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Unify layout of function objects 

Ensure we have the proto property at always the same place.
This will be used in a subsequent commit to optimize accesses
to the prototype property e.g. when doing instanceof
operations or constructor calls.

Change-Id: I6e9a19e0b7d0e8ab583648a60d1978f5cf838b06
Reviewed-by: Erik Verbruggen <erik.verbruggen@qt.io>
This commit is contained in:
Lars Knoll 2018-09-19 15:27:41 +02:00
parent 9df44b2b50
commit 7c59262503
3 changed files with 19 additions and 12 deletions
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18
src/qml/jsruntime/qv4engine.cpp
View File

@ -351,23 +351,29 @@ ExecutionEngine::ExecutionEngine(QJSEngine *jsEngine)
jsObjects[FunctionProto] = memoryManager->allocObject<FunctionPrototype>(ic->d());
ic = newInternalClass(FunctionObject::staticVTable(), functionPrototype());
classes[Class_FunctionObject] = ic->d();
// Add an invalid prototype slot, so that all function objects have the same layout
// This helps speed up instanceof operations and other things where we need to query
// prototype property (as we always know it's location)
ic = ic->addMember(id_prototype()->propertyKey(), Attr_Invalid, index);
Q_ASSERT(index->index == Heap::FunctionObject::Index_Prototype);
ic = ic->addMember(id_name()->propertyKey(), Attr_ReadOnly, index);
Q_ASSERT(index->index == Heap::ArrowFunction::Index_Name);
ic = ic->addMember(id_length()->propertyKey(), Attr_ReadOnly_ButConfigurable, index);
Q_ASSERT(index->index == Heap::ArrowFunction::Index_Length);
classes[Class_ArrowFunction] = ic->changeVTable(ArrowFunction::staticVTable());
ic = ic->changeVTable(ScriptFunction::staticVTable());
classes[Class_ScriptFunction] = ic->d();
ic = ic->changeVTable(ConstructorFunction::staticVTable());
classes[Class_ConstructorFunction] = ic->d();
ic = ic->changeVTable(MemberFunction::staticVTable());
classes[Class_MemberFunction] = ic->d();
ic = ic->changeVTable(GeneratorFunction::staticVTable());
classes[Class_MemberFunction] = ic->d();
ic = ic->changeVTable(GeneratorFunction::staticVTable());
classes[Class_GeneratorFunction] = ic->d();
ic = ic->changeVTable(MemberGeneratorFunction::staticVTable());
classes[Class_MemberGeneratorFunction] = ic->d();
ic = ic->changeMember(id_prototype()->propertyKey(), Attr_NotConfigurable|Attr_NotEnumerable);
ic = ic->changeVTable(ScriptFunction::staticVTable());
classes[Class_ScriptFunction] = ic->d();
ic = ic->changeVTable(ConstructorFunction::staticVTable());
classes[Class_ConstructorFunction] = ic->d();
classes[Class_ObjectProto] = classes[Class_Object]->addMember(id_constructor()->propertyKey(), Attr_NotEnumerable, index);
Q_ASSERT(index->index == Heap::FunctionObject::Index_ProtoConstructor);

9
src/qml/jsruntime/qv4functionobject_p.h
View File

@ -76,7 +76,8 @@ namespace Heap {
DECLARE_HEAP_OBJECT(FunctionObject, Object) {
DECLARE_MARKOBJECTS(FunctionObject);
enum {
Index_ProtoConstructor = 0
Index_ProtoConstructor = 0,
Index_Prototype = 0
};
bool isConstructor() const {
@ -111,7 +112,7 @@ struct IndexedBuiltinFunction : FunctionObject {
struct ArrowFunction : FunctionObject {
enum {
Index_Name,
Index_Name = Index_Prototype + 1,
Index_Length
};
void init(QV4::ExecutionContext *scope, Function *function, QV4::String *name = nullptr);
@ -122,10 +123,6 @@ struct ArrowFunction : FunctionObject {
DECLARE_HEAP_OBJECT(ScriptFunction, ArrowFunction) {
DECLARE_MARKOBJECTS(ScriptFunction)
enum {
Index_Name,
Index_Length
};
void init(QV4::ExecutionContext *scope, Function *function);
};

4
src/qml/jsruntime/qv4managed_p.h
View File

@ -233,6 +233,10 @@ struct InternalClass : Managed
return d()->addMember(identifier, data, entry);
}
Q_REQUIRED_RESULT Heap::InternalClass *changeMember(PropertyKey identifier, PropertyAttributes data, InternalClassEntry *entry = nullptr) {
return d()->changeMember(identifier, data, entry);
}
void operator =(Heap::InternalClass *ic) {
Value::operator=(ic);
}