Move extensible into the internal class

With this, we can now save one pointer per Heap
object.

Change-Id: I7f69193ff51c9fd9c5dbfba90aa1ebb3f93da2e6
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

5 files changed, 32 insertions, 23 deletions

diff --git a/src/qml/jsruntime/qv4internalclass.cpp b/src/qml/jsruntime/qv4internalclass.cpp
index 8c44d65426..2115ee09a0 100644
--- a/src/qml/jsruntime/qv4internalclass.cpp
+++ b/src/qml/jsruntime/qv4internalclass.cpp
@@ -116,6 +116,7 @@ InternalClass::InternalClass(ExecutionEngine *engine)
     , m_sealed(0)
     , m_frozen(0)
     , size(0)
+    , extensible(true)
 {
 }
 
@@ -130,7 +131,9 @@ InternalClass::InternalClass(const QV4::InternalClass &other)
     , m_sealed(0)
     , m_frozen(0)
     , size(other.size)
+    , extensible(other.extensible)
 {
+    Q_ASSERT(extensible);
 }
 
 void InternalClass::changeMember(Object *object, String *string, PropertyAttributes data, uint *index)
@@ -228,6 +231,27 @@ InternalClass *InternalClass::changeVTable(const ManagedVTable *vt)
     return newClass;
 }
 
+InternalClass *InternalClass::nonExtensible()
+{
+    if (!extensible)
+        return this;
+
+    Transition temp;
+    temp.vtable = 0;
+    temp.lookup = 0;
+    temp.flags = Transition::NotExtensible;
+
+    Transition &t = lookupOrInsertTransition(temp);
+    if (t.lookup)
+        return t.lookup;
+
+    InternalClass *newClass = engine->newClass(*this);
+    newClass->extensible = false;
+
+    t.lookup = newClass;
+    return newClass;
+}
+
 void InternalClass::addMember(Object *object, String *string, PropertyAttributes data, uint *index)
 {
     data.resolve();
@@ -357,6 +381,7 @@ InternalClass *InternalClass::sealed()
         attrs.setConfigurable(false);
         m_sealed = m_sealed->addMember(nameMap.at(i), attrs);
     }
+    m_sealed = m_sealed->nonExtensible();
 
     m_sealed->m_sealed = m_sealed;
     return m_sealed;
@@ -377,6 +402,7 @@ InternalClass *InternalClass::frozen()
         attrs.setConfigurable(false);
         m_frozen = m_frozen->addMember(nameMap.at(i), attrs);
     }
+    m_frozen = m_frozen->nonExtensible();
 
     m_frozen->m_frozen = m_frozen;
     m_frozen->m_sealed = m_frozen;
diff --git a/src/qml/jsruntime/qv4internalclass_p.h b/src/qml/jsruntime/qv4internalclass_p.h
index 5973ca2c7c..b92bee3fac 100644
--- a/src/qml/jsruntime/qv4internalclass_p.h
+++ b/src/qml/jsruntime/qv4internalclass_p.h
@@ -197,7 +197,8 @@ struct InternalClassTransition
     int flags;
     enum {
         // range 0-0xff is reserved for attribute changes
-        VTableChange = 0x100
+        VTableChange = 0x100,
+        NotExtensible = 0x200
     };
 
     bool operator==(const InternalClassTransition &other) const
@@ -223,9 +224,11 @@ struct InternalClass : public QQmlJS::Managed {
     InternalClass *m_frozen;
 
     uint size;
+    bool extensible;
 
     static InternalClass *create(ExecutionEngine *engine, const ManagedVTable *vtable);
     InternalClass *changeVTable(const ManagedVTable *vt);
+    InternalClass *nonExtensible();
     static void addMember(Object *object, String *string, PropertyAttributes data, uint *index);
     InternalClass *addMember(String *string, PropertyAttributes data, uint *index = 0);
     InternalClass *addMember(Identifier *identifier, PropertyAttributes data, uint *index = 0);
diff --git a/src/qml/jsruntime/qv4object_p.h b/src/qml/jsruntime/qv4object_p.h
index a38750dd07..298779906b 100644
--- a/src/qml/jsruntime/qv4object_p.h
+++ b/src/qml/jsruntime/qv4object_p.h
@@ -140,8 +140,7 @@ struct Q_QML_EXPORT Object: Managed {
 
     inline ExecutionEngine *engine() const { return internalClass()->engine; }
 
-    bool isExtensible() const { return d()->extensible; }
-    void setExtensible(bool b) { d()->extensible = b; }
+    bool isExtensible() const { return d()->internalClass->extensible; }
 
     // Array handling
 
diff --git a/src/qml/jsruntime/qv4objectproto.cpp b/src/qml/jsruntime/qv4objectproto.cpp
index 34a9b9cb64..445d4f7a68 100644
--- a/src/qml/jsruntime/qv4objectproto.cpp
+++ b/src/qml/jsruntime/qv4objectproto.cpp
@@ -244,8 +244,6 @@ ReturnedValue ObjectPrototype::method_seal(CallContext *ctx)
     if (!o)
         return ctx->engine()->throwTypeError();
 
-    o->setExtensible(false);
-
     o->setInternalClass(o->internalClass()->sealed());
 
     if (o->arrayData()) {
@@ -269,8 +267,6 @@ ReturnedValue ObjectPrototype::method_freeze(CallContext *ctx)
     if (ArgumentsObject::isNonStrictArgumentsObject(o))
         Scoped<ArgumentsObject>(scope, o)->fullyCreate();
 
-    o->setExtensible(false);
-
     o->setInternalClass(o->internalClass()->frozen());
 
     if (o->arrayData()) {
@@ -292,7 +288,7 @@ ReturnedValue ObjectPrototype::method_preventExtensions(CallContext *ctx)
     if (!o)
         return ctx->engine()->throwTypeError();
 
-    o->setExtensible(false);
+    o->setInternalClass(o->internalClass()->nonExtensible());
     return o.asReturnedValue();
 }
 
diff --git a/src/qml/jsruntime/qv4value_p.h b/src/qml/jsruntime/qv4value_p.h
index 31db8a21c5..526cb01ac4 100644
--- a/src/qml/jsruntime/qv4value_p.h
+++ b/src/qml/jsruntime/qv4value_p.h
@@ -50,7 +50,6 @@ struct Q_QML_EXPORT Base {
     Base() {}
     Base(InternalClass *internal)
         : internalClass(internal)
-        , extensible(1)
     {
         Q_ASSERT(inUse() && !isMarked());
         // ####
@@ -60,20 +59,6 @@ struct Q_QML_EXPORT Base {
         InternalClass *internalClass;
         quintptr mm_data;
     };
-    struct {
-        uchar _markBit :  1;
-        uchar _inUse   :  1;
-        uchar extensible : 1; // used by Object
-        uchar _needsActivation : 1; // used by FunctionObject
-        uchar _strictMode : 1; // used by FunctionObject
-        uchar _bindingKeyFlag : 1;
-        uchar _hasAccessorProperty : 1;
-        uchar _unused : 1;
-        mutable uchar _subtype;
-        uchar _unused2;
-        uchar _unused3;
-
-    };
 
     void setVTable(const ManagedVTable *vt);
     inline ReturnedValue asReturnedValue() const;