elements.cc cleanup
Reuse code for copying arguments and pushing/shifting elements. BUG= Review URL: https://codereview.chromium.org/1346013005 Cr-Commit-Position: refs/heads/master@{#30825}
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cbruni
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061e2a9b2b
300
src/elements.cc
300
src/elements.cc
@ -51,6 +51,8 @@ namespace {
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static const int kPackedSizeNotKnown = -1;
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enum Where { AT_START, AT_END };
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// First argument in list is the accessor class, the second argument is the
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// accessor ElementsKind, and the third is the backing store class. Use the
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@ -1274,119 +1276,28 @@ class FastElementsAccessor
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static Handle<Object> PopImpl(Handle<JSArray> receiver,
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Handle<FixedArrayBase> backing_store) {
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uint32_t len =
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static_cast<uint32_t>(Smi::cast(receiver->length())->value());
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DCHECK(len > 0);
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uint32_t new_length = len - 1;
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Handle<Object> result =
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FastElementsAccessorSubclass::GetImpl(backing_store, new_length);
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FastElementsAccessorSubclass::SetLengthImpl(receiver, new_length,
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backing_store);
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if (IsHoleyElementsKind(KindTraits::Kind) && result->IsTheHole()) {
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return receiver->GetIsolate()->factory()->undefined_value();
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}
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return result;
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return FastElementsAccessorSubclass::RemoveElement(receiver, backing_store,
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AT_END);
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}
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static Handle<Object> ShiftImpl(Handle<JSArray> receiver,
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Handle<FixedArrayBase> backing_store) {
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uint32_t len =
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static_cast<uint32_t>(Smi::cast(receiver->length())->value());
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Isolate* isolate = receiver->GetIsolate();
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DCHECK(len > 0);
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int new_length = len - 1;
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Handle<Object> result =
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FastElementsAccessorSubclass::GetImpl(backing_store, 0);
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Heap* heap = isolate->heap();
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if (heap->CanMoveObjectStart(*backing_store)) {
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receiver->set_elements(heap->LeftTrimFixedArray(*backing_store, 1));
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} else {
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FastElementsAccessorSubclass::MoveElements(heap, backing_store, 0, 1,
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new_length, 0, 0);
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}
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FastElementsAccessorSubclass::SetLengthImpl(receiver, new_length,
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backing_store);
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if (IsHoleyElementsKind(KindTraits::Kind) && result->IsTheHole()) {
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result = receiver->GetIsolate()->factory()->undefined_value();
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}
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return result;
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return FastElementsAccessorSubclass::RemoveElement(receiver, backing_store,
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AT_START);
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}
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static uint32_t PushImpl(Handle<JSArray> receiver,
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Handle<FixedArrayBase> backing_store,
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Arguments* args, uint32_t push_size) {
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uint32_t len = Smi::cast(receiver->length())->value();
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DCHECK(push_size > 0);
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uint32_t elms_len = backing_store->length();
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// Currently fixed arrays cannot grow too big, so
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// we should never hit this case.
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DCHECK(push_size <= static_cast<uint32_t>(Smi::kMaxValue - len));
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uint32_t new_length = len + push_size;
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if (new_length > elms_len) {
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// New backing storage is needed.
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uint32_t capacity = new_length + (new_length >> 1) + 16;
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backing_store = FastElementsAccessorSubclass::ConvertElementsWithCapacity(
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receiver, backing_store, KindTraits::Kind, capacity);
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receiver->set_elements(*backing_store);
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}
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// Add the provided values.
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DisallowHeapAllocation no_gc;
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FixedArrayBase* raw_backing_store = *backing_store;
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WriteBarrierMode mode = raw_backing_store->GetWriteBarrierMode(no_gc);
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for (uint32_t index = 0; index < push_size; index++) {
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Object* object = (*args)[index + 1];
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FastElementsAccessorSubclass::SetImpl(raw_backing_store, index + len,
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object, mode);
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}
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DCHECK(*backing_store == receiver->elements());
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// Set the length.
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receiver->set_length(Smi::FromInt(new_length));
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return new_length;
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return FastElementsAccessorSubclass::AddArguments(receiver, backing_store,
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args, push_size, AT_END);
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}
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static uint32_t UnshiftImpl(Handle<JSArray> receiver,
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Handle<FixedArrayBase> backing_store,
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Arguments* args, uint32_t unshift_size) {
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uint32_t len = Smi::cast(receiver->length())->value();
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DCHECK(unshift_size > 0);
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uint32_t elms_len = backing_store->length();
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// Currently fixed arrays cannot grow too big, so
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// we should never hit this case.
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DCHECK(unshift_size <= static_cast<uint32_t>(Smi::kMaxValue - len));
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uint32_t new_length = len + unshift_size;
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if (new_length > elms_len) {
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// New backing storage is needed.
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uint32_t capacity = new_length + (new_length >> 1) + 16;
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backing_store = FastElementsAccessorSubclass::ConvertElementsWithCapacity(
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receiver, backing_store, KindTraits::Kind, capacity, 0, unshift_size,
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ElementsAccessor::kCopyToEndAndInitializeToHole);
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DisallowHeapAllocation no_gc;
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receiver->set_elements(*backing_store);
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} else {
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// unshift_size is > 0 and new_length <= elms_len, so backing_store cannot
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// be the empty_fixed_array.
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DisallowHeapAllocation no_gc;
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Isolate* isolate = receiver->GetIsolate();
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FastElementsAccessorSubclass::MoveElements(isolate->heap(), backing_store,
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unshift_size, 0, len, 0, 0);
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}
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// Add the provided values.
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DisallowHeapAllocation no_gc;
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FixedArrayBase* raw_backing_store = *backing_store;
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WriteBarrierMode mode = raw_backing_store->GetWriteBarrierMode(no_gc);
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for (uint32_t index = 0; index < unshift_size; index++) {
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FastElementsAccessorSubclass::SetImpl(raw_backing_store, index,
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(*args)[index + 1], mode);
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}
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// Set the length.
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receiver->set_length(Smi::FromInt(new_length));
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return new_length;
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return FastElementsAccessorSubclass::AddArguments(
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receiver, backing_store, args, unshift_size, AT_START);
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}
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static void MoveElements(Heap* heap, Handle<FixedArrayBase> backing_store,
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@ -1418,8 +1329,8 @@ class FastElementsAccessor
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Arguments* args, uint32_t add_count) {
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Isolate* isolate = receiver->GetIsolate();
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Heap* heap = isolate->heap();
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uint32_t len = Smi::cast(receiver->length())->value();
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uint32_t new_length = len - delete_count + add_count;
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uint32_t length = Smi::cast(receiver->length())->value();
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uint32_t new_length = length - delete_count + add_count;
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if (new_length == 0) {
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receiver->set_elements(heap->empty_fixed_array());
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@ -1428,7 +1339,7 @@ class FastElementsAccessor
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backing_store, KindTraits::Kind, delete_count);
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}
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// construct the result array which holds the deleted elements
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// Construct the result array which holds the deleted elements.
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Handle<JSArray> deleted_elements = isolate->factory()->NewJSArray(
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KindTraits::Kind, delete_count, delete_count);
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if (delete_count > 0) {
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@ -1438,30 +1349,21 @@ class FastElementsAccessor
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0, kPackedSizeNotKnown, delete_count);
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}
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// delete and move elements to make space for add_count new elements
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bool elms_changed = false;
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// Delete and move elements to make space for add_count new elements.
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if (add_count < delete_count) {
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elms_changed = SpliceShrinkStep(backing_store, heap, start, delete_count,
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add_count, len, new_length);
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FastElementsAccessorSubclass::SpliceShrinkStep(backing_store, heap, start,
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delete_count, add_count,
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length, new_length);
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} else if (add_count > delete_count) {
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elms_changed =
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SpliceGrowStep(receiver, backing_store, isolate, heap, start,
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delete_count, add_count, len, new_length);
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backing_store = FastElementsAccessorSubclass::SpliceGrowStep(
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receiver, backing_store, isolate, heap, start, delete_count,
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add_count, length, new_length);
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}
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// Copy new Elements from args
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DisallowHeapAllocation no_gc;
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FixedArrayBase* raw_backing_store = *backing_store;
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WriteBarrierMode mode = raw_backing_store->GetWriteBarrierMode(no_gc);
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for (uint32_t index = 0; index < add_count; index++) {
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Object* object = (*args)[3 + index];
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FastElementsAccessorSubclass::SetImpl(raw_backing_store, index + start,
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object, mode);
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}
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// Copy over the arguments.
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FastElementsAccessorSubclass::CopyArguments(args, backing_store, add_count,
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3, start);
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if (elms_changed) {
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receiver->set_elements(*backing_store);
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}
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receiver->set_length(Smi::FromInt(new_length));
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FastElementsAccessorSubclass::TryTransitionResultArrayToPacked(
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deleted_elements);
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@ -1469,63 +1371,121 @@ class FastElementsAccessor
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}
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private:
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static bool SpliceShrinkStep(Handle<FixedArrayBase>& backing_store,
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Heap* heap, uint32_t start,
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uint32_t delete_count, uint32_t add_count,
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uint32_t len, uint32_t new_length) {
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static void SpliceShrinkStep(Handle<FixedArrayBase> backing_store, Heap* heap,
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uint32_t start, uint32_t delete_count,
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uint32_t add_count, uint32_t len,
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uint32_t new_length) {
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const int move_left_count = len - delete_count - start;
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const int move_left_dst_index = start + add_count;
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const bool left_trim_array = heap->CanMoveObjectStart(*backing_store) &&
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(move_left_dst_index < move_left_count);
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if (left_trim_array) {
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const int delta = delete_count - add_count;
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// shift from before the insertion point to the right
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FastElementsAccessorSubclass::MoveElements(heap, backing_store, delta, 0,
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start, 0, 0);
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backing_store = handle(heap->LeftTrimFixedArray(*backing_store, delta));
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return true;
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} else {
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// No left-trim needed or possible (in this case we left-move and store
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// the hole)
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FastElementsAccessorSubclass::MoveElements(
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heap, backing_store, move_left_dst_index, start + delete_count,
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move_left_count, new_length, len);
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}
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return false;
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FastElementsAccessorSubclass::MoveElements(
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heap, backing_store, move_left_dst_index, start + delete_count,
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move_left_count, new_length, len);
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}
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static bool SpliceGrowStep(Handle<JSArray> receiver,
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Handle<FixedArrayBase>& backing_store,
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Isolate* isolate, Heap* heap, uint32_t start,
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uint32_t delete_count, uint32_t add_count,
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uint32_t len, uint32_t new_length) {
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// Currently fixed arrays cannot grow too big, so
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// we should never hit this case.
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DCHECK((add_count - delete_count) <= (Smi::kMaxValue - len));
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// Check if backing_store needs to grow.
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if (new_length > static_cast<uint32_t>(backing_store->length())) {
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// New backing storage is needed.
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int capacity = new_length + (new_length >> 1) + 16;
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// partially copy all elements up to start
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Handle<FixedArrayBase> new_elms =
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FastElementsAccessorSubclass::ConvertElementsWithCapacity(
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receiver, backing_store, KindTraits::Kind, capacity, start);
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// Copy the trailing elements after start + delete_count
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FastElementsAccessorSubclass::CopyElementsImpl(
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*backing_store, start + delete_count, *new_elms, KindTraits::Kind,
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start + add_count, kPackedSizeNotKnown,
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ElementsAccessor::kCopyToEndAndInitializeToHole);
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backing_store = new_elms;
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return true;
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} else {
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DisallowHeapAllocation no_gc;
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static Handle<FixedArrayBase> SpliceGrowStep(
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Handle<JSArray> receiver, Handle<FixedArrayBase> backing_store,
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Isolate* isolate, Heap* heap, uint32_t start, uint32_t delete_count,
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uint32_t add_count, uint32_t length, uint32_t new_length) {
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// Check we do not overflow the new_length.
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DCHECK((add_count - delete_count) <= (Smi::kMaxValue - length));
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// Check if backing_store is big enough.
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if (new_length <= static_cast<uint32_t>(backing_store->length())) {
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FastElementsAccessorSubclass::MoveElements(
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heap, backing_store, start + add_count, start + delete_count,
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(len - delete_count - start), 0, 0);
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(length - delete_count - start), 0, 0);
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return backing_store;
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}
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// New backing storage is needed.
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int capacity = JSObject::NewElementsCapacity(new_length);
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// Partially copy all elements up to start.
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Handle<FixedArrayBase> new_elms =
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FastElementsAccessorSubclass::ConvertElementsWithCapacity(
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receiver, backing_store, KindTraits::Kind, capacity, start);
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// Copy the trailing elements after start + delete_count
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FastElementsAccessorSubclass::CopyElementsImpl(
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*backing_store, start + delete_count, *new_elms, KindTraits::Kind,
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start + add_count, kPackedSizeNotKnown,
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ElementsAccessor::kCopyToEndAndInitializeToHole);
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receiver->set_elements(*new_elms);
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return new_elms;
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}
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static Handle<Object> RemoveElement(Handle<JSArray> receiver,
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Handle<FixedArrayBase> backing_store,
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Where remove_position) {
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uint32_t length =
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static_cast<uint32_t>(Smi::cast(receiver->length())->value());
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Isolate* isolate = receiver->GetIsolate();
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DCHECK(length > 0);
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int new_length = length - 1;
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int remove_index = remove_position == AT_START ? 0 : new_length;
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Handle<Object> result =
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FastElementsAccessorSubclass::GetImpl(backing_store, remove_index);
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if (remove_position == AT_START) {
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Heap* heap = isolate->heap();
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FastElementsAccessorSubclass::MoveElements(heap, backing_store, 0, 1,
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new_length, 0, 0);
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}
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FastElementsAccessorSubclass::SetLengthImpl(receiver, new_length,
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backing_store);
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if (IsHoleyElementsKind(KindTraits::Kind) && result->IsTheHole()) {
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return receiver->GetIsolate()->factory()->undefined_value();
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}
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return result;
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}
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static uint32_t AddArguments(Handle<JSArray> receiver,
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Handle<FixedArrayBase> backing_store,
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Arguments* args, uint32_t add_size,
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Where remove_position) {
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uint32_t length = Smi::cast(receiver->length())->value();
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DCHECK(add_size > 0);
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uint32_t elms_len = backing_store->length();
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// Check we do not overflow the new_length.
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DCHECK(add_size <= static_cast<uint32_t>(Smi::kMaxValue - length));
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uint32_t new_length = length + add_size;
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if (new_length > elms_len) {
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// New backing storage is needed.
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uint32_t capacity = JSObject::NewElementsCapacity(new_length);
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// If we add arguments to the start we have to shift the existing objects.
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int copy_dst_index = remove_position == AT_START ? add_size : 0;
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// Copy over all objects to a new backing_store.
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backing_store = FastElementsAccessorSubclass::ConvertElementsWithCapacity(
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receiver, backing_store, KindTraits::Kind, capacity, 0,
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copy_dst_index, ElementsAccessor::kCopyToEndAndInitializeToHole);
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receiver->set_elements(*backing_store);
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} else if (remove_position == AT_START) {
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// If the backing store has enough capacity and we add elements to the
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// start we have to shift the existing objects.
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Isolate* isolate = receiver->GetIsolate();
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FastElementsAccessorSubclass::MoveElements(isolate->heap(), backing_store,
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add_size, 0, length, 0, 0);
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}
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int insertion_index = remove_position == AT_START ? 0 : length;
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// Copy the arguments to the start.
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FastElementsAccessorSubclass::CopyArguments(args, backing_store, add_size,
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1, insertion_index);
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// Set the length.
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receiver->set_length(Smi::FromInt(new_length));
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return new_length;
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}
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static void CopyArguments(Arguments* args, Handle<FixedArrayBase> dst_store,
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uint32_t copy_size, uint32_t src_index,
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uint32_t dst_index) {
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// Add the provided values.
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DisallowHeapAllocation no_gc;
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FixedArrayBase* raw_backing_store = *dst_store;
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WriteBarrierMode mode = raw_backing_store->GetWriteBarrierMode(no_gc);
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for (uint32_t i = 0; i < copy_size; i++) {
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Object* argument = (*args)[i + src_index];
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FastElementsAccessorSubclass::SetImpl(raw_backing_store, i + dst_index,
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argument, mode);
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}
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return false;
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}
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};
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