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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 et tw=78:
*
* 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 jsgc_root_h__
#define jsgc_root_h__
#include "mozilla/GuardObjects.h"
#include "mozilla/TypeTraits.h"
#include "js/Utility.h"
#include "js/TemplateLib.h"
#include "jspubtd.h"
/*
* Moving GC Stack Rooting
*
* A moving GC may change the physical location of GC allocated things, even
* when they are rooted, updating all pointers to the thing to refer to its new
* location. The GC must therefore know about all live pointers to a thing,
* not just one of them, in order to behave correctly.
*
* The |Root| and |Handle| classes below are used to root stack locations
* whose value may be held live across a call that can trigger GC. For a
* code fragment such as:
*
* JSObject *obj = NewObject(cx);
* DoSomething(cx);
* ... = obj->lastProperty();
*
* If |DoSomething()| can trigger a GC, the stack location of |obj| must be
* rooted to ensure that the GC does not move the JSObject referred to by
* |obj| without updating |obj|'s location itself. This rooting must happen
* regardless of whether there are other roots which ensure that the object
* itself will not be collected.
*
* If |DoSomething()| cannot trigger a GC, and the same holds for all other
* calls made between |obj|'s definitions and its last uses, then no rooting
* is required. The |Unrooted| class below is used to ensure that this
* property is true and remains true in the future.
*
* SpiderMonkey can trigger a GC at almost any time and in ways that are not
* always clear. For example, the following innocuous-looking actions can
* cause a GC: allocation of any new GC thing; JSObject::hasProperty;
* JS_ReportError and friends; and ToNumber, among many others. The following
* dangerous-looking actions cannot trigger a GC: js_malloc, cx->malloc_,
* rt->malloc_, and friends and JS_ReportOutOfMemory.
*
* The following family of four classes will exactly root a stack location.
* Incorrect usage of these classes will result in a compile error in almost
* all cases. Therefore, it is very hard to be incorrectly rooted if you use
* these classes exclusively. These classes are all templated on the type T of
* the value being rooted.
*
* - Rooted<T> declares a variable of type T, whose value is always rooted.
* Rooted<T> may be automatically coerced to a Handle<T>, below. Rooted<T>
* should be used whenever a local variable's value may be held live across a
* call which can trigger a GC. This is generally true of
*
* - Handle<T> is a const reference to a Rooted<T>. Functions which take GC
* things or values as arguments and need to root those arguments should
* generally use handles for those arguments and avoid any explicit rooting.
* This has two benefits. First, when several such functions call each other
* then redundant rooting of multiple copies of the GC thing can be avoided.
* Second, if the caller does not pass a rooted value a compile error will be
* generated, which is quicker and easier to fix than when relying on a
* separate rooting analysis.
*
* - MutableHandle<T> is a non-const reference to Rooted<T>. It is used in the
* same way as Handle<T> and includes a |set(const T &v)| method to allow
* updating the value of the referenced Rooted<T>. A MutableHandle<T> can be
* created from a Rooted<T> by using |Rooted<T>::operator&()|.
*
* In some cases the small performance overhead of exact rooting is too much.
* In these cases, try the following:
*
* - Move all Rooted<T> above inner loops: this allows you to re-use the root
* on each iteration of the loop.
*
* - Pass Handle<T> through your hot call stack to avoid re-rooting costs at
* every invocation.
*
* If this is not enough, the following family of two classes and two
* functions can provide partially type-safe and mostly runtime-safe access to
* GC things.
*
* - AutoAssertNoGC is a scoped guard that will trigger an assertion if a GC,
* or an appropriately marked method that might GC, is entered when it is in
* scope. By convention the name given to instances of this guard is |nogc|.
*
* - AssertCanGC() will assert if an AutoAssertNoGC is in scope either locally
* or anywhere in the call stack.
*
* - UnrootedT is a typedef for a pointer to thing of type T. In DEBUG builds
* it gets replaced by a class that additionally acts as an AutoAssertNoGC
* guard. Since there is only minimal compile-time protection against
* mis-use, UnrootedT should only be used in places where there is adequate
* coverage of AutoAssertNoGC and AssertCanGC guards to ensure that mis-use
* is caught at runtime.
*
* - DropUnrooted(UnrootedT &v) will poison |v| and end its AutoAssertNoGC
* scope. This can be used to force |v| out of scope before its C++ scope
* would end naturally. The usage of braces C++ syntactical scopes |{...}|
* is strongly perferred to this, but sometimes will not work because of
* awkwardly overlapping lifetimes.
*
* There also exists a set of RawT typedefs for modules without rooting
* concerns, such as the GC. Do not use these as they provide no rooting
* protection whatsoever.
*
* The following diagram explains the list of supported, implicit type
* conversions between classes of this family:
*
* RawT ----> UnrootedT
* | ^
* | |
* | v
* +--------> Rooted<T> <---> Handle<T>
* ^ ^
* | |
* | |
* +---> MutableHandle<T>
* (via &)
*
* Currently all of these types implicit conversion to RawT. These are present
* only for the purpose of bootstrapping exact rooting and will be removed in
* the future (Bug 817164).
*/
namespace js {
template <typename T> class Rooted;
template <typename T> class Unrooted;
template <typename T>
struct RootMethods {};
template <typename T>
class RootedBase {};
template <typename T>
class HandleBase {};
template <typename T>
class MutableHandleBase {};
} /* namespace js */
namespace JS {
class AutoAssertNoGC;
template <typename T> class Handle;
template <typename T> class MutableHandle;
JS_FRIEND_API(void) EnterAssertNoGCScope();
JS_FRIEND_API(void) LeaveAssertNoGCScope();
/* These are exposing internal state of the GC for inlining purposes. */
JS_FRIEND_API(bool) InNoGCScope();
JS_FRIEND_API(bool) isGCEnabled();
/*
* Handle provides an implicit constructor for NullPtr so that, given:
* foo(Handle<JSObject*> h);
* callers can simply write:
* foo(NullPtr());
* which avoids creating a Rooted<JSObject*> just to pass NULL.
*/
struct NullPtr
{
static void * const constNullValue;
};
/*
* Reference to a T that has been rooted elsewhere. This is most useful
* as a parameter type, which guarantees that the T lvalue is properly
* rooted. See "Move GC Stack Rooting" above.
*
* If you want to add additional methods to Handle for a specific
* specialization, define a HandleBase<T> specialization containing them.
*/
template <typename T>
class Handle : public js::HandleBase<T>
{
friend class MutableHandle<T>;
public:
/* Creates a handle from a handle of a type convertible to T. */
template <typename S>
Handle(Handle<S> handle,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy = 0)
{
ptr = reinterpret_cast<const T *>(handle.address());
}
/* Create a handle for a NULL pointer. */
Handle(NullPtr) {
typedef typename js::tl::StaticAssert<js::tl::IsPointerType<T>::result>::result _;
ptr = reinterpret_cast<const T *>(&NullPtr::constNullValue);
}
Handle(MutableHandle<T> handle) {
ptr = handle.address();
}
/*
* This may be called only if the location of the T is guaranteed
* to be marked (for some reason other than being a Rooted),
* e.g., if it is guaranteed to be reachable from an implicit root.
*
* Create a Handle from a raw location of a T.
*/
static Handle fromMarkedLocation(const T *p) {
Handle h;
h.ptr = p;
return h;
}
/*
* Construct a handle from an explicitly rooted location. This is the
* normal way to create a handle, and normally happens implicitly.
*/
template <typename S>
inline
Handle(js::Rooted<S> &root,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy = 0);
/* Construct a read only handle from a mutable handle. */
template <typename S>
inline
Handle(MutableHandle<S> &root,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy = 0);
const T *address() const { return ptr; }
T get() const { return *ptr; }
operator T() const { return get(); }
T operator->() const { return get(); }
bool operator!=(const T &other) { return *ptr != other; }
private:
Handle() {}
const T *ptr;
template <typename S>
void operator=(S v) MOZ_DELETE;
};
typedef Handle<JSObject*> HandleObject;
typedef Handle<JSFunction*> HandleFunction;
typedef Handle<JSScript*> HandleScript;
typedef Handle<JSString*> HandleString;
typedef Handle<jsid> HandleId;
typedef Handle<Value> HandleValue;
/*
* Similar to a handle, but the underlying storage can be changed. This is
* useful for outparams.
*
* If you want to add additional methods to MutableHandle for a specific
* specialization, define a MutableHandleBase<T> specialization containing
* them.
*/
template <typename T>
class MutableHandle : public js::MutableHandleBase<T>
{
public:
template <typename S>
MutableHandle(MutableHandle<S> handle,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy = 0)
{
this->ptr = reinterpret_cast<const T *>(handle.address());
}
template <typename S>
inline MutableHandle(js::Rooted<S> *root,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy = 0);
void set(T v) {
JS_ASSERT(!js::RootMethods<T>::poisoned(v));
*ptr = v;
}
template <typename S>
inline void set(const js::Unrooted<S> &v);
/*
* This may be called only if the location of the T is guaranteed
* to be marked (for some reason other than being a Rooted),
* e.g., if it is guaranteed to be reachable from an implicit root.
*
* Create a MutableHandle from a raw location of a T.
*/
static MutableHandle fromMarkedLocation(T *p) {
MutableHandle h;
h.ptr = p;
return h;
}
T *address() const { return ptr; }
T get() const { return *ptr; }
operator T() const { return get(); }
T operator->() const { return get(); }
private:
MutableHandle() {}
T *ptr;
template <typename S>
void operator=(S v) MOZ_DELETE;
};
typedef MutableHandle<JSObject*> MutableHandleObject;
typedef MutableHandle<JSFunction*> MutableHandleFunction;
typedef MutableHandle<JSScript*> MutableHandleScript;
typedef MutableHandle<JSString*> MutableHandleString;
typedef MutableHandle<jsid> MutableHandleId;
typedef MutableHandle<Value> MutableHandleValue;
} /* namespace JS */
namespace js {
/*
* Raw pointer used as documentation that a parameter does not need to be
* rooted.
*/
typedef JSObject * RawObject;
typedef JSString * RawString;
typedef jsid RawId;
typedef JS::Value RawValue;
/*
* InternalHandle is a handle to an internal pointer into a gcthing. Use
* InternalHandle when you have a pointer to a direct field of a gcthing, or
* when you need a parameter type for something that *may* be a pointer to a
* direct field of a gcthing.
*/
template <typename T>
class InternalHandle {};
template <typename T>
class InternalHandle<T*>
{
void * const *holder;
size_t offset;
public:
/*
* Create an InternalHandle using a Handle to the gcthing containing the
* field in question, and a pointer to the field.
*/
template<typename H>
InternalHandle(const JS::Handle<H> &handle, T *field)
: holder((void**)handle.address()), offset(uintptr_t(field) - uintptr_t(handle.get()))
{}
/*
* Create an InternalHandle to a field within a Rooted<>.
*/
template<typename R>
InternalHandle(const Rooted<R> &root, T *field)
: holder((void**)root.address()), offset(uintptr_t(field) - uintptr_t(root.get()))
{}
T *get() const { return reinterpret_cast<T*>(uintptr_t(*holder) + offset); }
const T &operator*() const { return *get(); }
T *operator->() const { return get(); }
static InternalHandle<T*> fromMarkedLocation(T *fieldPtr) {
return InternalHandle(fieldPtr);
}
private:
/*
* Create an InternalHandle to something that is not a pointer to a
* gcthing, and so does not need to be rooted in the first place. Use these
* InternalHandles to pass pointers into functions that also need to accept
* regular InternalHandles to gcthing fields.
*
* Make this private to prevent accidental misuse; this is only for
* fromMarkedLocation().
*/
InternalHandle(T *field)
: holder(reinterpret_cast<void * const *>(&JS::NullPtr::constNullValue)),
offset(uintptr_t(field))
{}
};
#ifdef DEBUG
/*
* |Unrooted<T>| acts as an AutoAssertNoGC after it is initialized. It otherwise
* acts like as a normal pointer of type T.
*/
template <typename T>
class Unrooted
{
public:
Unrooted() : ptr_(UninitializedTag()) {}
/*
* |Unrooted<T>| can be initialized from a convertible |Rooted<S>| or
* |Handle<S>|. This is so that we can call AutoAssertNoGC methods that
* take |Unrooted<T>| parameters with a convertible rooted argument
* without explicit unpacking.
*
* Note: Even though this allows implicit conversion to |Unrooted<T>|
* type, this is safe because Unrooted<T> acts as an AutoAssertNoGC scope.
*/
template <typename S>
inline Unrooted(const Rooted<S> &root,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy = 0);
template <typename S>
Unrooted(const JS::Handle<S> &root,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy = 0)
: ptr_(root.get())
{
JS_ASSERT(ptr_ != UninitializedTag());
JS::EnterAssertNoGCScope();
}
/*
* |Unrooted<T>| can initialize by copying from a convertible type
* |Unrooted<S>|. This enables usage such as:
*
* Unrooted<BaseShape*> base = js_NewBaseShape(cx);
* Unrooted<UnownedBaseShape*> ubase = static_cast<UnrootedUnownedBaseShape>(ubase);
*/
template <typename S>
Unrooted(const Unrooted<S> &other)
/* Note: |static_cast<S>| acquires other.ptr_ in DEBUG builds. */
: ptr_(static_cast<T>(static_cast<S>(other)))
{
if (ptr_ != UninitializedTag())
JS::EnterAssertNoGCScope();
}
Unrooted(const Unrooted &other) : ptr_(other.ptr_) {
if (ptr_ != UninitializedTag())
JS::EnterAssertNoGCScope();
}
Unrooted(const T &p) : ptr_(p) {
JS_ASSERT(ptr_ != UninitializedTag());
JS::EnterAssertNoGCScope();
}
Unrooted(const JS::NullPtr &) : ptr_(NULL) {
JS::EnterAssertNoGCScope();
}
~Unrooted() {
if (ptr_ != UninitializedTag())
JS::LeaveAssertNoGCScope();
}
void drop() {
if (ptr_ != UninitializedTag())
JS::LeaveAssertNoGCScope();
ptr_ = UninitializedTag();
}
/* See notes for Unrooted::Unrooted(const T &) */
Unrooted &operator=(T other) {
JS_ASSERT(other != UninitializedTag());
if (ptr_ == UninitializedTag())
JS::EnterAssertNoGCScope();
ptr_ = other;
return *this;
}
Unrooted &operator=(Unrooted other) {
JS_ASSERT(other.ptr_ != UninitializedTag());
if (ptr_ == UninitializedTag())
JS::EnterAssertNoGCScope();
ptr_ = other.ptr_;
return *this;
}
operator T() const { return (ptr_ == UninitializedTag()) ? NULL : ptr_; }
T *operator&() { return &ptr_; }
const T operator->() const { JS_ASSERT(ptr_ != UninitializedTag()); return ptr_; }
bool operator==(const T &other) { return ptr_ == other; }
bool operator!=(const T &other) { return ptr_ != other; }
private:
/*
* The after-initialization constraint is to handle the case:
*
* Unrooted<Foo> foo = js_NewFoo(cx);
*
* In this case, C++ may run the default constructor, then call MaybeGC,
* and finally call the assignment operator. We cannot handle this case by
* simply checking if the pointer is NULL, since that would disable the
* NoGCScope on assignment. Instead we tag the pointer when we should
* disable the LeaveNoGCScope.
*/
static inline T UninitializedTag() { return reinterpret_cast<T>(1); };
T ptr_;
};
/*
* This macro simplifies declaration of the required matching raw-pointer for
* optimized builds and Unrooted<T> template for debug builds.
*/
# define ForwardDeclare(type) \
class type; \
typedef Unrooted<type*> Unrooted##type; \
typedef type * Raw##type
# define ForwardDeclareJS(type) \
class JS##type; \
namespace js { \
typedef js::Unrooted<JS##type*> Unrooted##type; \
typedef JS##type * Raw##type; \
} \
class JS##type
template <typename T>
T DropUnrooted(Unrooted<T> &unrooted)
{
T rv = unrooted;
unrooted.drop();
return rv;
}
template <typename T>
T DropUnrooted(T &unrooted)
{
T rv = unrooted;
JS::PoisonPtr(&unrooted);
return rv;
}
template <>
inline RawId DropUnrooted(RawId &id) { return id; }
#else /* NDEBUG */
/* In opt builds |UnrootedFoo| is a real |Foo*|. */
# define ForwardDeclare(type) \
class type; \
typedef type * Unrooted##type; \
typedef type * Raw##type
# define ForwardDeclareJS(type) \
class JS##type; \
namespace js { \
typedef JS##type * Unrooted##type; \
typedef JS##type * Raw##type; \
} \
class JS##type
template <typename T>
class Unrooted
{
private:
Unrooted() MOZ_DELETE;
Unrooted(const Unrooted &) MOZ_DELETE;
~Unrooted() MOZ_DELETE;
};
template <typename T>
T DropUnrooted(T &unrooted) { return unrooted; }
#endif /* DEBUG */
/*
* By default, pointers should use the inheritance hierarchy to find their
* ThingRootKind. Some pointer types are explicitly set in jspubtd.h so that
* Rooted<T> may be used without the class definition being available.
*/
template <typename T>
struct RootKind<T *>
{
static ThingRootKind rootKind() { return T::rootKind(); }
};
template <typename T>
struct RootMethods<T *>
{
static T *initial() { return NULL; }
static ThingRootKind kind() { return RootKind<T *>::rootKind(); }
static bool poisoned(T *v) { return IsPoisonedPtr(v); }
};
/*
* Local variable of type T whose value is always rooted. This is typically
* used for local variables, or for non-rooted values being passed to a
* function that requires a handle, e.g. Foo(Root<T>(cx, x)).
*
* If you want to add additional methods to Rooted for a specific
* specialization, define a RootedBase<T> specialization containing them.
*/
template <typename T>
class Rooted : public RootedBase<T>
{
void init(JSContext *cxArg) {
#if defined(JSGC_ROOT_ANALYSIS) || defined(JSGC_USE_EXACT_ROOTING)
ContextFriendFields *cx = ContextFriendFields::get(cxArg);
commonInit(cx->thingGCRooters);
#endif
}
void init(JSRuntime *rtArg) {
#if defined(JSGC_ROOT_ANALYSIS) || defined(JSGC_USE_EXACT_ROOTING)
PerThreadDataFriendFields *pt = PerThreadDataFriendFields::getMainThread(rtArg);
commonInit(pt->thingGCRooters);
#endif
}
void init(js::PerThreadData *ptArg) {
#if defined(JSGC_ROOT_ANALYSIS) || defined(JSGC_USE_EXACT_ROOTING)
PerThreadDataFriendFields *pt = PerThreadDataFriendFields::get(ptArg);
commonInit(pt->thingGCRooters);
#endif
}
public:
Rooted(JSRuntime *rt
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(RootMethods<T>::initial())
#if defined(JSGC_ROOT_ANALYSIS)
, scanned(false)
#endif
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(rt);
}
Rooted(JSRuntime *rt, T initial
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(initial)
#if defined(JSGC_ROOT_ANALYSIS)
, scanned(false)
#endif
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(rt);
}
Rooted(JSContext *cx
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(RootMethods<T>::initial())
#if defined(JSGC_ROOT_ANALYSIS)
, scanned(false)
#endif
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(cx);
}
Rooted(JSContext *cx, T initial
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(initial)
#if defined(JSGC_ROOT_ANALYSIS)
, scanned(false)
#endif
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(cx);
}
Rooted(js::PerThreadData *pt
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(RootMethods<T>::initial())
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(pt);
}
Rooted(js::PerThreadData *pt, T initial
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(initial)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(pt);
}
template <typename S>
Rooted(JSContext *cx, const Unrooted<S> &initial
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(static_cast<S>(initial))
#if defined(JSGC_ROOT_ANALYSIS)
, scanned(false)
#endif
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(cx);
}
~Rooted() {
#if defined(JSGC_ROOT_ANALYSIS) || defined(JSGC_USE_EXACT_ROOTING)
JS_ASSERT(*stack == this);
*stack = prev;
#endif
}
#if defined(JSGC_ROOT_ANALYSIS) || defined(JSGC_USE_EXACT_ROOTING)
Rooted<T> *previous() { return prev; }
#endif
operator T() const { return ptr; }
T operator->() const { return ptr; }
T *address() { return &ptr; }
const T *address() const { return &ptr; }
T &get() { return ptr; }
const T &get() const { return ptr; }
T &operator=(T value) {
JS_ASSERT(!RootMethods<T>::poisoned(value));
ptr = value;
return ptr;
}
T &operator=(const Rooted &value) {
ptr = value;
return ptr;
}
private:
void commonInit(Rooted<void*> **thingGCRooters) {
#if defined(JSGC_ROOT_ANALYSIS) || defined(JSGC_USE_EXACT_ROOTING)
ThingRootKind kind = RootMethods<T>::kind();
this->stack = reinterpret_cast<Rooted<T>**>(&thingGCRooters[kind]);
this->prev = *stack;
*stack = this;
JS_ASSERT(!RootMethods<T>::poisoned(ptr));
#endif
}
#if defined(JSGC_ROOT_ANALYSIS) || defined(JSGC_USE_EXACT_ROOTING)
Rooted<T> **stack, *prev;
#endif
T ptr;
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
Rooted(const Rooted &) MOZ_DELETE;
#if defined(JSGC_ROOT_ANALYSIS)
public:
/* Has the rooting analysis ever scanned this Rooted's stack location? */
bool scanned;
#endif
};
#if !(defined(JSGC_ROOT_ANALYSIS) || defined(JSGC_USE_EXACT_ROOTING))
// Defined in vm/String.h.
template <>
class Rooted<JSStableString *>;
#endif
#ifdef DEBUG
template <typename T> template <typename S>
inline
Unrooted<T>::Unrooted(const Rooted<S> &root,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy)
: ptr_(root.get())
{
JS_ASSERT(ptr_ != UninitializedTag());
JS::EnterAssertNoGCScope();
}
#endif /* DEBUG */
typedef Rooted<JSObject*> RootedObject;
typedef Rooted<JSFunction*> RootedFunction;
typedef Rooted<JSScript*> RootedScript;
typedef Rooted<JSString*> RootedString;
typedef Rooted<jsid> RootedId;
typedef Rooted<JS::Value> RootedValue;
/*
* Mark a stack location as a root for the rooting analysis, without actually
* rooting it in release builds. This should only be used for stack locations
* of GC things that cannot be relocated by a garbage collection, and that
* are definitely reachable via another path.
*/
class SkipRoot
{
#if defined(DEBUG) && defined(JS_GC_ZEAL) && defined(JSGC_ROOT_ANALYSIS) && !defined(JS_THREADSAFE)
SkipRoot **stack, *prev;
const uint8_t *start;
const uint8_t *end;
template <typename T>
void init(ContextFriendFields *cx, const T *ptr, size_t count) {
this->stack = &cx->skipGCRooters;
this->prev = *stack;
*stack = this;
this->start = (const uint8_t *) ptr;
this->end = this->start + (sizeof(T) * count);
}
public:
template <typename T>
SkipRoot(JSContext *cx, const T *ptr, size_t count = 1
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
{
init(ContextFriendFields::get(cx), ptr, count);
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
}
~SkipRoot() {
JS_ASSERT(*stack == this);
*stack = prev;
}
SkipRoot *previous() { return prev; }
bool contains(const uint8_t *v, size_t len) {
return v >= start && v + len <= end;
}
#else /* DEBUG && JSGC_ROOT_ANALYSIS */
public:
template <typename T>
SkipRoot(JSContext *cx, const T *ptr, size_t count = 1
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
}
#endif /* DEBUG && JSGC_ROOT_ANALYSIS */
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
};
} /* namespace js */
namespace JS {
template <typename T> template <typename S>
inline
Handle<T>::Handle(js::Rooted<S> &root,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy)
{
ptr = reinterpret_cast<const T *>(root.address());
}
template <typename T> template <typename S>
inline
Handle<T>::Handle(MutableHandle<S> &root,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy)
{
ptr = reinterpret_cast<const T *>(root.address());
}
template <typename T> template <typename S>
inline
MutableHandle<T>::MutableHandle(js::Rooted<S> *root,
typename mozilla::EnableIf<mozilla::IsConvertible<S, T>::value, int>::Type dummy)
{
ptr = root->address();
}
template <typename T> template <typename S>
inline void MutableHandle<T>::set(const js::Unrooted<S> &v)
{
JS_ASSERT(!js::RootMethods<T>::poisoned(v));
*ptr = static_cast<S>(v);
}
/*
* The scoped guard object AutoAssertNoGC forces the GC to assert if a GC is
* attempted while the guard object is live. If you have a GC-unsafe operation
* to perform, use this guard object to protect your operation.
*/
class AutoAssertNoGC
{
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
public:
AutoAssertNoGC(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM) {
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
#ifdef DEBUG
EnterAssertNoGCScope();
#endif
}
~AutoAssertNoGC() {
#ifdef DEBUG
LeaveAssertNoGCScope();
#endif
}
};
/*
* AssertCanGC will assert if it is called inside of an AutoAssertNoGC region.
*/
JS_ALWAYS_INLINE void
AssertCanGC()
{
JS_ASSERT_IF(isGCEnabled(), !InNoGCScope());
}
#if defined(DEBUG) && defined(JS_GC_ZEAL) && defined(JSGC_ROOT_ANALYSIS) && !defined(JS_THREADSAFE)
extern void
CheckStackRoots(JSContext *cx);
#endif
JS_FRIEND_API(bool) NeedRelaxedRootChecks();
} /* namespace JS */
namespace js {
/*
* Hook for dynamic root analysis. Checks the native stack and poisons
* references to GC things which have not been rooted.
*/
inline void MaybeCheckStackRoots(JSContext *cx, bool relax = true)
{
JS::AssertCanGC();
#if defined(DEBUG) && defined(JS_GC_ZEAL) && defined(JSGC_ROOT_ANALYSIS) && !defined(JS_THREADSAFE)
if (relax && NeedRelaxedRootChecks())
return;
CheckStackRoots(cx);
#endif
}
namespace gc {
struct Cell;
} /* namespace gc */
/* Base class for automatic read-only object rooting during compilation. */
class CompilerRootNode
{
protected:
CompilerRootNode(js::gc::Cell *ptr) : next(NULL), ptr(ptr) {}
public:
void **address() { return (void **)&ptr; }
public:
CompilerRootNode *next;
protected:
js::gc::Cell *ptr;
};
} /* namespace js */
ForwardDeclareJS(Script);
ForwardDeclareJS(Function);
#endif /* jsgc_root_h___ */
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