Move the internalClass field from Heap::Object to Heap::Base

And do not store the vtable in Heap::Base anymore. This change
makes the internal class the main distinguishing feature
of all garbage collected objects.

It also saves one pointer on all Objects. No measurable
impact on runtime performance.

Change-Id: I040a28b7581b993f1886b5219e279173dfa567e8
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 12 insertions, 5 deletions

diff --git a/src/qml/memory/qv4mm_p.h b/src/qml/memory/qv4mm_p.h
index 9b4c2cd8df..8f12fa7cbd 100644
--- a/src/qml/memory/qv4mm_p.h
+++ b/src/qml/memory/qv4mm_p.h
@@ -210,7 +210,8 @@ public:
     {
         Heap::CallContext *ctxt = stackAllocator.allocate();
         memset(ctxt, 0, sizeof(Heap::CallContext));
-        ctxt->setVtable(QV4::CallContext::staticVTable());
+        ctxt->internalClass = CallContext::defaultInternalClass(engine);
+        Q_ASSERT(ctxt->internalClass && ctxt->internalClass->vtable);
         ctxt->init(v4);
         return ctxt;
 
@@ -224,7 +225,10 @@ public:
         V4_ASSERT_IS_TRIVIAL(typename ManagedType::Data)
         size = align(size);
         Heap::Base *o = allocData(size);
-        o->setVtable(ManagedType::staticVTable());
+        InternalClass *ic = ManagedType::defaultInternalClass(engine);
+        ic = ic->changeVTable(ManagedType::staticVTable());
+        o->internalClass = ic;
+        Q_ASSERT(o->internalClass && o->internalClass->vtable);
         return static_cast<typename ManagedType::Data *>(o);
     }
 
@@ -232,8 +236,9 @@ public:
     typename ObjectType::Data *allocateObject(InternalClass *ic)
     {
         Heap::Object *o = allocObjectWithMemberData(ObjectType::staticVTable(), ic->size);
-        o->setVtable(ObjectType::staticVTable());
         o->internalClass = ic;
+        Q_ASSERT(o->internalClass && o->internalClass->vtable);
+        Q_ASSERT(ic->vtable == ObjectType::staticVTable());
         return static_cast<typename ObjectType::Data *>(o);
     }
 
@@ -241,10 +246,11 @@ public:
     typename ObjectType::Data *allocateObject()
     {
         InternalClass *ic = ObjectType::defaultInternalClass(engine);
+        ic = ic->changeVTable(ObjectType::staticVTable());
         Heap::Object *o = allocObjectWithMemberData(ObjectType::staticVTable(), ic->size);
-        o->setVtable(ObjectType::staticVTable());
         Object *prototype = ObjectType::defaultPrototype(engine);
         o->internalClass = ic;
+        Q_ASSERT(o->internalClass && o->internalClass->vtable);
         o->prototype = prototype->d();
         return static_cast<typename ObjectType::Data *>(o);
     }
@@ -253,7 +259,8 @@ public:
     typename ManagedType::Data *allocWithStringData(std::size_t unmanagedSize, Arg1 arg1)
     {
         typename ManagedType::Data *o = reinterpret_cast<typename ManagedType::Data *>(allocString(unmanagedSize));
-        o->setVtable(ManagedType::staticVTable());
+        o->internalClass = ManagedType::defaultInternalClass(engine);
+        Q_ASSERT(o->internalClass && o->internalClass->vtable);
         o->init(this, arg1);
         return o;
     }