Add m-esr52 at 52.6.0

1 files changed, 840 insertions, 0 deletions

diff --git a/js/src/vm/UnboxedObject-inl.h b/js/src/vm/UnboxedObject-inl.h
new file mode 100644
index 000000000..93ad7bf28
--- /dev/null
+++ b/js/src/vm/UnboxedObject-inl.h
@@ -0,0 +1,840 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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_UnboxedObject_inl_h
+#define vm_UnboxedObject_inl_h
+
+#include "vm/UnboxedObject.h"
+
+#include "gc/StoreBuffer-inl.h"
+#include "vm/ArrayObject-inl.h"
+#include "vm/NativeObject-inl.h"
+
+namespace js {
+
+static inline Value
+GetUnboxedValue(uint8_t* p, JSValueType type, bool maybeUninitialized)
+{
+    switch (type) {
+      case JSVAL_TYPE_BOOLEAN:
+        return BooleanValue(*p != 0);
+
+      case JSVAL_TYPE_INT32:
+        return Int32Value(*reinterpret_cast<int32_t*>(p));
+
+      case JSVAL_TYPE_DOUBLE: {
+        // During unboxed plain object creation, non-GC thing properties are
+        // left uninitialized. This is normally fine, since the properties will
+        // be filled in shortly, but if they are read before that happens we
+        // need to make sure that doubles are canonical.
+        double d = *reinterpret_cast<double*>(p);
+        if (maybeUninitialized)
+            return DoubleValue(JS::CanonicalizeNaN(d));
+        return DoubleValue(d);
+      }
+
+      case JSVAL_TYPE_STRING:
+        return StringValue(*reinterpret_cast<JSString**>(p));
+
+      case JSVAL_TYPE_OBJECT:
+        return ObjectOrNullValue(*reinterpret_cast<JSObject**>(p));
+
+      default:
+        MOZ_CRASH("Invalid type for unboxed value");
+    }
+}
+
+static inline void
+SetUnboxedValueNoTypeChange(JSObject* unboxedObject,
+                            uint8_t* p, JSValueType type, const Value& v,
+                            bool preBarrier)
+{
+    switch (type) {
+      case JSVAL_TYPE_BOOLEAN:
+        *p = v.toBoolean();
+        return;
+
+      case JSVAL_TYPE_INT32:
+        *reinterpret_cast<int32_t*>(p) = v.toInt32();
+        return;
+
+      case JSVAL_TYPE_DOUBLE:
+        *reinterpret_cast<double*>(p) = v.toNumber();
+        return;
+
+      case JSVAL_TYPE_STRING: {
+        MOZ_ASSERT(!IsInsideNursery(v.toString()));
+        JSString** np = reinterpret_cast<JSString**>(p);
+        if (preBarrier)
+            JSString::writeBarrierPre(*np);
+        *np = v.toString();
+        return;
+      }
+
+      case JSVAL_TYPE_OBJECT: {
+        JSObject** np = reinterpret_cast<JSObject**>(p);
+
+        // Manually trigger post barriers on the whole object. If we treat
+        // the pointer as a HeapPtrObject we will get confused later if the
+        // object is converted to its native representation.
+        JSObject* obj = v.toObjectOrNull();
+        if (IsInsideNursery(obj) && !IsInsideNursery(unboxedObject)) {
+            JSRuntime* rt = unboxedObject->runtimeFromMainThread();
+            rt->gc.storeBuffer.putWholeCell(unboxedObject);
+        }
+
+        if (preBarrier)
+            JSObject::writeBarrierPre(*np);
+        *np = obj;
+        return;
+      }
+
+      default:
+        MOZ_CRASH("Invalid type for unboxed value");
+    }
+}
+
+static inline bool
+SetUnboxedValue(ExclusiveContext* cx, JSObject* unboxedObject, jsid id,
+                uint8_t* p, JSValueType type, const Value& v, bool preBarrier)
+{
+    switch (type) {
+      case JSVAL_TYPE_BOOLEAN:
+        if (v.isBoolean()) {
+            *p = v.toBoolean();
+            return true;
+        }
+        return false;
+
+      case JSVAL_TYPE_INT32:
+        if (v.isInt32()) {
+            *reinterpret_cast<int32_t*>(p) = v.toInt32();
+            return true;
+        }
+        return false;
+
+      case JSVAL_TYPE_DOUBLE:
+        if (v.isNumber()) {
+            *reinterpret_cast<double*>(p) = v.toNumber();
+            return true;
+        }
+        return false;
+
+      case JSVAL_TYPE_STRING:
+        if (v.isString()) {
+            MOZ_ASSERT(!IsInsideNursery(v.toString()));
+            JSString** np = reinterpret_cast<JSString**>(p);
+            if (preBarrier)
+                JSString::writeBarrierPre(*np);
+            *np = v.toString();
+            return true;
+        }
+        return false;
+
+      case JSVAL_TYPE_OBJECT:
+        if (v.isObjectOrNull()) {
+            JSObject** np = reinterpret_cast<JSObject**>(p);
+
+            // Update property types when writing object properties. Types for
+            // other properties were captured when the unboxed layout was
+            // created.
+            AddTypePropertyId(cx, unboxedObject, id, v);
+
+            // As above, trigger post barriers on the whole object.
+            JSObject* obj = v.toObjectOrNull();
+            if (IsInsideNursery(v.toObjectOrNull()) && !IsInsideNursery(unboxedObject)) {
+                JSRuntime* rt = unboxedObject->runtimeFromMainThread();
+                rt->gc.storeBuffer.putWholeCell(unboxedObject);
+            }
+
+            if (preBarrier)
+                JSObject::writeBarrierPre(*np);
+            *np = obj;
+            return true;
+        }
+        return false;
+
+      default:
+        MOZ_CRASH("Invalid type for unboxed value");
+    }
+}
+
+/////////////////////////////////////////////////////////////////////
+// UnboxedPlainObject
+/////////////////////////////////////////////////////////////////////
+
+inline const UnboxedLayout&
+UnboxedPlainObject::layout() const
+{
+    return group()->unboxedLayout();
+}
+
+/////////////////////////////////////////////////////////////////////
+// UnboxedArrayObject
+/////////////////////////////////////////////////////////////////////
+
+inline const UnboxedLayout&
+UnboxedArrayObject::layout() const
+{
+    return group()->unboxedLayout();
+}
+
+inline void
+UnboxedArrayObject::setLength(ExclusiveContext* cx, uint32_t length)
+{
+    if (length > INT32_MAX) {
+        // Track objects with overflowing lengths in type information.
+        MarkObjectGroupFlags(cx, this, OBJECT_FLAG_LENGTH_OVERFLOW);
+    }
+
+    length_ = length;
+}
+
+inline void
+UnboxedArrayObject::setInitializedLength(uint32_t initlen)
+{
+    if (initlen < initializedLength()) {
+        switch (elementType()) {
+          case JSVAL_TYPE_STRING:
+            for (size_t i = initlen; i < initializedLength(); i++)
+                triggerPreBarrier<JSVAL_TYPE_STRING>(i);
+            break;
+          case JSVAL_TYPE_OBJECT:
+            for (size_t i = initlen; i < initializedLength(); i++)
+                triggerPreBarrier<JSVAL_TYPE_OBJECT>(i);
+            break;
+          default:
+            MOZ_ASSERT(!UnboxedTypeNeedsPreBarrier(elementType()));
+        }
+    }
+    setInitializedLengthNoBarrier(initlen);
+}
+
+template <JSValueType Type>
+inline bool
+UnboxedArrayObject::setElementSpecific(ExclusiveContext* cx, size_t index, const Value& v)
+{
+    MOZ_ASSERT(index < initializedLength());
+    MOZ_ASSERT(Type == elementType());
+    uint8_t* p = elements() + index * UnboxedTypeSize(Type);
+    return SetUnboxedValue(cx, this, JSID_VOID, p, elementType(), v, /* preBarrier = */ true);
+}
+
+template <JSValueType Type>
+inline void
+UnboxedArrayObject::setElementNoTypeChangeSpecific(size_t index, const Value& v)
+{
+    MOZ_ASSERT(index < initializedLength());
+    MOZ_ASSERT(Type == elementType());
+    uint8_t* p = elements() + index * UnboxedTypeSize(Type);
+    return SetUnboxedValueNoTypeChange(this, p, elementType(), v, /* preBarrier = */ true);
+}
+
+template <JSValueType Type>
+inline bool
+UnboxedArrayObject::initElementSpecific(ExclusiveContext* cx, size_t index, const Value& v)
+{
+    MOZ_ASSERT(index < initializedLength());
+    MOZ_ASSERT(Type == elementType());
+    uint8_t* p = elements() + index * UnboxedTypeSize(Type);
+    return SetUnboxedValue(cx, this, JSID_VOID, p, elementType(), v, /* preBarrier = */ false);
+}
+
+template <JSValueType Type>
+inline void
+UnboxedArrayObject::initElementNoTypeChangeSpecific(size_t index, const Value& v)
+{
+    MOZ_ASSERT(index < initializedLength());
+    MOZ_ASSERT(Type == elementType());
+    uint8_t* p = elements() + index * UnboxedTypeSize(Type);
+    return SetUnboxedValueNoTypeChange(this, p, elementType(), v, /* preBarrier = */ false);
+}
+
+template <JSValueType Type>
+inline Value
+UnboxedArrayObject::getElementSpecific(size_t index)
+{
+    MOZ_ASSERT(index < initializedLength());
+    MOZ_ASSERT(Type == elementType());
+    uint8_t* p = elements() + index * UnboxedTypeSize(Type);
+    return GetUnboxedValue(p, Type, /* maybeUninitialized = */ false);
+}
+
+template <JSValueType Type>
+inline void
+UnboxedArrayObject::triggerPreBarrier(size_t index)
+{
+    MOZ_ASSERT(UnboxedTypeNeedsPreBarrier(Type));
+
+    uint8_t* p = elements() + index * UnboxedTypeSize(Type);
+
+    switch (Type) {
+      case JSVAL_TYPE_STRING: {
+        JSString** np = reinterpret_cast<JSString**>(p);
+        JSString::writeBarrierPre(*np);
+        break;
+      }
+
+      case JSVAL_TYPE_OBJECT: {
+        JSObject** np = reinterpret_cast<JSObject**>(p);
+        JSObject::writeBarrierPre(*np);
+        break;
+      }
+
+      default:
+        MOZ_CRASH("Bad type");
+    }
+}
+
+/////////////////////////////////////////////////////////////////////
+// Combined methods for NativeObject and UnboxedArrayObject accesses.
+/////////////////////////////////////////////////////////////////////
+
+static inline bool
+HasAnyBoxedOrUnboxedDenseElements(JSObject* obj)
+{
+    return obj->isNative() || obj->is<UnboxedArrayObject>();
+}
+
+static inline size_t
+GetAnyBoxedOrUnboxedInitializedLength(JSObject* obj)
+{
+    if (obj->isNative())
+        return obj->as<NativeObject>().getDenseInitializedLength();
+    if (obj->is<UnboxedArrayObject>())
+        return obj->as<UnboxedArrayObject>().initializedLength();
+    return 0;
+}
+
+static inline size_t
+GetAnyBoxedOrUnboxedCapacity(JSObject* obj)
+{
+    if (obj->isNative())
+        return obj->as<NativeObject>().getDenseCapacity();
+    if (obj->is<UnboxedArrayObject>())
+        return obj->as<UnboxedArrayObject>().capacity();
+    return 0;
+}
+
+static inline Value
+GetAnyBoxedOrUnboxedDenseElement(JSObject* obj, size_t index)
+{
+    if (obj->isNative())
+        return obj->as<NativeObject>().getDenseElement(index);
+    return obj->as<UnboxedArrayObject>().getElement(index);
+}
+
+static inline size_t
+GetAnyBoxedOrUnboxedArrayLength(JSObject* obj)
+{
+    if (obj->is<ArrayObject>())
+        return obj->as<ArrayObject>().length();
+    return obj->as<UnboxedArrayObject>().length();
+}
+
+static inline void
+SetAnyBoxedOrUnboxedArrayLength(JSContext* cx, JSObject* obj, size_t length)
+{
+    if (obj->is<ArrayObject>()) {
+        MOZ_ASSERT(length >= obj->as<ArrayObject>().length());
+        obj->as<ArrayObject>().setLength(cx, length);
+    } else {
+        MOZ_ASSERT(length >= obj->as<UnboxedArrayObject>().length());
+        obj->as<UnboxedArrayObject>().setLength(cx, length);
+    }
+}
+
+static inline bool
+SetAnyBoxedOrUnboxedDenseElement(JSContext* cx, JSObject* obj, size_t index, const Value& value)
+{
+    if (obj->isNative()) {
+        obj->as<NativeObject>().setDenseElementWithType(cx, index, value);
+        return true;
+    }
+    return obj->as<UnboxedArrayObject>().setElement(cx, index, value);
+}
+
+static inline bool
+InitAnyBoxedOrUnboxedDenseElement(JSContext* cx, JSObject* obj, size_t index, const Value& value)
+{
+    if (obj->isNative()) {
+        obj->as<NativeObject>().initDenseElementWithType(cx, index, value);
+        return true;
+    }
+    return obj->as<UnboxedArrayObject>().initElement(cx, index, value);
+}
+
+/////////////////////////////////////////////////////////////////////
+// Template methods for NativeObject and UnboxedArrayObject accesses.
+/////////////////////////////////////////////////////////////////////
+
+static inline JSValueType
+GetBoxedOrUnboxedType(JSObject* obj)
+{
+    if (obj->isNative())
+        return JSVAL_TYPE_MAGIC;
+    return obj->as<UnboxedArrayObject>().elementType();
+}
+
+template <JSValueType Type>
+static inline bool
+HasBoxedOrUnboxedDenseElements(JSObject* obj)
+{
+    if (Type == JSVAL_TYPE_MAGIC)
+        return obj->isNative();
+    return obj->is<UnboxedArrayObject>() && obj->as<UnboxedArrayObject>().elementType() == Type;
+}
+
+template <JSValueType Type>
+static inline size_t
+GetBoxedOrUnboxedInitializedLength(JSObject* obj)
+{
+    if (Type == JSVAL_TYPE_MAGIC)
+        return obj->as<NativeObject>().getDenseInitializedLength();
+    return obj->as<UnboxedArrayObject>().initializedLength();
+}
+
+template <JSValueType Type>
+static inline DenseElementResult
+SetBoxedOrUnboxedInitializedLength(JSContext* cx, JSObject* obj, size_t initlen)
+{
+    size_t oldInitlen = GetBoxedOrUnboxedInitializedLength<Type>(obj);
+    if (Type == JSVAL_TYPE_MAGIC) {
+        obj->as<NativeObject>().setDenseInitializedLength(initlen);
+        if (initlen < oldInitlen)
+            obj->as<NativeObject>().shrinkElements(cx, initlen);
+    } else {
+        obj->as<UnboxedArrayObject>().setInitializedLength(initlen);
+        if (initlen < oldInitlen)
+            obj->as<UnboxedArrayObject>().shrinkElements(cx, initlen);
+    }
+    return DenseElementResult::Success;
+}
+
+template <JSValueType Type>
+static inline size_t
+GetBoxedOrUnboxedCapacity(JSObject* obj)
+{
+    if (Type == JSVAL_TYPE_MAGIC)
+        return obj->as<NativeObject>().getDenseCapacity();
+    return obj->as<UnboxedArrayObject>().capacity();
+}
+
+template <JSValueType Type>
+static inline Value
+GetBoxedOrUnboxedDenseElement(JSObject* obj, size_t index)
+{
+    if (Type == JSVAL_TYPE_MAGIC)
+        return obj->as<NativeObject>().getDenseElement(index);
+    return obj->as<UnboxedArrayObject>().getElementSpecific<Type>(index);
+}
+
+template <JSValueType Type>
+static inline void
+SetBoxedOrUnboxedDenseElementNoTypeChange(JSObject* obj, size_t index, const Value& value)
+{
+    if (Type == JSVAL_TYPE_MAGIC)
+        obj->as<NativeObject>().setDenseElement(index, value);
+    else
+        obj->as<UnboxedArrayObject>().setElementNoTypeChangeSpecific<Type>(index, value);
+}
+
+template <JSValueType Type>
+static inline bool
+SetBoxedOrUnboxedDenseElement(JSContext* cx, JSObject* obj, size_t index, const Value& value)
+{
+    if (Type == JSVAL_TYPE_MAGIC) {
+        obj->as<NativeObject>().setDenseElementWithType(cx, index, value);
+        return true;
+    }
+    return obj->as<UnboxedArrayObject>().setElementSpecific<Type>(cx, index, value);
+}
+
+template <JSValueType Type>
+static inline DenseElementResult
+EnsureBoxedOrUnboxedDenseElements(JSContext* cx, JSObject* obj, size_t count)
+{
+    if (Type == JSVAL_TYPE_MAGIC) {
+        if (!obj->as<ArrayObject>().ensureElements(cx, count))
+            return DenseElementResult::Failure;
+    } else {
+        if (obj->as<UnboxedArrayObject>().capacity() < count) {
+            if (!obj->as<UnboxedArrayObject>().growElements(cx, count))
+                return DenseElementResult::Failure;
+        }
+    }
+    return DenseElementResult::Success;
+}
+
+template <JSValueType Type>
+static inline DenseElementResult
+SetOrExtendBoxedOrUnboxedDenseElements(ExclusiveContext* cx, JSObject* obj,
+                                       uint32_t start, const Value* vp, uint32_t count,
+                                       ShouldUpdateTypes updateTypes = ShouldUpdateTypes::Update)
+{
+    if (Type == JSVAL_TYPE_MAGIC) {
+        NativeObject* nobj = &obj->as<NativeObject>();
+
+        if (nobj->denseElementsAreFrozen())
+            return DenseElementResult::Incomplete;
+
+        if (obj->is<ArrayObject>() &&
+            !obj->as<ArrayObject>().lengthIsWritable() &&
+            start + count >= obj->as<ArrayObject>().length())
+        {
+            return DenseElementResult::Incomplete;
+        }
+
+        DenseElementResult result = nobj->ensureDenseElements(cx, start, count);
+        if (result != DenseElementResult::Success)
+            return result;
+
+        if (obj->is<ArrayObject>() && start + count >= obj->as<ArrayObject>().length())
+            obj->as<ArrayObject>().setLengthInt32(start + count);
+
+        if (updateTypes == ShouldUpdateTypes::DontUpdate && !nobj->shouldConvertDoubleElements()) {
+            nobj->copyDenseElements(start, vp, count);
+        } else {
+            for (size_t i = 0; i < count; i++)
+                nobj->setDenseElementWithType(cx, start + i, vp[i]);
+        }
+
+        return DenseElementResult::Success;
+    }
+
+    UnboxedArrayObject* nobj = &obj->as<UnboxedArrayObject>();
+
+    if (start > nobj->initializedLength())
+        return DenseElementResult::Incomplete;
+
+    if (start + count >= UnboxedArrayObject::MaximumCapacity)
+        return DenseElementResult::Incomplete;
+
+    if (start + count > nobj->capacity() && !nobj->growElements(cx, start + count))
+        return DenseElementResult::Failure;
+
+    size_t oldInitlen = nobj->initializedLength();
+
+    // Overwrite any existing elements covered by the new range. If we fail
+    // after this point due to some incompatible type being written to the
+    // object's elements, afterwards the contents will be different from when
+    // we started. The caller must retry the operation using a generic path,
+    // which will overwrite the already-modified elements as well as the ones
+    // that were left alone.
+    size_t i = 0;
+    if (updateTypes == ShouldUpdateTypes::DontUpdate) {
+        for (size_t j = start; i < count && j < oldInitlen; i++, j++)
+            nobj->setElementNoTypeChangeSpecific<Type>(j, vp[i]);
+    } else {
+        for (size_t j = start; i < count && j < oldInitlen; i++, j++) {
+            if (!nobj->setElementSpecific<Type>(cx, j, vp[i]))
+                return DenseElementResult::Incomplete;
+        }
+    }
+
+    if (i != count) {
+        obj->as<UnboxedArrayObject>().setInitializedLength(start + count);
+        if (updateTypes == ShouldUpdateTypes::DontUpdate) {
+            for (; i < count; i++)
+                nobj->initElementNoTypeChangeSpecific<Type>(start + i, vp[i]);
+        } else {
+            for (; i < count; i++) {
+                if (!nobj->initElementSpecific<Type>(cx, start + i, vp[i])) {
+                    nobj->setInitializedLengthNoBarrier(oldInitlen);
+                    return DenseElementResult::Incomplete;
+                }
+            }
+        }
+    }
+
+    if (start + count >= nobj->length())
+        nobj->setLength(cx, start + count);
+
+    return DenseElementResult::Success;
+}
+
+template <JSValueType Type>
+static inline DenseElementResult
+MoveBoxedOrUnboxedDenseElements(JSContext* cx, JSObject* obj, uint32_t dstStart, uint32_t srcStart,
+                                uint32_t length)
+{
+    MOZ_ASSERT(HasBoxedOrUnboxedDenseElements<Type>(obj));
+
+    if (Type == JSVAL_TYPE_MAGIC) {
+        if (obj->as<NativeObject>().denseElementsAreFrozen())
+            return DenseElementResult::Incomplete;
+
+        if (!obj->as<NativeObject>().maybeCopyElementsForWrite(cx))
+            return DenseElementResult::Failure;
+        obj->as<NativeObject>().moveDenseElements(dstStart, srcStart, length);
+    } else {
+        uint8_t* data = obj->as<UnboxedArrayObject>().elements();
+        size_t elementSize = UnboxedTypeSize(Type);
+
+        if (UnboxedTypeNeedsPreBarrier(Type) &&
+            JS::shadow::Zone::asShadowZone(obj->zone())->needsIncrementalBarrier())
+        {
+            // Trigger pre barriers on any elements we are overwriting. See
+            // NativeObject::moveDenseElements. No post barrier is needed as
+            // only whole cell post barriers are used with unboxed objects.
+            for (size_t i = 0; i < length; i++)
+                obj->as<UnboxedArrayObject>().triggerPreBarrier<Type>(dstStart + i);
+        }
+
+        memmove(data + dstStart * elementSize,
+                data + srcStart * elementSize,
+                length * elementSize);
+    }
+
+    return DenseElementResult::Success;
+}
+
+template <JSValueType DstType, JSValueType SrcType>
+static inline DenseElementResult
+CopyBoxedOrUnboxedDenseElements(JSContext* cx, JSObject* dst, JSObject* src,
+                                uint32_t dstStart, uint32_t srcStart, uint32_t length)
+{
+    MOZ_ASSERT(HasBoxedOrUnboxedDenseElements<SrcType>(src));
+    MOZ_ASSERT(HasBoxedOrUnboxedDenseElements<DstType>(dst));
+    MOZ_ASSERT(GetBoxedOrUnboxedInitializedLength<DstType>(dst) == dstStart);
+    MOZ_ASSERT(GetBoxedOrUnboxedInitializedLength<SrcType>(src) >= srcStart + length);
+    MOZ_ASSERT(GetBoxedOrUnboxedCapacity<DstType>(dst) >= dstStart + length);
+
+    SetBoxedOrUnboxedInitializedLength<DstType>(cx, dst, dstStart + length);
+
+    if (DstType == JSVAL_TYPE_MAGIC) {
+        if (SrcType == JSVAL_TYPE_MAGIC) {
+            const Value* vp = src->as<NativeObject>().getDenseElements() + srcStart;
+            dst->as<NativeObject>().initDenseElements(dstStart, vp, length);
+        } else {
+            for (size_t i = 0; i < length; i++) {
+                Value v = GetBoxedOrUnboxedDenseElement<SrcType>(src, srcStart + i);
+                dst->as<NativeObject>().initDenseElement(dstStart + i, v);
+            }
+        }
+    } else if (DstType == SrcType) {
+        uint8_t* dstData = dst->as<UnboxedArrayObject>().elements();
+        uint8_t* srcData = src->as<UnboxedArrayObject>().elements();
+        size_t elementSize = UnboxedTypeSize(DstType);
+
+        memcpy(dstData + dstStart * elementSize,
+               srcData + srcStart * elementSize,
+               length * elementSize);
+
+        // Add a store buffer entry if we might have copied a nursery pointer to dst.
+        if (UnboxedTypeNeedsPostBarrier(DstType) && !IsInsideNursery(dst))
+            dst->runtimeFromMainThread()->gc.storeBuffer.putWholeCell(dst);
+    } else if (DstType == JSVAL_TYPE_DOUBLE && SrcType == JSVAL_TYPE_INT32) {
+        uint8_t* dstData = dst->as<UnboxedArrayObject>().elements();
+        uint8_t* srcData = src->as<UnboxedArrayObject>().elements();
+
+        for (size_t i = 0; i < length; i++) {
+            int32_t v = *reinterpret_cast<int32_t*>(srcData + (srcStart + i) * sizeof(int32_t));
+            *reinterpret_cast<double*>(dstData + (dstStart + i) * sizeof(double)) = v;
+        }
+    } else {
+        for (size_t i = 0; i < length; i++) {
+            Value v = GetBoxedOrUnboxedDenseElement<SrcType>(src, srcStart + i);
+            dst->as<UnboxedArrayObject>().initElementNoTypeChangeSpecific<DstType>(dstStart + i, v);
+        }
+    }
+
+    return DenseElementResult::Success;
+}
+
+/////////////////////////////////////////////////////////////////////
+// Dispatch to specialized methods based on the type of an object.
+/////////////////////////////////////////////////////////////////////
+
+// Goop to fix MSVC. See DispatchTraceKindTyped in TraceKind.h.
+// The clang-cl front end defines _MSC_VER, but still requires the explicit
+// template declaration, so we must test for __clang__ here as well.
+#if defined(_MSC_VER) && !defined(__clang__)
+# define DEPENDENT_TEMPLATE_HINT
+#else
+# define DEPENDENT_TEMPLATE_HINT template
+#endif
+
+// Function to dispatch a method specialized to whatever boxed or unboxed dense
+// elements which an input object has.
+template <typename F>
+DenseElementResult
+CallBoxedOrUnboxedSpecialization(F f, JSObject* obj)
+{
+    if (!HasAnyBoxedOrUnboxedDenseElements(obj))
+        return DenseElementResult::Incomplete;
+    switch (GetBoxedOrUnboxedType(obj)) {
+      case JSVAL_TYPE_MAGIC:
+        return f. DEPENDENT_TEMPLATE_HINT operator()<JSVAL_TYPE_MAGIC>();
+      case JSVAL_TYPE_BOOLEAN:
+        return f. DEPENDENT_TEMPLATE_HINT operator()<JSVAL_TYPE_BOOLEAN>();
+      case JSVAL_TYPE_INT32:
+        return f. DEPENDENT_TEMPLATE_HINT operator()<JSVAL_TYPE_INT32>();
+      case JSVAL_TYPE_DOUBLE:
+        return f. DEPENDENT_TEMPLATE_HINT operator()<JSVAL_TYPE_DOUBLE>();
+      case JSVAL_TYPE_STRING:
+        return f. DEPENDENT_TEMPLATE_HINT operator()<JSVAL_TYPE_STRING>();
+      case JSVAL_TYPE_OBJECT:
+        return f. DEPENDENT_TEMPLATE_HINT operator()<JSVAL_TYPE_OBJECT>();
+      default:
+        MOZ_CRASH();
+    }
+}
+
+// As above, except the specialization can reflect the unboxed type of two objects.
+template <typename F>
+DenseElementResult
+CallBoxedOrUnboxedSpecialization(F f, JSObject* obj1, JSObject* obj2)
+{
+    if (!HasAnyBoxedOrUnboxedDenseElements(obj1) || !HasAnyBoxedOrUnboxedDenseElements(obj2))
+        return DenseElementResult::Incomplete;
+
+#define SPECIALIZE_OBJ2(TYPE)                                                     \
+    switch (GetBoxedOrUnboxedType(obj2)) {                                        \
+      case JSVAL_TYPE_MAGIC:                                                      \
+        return f. DEPENDENT_TEMPLATE_HINT operator()<TYPE, JSVAL_TYPE_MAGIC>();   \
+      case JSVAL_TYPE_BOOLEAN:                                                    \
+        return f. DEPENDENT_TEMPLATE_HINT operator()<TYPE, JSVAL_TYPE_BOOLEAN>(); \
+      case JSVAL_TYPE_INT32:                                                      \
+        return f. DEPENDENT_TEMPLATE_HINT operator()<TYPE, JSVAL_TYPE_INT32>();   \
+      case JSVAL_TYPE_DOUBLE:                                                     \
+        return f. DEPENDENT_TEMPLATE_HINT operator()<TYPE, JSVAL_TYPE_DOUBLE>();  \
+      case JSVAL_TYPE_STRING:                                                     \
+        return f. DEPENDENT_TEMPLATE_HINT operator()<TYPE, JSVAL_TYPE_STRING>();  \
+      case JSVAL_TYPE_OBJECT:                                                     \
+        return f. DEPENDENT_TEMPLATE_HINT operator()<TYPE, JSVAL_TYPE_OBJECT>();  \
+      default:                                                                    \
+        MOZ_CRASH();                                                              \
+    }
+
+    switch (GetBoxedOrUnboxedType(obj1)) {
+      case JSVAL_TYPE_MAGIC:
+        SPECIALIZE_OBJ2(JSVAL_TYPE_MAGIC)
+      case JSVAL_TYPE_BOOLEAN:
+        SPECIALIZE_OBJ2(JSVAL_TYPE_BOOLEAN)
+      case JSVAL_TYPE_INT32:
+        SPECIALIZE_OBJ2(JSVAL_TYPE_INT32)
+      case JSVAL_TYPE_DOUBLE:
+        SPECIALIZE_OBJ2(JSVAL_TYPE_DOUBLE)
+      case JSVAL_TYPE_STRING:
+        SPECIALIZE_OBJ2(JSVAL_TYPE_STRING)
+      case JSVAL_TYPE_OBJECT:
+        SPECIALIZE_OBJ2(JSVAL_TYPE_OBJECT)
+      default:
+        MOZ_CRASH();
+    }
+
+#undef SPECIALIZE_OBJ2
+}
+
+#undef DEPENDENT_TEMPLATE_HINT
+
+#define DefineBoxedOrUnboxedFunctor1(Signature, A)                      \
+struct Signature ## Functor {                                           \
+    A a;                                                                \
+    explicit Signature ## Functor(A a)                                  \
+      : a(a)                                                            \
+    {}                                                                  \
+    template <JSValueType Type>                                         \
+    DenseElementResult operator()() {                                   \
+        return Signature<Type>(a);                                      \
+    }                                                                   \
+}
+
+#define DefineBoxedOrUnboxedFunctor3(Signature, A, B, C)                \
+struct Signature ## Functor {                                           \
+    A a; B b; C c;                                                      \
+    Signature ## Functor(A a, B b, C c)                                 \
+      : a(a), b(b), c(c)                                                \
+    {}                                                                  \
+    template <JSValueType Type>                                         \
+    DenseElementResult operator()() {                                   \
+        return Signature<Type>(a, b, c);                                \
+    }                                                                   \
+}
+
+#define DefineBoxedOrUnboxedFunctor4(Signature, A, B, C, D)             \
+struct Signature ## Functor {                                           \
+    A a; B b; C c; D d;                                                 \
+    Signature ## Functor(A a, B b, C c, D d)                            \
+      : a(a), b(b), c(c), d(d)                                          \
+    {}                                                                  \
+    template <JSValueType Type>                                         \
+    DenseElementResult operator()() {                                   \
+        return Signature<Type>(a, b, c, d);                             \
+    }                                                                   \
+}
+
+#define DefineBoxedOrUnboxedFunctorPair4(Signature, A, B, C, D)         \
+struct Signature ## Functor {                                           \
+    A a; B b; C c; D d;                                                 \
+    Signature ## Functor(A a, B b, C c, D d)                            \
+      : a(a), b(b), c(c), d(d)                                          \
+    {}                                                                  \
+    template <JSValueType TypeOne, JSValueType TypeTwo>                 \
+    DenseElementResult operator()() {                                   \
+        return Signature<TypeOne, TypeTwo>(a, b, c, d);                 \
+    }                                                                   \
+}
+
+#define DefineBoxedOrUnboxedFunctor5(Signature, A, B, C, D, E)          \
+struct Signature ## Functor {                                           \
+    A a; B b; C c; D d; E e;                                            \
+    Signature ## Functor(A a, B b, C c, D d, E e)                       \
+      : a(a), b(b), c(c), d(d), e(e)                                    \
+    {}                                                                  \
+    template <JSValueType Type>                                         \
+    DenseElementResult operator()() {                                   \
+        return Signature<Type>(a, b, c, d, e);                          \
+    }                                                                   \
+}
+
+#define DefineBoxedOrUnboxedFunctor6(Signature, A, B, C, D, E, F)       \
+struct Signature ## Functor {                                           \
+    A a; B b; C c; D d; E e; F f;                                       \
+    Signature ## Functor(A a, B b, C c, D d, E e, F f)                  \
+      : a(a), b(b), c(c), d(d), e(e), f(f)                              \
+    {}                                                                  \
+    template <JSValueType Type>                                         \
+    DenseElementResult operator()() {                                   \
+        return Signature<Type>(a, b, c, d, e, f);                       \
+    }                                                                   \
+}
+
+#define DefineBoxedOrUnboxedFunctorPair6(Signature, A, B, C, D, E, F)   \
+struct Signature ## Functor {                                           \
+    A a; B b; C c; D d; E e; F f;                                       \
+    Signature ## Functor(A a, B b, C c, D d, E e, F f)                  \
+      : a(a), b(b), c(c), d(d), e(e), f(f)                              \
+    {}                                                                  \
+    template <JSValueType TypeOne, JSValueType TypeTwo>                 \
+    DenseElementResult operator()() {                                   \
+        return Signature<TypeOne, TypeTwo>(a, b, c, d, e, f);           \
+    }                                                                   \
+}
+
+DenseElementResult
+SetOrExtendAnyBoxedOrUnboxedDenseElements(ExclusiveContext* cx, JSObject* obj,
+                                          uint32_t start, const Value* vp, uint32_t count,
+                                          ShouldUpdateTypes updateTypes = ShouldUpdateTypes::Update);
+
+DenseElementResult
+MoveAnyBoxedOrUnboxedDenseElements(JSContext* cx, JSObject* obj,
+                                   uint32_t dstStart, uint32_t srcStart, uint32_t length);
+
+DenseElementResult
+CopyAnyBoxedOrUnboxedDenseElements(JSContext* cx, JSObject* dst, JSObject* src,
+                                   uint32_t dstStart, uint32_t srcStart, uint32_t length);
+
+void
+SetAnyBoxedOrUnboxedInitializedLength(JSContext* cx, JSObject* obj, size_t initlen);
+
+DenseElementResult
+EnsureAnyBoxedOrUnboxedDenseElements(JSContext* cx, JSObject* obj, size_t count);
+
+} // namespace js
+
+#endif // vm_UnboxedObject_inl_h