Array Builtin Refactoring: Creating API methods on ElementsAccessor

src/builtins.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/api-natives.h"
 #include "src/arguments.h"
 #include "src/base/once.h"
@@ skipping 67 matching lines @@
 #ifdef DEBUG
 template <>
 void BuiltinArguments<NEEDS_CALLED_FUNCTION>::Verify() {
   // Check we have at least the receiver and the called function.
   DCHECK(Arguments::length() >= 2);
   // Make sure cast to JSFunction succeeds.
   called_function();
 }
 #endif
 
-
 #define DEF_ARG_TYPE(name, spec)                      \
   typedef BuiltinArguments<spec> name##ArgumentsType;
 BUILTIN_LIST_C(DEF_ARG_TYPE)
 #undef DEF_ARG_TYPE
 
 }  // namespace
 
 // ----------------------------------------------------------------------------
 // Support macro for defining builtins in C++.
 // ----------------------------------------------------------------------------
@@ skipping 215 matching lines @@
 
 BUILTIN(ArrayPush) {
   HandleScope scope(isolate);
   Handle<Object> receiver = args.receiver();
   MaybeHandle<FixedArrayBase> maybe_elms_obj =
       EnsureJSArrayWithWritableFastElements(isolate, receiver, &args, 1);
   Handle<FixedArrayBase> elms_obj;
   if (!maybe_elms_obj.ToHandle(&elms_obj)) {
     return CallJsBuiltin(isolate, "$arrayPush", args);
   }
-
   Handle<JSArray> array = Handle<JSArray>::cast(receiver);
   int len = Smi::cast(array->length())->value();
   int to_add = args.length() - 1;
   if (to_add > 0 && JSArray::WouldChangeReadOnlyLength(array, len + to_add)) {
     return CallJsBuiltin(isolate, "$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[0], 1, to_add,

[Jakob Kummerow, 2015/07/30 11:54:59]

If you pass in &args[1] here, you don't need the |start| parameter, right?

I'm not too happy about breaking the abstraction provided by "args" here
(regarding order and whatnot). But I don't see a good alternative.

+                                  ElementsAccessor::kDirectionReverse);
+  return Smi::FromInt(new_length);
 }
 
 
 BUILTIN(ArrayPop) {
   HandleScope scope(isolate);
   Handle<Object> receiver = args.receiver();
   MaybeHandle<FixedArrayBase> maybe_elms_obj =
       EnsureJSArrayWithWritableFastElements(isolate, receiver, NULL, 0);
   Handle<FixedArrayBase> elms_obj;
   if (!maybe_elms_obj.ToHandle(&elms_obj)) {
@@ skipping 64 matching lines @@
 
   // Set the length.
   array->set_length(Smi::FromInt(len - 1));
 
   return *first;
 }
 
 
 BUILTIN(ArrayUnshift) {
   HandleScope scope(isolate);
-  Heap* heap = isolate->heap();
   Handle<Object> receiver = args.receiver();
   MaybeHandle<FixedArrayBase> maybe_elms_obj =
       EnsureJSArrayWithWritableFastElements(isolate, receiver, &args, 1);
   Handle<FixedArrayBase> elms_obj;
   if (!maybe_elms_obj.ToHandle(&elms_obj)) {
     return CallJsBuiltin(isolate, "$arrayUnshift", args);
   }
   Handle<JSArray> array = Handle<JSArray>::cast(receiver);
   DCHECK(!array->map()->is_observed());
   if (!array->HasFastSmiOrObjectElements()) {
@@ skipping 21 matching lines @@
     ElementsKind kind = array->GetElementsKind();
     ElementsAccessor* accessor = array->GetElementsAccessor();
     accessor->CopyElements(
         elms, 0, kind, new_elms, to_add,
         ElementsAccessor::kCopyToEndAndInitializeToHole);
 
     elms = new_elms;
     array->set_elements(*elms);
   } else {
     DisallowHeapAllocation no_gc;
+    Heap* heap = isolate->heap();
     heap->MoveElements(*elms, to_add, 0, len);
   }
 
   // Add the provided values.
   DisallowHeapAllocation no_gc;
   WriteBarrierMode mode = elms->GetWriteBarrierMode(no_gc);
   for (int i = 0; i < to_add; i++) {
     elms->set(i, args[i + 1], mode);
   }
 
@@ skipping 1059 matching lines @@
 BUILTIN_LIST_C(DEFINE_BUILTIN_ACCESSOR_C)
 BUILTIN_LIST_A(DEFINE_BUILTIN_ACCESSOR_A)
 BUILTIN_LIST_H(DEFINE_BUILTIN_ACCESSOR_H)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 
 
 }  // namespace internal
 }  // namespace v8