Bug 1885337 - Part 2: Implement to/from base64 methods. r=dminor

[gecko.git] / js / src / vm / TypedArrayObject.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "vm/TypedArrayObject-inl.h"
#include "vm/TypedArrayObject.h"

#include "mozilla/CheckedInt.h"
#include "mozilla/FloatingPoint.h"
#include "mozilla/IntegerTypeTraits.h"
#include "mozilla/Likely.h"
#include "mozilla/PodOperations.h"
#include "mozilla/TextUtils.h"

#include <algorithm>
#include <iterator>
#include <limits>
#include <numeric>
#include <string.h>
#include <string_view>
#if !defined(XP_WIN) && !defined(__wasi__)
#  include <sys/mman.h>
#endif
#include <type_traits>

#include "jsnum.h"
#include "jstypes.h"

#include "builtin/Array.h"
#include "builtin/DataViewObject.h"
#include "gc/Barrier.h"
#include "gc/MaybeRooted.h"
#include "jit/InlinableNatives.h"
#include "js/Conversions.h"
#include "js/experimental/TypedData.h"  // JS_GetArrayBufferViewType, JS_GetTypedArray{Length,ByteOffset,ByteLength}, JS_IsTypedArrayObject
#include "js/friend/ErrorMessages.h"    // js::GetErrorMessage, JSMSG_*
#include "js/PropertySpec.h"
#include "js/ScalarType.h"  // JS::Scalar::Type
#include "js/UniquePtr.h"
#include "js/Wrapper.h"
#include "util/DifferentialTesting.h"
#include "util/StringBuffer.h"
#include "util/Text.h"
#include "util/WindowsWrapper.h"
#include "vm/ArrayBufferObject.h"
#include "vm/FunctionFlags.h"  // js::FunctionFlags
#include "vm/GlobalObject.h"
#include "vm/JSContext.h"
#include "vm/JSObject.h"
#include "vm/PIC.h"
#include "vm/SelfHosting.h"
#include "vm/SharedMem.h"
#include "vm/Uint8Clamped.h"
#include "vm/WrapperObject.h"

#include "gc/Nursery-inl.h"
#include "vm/ArrayBufferObject-inl.h"
#include "vm/Compartment-inl.h"
#include "vm/GeckoProfiler-inl.h"
#include "vm/NativeObject-inl.h"

using namespace js;

using JS::CanonicalizeNaN;
using JS::ToInt32;
using JS::ToUint32;
using mozilla::IsAsciiDigit;

/*
 * TypedArrayObject
 *
 * The non-templated base class for the specific typed implementations.
 * This class holds all the member variables that are used by
 * the subclasses.
 */

bool TypedArrayObject::convertValue(JSContext* cx, HandleValue v,
                                    MutableHandleValue result) const {
  switch (type()) {
    case Scalar::BigInt64:
    case Scalar::BigUint64: {
      BigInt* bi = ToBigInt(cx, v);
      if (!bi) {
        return false;
      }
      result.setBigInt(bi);
      return true;
    }
    case Scalar::Int8:
    case Scalar::Uint8:
    case Scalar::Int16:
    case Scalar::Uint16:
    case Scalar::Int32:
    case Scalar::Uint32:
    case Scalar::Float32:
    case Scalar::Float64:
    case Scalar::Uint8Clamped: {
      double num;
      if (!ToNumber(cx, v, &num)) {
        return false;
      }
      result.setNumber(num);
      return true;
    }
    case Scalar::MaxTypedArrayViewType:
    case Scalar::Int64:
    case Scalar::Simd128:
      MOZ_CRASH("Unsupported TypedArray type");
  }
  MOZ_ASSERT_UNREACHABLE("Invalid scalar type");
  return false;
}

static bool IsTypedArrayObject(HandleValue v) {
  return v.isObject() && v.toObject().is<TypedArrayObject>();
}

static bool IsUint8ArrayObject(HandleValue v) {
  return IsTypedArrayObject(v) &&
         v.toObject().as<TypedArrayObject>().type() == Scalar::Uint8;
}

/* static */
bool TypedArrayObject::ensureHasBuffer(JSContext* cx,
                                       Handle<TypedArrayObject*> typedArray) {
  if (typedArray->hasBuffer()) {
    return true;
  }

  MOZ_ASSERT(typedArray->is<FixedLengthTypedArrayObject>(),
             "Resizable TypedArrays always use an ArrayBuffer");

  Rooted<FixedLengthTypedArrayObject*> tarray(
      cx, &typedArray->as<FixedLengthTypedArrayObject>());

  size_t byteLength = tarray->byteLength();

  AutoRealm ar(cx, tarray);
  Rooted<ArrayBufferObject*> buffer(
      cx, ArrayBufferObject::createZeroed(cx, tarray->byteLength()));
  if (!buffer) {
    return false;
  }

  buffer->pinLength(tarray->isLengthPinned());

  // Attaching the first view to an array buffer is infallible.
  MOZ_ALWAYS_TRUE(buffer->addView(cx, tarray));

  // tarray is not shared, because if it were it would have a buffer.
  memcpy(buffer->dataPointer(), tarray->dataPointerUnshared(), byteLength);

  // If the object is in the nursery, the buffer will be freed by the next
  // nursery GC. Free the data slot pointer if the object has no inline data.
  size_t nbytes = RoundUp(byteLength, sizeof(Value));
  Nursery& nursery = cx->nursery();
  if (tarray->isTenured() && !tarray->hasInlineElements() &&
      !nursery.isInside(tarray->elements())) {
    js_free(tarray->elements());
    RemoveCellMemory(tarray, nbytes, MemoryUse::TypedArrayElements);
  }

  tarray->setFixedSlot(TypedArrayObject::DATA_SLOT,
                       PrivateValue(buffer->dataPointer()));
  tarray->setFixedSlot(TypedArrayObject::BUFFER_SLOT, ObjectValue(*buffer));

  return true;
}

#ifdef DEBUG
void FixedLengthTypedArrayObject::assertZeroLengthArrayData() const {
  if (length() == 0 && !hasBuffer()) {
    uint8_t* end = fixedData(FixedLengthTypedArrayObject::FIXED_DATA_START);
    MOZ_ASSERT(end[0] == ZeroLengthArrayData);
  }
}
#endif

void FixedLengthTypedArrayObject::finalize(JS::GCContext* gcx, JSObject* obj) {
  MOZ_ASSERT(!IsInsideNursery(obj));
  auto* curObj = &obj->as<FixedLengthTypedArrayObject>();

  // Template objects or discarded objects (which didn't have enough room
  // for inner elements) don't have anything to free.
  if (!curObj->elementsRaw()) {
    return;
  }

  curObj->assertZeroLengthArrayData();

  // Typed arrays with a buffer object do not need to be free'd
  if (curObj->hasBuffer()) {
    return;
  }

  // Free the data slot pointer if it does not point into the old JSObject.
  if (!curObj->hasInlineElements()) {
    size_t nbytes = RoundUp(curObj->byteLength(), sizeof(Value));
    gcx->free_(obj, curObj->elements(), nbytes, MemoryUse::TypedArrayElements);
  }
}

/* static */
size_t FixedLengthTypedArrayObject::objectMoved(JSObject* obj, JSObject* old) {
  auto* newObj = &obj->as<FixedLengthTypedArrayObject>();
  const auto* oldObj = &old->as<FixedLengthTypedArrayObject>();
  MOZ_ASSERT(newObj->elementsRaw() == oldObj->elementsRaw());

  // Typed arrays with a buffer object do not need an update.
  if (oldObj->hasBuffer()) {
    return 0;
  }

  if (!IsInsideNursery(old)) {
    // Update the data slot pointer if it points to the old JSObject.
    if (oldObj->hasInlineElements()) {
      newObj->setInlineElements();
    }

    return 0;
  }

  void* buf = oldObj->elements();

  // Discarded objects (which didn't have enough room for inner elements) don't
  // have any data to move.
  if (!buf) {
    return 0;
  }

  Nursery& nursery = obj->runtimeFromMainThread()->gc.nursery();

  // Determine if we can use inline data for the target array. If this is
  // possible, the nursery will have picked an allocation size that is large
  // enough.
  size_t nbytes = oldObj->byteLength();
  bool canUseDirectForward = nbytes >= sizeof(uintptr_t);

  constexpr size_t headerSize = dataOffset() + sizeof(HeapSlot);

  gc::AllocKind allocKind = oldObj->allocKindForTenure();
  MOZ_ASSERT_IF(obj->isTenured(), obj->asTenured().getAllocKind() == allocKind);
  MOZ_ASSERT_IF(nbytes == 0,
                headerSize + sizeof(uint8_t) <= GetGCKindBytes(allocKind));

  if (nursery.isInside(buf) &&
      headerSize + nbytes <= GetGCKindBytes(allocKind)) {
    MOZ_ASSERT(oldObj->hasInlineElements());
#ifdef DEBUG
    if (nbytes == 0) {
      uint8_t* output =
          newObj->fixedData(FixedLengthTypedArrayObject::FIXED_DATA_START);
      output[0] = ZeroLengthArrayData;
    }
#endif
    newObj->setInlineElements();
    mozilla::PodCopy(newObj->elements(), oldObj->elements(), nbytes);

    // Set a forwarding pointer for the element buffers in case they were
    // preserved on the stack by Ion.
    nursery.setForwardingPointerWhileTenuring(
        oldObj->elements(), newObj->elements(), canUseDirectForward);

    return 0;
  }

  // Non-inline allocations are rounded up.
  nbytes = RoundUp(nbytes, sizeof(Value));

  Nursery::WasBufferMoved result = nursery.maybeMoveBufferOnPromotion(
      &buf, newObj, nbytes, MemoryUse::TypedArrayElements,
      ArrayBufferContentsArena);
  if (result == Nursery::BufferMoved) {
    newObj->setReservedSlot(DATA_SLOT, PrivateValue(buf));

    // Set a forwarding pointer for the element buffers in case they were
    // preserved on the stack by Ion.
    nursery.setForwardingPointerWhileTenuring(
        oldObj->elements(), newObj->elements(), canUseDirectForward);

    return nbytes;
  }

  return 0;
}

bool FixedLengthTypedArrayObject::hasInlineElements() const {
  return elements() ==
             this->fixedData(FixedLengthTypedArrayObject::FIXED_DATA_START) &&
         byteLength() <= FixedLengthTypedArrayObject::INLINE_BUFFER_LIMIT;
}

void FixedLengthTypedArrayObject::setInlineElements() {
  char* dataSlot = reinterpret_cast<char*>(this) + dataOffset();
  *reinterpret_cast<void**>(dataSlot) =
      this->fixedData(FixedLengthTypedArrayObject::FIXED_DATA_START);
}

/* Helper clamped uint8_t type */

uint32_t js::ClampDoubleToUint8(const double x) {
  // Not < so that NaN coerces to 0
  if (!(x >= 0)) {
    return 0;
  }

  if (x > 255) {
    return 255;
  }

  double toTruncate = x + 0.5;
  uint8_t y = uint8_t(toTruncate);

  /*
   * now val is rounded to nearest, ties rounded up.  We want
   * rounded to nearest ties to even, so check whether we had a
   * tie.
   */
  if (y == toTruncate) {
    /*
     * It was a tie (since adding 0.5 gave us the exact integer
     * we want).  Since we rounded up, we either already have an
     * even number or we have an odd number but the number we
     * want is one less.  So just unconditionally masking out the
     * ones bit should do the trick to get us the value we
     * want.
     */
    return y & ~1;
  }

  return y;
}

static void ReportOutOfBounds(JSContext* cx, TypedArrayObject* typedArray) {
  if (typedArray->hasDetachedBuffer()) {
    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                              JSMSG_TYPED_ARRAY_DETACHED);
  } else {
    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                              JSMSG_TYPED_ARRAY_RESIZED_BOUNDS);
  }
}

namespace {

template <class TypedArrayType>
static TypedArrayType* NewTypedArrayObject(JSContext* cx, const JSClass* clasp,
                                           HandleObject proto,
                                           gc::AllocKind allocKind,
                                           gc::Heap heap) {
  MOZ_ASSERT(proto);

  MOZ_ASSERT(CanChangeToBackgroundAllocKind(allocKind, clasp));
  allocKind = ForegroundToBackgroundAllocKind(allocKind);

  static_assert(std::is_same_v<TypedArrayType, FixedLengthTypedArrayObject> ||
                std::is_same_v<TypedArrayType, ResizableTypedArrayObject>);

  // Fixed length typed arrays can store data inline so we only use fixed slots
  // to cover the reserved slots, ignoring the AllocKind.
  MOZ_ASSERT(ClassCanHaveFixedData(clasp));
  constexpr size_t nfixed = TypedArrayType::RESERVED_SLOTS;
  static_assert(nfixed <= NativeObject::MAX_FIXED_SLOTS);
  static_assert(!std::is_same_v<TypedArrayType, FixedLengthTypedArrayObject> ||
                nfixed == FixedLengthTypedArrayObject::FIXED_DATA_START);

  Rooted<SharedShape*> shape(
      cx,
      SharedShape::getInitialShape(cx, clasp, cx->realm(), AsTaggedProto(proto),
                                   nfixed, ObjectFlags()));
  if (!shape) {
    return nullptr;
  }

  return NativeObject::create<TypedArrayType>(cx, allocKind, heap, shape);
}

template <typename NativeType>
class FixedLengthTypedArrayObjectTemplate;

template <typename NativeType>
class ResizableTypedArrayObjectTemplate;

template <typename NativeType>
class TypedArrayObjectTemplate {
  friend class js::TypedArrayObject;

  using FixedLengthTypedArray = FixedLengthTypedArrayObjectTemplate<NativeType>;
  using ResizableTypedArray = ResizableTypedArrayObjectTemplate<NativeType>;
  using AutoLength = ArrayBufferViewObject::AutoLength;

  static constexpr auto ByteLengthLimit = TypedArrayObject::ByteLengthLimit;
  static constexpr auto INLINE_BUFFER_LIMIT =
      FixedLengthTypedArrayObject::INLINE_BUFFER_LIMIT;

 public:
  static constexpr Scalar::Type ArrayTypeID() {
    return TypeIDOfType<NativeType>::id;
  }
  static constexpr JSProtoKey protoKey() {
    return TypeIDOfType<NativeType>::protoKey;
  }

  static constexpr bool ArrayTypeIsUnsigned() {
    return TypeIsUnsigned<NativeType>();
  }
  static constexpr bool ArrayTypeIsFloatingPoint() {
    return TypeIsFloatingPoint<NativeType>();
  }

  static constexpr size_t BYTES_PER_ELEMENT = sizeof(NativeType);

  static JSObject* createPrototype(JSContext* cx, JSProtoKey key) {
    Handle<GlobalObject*> global = cx->global();
    RootedObject typedArrayProto(
        cx, GlobalObject::getOrCreateTypedArrayPrototype(cx, global));
    if (!typedArrayProto) {
      return nullptr;
    }

    const JSClass* clasp = TypedArrayObject::protoClassForType(ArrayTypeID());
    return GlobalObject::createBlankPrototypeInheriting(cx, clasp,
                                                        typedArrayProto);
  }

  static JSObject* createConstructor(JSContext* cx, JSProtoKey key) {
    Handle<GlobalObject*> global = cx->global();
    RootedFunction ctorProto(
        cx, GlobalObject::getOrCreateTypedArrayConstructor(cx, global));
    if (!ctorProto) {
      return nullptr;
    }

    JSFunction* fun = NewFunctionWithProto(
        cx, class_constructor, 3, FunctionFlags::NATIVE_CTOR, nullptr,
        ClassName(key, cx), ctorProto, gc::AllocKind::FUNCTION, TenuredObject);

    if (fun) {
      fun->setJitInfo(&jit::JitInfo_TypedArrayConstructor);
    }

    return fun;
  }

  static bool convertValue(JSContext* cx, HandleValue v, NativeType* result);

  static TypedArrayObject* makeTypedArrayWithTemplate(
      JSContext* cx, TypedArrayObject* templateObj, HandleObject array) {
    MOZ_ASSERT(!IsWrapper(array));
    MOZ_ASSERT(!array->is<ArrayBufferObjectMaybeShared>());

    return fromArray(cx, array);
  }

  static TypedArrayObject* makeTypedArrayWithTemplate(
      JSContext* cx, TypedArrayObject* templateObj, HandleObject arrayBuffer,
      HandleValue byteOffsetValue, HandleValue lengthValue) {
    MOZ_ASSERT(!IsWrapper(arrayBuffer));
    MOZ_ASSERT(arrayBuffer->is<ArrayBufferObjectMaybeShared>());

    uint64_t byteOffset, length;
    if (!byteOffsetAndLength(cx, byteOffsetValue, lengthValue, &byteOffset,
                             &length)) {
      return nullptr;
    }

    return fromBufferSameCompartment(
        cx, arrayBuffer.as<ArrayBufferObjectMaybeShared>(), byteOffset, length,
        nullptr);
  }

  // ES2023 draft rev cf86f1cdc28e809170733d74ea64fd0f3dd79f78
  // 23.2.5.1 TypedArray ( ...args )
  static bool class_constructor(JSContext* cx, unsigned argc, Value* vp) {
    AutoJSConstructorProfilerEntry pseudoFrame(cx, "[TypedArray]");
    CallArgs args = CallArgsFromVp(argc, vp);

    // Step 1.
    if (!ThrowIfNotConstructing(cx, args, "typed array")) {
      return false;
    }

    // Steps 2-6.
    JSObject* obj = create(cx, args);
    if (!obj) {
      return false;
    }
    args.rval().setObject(*obj);
    return true;
  }

 private:
  static JSObject* create(JSContext* cx, const CallArgs& args) {
    MOZ_ASSERT(args.isConstructing());

    // Steps 5 and 6.c.
    if (args.length() == 0 || !args[0].isObject()) {
      // Step 6.c.ii.
      uint64_t len;
      if (!ToIndex(cx, args.get(0), JSMSG_BAD_ARRAY_LENGTH, &len)) {
        return nullptr;
      }

      // Steps 5.a and 6.c.iii.
      RootedObject proto(cx);
      if (!GetPrototypeFromBuiltinConstructor(cx, args, protoKey(), &proto)) {
        return nullptr;
      }

      return fromLength(cx, len, proto);
    }

    RootedObject dataObj(cx, &args[0].toObject());

    // Step 6.b.i.
    // 23.2.5.1.1 AllocateTypedArray, step 1.
    RootedObject proto(cx);
    if (!GetPrototypeFromBuiltinConstructor(cx, args, protoKey(), &proto)) {
      return nullptr;
    }

    // Steps 6.b.ii and 6.b.iv.
    if (!UncheckedUnwrap(dataObj)->is<ArrayBufferObjectMaybeShared>()) {
      return fromArray(cx, dataObj, proto);
    }

    // Steps 6.b.iii.1-2.
    // 23.2.5.1.3 InitializeTypedArrayFromArrayBuffer, steps 2 and 4.
    uint64_t byteOffset, length;
    if (!byteOffsetAndLength(cx, args.get(1), args.get(2), &byteOffset,
                             &length)) {
      return nullptr;
    }

    // Step 6.b.iii.3.
    if (dataObj->is<ArrayBufferObjectMaybeShared>()) {
      auto buffer = dataObj.as<ArrayBufferObjectMaybeShared>();
      return fromBufferSameCompartment(cx, buffer, byteOffset, length, proto);
    }
    return fromBufferWrapped(cx, dataObj, byteOffset, length, proto);
  }

  // ES2023 draft rev cf86f1cdc28e809170733d74ea64fd0f3dd79f78
  // 23.2.5.1.3 InitializeTypedArrayFromArrayBuffer ( O, buffer, byteOffset,
  // length ) Steps 2 and 4.
  static bool byteOffsetAndLength(JSContext* cx, HandleValue byteOffsetValue,
                                  HandleValue lengthValue, uint64_t* byteOffset,
                                  uint64_t* length) {
    // Step 2.
    *byteOffset = 0;
    if (!byteOffsetValue.isUndefined()) {
      if (!ToIndex(cx, byteOffsetValue, byteOffset)) {
        return false;
      }

      // Step 7.
      if (*byteOffset % BYTES_PER_ELEMENT != 0) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                  JSMSG_TYPED_ARRAY_CONSTRUCT_OFFSET_BOUNDS,
                                  Scalar::name(ArrayTypeID()),
                                  Scalar::byteSizeString(ArrayTypeID()));
        return false;
      }
    }

    // Step 4.
    *length = UINT64_MAX;
    if (!lengthValue.isUndefined()) {
      if (!ToIndex(cx, lengthValue, length)) {
        return false;
      }
    }

    return true;
  }

  // ES2023 draft rev cf86f1cdc28e809170733d74ea64fd0f3dd79f78
  // 23.2.5.1.3 InitializeTypedArrayFromArrayBuffer ( O, buffer, byteOffset,
  // length ) Steps 5-8.
  static bool computeAndCheckLength(
      JSContext* cx, Handle<ArrayBufferObjectMaybeShared*> bufferMaybeUnwrapped,
      uint64_t byteOffset, uint64_t lengthIndex, size_t* length,
      AutoLength* autoLength) {
    MOZ_ASSERT(byteOffset % BYTES_PER_ELEMENT == 0);
    MOZ_ASSERT(byteOffset < uint64_t(DOUBLE_INTEGRAL_PRECISION_LIMIT));
    MOZ_ASSERT_IF(lengthIndex != UINT64_MAX,
                  lengthIndex < uint64_t(DOUBLE_INTEGRAL_PRECISION_LIMIT));

    // Step 5.
    if (bufferMaybeUnwrapped->isDetached()) {
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                JSMSG_TYPED_ARRAY_DETACHED);
      return false;
    }

    // Step 6.
    size_t bufferByteLength = bufferMaybeUnwrapped->byteLength();
    MOZ_ASSERT(bufferByteLength <= ByteLengthLimit);

    size_t len;
    if (lengthIndex == UINT64_MAX) {
      // Check if |byteOffset| valid.
      if (byteOffset > bufferByteLength) {
        JS_ReportErrorNumberASCII(
            cx, GetErrorMessage, nullptr,
            JSMSG_TYPED_ARRAY_CONSTRUCT_OFFSET_LENGTH_BOUNDS,
            Scalar::name(ArrayTypeID()));
        return false;
      }

      // Resizable buffers without an explicit length are auto-length.
      if (bufferMaybeUnwrapped->isResizable()) {
        *length = 0;
        *autoLength = AutoLength::Yes;
        return true;
      }

      // Steps 7.a and 7.c.
      if (bufferByteLength % BYTES_PER_ELEMENT != 0) {
        // The given byte array doesn't map exactly to
        // |BYTES_PER_ELEMENT * N|
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                  JSMSG_TYPED_ARRAY_CONSTRUCT_OFFSET_MISALIGNED,
                                  Scalar::name(ArrayTypeID()),
                                  Scalar::byteSizeString(ArrayTypeID()));
        return false;
      }

      // Step 7.b.
      size_t newByteLength = bufferByteLength - size_t(byteOffset);
      len = newByteLength / BYTES_PER_ELEMENT;
    } else {
      // Step 8.a.
      uint64_t newByteLength = lengthIndex * BYTES_PER_ELEMENT;

      // Step 8.b.
      if (byteOffset + newByteLength > bufferByteLength) {
        // |byteOffset + newByteLength| is too big for the arraybuffer
        JS_ReportErrorNumberASCII(
            cx, GetErrorMessage, nullptr,
            JSMSG_TYPED_ARRAY_CONSTRUCT_ARRAY_LENGTH_BOUNDS,
            Scalar::name(ArrayTypeID()));
        return false;
      }

      len = size_t(lengthIndex);
    }

    MOZ_ASSERT(len <= ByteLengthLimit / BYTES_PER_ELEMENT);
    *length = len;
    *autoLength = AutoLength::No;
    return true;
  }

  // ES2023 draft rev cf86f1cdc28e809170733d74ea64fd0f3dd79f78
  // 23.2.5.1.3 InitializeTypedArrayFromArrayBuffer ( O, buffer, byteOffset,
  // length ) Steps 5-13.
  static TypedArrayObject* fromBufferSameCompartment(
      JSContext* cx, Handle<ArrayBufferObjectMaybeShared*> buffer,
      uint64_t byteOffset, uint64_t lengthIndex, HandleObject proto) {
    // Steps 5-8.
    size_t length = 0;
    auto autoLength = AutoLength::No;
    if (!computeAndCheckLength(cx, buffer, byteOffset, lengthIndex, &length,
                               &autoLength)) {
      return nullptr;
    }

    if (!buffer->isResizable()) {
      // Steps 9-13.
      return FixedLengthTypedArray::makeInstance(cx, buffer, byteOffset, length,
                                                 proto);
    }

    return ResizableTypedArray::makeInstance(cx, buffer, byteOffset, length,
                                             autoLength, proto);
  }

  // Create a TypedArray object in another compartment.
  //
  // ES6 supports creating a TypedArray in global A (using global A's
  // TypedArray constructor) backed by an ArrayBuffer created in global B.
  //
  // Our TypedArrayObject implementation doesn't support a TypedArray in
  // compartment A backed by an ArrayBuffer in compartment B. So in this
  // case, we create the TypedArray in B (!) and return a cross-compartment
  // wrapper.
  //
  // Extra twist: the spec says the new TypedArray's [[Prototype]] must be
  // A's TypedArray.prototype. So even though we're creating the TypedArray
  // in B, its [[Prototype]] must be (a cross-compartment wrapper for) the
  // TypedArray.prototype in A.
  static JSObject* fromBufferWrapped(JSContext* cx, HandleObject bufobj,
                                     uint64_t byteOffset, uint64_t lengthIndex,
                                     HandleObject proto) {
    JSObject* unwrapped = CheckedUnwrapStatic(bufobj);
    if (!unwrapped) {
      ReportAccessDenied(cx);
      return nullptr;
    }

    if (!unwrapped->is<ArrayBufferObjectMaybeShared>()) {
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                JSMSG_TYPED_ARRAY_BAD_ARGS);
      return nullptr;
    }

    Rooted<ArrayBufferObjectMaybeShared*> unwrappedBuffer(cx);
    unwrappedBuffer = &unwrapped->as<ArrayBufferObjectMaybeShared>();

    size_t length = 0;
    auto autoLength = AutoLength::No;
    if (!computeAndCheckLength(cx, unwrappedBuffer, byteOffset, lengthIndex,
                               &length, &autoLength)) {
      return nullptr;
    }

    // Make sure to get the [[Prototype]] for the created typed array from
    // this compartment.
    RootedObject protoRoot(cx, proto);
    if (!protoRoot) {
      protoRoot = GlobalObject::getOrCreatePrototype(cx, protoKey());
      if (!protoRoot) {
        return nullptr;
      }
    }

    RootedObject typedArray(cx);
    {
      JSAutoRealm ar(cx, unwrappedBuffer);

      RootedObject wrappedProto(cx, protoRoot);
      if (!cx->compartment()->wrap(cx, &wrappedProto)) {
        return nullptr;
      }

      if (!unwrappedBuffer->isResizable()) {
        typedArray = FixedLengthTypedArray::makeInstance(
            cx, unwrappedBuffer, byteOffset, length, wrappedProto);
      } else {
        typedArray = ResizableTypedArray::makeInstance(
            cx, unwrappedBuffer, byteOffset, length, autoLength, wrappedProto);
      }
      if (!typedArray) {
        return nullptr;
      }
    }

    if (!cx->compartment()->wrap(cx, &typedArray)) {
      return nullptr;
    }

    return typedArray;
  }

 public:
  static JSObject* fromBuffer(JSContext* cx, HandleObject bufobj,
                              size_t byteOffset, int64_t lengthInt) {
    if (byteOffset % BYTES_PER_ELEMENT != 0) {
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                JSMSG_TYPED_ARRAY_CONSTRUCT_OFFSET_BOUNDS,
                                Scalar::name(ArrayTypeID()),
                                Scalar::byteSizeString(ArrayTypeID()));
      return nullptr;  // invalid byteOffset
    }

    uint64_t lengthIndex = lengthInt >= 0 ? uint64_t(lengthInt) : UINT64_MAX;
    if (bufobj->is<ArrayBufferObjectMaybeShared>()) {
      auto buffer = bufobj.as<ArrayBufferObjectMaybeShared>();
      return fromBufferSameCompartment(cx, buffer, byteOffset, lengthIndex,
                                       nullptr);
    }
    return fromBufferWrapped(cx, bufobj, byteOffset, lengthIndex, nullptr);
  }

  static bool maybeCreateArrayBuffer(JSContext* cx, uint64_t count,
                                     MutableHandle<ArrayBufferObject*> buffer) {
    if (count > ByteLengthLimit / BYTES_PER_ELEMENT) {
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                JSMSG_BAD_ARRAY_LENGTH);
      return false;
    }
    size_t byteLength = count * BYTES_PER_ELEMENT;

    MOZ_ASSERT(byteLength <= ByteLengthLimit);
    static_assert(INLINE_BUFFER_LIMIT % BYTES_PER_ELEMENT == 0,
                  "ArrayBuffer inline storage shouldn't waste any space");

    if (byteLength <= INLINE_BUFFER_LIMIT) {
      // The array's data can be inline, and the buffer created lazily.
      return true;
    }

    ArrayBufferObject* buf = ArrayBufferObject::createZeroed(cx, byteLength);
    if (!buf) {
      return false;
    }

    buffer.set(buf);
    return true;
  }

  // ES2023 draft rev cf86f1cdc28e809170733d74ea64fd0f3dd79f78
  // 23.2.5.1.1 AllocateTypedArray ( constructorName, newTarget, defaultProto [
  // , length ] )
  static TypedArrayObject* fromLength(JSContext* cx, uint64_t nelements,
                                      HandleObject proto = nullptr,
                                      gc::Heap heap = gc::Heap::Default) {
    Rooted<ArrayBufferObject*> buffer(cx);
    if (!maybeCreateArrayBuffer(cx, nelements, &buffer)) {
      return nullptr;
    }

    return FixedLengthTypedArray::makeInstance(cx, buffer, 0, nelements, proto,
                                               heap);
  }

  static TypedArrayObject* fromArray(JSContext* cx, HandleObject other,
                                     HandleObject proto = nullptr);

  static TypedArrayObject* fromTypedArray(JSContext* cx, HandleObject other,
                                          bool isWrapped, HandleObject proto);

  static TypedArrayObject* fromObject(JSContext* cx, HandleObject other,
                                      HandleObject proto);

  static const NativeType getIndex(TypedArrayObject* tarray, size_t index) {
    MOZ_ASSERT(index < tarray->length().valueOr(0));
    return jit::AtomicOperations::loadSafeWhenRacy(
        tarray->dataPointerEither().cast<NativeType*>() + index);
  }

  static void setIndex(TypedArrayObject& tarray, size_t index, NativeType val) {
    MOZ_ASSERT(index < tarray.length().valueOr(0));
    jit::AtomicOperations::storeSafeWhenRacy(
        tarray.dataPointerEither().cast<NativeType*>() + index, val);
  }

  static bool getElement(JSContext* cx, TypedArrayObject* tarray, size_t index,
                         MutableHandleValue val);
  static bool getElementPure(TypedArrayObject* tarray, size_t index, Value* vp);

  static bool setElement(JSContext* cx, Handle<TypedArrayObject*> obj,
                         uint64_t index, HandleValue v, ObjectOpResult& result);
};

template <typename NativeType>
class FixedLengthTypedArrayObjectTemplate
    : public FixedLengthTypedArrayObject,
      public TypedArrayObjectTemplate<NativeType> {
  friend class js::TypedArrayObject;

  using TypedArrayTemplate = TypedArrayObjectTemplate<NativeType>;

 public:
  using TypedArrayTemplate::ArrayTypeID;
  using TypedArrayTemplate::BYTES_PER_ELEMENT;
  using TypedArrayTemplate::protoKey;

  static inline const JSClass* instanceClass() {
    static_assert(ArrayTypeID() <
                  std::size(TypedArrayObject::fixedLengthClasses));
    return &TypedArrayObject::fixedLengthClasses[ArrayTypeID()];
  }

  static FixedLengthTypedArrayObject* newBuiltinClassInstance(
      JSContext* cx, gc::AllocKind allocKind, gc::Heap heap) {
    RootedObject proto(cx, GlobalObject::getOrCreatePrototype(cx, protoKey()));
    if (!proto) {
      return nullptr;
    }
    return NewTypedArrayObject<FixedLengthTypedArrayObject>(
        cx, instanceClass(), proto, allocKind, heap);
  }

  static FixedLengthTypedArrayObject* makeProtoInstance(
      JSContext* cx, HandleObject proto, gc::AllocKind allocKind) {
    MOZ_ASSERT(proto);
    return NewTypedArrayObject<FixedLengthTypedArrayObject>(
        cx, instanceClass(), proto, allocKind, gc::Heap::Default);
  }

  static FixedLengthTypedArrayObject* makeInstance(
      JSContext* cx, Handle<ArrayBufferObjectMaybeShared*> buffer,
      size_t byteOffset, size_t len, HandleObject proto,
      gc::Heap heap = gc::Heap::Default) {
    MOZ_ASSERT(len <= ByteLengthLimit / BYTES_PER_ELEMENT);

    gc::AllocKind allocKind =
        buffer ? gc::GetGCObjectKind(instanceClass())
               : AllocKindForLazyBuffer(len * BYTES_PER_ELEMENT);

    AutoSetNewObjectMetadata metadata(cx);
    FixedLengthTypedArrayObject* obj;
    if (proto) {
      obj = makeProtoInstance(cx, proto, allocKind);
    } else {
      obj = newBuiltinClassInstance(cx, allocKind, heap);
    }
    if (!obj || !obj->init(cx, buffer, byteOffset, len, BYTES_PER_ELEMENT)) {
      return nullptr;
    }

    return obj;
  }

  static FixedLengthTypedArrayObject* makeTemplateObject(JSContext* cx,
                                                         int32_t len) {
    MOZ_ASSERT(len >= 0);
    size_t nbytes;
    MOZ_ALWAYS_TRUE(CalculateAllocSize<NativeType>(len, &nbytes));
    bool fitsInline = nbytes <= INLINE_BUFFER_LIMIT;
    gc::AllocKind allocKind = !fitsInline ? gc::GetGCObjectKind(instanceClass())
                                          : AllocKindForLazyBuffer(nbytes);
    MOZ_ASSERT(allocKind >= gc::GetGCObjectKind(instanceClass()));

    AutoSetNewObjectMetadata metadata(cx);

    auto* tarray = newBuiltinClassInstance(cx, allocKind, gc::Heap::Tenured);
    if (!tarray) {
      return nullptr;
    }

    initTypedArraySlots(tarray, len);

    // Template objects don't need memory for their elements, since there
    // won't be any elements to store.
    MOZ_ASSERT(tarray->getReservedSlot(DATA_SLOT).isUndefined());

    return tarray;
  }

  static void initTypedArraySlots(FixedLengthTypedArrayObject* tarray,
                                  int32_t len) {
    MOZ_ASSERT(len >= 0);
    tarray->initFixedSlot(TypedArrayObject::BUFFER_SLOT, JS::FalseValue());
    tarray->initFixedSlot(TypedArrayObject::LENGTH_SLOT, PrivateValue(len));
    tarray->initFixedSlot(TypedArrayObject::BYTEOFFSET_SLOT,
                          PrivateValue(size_t(0)));

#ifdef DEBUG
    if (len == 0) {
      uint8_t* output =
          tarray->fixedData(FixedLengthTypedArrayObject::FIXED_DATA_START);
      output[0] = TypedArrayObject::ZeroLengthArrayData;
    }
#endif
  }

  static void initTypedArrayData(FixedLengthTypedArrayObject* tarray, void* buf,
                                 size_t nbytes, gc::AllocKind allocKind) {
    if (buf) {
      InitReservedSlot(tarray, TypedArrayObject::DATA_SLOT, buf, nbytes,
                       MemoryUse::TypedArrayElements);
    } else {
#ifdef DEBUG
      constexpr size_t dataOffset = ArrayBufferViewObject::dataOffset();
      constexpr size_t offset = dataOffset + sizeof(HeapSlot);
      MOZ_ASSERT(offset + nbytes <= GetGCKindBytes(allocKind));
#endif

      void* data = tarray->fixedData(FIXED_DATA_START);
      tarray->initReservedSlot(DATA_SLOT, PrivateValue(data));
      memset(data, 0, nbytes);
    }
  }

  static FixedLengthTypedArrayObject* makeTypedArrayWithTemplate(
      JSContext* cx, TypedArrayObject* templateObj, int32_t len) {
    if (len < 0 || size_t(len) > ByteLengthLimit / BYTES_PER_ELEMENT) {
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                JSMSG_BAD_ARRAY_LENGTH);
      return nullptr;
    }

    size_t nbytes = size_t(len) * BYTES_PER_ELEMENT;
    MOZ_ASSERT(nbytes <= ByteLengthLimit);

    bool fitsInline = nbytes <= INLINE_BUFFER_LIMIT;

    AutoSetNewObjectMetadata metadata(cx);

    gc::AllocKind allocKind = !fitsInline ? gc::GetGCObjectKind(instanceClass())
                                          : AllocKindForLazyBuffer(nbytes);
    MOZ_ASSERT(templateObj->getClass() == instanceClass());

    RootedObject proto(cx, templateObj->staticPrototype());
    auto* obj = makeProtoInstance(cx, proto, allocKind);
    if (!obj) {
      return nullptr;
    }

    initTypedArraySlots(obj, len);

    void* buf = nullptr;
    if (!fitsInline) {
      MOZ_ASSERT(len > 0);

      nbytes = RoundUp(nbytes, sizeof(Value));
      buf = cx->nursery().allocateZeroedBuffer(obj, nbytes,
                                               js::ArrayBufferContentsArena);
      if (!buf) {
        ReportOutOfMemory(cx);
        return nullptr;
      }
    }

    initTypedArrayData(obj, buf, nbytes, allocKind);

    return obj;
  }
};

template <typename NativeType>
class ResizableTypedArrayObjectTemplate
    : public ResizableTypedArrayObject,
      public TypedArrayObjectTemplate<NativeType> {
  friend class js::TypedArrayObject;

  using TypedArrayTemplate = TypedArrayObjectTemplate<NativeType>;

 public:
  using TypedArrayTemplate::ArrayTypeID;
  using TypedArrayTemplate::BYTES_PER_ELEMENT;
  using TypedArrayTemplate::protoKey;

  static inline const JSClass* instanceClass() {
    static_assert(ArrayTypeID() <
                  std::size(TypedArrayObject::resizableClasses));
    return &TypedArrayObject::resizableClasses[ArrayTypeID()];
  }

  static ResizableTypedArrayObject* newBuiltinClassInstance(
      JSContext* cx, gc::AllocKind allocKind, gc::Heap heap) {
    RootedObject proto(cx, GlobalObject::getOrCreatePrototype(cx, protoKey()));
    if (!proto) {
      return nullptr;
    }
    return NewTypedArrayObject<ResizableTypedArrayObject>(
        cx, instanceClass(), proto, allocKind, heap);
  }

  static ResizableTypedArrayObject* makeProtoInstance(JSContext* cx,
                                                      HandleObject proto,
                                                      gc::AllocKind allocKind) {
    MOZ_ASSERT(proto);
    return NewTypedArrayObject<ResizableTypedArrayObject>(
        cx, instanceClass(), proto, allocKind, gc::Heap::Default);
  }

  static ResizableTypedArrayObject* makeInstance(
      JSContext* cx, Handle<ArrayBufferObjectMaybeShared*> buffer,
      size_t byteOffset, size_t len, AutoLength autoLength,
      HandleObject proto) {
    MOZ_ASSERT(buffer);
    MOZ_ASSERT(buffer->isResizable());
    MOZ_ASSERT(!buffer->isDetached());
    MOZ_ASSERT(autoLength == AutoLength::No || len == 0,
               "length is zero for 'auto' length views");
    MOZ_ASSERT(len <= ByteLengthLimit / BYTES_PER_ELEMENT);

    gc::AllocKind allocKind = gc::GetGCObjectKind(instanceClass());

    AutoSetNewObjectMetadata metadata(cx);
    ResizableTypedArrayObject* obj;
    if (proto) {
      obj = makeProtoInstance(cx, proto, allocKind);
    } else {
      obj = newBuiltinClassInstance(cx, allocKind, gc::Heap::Default);
    }
    if (!obj || !obj->initResizable(cx, buffer, byteOffset, len,
                                    BYTES_PER_ELEMENT, autoLength)) {
      return nullptr;
    }

    return obj;
  }

  static ResizableTypedArrayObject* makeTemplateObject(JSContext* cx) {
    gc::AllocKind allocKind = gc::GetGCObjectKind(instanceClass());

    AutoSetNewObjectMetadata metadata(cx);

    auto* tarray = newBuiltinClassInstance(cx, allocKind, gc::Heap::Tenured);
    if (!tarray) {
      return nullptr;
    }

    tarray->initFixedSlot(TypedArrayObject::BUFFER_SLOT, JS::FalseValue());
    tarray->initFixedSlot(TypedArrayObject::LENGTH_SLOT,
                          PrivateValue(size_t(0)));
    tarray->initFixedSlot(TypedArrayObject::BYTEOFFSET_SLOT,
                          PrivateValue(size_t(0)));
    tarray->initFixedSlot(AUTO_LENGTH_SLOT, BooleanValue(false));
    tarray->initFixedSlot(ResizableTypedArrayObject::INITIAL_LENGTH_SLOT,
                          PrivateValue(size_t(0)));
    tarray->initFixedSlot(ResizableTypedArrayObject::INITIAL_BYTE_OFFSET_SLOT,
                          PrivateValue(size_t(0)));

    // Template objects don't need memory for their elements, since there
    // won't be any elements to store.
    MOZ_ASSERT(tarray->getReservedSlot(DATA_SLOT).isUndefined());

    return tarray;
  }
};

template <typename NativeType>
bool TypedArrayObjectTemplate<NativeType>::convertValue(JSContext* cx,
                                                        HandleValue v,
                                                        NativeType* result) {
  double d;
  if (!ToNumber(cx, v, &d)) {
    return false;
  }

  if (js::SupportDifferentialTesting()) {
    // See the comment in ElementSpecific::doubleToNative.
    d = JS::CanonicalizeNaN(d);
  }

  // Assign based on characteristics of the destination type
  if constexpr (ArrayTypeIsFloatingPoint()) {
    *result = NativeType(d);
  } else if constexpr (ArrayTypeIsUnsigned()) {
    static_assert(sizeof(NativeType) <= 4);
    uint32_t n = ToUint32(d);
    *result = NativeType(n);
  } else if constexpr (ArrayTypeID() == Scalar::Uint8Clamped) {
    // The uint8_clamped type has a special rounding converter
    // for doubles.
    *result = NativeType(d);
  } else {
    static_assert(sizeof(NativeType) <= 4);
    int32_t n = ToInt32(d);
    *result = NativeType(n);
  }
  return true;
}

template <>
bool TypedArrayObjectTemplate<int64_t>::convertValue(JSContext* cx,
                                                     HandleValue v,
                                                     int64_t* result) {
  JS_TRY_VAR_OR_RETURN_FALSE(cx, *result, ToBigInt64(cx, v));
  return true;
}

template <>
bool TypedArrayObjectTemplate<uint64_t>::convertValue(JSContext* cx,
                                                      HandleValue v,
                                                      uint64_t* result) {
  JS_TRY_VAR_OR_RETURN_FALSE(cx, *result, ToBigUint64(cx, v));
  return true;
}

// https://tc39.github.io/proposal-bigint/#sec-integerindexedelementset
// 9.4.5.11 IntegerIndexedElementSet ( O, index, value )
template <typename NativeType>
/* static */ bool TypedArrayObjectTemplate<NativeType>::setElement(
    JSContext* cx, Handle<TypedArrayObject*> obj, uint64_t index, HandleValue v,
    ObjectOpResult& result) {
  MOZ_ASSERT(!obj->hasDetachedBuffer());
  MOZ_ASSERT(index < obj->length().valueOr(0));

  // Step 1 is enforced by the caller.

  // Steps 2-3.
  NativeType nativeValue;
  if (!convertValue(cx, v, &nativeValue)) {
    return false;
  }

  // Step 4.
  if (index < obj->length().valueOr(0)) {
    MOZ_ASSERT(!obj->hasDetachedBuffer(),
               "detaching an array buffer sets the length to zero");
    TypedArrayObjectTemplate<NativeType>::setIndex(*obj, index, nativeValue);
  }

  // Step 5.
  return result.succeed();
}

} /* anonymous namespace */

TypedArrayObject* js::NewTypedArrayWithTemplateAndLength(
    JSContext* cx, HandleObject templateObj, int32_t len) {
  MOZ_ASSERT(templateObj->is<TypedArrayObject>());
  TypedArrayObject* tobj = &templateObj->as<TypedArrayObject>();

  switch (tobj->type()) {
#define CREATE_TYPED_ARRAY(_, T, N)                                            \
  case Scalar::N:                                                              \
    return FixedLengthTypedArrayObjectTemplate<T>::makeTypedArrayWithTemplate( \
        cx, tobj, len);
    JS_FOR_EACH_TYPED_ARRAY(CREATE_TYPED_ARRAY)
#undef CREATE_TYPED_ARRAY
    default:
      MOZ_CRASH("Unsupported TypedArray type");
  }
}

TypedArrayObject* js::NewTypedArrayWithTemplateAndArray(
    JSContext* cx, HandleObject templateObj, HandleObject array) {
  MOZ_ASSERT(templateObj->is<TypedArrayObject>());
  TypedArrayObject* tobj = &templateObj->as<TypedArrayObject>();

  switch (tobj->type()) {
#define CREATE_TYPED_ARRAY(_, T, N)                                          \
  case Scalar::N:                                                            \
    return TypedArrayObjectTemplate<T>::makeTypedArrayWithTemplate(cx, tobj, \
                                                                   array);
    JS_FOR_EACH_TYPED_ARRAY(CREATE_TYPED_ARRAY)
#undef CREATE_TYPED_ARRAY
    default:
      MOZ_CRASH("Unsupported TypedArray type");
  }
}

TypedArrayObject* js::NewTypedArrayWithTemplateAndBuffer(
    JSContext* cx, HandleObject templateObj, HandleObject arrayBuffer,
    HandleValue byteOffset, HandleValue length) {
  MOZ_ASSERT(templateObj->is<TypedArrayObject>());
  TypedArrayObject* tobj = &templateObj->as<TypedArrayObject>();

  switch (tobj->type()) {
#define CREATE_TYPED_ARRAY(_, T, N)                                 \
  case Scalar::N:                                                   \
    return TypedArrayObjectTemplate<T>::makeTypedArrayWithTemplate( \
        cx, tobj, arrayBuffer, byteOffset, length);
    JS_FOR_EACH_TYPED_ARRAY(CREATE_TYPED_ARRAY)
#undef CREATE_TYPED_ARRAY
    default:
      MOZ_CRASH("Unsupported TypedArray type");
  }
}

TypedArrayObject* js::NewUint8ArrayWithLength(JSContext* cx, int32_t len,
                                              gc::Heap heap) {
  return TypedArrayObjectTemplate<uint8_t>::fromLength(cx, len, nullptr, heap);
}

template <typename T>
/* static */ TypedArrayObject* TypedArrayObjectTemplate<T>::fromArray(
    JSContext* cx, HandleObject other, HandleObject proto /* = nullptr */) {
  // Allow nullptr proto for FriendAPI methods, which don't care about
  // subclassing.
  if (other->is<TypedArrayObject>()) {
    return fromTypedArray(cx, other, /* wrapped= */ false, proto);
  }

  if (other->is<WrapperObject>() &&
      UncheckedUnwrap(other)->is<TypedArrayObject>()) {
    return fromTypedArray(cx, other, /* wrapped= */ true, proto);
  }

  return fromObject(cx, other, proto);
}

// ES2023 draft rev cf86f1cdc28e809170733d74ea64fd0f3dd79f78
// 23.2.5.1 TypedArray ( ...args )
// 23.2.5.1.2 InitializeTypedArrayFromTypedArray ( O, srcArray )
template <typename T>
/* static */ TypedArrayObject* TypedArrayObjectTemplate<T>::fromTypedArray(
    JSContext* cx, HandleObject other, bool isWrapped, HandleObject proto) {
  MOZ_ASSERT_IF(!isWrapped, other->is<TypedArrayObject>());
  MOZ_ASSERT_IF(isWrapped, other->is<WrapperObject>() &&
                               UncheckedUnwrap(other)->is<TypedArrayObject>());

  Rooted<TypedArrayObject*> srcArray(cx);
  if (!isWrapped) {
    srcArray = &other->as<TypedArrayObject>();
  } else {
    srcArray = other->maybeUnwrapAs<TypedArrayObject>();
    if (!srcArray) {
      ReportAccessDenied(cx);
      return nullptr;
    }
  }

  // InitializeTypedArrayFromTypedArray, step 1. (Skipped)

  // InitializeTypedArrayFromTypedArray, step 2.
  auto srcLength = srcArray->length();
  if (!srcLength) {
    ReportOutOfBounds(cx, srcArray);
    return nullptr;
  }

  // InitializeTypedArrayFromTypedArray, steps 3-7. (Skipped)

  // InitializeTypedArrayFromTypedArray, step 8.
  size_t elementLength = *srcLength;

  // InitializeTypedArrayFromTypedArray, step 9. (Skipped)

  // InitializeTypedArrayFromTypedArray, step 10.a. (Partial)
  // InitializeTypedArrayFromTypedArray, step 11.a.
  Rooted<ArrayBufferObject*> buffer(cx);
  if (!maybeCreateArrayBuffer(cx, elementLength, &buffer)) {
    return nullptr;
  }

  // InitializeTypedArrayFromTypedArray, step 11.b.
  if (Scalar::isBigIntType(ArrayTypeID()) !=
      Scalar::isBigIntType(srcArray->type())) {
    JS_ReportErrorNumberASCII(
        cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_NOT_COMPATIBLE,
        srcArray->getClass()->name,
        TypedArrayObject::fixedLengthClasses[ArrayTypeID()].name);
    return nullptr;
  }

  // Step 6.b.i.
  // InitializeTypedArrayFromTypedArray, steps 12-15.
  Rooted<TypedArrayObject*> obj(cx, FixedLengthTypedArray::makeInstance(
                                        cx, buffer, 0, elementLength, proto));
  if (!obj) {
    return nullptr;
  }

  MOZ_RELEASE_ASSERT(!srcArray->hasDetachedBuffer());

  // InitializeTypedArrayFromTypedArray, steps 10.a. (Remaining parts)
  // InitializeTypedArrayFromTypedArray, steps 11.c-f.
  MOZ_ASSERT(!obj->isSharedMemory());
  if (srcArray->isSharedMemory()) {
    if (!ElementSpecific<T, SharedOps>::setFromTypedArray(
            obj, elementLength, srcArray, elementLength, 0)) {
      MOZ_ASSERT_UNREACHABLE(
          "setFromTypedArray can only fail for overlapping buffers");
      return nullptr;
    }
  } else {
    if (!ElementSpecific<T, UnsharedOps>::setFromTypedArray(
            obj, elementLength, srcArray, elementLength, 0)) {
      MOZ_ASSERT_UNREACHABLE(
          "setFromTypedArray can only fail for overlapping buffers");
      return nullptr;
    }
  }

  // Step 6.b.v.
  return obj;
}

static MOZ_ALWAYS_INLINE bool IsOptimizableInit(JSContext* cx,
                                                HandleObject iterable,
                                                bool* optimized) {
  MOZ_ASSERT(!*optimized);

  if (!IsPackedArray(iterable)) {
    return true;
  }

  ForOfPIC::Chain* stubChain = ForOfPIC::getOrCreate(cx);
  if (!stubChain) {
    return false;
  }

  return stubChain->tryOptimizeArray(cx, iterable.as<ArrayObject>(), optimized);
}

// ES2023 draft rev cf86f1cdc28e809170733d74ea64fd0f3dd79f78
// 23.2.5.1 TypedArray ( ...args )
// 23.2.5.1.4 InitializeTypedArrayFromList ( O, values )
// 23.2.5.1.5 InitializeTypedArrayFromArrayLike ( O, arrayLike )
template <typename T>
/* static */ TypedArrayObject* TypedArrayObjectTemplate<T>::fromObject(
    JSContext* cx, HandleObject other, HandleObject proto) {
  // Steps 1-4 and 6.a (Already performed in caller).

  // Steps 6.b.i (Allocation deferred until later).

  // Steps 6.b.ii-iii. (Not applicable)

  // Step 6.b.iv.

  bool optimized = false;
  if (!IsOptimizableInit(cx, other, &optimized)) {
    return nullptr;
  }

  // Fast path when iterable is a packed array using the default iterator.
  if (optimized) {
    // Steps 6.b.iv.2-3. (We don't need to call IterableToList for the fast
    // path).
    Handle<ArrayObject*> array = other.as<ArrayObject>();

    // InitializeTypedArrayFromList, step 1.
    size_t len = array->getDenseInitializedLength();

    // InitializeTypedArrayFromList, step 2.
    Rooted<ArrayBufferObject*> buffer(cx);
    if (!maybeCreateArrayBuffer(cx, len, &buffer)) {
      return nullptr;
    }

    // Steps 6.b.i.
    Rooted<FixedLengthTypedArrayObject*> obj(
        cx, FixedLengthTypedArray::makeInstance(cx, buffer, 0, len, proto));
    if (!obj) {
      return nullptr;
    }

    // InitializeTypedArrayFromList, steps 3-4.
    MOZ_ASSERT(!obj->isSharedMemory());
    if (!ElementSpecific<T, UnsharedOps>::initFromIterablePackedArray(cx, obj,
                                                                      array)) {
      return nullptr;
    }

    // InitializeTypedArrayFromList, step 5. (The assertion isn't applicable for
    // the fast path).

    // Step 6.b.v.
    return obj;
  }

  // Step 6.b.iv.1 (Assertion; implicit in our implementation).

  // Step 6.b.iv.2.
  RootedValue callee(cx);
  RootedId iteratorId(cx, PropertyKey::Symbol(cx->wellKnownSymbols().iterator));
  if (!GetProperty(cx, other, other, iteratorId, &callee)) {
    return nullptr;
  }

  // Steps 6.b.iv.3-4.
  RootedObject arrayLike(cx);
  if (!callee.isNullOrUndefined()) {
    // Throw if other[Symbol.iterator] isn't callable.
    if (!callee.isObject() || !callee.toObject().isCallable()) {
      RootedValue otherVal(cx, ObjectValue(*other));
      UniqueChars bytes =
          DecompileValueGenerator(cx, JSDVG_SEARCH_STACK, otherVal, nullptr);
      if (!bytes) {
        return nullptr;
      }
      JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_NOT_ITERABLE,
                               bytes.get());
      return nullptr;
    }

    FixedInvokeArgs<2> args2(cx);
    args2[0].setObject(*other);
    args2[1].set(callee);

    // Step 6.b.iv.3.a.
    RootedValue rval(cx);
    if (!CallSelfHostedFunction(cx, cx->names().IterableToList,
                                UndefinedHandleValue, args2, &rval)) {
      return nullptr;
    }

    // Step 6.b.iv.3.b (Implemented below).
    arrayLike = &rval.toObject();
  } else {
    // Step 4.a is an assertion: object is not an Iterator. Testing this is
    // literally the very last thing we did, so we don't assert here.

    // Step 4.b (Implemented below).
    arrayLike = other;
  }

  // We implement InitializeTypedArrayFromList in terms of
  // InitializeTypedArrayFromArrayLike.

  // InitializeTypedArrayFromArrayLike, step 1.
  uint64_t len;
  if (!GetLengthProperty(cx, arrayLike, &len)) {
    return nullptr;
  }

  // InitializeTypedArrayFromArrayLike, step 2.
  Rooted<ArrayBufferObject*> buffer(cx);
  if (!maybeCreateArrayBuffer(cx, len, &buffer)) {
    return nullptr;
  }

  MOZ_ASSERT(len <= ByteLengthLimit / BYTES_PER_ELEMENT);

  // Steps 6.b.i.
  Rooted<TypedArrayObject*> obj(
      cx, FixedLengthTypedArray::makeInstance(cx, buffer, 0, len, proto));
  if (!obj) {
    return nullptr;
  }

  // InitializeTypedArrayFromArrayLike, steps 3-4.
  MOZ_ASSERT(!obj->isSharedMemory());
  if (!ElementSpecific<T, UnsharedOps>::setFromNonTypedArray(cx, obj, arrayLike,
                                                             len)) {
    return nullptr;
  }

  // Step 6.b.v.
  return obj;
}

static bool TypedArrayConstructor(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                            JSMSG_TYPED_ARRAY_CALL_OR_CONSTRUCT,
                            args.isConstructing() ? "construct" : "call");
  return false;
}

template <typename T>
static bool GetTemplateObjectForNative(JSContext* cx,
                                       const JS::HandleValueArray args,
                                       MutableHandleObject res) {
  if (args.length() == 0) {
    return true;
  }

  HandleValue arg = args[0];
  if (arg.isInt32()) {
    uint32_t len = 0;
    if (arg.toInt32() >= 0) {
      len = arg.toInt32();
    }

    size_t nbytes;
    if (!js::CalculateAllocSize<T>(len, &nbytes) ||
        nbytes > TypedArrayObject::ByteLengthLimit) {
      return true;
    }

    res.set(
        FixedLengthTypedArrayObjectTemplate<T>::makeTemplateObject(cx, len));
    return !!res;
  }

  if (!arg.isObject()) {
    return true;
  }
  auto* obj = &arg.toObject();

  // We don't support wrappers, because of the complicated interaction between
  // wrapped ArrayBuffers and TypedArrays, see |fromBufferWrapped()|.
  if (IsWrapper(obj)) {
    return true;
  }

  // We don't use the template's length in the object case, so we can create
  // the template typed array with an initial length of zero.
  uint32_t len = 0;

  if (!obj->is<ArrayBufferObjectMaybeShared>() ||
      !obj->as<ArrayBufferObjectMaybeShared>().isResizable()) {
    res.set(
        FixedLengthTypedArrayObjectTemplate<T>::makeTemplateObject(cx, len));
  } else {
    res.set(ResizableTypedArrayObjectTemplate<T>::makeTemplateObject(cx));
  }
  return !!res;
}

/* static */ bool TypedArrayObject::GetTemplateObjectForNative(
    JSContext* cx, Native native, const JS::HandleValueArray args,
    MutableHandleObject res) {
  MOZ_ASSERT(!res);
#define CHECK_TYPED_ARRAY_CONSTRUCTOR(_, T, N)                     \
  if (native == &TypedArrayObjectTemplate<T>::class_constructor) { \
    return ::GetTemplateObjectForNative<T>(cx, args, res);         \
  }
  JS_FOR_EACH_TYPED_ARRAY(CHECK_TYPED_ARRAY_CONSTRUCTOR)
#undef CHECK_TYPED_ARRAY_CONSTRUCTOR
  return true;
}

static bool LengthGetterImpl(JSContext* cx, const CallArgs& args) {
  auto* tarr = &args.thisv().toObject().as<TypedArrayObject>();
  args.rval().setNumber(tarr->length().valueOr(0));
  return true;
}

static bool TypedArray_lengthGetter(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  return CallNonGenericMethod<IsTypedArrayObject, LengthGetterImpl>(cx, args);
}

static bool ByteOffsetGetterImpl(JSContext* cx, const CallArgs& args) {
  auto* tarr = &args.thisv().toObject().as<TypedArrayObject>();
  args.rval().setNumber(tarr->byteOffset().valueOr(0));
  return true;
}

static bool TypedArray_byteOffsetGetter(JSContext* cx, unsigned argc,
                                        Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  return CallNonGenericMethod<IsTypedArrayObject, ByteOffsetGetterImpl>(cx,
                                                                        args);
}

static bool ByteLengthGetterImpl(JSContext* cx, const CallArgs& args) {
  auto* tarr = &args.thisv().toObject().as<TypedArrayObject>();
  args.rval().setNumber(tarr->byteLength().valueOr(0));
  return true;
}

static bool TypedArray_byteLengthGetter(JSContext* cx, unsigned argc,
                                        Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  return CallNonGenericMethod<IsTypedArrayObject, ByteLengthGetterImpl>(cx,
                                                                        args);
}

static bool BufferGetterImpl(JSContext* cx, const CallArgs& args) {
  MOZ_ASSERT(IsTypedArrayObject(args.thisv()));
  Rooted<TypedArrayObject*> tarray(
      cx, &args.thisv().toObject().as<TypedArrayObject>());
  if (!TypedArrayObject::ensureHasBuffer(cx, tarray)) {
    return false;
  }
  args.rval().set(tarray->bufferValue());
  return true;
}

static bool TypedArray_bufferGetter(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  return CallNonGenericMethod<IsTypedArrayObject, BufferGetterImpl>(cx, args);
}

// ES2019 draft rev fc9ecdcd74294d0ca3146d4b274e2a8e79565dc3
// 22.2.3.32 get %TypedArray%.prototype [ @@toStringTag ]
static bool TypedArray_toStringTagGetter(JSContext* cx, unsigned argc,
                                         Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);

  // Steps 1-2.
  if (!args.thisv().isObject()) {
    args.rval().setUndefined();
    return true;
  }

  JSObject* obj = CheckedUnwrapStatic(&args.thisv().toObject());
  if (!obj) {
    ReportAccessDenied(cx);
    return false;
  }

  // Step 3.
  if (!obj->is<TypedArrayObject>()) {
    args.rval().setUndefined();
    return true;
  }

  // Steps 4-6.
  JSProtoKey protoKey = StandardProtoKeyOrNull(obj);
  MOZ_ASSERT(protoKey);

  args.rval().setString(ClassName(protoKey, cx));
  return true;
}

/* static */ const JSPropertySpec TypedArrayObject::protoAccessors[] = {
    JS_PSG("length", TypedArray_lengthGetter, 0),
    JS_PSG("buffer", TypedArray_bufferGetter, 0),
    JS_PSG("byteLength", TypedArray_byteLengthGetter, 0),
    JS_PSG("byteOffset", TypedArray_byteOffsetGetter, 0),
    JS_SYM_GET(toStringTag, TypedArray_toStringTagGetter, 0),
    JS_PS_END};

template <typename T>
static inline bool SetFromTypedArray(Handle<TypedArrayObject*> target,
                                     size_t targetLength,
                                     Handle<TypedArrayObject*> source,
                                     size_t sourceLength, size_t offset) {
  // WARNING: |source| may be an unwrapped typed array from a different
  // compartment. Proceed with caution!

  if (target->isSharedMemory() || source->isSharedMemory()) {
    return ElementSpecific<T, SharedOps>::setFromTypedArray(
        target, targetLength, source, sourceLength, offset);
  }
  return ElementSpecific<T, UnsharedOps>::setFromTypedArray(
      target, targetLength, source, sourceLength, offset);
}

template <typename T>
static inline bool SetFromNonTypedArray(JSContext* cx,
                                        Handle<TypedArrayObject*> target,
                                        HandleObject source, size_t len,
                                        size_t offset) {
  MOZ_ASSERT(!source->is<TypedArrayObject>(), "use SetFromTypedArray");

  if (target->isSharedMemory()) {
    return ElementSpecific<T, SharedOps>::setFromNonTypedArray(
        cx, target, source, len, offset);
  }
  return ElementSpecific<T, UnsharedOps>::setFromNonTypedArray(
      cx, target, source, len, offset);
}

// ES2023 draft rev 22cc56ab08fcab92a865978c0aa5c6f1d8ce250f
// 23.2.3.24.1 SetTypedArrayFromTypedArray ( target, targetOffset, source )
static bool SetTypedArrayFromTypedArray(JSContext* cx,
                                        Handle<TypedArrayObject*> target,
                                        double targetOffset,
                                        size_t targetLength,
                                        Handle<TypedArrayObject*> source) {
  // WARNING: |source| may be an unwrapped typed array from a different
  // compartment. Proceed with caution!

  MOZ_ASSERT(targetOffset >= 0);

  // Steps 1-3. (Performed in caller.)
  MOZ_ASSERT(!target->hasDetachedBuffer());

  // Steps 4-5.
  auto sourceLength = source->length();
  if (!sourceLength) {
    ReportOutOfBounds(cx, source);
    return false;
  }

  // Steps 13-14 (Split into two checks to provide better error messages).
  if (targetOffset > targetLength) {
    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_INDEX);
    return false;
  }

  // Step 14 (Cont'd).
  size_t offset = size_t(targetOffset);
  if (*sourceLength > targetLength - offset) {
    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                              JSMSG_SOURCE_ARRAY_TOO_LONG);
    return false;
  }

  // Step 15.
  if (Scalar::isBigIntType(target->type()) !=
      Scalar::isBigIntType(source->type())) {
    JS_ReportErrorNumberASCII(
        cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_NOT_COMPATIBLE,
        source->getClass()->name, target->getClass()->name);
    return false;
  }

  // Steps 6-12, 16-24.
  switch (target->type()) {
#define SET_FROM_TYPED_ARRAY(_, T, N)                                      \
  case Scalar::N:                                                          \
    if (!SetFromTypedArray<T>(target, targetLength, source, *sourceLength, \
                              offset)) {                                   \
      ReportOutOfMemory(cx);                                               \
      return false;                                                        \
    }                                                                      \
    break;
    JS_FOR_EACH_TYPED_ARRAY(SET_FROM_TYPED_ARRAY)
#undef SET_FROM_TYPED_ARRAY
    default:
      MOZ_CRASH("Unsupported TypedArray type");
  }

  return true;
}

// ES2023 draft rev 22cc56ab08fcab92a865978c0aa5c6f1d8ce250f
// 23.2.3.24.1 SetTypedArrayFromArrayLike ( target, targetOffset, source )
static bool SetTypedArrayFromArrayLike(JSContext* cx,
                                       Handle<TypedArrayObject*> target,
                                       double targetOffset, size_t targetLength,
                                       HandleObject src) {
  MOZ_ASSERT(targetOffset >= 0);

  // Steps 1-2. (Performed in caller.)
  MOZ_ASSERT(target->length().isSome());

  // Steps 3-4. (Performed in caller.)

  // Step 5.
  uint64_t srcLength;
  if (!GetLengthProperty(cx, src, &srcLength)) {
    return false;
  }

  // Steps 6-7 (Split into two checks to provide better error messages).
  if (targetOffset > targetLength) {
    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_INDEX);
    return false;
  }

  // Step 7 (Cont'd).
  size_t offset = size_t(targetOffset);
  if (srcLength > targetLength - offset) {
    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                              JSMSG_SOURCE_ARRAY_TOO_LONG);
    return false;
  }

  MOZ_ASSERT(srcLength <= targetLength);

  // Steps 8-9.
  if (srcLength > 0) {
    switch (target->type()) {
#define SET_FROM_NON_TYPED_ARRAY(_, T, N)                             \
  case Scalar::N:                                                     \
    if (!SetFromNonTypedArray<T>(cx, target, src, srcLength, offset)) \
      return false;                                                   \
    break;
      JS_FOR_EACH_TYPED_ARRAY(SET_FROM_NON_TYPED_ARRAY)
#undef SET_FROM_NON_TYPED_ARRAY
      default:
        MOZ_CRASH("Unsupported TypedArray type");
    }
  }

  // Step 10.
  return true;
}

// ES2023 draft rev 22cc56ab08fcab92a865978c0aa5c6f1d8ce250f
// 23.2.3.24 %TypedArray%.prototype.set ( source [ , offset ] )
// 23.2.3.24.1 SetTypedArrayFromTypedArray ( target, targetOffset, source )
// 23.2.3.24.2 SetTypedArrayFromArrayLike ( target, targetOffset, source )
/* static */
bool TypedArrayObject::set_impl(JSContext* cx, const CallArgs& args) {
  MOZ_ASSERT(IsTypedArrayObject(args.thisv()));

  // Steps 1-3 (Validation performed as part of CallNonGenericMethod).
  Rooted<TypedArrayObject*> target(
      cx, &args.thisv().toObject().as<TypedArrayObject>());

  // Steps 4-5.
  double targetOffset = 0;
  if (args.length() > 1) {
    // Step 4.
    if (!ToInteger(cx, args[1], &targetOffset)) {
      return false;
    }

    // Step 5.
    if (targetOffset < 0) {
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_INDEX);
      return false;
    }
  }

  // 23.2.3.24.1, steps 1-2.
  // 23.2.3.24.2, steps 1-2.
  auto targetLength = target->length();
  if (!targetLength) {
    ReportOutOfBounds(cx, target);
    return false;
  }

  // 23.2.3.24.2, step 4. (23.2.3.24.1 only applies if args[0] is a typed
  // array, so it doesn't make a difference there to apply ToObject here.)
  RootedObject src(cx, ToObject(cx, args.get(0)));
  if (!src) {
    return false;
  }

  Rooted<TypedArrayObject*> srcTypedArray(cx);
  {
    JSObject* obj = CheckedUnwrapStatic(src);
    if (!obj) {
      ReportAccessDenied(cx);
      return false;
    }

    if (obj->is<TypedArrayObject>()) {
      srcTypedArray = &obj->as<TypedArrayObject>();
    }
  }

  // Steps 6-7.
  if (srcTypedArray) {
    if (!SetTypedArrayFromTypedArray(cx, target, targetOffset, *targetLength,
                                     srcTypedArray)) {
      return false;
    }
  } else {
    if (!SetTypedArrayFromArrayLike(cx, target, targetOffset, *targetLength,
                                    src)) {
      return false;
    }
  }

  // Step 8.
  args.rval().setUndefined();
  return true;
}

/* static */
bool TypedArrayObject::set(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  return CallNonGenericMethod<IsTypedArrayObject, TypedArrayObject::set_impl>(
      cx, args);
}

// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9
// 22.2.3.5 %TypedArray%.prototype.copyWithin ( target, start [ , end ] )
/* static */
bool TypedArrayObject::copyWithin_impl(JSContext* cx, const CallArgs& args) {
  MOZ_ASSERT(IsTypedArrayObject(args.thisv()));

  // Steps 1-2.
  Rooted<TypedArrayObject*> tarray(
      cx, &args.thisv().toObject().as<TypedArrayObject>());

  auto arrayLength = tarray->length();
  if (!arrayLength) {
    ReportOutOfBounds(cx, tarray);
    return false;
  }

  // Step 3.
  size_t len = *arrayLength;

  // Step 4.
  double relativeTarget;
  if (!ToInteger(cx, args.get(0), &relativeTarget)) {
    return false;
  }

  // Step 5.
  uint64_t to;
  if (relativeTarget < 0) {
    to = std::max(len + relativeTarget, 0.0);
  } else {
    to = std::min(relativeTarget, double(len));
  }

  // Step 6.
  double relativeStart;
  if (!ToInteger(cx, args.get(1), &relativeStart)) {
    return false;
  }

  // Step 7.
  uint64_t from;
  if (relativeStart < 0) {
    from = std::max(len + relativeStart, 0.0);
  } else {
    from = std::min(relativeStart, double(len));
  }

  // Step 8.
  double relativeEnd;
  if (!args.hasDefined(2)) {
    relativeEnd = len;
  } else {
    if (!ToInteger(cx, args[2], &relativeEnd)) {
      return false;
    }
  }

  // Step 9.
  uint64_t final_;
  if (relativeEnd < 0) {
    final_ = std::max(len + relativeEnd, 0.0);
  } else {
    final_ = std::min(relativeEnd, double(len));
  }

  // Step 10.
  MOZ_ASSERT(to <= len);
  uint64_t count;
  if (from <= final_) {
    count = std::min(final_ - from, len - to);
  } else {
    count = 0;
  }

  // Step 11.
  //
  // Note that this copies elements effectively by memmove, *not* in
  // step 11's specified order.  This is unobservable, even when the underlying
  // buffer is a SharedArrayBuffer instance, because the access is unordered and
  // therefore is allowed to have data races.

  if (count == 0) {
    args.rval().setObject(*tarray);
    return true;
  }

  // Reacquire the length because side-effects may have detached or resized the
  // array buffer.
  arrayLength = tarray->length();
  if (!arrayLength) {
    ReportOutOfBounds(cx, tarray);
    return false;
  }

  // Recompute the bounds if the current length is smaller.
  if (*arrayLength < len) {
    MOZ_ASSERT(to + count <= len);
    MOZ_ASSERT(from + count <= len);

    len = *arrayLength;

    // Don't copy any bytes if either index is no longer in-bounds.
    if (to >= len || from >= len) {
      args.rval().setObject(*tarray);
      return true;
    }

    // Restrict |count| to not copy any bytes after the end of the array.
    count = std::min(count, std::min(len - to, len - from));
    MOZ_ASSERT(count > 0);
  }

  // Don't multiply by |tarray->bytesPerElement()| in case the compiler can't
  // strength-reduce multiplication by 1/2/4/8 into the equivalent shift.
  const size_t ElementShift = TypedArrayShift(tarray->type());

  MOZ_ASSERT((SIZE_MAX >> ElementShift) > to);
  size_t byteDest = to << ElementShift;

  MOZ_ASSERT((SIZE_MAX >> ElementShift) > from);
  size_t byteSrc = from << ElementShift;

  MOZ_ASSERT((SIZE_MAX >> ElementShift) >= count);
  size_t byteSize = count << ElementShift;

#ifdef DEBUG
  {
    size_t viewByteLength = len << ElementShift;
    MOZ_ASSERT(byteSize <= viewByteLength);
    MOZ_ASSERT(byteDest < viewByteLength);
    MOZ_ASSERT(byteSrc < viewByteLength);
    MOZ_ASSERT(byteDest <= viewByteLength - byteSize);
    MOZ_ASSERT(byteSrc <= viewByteLength - byteSize);
  }
#endif

  SharedMem<uint8_t*> data = tarray->dataPointerEither().cast<uint8_t*>();
  if (tarray->isSharedMemory()) {
    jit::AtomicOperations::memmoveSafeWhenRacy(data + byteDest, data + byteSrc,
                                               byteSize);
  } else {
    memmove(data.unwrapUnshared() + byteDest, data.unwrapUnshared() + byteSrc,
            byteSize);
  }

  args.rval().setObject(*tarray);
  return true;
}

/* static */
bool TypedArrayObject::copyWithin(JSContext* cx, unsigned argc, Value* vp) {
  AutoJSMethodProfilerEntry pseudoFrame(cx, "[TypedArray].prototype",
                                        "copyWithin");
  CallArgs args = CallArgsFromVp(argc, vp);
  return CallNonGenericMethod<IsTypedArrayObject,
                              TypedArrayObject::copyWithin_impl>(cx, args);
}

// Byte vector with large enough inline storage to allow constructing small
// typed arrays without extra heap allocations.
using ByteVector =
    js::Vector<uint8_t, FixedLengthTypedArrayObject::INLINE_BUFFER_LIMIT>;

static UniqueChars QuoteString(JSContext* cx, char16_t ch) {
  Sprinter sprinter(cx);
  if (!sprinter.init()) {
    return nullptr;
  }

  StringEscape esc{};
  js::EscapePrinter ep(sprinter, esc);
  ep.putChar(ch);

  return sprinter.release();
}

/**
 * FromHex ( string [ , maxLength ] )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-fromhex
 */
static bool FromHex(JSContext* cx, Handle<JSString*> string, size_t maxLength,
                    ByteVector& bytes, size_t* readLength) {
  // Step 1. (Not applicable in our implementation.)

  // Step 2.
  size_t length = string->length();

  // Step 3.
  if (length % 2 != 0) {
    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                              JSMSG_TYPED_ARRAY_BAD_HEX_STRING_LENGTH);
    return false;
  }

  JSLinearString* linear = string->ensureLinear(cx);
  if (!linear) {
    return false;
  }

  // Step 4. (Not applicable in our implementation.)
  MOZ_ASSERT(bytes.empty());

  // Step 5.
  size_t index = 0;

  // Step 6.
  while (index < length && bytes.length() < maxLength) {
    // Step 6.a.
    char16_t c0 = linear->latin1OrTwoByteChar(index);
    char16_t c1 = linear->latin1OrTwoByteChar(index + 1);

    // Step 6.b.
    if (MOZ_UNLIKELY(!mozilla::IsAsciiHexDigit(c0) ||
                     !mozilla::IsAsciiHexDigit(c1))) {
      char16_t ch = !mozilla::IsAsciiHexDigit(c0) ? c0 : c1;
      if (auto str = QuoteString(cx, ch)) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                  JSMSG_TYPED_ARRAY_BAD_HEX_DIGIT, str.get());
      }
      return false;
    }

    // Step 6.c.
    index += 2;

    // Step 6.d.
    uint8_t byte = (mozilla::AsciiAlphanumericToNumber(c0) << 4) +
                   mozilla::AsciiAlphanumericToNumber(c1);

    // Step 6.e.
    if (!bytes.append(byte)) {
      return false;
    }
  }

  // Step 7.
  *readLength = index;
  return true;
}

namespace Base64 {
static constexpr uint8_t InvalidChar = UINT8_MAX;

static constexpr auto DecodeTable(const char (&alphabet)[65]) {
  std::array<uint8_t, 128> result = {};

  // Initialize all elements to InvalidChar.
  for (auto& e : result) {
    e = InvalidChar;
  }

  // Map the base64 characters to their values.
  for (uint8_t i = 0; i < 64; ++i) {
    result[alphabet[i]] = i;
  }

  return result;
}
}  // namespace Base64

namespace Base64::Encode {
static constexpr const char Base64[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static_assert(std::char_traits<char>::length(Base64) == 64);

static constexpr const char Base64Url[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
static_assert(std::char_traits<char>::length(Base64Url) == 64);
}  // namespace Base64::Encode

namespace Base64::Decode {
static constexpr auto Base64 = DecodeTable(Base64::Encode::Base64);
static_assert(Base64.size() == 128,
              "128 elements to allow access through ASCII characters");

static constexpr auto Base64Url = DecodeTable(Base64::Encode::Base64Url);
static_assert(Base64Url.size() == 128,
              "128 elements to allow access through ASCII characters");
}  // namespace Base64::Decode

enum class Alphabet {
  /**
   * Standard base64 alphabet.
   */
  Base64,

  /**
   * URL and filename safe base64 alphabet.
   */
  Base64Url,
};

enum class LastChunkHandling {
  /**
   * Allow partial chunks at the end of the input.
   */
  Loose,

  /**
   * Disallow partial chunks at the end of the input.
   */
  Strict,

  /**
   * Stop before partial chunks at the end of the input.
   */
  StopBeforePartial,
};

/**
 * FromBase64 ( string, alphabet, lastChunkHandling [ , maxLength ] )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-frombase64
 */
static bool FromBase64(JSContext* cx, Handle<JSString*> string,
                       Alphabet alphabet, LastChunkHandling lastChunkHandling,
                       size_t maxLength, ByteVector& bytes,
                       size_t* readLength) {
  // Steps 1-2. (Not applicable in our implementation.)

  // Step 3.
  size_t remaining = maxLength;
  if (remaining == 0) {
    MOZ_ASSERT(bytes.empty());
    *readLength = 0;
    return true;
  }

  JSLinearString* linear = string->ensureLinear(cx);
  if (!linear) {
    return false;
  }

  // DecodeBase64Chunk ( chunk [ , throwOnExtraBits ] )
  //
  // Encode a complete base64 chunk.
  auto decodeChunk = [&](uint32_t chunk) {
    MOZ_ASSERT(chunk <= 0xffffff);
    MOZ_ASSERT(remaining >= 3);

    if (!bytes.reserve(bytes.length() + 3)) {
      return false;
    }
    bytes.infallibleAppend(chunk >> 16);
    bytes.infallibleAppend(chunk >> 8);
    bytes.infallibleAppend(chunk);
    return true;
  };

  // DecodeBase64Chunk ( chunk [ , throwOnExtraBits ] )
  //
  // Encode a three element partial base64 chunk.
  auto decodeChunk3 = [&](uint32_t chunk, bool throwOnExtraBits) {
    MOZ_ASSERT(chunk <= 0x3ffff);
    MOZ_ASSERT(remaining >= 2);

    if (throwOnExtraBits && (chunk & 0x3) != 0) {
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                JSMSG_TYPED_ARRAY_EXTRA_BASE64_BITS);
      return false;
    }

    if (!bytes.reserve(bytes.length() + 2)) {
      return false;
    }
    bytes.infallibleAppend(chunk >> 10);
    bytes.infallibleAppend(chunk >> 2);
    return true;
  };

  // DecodeBase64Chunk ( chunk [ , throwOnExtraBits ] )
  //
  // Encode a two element partial base64 chunk.
  auto decodeChunk2 = [&](uint32_t chunk, bool throwOnExtraBits) {
    MOZ_ASSERT(chunk <= 0xfff);
    MOZ_ASSERT(remaining >= 1);

    if (throwOnExtraBits && (chunk & 0xf) != 0) {
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                JSMSG_TYPED_ARRAY_EXTRA_BASE64_BITS);
      return false;
    }

    if (!bytes.reserve(bytes.length() + 1)) {
      return false;
    }
    bytes.infallibleAppend(chunk >> 4);
    return true;
  };

  // DecodeBase64Chunk ( chunk [ , throwOnExtraBits ] )
  //
  // Encode a partial base64 chunk.
  auto decodePartialChunk = [&](uint32_t chunk, uint32_t chunkLength,
                                bool throwOnExtraBits = false) {
    MOZ_ASSERT(chunkLength == 2 || chunkLength == 3);
    return chunkLength == 2 ? decodeChunk2(chunk, throwOnExtraBits)
                            : decodeChunk3(chunk, throwOnExtraBits);
  };

  // Step 4.
  //
  // String index after the last fully read base64 chunk.
  size_t read = 0;

  // Step 5.
  MOZ_ASSERT(bytes.empty());

  // Step 6.
  //
  // Current base64 chunk, a uint24 number.
  uint32_t chunk = 0;

  // Step 7.
  //
  // Current base64 chunk length, in the range [0..4].
  size_t chunkLength = 0;

  // Step 8.
  //
  // Current string index.
  size_t index = 0;

  // Step 9.
  size_t length = linear->length();

  const auto& decode = alphabet == Alphabet::Base64 ? Base64::Decode::Base64
                                                    : Base64::Decode::Base64Url;

  // Step 10.
  for (; index < length; index++) {
    // Step 10.c. (Reordered)
    char16_t ch = linear->latin1OrTwoByteChar(index);

    // Step 10.a.
    if (mozilla::IsAsciiWhitespace(ch)) {
      continue;
    }

    // Step 10.b. (Moved out of loop.)

    // Step 10.d. (Performed in for-loop step.)

    // Step 10.e.
    if (ch == '=') {
      break;
    }

    // Steps 10.f-g.
    uint8_t value = Base64::InvalidChar;
    if (mozilla::IsAscii(ch)) {
      value = decode[ch];
    }
    if (MOZ_UNLIKELY(value == Base64::InvalidChar)) {
      if (auto str = QuoteString(cx, ch)) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                  JSMSG_TYPED_ARRAY_BAD_BASE64_CHAR, str.get());
      }
      return false;
    }

    // Step 10.h. (Not applicable in our implementation.)

    // Step 10.i.
    if ((remaining == 1 && chunkLength == 2) ||
        (remaining == 2 && chunkLength == 3)) {
      *readLength = read;
      return true;
    }

    // Step 10.j.
    chunk = (chunk << 6) | value;

    // Step 10.k.
    chunkLength += 1;

    // Step 10.l.
    if (chunkLength == 4) {
      // Step 10.l.i.
      if (!decodeChunk(chunk)) {
        return false;
      }

      // Step 10.l.ii.
      chunk = 0;

      // Step 10.l.iii.
      chunkLength = 0;

      // Step 10.l.iv.
      //
      // NB: Add +1 to include the |index| update from step 10.d.
      read = index + 1;

      // Step 10.l.v.
      MOZ_ASSERT(remaining >= 3);
      remaining -= 3;
      if (remaining == 0) {
        *readLength = read;
        return true;
      }
    }
  }

  // Step 10.b.
  if (index == length) {
    // Step 10.b.i.
    if (chunkLength > 0) {
      // Step 10.b.i.1.
      if (lastChunkHandling == LastChunkHandling::StopBeforePartial) {
        *readLength = read;
        return true;
      }

      // Steps 10.b.i.2-3.
      if (lastChunkHandling == LastChunkHandling::Loose) {
        // Step 10.b.i.2.a.
        if (chunkLength == 1) {
          JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                    JSMSG_TYPED_ARRAY_BAD_INCOMPLETE_CHUNK);
          return false;
        }
        MOZ_ASSERT(chunkLength == 2 || chunkLength == 3);

        // Step 10.b.i.2.b.
        if (!decodePartialChunk(chunk, chunkLength)) {
          return false;
        }
      } else {
        // Step 10.b.i.3.a.
        MOZ_ASSERT(lastChunkHandling == LastChunkHandling::Strict);

        // Step 10.b.i.3.b.
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                  JSMSG_TYPED_ARRAY_BAD_INCOMPLETE_CHUNK);
        return false;
      }
    }

    // Step 10.b.ii.
    *readLength = length;
    return true;
  }

  // Step 10.e.
  MOZ_ASSERT(index < length);
  MOZ_ASSERT(linear->latin1OrTwoByteChar(index) == '=');

  // Step 10.e.i.
  if (chunkLength < 2) {
    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                              JSMSG_TYPED_ARRAY_BAD_INCOMPLETE_CHUNK);
    return false;
  }
  MOZ_ASSERT(chunkLength == 2 || chunkLength == 3);

  // Step 10.e.ii. (Inlined SkipAsciiWhitespace)
  while (++index < length) {
    char16_t ch = linear->latin1OrTwoByteChar(index);
    if (!mozilla::IsAsciiWhitespace(ch)) {
      break;
    }
  }

  // Step 10.e.iii.
  if (chunkLength == 2) {
    // Step 10.e.iii.1.
    if (index == length) {
      // Step 10.e.iii.1.a.
      if (lastChunkHandling == LastChunkHandling::StopBeforePartial) {
        *readLength = read;
        return true;
      }

      // Step 10.e.iii.1.b.
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                JSMSG_TYPED_ARRAY_MISSING_BASE64_PADDING);
      return false;
    }

    // Step 10.e.iii.2.
    char16_t ch = linear->latin1OrTwoByteChar(index);

    // Step 10.e.iii.3.
    if (ch == '=') {
      // Step 10.e.iii.3.a. (Inlined SkipAsciiWhitespace)
      while (++index < length) {
        char16_t ch = linear->latin1OrTwoByteChar(index);
        if (!mozilla::IsAsciiWhitespace(ch)) {
          break;
        }
      }
    }
  }

  // Step 10.e.iv.
  if (index < length) {
    char16_t ch = linear->latin1OrTwoByteChar(index);
    if (auto str = QuoteString(cx, ch)) {
      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                JSMSG_TYPED_ARRAY_BAD_BASE64_AFTER_PADDING,
                                str.get());
    }
    return false;
  }

  // Steps 10.e.v-vi.
  bool throwOnExtraBits = lastChunkHandling == LastChunkHandling::Strict;

  // Step 10.e.vii.
  if (!decodePartialChunk(chunk, chunkLength, throwOnExtraBits)) {
    return false;
  }

  // Step 10.e.viii.
  *readLength = length;
  return true;
}

/**
 * Uint8Array.fromBase64 ( string [ , options ] )
 * Uint8Array.prototype.setFromBase64 ( string [ , options ] )
 * Uint8Array.prototype.toBase64 ( [ options ] )
 *
 * Helper to retrieve the "alphabet" option.
 */
static bool GetAlphabetOption(JSContext* cx, Handle<JSObject*> options,
                              Alphabet* result) {
  Rooted<Value> value(cx);
  if (!GetProperty(cx, options, options, cx->names().alphabet, &value)) {
    return false;
  }

  if (value.isUndefined()) {
    *result = Alphabet::Base64;
    return true;
  }

  if (!value.isString()) {
    return ReportValueError(cx, JSMSG_UNEXPECTED_TYPE, JSDVG_IGNORE_STACK,
                            value, nullptr, "not a string");
  }

  auto* linear = value.toString()->ensureLinear(cx);
  if (!linear) {
    return false;
  }

  if (StringEqualsAscii(linear, "base64")) {
    *result = Alphabet::Base64;
    return true;
  }

  if (StringEqualsAscii(linear, "base64url")) {
    *result = Alphabet::Base64Url;
    return true;
  }

  JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                            JSMSG_TYPED_ARRAY_BAD_BASE64_ALPHABET);
  return false;
}

/**
 * Uint8Array.fromBase64 ( string [ , options ] )
 * Uint8Array.prototype.setFromBase64 ( string [ , options ] )
 *
 * Helper to retrieve the "lastChunkHandling" option.
 */
static bool GetLastChunkHandlingOption(JSContext* cx, Handle<JSObject*> options,
                                       LastChunkHandling* result) {
  Rooted<Value> value(cx);
  if (!GetProperty(cx, options, options, cx->names().lastChunkHandling,
                   &value)) {
    return false;
  }

  if (value.isUndefined()) {
    *result = LastChunkHandling::Loose;
    return true;
  }

  if (!value.isString()) {
    return ReportValueError(cx, JSMSG_UNEXPECTED_TYPE, JSDVG_IGNORE_STACK,
                            value, nullptr, "not a string");
  }

  auto* linear = value.toString()->ensureLinear(cx);
  if (!linear) {
    return false;
  }

  if (StringEqualsAscii(linear, "loose")) {
    *result = LastChunkHandling::Loose;
    return true;
  }

  if (StringEqualsAscii(linear, "strict")) {
    *result = LastChunkHandling::Strict;
    return true;
  }

  if (StringEqualsAscii(linear, "stop-before-partial")) {
    *result = LastChunkHandling::StopBeforePartial;
    return true;
  }

  JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                            JSMSG_TYPED_ARRAY_BAD_BASE64_LAST_CHUNK_HANDLING);
  return false;
}

/**
 * Uint8Array.fromBase64 ( string [ , options ] )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.frombase64
 */
static bool uint8array_fromBase64(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);

  // Step 1.
  if (!args.get(0).isString()) {
    return ReportValueError(cx, JSMSG_UNEXPECTED_TYPE, JSDVG_SEARCH_STACK,
                            args.get(0), nullptr, "not a string");
  }
  Rooted<JSString*> string(cx, args[0].toString());

  // Steps 2-9.
  auto alphabet = Alphabet::Base64;
  auto lastChunkHandling = LastChunkHandling::Loose;
  if (args.hasDefined(1)) {
    // Step 2. (Inlined GetOptionsObject)
    Rooted<JSObject*> options(
        cx, RequireObjectArg(cx, "options", "fromBase64", args[1]));
    if (!options) {
      return false;
    }

    // Steps 3-6.
    if (!GetAlphabetOption(cx, options, &alphabet)) {
      return false;
    }

    // Steps 7-9.
    if (!GetLastChunkHandlingOption(cx, options, &lastChunkHandling)) {
      return false;
    }
  }

  // Step 10.
  constexpr size_t maxLength = std::numeric_limits<size_t>::max();
  ByteVector bytes(cx);
  size_t unusedReadLength;
  if (!FromBase64(cx, string, alphabet, lastChunkHandling, maxLength, bytes,
                  &unusedReadLength)) {
    return false;
  }

  // Step 11.
  size_t resultLength = bytes.length();

  // Step 12.
  auto* tarray =
      TypedArrayObjectTemplate<uint8_t>::fromLength(cx, resultLength);
  if (!tarray) {
    return false;
  }

  // Step 13.
  auto target = SharedMem<uint8_t*>::unshared(tarray->dataPointerUnshared());
  auto source = SharedMem<uint8_t*>::unshared(bytes.begin());
  UnsharedOps::podCopy(target, source, resultLength);

  // Step 14.
  args.rval().setObject(*tarray);
  return true;
}

/**
 * Uint8Array.fromHex ( string )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.fromhex
 */
static bool uint8array_fromHex(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);

  // Step 1.
  if (!args.get(0).isString()) {
    return ReportValueError(cx, JSMSG_UNEXPECTED_TYPE, JSDVG_SEARCH_STACK,
                            args.get(0), nullptr, "not a string");
  }
  Rooted<JSString*> string(cx, args[0].toString());

  // Step 2.
  constexpr size_t maxLength = std::numeric_limits<size_t>::max();
  ByteVector bytes(cx);
  size_t unusedReadLength;
  if (!FromHex(cx, string, maxLength, bytes, &unusedReadLength)) {
    return false;
  }

  // Step 3.
  size_t resultLength = bytes.length();

  // Step 4.
  auto* tarray =
      TypedArrayObjectTemplate<uint8_t>::fromLength(cx, resultLength);
  if (!tarray) {
    return false;
  }

  // Step 5.
  auto target = SharedMem<uint8_t*>::unshared(tarray->dataPointerUnshared());
  auto source = SharedMem<uint8_t*>::unshared(bytes.begin());
  UnsharedOps::podCopy(target, source, resultLength);

  // Step 6.
  args.rval().setObject(*tarray);
  return true;
}

/**
 * Uint8Array.prototype.setFromBase64 ( string [ , options ] )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.prototype.setfrombase64
 */
static bool uint8array_setFromBase64(JSContext* cx, const CallArgs& args) {
  Rooted<TypedArrayObject*> tarray(
      cx, &args.thisv().toObject().as<TypedArrayObject>());

  // Step 3.
  if (!args.get(0).isString()) {
    return ReportValueError(cx, JSMSG_UNEXPECTED_TYPE, JSDVG_SEARCH_STACK,
                            args.get(0), nullptr, "not a string");
  }
  Rooted<JSString*> string(cx, args[0].toString());

  // Steps 4-11.
  auto alphabet = Alphabet::Base64;
  auto lastChunkHandling = LastChunkHandling::Loose;
  if (args.hasDefined(1)) {
    // Step 2. (Inlined GetOptionsObject)
    Rooted<JSObject*> options(
        cx, RequireObjectArg(cx, "options", "setFromBase64", args[1]));
    if (!options) {
      return false;
    }

    // Steps 3-6.
    if (!GetAlphabetOption(cx, options, &alphabet)) {
      return false;
    }

    // Steps 7-9.
    if (!GetLastChunkHandlingOption(cx, options, &lastChunkHandling)) {
      return false;
    }
  }

  // Steps 12-14.
  auto length = tarray->length();
  if (!length) {
    ReportOutOfBounds(cx, tarray);
    return false;
  }

  // Step 15.
  size_t maxLength = *length;

  // Steps 16-17.
  ByteVector bytes(cx);
  size_t readLength;
  if (!FromBase64(cx, string, alphabet, lastChunkHandling, maxLength, bytes,
                  &readLength)) {
    return false;
  }

  // Step 18.
  size_t written = bytes.length();

  // Step 19.
  //
  // The underlying buffer has neither been detached nor shrunk. (It may have
  // been grown when it's a growable shared buffer and a concurrent thread
  // resized the buffer.)
  MOZ_ASSERT(!tarray->hasDetachedBuffer());
  MOZ_ASSERT(tarray->length().valueOr(0) >= *length);

  // Step 20.
  MOZ_ASSERT(written <= *length);

  // Step 21. (Inlined SetUint8ArrayBytes)
  auto target = tarray->dataPointerEither().cast<uint8_t*>();
  auto source = SharedMem<uint8_t*>::unshared(bytes.begin());
  if (tarray->isSharedMemory()) {
    SharedOps::podCopy(target, source, written);
  } else {
    UnsharedOps::podCopy(target, source, written);
  }

  // Step 22.
  Rooted<PlainObject*> result(cx, NewPlainObject(cx));
  if (!result) {
    return false;
  }

  // Step 23.
  Rooted<Value> readValue(cx, NumberValue(readLength));
  if (!DefineDataProperty(cx, result, cx->names().read, readValue)) {
    return false;
  }

  // Step 24.
  Rooted<Value> writtenValue(cx, NumberValue(written));
  if (!DefineDataProperty(cx, result, cx->names().written, writtenValue)) {
    return false;
  }

  // Step 25.
  args.rval().setObject(*result);
  return true;
}

/**
 * Uint8Array.prototype.setFromBase64 ( string [ , options ] )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.prototype.setfrombase64
 */
static bool uint8array_setFromBase64(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);

  // Steps 1-2.
  return CallNonGenericMethod<IsUint8ArrayObject, uint8array_setFromBase64>(
      cx, args);
}

/**
 * Uint8Array.prototype.setFromHex ( string )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.prototype.setfromhex
 */
static bool uint8array_setFromHex(JSContext* cx, const CallArgs& args) {
  Rooted<TypedArrayObject*> tarray(
      cx, &args.thisv().toObject().as<TypedArrayObject>());

  // Step 3.
  if (!args.get(0).isString()) {
    return ReportValueError(cx, JSMSG_UNEXPECTED_TYPE, JSDVG_SEARCH_STACK,
                            args.get(0), nullptr, "not a string");
  }
  Rooted<JSString*> string(cx, args[0].toString());

  // Steps 4-6.
  auto length = tarray->length();
  if (!length) {
    ReportOutOfBounds(cx, tarray);
    return false;
  }

  // Step 7.
  size_t maxLength = *length;

  // Steps 8-9.
  ByteVector bytes(cx);
  size_t readLength;
  if (!FromHex(cx, string, maxLength, bytes, &readLength)) {
    return false;
  }

  // Step 10.
  size_t written = bytes.length();

  // Step 11.
  //
  // The underlying buffer has neither been detached nor shrunk. (It may have
  // been grown when it's a growable shared buffer and a concurrent thread
  // resized the buffer.)
  MOZ_ASSERT(!tarray->hasDetachedBuffer());
  MOZ_ASSERT(tarray->length().valueOr(0) >= *length);

  // Step 12.
  MOZ_ASSERT(written <= *length);

  // Step 13. (Inlined SetUint8ArrayBytes)
  auto target = tarray->dataPointerEither().cast<uint8_t*>();
  auto source = SharedMem<uint8_t*>::unshared(bytes.begin());
  if (tarray->isSharedMemory()) {
    SharedOps::podCopy(target, source, written);
  } else {
    UnsharedOps::podCopy(target, source, written);
  }

  // Step 14.
  Rooted<PlainObject*> result(cx, NewPlainObject(cx));
  if (!result) {
    return false;
  }

  // Step 15.
  Rooted<Value> readValue(cx, NumberValue(readLength));
  if (!DefineDataProperty(cx, result, cx->names().read, readValue)) {
    return false;
  }

  // Step 16.
  Rooted<Value> writtenValue(cx, NumberValue(written));
  if (!DefineDataProperty(cx, result, cx->names().written, writtenValue)) {
    return false;
  }

  // Step 17.
  args.rval().setObject(*result);
  return true;
}

/**
 * Uint8Array.prototype.setFromHex ( string )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.prototype.setfromhex
 */
static bool uint8array_setFromHex(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);

  // Steps 1-2.
  return CallNonGenericMethod<IsUint8ArrayObject, uint8array_setFromHex>(cx,
                                                                         args);
}

/**
 * Uint8Array.prototype.toBase64 ( [ options ] )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.prototype.tobase64
 */
static bool uint8array_toBase64(JSContext* cx, const CallArgs& args) {
  Rooted<TypedArrayObject*> tarray(
      cx, &args.thisv().toObject().as<TypedArrayObject>());

  // Steps 3-7.
  auto alphabet = Alphabet::Base64;
  if (args.hasDefined(0)) {
    // Step 3. (Inlined GetOptionsObject)
    Rooted<JSObject*> options(
        cx, RequireObjectArg(cx, "options", "toBase64", args[0]));
    if (!options) {
      return false;
    }

    // Steps 4-7.
    if (!GetAlphabetOption(cx, options, &alphabet)) {
      return false;
    }
  }

  // Step 8. (Partial)
  auto length = tarray->length();
  if (!length) {
    ReportOutOfBounds(cx, tarray);
    return false;
  }

  // Compute the output string length. Three input bytes are encoded as four
  // characters, so the output length is ⌈length × 4/3⌉.
  auto outLength = mozilla::CheckedInt<size_t>{*length};
  outLength += 2;
  outLength /= 3;
  outLength *= 4;
  if (!outLength.isValid() || outLength.value() > JSString::MAX_LENGTH) {
    ReportAllocationOverflow(cx);
    return false;
  }

  JSStringBuilder sb(cx);
  if (!sb.reserve(outLength.value())) {
    return false;
  }

  // Steps 9-10.
  const auto& base64Chars = alphabet == Alphabet::Base64
                                ? Base64::Encode::Base64
                                : Base64::Encode::Base64Url;

  auto encode = [&base64Chars](uint32_t value) {
    return base64Chars[value & 0x3f];
  };

  // Our implementation directly converts the bytes to their string
  // representation instead of first collecting them into an intermediate list.
  auto data = tarray->dataPointerEither().cast<uint8_t*>();
  auto toRead = *length;
  for (; toRead >= 3; toRead -= 3) {
    // Combine three input bytes into a single uint24 value.
    auto byte0 = jit::AtomicOperations::loadSafeWhenRacy(data++);
    auto byte1 = jit::AtomicOperations::loadSafeWhenRacy(data++);
    auto byte2 = jit::AtomicOperations::loadSafeWhenRacy(data++);
    auto u24 = (uint32_t(byte0) << 16) | (uint32_t(byte1) << 8) | byte2;

    // Encode the uint24 value as base64.
    sb.infallibleAppend(encode(u24 >> 18));
    sb.infallibleAppend(encode(u24 >> 12));
    sb.infallibleAppend(encode(u24 >> 6));
    sb.infallibleAppend(encode(u24 >> 0));
  }

  // Trailing two and one element bytes are padded with '='.
  if (toRead == 2) {
    // Combine two input bytes into a single uint24 value.
    auto byte0 = jit::AtomicOperations::loadSafeWhenRacy(data++);
    auto byte1 = jit::AtomicOperations::loadSafeWhenRacy(data++);
    auto u24 = (uint32_t(byte0) << 16) | (uint32_t(byte1) << 8);

    // Encode the uint24 value as base64, including padding.
    sb.infallibleAppend(encode(u24 >> 18));
    sb.infallibleAppend(encode(u24 >> 12));
    sb.infallibleAppend(encode(u24 >> 6));
    sb.infallibleAppend('=');
  } else if (toRead == 1) {
    // Combine one input byte into a single uint24 value.
    auto byte0 = jit::AtomicOperations::loadSafeWhenRacy(data++);
    auto u24 = uint32_t(byte0) << 16;

    // Encode the uint24 value as base64, including padding.
    sb.infallibleAppend(encode(u24 >> 18));
    sb.infallibleAppend(encode(u24 >> 12));
    sb.infallibleAppend('=');
    sb.infallibleAppend('=');
  } else {
    MOZ_ASSERT(toRead == 0);
  }

  MOZ_ASSERT(sb.length() == outLength.value(), "all characters were written");

  // Step 11.
  auto* str = sb.finishString();
  if (!str) {
    return false;
  }

  args.rval().setString(str);
  return true;
}

/**
 * Uint8Array.prototype.toBase64 ( [ options ] )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.prototype.tobase64
 */
static bool uint8array_toBase64(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);

  // Steps 1-2.
  return CallNonGenericMethod<IsUint8ArrayObject, uint8array_toBase64>(cx,
                                                                       args);
}

/**
 * Uint8Array.prototype.toHex ( )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.prototype.tohex
 */
static bool uint8array_toHex(JSContext* cx, const CallArgs& args) {
  Rooted<TypedArrayObject*> tarray(
      cx, &args.thisv().toObject().as<TypedArrayObject>());

  // Step 3. (Partial)
  auto length = tarray->length();
  if (!length) {
    ReportOutOfBounds(cx, tarray);
    return false;
  }

  // |length| is limited by |ByteLengthLimit|, which ensures that multiplying it
  // by two won't overflow.
  static_assert(TypedArrayObject::ByteLengthLimit <=
                std::numeric_limits<size_t>::max() / 2);
  MOZ_ASSERT(*length <= TypedArrayObject::ByteLengthLimit);

  // Compute the output string length. Each byte is encoded as two characters,
  // so the output length is exactly twice as large as |length|.
  size_t outLength = *length * 2;
  if (outLength > JSString::MAX_LENGTH) {
    ReportAllocationOverflow(cx);
    return false;
  }

  // Step 4.
  JSStringBuilder sb(cx);
  if (!sb.reserve(outLength)) {
    return false;
  }

  // NB: Lower case hex digits.
  static constexpr char HexDigits[] = "0123456789abcdef";
  static_assert(std::char_traits<char>::length(HexDigits) == 16);

  // Steps 3 and 5.
  //
  // Our implementation directly converts the bytes to their string
  // representation instead of first collecting them into an intermediate list.
  auto data = tarray->dataPointerEither().cast<uint8_t*>();
  for (size_t index = 0; index < *length; index++) {
    auto byte = jit::AtomicOperations::loadSafeWhenRacy(data + index);

    sb.infallibleAppend(HexDigits[byte >> 4]);
    sb.infallibleAppend(HexDigits[byte & 0xf]);
  }

  MOZ_ASSERT(sb.length() == outLength, "all characters were written");

  // Step 6.
  auto* str = sb.finishString();
  if (!str) {
    return false;
  }

  args.rval().setString(str);
  return true;
}

/**
 * Uint8Array.prototype.toHex ( )
 *
 * https://tc39.es/proposal-arraybuffer-base64/spec/#sec-uint8array.prototype.tohex
 */
static bool uint8array_toHex(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);

  // Steps 1-2.
  return CallNonGenericMethod<IsUint8ArrayObject, uint8array_toHex>(cx, args);
}

/* static */ const JSFunctionSpec TypedArrayObject::protoFunctions[] = {
    JS_SELF_HOSTED_FN("subarray", "TypedArraySubarray", 2, 0),
    JS_FN("set", TypedArrayObject::set, 1, 0),
    JS_FN("copyWithin", TypedArrayObject::copyWithin, 2, 0),
    JS_SELF_HOSTED_FN("every", "TypedArrayEvery", 1, 0),
    JS_SELF_HOSTED_FN("fill", "TypedArrayFill", 3, 0),
    JS_SELF_HOSTED_FN("filter", "TypedArrayFilter", 1, 0),
    JS_SELF_HOSTED_FN("find", "TypedArrayFind", 1, 0),
    JS_SELF_HOSTED_FN("findIndex", "TypedArrayFindIndex", 1, 0),
    JS_SELF_HOSTED_FN("findLast", "TypedArrayFindLast", 1, 0),
    JS_SELF_HOSTED_FN("findLastIndex", "TypedArrayFindLastIndex", 1, 0),
    JS_SELF_HOSTED_FN("forEach", "TypedArrayForEach", 1, 0),
    JS_SELF_HOSTED_FN("indexOf", "TypedArrayIndexOf", 2, 0),
    JS_SELF_HOSTED_FN("join", "TypedArrayJoin", 1, 0),
    JS_SELF_HOSTED_FN("lastIndexOf", "TypedArrayLastIndexOf", 1, 0),
    JS_SELF_HOSTED_FN("map", "TypedArrayMap", 1, 0),
    JS_SELF_HOSTED_FN("reduce", "TypedArrayReduce", 1, 0),
    JS_SELF_HOSTED_FN("reduceRight", "TypedArrayReduceRight", 1, 0),
    JS_SELF_HOSTED_FN("reverse", "TypedArrayReverse", 0, 0),
    JS_SELF_HOSTED_FN("slice", "TypedArraySlice", 2, 0),
    JS_SELF_HOSTED_FN("some", "TypedArraySome", 1, 0),
    JS_SELF_HOSTED_FN("sort", "TypedArraySort", 1, 0),
    JS_SELF_HOSTED_FN("entries", "TypedArrayEntries", 0, 0),
    JS_SELF_HOSTED_FN("keys", "TypedArrayKeys", 0, 0),
    JS_SELF_HOSTED_FN("values", "$TypedArrayValues", 0, 0),
    JS_SELF_HOSTED_SYM_FN(iterator, "$TypedArrayValues", 0, 0),
    JS_SELF_HOSTED_FN("includes", "TypedArrayIncludes", 2, 0),
    JS_SELF_HOSTED_FN("toString", "ArrayToString", 0, 0),
    JS_SELF_HOSTED_FN("toLocaleString", "TypedArrayToLocaleString", 2, 0),
    JS_SELF_HOSTED_FN("at", "TypedArrayAt", 1, 0),
    JS_SELF_HOSTED_FN("toReversed", "TypedArrayToReversed", 0, 0),
    JS_SELF_HOSTED_FN("toSorted", "TypedArrayToSorted", 1, 0),
    JS_SELF_HOSTED_FN("with", "TypedArrayWith", 2, 0),
    JS_FS_END,
};

/* static */ const JSFunctionSpec TypedArrayObject::staticFunctions[] = {
    JS_SELF_HOSTED_FN("from", "TypedArrayStaticFrom", 3, 0),
    JS_SELF_HOSTED_FN("of", "TypedArrayStaticOf", 0, 0),
    JS_FS_END,
};

/* static */ const JSPropertySpec TypedArrayObject::staticProperties[] = {
    JS_SELF_HOSTED_SYM_GET(species, "$TypedArraySpecies", 0),
    JS_PS_END,
};

static JSObject* CreateSharedTypedArrayPrototype(JSContext* cx,
                                                 JSProtoKey key) {
  return GlobalObject::createBlankPrototype(
      cx, cx->global(), &TypedArrayObject::sharedTypedArrayPrototypeClass);
}

static const ClassSpec TypedArrayObjectSharedTypedArrayPrototypeClassSpec = {
    GenericCreateConstructor<TypedArrayConstructor, 0, gc::AllocKind::FUNCTION>,
    CreateSharedTypedArrayPrototype,
    TypedArrayObject::staticFunctions,
    TypedArrayObject::staticProperties,
    TypedArrayObject::protoFunctions,
    TypedArrayObject::protoAccessors,
    nullptr,
    ClassSpec::DontDefineConstructor,
};

/* static */ const JSClass TypedArrayObject::sharedTypedArrayPrototypeClass = {
    "TypedArrayPrototype",
    JSCLASS_HAS_CACHED_PROTO(JSProto_TypedArray),
    JS_NULL_CLASS_OPS,
    &TypedArrayObjectSharedTypedArrayPrototypeClassSpec,
};

namespace {

// This default implementation is only valid for integer types less
// than 32-bits in size.
template <typename NativeType>
bool TypedArrayObjectTemplate<NativeType>::getElementPure(
    TypedArrayObject* tarray, size_t index, Value* vp) {
  static_assert(sizeof(NativeType) < 4,
                "this method must only handle NativeType values that are "
                "always exact int32_t values");

  *vp = Int32Value(getIndex(tarray, index));
  return true;
}

// We need to specialize for floats and other integer types.
template <>
bool TypedArrayObjectTemplate<int32_t>::getElementPure(TypedArrayObject* tarray,
                                                       size_t index,
                                                       Value* vp) {
  *vp = Int32Value(getIndex(tarray, index));
  return true;
}

template <>
bool TypedArrayObjectTemplate<uint32_t>::getElementPure(
    TypedArrayObject* tarray, size_t index, Value* vp) {
  uint32_t val = getIndex(tarray, index);
  *vp = NumberValue(val);
  return true;
}

template <>
bool TypedArrayObjectTemplate<float>::getElementPure(TypedArrayObject* tarray,
                                                     size_t index, Value* vp) {
  float val = getIndex(tarray, index);
  double dval = val;

  /*
   * Doubles in typed arrays could be typed-punned arrays of integers. This
   * could allow user code to break the engine-wide invariant that only
   * canonical nans are stored into jsvals, which means user code could
   * confuse the engine into interpreting a double-typed jsval as an
   * object-typed jsval.
   *
   * This could be removed for platforms/compilers known to convert a 32-bit
   * non-canonical nan to a 64-bit canonical nan.
   */
  *vp = JS::CanonicalizedDoubleValue(dval);
  return true;
}

template <>
bool TypedArrayObjectTemplate<double>::getElementPure(TypedArrayObject* tarray,
                                                      size_t index, Value* vp) {
  double val = getIndex(tarray, index);

  /*
   * Doubles in typed arrays could be typed-punned arrays of integers. This
   * could allow user code to break the engine-wide invariant that only
   * canonical nans are stored into jsvals, which means user code could
   * confuse the engine into interpreting a double-typed jsval as an
   * object-typed jsval.
   */
  *vp = JS::CanonicalizedDoubleValue(val);
  return true;
}

template <>
bool TypedArrayObjectTemplate<int64_t>::getElementPure(TypedArrayObject* tarray,
                                                       size_t index,
                                                       Value* vp) {
  return false;
}

template <>
bool TypedArrayObjectTemplate<uint64_t>::getElementPure(
    TypedArrayObject* tarray, size_t index, Value* vp) {
  return false;
}
} /* anonymous namespace */

namespace {

template <typename NativeType>
bool TypedArrayObjectTemplate<NativeType>::getElement(JSContext* cx,
                                                      TypedArrayObject* tarray,
                                                      size_t index,
                                                      MutableHandleValue val) {
  MOZ_ALWAYS_TRUE(getElementPure(tarray, index, val.address()));
  return true;
}

template <>
bool TypedArrayObjectTemplate<int64_t>::getElement(JSContext* cx,
                                                   TypedArrayObject* tarray,
                                                   size_t index,
                                                   MutableHandleValue val) {
  int64_t n = getIndex(tarray, index);
  BigInt* res = BigInt::createFromInt64(cx, n);
  if (!res) {
    return false;
  }
  val.setBigInt(res);
  return true;
}

template <>
bool TypedArrayObjectTemplate<uint64_t>::getElement(JSContext* cx,
                                                    TypedArrayObject* tarray,
                                                    size_t index,
                                                    MutableHandleValue val) {
  uint64_t n = getIndex(tarray, index);
  BigInt* res = BigInt::createFromUint64(cx, n);
  if (!res) {
    return false;
  }
  val.setBigInt(res);
  return true;
}
} /* anonymous namespace */

namespace js {

template <>
bool TypedArrayObject::getElement<CanGC>(JSContext* cx, size_t index,
                                         MutableHandleValue val) {
  switch (type()) {
#define GET_ELEMENT(_, T, N) \
  case Scalar::N:            \
    return TypedArrayObjectTemplate<T>::getElement(cx, this, index, val);
    JS_FOR_EACH_TYPED_ARRAY(GET_ELEMENT)
#undef GET_ELEMENT
    case Scalar::MaxTypedArrayViewType:
    case Scalar::Int64:
    case Scalar::Simd128:
      break;
  }

  MOZ_CRASH("Unknown TypedArray type");
}

template <>
bool TypedArrayObject::getElement<NoGC>(
    JSContext* cx, size_t index,
    typename MaybeRooted<Value, NoGC>::MutableHandleType vp) {
  return getElementPure(index, vp.address());
}

}  // namespace js

bool TypedArrayObject::getElementPure(size_t index, Value* vp) {
  switch (type()) {
#define GET_ELEMENT_PURE(_, T, N) \
  case Scalar::N:                 \
    return TypedArrayObjectTemplate<T>::getElementPure(this, index, vp);
    JS_FOR_EACH_TYPED_ARRAY(GET_ELEMENT_PURE)
#undef GET_ELEMENT
    case Scalar::MaxTypedArrayViewType:
    case Scalar::Int64:
    case Scalar::Simd128:
      break;
  }

  MOZ_CRASH("Unknown TypedArray type");
}

/* static */
bool TypedArrayObject::getElements(JSContext* cx,
                                   Handle<TypedArrayObject*> tarray,
                                   Value* vp) {
  size_t length = tarray->length().valueOr(0);
  MOZ_ASSERT_IF(length > 0, !tarray->hasDetachedBuffer());

  switch (tarray->type()) {
#define GET_ELEMENTS(_, T, N)                                               \
  case Scalar::N:                                                           \
    for (size_t i = 0; i < length; ++i, ++vp) {                             \
      if (!TypedArrayObjectTemplate<T>::getElement(                         \
              cx, tarray, i, MutableHandleValue::fromMarkedLocation(vp))) { \
        return false;                                                       \
      }                                                                     \
    }                                                                       \
    return true;
    JS_FOR_EACH_TYPED_ARRAY(GET_ELEMENTS)
#undef GET_ELEMENTS
    case Scalar::MaxTypedArrayViewType:
    case Scalar::Int64:
    case Scalar::Simd128:
      break;
  }

  MOZ_CRASH("Unknown TypedArray type");
}

/***
 *** JS impl
 ***/

/*
 * TypedArrayObject boilerplate
 */

static const JSClassOps TypedArrayClassOps = {
    nullptr,                                // addProperty
    nullptr,                                // delProperty
    nullptr,                                // enumerate
    nullptr,                                // newEnumerate
    nullptr,                                // resolve
    nullptr,                                // mayResolve
    FixedLengthTypedArrayObject::finalize,  // finalize
    nullptr,                                // call
    nullptr,                                // construct
    ArrayBufferViewObject::trace,           // trace
};

static const JSClassOps ResizableTypedArrayClassOps = {
    nullptr,                       // addProperty
    nullptr,                       // delProperty
    nullptr,                       // enumerate
    nullptr,                       // newEnumerate
    nullptr,                       // resolve
    nullptr,                       // mayResolve
    nullptr,                       // finalize
    nullptr,                       // call
    nullptr,                       // construct
    ArrayBufferViewObject::trace,  // trace
};

static const ClassExtension TypedArrayClassExtension = {
    FixedLengthTypedArrayObject::objectMoved,  // objectMovedOp
};

static const JSPropertySpec
    static_prototype_properties[Scalar::MaxTypedArrayViewType][2] = {
#define IMPL_TYPED_ARRAY_PROPERTIES(ExternalType, NativeType, Name)        \
  {                                                                        \
      JS_INT32_PS("BYTES_PER_ELEMENT",                                     \
                  TypedArrayObjectTemplate<NativeType>::BYTES_PER_ELEMENT, \
                  JSPROP_READONLY | JSPROP_PERMANENT),                     \
      JS_PS_END,                                                           \
  },

        JS_FOR_EACH_TYPED_ARRAY(IMPL_TYPED_ARRAY_PROPERTIES)
#undef IMPL_TYPED_ARRAY_PROPERTIES
};

static const JSFunctionSpec uint8array_static_methods[] = {
    JS_FN("fromBase64", uint8array_fromBase64, 1, 0),
    JS_FN("fromHex", uint8array_fromHex, 1, 0),
    JS_FS_END,
};

static const JSFunctionSpec uint8array_methods[] = {
    JS_FN("setFromBase64", uint8array_setFromBase64, 1, 0),
    JS_FN("setFromHex", uint8array_setFromHex, 1, 0),
    JS_FN("toBase64", uint8array_toBase64, 0, 0),
    JS_FN("toHex", uint8array_toHex, 0, 0),
    JS_FS_END,
};

static constexpr const JSFunctionSpec* TypedArrayStaticMethods(
    Scalar::Type type) {
  if (type == Scalar::Uint8) {
    return uint8array_static_methods;
  }
  return nullptr;
}

static constexpr const JSFunctionSpec* TypedArrayMethods(Scalar::Type type) {
  if (type == Scalar::Uint8) {
    return uint8array_methods;
  }
  return nullptr;
}

static const ClassSpec
    TypedArrayObjectClassSpecs[Scalar::MaxTypedArrayViewType] = {
#define IMPL_TYPED_ARRAY_CLASS_SPEC(ExternalType, NativeType, Name) \
  {                                                                 \
      TypedArrayObjectTemplate<NativeType>::createConstructor,      \
      TypedArrayObjectTemplate<NativeType>::createPrototype,        \
      TypedArrayStaticMethods(Scalar::Type::Name),                  \
      static_prototype_properties[Scalar::Type::Name],              \
      TypedArrayMethods(Scalar::Type::Name),                        \
      static_prototype_properties[Scalar::Type::Name],              \
      nullptr,                                                      \
      JSProto_TypedArray,                                           \
  },

        JS_FOR_EACH_TYPED_ARRAY(IMPL_TYPED_ARRAY_CLASS_SPEC)
#undef IMPL_TYPED_ARRAY_CLASS_SPEC
};

// Class definitions for fixed length and resizable typed arrays. Stored into a
// 2-dimensional array to ensure the classes are in contiguous memory.
const JSClass TypedArrayObject::anyClasses[2][Scalar::MaxTypedArrayViewType] = {
    // Class definitions for fixed length typed arrays.
    {
#define IMPL_TYPED_ARRAY_CLASS(ExternalType, NativeType, Name)             \
  {                                                                        \
      #Name "Array",                                                       \
      JSCLASS_HAS_RESERVED_SLOTS(TypedArrayObject::RESERVED_SLOTS) |       \
          JSCLASS_HAS_CACHED_PROTO(JSProto_##Name##Array) |                \
          JSCLASS_DELAY_METADATA_BUILDER | JSCLASS_SKIP_NURSERY_FINALIZE | \
          JSCLASS_BACKGROUND_FINALIZE,                                     \
      &TypedArrayClassOps,                                                 \
      &TypedArrayObjectClassSpecs[Scalar::Type::Name],                     \
      &TypedArrayClassExtension,                                           \
  },

        JS_FOR_EACH_TYPED_ARRAY(IMPL_TYPED_ARRAY_CLASS)
#undef IMPL_TYPED_ARRAY_CLASS
    },

    // Class definitions for resizable typed arrays.
    {
#define IMPL_TYPED_ARRAY_CLASS(ExternalType, NativeType, Name)                \
  {                                                                           \
      #Name "Array",                                                          \
      JSCLASS_HAS_RESERVED_SLOTS(ResizableTypedArrayObject::RESERVED_SLOTS) | \
          JSCLASS_HAS_CACHED_PROTO(JSProto_##Name##Array) |                   \
          JSCLASS_DELAY_METADATA_BUILDER,                                     \
      &ResizableTypedArrayClassOps,                                           \
      &TypedArrayObjectClassSpecs[Scalar::Type::Name],                        \
      JS_NULL_CLASS_EXT,                                                      \
  },

        JS_FOR_EACH_TYPED_ARRAY(IMPL_TYPED_ARRAY_CLASS)
#undef IMPL_TYPED_ARRAY_CLASS
    },
};

const JSClass (
    &TypedArrayObject::fixedLengthClasses)[Scalar::MaxTypedArrayViewType] =
    TypedArrayObject::anyClasses[0];

const JSClass (
    &TypedArrayObject::resizableClasses)[Scalar::MaxTypedArrayViewType] =
    TypedArrayObject::anyClasses[1];

// The various typed array prototypes are supposed to 1) be normal objects,
// 2) stringify to "[object <name of constructor>]", and 3) (Gecko-specific)
// be xrayable.  The first and second requirements mandate (in the absence of
// @@toStringTag) a custom class.  The third requirement mandates that each
// prototype's class have the relevant typed array's cached JSProtoKey in them.
// Thus we need one class with cached prototype per kind of typed array, with a
// delegated ClassSpec.
//
// Actually ({}).toString.call(Uint8Array.prototype) should throw, because
// Uint8Array.prototype lacks the the typed array internal slots.  (Same as
// with %TypedArray%.prototype.)  It's not clear this is desirable (see
// above), but it's what we've always done, so keep doing it till we
// implement @@toStringTag or ES6 changes.
const JSClass TypedArrayObject::protoClasses[Scalar::MaxTypedArrayViewType] = {
#define IMPL_TYPED_ARRAY_PROTO_CLASS(ExternalType, NativeType, Name) \
  {                                                                  \
      #Name "Array.prototype",                                       \
      JSCLASS_HAS_CACHED_PROTO(JSProto_##Name##Array),               \
      JS_NULL_CLASS_OPS,                                             \
      &TypedArrayObjectClassSpecs[Scalar::Type::Name],               \
  },

    JS_FOR_EACH_TYPED_ARRAY(IMPL_TYPED_ARRAY_PROTO_CLASS)
#undef IMPL_TYPED_ARRAY_PROTO_CLASS
};

/* static */
bool TypedArrayObject::isOriginalLengthGetter(Native native) {
  return native == TypedArray_lengthGetter;
}

/* static */
bool TypedArrayObject::isOriginalByteOffsetGetter(Native native) {
  return native == TypedArray_byteOffsetGetter;
}

/* static */
bool TypedArrayObject::isOriginalByteLengthGetter(Native native) {
  return native == TypedArray_byteLengthGetter;
}

bool js::IsTypedArrayConstructor(const JSObject* obj) {
#define CHECK_TYPED_ARRAY_CONSTRUCTOR(_, T, N)                                 \
  if (IsNativeFunction(obj, TypedArrayObjectTemplate<T>::class_constructor)) { \
    return true;                                                               \
  }
  JS_FOR_EACH_TYPED_ARRAY(CHECK_TYPED_ARRAY_CONSTRUCTOR)
#undef CHECK_TYPED_ARRAY_CONSTRUCTOR
  return false;
}

bool js::IsTypedArrayConstructor(HandleValue v, Scalar::Type type) {
  return IsNativeFunction(v, TypedArrayConstructorNative(type));
}

JSNative js::TypedArrayConstructorNative(Scalar::Type type) {
#define TYPED_ARRAY_CONSTRUCTOR_NATIVE(_, T, N)            \
  if (type == Scalar::N) {                                 \
    return TypedArrayObjectTemplate<T>::class_constructor; \
  }
  JS_FOR_EACH_TYPED_ARRAY(TYPED_ARRAY_CONSTRUCTOR_NATIVE)
#undef TYPED_ARRAY_CONSTRUCTOR_NATIVE

  MOZ_CRASH("unexpected typed array type");
}

bool js::IsBufferSource(JSObject* object, SharedMem<uint8_t*>* dataPointer,
                        size_t* byteLength) {
  if (object->is<TypedArrayObject>()) {
    TypedArrayObject& view = object->as<TypedArrayObject>();
    *dataPointer = view.dataPointerEither().cast<uint8_t*>();
    *byteLength = view.byteLength().valueOr(0);
    return true;
  }

  if (object->is<DataViewObject>()) {
    DataViewObject& view = object->as<DataViewObject>();
    *dataPointer = view.dataPointerEither().cast<uint8_t*>();
    *byteLength = view.byteLength().valueOr(0);
    return true;
  }

  if (object->is<ArrayBufferObject>()) {
    ArrayBufferObject& buffer = object->as<ArrayBufferObject>();
    *dataPointer = buffer.dataPointerShared();
    *byteLength = buffer.byteLength();
    return true;
  }

  if (object->is<SharedArrayBufferObject>()) {
    SharedArrayBufferObject& buffer = object->as<SharedArrayBufferObject>();
    *dataPointer = buffer.dataPointerShared();
    *byteLength = buffer.byteLength();
    return true;
  }

  return false;
}

template <typename CharT>
static inline bool StringIsInfinity(mozilla::Range<const CharT> s) {
  static constexpr std::string_view Infinity = "Infinity";

  // Compilers optimize this to one |cmp| instruction on x64 resp. two for x86,
  // when the input is a Latin-1 string, because the string "Infinity" is
  // exactly eight characters long, so it can be represented as a single uint64
  // value.
  return s.length() == Infinity.length() &&
         EqualChars(s.begin().get(), Infinity.data(), Infinity.length());
}

template <typename CharT>
static inline bool StringIsNaN(mozilla::Range<const CharT> s) {
  static constexpr std::string_view NaN = "NaN";

  // "NaN" is not as nicely optimizable as "Infinity", but oh well.
  return s.length() == NaN.length() &&
         EqualChars(s.begin().get(), NaN.data(), NaN.length());
}

template <typename CharT>
static mozilla::Maybe<uint64_t> StringToTypedArrayIndexSlow(
    mozilla::Range<const CharT> s) {
  const mozilla::RangedPtr<const CharT> start = s.begin();
  const mozilla::RangedPtr<const CharT> end = s.end();

  const CharT* actualEnd;
  double result = js_strtod(start.get(), end.get(), &actualEnd);

  // The complete string must have been parsed.
  if (actualEnd != end.get()) {
    return mozilla::Nothing();
  }

  // Now convert it back to a string.
  ToCStringBuf cbuf;
  size_t cstrlen;
  const char* cstr = js::NumberToCString(&cbuf, result, &cstrlen);
  MOZ_ASSERT(cstr);

  // Both strings must be equal for a canonical numeric index string.
  if (s.length() != cstrlen || !EqualChars(start.get(), cstr, cstrlen)) {
    return mozilla::Nothing();
  }

  // Directly perform IsInteger() check and encode negative and non-integer
  // indices as OOB.
  // See 9.4.5.2 [[HasProperty]], steps 3.b.iii and 3.b.v.
  // See 9.4.5.3 [[DefineOwnProperty]], steps 3.b.i and 3.b.iii.
  // See 9.4.5.8 IntegerIndexedElementGet, steps 5 and 8.
  // See 9.4.5.9 IntegerIndexedElementSet, steps 6 and 9.
  if (result < 0 || !IsInteger(result)) {
    return mozilla::Some(UINT64_MAX);
  }

  // Anything equals-or-larger than 2^53 is definitely OOB, encode it
  // accordingly so that the cast to uint64_t is well defined.
  if (result >= DOUBLE_INTEGRAL_PRECISION_LIMIT) {
    return mozilla::Some(UINT64_MAX);
  }

  // The string is an actual canonical numeric index.
  return mozilla::Some(result);
}

template <typename CharT>
mozilla::Maybe<uint64_t> js::StringToTypedArrayIndex(
    mozilla::Range<const CharT> s) {
  mozilla::RangedPtr<const CharT> cp = s.begin();
  const mozilla::RangedPtr<const CharT> end = s.end();

  MOZ_ASSERT(cp < end, "caller must check for empty strings");

  bool negative = false;
  if (*cp == '-') {
    negative = true;
    if (++cp == end) {
      return mozilla::Nothing();
    }
  }

  if (!IsAsciiDigit(*cp)) {
    // Check for "NaN", "Infinity", or "-Infinity".
    if ((!negative && StringIsNaN<CharT>({cp, end})) ||
        StringIsInfinity<CharT>({cp, end})) {
      return mozilla::Some(UINT64_MAX);
    }
    return mozilla::Nothing();
  }

  uint32_t digit = AsciiDigitToNumber(*cp++);

  // Don't allow leading zeros.
  if (digit == 0 && cp != end) {
    // The string may be of the form "0.xyz". The exponent form isn't possible
    // when the string starts with "0".
    if (*cp == '.') {
      return StringToTypedArrayIndexSlow(s);
    }
    return mozilla::Nothing();
  }

  uint64_t index = digit;

  for (; cp < end; cp++) {
    if (!IsAsciiDigit(*cp)) {
      // Take the slow path when the string has fractional parts or an exponent.
      if (*cp == '.' || *cp == 'e') {
        return StringToTypedArrayIndexSlow(s);
      }
      return mozilla::Nothing();
    }

    digit = AsciiDigitToNumber(*cp);

    static_assert(
        uint64_t(DOUBLE_INTEGRAL_PRECISION_LIMIT) < (UINT64_MAX - 10) / 10,
        "2^53 is way below UINT64_MAX, so |10 * index + digit| can't overflow");

    index = 10 * index + digit;

    // Also take the slow path when the string is larger-or-equals 2^53.
    if (index >= uint64_t(DOUBLE_INTEGRAL_PRECISION_LIMIT)) {
      return StringToTypedArrayIndexSlow(s);
    }
  }

  if (negative) {
    return mozilla::Some(UINT64_MAX);
  }
  return mozilla::Some(index);
}

template mozilla::Maybe<uint64_t> js::StringToTypedArrayIndex(
    mozilla::Range<const char16_t> s);

template mozilla::Maybe<uint64_t> js::StringToTypedArrayIndex(
    mozilla::Range<const Latin1Char> s);

bool js::SetTypedArrayElement(JSContext* cx, Handle<TypedArrayObject*> obj,
                              uint64_t index, HandleValue v,
                              ObjectOpResult& result) {
  switch (obj->type()) {
#define SET_TYPED_ARRAY_ELEMENT(_, T, N) \
  case Scalar::N:                        \
    return TypedArrayObjectTemplate<T>::setElement(cx, obj, index, v, result);
    JS_FOR_EACH_TYPED_ARRAY(SET_TYPED_ARRAY_ELEMENT)
#undef SET_TYPED_ARRAY_ELEMENT
    case Scalar::MaxTypedArrayViewType:
    case Scalar::Int64:
    case Scalar::Simd128:
      break;
  }

  MOZ_CRASH("Unsupported TypedArray type");
}

bool js::SetTypedArrayElementOutOfBounds(JSContext* cx,
                                         Handle<TypedArrayObject*> obj,
                                         uint64_t index, HandleValue v,
                                         ObjectOpResult& result) {
  // This method is only called for non-existent properties, which means any
  // absent indexed properties must be out of range. Unless the typed array is
  // backed by a growable SharedArrayBuffer, in which case another thread may
  // have grown the buffer.
  MOZ_ASSERT(index >= obj->length().valueOr(0) ||
             (obj->isSharedMemory() && obj->bufferShared()->isGrowable()));

  // The following steps refer to 10.4.5.16 TypedArraySetElement.

  // Steps 1-2.
  RootedValue converted(cx);
  if (!obj->convertValue(cx, v, &converted)) {
    return false;
  }

  // Step 3.
  if (index < obj->length().valueOr(0)) {
    // Side-effects when converting the value may have put the index in-bounds
    // when the backing buffer is resizable.
    MOZ_ASSERT(obj->hasResizableBuffer());
    return SetTypedArrayElement(cx, obj, index, converted, result);
  }

  // Step 4.
  return result.succeed();
}

// ES2021 draft rev b3f9b5089bcc3ddd8486379015cd11eb1427a5eb
// 9.4.5.3 [[DefineOwnProperty]], step 3.b.
bool js::DefineTypedArrayElement(JSContext* cx, Handle<TypedArrayObject*> obj,
                                 uint64_t index,
                                 Handle<PropertyDescriptor> desc,
                                 ObjectOpResult& result) {
  // These are all substeps of 3.b.

  // Step i.
  if (index >= obj->length().valueOr(0)) {
    if (obj->hasDetachedBuffer()) {
      return result.fail(JSMSG_TYPED_ARRAY_DETACHED);
    }
    return result.fail(JSMSG_DEFINE_BAD_INDEX);
  }

  // Step ii.
  if (desc.isAccessorDescriptor()) {
    return result.fail(JSMSG_CANT_REDEFINE_PROP);
  }

  // Step iii.
  if (desc.hasConfigurable() && !desc.configurable()) {
    return result.fail(JSMSG_CANT_REDEFINE_PROP);
  }

  // Step iv.
  if (desc.hasEnumerable() && !desc.enumerable()) {
    return result.fail(JSMSG_CANT_REDEFINE_PROP);
  }

  // Step v.
  if (desc.hasWritable() && !desc.writable()) {
    return result.fail(JSMSG_CANT_REDEFINE_PROP);
  }

  // Step vi.
  if (desc.hasValue()) {
    switch (obj->type()) {
#define DEFINE_TYPED_ARRAY_ELEMENT(_, T, N)                        \
  case Scalar::N:                                                  \
    return TypedArrayObjectTemplate<T>::setElement(cx, obj, index, \
                                                   desc.value(), result);
      JS_FOR_EACH_TYPED_ARRAY(DEFINE_TYPED_ARRAY_ELEMENT)
#undef DEFINE_TYPED_ARRAY_ELEMENT
      case Scalar::MaxTypedArrayViewType:
      case Scalar::Int64:
      case Scalar::Simd128:
        break;
    }

    MOZ_CRASH("Unsupported TypedArray type");
  }

  // Step vii.
  return result.succeed();
}

template <typename T, typename U>
static constexpr typename std::enable_if_t<std::is_unsigned_v<T>, U>
UnsignedSortValue(U val) {
  return val;
}

template <typename T, typename U>
static constexpr
    typename std::enable_if_t<std::is_integral_v<T> && std::is_signed_v<T>, U>
    UnsignedSortValue(U val) {
  // Flip sign bit.
  return val ^ static_cast<U>(std::numeric_limits<T>::min());
}

template <typename T, typename UnsignedT>
static constexpr
    typename std::enable_if_t<std::is_floating_point_v<T>, UnsignedT>
    UnsignedSortValue(UnsignedT val) {
  // Flip sign bit for positive numbers; flip all bits for negative numbers,
  // except negative NaNs.
  using FloatingPoint = mozilla::FloatingPoint<T>;
  static_assert(std::is_same_v<typename FloatingPoint::Bits, UnsignedT>,
                "FloatingPoint::Bits matches the unsigned int representation");

  // FF80'0000 is negative infinity, (FF80'0000, FFFF'FFFF] are all NaNs with
  // the sign-bit set (and the equivalent holds for double values). So any value
  // larger than negative infinity is a negative NaN.
  constexpr UnsignedT NegativeInfinity =
      FloatingPoint::kSignBit | FloatingPoint::kExponentBits;
  if (val > NegativeInfinity) {
    return val;
  }
  if (val & FloatingPoint::kSignBit) {
    return ~val;
  }
  return val ^ FloatingPoint::kSignBit;
}

template <typename T>
static typename std::enable_if_t<std::is_integral_v<T> ||
                                 std::is_same_v<T, uint8_clamped>>
TypedArrayStdSort(SharedMem<void*> data, size_t length) {
  T* unwrapped = data.cast<T*>().unwrapUnshared();
  std::sort(unwrapped, unwrapped + length);
}

template <typename T>
static typename std::enable_if_t<std::is_floating_point_v<T>> TypedArrayStdSort(
    SharedMem<void*> data, size_t length) {
  // Sort on the unsigned representation for performance reasons.
  using UnsignedT =
      typename mozilla::UnsignedStdintTypeForSize<sizeof(T)>::Type;
  UnsignedT* unwrapped = data.cast<UnsignedT*>().unwrapUnshared();
  std::sort(unwrapped, unwrapped + length, [](UnsignedT x, UnsignedT y) {
    constexpr auto SortValue = UnsignedSortValue<T, UnsignedT>;
    return SortValue(x) < SortValue(y);
  });
}

template <typename T, typename Ops>
static typename std::enable_if_t<std::is_same_v<Ops, UnsharedOps>, bool>
TypedArrayStdSort(JSContext* cx, TypedArrayObject* typedArray, size_t length) {
  TypedArrayStdSort<T>(typedArray->dataPointerEither(), length);
  return true;
}

template <typename T, typename Ops>
static typename std::enable_if_t<std::is_same_v<Ops, SharedOps>, bool>
TypedArrayStdSort(JSContext* cx, TypedArrayObject* typedArray, size_t length) {
  // Always create a copy when sorting shared memory backed typed arrays to
  // ensure concurrent write accesses doesn't lead to UB when calling std::sort.
  auto ptr = cx->make_pod_array<T>(length);
  if (!ptr) {
    return false;
  }
  SharedMem<T*> unshared = SharedMem<T*>::unshared(ptr.get());
  SharedMem<T*> data = typedArray->dataPointerShared().cast<T*>();

  Ops::podCopy(unshared, data, length);

  TypedArrayStdSort<T>(unshared.template cast<void*>(), length);

  Ops::podCopy(data, unshared, length);

  return true;
}

template <typename T, typename Ops>
static bool TypedArrayCountingSort(JSContext* cx, TypedArrayObject* typedArray,
                                   size_t length) {
  static_assert(std::is_integral_v<T> || std::is_same_v<T, uint8_clamped>,
                "Counting sort expects integral array elements");

  // Determined by performance testing.
  if (length <= 64) {
    return TypedArrayStdSort<T, Ops>(cx, typedArray, length);
  }

  // Map signed values onto the unsigned range when storing in buffer.
  using UnsignedT =
      typename mozilla::UnsignedStdintTypeForSize<sizeof(T)>::Type;
  constexpr T min = std::numeric_limits<T>::min();

  constexpr size_t InlineStorage = sizeof(T) == 1 ? 256 : 0;
  Vector<size_t, InlineStorage> buffer(cx);
  if (!buffer.resize(size_t(std::numeric_limits<UnsignedT>::max()) + 1)) {
    return false;
  }

  SharedMem<T*> data = typedArray->dataPointerEither().cast<T*>();

  // Populate the buffer.
  for (size_t i = 0; i < length; i++) {
    T val = Ops::load(data + i);
    buffer[UnsignedT(val - min)]++;
  }

  // Traverse the buffer in order and write back elements to array.
  UnsignedT val = UnsignedT(-1);  // intentional overflow on first increment
  for (size_t i = 0; i < length;) {
    // Invariant: sum(buffer[val:]) == length-i
    size_t j;
    do {
      j = buffer[++val];
    } while (j == 0);

    for (; j > 0; j--) {
      Ops::store(data + i++, T(val + min));
    }
  }

  return true;
}

template <typename T, typename U, typename Ops>
static void SortByColumn(SharedMem<U*> data, size_t length, SharedMem<U*> aux,
                         uint8_t col) {
  static_assert(std::is_unsigned_v<U>, "SortByColumn sorts on unsigned values");
  static_assert(std::is_same_v<Ops, UnsharedOps>,
                "SortByColumn only works on unshared data");

  // |counts| is used to compute the starting index position for each key.
  // Letting counts[0] always be 0, simplifies the transform step below.
  // Example:
  //
  // Computing frequency counts for the input [1 2 1] gives:
  //      0 1 2 3 ... (keys)
  //      0 0 2 1     (frequencies)
  //
  // Transforming frequencies to indexes gives:
  //      0 1 2 3 ... (keys)
  //      0 0 2 3     (indexes)

  constexpr size_t R = 256;

  // Initialize all entries to zero.
  size_t counts[R + 1] = {};

  const auto ByteAtCol = [col](U x) {
    U y = UnsignedSortValue<T, U>(x);
    return static_cast<uint8_t>(y >> (col * 8));
  };

  // Compute frequency counts.
  for (size_t i = 0; i < length; i++) {
    U val = Ops::load(data + i);
    uint8_t b = ByteAtCol(val);
    counts[b + 1]++;
  }

  // Transform counts to indices.
  std::partial_sum(std::begin(counts), std::end(counts), std::begin(counts));

  // Distribute
  for (size_t i = 0; i < length; i++) {
    U val = Ops::load(data + i);
    uint8_t b = ByteAtCol(val);
    size_t j = counts[b]++;
    MOZ_ASSERT(j < length,
               "index is in bounds when |data| can't be modified concurrently");
    UnsharedOps::store(aux + j, val);
  }

  // Copy back
  Ops::podCopy(data, aux, length);
}

template <typename T, typename Ops>
static bool TypedArrayRadixSort(JSContext* cx, TypedArrayObject* typedArray,
                                size_t length) {
  // Determined by performance testing.
  constexpr size_t StdSortMinCutoff = sizeof(T) == 2 ? 64 : 256;

  // Radix sort uses O(n) additional space, limit this space to 64 MB.
  constexpr size_t StdSortMaxCutoff = (64 * 1024 * 1024) / sizeof(T);

  if (length <= StdSortMinCutoff || length >= StdSortMaxCutoff) {
    return TypedArrayStdSort<T, Ops>(cx, typedArray, length);
  }

  if constexpr (sizeof(T) == 2) {
    // Radix sort uses O(n) additional space, so when |n| reaches 2^16, switch
    // over to counting sort to limit the additional space needed to 2^16.
    constexpr size_t CountingSortMaxCutoff = 65536;

    if (length >= CountingSortMaxCutoff) {
      return TypedArrayCountingSort<T, Ops>(cx, typedArray, length);
    }
  }

  using UnsignedT =
      typename mozilla::UnsignedStdintTypeForSize<sizeof(T)>::Type;

  auto ptr = cx->make_zeroed_pod_array<UnsignedT>(length);
  if (!ptr) {
    return false;
  }
  SharedMem<UnsignedT*> aux = SharedMem<UnsignedT*>::unshared(ptr.get());

  SharedMem<UnsignedT*> data =
      typedArray->dataPointerEither().cast<UnsignedT*>();

  // Always create a copy when sorting shared memory backed typed arrays to
  // ensure concurrent write accesses don't lead to computing bad indices.
  SharedMem<UnsignedT*> unshared;
  SharedMem<UnsignedT*> shared;
  UniquePtr<UnsignedT[], JS::FreePolicy> ptrUnshared;
  if constexpr (std::is_same_v<Ops, SharedOps>) {
    ptrUnshared = cx->make_pod_array<UnsignedT>(length);
    if (!ptrUnshared) {
      return false;
    }
    unshared = SharedMem<UnsignedT*>::unshared(ptrUnshared.get());
    shared = data;

    Ops::podCopy(unshared, shared, length);

    data = unshared;
  }

  for (uint8_t col = 0; col < sizeof(UnsignedT); col++) {
    SortByColumn<T, UnsignedT, UnsharedOps>(data, length, aux, col);
  }

  if constexpr (std::is_same_v<Ops, SharedOps>) {
    Ops::podCopy(shared, unshared, length);
  }

  return true;
}

using TypedArraySortFn = bool (*)(JSContext*, TypedArrayObject*, size_t length);

template <typename T, typename Ops>
static constexpr typename std::enable_if_t<sizeof(T) == 1, TypedArraySortFn>
TypedArraySort() {
  return TypedArrayCountingSort<T, Ops>;
}

template <typename T, typename Ops>
static constexpr typename std::enable_if_t<sizeof(T) == 2 || sizeof(T) == 4,
                                           TypedArraySortFn>
TypedArraySort() {
  return TypedArrayRadixSort<T, Ops>;
}

template <typename T, typename Ops>
static constexpr typename std::enable_if_t<sizeof(T) == 8, TypedArraySortFn>
TypedArraySort() {
  return TypedArrayStdSort<T, Ops>;
}

bool js::intrinsic_TypedArrayNativeSort(JSContext* cx, unsigned argc,
                                        Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  MOZ_ASSERT(args.length() == 1);

  TypedArrayObject* typedArray =
      UnwrapAndDowncastValue<TypedArrayObject>(cx, args[0]);
  if (!typedArray) {
    return false;
  }

  auto length = typedArray->length();
  MOZ_RELEASE_ASSERT(length,
                     "TypedArray is neither detached nor out-of-bounds");

  bool isShared = typedArray->isSharedMemory();
  switch (typedArray->type()) {
#define SORT(_, T, N)                                                   \
  case Scalar::N:                                                       \
    if (isShared) {                                                     \
      if (!TypedArraySort<T, SharedOps>()(cx, typedArray, *length)) {   \
        return false;                                                   \
      }                                                                 \
    } else {                                                            \
      if (!TypedArraySort<T, UnsharedOps>()(cx, typedArray, *length)) { \
        return false;                                                   \
      }                                                                 \
    }                                                                   \
    break;
    JS_FOR_EACH_TYPED_ARRAY(SORT)
#undef SORT
    default:
      MOZ_CRASH("Unsupported TypedArray type");
  }

  args.rval().set(args[0]);
  return true;
}

/* JS Public API */

#define IMPL_TYPED_ARRAY_JSAPI_CONSTRUCTORS(ExternalType, NativeType, Name)   \
  JS_PUBLIC_API JSObject* JS_New##Name##Array(JSContext* cx,                  \
                                              size_t nelements) {             \
    return TypedArrayObjectTemplate<NativeType>::fromLength(cx, nelements);   \
  }                                                                           \
                                                                              \
  JS_PUBLIC_API JSObject* JS_New##Name##ArrayFromArray(JSContext* cx,         \
                                                       HandleObject other) {  \
    return TypedArrayObjectTemplate<NativeType>::fromArray(cx, other);        \
  }                                                                           \
                                                                              \
  JS_PUBLIC_API JSObject* JS_New##Name##ArrayWithBuffer(                      \
      JSContext* cx, HandleObject arrayBuffer, size_t byteOffset,             \
      int64_t length) {                                                       \
    return TypedArrayObjectTemplate<NativeType>::fromBuffer(                  \
        cx, arrayBuffer, byteOffset, length);                                 \
  }                                                                           \
                                                                              \
  JS_PUBLIC_API JSObject* js::Unwrap##Name##Array(JSObject* obj) {            \
    obj = obj->maybeUnwrapIf<TypedArrayObject>();                             \
    if (!obj) {                                                               \
      return nullptr;                                                         \
    }                                                                         \
    const JSClass* clasp = obj->getClass();                                   \
    if (clasp != FixedLengthTypedArrayObjectTemplate<                         \
                     NativeType>::instanceClass() &&                          \
        clasp !=                                                              \
            ResizableTypedArrayObjectTemplate<NativeType>::instanceClass()) { \
      return nullptr;                                                         \
    }                                                                         \
    return obj;                                                               \
  }                                                                           \
                                                                              \
  JS_PUBLIC_API ExternalType* JS_Get##Name##ArrayLengthAndData(               \
      JSObject* obj, size_t* length, bool* isSharedMemory,                    \
      const JS::AutoRequireNoGC& nogc) {                                      \
    TypedArrayObject* tarr = obj->maybeUnwrapAs<TypedArrayObject>();          \
    if (!tarr) {                                                              \
      return nullptr;                                                         \
    }                                                                         \
    mozilla::Span<ExternalType> span =                                        \
        JS::TypedArray<JS::Scalar::Name>::fromObject(tarr).getData(           \
            isSharedMemory, nogc);                                            \
    *length = span.Length();                                                  \
    return span.data();                                                       \
  }                                                                           \
                                                                              \
  JS_PUBLIC_API ExternalType* JS_Get##Name##ArrayData(                        \
      JSObject* obj, bool* isSharedMemory, const JS::AutoRequireNoGC& nogc) { \
    size_t length;                                                            \
    return JS_Get##Name##ArrayLengthAndData(obj, &length, isSharedMemory,     \
                                            nogc);                            \
  }                                                                           \
  JS_PUBLIC_API JSObject* JS_GetObjectAs##Name##Array(                        \
      JSObject* obj, size_t* length, bool* isShared, ExternalType** data) {   \
    obj = js::Unwrap##Name##Array(obj);                                       \
    if (!obj) {                                                               \
      return nullptr;                                                         \
    }                                                                         \
    TypedArrayObject* tarr = &obj->as<TypedArrayObject>();                    \
    *length = tarr->length().valueOr(0);                                      \
    *isShared = tarr->isSharedMemory();                                       \
    *data = static_cast<ExternalType*>(tarr->dataPointerEither().unwrap(      \
        /*safe - caller sees isShared flag*/));                               \
    return obj;                                                               \
  }

JS_FOR_EACH_TYPED_ARRAY(IMPL_TYPED_ARRAY_JSAPI_CONSTRUCTORS)
#undef IMPL_TYPED_ARRAY_JSAPI_CONSTRUCTORS

JS_PUBLIC_API bool JS_IsTypedArrayObject(JSObject* obj) {
  return obj->canUnwrapAs<TypedArrayObject>();
}

JS_PUBLIC_API size_t JS_GetTypedArrayLength(JSObject* obj) {
  TypedArrayObject* tarr = obj->maybeUnwrapAs<TypedArrayObject>();
  if (!tarr) {
    return 0;
  }
  return tarr->length().valueOr(0);
}

JS_PUBLIC_API size_t JS_GetTypedArrayByteOffset(JSObject* obj) {
  TypedArrayObject* tarr = obj->maybeUnwrapAs<TypedArrayObject>();
  if (!tarr) {
    return 0;
  }
  return tarr->byteOffset().valueOr(0);
}

JS_PUBLIC_API size_t JS_GetTypedArrayByteLength(JSObject* obj) {
  TypedArrayObject* tarr = obj->maybeUnwrapAs<TypedArrayObject>();
  if (!tarr) {
    return 0;
  }
  return tarr->byteLength().valueOr(0);
}

JS_PUBLIC_API bool JS_GetTypedArraySharedness(JSObject* obj) {
  TypedArrayObject* tarr = obj->maybeUnwrapAs<TypedArrayObject>();
  if (!tarr) {
    return false;
  }
  return tarr->isSharedMemory();
}

JS_PUBLIC_API JS::Scalar::Type JS_GetArrayBufferViewType(JSObject* obj) {
  ArrayBufferViewObject* view = obj->maybeUnwrapAs<ArrayBufferViewObject>();
  if (!view) {
    return Scalar::MaxTypedArrayViewType;
  }

  if (view->is<TypedArrayObject>()) {
    return view->as<TypedArrayObject>().type();
  }
  if (view->is<DataViewObject>()) {
    return Scalar::MaxTypedArrayViewType;
  }
  MOZ_CRASH("invalid ArrayBufferView type");
}

JS_PUBLIC_API size_t JS_MaxMovableTypedArraySize() {
  return FixedLengthTypedArrayObject::INLINE_BUFFER_LIMIT;
}

namespace JS {

const JSClass* const TypedArray_base::fixedLengthClasses =
    TypedArrayObject::fixedLengthClasses;
const JSClass* const TypedArray_base::resizableClasses =
    TypedArrayObject::resizableClasses;

#define INSTANTIATE(ExternalType, NativeType, Name) \
  template class TypedArray<JS::Scalar::Name>;
JS_FOR_EACH_TYPED_ARRAY(INSTANTIATE)
#undef INSTANTIATE

JS::ArrayBufferOrView JS::ArrayBufferOrView::unwrap(JSObject* maybeWrapped) {
  if (!maybeWrapped) {
    return JS::ArrayBufferOrView(nullptr);
  }
  auto* ab = maybeWrapped->maybeUnwrapIf<ArrayBufferObjectMaybeShared>();
  if (ab) {
    return ArrayBufferOrView::fromObject(ab);
  }

  return ArrayBufferView::unwrap(maybeWrapped);
}

bool JS::ArrayBufferOrView::isDetached() const {
  MOZ_ASSERT(obj);
  if (obj->is<ArrayBufferObjectMaybeShared>()) {
    return obj->as<ArrayBufferObjectMaybeShared>().isDetached();
  } else {
    return obj->as<ArrayBufferViewObject>().hasDetachedBuffer();
  }
}

bool JS::ArrayBufferOrView::isResizable() const {
  MOZ_ASSERT(obj);
  if (obj->is<ArrayBufferObjectMaybeShared>()) {
    return obj->as<ArrayBufferObjectMaybeShared>().isResizable();
  } else {
    return obj->as<ArrayBufferViewObject>().hasResizableBuffer();
  }
}

JS::TypedArray_base JS::TypedArray_base::fromObject(JSObject* unwrapped) {
  if (unwrapped && unwrapped->is<TypedArrayObject>()) {
    return TypedArray_base(unwrapped);
  }
  return TypedArray_base(nullptr);
}

// Template getData function for TypedArrays, implemented here because
// it requires internal APIs.
template <JS::Scalar::Type EType>
typename mozilla::Span<typename TypedArray<EType>::DataType>
TypedArray<EType>::getData(bool* isSharedMemory, const AutoRequireNoGC&) {
  using ExternalType = TypedArray<EType>::DataType;
  if (!obj) {
    return nullptr;
  }
  TypedArrayObject* tarr = &obj->as<TypedArrayObject>();
  MOZ_ASSERT(tarr);
  *isSharedMemory = tarr->isSharedMemory();
  return {static_cast<ExternalType*>(tarr->dataPointerEither().unwrap(
              /*safe - caller sees isShared*/)),
          tarr->length().valueOr(0)};
};

// Force the method defined above to actually be instantianted in this
// compilation unit and emitted into the object file, since otherwise a binary
// could include the header file and emit an undefined symbol that would not be
// satisfied by the linker. (This happens with opt gtest, at least. In a DEBUG
// build, the header contains a call to this function so it will always be
// emitted.)
#define INSTANTIATE_GET_DATA(a, b, Name)                                  \
  template mozilla::Span<typename TypedArray<JS::Scalar::Name>::DataType> \
  TypedArray<JS::Scalar::Name>::getData(bool* isSharedMemory,             \
                                        const AutoRequireNoGC&);
JS_FOR_EACH_TYPED_ARRAY(INSTANTIATE_GET_DATA)
#undef INSTANTIATE_GET_DATA

} /* namespace JS */