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138 lines
3.9 KiB
C++
138 lines
3.9 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* vim: set ts=8 sts=4 et sw=4 tw=99:
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef vm_ReceiverGuard_h
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#define vm_ReceiverGuard_h
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#include "vm/Shape.h"
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namespace js {
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// A ReceiverGuard encapsulates the information about an object that needs to
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// be tested to determine if it has the same 'structure' as another object.
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// The guard includes the shape and/or group of the object, and which of these
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// is tested, as well as the meaning here of 'structure', depends on the kind
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// of object being tested:
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//
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// NativeObject: The structure of a native object is determined by its shape.
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// Two objects with the same shape have the same class, prototype, flags,
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// and all properties except those stored in dense elements.
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//
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// ProxyObject: The structure of a proxy object is determined by its shape.
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// Proxies with the same shape have the same class and prototype, but no
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// other commonality is guaranteed.
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//
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// TypedObject: The structure of a typed object is determined by its group.
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// All typed objects with the same group have the same class, prototype, and
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// own properties.
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//
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// UnboxedPlainObject: The structure of an unboxed plain object is determined
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// by its group and its expando object's shape, if there is one. All unboxed
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// plain objects with the same group and expando shape have the same
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// properties except those stored in the expando's dense elements.
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class HeapReceiverGuard;
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class RootedReceiverGuard;
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class ReceiverGuard
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{
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public:
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ObjectGroup* group;
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Shape* shape;
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ReceiverGuard()
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: group(nullptr), shape(nullptr)
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{}
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inline MOZ_IMPLICIT ReceiverGuard(const HeapReceiverGuard& guard);
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inline MOZ_IMPLICIT ReceiverGuard(const RootedReceiverGuard& guard);
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explicit ReceiverGuard(JSObject* obj);
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ReceiverGuard(ObjectGroup* group, Shape* shape);
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bool operator ==(const ReceiverGuard& other) const {
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return group == other.group && shape == other.shape;
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}
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bool operator !=(const ReceiverGuard& other) const {
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return !(*this == other);
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}
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uintptr_t hash() const {
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return (uintptr_t(group) >> 3) ^ (uintptr_t(shape) >> 3);
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}
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};
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class HeapReceiverGuard
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{
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HeapPtrObjectGroup group_;
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HeapPtrShape shape_;
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public:
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explicit HeapReceiverGuard(const ReceiverGuard& guard)
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: group_(guard.group), shape_(guard.shape)
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{}
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bool matches(const ReceiverGuard& guard) {
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return group_ == guard.group && shape_ == guard.shape;
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}
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void update(const ReceiverGuard& other) {
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group_ = other.group;
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shape_ = other.shape;
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}
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void init(const ReceiverGuard& other) {
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group_.init(other.group);
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shape_.init(other.shape);
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}
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void trace(JSTracer* trc);
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Shape* shape() const {
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return shape_;
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}
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ObjectGroup* group() const {
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return group_;
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}
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static size_t offsetOfShape() {
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return offsetof(HeapReceiverGuard, shape_);
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}
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static size_t offsetOfGroup() {
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return offsetof(HeapReceiverGuard, group_);
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}
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// Bits to munge into Baseline IC compiler keys when that IC has a
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// HeapReceiverGuard. This uses at most two bits for data.
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static int32_t keyBits(JSObject* obj);
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};
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class RootedReceiverGuard
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{
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public:
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RootedObjectGroup group;
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RootedShape shape;
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RootedReceiverGuard(JSContext* cx, const ReceiverGuard& guard)
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: group(cx, guard.group), shape(cx, guard.shape)
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{}
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};
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inline
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ReceiverGuard::ReceiverGuard(const HeapReceiverGuard& guard)
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: group(guard.group()), shape(guard.shape())
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{}
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inline
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ReceiverGuard::ReceiverGuard(const RootedReceiverGuard& guard)
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: group(guard.group), shape(guard.shape)
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{}
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} // namespace js
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#endif /* vm_ReceiverGuard_h */
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