Bug 67690 – Remove virtual functions from JSCell

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Mark Hahnenberg]

In order to maintain more control over exactly how JS objects are laid out, we need to remove the C++ virtual functions from JS object implementations due to the freedom that C++ compilers are given with how they lay out objects with vtable pointers.  We can also save a little bit of memory due to the lack of vtable pointer in each object.  The methods in JSCell that either need to be made non-virtual or removed are the following:

isGetterSetter
isAPIValueWrapper
isPropertyNameIterator
getCallData
getConstructData
getUInt32
toPrimitive
getPrimitive
toBoolean
toNumber
toString
toObject
visitChildren
put(ExecState*, const Identifier&, JSValue, PutPropertySlot&)
put(ExecState*, unsigned, JSValue)
deleteProperty(ExecState*, const Identifier&)
deleteProperty(ExecState*, unsigned)
toThisObject
getJSNumber
getOwnPropertySlot(ExecState*, const Identifier&, PropertySlot&)
getOwnPropertySlot(ExecState*, unsigned, PropertySlot&)

Destructors will be taken care of by Oliver :-)  There will be a patch for each function, roughly.  This will serve as the tracking bug for this task.

[Mark Hahnenberg]

Sam helped me out a little bit and de-virtualized isGetterSetter, isAPIValueWrapper, and killed isPropertyNameIterator :-)

[Mark Hahnenberg]

Except the virtual destructor, which will remain for a while longer until we get around to replacing virtual destructors with finalizers, there are no longer any virtual functions in JSCell.  Closing this bug.