Bug 79299 – Type tags in NodeFlags could be compressed

• Component: DOM
• Status: RESOLVED LATER

[Hajime Morrita]

We have type tags like:

        IsTextFlag = 1,
        IsCommentFlag = 1 << 1,
        IsContainerFlag = 1 << 2,
        IsElementFlag = 1 << 3,
        IsStyledElementFlag = 1 << 4,
        IsHTMLFlag = 1 << 5,
        IsSVGFlag = 1 << 6,
        InDocumentFlag = 1 << 9,
        IsShadowRootOrSVGShadowRootFlag = 1 << 16,

And these are apparently redundant. We could compress these.

[Antti Koivisto]

(In reply to comment #0)
>         InDocumentFlag = 1 << 9,

This one is not redundant.

[Hajime Morrita]

Created attachment 137289 [details]
Patch

[Hajime Morrita]

As Ryosuke's request at #webkit, I took two bencharks from Dromaeo which hit DOM heavily:

dom-modify:     before            after
avg                3,816.93     3,819.05
stdev                  44.37          90.98

dom-traverse:      before            after
avg                  2,472.91     2,520.09
stdev                    62.35          48.05

The lager number is better.
This even shows a tiny improvement. But it's unlikely. It will be just a noise.
I think we can say that this has no observable performance impact.

[WebKit Review Bot]

Comment on attachment 137289 [details]
Patch

Clearing flags on attachment: 137289

Committed r114333: <http://trac.webkit.org/changeset/114333>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.

[Ryosuke Niwa]

Thanks for the perf. analysis.

[Hajime Morrita]

Reopening due to the report: https://bugs.webkit.org/show_bug.cgi?id=84511

[Hajime Morrita]

See: https://bugs.webkit.org/show_bug.cgi?id=84497

[Ahmad Saleem]

Code seems to be changed a lot in Node.h - https://github.com/WebKit/WebKit/blob/aff87f6cbcf56b5fe448770a00f51814fa626b7c/Source/WebCore/dom/Node.h

I think this patch or patch related changes cannot be applied or already applied in other general concept. Can this be marked as "RESOLVED LATER" and "RESOLVED CONFIGURATION CHANGED"?

-> [e-mail] - any input since Comment 03 mentioned about having any past discussions with yourself? Thanks!

[Ryosuke Niwa]

We can consider doing this refactoring but keeping this 10 year old bug isn't the way to go. -> Later.