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axmol/external/spidermonkey/include/win32/js/RootingAPI.h

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/* -*- 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 js_RootingAPI_h
#define js_RootingAPI_h
#include "mozilla/GuardObjects.h"
#include "mozilla/TypeTraits.h"
#include "js/Utility.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 |Rooted| 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.
*
* 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 three 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.
*
* - 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 (measured to
* be a few nanoseconds on desktop) 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.
*
* The following diagram explains the list of supported, implicit type
* conversions between classes of this family:
*
* Rooted<T> ----> Handle<T>
* | ^
* | |
* | |
* +---> MutableHandle<T>
* (via &)
*
* All of these types have an implicit conversion to raw pointers.
*/
namespace js {
class Module;
class ScriptSourceObject;
template <typename T>
struct GCMethods {};
template <typename T>
class RootedBase {};
template <typename T>
class HandleBase {};
template <typename T>
class MutableHandleBase {};
template <typename T>
class HeapBase {};
/*
* js::NullPtr acts like a NULL pointer in contexts that require a Handle.
*
* Handle provides an implicit constructor for js::NullPtr so that, given:
* foo(Handle<JSObject*> h);
* callers can simply write:
* foo(js::NullPtr());
* which avoids creating a Rooted<JSObject*> just to pass NULL.
*
* This is the SpiderMonkey internal variant. js::NullPtr should be used in
* preference to JS::NullPtr to avoid the GOT access required for JS_PUBLIC_API
* symbols.
*/
struct NullPtr
{
static void * const constNullValue;
};
namespace gc {
struct Cell;
} /* namespace gc */
} /* namespace js */
namespace JS {
template <typename T> class Rooted;
template <typename T> class Handle;
template <typename T> class MutableHandle;
/* This is exposing internal state of the GC for inlining purposes. */
JS_FRIEND_API(bool) isGCEnabled();
#if defined(DEBUG) && defined(JS_GC_ZEAL) && defined(JSGC_ROOT_ANALYSIS) && !defined(JS_THREADSAFE)
extern void
CheckStackRoots(JSContext *cx);
#endif
/*
* JS::NullPtr acts like a NULL pointer in contexts that require a Handle.
*
* Handle provides an implicit constructor for JS::NullPtr so that, given:
* foo(Handle<JSObject*> h);
* callers can simply write:
* foo(JS::NullPtr());
* which avoids creating a Rooted<JSObject*> just to pass NULL.
*/
struct JS_PUBLIC_API(NullPtr)
{
static void * const constNullValue;
};
/*
* The Heap<T> class is a C/C++ heap-stored reference to a JS GC thing. All
* members of heap classes that refer to GC thing should use Heap<T> (or
* possibly TenuredHeap<T>, described below).
*
* Heap<T> wraps the complex mechanisms required to ensure GC safety for the
* contained reference into a C++ class that behaves similarly to a normal
* pointer.
*
* GC references stored on the C/C++ stack must use Rooted/Handle/MutableHandle
* instead.
*
* Requirements for type T:
* - Must be one of: Value, jsid, JSObject*, JSString*, JSScript*
*/
template <typename T>
class Heap : public js::HeapBase<T>
{
public:
Heap() {
static_assert(sizeof(T) == sizeof(Heap<T>),
"Heap<T> must be binary compatible with T.");
init(js::GCMethods<T>::initial());
}
explicit Heap(T p) { init(p); }
explicit Heap(const Heap<T> &p) { init(p.ptr); }
~Heap() {
if (js::GCMethods<T>::needsPostBarrier(ptr))
relocate();
}
bool operator==(const Heap<T> &other) { return ptr == other.ptr; }
bool operator!=(const Heap<T> &other) { return ptr != other.ptr; }
bool operator==(const T &other) const { return ptr == other; }
bool operator!=(const T &other) const { return ptr != other; }
operator T() const { return ptr; }
T operator->() const { return ptr; }
const T *address() const { return &ptr; }
const T &get() const { return ptr; }
T *unsafeGet() { return &ptr; }
Heap<T> &operator=(T p) {
set(p);
return *this;
}
void set(T newPtr) {
JS_ASSERT(!js::GCMethods<T>::poisoned(newPtr));
if (js::GCMethods<T>::needsPostBarrier(newPtr)) {
ptr = newPtr;
post();
} else if (js::GCMethods<T>::needsPostBarrier(ptr)) {
relocate(); /* Called before overwriting ptr. */
ptr = newPtr;
} else {
ptr = newPtr;
}
}
private:
void init(T newPtr) {
JS_ASSERT(!js::GCMethods<T>::poisoned(newPtr));
ptr = newPtr;
if (js::GCMethods<T>::needsPostBarrier(ptr))
post();
}
void post() {
#ifdef JSGC_GENERATIONAL
JS_ASSERT(js::GCMethods<T>::needsPostBarrier(ptr));
js::GCMethods<T>::postBarrier(&ptr);
#endif
}
void relocate() {
#ifdef JSGC_GENERATIONAL
js::GCMethods<T>::relocate(&ptr);
#endif
}
T ptr;
};
#ifdef DEBUG
/*
* For generational GC, assert that an object is in the tenured generation as
* opposed to being in the nursery.
*/
extern JS_FRIEND_API(void)
AssertGCThingMustBeTenured(JSObject* obj);
#else
inline void
AssertGCThingMustBeTenured(JSObject *obj) {}
#endif
/*
* The TenuredHeap<T> class is similar to the Heap<T> class above in that it
* encapsulates the GC concerns of an on-heap reference to a JS object. However,
* it has two important differences:
*
* 1) Pointers which are statically known to only reference "tenured" objects
* can avoid the extra overhead of SpiderMonkey's write barriers.
*
* 2) Objects in the "tenured" heap have stronger alignment restrictions than
* those in the "nursery", so it is possible to store flags in the lower
* bits of pointers known to be tenured. TenuredHeap wraps a normal tagged
* pointer with a nice API for accessing the flag bits and adds various
* assertions to ensure that it is not mis-used.
*
* GC things are said to be "tenured" when they are located in the long-lived
* heap: e.g. they have gained tenure as an object by surviving past at least
* one GC. For performance, SpiderMonkey allocates some things which are known
* to normally be long lived directly into the tenured generation; for example,
* global objects. Additionally, SpiderMonkey does not visit individual objects
* when deleting non-tenured objects, so object with finalizers are also always
* tenured; for instance, this includes most DOM objects.
*
* The considerations to keep in mind when using a TenuredHeap<T> vs a normal
* Heap<T> are:
*
* - It is invalid for a TenuredHeap<T> to refer to a non-tenured thing.
* - It is however valid for a Heap<T> to refer to a tenured thing.
* - It is not possible to store flag bits in a Heap<T>.
*/
template <typename T>
class TenuredHeap : public js::HeapBase<T>
{
public:
TenuredHeap() : bits(0) {
static_assert(sizeof(T) == sizeof(TenuredHeap<T>),
"TenuredHeap<T> must be binary compatible with T.");
}
explicit TenuredHeap(T p) : bits(0) { setPtr(p); }
explicit TenuredHeap(const TenuredHeap<T> &p) : bits(0) { setPtr(p.ptr); }
bool operator==(const TenuredHeap<T> &other) { return bits == other.bits; }
bool operator!=(const TenuredHeap<T> &other) { return bits != other.bits; }
void setPtr(T newPtr) {
JS_ASSERT((reinterpret_cast<uintptr_t>(newPtr) & flagsMask) == 0);
JS_ASSERT(!js::GCMethods<T>::poisoned(newPtr));
if (newPtr)
AssertGCThingMustBeTenured(newPtr);
bits = (bits & flagsMask) | reinterpret_cast<uintptr_t>(newPtr);
}
void setFlags(uintptr_t flagsToSet) {
JS_ASSERT((flagsToSet & ~flagsMask) == 0);
bits |= flagsToSet;
}
void unsetFlags(uintptr_t flagsToUnset) {
JS_ASSERT((flagsToUnset & ~flagsMask) == 0);
bits &= ~flagsToUnset;
}
bool hasFlag(uintptr_t flag) const {
JS_ASSERT((flag & ~flagsMask) == 0);
return (bits & flag) != 0;
}
T getPtr() const { return reinterpret_cast<T>(bits & ~flagsMask); }
uintptr_t getFlags() const { return bits & flagsMask; }
operator T() const { return getPtr(); }
T operator->() const { return getPtr(); }
TenuredHeap<T> &operator=(T p) {
setPtr(p);
return *this;
}
/*
* Set the pointer to a value which will cause a crash if it is
* dereferenced.
*/
void setToCrashOnTouch() {
bits = (bits & flagsMask) | crashOnTouchPointer;
}
bool isSetToCrashOnTouch() {
return (bits & ~flagsMask) == crashOnTouchPointer;
}
private:
enum {
maskBits = 3,
flagsMask = (1 << maskBits) - 1,
crashOnTouchPointer = 1 << maskBits
};
uintptr_t bits;
};
/*
* 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 MOZ_NONHEAP_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)
{
static_assert(sizeof(Handle<T>) == sizeof(T *),
"Handle must be binary compatible with T*.");
ptr = reinterpret_cast<const T *>(handle.address());
}
/* Create a handle for a NULL pointer. */
Handle(js::NullPtr) {
static_assert(mozilla::IsPointer<T>::value,
"js::NullPtr overload not valid for non-pointer types");
ptr = reinterpret_cast<const T *>(&js::NullPtr::constNullValue);
}
/* Create a handle for a NULL pointer. */
Handle(JS::NullPtr) {
static_assert(mozilla::IsPointer<T>::value,
"JS::NullPtr overload not valid for non-pointer types");
ptr = reinterpret_cast<const T *>(&JS::NullPtr::constNullValue);
}
Handle(MutableHandle<T> handle) {
ptr = handle.address();
}
/*
* Take care when calling this method!
*
* This creates a Handle from the raw location of a T.
*
* It should be called only if the following conditions hold:
*
* 1) 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.
*
* 2) the contents of the location are immutable, or at least cannot change
* for the lifetime of the handle, as its users may not expect its value
* to change underneath them.
*/
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(const 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; }
const T& get() const { return *ptr; }
/*
* Return a reference so passing a Handle<T> to something that
* takes a |const T&| is not a GC hazard.
*/
operator const T&() const { return get(); }
T operator->() const { return get(); }
bool operator!=(const T &other) const { return *ptr != other; }
bool operator==(const T &other) const { return *ptr == other; }
private:
Handle() {}
const T *ptr;
template <typename S>
void operator=(S v) MOZ_DELETE;
};
typedef Handle<JSObject*> HandleObject;
typedef Handle<js::Module*> HandleModule;
typedef Handle<js::ScriptSourceObject *> HandleScriptSource;
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 MOZ_STACK_CLASS MutableHandle : public js::MutableHandleBase<T>
{
public:
inline MutableHandle(Rooted<T> *root);
void set(T v) {
JS_ASSERT(!js::GCMethods<T>::poisoned(v));
*ptr = 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; }
const T& get() const { return *ptr; }
/*
* Return a reference so passing a MutableHandle<T> to something that takes
* a |const T&| is not a GC hazard.
*/
operator const T&() const { return get(); }
T operator->() const { return get(); }
private:
MutableHandle() {}
T *ptr;
template <typename S> void operator=(S v) MOZ_DELETE;
void operator=(MutableHandle other) 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;
#ifdef JSGC_GENERATIONAL
JS_PUBLIC_API(void) HeapCellPostBarrier(js::gc::Cell **cellp);
JS_PUBLIC_API(void) HeapCellRelocate(js::gc::Cell **cellp);
#endif
} /* namespace JS */
namespace js {
/*
* 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 JS::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))
{}
};
/*
* 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 GCMethods<T *>
{
static T *initial() { return NULL; }
static ThingRootKind kind() { return RootKind<T *>::rootKind(); }
static bool poisoned(T *v) { return JS::IsPoisonedPtr(v); }
static bool needsPostBarrier(T *v) { return v; }
#ifdef JSGC_GENERATIONAL
static void postBarrier(T **vp) {
JS::HeapCellPostBarrier(reinterpret_cast<js::gc::Cell **>(vp));
}
static void relocate(T **vp) {
JS::HeapCellRelocate(reinterpret_cast<js::gc::Cell **>(vp));
}
#endif
};
// XXX: Needed for cocos2d JS Bindings
//#if defined(DEBUG)
/* This helper allows us to assert that Rooted<T> is scoped within a request. */
extern JS_PUBLIC_API(bool)
IsInRequest(JSContext *cx);
//#endif
} /* namespace js */
namespace JS {
/*
* 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 MOZ_STACK_CLASS Rooted : public js::RootedBase<T>
{
/* Note: CX is a subclass of either ContextFriendFields or PerThreadDataFriendFields. */
template <typename CX>
void init(CX *cx) {
#ifdef JSGC_TRACK_EXACT_ROOTS
js::ThingRootKind kind = js::GCMethods<T>::kind();
this->stack = &cx->thingGCRooters[kind];
this->prev = *stack;
*stack = reinterpret_cast<Rooted<void*>*>(this);
JS_ASSERT(!js::GCMethods<T>::poisoned(ptr));
#endif
}
public:
Rooted(JSContext *cx
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(js::GCMethods<T>::initial())
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
MOZ_ASSERT(js::IsInRequest(cx));
init(js::ContextFriendFields::get(cx));
}
Rooted(JSContext *cx, T initial
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(initial)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
MOZ_ASSERT(js::IsInRequest(cx));
init(js::ContextFriendFields::get(cx));
}
Rooted(js::ContextFriendFields *cx
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(js::GCMethods<T>::initial())
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(cx);
}
Rooted(js::ContextFriendFields *cx, T initial
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(initial)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(cx);
}
Rooted(js::PerThreadDataFriendFields *pt
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(js::GCMethods<T>::initial())
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(pt);
}
Rooted(js::PerThreadDataFriendFields *pt, T initial
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(initial)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(pt);
}
Rooted(JSRuntime *rt
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(js::GCMethods<T>::initial())
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(js::PerThreadDataFriendFields::getMainThread(rt));
}
Rooted(JSRuntime *rt, T initial
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(initial)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
init(js::PerThreadDataFriendFields::getMainThread(rt));
}
~Rooted() {
#ifdef JSGC_TRACK_EXACT_ROOTS
JS_ASSERT(*stack == reinterpret_cast<Rooted<void*>*>(this));
*stack = prev;
#endif
}
#ifdef JSGC_TRACK_EXACT_ROOTS
Rooted<T> *previous() { return prev; }
#endif
/*
* Important: Return a reference here so passing a Rooted<T> to
* something that takes a |const T&| is not a GC hazard.
*/
operator const 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(!js::GCMethods<T>::poisoned(value));
ptr = value;
return ptr;
}
T &operator=(const Rooted &value) {
ptr = value;
return ptr;
}
void set(T value) {
JS_ASSERT(!js::GCMethods<T>::poisoned(value));
ptr = value;
}
bool operator!=(const T &other) const { return ptr != other; }
bool operator==(const T &other) const { return ptr == other; }
private:
#ifdef JSGC_TRACK_EXACT_ROOTS
Rooted<void*> **stack, *prev;
#endif
#if defined(DEBUG) && defined(JS_GC_ZEAL) && defined(JSGC_ROOT_ANALYSIS) && !defined(JS_THREADSAFE)
/* Has the rooting analysis ever scanned this Rooted's stack location? */
friend void JS::CheckStackRoots(JSContext*);
#endif
#ifdef JSGC_ROOT_ANALYSIS
bool scanned;
#endif
/*
* |ptr| must be the last field in Rooted because the analysis treats all
* Rooted as Rooted<void*> during the analysis. See bug 829372.
*/
T ptr;
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
Rooted(const Rooted &) MOZ_DELETE;
};
#if !(defined(JSGC_ROOT_ANALYSIS) || defined(JSGC_USE_EXACT_ROOTING))
// Defined in vm/String.h.
template <>
class Rooted<JSStableString *>;
#endif
typedef Rooted<JSObject*> RootedObject;
typedef Rooted<js::Module*> RootedModule;
typedef Rooted<js::ScriptSourceObject *> RootedScriptSource;
typedef Rooted<JSFunction*> RootedFunction;
typedef Rooted<JSScript*> RootedScript;
typedef Rooted<JSString*> RootedString;
typedef Rooted<jsid> RootedId;
typedef Rooted<JS::Value> RootedValue;
} /* namespace JS */
namespace js {
/*
* 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 CX, typename T>
void init(CX *cx, const T *ptr, size_t count) {
SkipRoot **head = &cx->skipGCRooters;
this->stack = head;
this->prev = *stack;
*stack = this;
this->start = (const uint8_t *) ptr;
this->end = this->start + (sizeof(T) * count);
}
public:
~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 */
template <typename T>
void init(js::ContextFriendFields *cx, const T *ptr, size_t count) {}
public:
#endif /* DEBUG && JSGC_ROOT_ANALYSIS */
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;
}
template <typename T>
SkipRoot(ContextFriendFields *cx, const T *ptr, size_t count = 1
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
{
init(cx, ptr, count);
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
}
template <typename T>
SkipRoot(PerThreadData *pt, const T *ptr, size_t count = 1
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
{
init(PerThreadDataFriendFields::get(pt), ptr, count);
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
}
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
};
/* Interface substitute for Rooted<T> which does not root the variable's memory. */
template <typename T>
class FakeRooted : public RootedBase<T>
{
public:
template <typename CX>
FakeRooted(CX *cx
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(GCMethods<T>::initial())
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
}
template <typename CX>
FakeRooted(CX *cx, T initial
MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: ptr(initial)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
}
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(!GCMethods<T>::poisoned(value));
ptr = value;
return ptr;
}
bool operator!=(const T &other) const { return ptr != other; }
bool operator==(const T &other) const { return ptr == other; }
private:
T ptr;
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
FakeRooted(const FakeRooted &) MOZ_DELETE;
};
/* Interface substitute for MutableHandle<T> which is not required to point to rooted memory. */
template <typename T>
class FakeMutableHandle : public js::MutableHandleBase<T>
{
public:
FakeMutableHandle(T *t) {
ptr = t;
}
FakeMutableHandle(FakeRooted<T> *root) {
ptr = root->address();
}
void set(T v) {
JS_ASSERT(!js::GCMethods<T>::poisoned(v));
*ptr = v;
}
T *address() const { return ptr; }
T get() const { return *ptr; }
operator T() const { return get(); }
T operator->() const { return get(); }
private:
FakeMutableHandle() {}
T *ptr;
template <typename S>
void operator=(S v) MOZ_DELETE;
};
/*
* Types for a variable that either should or shouldn't be rooted, depending on
* the template parameter Rooted. Used for implementing functions that can
* operate on either rooted or unrooted data.
*
* The toHandle() and toMutableHandle() functions are for calling functions
* which require handle types and are only called in the CanGC case. These
* allow the calling code to type check.
*/
enum AllowGC {
NoGC = 0,
CanGC = 1
};
template <typename T, AllowGC allowGC>
class MaybeRooted
{
};
template <typename T> class MaybeRooted<T, CanGC>
{
public:
typedef JS::Handle<T> HandleType;
typedef JS::Rooted<T> RootType;
typedef JS::MutableHandle<T> MutableHandleType;
static inline JS::Handle<T> toHandle(HandleType v) {
return v;
}
static inline JS::MutableHandle<T> toMutableHandle(MutableHandleType v) {
return v;
}
};
template <typename T> class MaybeRooted<T, NoGC>
{
public:
typedef T HandleType;
typedef FakeRooted<T> RootType;
typedef FakeMutableHandle<T> MutableHandleType;
static inline JS::Handle<T> toHandle(HandleType v) {
MOZ_ASSUME_UNREACHABLE("Bad conversion");
}
static inline JS::MutableHandle<T> toMutableHandle(MutableHandleType v) {
MOZ_ASSUME_UNREACHABLE("Bad conversion");
}
};
} /* namespace js */
namespace JS {
template <typename T> template <typename S>
inline
Handle<T>::Handle(const 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>
inline
MutableHandle<T>::MutableHandle(Rooted<T> *root)
{
static_assert(sizeof(MutableHandle<T>) == sizeof(T *),
"MutableHandle must be binary compatible with T*.");
ptr = root->address();
}
} /* 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)
{
#if defined(DEBUG) && defined(JS_GC_ZEAL) && defined(JSGC_ROOT_ANALYSIS) && !defined(JS_THREADSAFE)
JS::CheckStackRoots(cx);
#endif
}
/* 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 */
#endif /* js_RootingAPI_h */
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