Bug 57903 – Introduced the concept of opaque roots, in preparation for marking the DOM with them

• Component: New Bugs
• Status: RESOLVED FIXED

[Geoffrey Garen]

Introduced the concept of opaque roots, in preparation for marking the DOM with them

[Geoffrey Garen]

Created attachment 88333 [details]
Patch

[Oliver Hunt]

Comment on attachment 88333 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=88333&action=review

> Source/JavaScriptCore/collector/handles/HandleHeap.cpp:110
> +            ASSERT(isValidWeakHandle(node->slot()));
> +            JSCell* cell = node->slot()->asCell();
> +            if (Heap::isMarked(cell))
> +                continue;
> +
> +            WeakHandleOwner* weakOwner = node->weakOwner();
> +            if (!weakOwner)
> +                continue;
> +
> +            if (!weakOwner->isReachableFromOpaqueRoots(Handle<Unknown>::wrapSlot(node->slot()), node->weakOwnerContext(), markStack))
> +                continue;
> +
> +            heapRootMarker.mark(node->slot());

I wish we could do something to separate out handles that will remain alive as we enumerate them, otherwise we end up visiting nodes repeatedly (even if just for an isMarked check)

[Geoffrey Garen]

> I wish we could do something to separate out handles that will remain alive as we enumerate them, otherwise we end up visiting nodes repeatedly (even if just for an isMarked check)

This loop almost always executes exactly once, so the tradeoff probably doesn't favor this approach, but:

I think we could optimize by doing an initial pass to separate off the unmarked handles into a temporary linked list. Thereafter, we could iterate only that linked list.

[Build Bot]

Attachment 88333 [details] did not build on win:
Build output: http://queues.webkit.org/results/8346011

[Build Bot]

Attachment 88333 [details] did not build on win:
Build output: http://queues.webkit.org/results/8343016

[Geoffrey Garen]

Committed r83011: <http://trac.webkit.org/changeset/83011>