js/src/vm/ArrayObject-inl.h
author Jeff Walden <jwalden@mit.edu>
Sat, 15 Sep 2018 20:24:30 -0700
changeset 492475 60df00079cd46d23309f0637633f62908ba17d45
parent 491462 48c78757dc15531f94c8fd67dd70bc467e74543e
child 492478 3ef024a29617c4e33765d0d9350101798fcee390
permissions -rw-r--r--
Bug 1491736 - Split out type-set classes and related data types from vm/TypeInference.h into vm/TypeSet.h, and move TypeNewScript from vm/TypeInference.h to vm/TypeInference-inl.h, so code can use TypeSet types without needing JSFunction, Shape, and other super-complex types as well (via HeapPtr<T*> fields in TypeNewScript). r=jandem

/* -*- 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_ArrayObject_inl_h
#define vm_ArrayObject_inl_h

#include "vm/ArrayObject.h"

#include "gc/GCTrace.h"
#include "vm/StringType.h"

#include "vm/JSObject-inl.h"
#include "vm/ObjectGroup-inl.h"
#include "vm/TypeInference-inl.h"

namespace js {

inline void
ArrayObject::setLength(JSContext* cx, uint32_t length)
{
    MOZ_ASSERT(lengthIsWritable());
    MOZ_ASSERT_IF(length != getElementsHeader()->length, !denseElementsAreFrozen());

    if (length > INT32_MAX) {
        /* Track objects with overflowing lengths in type information. */
        MarkObjectGroupFlags(cx, this, OBJECT_FLAG_LENGTH_OVERFLOW);
    }

    getElementsHeader()->length = length;
}

/* static */ inline ArrayObject*
ArrayObject::createArrayInternal(JSContext* cx, gc::AllocKind kind, gc::InitialHeap heap,
                                 HandleShape shape, HandleObjectGroup group,
                                 AutoSetNewObjectMetadata&)
{
    const js::Class* clasp = group->clasp();
    MOZ_ASSERT(shape && group);
    MOZ_ASSERT(clasp == shape->getObjectClass());
    MOZ_ASSERT(clasp == &ArrayObject::class_);
    MOZ_ASSERT_IF(clasp->hasFinalize(), heap == gc::TenuredHeap);
    MOZ_ASSERT_IF(group->hasUnanalyzedPreliminaryObjects(),
                  heap == js::gc::TenuredHeap);

    // Arrays can use their fixed slots to store elements, so can't have shapes
    // which allow named properties to be stored in the fixed slots.
    MOZ_ASSERT(shape->numFixedSlots() == 0);

    size_t nDynamicSlots = dynamicSlotsCount(0, shape->slotSpan(), clasp);
    JSObject* obj = js::Allocate<JSObject>(cx, kind, nDynamicSlots, heap, clasp);
    if (!obj) {
        return nullptr;
    }

    ArrayObject* aobj = static_cast<ArrayObject*>(obj);
    aobj->initGroup(group);
    aobj->initShape(shape);
    // NOTE: Dynamic slots are created internally by Allocate<JSObject>.
    if (!nDynamicSlots) {
        aobj->initSlots(nullptr);
    }

    MOZ_ASSERT(clasp->shouldDelayMetadataBuilder());
    cx->realm()->setObjectPendingMetadata(cx, aobj);

    return aobj;
}

/* static */ inline ArrayObject*
ArrayObject::finishCreateArray(ArrayObject* obj, HandleShape shape, AutoSetNewObjectMetadata& metadata)
{
    size_t span = shape->slotSpan();
    if (span) {
        obj->initializeSlotRange(0, span);
    }

    gc::gcTracer.traceCreateObject(obj);

    return obj;
}

/* static */ inline ArrayObject*
ArrayObject::createArray(JSContext* cx, gc::AllocKind kind, gc::InitialHeap heap,
                         HandleShape shape, HandleObjectGroup group,
                         uint32_t length, AutoSetNewObjectMetadata& metadata)
{
    ArrayObject* obj = createArrayInternal(cx, kind, heap, shape, group, metadata);
    if (!obj) {
        return nullptr;
    }

    uint32_t capacity = gc::GetGCKindSlots(kind) - ObjectElements::VALUES_PER_HEADER;

    obj->setFixedElements();
    new (obj->getElementsHeader()) ObjectElements(capacity, length);

    return finishCreateArray(obj, shape, metadata);
}

/* static */ inline ArrayObject*
ArrayObject::createCopyOnWriteArray(JSContext* cx, gc::InitialHeap heap,
                                    HandleArrayObject sharedElementsOwner)
{
    MOZ_ASSERT(sharedElementsOwner->getElementsHeader()->isCopyOnWrite());
    MOZ_ASSERT(sharedElementsOwner->getElementsHeader()->ownerObject() == sharedElementsOwner);

    // Use the smallest allocation kind for the array, as it can't have any
    // fixed slots (see the assert in createArrayInternal) and will not be using
    // its fixed elements.
    gc::AllocKind kind = gc::AllocKind::OBJECT0_BACKGROUND;

    AutoSetNewObjectMetadata metadata(cx);
    RootedShape shape(cx, sharedElementsOwner->lastProperty());
    RootedObjectGroup group(cx, sharedElementsOwner->group());
    ArrayObject* obj = createArrayInternal(cx, kind, heap, shape, group, metadata);
    if (!obj) {
        return nullptr;
    }

    obj->elements_ = sharedElementsOwner->getDenseElementsAllowCopyOnWrite();

    return finishCreateArray(obj, shape, metadata);
}

} // namespace js

#endif // vm_ArrayObject_inl_h