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// Copyright 2022 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.
namespace array {
macro FastPackedDoubleArrayToReversed(
implicit context: Context)(elements: FixedDoubleArray,
length: Smi): JSArray {
// 3. Let A be ? ArrayCreate(𝔽(len)).
const copy: FixedDoubleArray =
UnsafeCast<FixedDoubleArray>(AllocateFixedArray(
ElementsKind::PACKED_DOUBLE_ELEMENTS, SmiUntag(length)));
// 4. Let k be 0.
let k: Smi = 0;
// 5. Repeat, while k < len,
while (k < length) {
// a. Let from be ! ToString(𝔽(len - k - 1)).
// b. Let Pk be ! ToString(𝔽(k)).
const from = length - k - 1;
// c. Let fromValue be ? Get(O, from).
const fromValue: float64 =
elements.floats[from].Value() otherwise unreachable;
// d. Perform ! CreateDataPropertyOrThrow(A, Pk, fromValue).
StoreFixedDoubleArrayElement(copy, k, fromValue);
// e. Set k to k + 1.
++k;
}
// 6. Return A.
const map: Map = LoadJSArrayElementsMap(
ElementsKind::PACKED_DOUBLE_ELEMENTS, LoadNativeContext(context));
return NewJSArray(map, copy);
}
macro FastArrayToReversed<FromElements : type extends FixedArrayBase>(
implicit context: Context)(kind: constexpr ElementsKind,
elements: FromElements, length: Smi,
initializeArray: constexpr bool): JSArray {
// 3. Let A be ? ArrayCreate(𝔽(len)).
const copy: FixedArrayBase = AllocateFixedArray(kind, SmiUntag(length));
// Reversing HOLEY_DOUBLE_ELEMENTS array may allocate heap numbers.
// We need to initialize the array to avoid running GC with garbage values.
if (initializeArray) {
dcheck(Is<FixedArray>(copy));
FillFixedArrayWithSmiZero(
kind, UnsafeCast<FixedArray>(copy), 0, SmiUntag(length));
}
// 4. Let k be 0.
let k: Smi = 0;
// 5. Repeat, while k < len,
while (k < length) {
// a. Let from be ! ToString(𝔽(len - k - 1)).
// b. Let Pk be ! ToString(𝔽(k)).
const from = length - k - 1;
// c. Let fromValue be ? Get(O, from).
const fromValue: Object = LoadElementOrUndefined(elements, from);
// d. Perform ! CreateDataPropertyOrThrow(A, Pk, fromValue).
StoreElement<FixedArray>(copy, k, fromValue);
// e. Set k to k + 1.
++k;
}
// 6. Return A.
const map: Map = LoadJSArrayElementsMap(kind, LoadNativeContext(context));
return NewJSArray(map, copy);
}
macro TryFastArrayToReversed(implicit context: Context)(receiver: JSAny):
JSArray labels Slow {
const array: FastJSArray = Cast<FastJSArray>(receiver) otherwise Slow;
if (array.length < 1) return ArrayCreate(0);
const kind: ElementsKind = array.map.elements_kind;
if (kind == ElementsKind::PACKED_SMI_ELEMENTS) {
return FastArrayToReversed<FixedArray>(
ElementsKind::PACKED_SMI_ELEMENTS,
UnsafeCast<FixedArray>(array.elements), array.length, false);
} else if (kind == ElementsKind::PACKED_ELEMENTS) {
return FastArrayToReversed<FixedArray>(
ElementsKind::PACKED_ELEMENTS, UnsafeCast<FixedArray>(array.elements),
array.length, false);
} else if (kind == ElementsKind::PACKED_DOUBLE_ELEMENTS) {
return FastPackedDoubleArrayToReversed(
UnsafeCast<FixedDoubleArray>(array.elements), array.length);
} else {
if (!IsPrototypeInitialArrayPrototype(array.map)) goto Slow;
if (IsNoElementsProtectorCellInvalid()) goto Slow;
if (kind == ElementsKind::HOLEY_SMI_ELEMENTS ||
kind == ElementsKind::HOLEY_ELEMENTS) {
return FastArrayToReversed<FixedArray>(
ElementsKind::PACKED_ELEMENTS, UnsafeCast<FixedArray>(array.elements),
array.length, false);
} else if (kind == ElementsKind::HOLEY_DOUBLE_ELEMENTS) {
return FastArrayToReversed<FixedDoubleArray>(
ElementsKind::PACKED_ELEMENTS,
UnsafeCast<FixedDoubleArray>(array.elements), array.length, true);
}
goto Slow;
}
}
transitioning builtin GenericArrayToReversed(
implicit context: Context)(receiver: JSAny): JSAny {
// 1. Let O be ? ToObject(this value).
const object: JSReceiver = ToObject_Inline(context, receiver);
// 2. Let len be ? LengthOfArrayLike(O).
const len: Number = GetLengthProperty(object);
// 3. Let A be ? ArrayCreate(𝔽(len)).
const copy = ArrayCreate(len);
// 4. Let k be 0.
let k: Number = 0;
// 5. Repeat, while k < len,
while (k < len) {
// a. Let from be ! ToString(𝔽(len - k - 1)).
// b. Let Pk be ! ToString(𝔽(k)).
const from: Number = len - k - 1;
// c. Let fromValue be ? Get(object, from).
const fromValue = GetProperty(object, from);
// d. Perform ! CreateDataPropertyOrThrow(A, Pk, fromValue).
FastCreateDataProperty(copy, k, fromValue);
// e. Set k to k + 1.
++k;
}
// 6. Return A.
return copy;
}
// https://tc39.es/proposal-change-array-by-copy/#sec-array.prototype.toReversed
transitioning javascript builtin ArrayPrototypeToReversed(
js-implicit context: NativeContext, receiver: JSAny)(...arguments): JSAny {
try {
return TryFastArrayToReversed(receiver) otherwise Slow;
} label Slow {
return GenericArrayToReversed(receiver);
}
}
}
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