Xidorn Quan [:xidorn] UTC+11 Reporter
	Description • 7 years ago

Gecko_GetDocumentLWTheme and ThreadSafeGetDocumentLWTheme shows up in profiles for tpaint with several samples.

Looking at them, I think it makes sense to initialize XULDocument::mDocLWTheme as soon as possible, and avoid querying attribute during traversal. It can probably happen in nsXULElement::BindToTree.

It seems that we already re-evaluate mDocLWTheme every time the relevant attribute is changed, so I guess as far as we have the field initialized properly at the beginning, we don't need a separate ThreadSafeGetDocumentLWTheme method for that, and can assert when we query it, the field has been set.

With that, we can inlinize the whole Gecko_GetDocumentLWTheme into Servo side with just a document type check, a type cast, and a field access. We may need to generate bindings for XULDocument, though.

Not sure whether it's worth. It seems to only take like 0.1% of time in tpaint.