast(JSArray::cast(obj)->length())->value() : FixedDoubleArray::cast(obj->elements())->length(); if (key < static_cast<uint32_t>(length)) { FixedDoubleArray::cast(obj->elements())->set_the_hole(key); } return obj->GetHeap()->true_value(); } static bool HasElementImpl(Object* receiver, JSObject* holder, uint32_t key, FixedDoubleArray* backing_store) { return key < static_cast<uint32_t>(backing_store->length()) && !backing_store->is_the_hole(key); } }; // Super class for all external element arrays. template<typename ExternalElementsAccessorSubclass, ElementsKind Kind> class ExternalElementsAccessor : public ElementsAccessorBase<ExternalElementsAccessorSubclass, ElementsKindTraits<Kind> > { public: explicit ExternalElementsAccessor(const char* name) : ElementsAccessorBase<ExternalElementsAccessorSubclass, ElementsKindTraits<Kind> >(name) {} protected: typedef typename ElementsKindTraits<Kind>::BackingStore BackingStore; friend class ElementsAccessorBase<ExternalElementsAccessorSubclass, ElementsKindTraits<Kind> >; static MaybeObject* GetImpl(Object* receiver, JSObject* obj, uint32_t key, BackingStore* backing_store) { return key < ExternalElementsAccessorSubclass::GetCapacityImpl(backing_store) ? backing_store->get(key) : backing_store->GetHeap()->undefined_value(); } static MaybeObject* SetLengthImpl(JSObject* obj, Object* length, BackingStore* backing_store) { // External arrays do not support changing their length. UNREACHABLE(); return obj; } virtual MaybeObject* Delete(JSObject* obj, uint32_t key, JSReceiver::DeleteMode mode) { // External arrays always ignore deletes. return obj->GetHeap()->true_value(); } static bool HasElementImpl(Object* receiver, JSObject* holder, uint32_t key, BackingStore* backing_store) { uint32_t capacity = ExternalElementsAccessorSubclass::GetCapacityImpl(backing_store); return key < capacity; } }; class ExternalByteElementsAccessor : public ExternalElementsAccessor<ExternalByteElementsAccessor, EXTERNAL_BYTE_ELEMENTS> { public: explicit ExternalByteElementsAccessor(const char* name) : ExternalElementsAccessor<ExternalByteElementsAccessor, EXTERNAL_BYTE_ELEMENTS>(name) {} }; class ExternalUnsignedByteElementsAccessor : public ExternalElementsAccessor<ExternalUnsignedByteElementsAccessor, EXTERNAL_UNSIGNED_BYTE_ELEMENTS> { public: explicit ExternalUnsignedByteElementsAccessor(const char* name) : ExternalElementsAccessor<ExternalUnsignedByteElementsAccessor, EXTERNAL_UNSIGNED_BYTE_ELEMENTS>(name) {} }; class ExternalShortElementsAccessor : public ExternalElementsAccessor<ExternalShortElementsAccessor, EXTERNAL_SHORT_ELEMENTS> { public: explicit ExternalShortElementsAccessor(const char* name) : ExternalElementsAccessor<ExternalShortElementsAccessor, EXTERNAL_SHORT_ELEMENTS>(name) {} }; class ExternalUnsignedShortElementsAccessor : public ExternalElementsAccessor<ExternalUnsignedShortElementsAccessor, EXTERNAL_UNSIGNED_SHORT_ELEMENTS> { public: explicit ExternalUnsignedShortElementsAccessor(const char* name) : ExternalElementsAccessor<ExternalUnsignedShortElementsAccessor, EXTERNAL_UNSIGNED_SHORT_ELEMENTS>(name) {} }; class ExternalIntElementsAccessor : public ExternalElementsAccessor<ExternalIntElementsAccessor, EXTERNAL_INT_ELEMENTS> { public: explicit ExternalIntElementsAccessor(const char* name) : ExternalElementsAccessor<ExternalIntElementsAccessor, EXTERNAL_INT_ELEMENTS>(name) {} }; class ExternalUnsignedIntElementsAccessor : public ExternalElementsAccessor<ExternalUnsignedIntElementsAccessor, EXTERNAL_UNSIGNED_INT_ELEMENTS> { public: explicit ExternalUnsignedIntElementsAccessor(const char* name) : ExternalElementsAccessor<ExternalUnsignedIntElementsAccessor, EXTERNAL_UNSIGNED_INT_ELEMENTS>(name) {} }; class ExternalFloatElementsAccessor : public ExternalElementsAccessor<ExternalFloatElementsAccessor, EXTERNAL_FLOAT_ELEMENTS> { public: explicit ExternalFloatElementsAccessor(const char* name) : ExternalElementsAccessor<ExternalFloatElementsAccessor, EXTERNAL_FLOAT_ELEMENTS>(name) {} }; class ExternalDoubleElementsAccessor : public ExternalElementsAccessor<ExternalDoubleElementsAccessor, EXTERNAL_DOUBLE_ELEMENTS> { public: explicit ExternalDoubleElementsAccessor(const char* name) : ExternalElementsAccessor<ExternalDoubleElementsAccessor, EXTERNAL_DOUBLE_ELEMENTS>(name) {} }; class PixelElementsAccessor : public ExternalElementsAccessor<PixelElementsAccessor, EXTERNAL_PIXEL_ELEMENTS> { public: explicit PixelElementsAccessor(const char* name) : ExternalElementsAccessor<PixelElementsAccessor, EXTERNAL_PIXEL_ELEMENTS>(name) {} }; class DictionaryElementsAccessor : public ElementsAccessorBase<DictionaryElementsAccessor, ElementsKindTraits<DICTIONARY_ELEMENTS> > { public: explicit DictionaryElementsAccessor(const char* name) : ElementsAccessorBase<DictionaryElementsAccessor, ElementsKindTraits<DICTIONARY_ELEMENTS> >(name) {} // Adjusts the length of the dictionary backing store and returns the new // length according to ES5 section 15.4.5.2 behavior. static MaybeObject* SetLengthWithoutNormalize(SeededNumberDictionary* dict, JSArray* array, Object* length_object, uint32_t length) { if (length == 0) { // If the length of a slow array is reset to zero, we clear // the array and flush backing storage. This has the added // benefit that the array returns to fast mode. Object* obj; MaybeObject* maybe_obj = array->ResetElements(); if (!maybe_obj->ToObject(&obj)) return maybe_obj; } else { uint32_t new_length = length; uint32_t old_length = static_cast<uint32_t>(array->length()->Number()); if (new_length < old_length) { // Find last non-deletable element in range of elements to be // deleted and adjust range accordingly. Heap* heap = array->GetHeap(); int capacity = dict->Capacity(); for (int i = 0; i < capacity; i++) { Object* key = dict->KeyAt(i); if (key->IsNumber()) { uint32_t number = static_cast<uint32_t>(key->Number()); if (new_length <= number && number < old_length) { PropertyDetails details = dict->DetailsAt(i); if (details.IsDontDelete()) new_length = number + 1; } } } if (new_length != length) { MaybeObject* maybe_object = heap->NumberFromUint32(new_length); if (!maybe_object->To(&length_object)) return maybe_object; } // Remove elements that should be deleted. int removed_entries = 0; Object* the_hole_value = heap->the_hole_value(); for (int i = 0; i < capacity; i++) { Object* key = dict->KeyAt(i); if (key->IsNumber()) { uint32_t number = static_cast<uint32_t>(key->Number()); if (new_length <= number && number < old_length) { dict->SetEntry(i, the_hole_value, the_hole_value); removed_entries++; } } } // Update the number of elements. dict->ElementsRemoved(removed_entries); } } return length_object; } static MaybeObject* DeleteCommon(JSObject* obj, uint32_t key, JSReceiver::DeleteMode mode) { Isolate* isolate = obj->GetIsolate(); Heap* heap = isolate->heap(); FixedArray* backing_store = FixedArray::cast(obj->elements()); bool is_arguments = (obj->GetElementsKind() == NON_STRICT_ARGUMENTS_ELEMENTS); if (is_arguments) { backing_store = FixedArray::cast(backing_store->get(1)); } SeededNumberDictionary* dictionary = SeededNumberDictionary::cast(backing_store); int entry = dictionary->FindEntry(key); if (entry != SeededNumberDictionary::kNotFound) { Object* result = dictionary->DeleteProperty(entry, mode); if (result == heap->true_value()) { MaybeObject* maybe_elements = dictionary->Shrink(key); FixedArray* new_elements = NULL; if (!maybe_elements->To(&new_elements)) { return maybe_elements; } if (is_arguments) { FixedArray::cast(obj->elements())->set(1, new_elements); } else { obj->set_elements(new_elements); } } if (mode == JSObject::STRICT_DELETION && result == heap->false_value()) { // In strict mode, attempting to delete a non-configurable property // throws an exception. HandleScope scope(isolate); Handle<Object> holder(obj); Handle<Object> name = isolate->factory()->NewNumberFromUint(key); Handle<Object> args[2] = { name, holder }; Handle<Object> error = isolate->factory()->NewTypeError("strict_delete_property", HandleVector(args, 2)); return isolate->Throw(*error); } } return heap->true_value(); } static MaybeObject* CopyElementsImpl(FixedArrayBase* from, uint32_t from_start, FixedArrayBase* to, ElementsKind to_kind, uint32_t to_start, int copy_size) { switch (to_kind) { case FAST_SMI_ONLY_ELEMENTS: case FAST_ELEMENTS: CopyDictionaryToObjectElements( SeededNumberDictionary::cast(from), from_start, FixedArray::cast(to), to_kind, to_start, copy_size); return from; case FAST_DOUBLE_ELEMENTS: CopyDictionaryToDoubleElements( SeededNumberDictionary::cast(from), from_start, FixedDoubleArray::cast(to), to_start, copy_size); return from; default: UNREACHABLE(); } return to->GetHeap()->undefined_value(); } protected: friend class ElementsAccessorBase<DictionaryElementsAccessor, ElementsKindTraits<DICTIONARY_ELEMENTS> >; virtual MaybeObject* Delete(JSObject* obj, uint32_t key, JSReceiver::DeleteMode mode) { return DeleteCommon(obj, key, mode); } static MaybeObject* GetImpl(Object* receiver, JSObject* obj, uint32_t key, SeededNumberDictionary* backing_store) { int entry = backing_store->FindEntry(key); if (entry != SeededNumberDictionary::kNotFound) { Object* element = backing_store->ValueAt(entry); PropertyDetails details = backing_store->DetailsAt(entry); if (details.type() == CALLBACKS) { return obj->GetElementWithCallback(receiver, element, key, obj); } else { return element; } } return obj->GetHeap()->the_hole_value(); } static bool HasElementImpl(Object* receiver, JSObject* holder, uint32_t key, SeededNumberDictionary* backing_store) { return backing_store->FindEntry(key) != SeededNumberDictionary::kNotFound; } static uint32_t GetKeyForIndexImpl(SeededNumberDictionary* dict, uint32_t index) { Object* key = dict->KeyAt(index); return Smi::cast(key)->value(); } }; class NonStrictArgumentsElementsAccessor : public ElementsAccessorBase< NonStrictArgumentsElementsAccessor, ElementsKindTraits<NON_STRICT_ARGUMENTS_ELEMENTS> > { public: explicit NonStrictArgumentsElementsAccessor(const char* name) : ElementsAccessorBase< NonStrictArgumentsElementsAccessor, ElementsKindTraits<NON_STRICT_ARGUMENTS_ELEMENTS> >(name) {} protected: friend class ElementsAccessorBase< NonStrictArgumentsElementsAccessor, ElementsKindTraits<NON_STRICT_ARGUMENTS_ELEMENTS> >; static MaybeObject* GetImpl(Object* receiver, JSObject* obj, uint32_t key, FixedArray* parameter_map) { Object* probe = GetParameterMapArg(obj, parameter_map, key); if (!probe->IsTheHole()) { Context* context = Context::cast(parameter_map->get(0)); int context_index = Smi::cast(probe)->value(); ASSERT(!context->get(context_index)->IsTheHole()); return context->get(context_index); } else { // Object is not mapped, defer to the arguments. FixedArray* arguments = FixedArray::cast(parameter_map->get(1)); MaybeObject* maybe_result = ElementsAccessor::ForArray(arguments)->Get( receiver, obj, key, arguments); Object* result; if (!maybe_result->ToObject(&result)) return maybe_result; // Elements of the arguments object in slow mode might be slow aliases. if (result->IsAliasedArgumentsEntry()) { AliasedArgumentsEntry* entry = AliasedArgumentsEntry::cast(result); Context* context = Context::cast(parameter_map->get(0)); int context_index = entry->aliased_context_slot(); ASSERT(!context->get(context_index)->IsTheHole()); return context->get(context_index); } else { return result; } } } static MaybeObject* SetLengthImpl(JSObject* obj, Object* length, FixedArray* parameter_map) { // TODO(mstarzinger): This was never implemented but will be used once we // correctly implement [[DefineOwnProperty]] on arrays. UNIMPLEMENTED(); return obj; } virtual MaybeObject* Delete(JSObject* obj, uint32_t key, JSReceiver::DeleteMode mode) { FixedArray* parameter_map = FixedArray::cast(obj->elements()); Object* probe = GetParameterMapArg(obj, parameter_map, key); if (!probe->IsTheHole()) { // TODO(kmillikin): We could check if this was the last aliased // parameter, and revert to normal elements in that case. That // would enable GC of the context. parameter_map->set_the_hole(key + 2); } else { FixedArray* arguments = FixedArray::cast(parameter_map->get(1)); if (arguments->IsDictionary()) { return DictionaryElementsAccessor::DeleteCommon(obj, key, mode); } else { return FastObjectElementsAccessor::DeleteCommon(obj, key); } } return obj->GetHeap()->true_value(); } static MaybeObject* CopyElementsImpl(FixedArrayBase* from, uint32_t from_start, FixedArrayBase* to, ElementsKind to_kind, uint32_t to_start, int copy_size) { FixedArray* parameter_map = FixedArray::cast(from); FixedArray* arguments = FixedArray::cast(parameter_map->get(1)); ElementsAccessor* accessor = ElementsAccessor::ForArray(arguments); return accessor->CopyElements(NULL, from_start, to, to_kind, to_start, copy_size, arguments); } static uint32_t GetCapacityImpl(FixedArray* parameter_map) { FixedArrayBase* arguments = FixedArrayBase::cast(parameter_map->get(1)); return Max(static_cast<uint32_t>(parameter_map->length() - 2), ForArray(arguments)->GetCapacity(arguments)); } static uint32_t GetKeyForIndexImpl(FixedArray* dict, uint32_t index) { return index; } static bool HasElementImpl(Object* receiver, JSObject* holder, uint32_t key, FixedArray* parameter_map) { Object* probe = GetParameterMapArg(holder, parameter_map, key); if (!probe->IsTheHole()) { return true; } else { FixedArrayBase* arguments = FixedArrayBase::cast(parameter_map->get(1)); ElementsAccessor* accessor = ElementsAccessor::ForArray(arguments); return !accessor->Get(receiver, holder, key, arguments)->IsTheHole(); } } private: static Object* GetParameterMapArg(JSObject* holder, FixedArray* parameter_map, uint32_t key) { uint32_t length = holder->IsJSArray() ? Smi::cast(JSArray::cast(holder)->length())->value() : parameter_map->length(); return key < (length - 2 ) ? parameter_map->get(key + 2) : parameter_map->GetHeap()->the_hole_value(); } }; ElementsAccessor* ElementsAccessor::ForArray(FixedArrayBase* array) { switch (array->map()->instance_type()) { case FIXED_ARRAY_TYPE: if (array->IsDictionary()) { return elements_accessors_[DICTIONARY_ELEMENTS]; } else { return elements_accessors_[FAST_ELEMENTS]; } case EXTERNAL_BYTE_ARRAY_TYPE: return elements_accessors_[EXTERNAL_BYTE_ELEMENTS]; case EXTERNAL_UNSIGNED_BYTE_ARRAY_TYPE: return elements_accessors_[EXTERNAL_UNSIGNED_BYTE_ELEMENTS]; case EXTERNAL_SHORT_ARRAY_TYPE: return elements_accessors_[EXTERNAL_SHORT_ELEMENTS]; case EXTERNAL_UNSIGNED_SHORT_ARRAY_TYPE: return elements_accessors_[EXTERNAL_UNSIGNED_SHORT_ELEMENTS]; case EXTERNAL_INT_ARRAY_TYPE: return elements_accessors_[EXTERNAL_INT_ELEMENTS]; case EXTERNAL_UNSIGNED_INT_ARRAY_TYPE: return elements_accessors_[EXTERNAL_UNSIGNED_INT_ELEMENTS]; case EXTERNAL_FLOAT_ARRAY_TYPE: return elements_accessors_[EXTERNAL_FLOAT_ELEMENTS]; case EXTERNAL_DOUBLE_ARRAY_TYPE: return elements_accessors_[EXTERNAL_DOUBLE_ELEMENTS]; case EXTERNAL_PIXEL_ARRAY_TYPE: return elements_accessors_[EXTERNAL_PIXEL_ELEMENTS]; default: UNREACHABLE(); return NULL; } } void ElementsAccessor::InitializeOncePerProcess() { static struct ConcreteElementsAccessors { #define ACCESSOR_STRUCT(Class, Kind, Store) Class* Kind##_handler; ELEMENTS_LIST(ACCESSOR_STRUCT) #undef ACCESSOR_STRUCT } element_accessors = { #define ACCESSOR_INIT(Class, Kind, Store) new Class(#Kind), ELEMENTS_LIST(ACCESSOR_INIT) #undef ACCESSOR_INIT }; static ElementsAccessor* accessor_array[] = { #define ACCESSOR_ARRAY(Class, Kind, Store) element_accessors.Kind##_handler, ELEMENTS_LIST(ACCESSOR_ARRAY) #undef ACCESSOR_ARRAY }; STATIC_ASSERT((sizeof(accessor_array) / sizeof(*accessor_array)) == kElementsKindCount); elements_accessors_ = accessor_array; } template <typename ElementsAccessorSubclass, typename ElementsKindTraits> MaybeObject* ElementsAccessorBase<ElementsAccessorSubclass, ElementsKindTraits>:: SetLengthImpl(JSObject* obj, Object* length, typename ElementsKindTraits::BackingStore* backing_store) { JSArray* array = JSArray::cast(obj); // Fast case: The new length fits into a Smi. MaybeObject* maybe_smi_length = length->ToSmi(); Object* smi_length = Smi::FromInt(0); if (maybe_smi_length->ToObject(&smi_length) && smi_length->IsSmi()) { const int value = Smi::cast(smi_length)->value(); if (value >= 0) { Object* new_length; MaybeObject* result = ElementsAccessorSubclass:: SetLengthWithoutNormalize(backing_store, array, smi_length, value); if (!result->ToObject(&new_length)) return result; ASSERT(new_length->IsSmi() || new_length->IsUndefined()); if (new_length->IsSmi()) { array->set_length(Smi::cast(new_length)); return array; } } else { return ThrowArrayLengthRangeError(array->GetHeap()); } } // Slow case: The new length does not fit into a Smi or conversion // to slow elements is needed for other reasons. if (length->IsNumber()) { uint32_t value; if (length->ToArrayIndex(&value)) { SeededNumberDictionary* dictionary; MaybeObject* maybe_object = array->NormalizeElements(); if (!maybe_object->To(&dictionary)) return maybe_object; Object* new_length; MaybeObject* result = DictionaryElementsAccessor:: SetLengthWithoutNormalize(dictionary, array, length, value); if (!result->ToObject(&new_length)) return result; ASSERT(new_length->IsNumber()); array->set_length(new_length); return array; } else { return ThrowArrayLengthRangeError(array->GetHeap()); } } // Fall-back case: The new length is not a number so make the array // size one and set only element to length. FixedArray* new_backing_store; MaybeObject* maybe_obj = array->GetHeap()->AllocateFixedArray(1); if (!maybe_obj->To(&new_backing_store)) return maybe_obj; new_backing_store->set(0, length); { MaybeObject* result = array->SetContent(new_backing_store); if (result->IsFailure()) return result; } return array; } } } // namespace v8::internal