Revert of Moving ArraySplice Builtin to ElementsAccessor

src/elements.cc

Index: src/elements.cc
diff --git a/src/elements.cc b/src/elements.cc
index 0eee6f520153ca650fedde7269a36148d2939236..3e80d5570b90e46e9de434d8c9f79abaa104721a 100644
--- a/src/elements.cc
+++ b/src/elements.cc
@@ -115,6 +115,7 @@
                   Object);
 }
 
+
 static void CopyObjectToObjectElements(FixedArrayBase* from_base,
                                        ElementsKind from_kind,
                                        uint32_t from_start,
@@ -585,23 +586,6 @@
     return 0;
   }
 
-  virtual Handle<JSArray> Splice(Handle<JSArray> receiver,
-                                 Handle<FixedArrayBase> backing_store,
-                                 uint32_t start, uint32_t delete_count,
-                                 Arguments args, uint32_t add_count) {
-    return ElementsAccessorSubclass::SpliceImpl(receiver, backing_store, start,
-                                                delete_count, args, add_count);
-  }
-
-  static Handle<JSArray> SpliceImpl(Handle<JSArray> receiver,
-                                    Handle<FixedArrayBase> backing_store,
-                                    uint32_t start, uint32_t delete_count,
-                                    Arguments args, uint32_t add_count) {
-    UNREACHABLE();
-    return Handle<JSArray>();
-  }
-
-
   virtual void SetLength(Handle<JSArray> array, uint32_t length) final {
     ElementsAccessorSubclass::SetLengthImpl(array, length,
                                             handle(array->elements()));
@@ -613,31 +597,23 @@
   static Handle<FixedArrayBase> ConvertElementsWithCapacity(
       Handle<JSObject> object, Handle<FixedArrayBase> old_elements,
       ElementsKind from_kind, uint32_t capacity) {
-    return ConvertElementsWithCapacity(
-        object, old_elements, from_kind, capacity,
+    Isolate* isolate = object->GetIsolate();
+    Handle<FixedArrayBase> elements;
+    if (IsFastDoubleElementsKind(kind())) {
+      elements = isolate->factory()->NewFixedDoubleArray(capacity);
+    } else {
+      elements = isolate->factory()->NewUninitializedFixedArray(capacity);
+    }
+
+    int packed = kPackedSizeNotKnown;
+    if (IsFastPackedElementsKind(from_kind) && object->IsJSArray()) {
+      packed = Smi::cast(JSArray::cast(*object)->length())->value();
+    }
+
+    ElementsAccessorSubclass::CopyElementsImpl(
+        *old_elements, 0, *elements, from_kind, 0, packed,
         ElementsAccessor::kCopyToEndAndInitializeToHole);
-  }
-
-  static Handle<FixedArrayBase> ConvertElementsWithCapacity(
-      Handle<JSObject> object, Handle<FixedArrayBase> old_elements,
-      ElementsKind from_kind, uint32_t capacity, int copy_size) {
-    Isolate* isolate = object->GetIsolate();
-    Handle<FixedArrayBase> new_elements;
-    if (IsFastDoubleElementsKind(kind())) {
-      new_elements = isolate->factory()->NewFixedDoubleArray(capacity);
-    } else {
-      new_elements = isolate->factory()->NewUninitializedFixedArray(capacity);
-    }
-
-    int packed_size = kPackedSizeNotKnown;
-    if (IsFastPackedElementsKind(from_kind) && object->IsJSArray()) {
-      packed_size = Smi::cast(JSArray::cast(*object)->length())->value();
-    }
-
-    ElementsAccessorSubclass::CopyElementsImpl(
-        *old_elements, 0, *new_elements, from_kind, 0, packed_size, copy_size);
-
-    return new_elements;
+    return elements;
   }
 
   static void GrowCapacityAndConvertImpl(Handle<JSObject> object,
@@ -1203,7 +1179,8 @@
           receiver, backing_store, KindTraits::Kind, capacity);
     } else {
       // push_size is > 0 and new_length <= elms_len, so backing_store cannot be
-      // the empty_fixed_array.
+      // the
+      // empty_fixed_array.
       new_elms = backing_store;
     }
 
@@ -1226,132 +1203,6 @@
     receiver->set_length(Smi::FromInt(new_length));
     return new_length;
   }
-
-  static void MoveElements(Heap* heap, Handle<FixedArrayBase> backing_store,
-                           int dst_index, int src_index, int len,
-                           int hole_start, int hole_end) {
-    UNREACHABLE();
-  }
-
-  static Handle<JSArray> SpliceImpl(Handle<JSArray> receiver,
-                                    Handle<FixedArrayBase> backing_store,
-                                    uint32_t start, uint32_t delete_count,
-                                    Arguments args, uint32_t add_count) {
-    Isolate* isolate = receiver->GetIsolate();
-    Heap* heap = isolate->heap();
-    const uint32_t len = Smi::cast(receiver->length())->value();
-    const uint32_t new_length = len - delete_count + add_count;
-
-    if (new_length == 0) {
-      receiver->set_elements(heap->empty_fixed_array());
-      receiver->set_length(Smi::FromInt(0));
-      return isolate->factory()->NewJSArrayWithElements(
-          backing_store, KindTraits::Kind, delete_count);
-    }
-
-    // construct the result array which holds the deleted elements
-    Handle<JSArray> deleted_elements = isolate->factory()->NewJSArray(
-        KindTraits::Kind, delete_count, delete_count);
-    if (delete_count > 0) {
-      DisallowHeapAllocation no_gc;
-      FastElementsAccessorSubclass::CopyElementsImpl(
-          *backing_store, start, deleted_elements->elements(), KindTraits::Kind,
-          0, kPackedSizeNotKnown, delete_count);
-    }
-
-    // delete and move elements to make space for add_count new elements
-    bool elms_changed = false;
-    if (add_count < delete_count) {
-      elms_changed = SpliceShrinkStep(backing_store, heap, start, delete_count,
-                                      add_count, len, new_length);
-    } else if (add_count > delete_count) {
-      elms_changed =
-          SpliceGrowStep(receiver, backing_store, isolate, heap, start,
-                         delete_count, add_count, len, new_length);
-    }
-
-    // Copy new Elements from args
-    if (IsFastDoubleElementsKind(KindTraits::Kind)) {
-      for (uint32_t index = start; index < start + add_count; index++) {
-        Object* arg = args[3 + index - start];
-        FastElementsAccessorSubclass::SetImpl(*backing_store, index, arg);
-      }
-    } else {
-      // FastSmiOrObjectElementsKind
-      Handle<FixedArray> elms = Handle<FixedArray>::cast(backing_store);
-      DisallowHeapAllocation no_gc;
-      WriteBarrierMode mode = elms->GetWriteBarrierMode(no_gc);
-      for (uint32_t index = start; index < start + add_count; index++) {
-        elms->set(index, args[3 + index - start], mode);
-      }
-    }
-
-    if (elms_changed) {
-      receiver->set_elements(*backing_store);
-    }
-    receiver->set_length(Smi::FromInt(new_length));
-    return deleted_elements;
-  }
-
- private:
-  static bool SpliceShrinkStep(Handle<FixedArrayBase>& backing_store,
-                               Heap* heap, uint32_t start,
-                               uint32_t delete_count, uint32_t add_count,
-                               uint32_t len, uint32_t new_length) {
-    const int move_left_count = len - delete_count - start;
-    const int move_left_dst_index = start + add_count;
-    const bool left_trim_array = heap->CanMoveObjectStart(*backing_store) &&
-                                 (move_left_dst_index < move_left_count);
-    if (left_trim_array) {
-      const int delta = delete_count - add_count;
-      // shift from before the insertion point to the right
-      FastElementsAccessorSubclass::MoveElements(heap, backing_store, delta, 0,
-                                                 start, 0, 0);
-      backing_store = handle(heap->LeftTrimFixedArray(*backing_store, delta));
-      return true;
-    } else {
-      // No left-trim needed or possible (in this case we left-move and store
-      // the hole)
-      FastElementsAccessorSubclass::MoveElements(
-          heap, backing_store, move_left_dst_index, start + delete_count,
-          move_left_count, new_length, len);
-    }
-    return false;
-  }
-
-
-  static bool SpliceGrowStep(Handle<JSArray> receiver,
-                             Handle<FixedArrayBase>& backing_store,
-                             Isolate* isolate, Heap* heap, uint32_t start,
-                             uint32_t delete_count, uint32_t add_count,
-                             uint32_t len, uint32_t new_length) {
-    // Currently fixed arrays cannot grow too big, so
-    // we should never hit this case.
-    DCHECK((add_count - delete_count) <= (Smi::kMaxValue - len));
-    // Check if backing_store needs to grow.
-    if (new_length > static_cast<uint32_t>(backing_store->length())) {
-      // New backing storage is needed.
-      int capacity = new_length + (new_length >> 1) + 16;
-      // partially copy all elements up to start
-      Handle<FixedArrayBase> new_elms =
-          FastElementsAccessorSubclass::ConvertElementsWithCapacity(
-              receiver, backing_store, KindTraits::Kind, capacity, start);
-      // Copy the trailing elements after start + delete_count
-      FastElementsAccessorSubclass::CopyElementsImpl(
-          *backing_store, start + delete_count, *new_elms, KindTraits::Kind,
-          start + add_count, kPackedSizeNotKnown,
-          ElementsAccessor::kCopyToEndAndInitializeToHole);
-
-      backing_store = new_elms;
-      return true;
-    } else {
-      DisallowHeapAllocation no_gc;
-      FastElementsAccessorSubclass::MoveElements(
-          heap, backing_store, start + add_count, start + delete_count,
-          (len - delete_count - start), 0, 0);
-    }
-    return false;
-  }
 };
 
 
@@ -1368,18 +1219,6 @@
     uint32_t index = FastElementsAccessorSubclass::GetIndexForEntryImpl(
         backing_store, entry);
     return backing_store->get(index);
-  }
-
-  static void MoveElements(Heap* heap, Handle<FixedArrayBase> backing_store,
-                           int dst_index, int src_index, int len,
-                           int hole_start, int hole_end) {
-    if (len == 0) return;
-    Handle<FixedArray> dst_elms = Handle<FixedArray>::cast(backing_store);
-    DisallowHeapAllocation no_gc;
-    heap->MoveElements(*dst_elms, dst_index, src_index, len);
-    if (hole_start != hole_end) {
-      dst_elms->FillWithHoles(hole_start, hole_end);
-    }
   }
 
   // NOTE: this method violates the handlified function signature convention:
@@ -1481,19 +1320,6 @@
   explicit FastDoubleElementsAccessor(const char* name)
       : FastElementsAccessor<FastElementsAccessorSubclass,
                              KindTraits>(name) {}
-
-  static void MoveElements(Heap* heap, Handle<FixedArrayBase> backing_store,
-                           int dst_index, int src_index, int len,
-                           int hole_start, int hole_end) {
-    if (len == 0) return;
-    Handle<FixedDoubleArray> dst_elms =
-        Handle<FixedDoubleArray>::cast(backing_store);
-    MemMove(dst_elms->data_start() + dst_index,
-            dst_elms->data_start() + src_index, len * kDoubleSize);
-    if (hole_start != hole_end) {
-      dst_elms->FillWithHoles(hole_start, hole_end);
-    }
-  }
 
   static void CopyElementsImpl(FixedArrayBase* from, uint32_t from_start,
                                FixedArrayBase* to, ElementsKind from_kind,