Speed up arguments object

Don't fully create the arguments object unless required.
In the 95% use case, we can avoid creating any array based
data structures for the arguments object and directly
manipulate the functions arguments. only create the full
data structure for the other 5%.

Speeds up the raytrace test by 50%, gives around 10% overall
on v8-bench.

Change-Id: If727d28b96585e83314f544031a6c3ca1817ea19
Reviewed-by: Simon Hausmann <[email protected]>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/qml/jsruntime/qv4objectiterator.cpp b/src/qml/jsruntime/qv4objectiterator.cpp
index 62595b5176..04fa504991 100644
--- a/src/qml/jsruntime/qv4objectiterator.cpp
+++ b/src/qml/jsruntime/qv4objectiterator.cpp
@@ -42,6 +42,7 @@
 #include "qv4object_p.h"
 #include "qv4stringobject_p.h"
 #include "qv4identifier_p.h"
+#include "qv4argumentsobject_p.h"
 
 using namespace QV4;
 
@@ -56,6 +57,11 @@ ObjectIterator::ObjectIterator(SafeObject *scratch1, SafeObject *scratch2, const
     object = o;
     current = o;
     tmpDynamicProperty.value = Primitive::undefinedValue();
+
+    if (object && object->isNonStrictArgumentsObject) {
+        Scope scope(object->engine());
+        Scoped<ArgumentsObject> (scope, object->asReturnedValue())->fullyCreate();
+    }
 }
 
 ObjectIterator::ObjectIterator(Scope &scope, const ObjectRef o, uint flags)
@@ -69,6 +75,11 @@ ObjectIterator::ObjectIterator(Scope &scope, const ObjectRef o, uint flags)
     object = o;
     current = o;
     tmpDynamicProperty.value = Primitive::undefinedValue();
+
+    if (object && object->isNonStrictArgumentsObject) {
+        Scope scope(object->engine());
+        Scoped<ArgumentsObject> (scope, object->asReturnedValue())->fullyCreate();
+    }
 }
 
 Property *ObjectIterator::next(StringRef name, uint *index, PropertyAttributes *attrs)