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Bug 1157703 - Cache iterators involving unboxed objects, r=jandem.

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This commit is contained in:
Brian Hackett
2015-05-03 15:27:12 -07:00
parent 8016bfddd7
commit 9fd6f781f1
11 changed files with 392 additions and 282 deletions
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123
js/src/jsiter.cpp
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@@ -62,6 +62,9 @@ NativeIterator::mark(JSTracer* trc)
if (obj)
TraceEdge(trc, &obj, "obj");
for (size_t i = 0; i < guard_length; i++)
guard_array[i].trace(trc);
// The SuppressDeletedPropertyHelper loop can GC, so make sure that if the
// GC removes any elements from the list, it won't remove this one.
if (iterObj_)
@@ -531,10 +534,12 @@ NewPropertyIteratorObject(JSContext* cx, unsigned flags)
}
NativeIterator*
NativeIterator::allocateIterator(JSContext* cx, uint32_t slength, const AutoIdVector& props)
NativeIterator::allocateIterator(JSContext* cx, uint32_t numGuards, const AutoIdVector& props)
{
JS_STATIC_ASSERT(sizeof(ReceiverGuard) == 2 * sizeof(void*));
size_t plength = props.length();
NativeIterator* ni = cx->zone()->pod_malloc_with_extra<NativeIterator, void*>(plength + slength);
NativeIterator* ni = cx->zone()->pod_malloc_with_extra<NativeIterator, void*>(plength + numGuards * 2);
if (!ni)
return nullptr;
@@ -572,14 +577,14 @@ NativeIterator::allocateSentinel(JSContext* maybecx)
}
inline void
NativeIterator::init(JSObject* obj, JSObject* iterObj, unsigned flags, uint32_t slength, uint32_t key)
NativeIterator::init(JSObject* obj, JSObject* iterObj, unsigned flags, uint32_t numGuards, uint32_t key)
{
this->obj.init(obj);
this->iterObj_ = iterObj;
this->flags = flags;
this->shapes_array = (Shape**) this->props_end;
this->shapes_length = slength;
this->shapes_key = key;
this->guard_array = (HeapReceiverGuard*) this->props_end;
this->guard_length = numGuards;
this->guard_key = key;
}
static inline void
@@ -596,7 +601,7 @@ RegisterEnumerator(JSContext* cx, PropertyIteratorObject* iterobj, NativeIterato
static inline bool
VectorToKeyIterator(JSContext* cx, HandleObject obj, unsigned flags, AutoIdVector& keys,
uint32_t slength, uint32_t key, MutableHandleObject objp)
uint32_t numGuards, uint32_t key, MutableHandleObject objp)
{
MOZ_ASSERT(!(flags & JSITER_FOREACH));
@@ -608,26 +613,20 @@ VectorToKeyIterator(JSContext* cx, HandleObject obj, unsigned flags, AutoIdVecto
if (!iterobj)
return false;
NativeIterator* ni = NativeIterator::allocateIterator(cx, slength, keys);
NativeIterator* ni = NativeIterator::allocateIterator(cx, numGuards, keys);
if (!ni)
return false;
ni->init(obj, iterobj, flags, slength, key);
ni->init(obj, iterobj, flags, numGuards, key);
if (slength) {
/*
* Fill in the shape array from scratch. We can't use the array that was
* computed for the cache lookup earlier, as constructing iterobj could
* have triggered a shape-regenerating GC. Don't bother with regenerating
* the shape key; if such a GC *does* occur, we can only get hits through
* the one-slot lastNativeIterator cache.
*/
if (numGuards) {
// Fill in the guard array from scratch.
JSObject* pobj = obj;
size_t ind = 0;
do {
ni->shapes_array[ind++] = pobj->as<NativeObject>().lastProperty();
ni->guard_array[ind++].init(ReceiverGuard(pobj));
pobj = pobj->getProto();
} while (pobj);
MOZ_ASSERT(ind == slength);
MOZ_ASSERT(ind == numGuards);
}
iterobj->setNativeIterator(ni);
@@ -702,6 +701,37 @@ UpdateNativeIterator(NativeIterator* ni, JSObject* obj)
ni->obj = obj;
}
static inline bool
CanCompareIterableObjectToCache(JSObject* obj)
{
if (obj->isNative())
return obj->as<NativeObject>().hasEmptyElements();
if (obj->is<UnboxedPlainObject>()) {
if (UnboxedExpandoObject* expando = obj->as<UnboxedPlainObject>().maybeExpando())
return expando->hasEmptyElements();
return true;
}
return false;
}
static inline bool
CanCacheIterableObject(JSContext* cx, JSObject* obj)
{
if (!CanCompareIterableObjectToCache(obj))
return false;
if (obj->isNative()) {
if (IsAnyTypedArray(obj) ||
obj->hasUncacheableProto() ||
obj->getOps()->enumerate ||
obj->getClass()->enumerate ||
obj->as<NativeObject>().containsPure(cx->names().iteratorIntrinsic))
{
return false;
}
}
return true;
}
bool
js::GetIterator(JSContext* cx, HandleObject obj, unsigned flags, MutableHandleObject objp)
{
@@ -720,27 +750,21 @@ js::GetIterator(JSContext* cx, HandleObject obj, unsigned flags, MutableHandleOb
return Proxy::enumerate(cx, obj, objp);
}
Vector<Shape*, 8> shapes(cx);
Vector<ReceiverGuard, 8> guards(cx);
uint32_t key = 0;
if (flags == JSITER_ENUMERATE) {
/*
* Check to see if this is the same as the most recent object which
* was iterated over. We don't explicitly check for shapeless
* objects here, as they are not inserted into the cache and
* will result in a miss.
*/
// Check to see if this is the same as the most recent object which was
// iterated over.
PropertyIteratorObject* last = cx->runtime()->nativeIterCache.last;
if (last) {
NativeIterator* lastni = last->getNativeIterator();
if (!(lastni->flags & (JSITER_ACTIVE|JSITER_UNREUSABLE)) &&
obj->isNative() &&
obj->as<NativeObject>().hasEmptyElements() &&
obj->as<NativeObject>().lastProperty() == lastni->shapes_array[0])
CanCompareIterableObjectToCache(obj) &&
ReceiverGuard(obj) == lastni->guard_array[0])
{
JSObject* proto = obj->getProto();
if (proto->isNative() &&
proto->as<NativeObject>().hasEmptyElements() &&
proto->as<NativeObject>().lastProperty() == lastni->shapes_array[1] &&
if (CanCompareIterableObjectToCache(proto) &&
ReceiverGuard(proto) == lastni->guard_array[1] &&
!proto->getProto())
{
objp.set(last);
@@ -760,20 +784,13 @@ js::GetIterator(JSContext* cx, HandleObject obj, unsigned flags, MutableHandleOb
{
JSObject* pobj = obj;
do {
if (!pobj->isNative() ||
!pobj->as<NativeObject>().hasEmptyElements() ||
IsAnyTypedArray(pobj) ||
pobj->hasUncacheableProto() ||
pobj->getOps()->enumerate ||
pobj->getClass()->enumerate ||
pobj->as<NativeObject>().containsPure(cx->names().iteratorIntrinsic))
{
shapes.clear();
if (!CanCacheIterableObject(cx, pobj)) {
guards.clear();
goto miss;
}
Shape* shape = pobj->as<NativeObject>().lastProperty();
key = (key + (key << 16)) ^ (uintptr_t(shape) >> 3);
if (!shapes.append(shape))
ReceiverGuard guard(pobj);
key = (key + (key << 16)) ^ guard.hash();
if (!guards.append(guard))
return false;
pobj = pobj->getProto();
} while (pobj);
@@ -783,14 +800,16 @@ js::GetIterator(JSContext* cx, HandleObject obj, unsigned flags, MutableHandleOb
if (iterobj) {
NativeIterator* ni = iterobj->getNativeIterator();
if (!(ni->flags & (JSITER_ACTIVE|JSITER_UNREUSABLE)) &&
ni->shapes_key == key &&
ni->shapes_length == shapes.length() &&
Compare(ni->shapes_array, shapes.begin(), ni->shapes_length)) {
ni->guard_key == key &&
ni->guard_length == guards.length() &&
Compare(reinterpret_cast<ReceiverGuard*>(ni->guard_array),
guards.begin(), ni->guard_length))
{
objp.set(iterobj);
UpdateNativeIterator(ni, obj);
RegisterEnumerator(cx, iterobj, ni);
if (shapes.length() == 2)
if (guards.length() == 2)
cx->runtime()->nativeIterCache.last = iterobj;
return true;
}
@@ -805,7 +824,7 @@ js::GetIterator(JSContext* cx, HandleObject obj, unsigned flags, MutableHandleOb
AutoIdVector keys(cx);
if (flags & JSITER_FOREACH) {
MOZ_ASSERT(shapes.empty());
MOZ_ASSERT(guards.empty());
if (!Snapshot(cx, obj, flags, &keys))
return false;
@@ -814,17 +833,17 @@ js::GetIterator(JSContext* cx, HandleObject obj, unsigned flags, MutableHandleOb
} else {
if (!Snapshot(cx, obj, flags, &keys))
return false;
if (!VectorToKeyIterator(cx, obj, flags, keys, shapes.length(), key, objp))
if (!VectorToKeyIterator(cx, obj, flags, keys, guards.length(), key, objp))
return false;
}
PropertyIteratorObject* iterobj = &objp->as<PropertyIteratorObject>();
/* Cache the iterator object if possible. */
if (shapes.length())
if (guards.length())
cx->runtime()->nativeIterCache.set(key, iterobj);
if (shapes.length() == 2)
if (guards.length() == 2)
cx->runtime()->nativeIterCache.last = iterobj;
return true;
}