Array Builtin Refactoring: Creating API methods on ElementsAccessor

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index 9e04aaa7cca2447d665c872db882d65f7fe36159..42ef5ecc91230fdb74dee1f71a4063af9fd705c7 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -262,7 +262,7 @@ static inline MaybeHandle<FixedArrayBase> EnsureJSArrayWithWritableFastElements(
   ElementsKind target_kind = origin_kind;
   {
     DisallowHeapAllocation no_gc;
-    int arg_count = args->length() - first_added_arg;
+    int arg_count = args_length - first_added_arg;
     Object** arguments = args->arguments() - first_added_arg - (arg_count - 1);
     for (int i = 0; i < arg_count; i++) {
       Object* arg = arguments[i];
@@ -321,104 +321,22 @@ BUILTIN(ArrayPush) {
   if (!maybe_elms_obj.ToHandle(&elms_obj)) {
     return CallJsBuiltin(isolate, "$arrayPush", args);
   }
-
+  // Fast Elements Path
+  int push_size = args.length() - 1;
   Handle<JSArray> array = Handle<JSArray>::cast(receiver);
   int len = Smi::cast(array->length())->value();
-  int to_add = args.length() - 1;
-  if (to_add > 0 && JSArray::WouldChangeReadOnlyLength(array, len + to_add)) {
+  if (push_size == 0) {
+    return Smi::FromInt(len);
+  }
+  if (push_size > 0 &&
+      JSArray::WouldChangeReadOnlyLength(array, len + push_size)) {
     return CallJsBuiltin(isolate, "$arrayPush", args);
   }
   DCHECK(!array->map()->is_observed());
-
-  ElementsKind kind = array->GetElementsKind();
-
-  if (IsFastSmiOrObjectElementsKind(kind)) {
-    Handle<FixedArray> elms = Handle<FixedArray>::cast(elms_obj);
-    if (to_add == 0) {
-      return Smi::FromInt(len);
-    }
-    // Currently fixed arrays cannot grow too big, so
-    // we should never hit this case.
-    DCHECK(to_add <= (Smi::kMaxValue - len));
-
-    int new_length = len + to_add;
-
-    if (new_length > elms->length()) {
-      // New backing storage is needed.
-      int capacity = new_length + (new_length >> 1) + 16;
-      Handle<FixedArray> new_elms =
-          isolate->factory()->NewUninitializedFixedArray(capacity);
-
-      ElementsAccessor* accessor = array->GetElementsAccessor();
-      accessor->CopyElements(
-          elms_obj, 0, kind, new_elms, 0,
-          ElementsAccessor::kCopyToEndAndInitializeToHole);
-
-      elms = new_elms;
-    }
-
-    // Add the provided values.
-    DisallowHeapAllocation no_gc;
-    WriteBarrierMode mode = elms->GetWriteBarrierMode(no_gc);
-    for (int index = 0; index < to_add; index++) {
-      elms->set(index + len, args[index + 1], mode);
-    }
-
-    if (*elms != array->elements()) {
-      array->set_elements(*elms);
-    }
-
-    // Set the length.
-    array->set_length(Smi::FromInt(new_length));
-    return Smi::FromInt(new_length);
-  } else {
-    int elms_len = elms_obj->length();
-    if (to_add == 0) {
-      return Smi::FromInt(len);
-    }
-    // Currently fixed arrays cannot grow too big, so
-    // we should never hit this case.
-    DCHECK(to_add <= (Smi::kMaxValue - len));
-
-    int new_length = len + to_add;
-
-    Handle<FixedDoubleArray> new_elms;
-
-    if (new_length > elms_len) {
-      // New backing storage is needed.
-      int capacity = new_length + (new_length >> 1) + 16;
-      // Create new backing store; since capacity > 0, we can
-      // safely cast to FixedDoubleArray.
-      new_elms = Handle<FixedDoubleArray>::cast(
-          isolate->factory()->NewFixedDoubleArray(capacity));
-
-      ElementsAccessor* accessor = array->GetElementsAccessor();
-      accessor->CopyElements(
-          elms_obj, 0, kind, new_elms, 0,
-          ElementsAccessor::kCopyToEndAndInitializeToHole);
-
-    } else {
-      // to_add is > 0 and new_length <= elms_len, so elms_obj cannot be the
-      // empty_fixed_array.
-      new_elms = Handle<FixedDoubleArray>::cast(elms_obj);
-    }
-
-    // Add the provided values.
-    DisallowHeapAllocation no_gc;
-    int index;
-    for (index = 0; index < to_add; index++) {
-      Object* arg = args[index + 1];
-      new_elms->set(index + len, arg->Number());
-    }
-
-    if (*new_elms != array->elements()) {
-      array->set_elements(*new_elms);
-    }
-
-    // Set the length.
-    array->set_length(Smi::FromInt(new_length));
-    return Smi::FromInt(new_length);
-  }
+  ElementsAccessor* accessor = array->GetElementsAccessor();
+  int new_length = accessor->Push(array, elms_obj, &args[1], push_size,
+                                  ElementsAccessor::kDirectionReverse);
+  return Smi::FromInt(new_length);
 }
 
 
@@ -503,7 +421,6 @@ BUILTIN(ArrayShift) {
 
 BUILTIN(ArrayUnshift) {
   HandleScope scope(isolate);
-  Heap* heap = isolate->heap();
   Handle<Object> receiver = args.receiver();
   MaybeHandle<FixedArrayBase> maybe_elms_obj =
       EnsureJSArrayWithWritableFastElements(isolate, receiver, &args, 1);
@@ -545,6 +462,7 @@ BUILTIN(ArrayUnshift) {
     array->set_elements(*elms);
   } else {
     DisallowHeapAllocation no_gc;
+    Heap* heap = isolate->heap();
     heap->MoveElements(*elms, to_add, 0, len);
   }