498562 - [FIX]Avoid Expand/Compress cycle for inline style sets

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[Boris Zbarsky [:bzbarsky]]

One obvious cost when setting inline style is the Expand/Compress we end up doing on the inline style in the process.  We don't _really_ need to do it in many cases, and not doing it is a 30% win on my inline style microbenchmark (in the url field) and about an 8-10% win on "real-life" testcases (the bugs this blocks).

I'm not quite sure what I think of this approach, but I do think it's pretty safe and makes a noticeable performance difference.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Attachment: Proposed fix

Comment 2

[Boris Zbarsky [:bzbarsky]]

Attachment: Now with missing ClearPropertyBit call

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 383418 [details] [diff] [review]
Now with missing ClearPropertyBit call

+ * An |nsCSSCompressedDataBlock| holds a usuallu-immutable chunk of

usually

+    // return null.  Must notbe called for shorthand properties.

not be


r=dbaron

Comment 4

[Boris Zbarsky [:bzbarsky]]

Pushed http://hg.mozilla.org/mozilla-central/rev/d8917fe0ed6a with those comment changes.