1 files changed, 908 insertions, 0 deletions

diff --git a/js/src/vm/NativeObject-inl.h b/js/src/vm/NativeObject-inl.h
new file mode 100644
index 0000000000..de43d2dc15
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+++ b/js/src/vm/NativeObject-inl.h
@@ -0,0 +1,908 @@
+/* -*- 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/. */
+
+#ifndef vm_NativeObject_inl_h
+#define vm_NativeObject_inl_h
+
+#include "vm/NativeObject.h"
+
+#include "mozilla/Maybe.h"
+
+#include <type_traits>
+
+#include "gc/Allocator.h"
+#include "gc/GCProbes.h"
+#include "gc/MaybeRooted.h"
+#include "js/friend/ErrorMessages.h"  // js::GetErrorMessage, JSMSG_*
+#include "vm/Compartment.h"
+#include "vm/Iteration.h"
+#include "vm/JSContext.h"
+#include "vm/PlainObject.h"
+#include "vm/PropertyResult.h"
+#include "vm/TypedArrayObject.h"
+
+#include "gc/Heap-inl.h"
+#include "gc/Marking-inl.h"
+#include "gc/ObjectKind-inl.h"
+#include "vm/Compartment-inl.h"
+#include "vm/JSObject-inl.h"
+#include "vm/Realm-inl.h"
+#include "vm/Shape-inl.h"
+
+#ifdef ENABLE_RECORD_TUPLE
+// Defined in vm/RecordTupleShared.{h,cpp}. We cannot include that file
+// because it causes circular dependencies.
+extern bool js::IsExtendedPrimitive(const JSObject& obj);
+#endif
+
+namespace js {
+
+constexpr ObjectSlots::ObjectSlots(uint32_t capacity,
+                                   uint32_t dictionarySlotSpan,
+                                   uint64_t maybeUniqueId)
+    : capacity_(capacity),
+      dictionarySlotSpan_(dictionarySlotSpan),
+      maybeUniqueId_(maybeUniqueId) {
+  MOZ_ASSERT(this->capacity() == capacity);
+  MOZ_ASSERT(this->dictionarySlotSpan() == dictionarySlotSpan);
+}
+
+inline uint32_t NativeObject::numFixedSlotsMaybeForwarded() const {
+  return gc::MaybeForwarded(JSObject::shape())->asNative().numFixedSlots();
+}
+
+inline uint8_t* NativeObject::fixedData(size_t nslots) const {
+  MOZ_ASSERT(ClassCanHaveFixedData(gc::MaybeForwardedObjectClass(this)));
+  MOZ_ASSERT(nslots == numFixedSlotsMaybeForwarded());
+  return reinterpret_cast<uint8_t*>(&fixedSlots()[nslots]);
+}
+
+inline void NativeObject::initDenseElementHole(uint32_t index) {
+  markDenseElementsNotPacked();
+  initDenseElementUnchecked(index, MagicValue(JS_ELEMENTS_HOLE));
+}
+
+inline void NativeObject::setDenseElementHole(uint32_t index) {
+  markDenseElementsNotPacked();
+  setDenseElementUnchecked(index, MagicValue(JS_ELEMENTS_HOLE));
+}
+
+inline void NativeObject::removeDenseElementForSparseIndex(uint32_t index) {
+  MOZ_ASSERT(containsPure(PropertyKey::Int(index)));
+  if (containsDenseElement(index)) {
+    setDenseElementHole(index);
+  }
+}
+
+inline void NativeObject::markDenseElementsNotPacked() {
+  MOZ_ASSERT(is<NativeObject>());
+  getElementsHeader()->markNonPacked();
+}
+
+inline void NativeObject::elementsRangePostWriteBarrier(uint32_t start,
+                                                        uint32_t count) {
+  if (!isTenured()) {
+    return;
+  }
+  for (size_t i = 0; i < count; i++) {
+    const Value& v = elements_[start + i];
+    if (v.isGCThing()) {
+      if (gc::StoreBuffer* sb = v.toGCThing()->storeBuffer()) {
+        sb->putSlot(this, HeapSlot::Element, unshiftedIndex(start + i),
+                    count - i);
+        return;
+      }
+    }
+  }
+}
+
+inline void NativeObject::copyDenseElements(uint32_t dstStart, const Value* src,
+                                            uint32_t count) {
+  MOZ_ASSERT(dstStart + count <= getDenseCapacity());
+  MOZ_ASSERT(isExtensible());
+  MOZ_ASSERT_IF(count > 0, src != nullptr);
+#ifdef DEBUG
+  for (uint32_t i = 0; i < count; ++i) {
+    checkStoredValue(src[i]);
+  }
+#endif
+  if (count == 0) {
+    return;
+  }
+  if (zone()->needsIncrementalBarrier()) {
+    uint32_t numShifted = getElementsHeader()->numShiftedElements();
+    for (uint32_t i = 0; i < count; ++i) {
+      elements_[dstStart + i].set(this, HeapSlot::Element,
+                                  dstStart + i + numShifted, src[i]);
+    }
+  } else {
+    memcpy(reinterpret_cast<Value*>(&elements_[dstStart]), src,
+           count * sizeof(Value));
+    elementsRangePostWriteBarrier(dstStart, count);
+  }
+}
+
+inline void NativeObject::initDenseElements(NativeObject* src,
+                                            uint32_t srcStart, uint32_t count) {
+  MOZ_ASSERT(src->getDenseInitializedLength() >= srcStart + count);
+
+  const Value* vp = src->getDenseElements() + srcStart;
+
+  if (!src->denseElementsArePacked()) {
+    // Mark non-packed if we're copying holes or if there are too many elements
+    // to check this efficiently.
+    static constexpr uint32_t MaxCountForPackedCheck = 30;
+    if (count > MaxCountForPackedCheck) {
+      markDenseElementsNotPacked();
+    } else {
+      for (uint32_t i = 0; i < count; i++) {
+        if (vp[i].isMagic(JS_ELEMENTS_HOLE)) {
+          markDenseElementsNotPacked();
+          break;
+        }
+      }
+    }
+  }
+
+  initDenseElements(vp, count);
+}
+
+inline void NativeObject::initDenseElements(const Value* src, uint32_t count) {
+  MOZ_ASSERT(getDenseInitializedLength() == 0);
+  MOZ_ASSERT(count <= getDenseCapacity());
+  MOZ_ASSERT(src);
+  MOZ_ASSERT(isExtensible());
+
+  setDenseInitializedLength(count);
+
+#ifdef DEBUG
+  for (uint32_t i = 0; i < count; ++i) {
+    checkStoredValue(src[i]);
+  }
+#endif
+
+  memcpy(reinterpret_cast<Value*>(elements_), src, count * sizeof(Value));
+  elementsRangePostWriteBarrier(0, count);
+}
+
+inline void NativeObject::initDenseElementRange(uint32_t destStart,
+                                                NativeObject* src,
+                                                uint32_t count) {
+  MOZ_ASSERT(count <= src->getDenseInitializedLength());
+
+  // The initialized length must already be set to the correct value.
+  MOZ_ASSERT(destStart + count == getDenseInitializedLength());
+
+  if (!src->denseElementsArePacked()) {
+    markDenseElementsNotPacked();
+  }
+
+  const Value* vp = src->getDenseElements();
+#ifdef DEBUG
+  for (uint32_t i = 0; i < count; ++i) {
+    checkStoredValue(vp[i]);
+  }
+#endif
+  memcpy(reinterpret_cast<Value*>(elements_) + destStart, vp,
+         count * sizeof(Value));
+  elementsRangePostWriteBarrier(destStart, count);
+}
+
+template <typename Iter>
+inline bool NativeObject::initDenseElementsFromRange(JSContext* cx, Iter begin,
+                                                     Iter end) {
+  // This method populates the elements of a particular Array that's an
+  // internal implementation detail of GeneratorObject. Failing any of the
+  // following means the Array has escaped and/or been mistreated.
+  MOZ_ASSERT(isExtensible());
+  MOZ_ASSERT(!isIndexed());
+  MOZ_ASSERT(is<ArrayObject>());
+  MOZ_ASSERT(as<ArrayObject>().lengthIsWritable());
+  MOZ_ASSERT(!denseElementsAreFrozen());
+  MOZ_ASSERT(getElementsHeader()->numShiftedElements() == 0);
+
+  MOZ_ASSERT(getDenseInitializedLength() == 0);
+
+  auto size = end - begin;
+  uint32_t count = uint32_t(size);
+  MOZ_ASSERT(count <= uint32_t(INT32_MAX));
+  if (count > getDenseCapacity()) {
+    if (!growElements(cx, count)) {
+      return false;
+    }
+  }
+
+  HeapSlot* sp = elements_;
+  size_t slot = 0;
+  for (; begin != end; sp++, begin++) {
+    Value v = *begin;
+#ifdef DEBUG
+    checkStoredValue(v);
+#endif
+    sp->init(this, HeapSlot::Element, slot++, v);
+  }
+  MOZ_ASSERT(slot == count);
+
+  getElementsHeader()->initializedLength = count;
+  as<ArrayObject>().setLength(count);
+  return true;
+}
+
+inline bool NativeObject::tryShiftDenseElements(uint32_t count) {
+  MOZ_ASSERT(isExtensible());
+
+  ObjectElements* header = getElementsHeader();
+  if (header->initializedLength == count ||
+      count > ObjectElements::MaxShiftedElements ||
+      header->hasNonwritableArrayLength()) {
+    return false;
+  }
+
+  shiftDenseElementsUnchecked(count);
+  return true;
+}
+
+inline void NativeObject::shiftDenseElementsUnchecked(uint32_t count) {
+  MOZ_ASSERT(isExtensible());
+
+  ObjectElements* header = getElementsHeader();
+  MOZ_ASSERT(count > 0);
+  MOZ_ASSERT(count < header->initializedLength);
+
+  if (MOZ_UNLIKELY(header->numShiftedElements() + count >
+                   ObjectElements::MaxShiftedElements)) {
+    moveShiftedElements();
+    header = getElementsHeader();
+  }
+
+  prepareElementRangeForOverwrite(0, count);
+  header->addShiftedElements(count);
+
+  elements_ += count;
+  ObjectElements* newHeader = getElementsHeader();
+  memmove(newHeader, header, sizeof(ObjectElements));
+}
+
+inline void NativeObject::moveDenseElements(uint32_t dstStart,
+                                            uint32_t srcStart, uint32_t count) {
+  MOZ_ASSERT(dstStart + count <= getDenseCapacity());
+  MOZ_ASSERT(srcStart + count <= getDenseInitializedLength());
+  MOZ_ASSERT(isExtensible());
+
+  /*
+   * Using memmove here would skip write barriers. Also, we need to consider
+   * an array containing [A, B, C], in the following situation:
+   *
+   * 1. Incremental GC marks slot 0 of array (i.e., A), then returns to JS code.
+   * 2. JS code moves slots 1..2 into slots 0..1, so it contains [B, C, C].
+   * 3. Incremental GC finishes by marking slots 1 and 2 (i.e., C).
+   *
+   * Since normal marking never happens on B, it is very important that the
+   * write barrier is invoked here on B, despite the fact that it exists in
+   * the array before and after the move.
+   */
+  if (zone()->needsIncrementalBarrier()) {
+    uint32_t numShifted = getElementsHeader()->numShiftedElements();
+    if (dstStart < srcStart) {
+      HeapSlot* dst = elements_ + dstStart;
+      HeapSlot* src = elements_ + srcStart;
+      for (uint32_t i = 0; i < count; i++, dst++, src++) {
+        dst->set(this, HeapSlot::Element, dst - elements_ + numShifted, *src);
+      }
+    } else {
+      HeapSlot* dst = elements_ + dstStart + count - 1;
+      HeapSlot* src = elements_ + srcStart + count - 1;
+      for (uint32_t i = 0; i < count; i++, dst--, src--) {
+        dst->set(this, HeapSlot::Element, dst - elements_ + numShifted, *src);
+      }
+    }
+  } else {
+    memmove(elements_ + dstStart, elements_ + srcStart,
+            count * sizeof(HeapSlot));
+    elementsRangePostWriteBarrier(dstStart, count);
+  }
+}
+
+inline void NativeObject::reverseDenseElementsNoPreBarrier(uint32_t length) {
+  MOZ_ASSERT(!zone()->needsIncrementalBarrier());
+
+  MOZ_ASSERT(isExtensible());
+
+  MOZ_ASSERT(length > 1);
+  MOZ_ASSERT(length <= getDenseInitializedLength());
+
+  Value* valLo = reinterpret_cast<Value*>(elements_);
+  Value* valHi = valLo + (length - 1);
+  MOZ_ASSERT(valLo < valHi);
+
+  do {
+    Value origLo = *valLo;
+    *valLo = *valHi;
+    *valHi = origLo;
+    ++valLo;
+    --valHi;
+  } while (valLo < valHi);
+
+  elementsRangePostWriteBarrier(0, length);
+}
+
+inline void NativeObject::ensureDenseInitializedLength(uint32_t index,
+                                                       uint32_t extra) {
+  // Ensure that the array's contents have been initialized up to index, and
+  // mark the elements through 'index + extra' as initialized in preparation
+  // for a write.
+
+  MOZ_ASSERT(!denseElementsAreFrozen());
+  MOZ_ASSERT(isExtensible() || (containsDenseElement(index) && extra == 1));
+  MOZ_ASSERT(index + extra <= getDenseCapacity());
+
+  uint32_t initlen = getDenseInitializedLength();
+  if (index + extra <= initlen) {
+    return;
+  }
+
+  MOZ_ASSERT(isExtensible());
+
+  if (index > initlen) {
+    markDenseElementsNotPacked();
+  }
+
+  uint32_t numShifted = getElementsHeader()->numShiftedElements();
+  size_t offset = initlen;
+  for (HeapSlot* sp = elements_ + initlen; sp != elements_ + (index + extra);
+       sp++, offset++) {
+    sp->init(this, HeapSlot::Element, offset + numShifted,
+             MagicValue(JS_ELEMENTS_HOLE));
+  }
+
+  getElementsHeader()->initializedLength = index + extra;
+}
+
+DenseElementResult NativeObject::extendDenseElements(JSContext* cx,
+                                                     uint32_t requiredCapacity,
+                                                     uint32_t extra) {
+  MOZ_ASSERT(isExtensible());
+
+  /*
+   * Don't grow elements for objects which already have sparse indexes.
+   * This avoids needing to count non-hole elements in willBeSparseElements
+   * every time a new index is added.
+   */
+  if (isIndexed()) {
+    return DenseElementResult::Incomplete;
+  }
+
+  /*
+   * We use the extra argument also as a hint about number of non-hole
+   * elements to be inserted.
+   */
+  if (requiredCapacity > MIN_SPARSE_INDEX &&
+      willBeSparseElements(requiredCapacity, extra)) {
+    return DenseElementResult::Incomplete;
+  }
+
+  if (!growElements(cx, requiredCapacity)) {
+    return DenseElementResult::Failure;
+  }
+
+  return DenseElementResult::Success;
+}
+
+inline DenseElementResult NativeObject::ensureDenseElements(JSContext* cx,
+                                                            uint32_t index,
+                                                            uint32_t extra) {
+  MOZ_ASSERT(is<NativeObject>());
+  MOZ_ASSERT(isExtensible() || (containsDenseElement(index) && extra == 1));
+
+  uint32_t requiredCapacity;
+  if (extra == 1) {
+    /* Optimize for the common case. */
+    if (index < getDenseCapacity()) {
+      ensureDenseInitializedLength(index, 1);
+      return DenseElementResult::Success;
+    }
+    requiredCapacity = index + 1;
+    if (requiredCapacity == 0) {
+      /* Overflow. */
+      return DenseElementResult::Incomplete;
+    }
+  } else {
+    requiredCapacity = index + extra;
+    if (requiredCapacity < index) {
+      /* Overflow. */
+      return DenseElementResult::Incomplete;
+    }
+    if (requiredCapacity <= getDenseCapacity()) {
+      ensureDenseInitializedLength(index, extra);
+      return DenseElementResult::Success;
+    }
+  }
+
+  DenseElementResult result = extendDenseElements(cx, requiredCapacity, extra);
+  if (result != DenseElementResult::Success) {
+    return result;
+  }
+
+  ensureDenseInitializedLength(index, extra);
+  return DenseElementResult::Success;
+}
+
+inline DenseElementResult NativeObject::setOrExtendDenseElements(
+    JSContext* cx, uint32_t start, const Value* vp, uint32_t count) {
+  if (!isExtensible()) {
+    return DenseElementResult::Incomplete;
+  }
+
+  if (is<ArrayObject>() && !as<ArrayObject>().lengthIsWritable() &&
+      start + count >= as<ArrayObject>().length()) {
+    return DenseElementResult::Incomplete;
+  }
+
+  DenseElementResult result = ensureDenseElements(cx, start, count);
+  if (result != DenseElementResult::Success) {
+    return result;
+  }
+
+  if (is<ArrayObject>() && start + count >= as<ArrayObject>().length()) {
+    as<ArrayObject>().setLength(start + count);
+  }
+
+  copyDenseElements(start, vp, count);
+  return DenseElementResult::Success;
+}
+
+inline bool NativeObject::isInWholeCellBuffer() const {
+  const gc::TenuredCell* cell = &asTenured();
+  gc::ArenaCellSet* cells = cell->arena()->bufferedCells();
+  return cells && cells->hasCell(cell);
+}
+
+/* static */
+inline NativeObject* NativeObject::create(
+    JSContext* cx, js::gc::AllocKind kind, js::gc::Heap heap,
+    js::Handle<SharedShape*> shape, js::gc::AllocSite* site /* = nullptr */) {
+  debugCheckNewObject(shape, kind, heap);
+
+  const JSClass* clasp = shape->getObjectClass();
+  MOZ_ASSERT(clasp->isNativeObject());
+  MOZ_ASSERT(!clasp->isJSFunction(), "should use JSFunction::create");
+  MOZ_ASSERT(clasp != &ArrayObject::class_, "should use ArrayObject::create");
+
+  const uint32_t nfixed = shape->numFixedSlots();
+  const uint32_t slotSpan = shape->slotSpan();
+  const size_t nDynamicSlots = calculateDynamicSlots(nfixed, slotSpan, clasp);
+
+  NativeObject* nobj = cx->newCell<NativeObject>(kind, heap, clasp, site);
+  if (!nobj) {
+    return nullptr;
+  }
+
+  nobj->initShape(shape);
+  nobj->setEmptyElements();
+
+  if (!nDynamicSlots) {
+    nobj->initEmptyDynamicSlots();
+  } else if (!nobj->allocateInitialSlots(cx, nDynamicSlots)) {
+    return nullptr;
+  }
+
+  if (slotSpan > 0) {
+    nobj->initSlots(nfixed, slotSpan);
+  }
+
+  if (MOZ_UNLIKELY(cx->realm()->hasAllocationMetadataBuilder())) {
+    if (clasp->shouldDelayMetadataBuilder()) {
+      cx->realm()->setObjectPendingMetadata(nobj);
+    } else {
+      nobj = SetNewObjectMetadata(cx, nobj);
+    }
+  }
+
+  js::gc::gcprobes::CreateObject(nobj);
+
+  return nobj;
+}
+
+MOZ_ALWAYS_INLINE void NativeObject::initEmptyDynamicSlots() {
+  setEmptyDynamicSlots(0);
+}
+
+MOZ_ALWAYS_INLINE void NativeObject::setDictionaryModeSlotSpan(uint32_t span) {
+  MOZ_ASSERT(inDictionaryMode());
+
+  if (!hasDynamicSlots()) {
+    setEmptyDynamicSlots(span);
+    return;
+  }
+
+  getSlotsHeader()->setDictionarySlotSpan(span);
+}
+
+MOZ_ALWAYS_INLINE void NativeObject::setEmptyDynamicSlots(
+    uint32_t dictionarySlotSpan) {
+  MOZ_ASSERT_IF(!inDictionaryMode(), dictionarySlotSpan == 0);
+  MOZ_ASSERT(dictionarySlotSpan <= MAX_FIXED_SLOTS);
+
+  slots_ = emptyObjectSlotsForDictionaryObject[dictionarySlotSpan];
+
+  MOZ_ASSERT(getSlotsHeader()->capacity() == 0);
+  MOZ_ASSERT(getSlotsHeader()->dictionarySlotSpan() == dictionarySlotSpan);
+  MOZ_ASSERT(!hasDynamicSlots());
+  MOZ_ASSERT(!hasUniqueId());
+}
+
+MOZ_ALWAYS_INLINE bool NativeObject::setShapeAndAddNewSlots(
+    JSContext* cx, SharedShape* newShape, uint32_t oldSpan, uint32_t newSpan) {
+  MOZ_ASSERT(!inDictionaryMode());
+  MOZ_ASSERT(newShape->isShared());
+  MOZ_ASSERT(newShape->zone() == zone());
+  MOZ_ASSERT(newShape->numFixedSlots() == numFixedSlots());
+  MOZ_ASSERT(newShape->getObjectClass() == getClass());
+
+  MOZ_ASSERT(oldSpan < newSpan);
+  MOZ_ASSERT(sharedShape()->slotSpan() == oldSpan);
+  MOZ_ASSERT(newShape->slotSpan() == newSpan);
+
+  uint32_t numFixed = newShape->numFixedSlots();
+  if (newSpan > numFixed) {
+    uint32_t oldCapacity = numDynamicSlots();
+    uint32_t newCapacity =
+        calculateDynamicSlots(numFixed, newSpan, newShape->getObjectClass());
+    MOZ_ASSERT(oldCapacity <= newCapacity);
+
+    if (oldCapacity < newCapacity) {
+      if (MOZ_UNLIKELY(!growSlots(cx, oldCapacity, newCapacity))) {
+        return false;
+      }
+    }
+  }
+
+  // Initialize slots [oldSpan, newSpan). Use the *Unchecked version because
+  // the shape's slot span does not reflect the allocated slots at this
+  // point.
+  auto initRange = [](HeapSlot* start, HeapSlot* end) {
+    for (HeapSlot* slot = start; slot < end; slot++) {
+      slot->initAsUndefined();
+    }
+  };
+  forEachSlotRangeUnchecked(oldSpan, newSpan, initRange);
+
+  setShape(newShape);
+  return true;
+}
+
+MOZ_ALWAYS_INLINE bool NativeObject::setShapeAndAddNewSlot(
+    JSContext* cx, SharedShape* newShape, uint32_t slot) {
+  MOZ_ASSERT(!inDictionaryMode());
+  MOZ_ASSERT(newShape->isShared());
+  MOZ_ASSERT(newShape->zone() == zone());
+  MOZ_ASSERT(newShape->numFixedSlots() == numFixedSlots());
+
+  MOZ_ASSERT(newShape->base() == shape()->base());
+  MOZ_ASSERT(newShape->slotSpan() == sharedShape()->slotSpan() + 1);
+  MOZ_ASSERT(newShape->slotSpan() == slot + 1);
+
+  uint32_t numFixed = newShape->numFixedSlots();
+  if (slot < numFixed) {
+    initFixedSlot(slot, UndefinedValue());
+  } else {
+    uint32_t dynamicSlotIndex = slot - numFixed;
+    if (dynamicSlotIndex >= numDynamicSlots()) {
+      if (MOZ_UNLIKELY(!growSlotsForNewSlot(cx, numFixed, slot))) {
+        return false;
+      }
+    }
+    initDynamicSlot(numFixed, slot, UndefinedValue());
+  }
+
+  setShape(newShape);
+  return true;
+}
+
+inline js::gc::AllocKind NativeObject::allocKindForTenure() const {
+  using namespace js::gc;
+  AllocKind kind = GetGCObjectFixedSlotsKind(numFixedSlots());
+  MOZ_ASSERT(!IsBackgroundFinalized(kind));
+  if (!CanChangeToBackgroundAllocKind(kind, getClass())) {
+    return kind;
+  }
+  return ForegroundToBackgroundAllocKind(kind);
+}
+
+inline js::GlobalObject& NativeObject::global() const { return nonCCWGlobal(); }
+
+inline bool NativeObject::denseElementsHaveMaybeInIterationFlag() {
+  if (!getElementsHeader()->maybeInIteration()) {
+    AssertDenseElementsNotIterated(this);
+    return false;
+  }
+  return true;
+}
+
+inline bool NativeObject::denseElementsMaybeInIteration() {
+  if (!denseElementsHaveMaybeInIterationFlag()) {
+    return false;
+  }
+  return compartment()->objectMaybeInIteration(this);
+}
+
+/*
+ * Call obj's resolve hook.
+ *
+ * cx and id are the parameters initially passed to the ongoing lookup;
+ * propp and recursedp are its out parameters.
+ *
+ * There are four possible outcomes:
+ *
+ *  - On failure, report an error or exception and return false.
+ *
+ *  - If we are already resolving a property of obj, call setRecursiveResolve on
+ *    propp and return true.
+ *
+ *  - If the resolve hook finds or defines the sought property, set propp
+ *    appropriately, and return true.
+ *
+ *  - Otherwise no property was resolved. Set propp to NotFound and return true.
+ */
+static MOZ_ALWAYS_INLINE bool CallResolveOp(JSContext* cx,
+                                            Handle<NativeObject*> obj,
+                                            HandleId id,
+                                            PropertyResult* propp) {
+  MOZ_ASSERT(!cx->isHelperThreadContext());
+
+  // Avoid recursion on (obj, id) already being resolved on cx.
+  AutoResolving resolving(cx, obj, id);
+  if (resolving.alreadyStarted()) {
+    // Already resolving id in obj, suppress recursion.
+    propp->setRecursiveResolve();
+    return true;
+  }
+
+  bool resolved = false;
+  AutoRealm ar(cx, obj);
+  if (!obj->getClass()->getResolve()(cx, obj, id, &resolved)) {
+    return false;
+  }
+
+  if (!resolved) {
+    propp->setNotFound();
+    return true;
+  }
+
+  // Assert the mayResolve hook, if there is one, returns true for this
+  // property.
+  MOZ_ASSERT_IF(obj->getClass()->getMayResolve(),
+                obj->getClass()->getMayResolve()(cx->names(), id, obj));
+
+  if (id.isInt()) {
+    uint32_t index = id.toInt();
+    if (obj->containsDenseElement(index)) {
+      propp->setDenseElement(index);
+      return true;
+    }
+  }
+
+  MOZ_ASSERT(!obj->is<TypedArrayObject>());
+
+  mozilla::Maybe<PropertyInfo> prop = obj->lookup(cx, id);
+  if (prop.isSome()) {
+    propp->setNativeProperty(*prop);
+  } else {
+    propp->setNotFound();
+  }
+
+  return true;
+}
+
+enum class LookupResolveMode {
+  IgnoreResolve,
+  CheckResolve,
+  CheckMayResolve,
+};
+
+template <AllowGC allowGC,
+          LookupResolveMode resolveMode = LookupResolveMode::CheckResolve>
+static MOZ_ALWAYS_INLINE bool NativeLookupOwnPropertyInline(
+    JSContext* cx, typename MaybeRooted<NativeObject*, allowGC>::HandleType obj,
+    typename MaybeRooted<jsid, allowGC>::HandleType id, PropertyResult* propp) {
+  // Native objects should should avoid `lookupProperty` hooks, and those that
+  // use them should avoid recursively triggering lookup, and those that still
+  // violate this guidance are the ModuleEnvironmentObject.
+  MOZ_ASSERT_IF(obj->getOpsLookupProperty(),
+                obj->template is<ModuleEnvironmentObject>());
+#ifdef ENABLE_RECORD_TUPLE
+  MOZ_ASSERT(!js::IsExtendedPrimitive(*obj));
+#endif
+
+  // Check for a native dense element.
+  if (id.isInt()) {
+    uint32_t index = id.toInt();
+    if (obj->containsDenseElement(index)) {
+      propp->setDenseElement(index);
+      return true;
+    }
+  }
+
+  // Check for a typed array element. Integer lookups always finish here
+  // so that integer properties on the prototype are ignored even for out
+  // of bounds accesses.
+  if (obj->template is<TypedArrayObject>()) {
+    if (mozilla::Maybe<uint64_t> index = ToTypedArrayIndex(id)) {
+      uint64_t idx = index.value();
+      if (idx < obj->template as<TypedArrayObject>().length()) {
+        propp->setTypedArrayElement(idx);
+      } else {
+        propp->setTypedArrayOutOfRange();
+      }
+      return true;
+    }
+  }
+
+  MOZ_ASSERT(cx->compartment() == obj->compartment());
+
+  // Check for a native property. Call Shape::lookup directly (instead of
+  // NativeObject::lookup) because it's inlined.
+  uint32_t index;
+  if (PropMap* map = obj->shape()->lookup(cx, id, &index)) {
+    propp->setNativeProperty(map->getPropertyInfo(index));
+    return true;
+  }
+
+  // Some callers explicitily want us to ignore the resolve hook entirely. In
+  // that case, we report the property as NotFound.
+  if constexpr (resolveMode == LookupResolveMode::IgnoreResolve) {
+    propp->setNotFound();
+    return true;
+  }
+
+  // JITs in particular use the `mayResolve` hook to determine a JSClass can
+  // never resolve this property name (for all instances of the class).
+  if constexpr (resolveMode == LookupResolveMode::CheckMayResolve) {
+    static_assert(allowGC == false,
+                  "CheckMayResolve can only be used with NoGC");
+
+    MOZ_ASSERT(propp->isNotFound());
+    return !ClassMayResolveId(cx->names(), obj->getClass(), id, obj);
+  }
+
+  MOZ_ASSERT(resolveMode == LookupResolveMode::CheckResolve);
+
+  // If there is no resolve hook, the property definitely does not exist.
+  if (obj->getClass()->getResolve()) {
+    if constexpr (!allowGC) {
+      return false;
+    } else {
+      return CallResolveOp(cx, obj, id, propp);
+    }
+  }
+
+  propp->setNotFound();
+  return true;
+}
+
+/*
+ * Simplified version of NativeLookupOwnPropertyInline that doesn't call
+ * resolve hooks.
+ */
+[[nodiscard]] static inline bool NativeLookupOwnPropertyNoResolve(
+    JSContext* cx, NativeObject* obj, jsid id, PropertyResult* result) {
+  return NativeLookupOwnPropertyInline<NoGC, LookupResolveMode::IgnoreResolve>(
+      cx, obj, id, result);
+}
+
+template <AllowGC allowGC,
+          LookupResolveMode resolveMode = LookupResolveMode::CheckResolve>
+static MOZ_ALWAYS_INLINE bool NativeLookupPropertyInline(
+    JSContext* cx, typename MaybeRooted<NativeObject*, allowGC>::HandleType obj,
+    typename MaybeRooted<jsid, allowGC>::HandleType id,
+    typename MaybeRooted<
+        std::conditional_t<allowGC == AllowGC::CanGC, JSObject*, NativeObject*>,
+        allowGC>::MutableHandleType objp,
+    PropertyResult* propp) {
+  /* Search scopes starting with obj and following the prototype link. */
+  typename MaybeRooted<NativeObject*, allowGC>::RootType current(cx, obj);
+
+  while (true) {
+    if (!NativeLookupOwnPropertyInline<allowGC, resolveMode>(cx, current, id,
+                                                             propp)) {
+      return false;
+    }
+
+    if (propp->isFound()) {
+      objp.set(current);
+      return true;
+    }
+
+    if (propp->shouldIgnoreProtoChain()) {
+      break;
+    }
+
+    JSObject* proto = current->staticPrototype();
+    if (!proto) {
+      break;
+    }
+
+    // If a `lookupProperty` hook exists, recurse into LookupProperty, otherwise
+    // we can simply loop within this call frame.
+    if (proto->getOpsLookupProperty()) {
+      if constexpr (allowGC) {
+        MOZ_ASSERT(!cx->isHelperThreadContext());
+        RootedObject protoRoot(cx, proto);
+        return LookupProperty(cx, protoRoot, id, objp, propp);
+      } else {
+        return false;
+      }
+    }
+
+    current = &proto->as<NativeObject>();
+  }
+
+  MOZ_ASSERT(propp->isNotFound());
+  objp.set(nullptr);
+  return true;
+}
+
+inline bool ThrowIfNotConstructing(JSContext* cx, const CallArgs& args,
+                                   const char* builtinName) {
+  if (args.isConstructing()) {
+    return true;
+  }
+  JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                            JSMSG_BUILTIN_CTOR_NO_NEW, builtinName);
+  return false;
+}
+
+inline bool IsPackedArray(JSObject* obj) {
+  if (!obj->is<ArrayObject>()) {
+    return false;
+  }
+
+  ArrayObject* arr = &obj->as<ArrayObject>();
+  if (arr->getDenseInitializedLength() != arr->length()) {
+    return false;
+  }
+
+  if (!arr->denseElementsArePacked()) {
+    return false;
+  }
+
+#ifdef DEBUG
+  // Assert correctness of the NON_PACKED flag by checking the first few
+  // elements don't contain holes.
+  uint32_t numToCheck = std::min<uint32_t>(5, arr->getDenseInitializedLength());
+  for (uint32_t i = 0; i < numToCheck; i++) {
+    MOZ_ASSERT(!arr->getDenseElement(i).isMagic(JS_ELEMENTS_HOLE));
+  }
+#endif
+
+  return true;
+}
+
+// Like AddDataProperty but optimized for plain objects. Plain objects don't
+// have an addProperty hook.
+MOZ_ALWAYS_INLINE bool AddDataPropertyToPlainObject(
+    JSContext* cx, Handle<PlainObject*> obj, HandleId id, HandleValue v,
+    uint32_t* resultSlot = nullptr) {
+  MOZ_ASSERT(!id.isInt());
+
+  uint32_t slot;
+  if (!resultSlot) {
+    resultSlot = &slot;
+  }
+  if (!NativeObject::addProperty(
+          cx, obj, id, PropertyFlags::defaultDataPropFlags, resultSlot)) {
+    return false;
+  }
+
+  obj->initSlot(*resultSlot, v);
+
+  MOZ_ASSERT(!obj->getClass()->getAddProperty());
+  return true;
+}
+
+}  // namespace js
+
+#endif /* vm_NativeObject_inl_h */