1// Copyright 2018 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include 'src/builtins/builtins-array-gen.h'
6
7namespace array {
8// Naming convention from elements.cc. We have a similar intent but implement
9// fastpaths using generics instead of using a class hierarchy for elements
10// kinds specific implementations.
11type GenericElementsAccessor extends ElementsKind;
12type FastPackedSmiElements extends ElementsKind;
13type FastPackedObjectElements extends ElementsKind;
14type FastPackedDoubleElements extends ElementsKind;
15type FastSmiOrObjectElements extends ElementsKind;
16type FastDoubleElements extends ElementsKind;
17type DictionaryElements extends ElementsKind;
18
19macro EnsureWriteableFastElements(implicit context: Context)(array: JSArray):
20    void {
21  dcheck(IsFastElementsKind(array.map.elements_kind));
22
23  const elements: FixedArrayBase = array.elements;
24  if (elements.map != kCOWMap) return;
25
26  // There are no COW *_DOUBLE_ELEMENTS arrays, so we are allowed to always
27  // extract FixedArrays and don't have to worry about FixedDoubleArrays.
28  dcheck(IsFastSmiOrTaggedElementsKind(array.map.elements_kind));
29
30  const length = Convert<intptr>(Cast<Smi>(array.length) otherwise unreachable);
31  array.elements =
32      ExtractFixedArray(UnsafeCast<FixedArray>(elements), 0, length, length);
33  dcheck(array.elements.map != kCOWMap);
34}
35
36macro LoadElementOrUndefined(implicit context: Context)(
37    a: FixedArray, i: Smi): JSAny {
38  const e = UnsafeCast<(JSAny | TheHole)>(a.objects[i]);
39  return ReplaceTheHoleWithUndefined(e);
40}
41
42macro LoadElementOrUndefined(a: FixedDoubleArray, i: Smi): NumberOrUndefined {
43  const f: float64 = a.floats[i].Value() otherwise return Undefined;
44  return AllocateHeapNumberWithValue(f);
45}
46
47macro StoreArrayHole(elements: FixedDoubleArray, k: Smi): void {
48  elements.floats[k] = kDoubleHole;
49}
50
51macro StoreArrayHole(elements: FixedArray, k: Smi): void {
52  elements.objects[k] = TheHole;
53}
54
55extern macro SetPropertyLength(implicit context: Context)(JSAny, Number): void;
56
57const kLengthDescriptorIndex:
58    constexpr int31 generates 'JSArray::kLengthDescriptorIndex';
59const kAttributesReadOnlyMask: constexpr int31
60    generates 'PropertyDetails::kAttributesReadOnlyMask';
61
62@export
63macro EnsureArrayLengthWritable(implicit context: Context)(map: Map):
64    void labels Bailout {
65  // Don't support arrays in dictionary named property mode.
66  if (IsDictionaryMap(map)) {
67    goto Bailout;
68  }
69
70  // Check whether the length property is writable. The length property is the
71  // only default named property on arrays. It's nonconfigurable, hence is
72  // guaranteed to stay the first property.
73  const descriptors: DescriptorArray = map.instance_descriptors;
74  const descriptor:&DescriptorEntry =
75      &descriptors.descriptors[kLengthDescriptorIndex];
76  dcheck(TaggedEqual(descriptor->key, LengthStringConstant()));
77  const details: Smi = UnsafeCast<Smi>(descriptor->details);
78  if ((details & kAttributesReadOnlyMask) != 0) {
79    goto Bailout;
80  }
81}
82
83macro CreateJSArrayWithElements(implicit context: Context)(array: FixedArray):
84    JSArray {
85  const nativeContext: NativeContext = LoadNativeContext(context);
86  const map: Map =
87      LoadJSArrayElementsMap(ElementsKind::PACKED_ELEMENTS, nativeContext);
88  return AllocateJSArray(map, array, array.length);
89}
90}
91